JP2006145957A - Liquid crystal optical element and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal optical element which is low-cost, and further has an ideal refractive index distribution, and functions as a high performance refractive index gradient lens. <P>SOLUTION: The variable focal length liquid crystal optical element (100) has: a first flat substrate (101); a second flat substrate (105); a liquid crystal (106) interposed between the first and the second flat substrates; an electrode pattern (200) formed on one out of the first and the second flat substrates and further having a plurality of regions (201-215) to vary effective refractive indexes for incident light in respectively different degrees; and a counter electrode (108) formed on the other out of the first and the second flat substrates to apply a voltage between the electrode pattern and it, and is characterized by having the plurality of regions concentrically disposed with distances respectively, and further the pitches of centers of the distances between the plurality of regions are uneven. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal optical element that can be used as a gradient index lens for incident light, and in particular, a liquid crystal that can be used as a gradient index lens for variable focus in a focusable optical mechanism. The present invention relates to an optical element.

  There is a growing demand for a so-called liquid crystal lens that can change the focal length in accordance with the application of voltage to the liquid crystal. This is because a mechanical mechanism for moving the lens is essential for the optical variable magnification mechanism used in conventional digital cameras and the like, and space and cost are required for that. This is because it is possible to provide a variable magnification mechanism that is small in space and low in cost.

  For example, a liquid crystal is arranged between two glass substrates, one glass substrate is punched into a lens shape, and a voltage is applied to the liquid crystal to change the effective refractive index of the liquid crystal. A liquid crystal lens in which the focal length is changed by use is known (for example, see Patent Document 1). A liquid crystal lens in which such glass is cut into a lens shape can have an ideal refractive index distribution.

  However, it takes time and labor to cut a glass substrate into a lens shape, and it has not been possible to provide a liquid crystal lens that is inexpensive and can change a high-performance focal length with little aberration.

  In addition, it is known that the focal length is minutely changed using a liquid crystal lens having a variable focal length in the automatic focusing lens device (see, for example, Patent Document 2).

  However, the specific configuration of the liquid crystal lens with variable focal length is not shown, and the liquid crystal lens with variable focal length only changes the focal length minutely. In addition, a focusing lens for changing the focal length and its moving mechanism are provided. Had.

  Further, a liquid crystal is disposed between two transparent substrates via a plurality of concentric electrode patterns and counter electrodes, and a voltage is applied to the electrode pattern to form a Fresnel zone plate made of liquid crystal. A liquid crystal panel is known in which the focal length is changed by performing spatial frequency modulation by changing the pattern of the zone plate (see, for example, Patent Document 3).

  However, in order to change the focal length, the electrode pattern itself must be changed, and a special technique for changing the electrode pattern itself depending on the situation is required. That is, the liquid crystal panel described in Patent Document 3 does not constitute a liquid crystal optical element that functions as a variable focus gradient index lens using a fixed electrode pattern.

  Further, a liquid crystal is arranged between two transparent substrates via a plurality of concentric electrodes and counter electrodes formed at equal intervals, a resistor is arranged between each electrode, and each electrode is applied by resistance division driving. A focusing mechanism using liquid crystal that changes the effective refractive index of the liquid crystal between the electrode and the counter electrode by applying a predetermined voltage to change the focal length is known (for example, see Patent Document 4). .

FIG. 13A shows an electrode 12 as described in Patent Document 4. FIG. The electrode pattern 12 has four electrodes 12-1 to 12-4 arranged concentrically at equal intervals. FIG. 13B shows equipotential potentials V1 to V4 applied to the electrodes of the electrode pattern 12 by the resistance division driving method.
FIG. 14A shows the applied voltage shown in FIG. FIG. 14B shows effective refractive indexes n1 to n4 generated according to the respective electrodes when a potential as shown in FIG. 14A is applied. As shown in FIG. 14B, if potentials V1 to V4 of an equipotential difference formed by resistance division driving are applied to the electrodes 12-1 to 12-4 of the electrode pattern 12, an equivalent step corresponding thereto. The effective refractive indexes n1 to n4 that change stepwise are generated. However, in order to obtain an ideal refractive index distribution (see 1400 in FIG. 14B) as shown in FIG. 13 of Patent Document 4, the effect that each concentric electrode 12-1 to 12-4 is generated is effective. The refractive indexes n1 to n4 must be finely adjusted independently as shown in FIG.

  As described above, in the concentric electrode patterns 12 arranged at equal pitches, it is extremely necessary to set the resistance division and finely adjust the applied voltage in order to form the gradient of the refractive index as designed. In addition, in the resistance division driving, the voltage applied to each electrode cannot be finely adjusted, so that a liquid crystal lens having an ideal refractive index distribution cannot be formed.

Japanese Patent Laid-Open No. 62-56918 (FIG. 2) JP 62-36632 A (page 3, Fig. 1) Japanese Patent No. 2651148 (first page, FIG. 1) Japanese Patent No. 3047082 (page 4, FIGS. 1, 3)

  Therefore, an object of the present invention is to provide a liquid crystal optical element that can solve the above-mentioned problems.

  Another object of the present invention is to provide a liquid crystal optical element that functions as a high-performance gradient index lens that is inexpensive and has an ideal refractive index distribution.

  A further object of the present invention is to provide a liquid crystal optical element that functions as a refractive index gradient lens capable of changing the focal point without having a movable part.

  In order to solve the above problems, a liquid crystal optical element according to the present invention includes a first planar substrate, a second planar substrate, a liquid crystal sandwiched between the first and second planar substrates, An electrode pattern formed on one of the second planar substrates and having a plurality of regions for changing the effective refractive index for incident light to different degrees, and formed on the other of the first or second planar substrate; And a counter electrode for applying a voltage between the electrode pattern, the plurality of regions are arranged concentrically at intervals, and the center pitches of the intervals between the plurality of regions are formed at unequal intervals. It is characterized by being.

  Further, the liquid crystal optical element according to the present invention is preferably applied as a refractive index gradient type lens having an image forming function and having a variable focal length.

  In the liquid crystal optical element according to the present invention, it is preferable that the plurality of regions in which the pitches of the center of the interval are formed at unequal intervals are a part of the plurality of regions.

  Furthermore, in the liquid crystal optical element according to the present invention, it is preferable that only a central portion of the opening of the liquid crystal optical element has a plurality of regions where the pitches of the center of the interval are formed at unequal intervals.

  Further, the liquid crystal optical element according to the present invention further includes a selective voltage applying means for selectively applying a voltage so as not to change the effective refractive index only to the region disposed in the peripheral part of the liquid crystal optical element. It is preferable.

  Furthermore, it is preferable that the liquid crystal optical element according to the present invention further includes a resistor connected between each of the plurality of regions and for applying a resistance-divided voltage to each of the plurality of regions.

  Furthermore, the liquid crystal optical element according to the present invention preferably further includes voltage applying means for applying different voltage values between the plurality of regions.

  Furthermore, in the liquid crystal optical element according to the present invention, it is preferable that the change amount of the effective refractive index changed by the plurality of regions is set to be substantially constant.

  Furthermore, in the liquid crystal optical element according to the present invention, it is preferable that the potential difference of each of the plurality of regions is set to be substantially constant.

  Further, in the liquid crystal optical element according to the present invention, the amount of change in the effective refractive index that is changed by the plurality of regions is set to be substantially constant, and the potential difference of each of the plurality of regions is substantially constant. It is preferable that it is set.

  Further, in the liquid crystal optical element according to the present invention, the center pitch of the interval between the plurality of regions determines the desired variable-gradient refractive index gradient lens characteristic indicating the effective refractive index value with respect to the pupil coordinates, and the maximum lens characteristic has The effective refractive index is divided by the number of the plurality of regions, the pupil coordinates of the intersection where the divided refractive index and the lens characteristic intersect are determined, and the pupil coordinates of each intersection become the central pitch of the intervals of the plurality of regions. Is preferably set.

  In order to solve the above problems, in the method for manufacturing a liquid crystal optical element according to the present invention, the liquid crystal optical element includes a first planar substrate, a second planar substrate, and a first planar substrate and a second planar substrate. A liquid crystal sandwiched between the electrodes, an electrode pattern formed on one of the first or second planar substrate and having a plurality of regions for changing the effective refractive index for incident light to different degrees, and the first or first And a counter electrode for applying a voltage to the electrode pattern, the plurality of regions being arranged concentrically at intervals, and the spacing between the plurality of regions The pitch of the center of the lens is formed at unequal intervals, and the manufacturing method determines the desired refractive index gradient type lens characteristic for variable focus indicating the effective refractive index value with respect to the pupil coordinates, and the maximum effective refractive index of the lens characteristic. Is divided by the number of areas. And determining the pupil coordinates of the intersection points where the divided effective refractive index and the lens characteristics intersect, and setting the pupil coordinates of each intersection point to be the center pitch of the interval between the plurality of regions. To do.

  According to the present invention, it is possible to provide a liquid crystal optical element that has a simple structure and can be used as a high-performance gradient index lens that can easily obtain a necessary refractive index distribution. It was.

  In addition, if the liquid crystal optical element according to the present invention is used, a variable focal length optical mechanism having no movable parts can be configured. Since the variable focal length optical mechanism using the liquid crystal optical element according to the present invention has no moving parts, it is possible to manufacture the variable focal length optical mechanism at low cost and / or space saving.

  Further, an ideal refractive index distribution that can be realized in a conventional hollow liquid crystal lens (for example, see Patent Document 1) is a conventional flat substrate type liquid crystal element arranged in parallel (for example, see Patent Document 4). However, it could not be realized, and only characteristics far from the design value could be obtained. In contrast, according to the present invention, it is possible to realize a liquid crystal optical element that functions as a gradient index lens having an ideal refractive index distribution while using a planar substrate arranged in parallel.

  A liquid crystal optical element and an optical device according to the present invention will be described below with reference to the drawings.

  FIG. 1 shows a cross-sectional view of a liquid crystal optical element 100 according to the present invention.

  A direction indicated by an arrow A in the drawing indicates a direction in which light enters the liquid crystal optical element 100. In FIG. 1, a transparent electrode 107 and an alignment film 102 having a transparent electrode pattern 200 for refractive index correction are formed on a transparent substrate 101 on the incident side. A transparent counter electrode 108 and an alignment film 104 are formed on the opposite transparent substrate 105. The liquid crystal 106 is sealed with a thickness of 20 μm between the two transparent substrates 101 and 105 and the seal member 103. Each element shown in FIG. 1 is exaggerated for convenience of explanation, and is different from an actual thickness ratio.

  The two transparent substrates 101 and 105 are made of glass, and the seal member 103 is made of resin. In the present embodiment, the liquid crystal 106 sandwiched between the two transparent substrates 101 and 105 is a homogeneous liquid crystal, but a vertically aligned liquid crystal can also be used.

  FIG. 2 shows an example of a transparent electrode pattern 200 for refractive index correction in the liquid crystal optical element 100 shown in FIG.

  As shown in FIG. 2, the electrode pattern 200 has concentric rings 201 to 215 in the range of the effective diameter 10, and each is arranged with a minute interval for insulation. Further, a predetermined AC voltage is applied between the ring body 201 and the ring body 215 from the power source 20, a resistance R 1 is provided between the ring bodies 201 and 202, and a resistance is provided between the ring bodies 202 and 203. Resistors R1 to R14 are arranged between all the ring bodies, such as R2 and a resistor R14 between the ring bodies 214 and 215. The resistors R1 to R14 all have the same resistance value.

  In FIG. 3, the relationship between each ring body 201-215 and the applied voltage is shown.

  FIG. 3A is an enlarged view of a part of the cross section of the transparent electrode pattern 200 on the transparent substrate 101. All the minute intervals between the ring bodies were set to 3 μm (for the sake of convenience, this is shown enlarged). Further, as shown in FIG. 2, the respective rings are connected to each other by resistors R <b> 1 to R <b> 14, and an AC voltage is applied from the power supply 20.

  FIG. 3B shows the effective voltage of each of the ring bodies 201 to 215 with respect to a reference voltage (voltage applied to the ring body 215, here 0 [V]). In addition, the liquid crystal used for the liquid crystal optical element generally shows an effective value response to the applied voltage. If a DC voltage component is applied to the liquid crystal for a long time, problems such as burn-in and decomposition of the liquid crystal occur. Accordingly, the liquid crystal is driven by applying an AC voltage to each transparent electrode of the liquid crystal optical element so as not to apply a DC voltage component. Further, the reference voltage 0 [V] for the liquid crystal optical element is precisely a voltage applied to the liquid crystal layer, and the voltage can be arbitrarily set. In general, the applied voltage is often set to 0 [V] as a reference, but it is also possible to set the reference voltage at another voltage value (for example, 3 [V]).

  A method for designing the transparent electrode pattern 200 will be described with reference to FIG.

  First, the lens characteristics that the liquid crystal optical element 100 is expected to have are determined. A curve 401 in FIG. 4 is an example of a lens characteristic that the liquid crystal optical element 100 is expected to have, and shows a relationship between the effective refractive index (N) and the position (X) on the pupil coordinates, It is represented by the following formula (1).

N = N ₀₁ -a ₁ X ² (1)
In this case, a ₁ can be expressed by the following formula (2).
a ₁ = 1 / (2 · f · d) (2)
Here, N is the effective refractive index at the pupil coordinate X, N ₀₁ is the reference effective refractive index, f is the focal length of the gradient index lens, and d is the thickness of the liquid crystal 106.

The thickness of the liquid crystal 106 of the liquid crystal optical element 100 is 20 μm, N ₀₁ (reference effective refractive index) is 1.74, the effective diameter (Xmax) of the liquid crystal optical element 100 is 1.22 mm, and N (Xmax ) Is 1.5, f is 155 mm from the above equations (1) and (2).
In addition, Formula (1) is a case where a spherical lens is assumed, and when an aspherical lens is assumed, the lens characteristics which the liquid crystal optical element 100 is expected to have are expressed by the following Formula (2). May be represented.

^{_{N = N 02 -a 2 X 2}} - (b 2 X 4 -c 2 X 6 + d 2 X 8 + ···) (2)
Here, N ₀₂ indicates a reference effective refractive index, and a _{2 to} d ₂ are predetermined constants.

Next, the number of rings is determined, and the maximum effective refractive index N ₀₁ possessed by the lens characteristics (curve 401) is divided equally by the number of rings (15 in this embodiment) constituting the transparent electrode pattern 200. .

Next, intersections between the effective refractive index values (N _{1 to} N ₁₅ ) divided into ₁₅ and the curve 401 are defined as P _{1 to} P ₁₅ .

Next, X _{1 to} X ₁₅ are obtained for the respective pupil coordinates corresponding to the intersection points P _{1 to} P ₁₅ .

Next, all the intervals between the ring bodies are set to 3 μm, and the ring bodies 201 to 215 are set so that the pupil coordinates X _{1 to} X ₁₅ become the gap center radius of each ring body.

  FIG. 5 shows the relationship between each ring body and the gap center radius.

  FIG. 5 shows a ring body width 501 (mm), an inner radius 502 (mm), an outer radius 503 (mm), a gap center radius 504 (mm), and a gap width 505 (mm) with respect to the ring body 204. . Since the gap width 505 between all the ring bodies is set to 0.003 mm (3 μm), the ring body width 501 (for each ring body using the gap center radius 504 (mm) obtained from FIG. mm), inner radius 502 (mm), and outer radius 503 (mm) were determined to design each ring body.

  FIG. 6 shows an example of design values of each ring body in the transparent electrode pattern 200 according to this embodiment, that is, a ring body width 501 (mm), an inner radius 502 (mm), an outer radius 503 (mm), and a gap center radius 504. (Mm) and gap width 505 (mm) are shown.

  In the present embodiment, since there is no ring body outside the outermost ring body 215, the center gap radius center of the ring body 215 is set to the effective diameter 10 (radius 1) of the optical system using the liquid crystal optical element 100. .22 mm), and the ring bodies 201 to 215 were designed, and the transparent electrode pattern 200 was created accordingly.

  FIG. 7 shows a relationship 701 between the applied voltage and the effective refractive index in the liquid crystal 106 used in this embodiment.

As shown in FIG. 7, when a homogeneous liquid crystal 106 is used and the linearly polarized light incident on the liquid crystal 106 and the alignment direction of the liquid crystal 106 are made to coincide, the non-linearity in which the effective refractive index gradually decreases as the applied voltage increases. It has characteristics. However, since there is a region that changes substantially linearly, such as between the applied voltage ranges V _{1 to} V _2, it is preferable to use this region as a region for controlling the effective refractive index.

  In the present embodiment, with respect to the transparent electrode pattern 200, V1 is applied to the ring body 201 as 1.4 [V] (reference voltage), and V2 is applied to the ring body 215 as 2.7 [V]. Configured. Further, 1.4 [V] (reference voltage) was applied to the transparent counter electrode 108.

FIG. 8 shows an example of the applied voltage applied to each ring body of the transparent electrode pattern 200 in this way. As shown in FIG. 8, each wheel is connected by resistors R _{1 to} R ₁₄ having the same resistance value, so that the voltage V2 applied to the wheel 215 is divided into 15 equal parts (resistance divided). ), Applied to each ring.

  As shown in FIG. 7, the liquid crystal 106 exhibits an effective refractive index that is inversely proportional to the applied voltage. Therefore, when the voltage shown in FIG. 8 is applied to each of the rings 201 to 215, the liquid crystal optical element 100 is It has a refractive index distribution as shown by 402 in FIG. In other words, the liquid crystal optical element 100 has a refractive index gradient type lens having a refractive index distribution 402 approximately approximate to the lens characteristic 401 determined first by applying a voltage as shown in FIG. 8 to the transparent electrode pattern 200. Function as.

  As described above, since the refractive index distribution 402 of the liquid crystal optical element 100 has a high refractive index at the center and a low refractive index around it, the liquid crystal optical element 100 functions as a convex lens. Further, when the voltage shown in FIG. 8 is applied to each of the rings 210 to 215 to have the refractive index distribution 402 shown in FIG. 4, the liquid crystal optical element 100 functions as a refractive index gradient lens having a focal length of about 155 mm.

  In addition, when the applied voltage is varied to have a refractive index distribution as indicated by 403 having a maximum effective refractive index that is approximately half that of 402 in FIG. 4, the liquid crystal optical element 100 has about the refractive index distribution 402. It functions as a refractive index gradient lens having a double magnification, that is, a focal length of about 310 mm.

Further, when the applied voltage is varied to have a substantially flat refractive index distribution as indicated by 404 in FIG. 4, the liquid crystal optical element 100 functions in the same manner as an infinite focal length, that is, a transparent glass plate. In this case, a reference voltage may be applied to all the ring bodies 201-215. In order to function as a concave lens, it is only necessary to apply a voltage to each electrode by reversing the voltage profile shown in FIG. 8, so further explanation here is omitted.
As described above, by changing the voltage applied to the rings 201 to 215, the focal length of the liquid crystal optical element 100 can be changed within a predetermined range. For example, the liquid crystal optical element 100 can be switched to function as a gradient index lens or a transparent glass plate that functions as a convex lens or a concave lens.

In the design of the transparent electrode pattern 200 described above, the maximum effective refractive index N ₀₁ of the curve 401 is equally divided by the number of rings constituting the transparent electrode pattern 200 (15 in this embodiment). Since the gap centers of the bodies are unevenly spaced, the voltage applied to each ring body of the transparent electrode pattern 200 can be set to change by the same step, and can easily be applied to each ring body by the resistance division method. A predetermined voltage can be applied. In other words, since the gap centers of the ring bodies are set at unequal intervals, the liquid crystal optical element can function as a gradient index lens having a refractive index distribution approximately approximate to the lens characteristic 401 determined first. .

  FIG. 9 shows an example of an optical apparatus 1 using the liquid crystal optical element 100 according to the present invention. The optical device 1 is an optical device such as a digital camera, and includes a liquid crystal optical element 100, a single focus lens 2, a CCD image pickup device 3, a voltage control unit 4 including an AC power source 20, and the like.

  FIG. 9A shows the case where the focus is set to infinity, and since the reference voltage is applied to the transparent electrode pattern 200 of the liquid crystal optical element 100, the liquid crystal optical element 100 does not have power, and the optical device 1 Incident light having an effective diameter 10 incident on is condensed on the CCD image pickup device 3 only by the single focus lens 2.

  FIG. 9B shows a case where the focus is adjusted to a short distance. By applying a voltage such as 801 shown in FIG. 8 to the transparent electrode pattern 200 of the liquid crystal optical element 100, the liquid crystal optical element 100 is 4 functions as a convex lens having a refractive index distribution 402 as indicated by 402 in FIG. Therefore, the incident light that has entered the optical device 1 has a focal point different from the focal length (see 7 in the figure) of the single-focus lens 2 by the liquid crystal optical element 100 and the single-focus lens 2 as indicated by 6 in the figure. Focused on the CCD image sensor 3 at a distance.

  Further, if the voltage value applied to the transparent electrode pattern 200 of the liquid crystal optical element 100 is varied in accordance with a signal from a predetermined autofocus adjustment circuit, an autofocus optical system can be easily configured without using moving parts. Is possible. If an optical system or an autofocus optical system capable of switching the focal length without using such moving parts is used for a digital camera or a mobile phone, there is a great advantage that space saving and cost reduction can be achieved.

  FIG. 10 shows an example of another voltage application method applicable to the liquid crystal optical element 100 according to the present invention.

2 and 3, resistors having substantially the same resistance value are arranged between the respective ring bodies 201 to 215, and a voltage is applied by a resistance division method. On the other hand, in FIG. 10, the drive IC circuit 21 is arranged so that the set voltage values can be applied to the respective rings 201 to 215. Therefore, if the driving IC circuit 21 shown in FIG. 10 is used, it is not necessary to connect the respective wheels 201 to 215 with the resistors R _{1 to} R ₁₄ . The driving IC circuit 21 may have any configuration as long as a preset voltage, for example, V1 to V15 shown in FIG. 8 can be applied to each of the wheels 201 to 215. It can be easily configured by circuit technology. Further, when the drive IC circuit 21 is used, all the set values of the voltages applied to the respective wheels 201 to 215 may be controlled by signals from the outside, and the drive IC circuit 21 is provided with a storage unit. Alternatively, it may be stored in the storage unit in advance.

  FIG. 11 shows a setting example of another transparent electrode pattern applicable to the liquid crystal optical element 100 according to the present invention.

  FIG. 11 shows another refractive index profile 1100 that the liquid crystal optical element 100 has. The difference between the distribution 1100 and the refractive index distribution 402 shown in FIG. 4 is that (1) the distribution 1100 further subdivides the central portion A of the distribution 402, and (2) the distribution 1100 shows the peripheral portions B and C of the distribution 402. This is an omitted point.

In the central part A, an intersection point P ₀ between the intermediate point P 1 and the Y axis and the effective refractive index N ₀₁ is provided, and the central ring body 201 is divided into 201-1 and 201-2 accordingly. did. This is because the ring body 201 of the central portion A is formed larger than the others, and the central portion of the refractive index distribution 402 of the liquid crystal optical element 100 is not gently formed. This is intended to approach the ideal lens characteristic 401.

Further, in the peripheral portions B and C, one ring body 220 is formed so that the intersection points P _{11 to} P ₁₅ in the lens characteristics 401 all have an effective refractive index N ₁₅ . It should be noted that all the intersection points P _{11 to} P ₁₆ may be replaced by N ₁₃ instead of N ₁₅ so as to form one ring body 220. This is because the peripheral portion of the refractive index distribution does not significantly affect the lens characteristics, and the width of the ring corresponding to the peripheral portion becomes very small and is difficult to form. As shown in the peripheral portions B and C of FIG. 11, the lens characteristics of the liquid crystal optical element 100, particularly the function of changing the focal length, is great even if the ring bodies 211 to 215 are not formed and replaced with one ring body 220. There is no effect.

  Further, although not shown, a ring body having the same width may be formed in the peripheral portion of the refractive index distribution instead of the ring body corresponding to the peripheral portion as shown in FIG. For example, instead of the ring bodies 211 to 215 shown in FIG. 4, five ring bodies having an average width of the ring bodies 211 to 215 may be provided. As described above, even if formed in this manner, the lens characteristics of the liquid crystal optical element 100, particularly the function of changing the focal length, are not greatly affected.

  As described above, it is not always necessary to form all the annular bodies 201 to 215 in the transparent electrode pattern 200 of the liquid crystal optical element 100 at unequal intervals at the centers of the intervals, which greatly affects the lens characteristics. There may be a case where it does not have to be formed at unequal intervals in a portion where there is no.

  FIG. 12 shows an example of another refractive index distribution 1200 that the liquid crystal optical element 100 has.

The example of FIG. 12 shows an example in which the liquid crystal optical element 100 has different refractive index distributions using the same annular bodies 201 to 215 as the annular bodies shown in FIG. Here, the maximum effective refractive index N ₀₁ is equally divided into ten, and the distribution 1200 is configured using only the rings 201 to 210. Thus, the distribution 1200 different from the refractive index distribution 402 shown in FIG. Since the lens characteristic 1201 approximated by the distribution 1200 draws a steeper curve than the curve of the lens characteristic 401 shown in FIG. 4, when the liquid crystal optical element 100 has the distribution 1200, the liquid crystal optical element 100 is more focused. The distance can be shortened.
In this way, it is possible to change the focal length of the liquid crystal optical element 100 by changing the refractive index distribution of the liquid crystal optical element 100 without changing the pattern of the ring.

It is a figure which shows an example of sectional drawing of the liquid crystal optical element concerning this invention. It is a figure which shows an example of a transparent electrode pattern. (A) is a partially enlarged view of a transparent electrode pattern, and (b) is a diagram showing an example of a voltage applied to each ring body. It is a figure for demonstrating the design method of a transparent electrode pattern. It is a figure for demonstrating the design method of each ring body. It is a figure which shows an example of the design value of a transparent electrode pattern. It is a figure which shows the relationship between the applied voltage of a liquid crystal, and an effective refractive index. It is a figure which shows the example of a voltage applied to a transparent electrode pattern. It is a figure which shows an example of the optical mechanism using the liquid crystal optical element which concerns on this invention. It is a figure for demonstrating the other voltage application method to a transparent electrode pattern. It is a figure which shows the example of a change of a ring body pattern. It is a figure which shows the further another voltage example applied to a transparent electrode pattern. It is a figure which shows a prior art example. It is a figure which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Liquid crystal optical element 101, 105 Transparent substrate 106 Liquid crystal 107 Transparent electrode 108 Transparent counter electrode 200 Transparent electrode pattern 201-215 Ring

Claims (11)

In a liquid crystal optical element that functions as a gradient index lens for variable focus with respect to incident light,
A first planar substrate;
A second planar substrate;
Liquid crystal sandwiched between the first and second planar substrates;
An electrode pattern formed on one of the first or second planar substrate and having a plurality of regions for changing the effective refractive index with respect to the incident light to different degrees;
A counter electrode formed on the other of the first or second planar substrate and for applying a voltage to the electrode pattern;
The plurality of regions are arranged concentrically at intervals, and the center pitches of the intervals between the regions are formed at unequal intervals.
A liquid crystal optical element characterized by the above.   2. The liquid crystal optical element according to claim 1, wherein the plurality of regions in which the pitches of the centers of the intervals are formed at unequal intervals are a part of the plurality of regions.   3. The liquid crystal optical element according to claim 2, wherein the liquid crystal optical element has a plurality of regions in which pitches of the center of the interval are formed at unequal intervals only at a central portion of the opening of the liquid crystal optical element.   2. The liquid crystal optical element according to claim 1, further comprising selective voltage applying means for selectively applying a voltage so as not to change an effective refractive index only to a region disposed in a peripheral portion of the liquid crystal optical element.   2. The liquid crystal optical element according to claim 1, further comprising a resistor connected between each of the plurality of regions and applying a resistance-divided voltage to each of the plurality of regions.   The liquid crystal optical element according to claim 1, further comprising voltage applying means for applying different voltage values between the plurality of regions.   The liquid crystal optical element according to claim 1, wherein a change amount of an effective refractive index that is changed by the plurality of regions is set to be substantially constant.   The liquid crystal optical element according to claim 1, wherein each of the plurality of regions is set to have a substantially constant potential difference.   The amount of change in effective refractive index that is changed by the plurality of regions is set to be substantially constant, and the potential difference of each of the plurality of regions is set to be substantially constant. The liquid crystal optical element according to any one of the above. The central pitch of the interval between the plurality of regions is
Determine the desired variable gradient refractive index gradient lens characteristic showing the effective refractive index value for the pupil coordinates,
Dividing the maximum effective refractive index of the lens characteristics by the number of the plurality of regions,
Determine the pupil coordinates of the intersection where the divided effective refractive index and the lens characteristic intersect,
10. The liquid crystal optical element according to claim 1, wherein the pupil coordinates of each intersection point are set to be a center pitch of an interval between the plurality of regions. A method of manufacturing a liquid crystal optical element that acts as a variable-focus gradient index lens for incident light, the liquid crystal optical element comprising: a first planar substrate; a second planar substrate; and the first and first planar substrates. A liquid crystal sandwiched between two planar substrates, and an electrode formed on one of the first or second planar substrates and having a plurality of regions for changing the effective refractive index with respect to the incident light to different degrees. A pattern and a counter electrode formed on the other of the first or second planar substrate and for applying a voltage between the electrode pattern, and the plurality of regions are concentrically spaced from each other. And the pitches of the centers of the intervals between the plurality of regions are formed at unequal intervals, and the manufacturing method includes:
Determine the desired variable focus gradient index lens characteristic showing the refractive index value relative to the pupil coordinates,
Dividing the maximum effective refractive index of the lens characteristics by the number of the plurality of regions,
Determine the pupil coordinates of the intersection where the divided refractive index and the lens characteristic intersect,
The pupil coordinates of each intersection point are set to be the center pitch of the interval between the plurality of regions.
The manufacturing method characterized by having a process.

Images