WO2010052869A1 - Liquid crystal lens and imaging device - Google Patents

Liquid crystal lens and imaging device Download PDF

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Publication number
WO2010052869A1
WO2010052869A1 PCT/JP2009/005756 JP2009005756W WO2010052869A1 WO 2010052869 A1 WO2010052869 A1 WO 2010052869A1 JP 2009005756 W JP2009005756 W JP 2009005756W WO 2010052869 A1 WO2010052869 A1 WO 2010052869A1
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
electrode
lens
electrodes
voltage
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PCT/JP2009/005756
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French (fr)
Japanese (ja)
Inventor
有田真一
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シャープ株式会社
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Publication of WO2010052869A1 publication Critical patent/WO2010052869A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0087—Simple or compound lenses with index gradient
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/12—Fluid-filled or evacuated lenses
    • G02B3/14—Fluid-filled or evacuated lenses of variable focal length
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1343—Electrodes
    • G02F1/134309—Electrodes characterised by their geometrical arrangement
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
    • G02F1/13471—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells

Definitions

  • digital cameras high-quality digital still cameras and digital video cameras
  • digital cameras are rapidly spreading.
  • small and high-quality digital cameras have been mounted on mobile devices such as mobile phone terminals, and the development of smaller and thinner digital cameras is also underway.
  • an optical system for forming an image on an image sensor is usually composed of several lenses in order to eliminate aberrations.
  • a drive mechanism actuator
  • changes the focal length of the combination lens and the distance between the lens and the image sensor is necessary.
  • the mechanism is complicated, and because a movable part is required, impact resistance is required. The problem is that it is low.
  • a method using a liquid crystal lens that can obtain a lens effect by changing a refractive index distribution in the liquid crystal by applying a voltage is known.
  • a liquid crystal lens in which a control electrode and a transparent flat electrode arranged in an axial symmetry are arranged to face each other and a liquid crystal layer is interposed between the two electrodes.
  • a voltage when a voltage is applied, an axially symmetric electric field distribution about the center of the control electrode is formed, and an axially symmetric refractive index distribution is generated in the liquid crystal layer, thereby obtaining a lens effect.
  • the electric field distribution can be varied to arbitrarily control the focal length.
  • the refractive index distribution that is symmetric with respect to the central axis of the hole of the electrode can be made asymmetric.
  • a deflection effect on the incident light is generated, and the focal position can be changed not only in the control of the focal length in the optical axis direction but also in a plane perpendicular to the optical axis.
  • the liquid crystal lens can change the focal length and the optical axis direction by controlling the voltage applied to its electrode and changing the refractive index distribution in the liquid crystal lens surface, it is expected to be applied to the imaging optical system. ing.
  • a conventional liquid crystal lens as an optical lens for an imaging device, it is necessary to capture light in a direction that matches the target angle of view, but each liquid crystal layer of the liquid crystal lens is aligned in one direction, There is a difference in light collection characteristics depending on the incident direction and angle of the incident light beam. This has a great influence on a light ray incident in a plane parallel to the alignment direction.
  • the electric field distribution in the divided portion of the electrode is distorted, which is a factor that affects the imaging characteristics of the lens.
  • FIG. 8 schematically shows a cross-sectional view of a conventional liquid crystal lens in which a liquid crystal layer 601 is provided between a pair of electrodes 603a and 603b facing each other, and a circular pattern hole is provided in the electrode 603a.
  • the liquid crystal molecules 602 are expressed as a substantially spheroid from the viewpoint of dielectric constant, the major axis of the liquid crystal (nematic liquid crystal) molecules 602 is oriented in the direction of the electric field 604 by applying a voltage between the electrodes as shown in FIG. And the refractive index distribution in the liquid crystal layer changes based on the dielectric constant of the liquid crystal molecules.
  • the incident light 603 to the liquid crystal lens is condensed at one point like the transmitted light 604.
  • the applied electric field is weak in the vicinity of the part where the electrode is divided, so the tilt of the liquid crystal molecules is slightly reduced, and the condensing point is shifted. Affects imaging characteristics.
  • FIG. 9 schematically shows the liquid crystal molecules 602 as viewed from the cross-sectional direction of the liquid crystal lens (divided by the plane of the alignment direction). Since the refractive index varies depending on the minor axis direction of the spheroid and the major axis direction of (2), different characteristics are exhibited depending on the incident angle and direction of the light beam. The influence on the image formation due to the difference in the incident direction and angle of the light beam appears more conspicuously in a portion where electrolysis is weak, such as in the vicinity where the electrode is divided.
  • FIG. 10 schematically shows the liquid crystal molecules viewed from the electric field direction (optical axis direction). However, when two light beams incident on the same plane and with the same incident angle are considered, the alignment direction of the liquid crystal.
  • the vicinity of the divided portion of the electrode affects the imaging characteristics, and the influence is asymmetric with respect to the optical axis of the lens. . Since the imaging lens needs to capture a light beam having a certain angle of view, as the incident angle to the liquid crystal lens increases, the asymmetry increases and correction becomes difficult. In particular, when the electrode dividing direction coincides with the alignment direction of the liquid crystal layer (liquid crystal molecules), the imaging characteristics in the vicinity thereof are greatly degraded and the asymmetry is also increased. That is, when used as an imaging lens, there is a problem that the lens has a large imaging characteristic.
  • the present invention has been made in view of such circumstances, and it is intended to provide a liquid crystal lens capable of preventing deterioration in imaging performance, improving asymmetry and obtaining good image quality, and an imaging apparatus using the liquid crystal lens. Objective.
  • the present invention is a liquid crystal lens having a liquid crystal layer between a control electrode and a fixed electrode facing each other, and controlling the alignment of liquid crystal molecules of the liquid crystal layer by applying a voltage between the facing electrodes.
  • the control electrode is divided into at least two regions, and the alignment direction of the liquid crystal layer does not coincide with the direction of the boundary between the opposing control electrodes in the lens effective region.
  • control electrode is a punched electrode having a hole, and is divided in the radial direction of the hole by the boundary, and a voltage is applied to each electrode independently.
  • the present invention is characterized in that the alignment direction of the liquid crystal layer and the direction of the boundary between the opposing control electrodes form a maximum angle.
  • the present invention has a liquid crystal layer between a control electrode and fixed electrodes provided on both sides of the control electrode so as to face each other, and a voltage is applied between the facing electrodes to thereby form liquid crystal molecules in the liquid crystal layer.
  • the control electrode is divided into at least two regions, and the orientation direction of the liquid crystal layer does not coincide with the direction of the boundary between the opposing control electrodes in the lens effective region. It is characterized by.
  • control electrode is a punched electrode having a hole, and is divided in the radial direction of the hole by the boundary, and a voltage is applied to each electrode independently.
  • the present invention is characterized in that the alignment direction of the liquid crystal layer and the direction of the boundary between the opposing control electrodes form a maximum angle.
  • the present invention is characterized in that the alignment directions of the two liquid crystal layers are vertical.
  • the present invention controls the direction of the optical axis of light incident on the image pickup device by controlling the voltage applied to the liquid crystal lens according to any one of claims 1 to 7, the image pickup device, and the liquid crystal lens. And an optical axis control unit.
  • the liquid crystal lens having the divided control electrodes it is possible to reduce the influence of the deterioration of the light converging characteristics of the light rays at the electrode dividing positions and to improve the imaging characteristics.
  • the optical axis can be adjusted, and an effect that it is possible to capture a high-quality image can be obtained.
  • First Embodiment> 1 and 2 are a front view and a cross-sectional view taken along line AA ′ showing the configuration of the liquid crystal lens 100 according to the first embodiment.
  • the liquid crystal lens 100 includes a transparent first electrode 103, a second electrode 104, a transparent third electrode 105, a liquid crystal layer 106 disposed between the second electrode 104 and the third electrode 105, The first insulating layer 107 disposed between the first electrode 103 and the second electrode 104; the second insulating layer 108 disposed between the second electrode 104 and the third electrode 105; The third insulating layer 109 is disposed outside the third electrode 103, and the fourth insulating layer 110 is disposed outside the third electrode 105.
  • the electrode 103 and the electrode 105 are each made of a transparent material having light transmittance.
  • the above-mentioned electrode and insulator are each comprised with the material which has transparent light transmittance.
  • the second electrode 104 has a circular hole 104e and is composed of four electrodes 104a, 104b, 104c, and 104d that are divided vertically and horizontally as shown in the front view of FIG. Is referred to as a punched electrode).
  • a voltage can be applied independently to each of the electrodes 104a, 104b, 104c, and 104d. Then, by applying a voltage between the electrodes 103, 104, and 105 sandwiching the liquid crystal layer 106 to control the alignment of the liquid crystal molecules, the inside of the circular hole 104e formed by the second electrode 104 (this corresponds to the lens effective region).
  • the refractive index distribution of the liquid crystal layer 106 changes to function as an optical lens.
  • the vertical division direction is indicated by a line segment 140a
  • the horizontal division direction is indicated by a line segment 140b.
  • liquid crystal molecules are aligned in one direction
  • the alignment direction is indicated by a line segment 130.
  • the direction of the line segment 130 is the direction of the boundary between two electrodes (electrodes 104a and 104b, electrodes 104b and 104d, electrodes 104a and 104c, electrodes 104c and 104d) facing each other. They are arranged in a direction that does not match (the direction of the line segments 140a and 140b).
  • the alignment direction of the liquid crystal molecules does not coincide with the boundary direction between the two electrodes, and the direction between the alignment direction of the liquid crystal molecules and the boundary direction between the electrodes is maximized. desirable.
  • it is desirable that the angle formed by the two boundary directions (two line segments 140a and 140b) intersect is divided into two. In the example shown in FIG. 1, since the angle formed by the line segments 140a and 140b is 90 °, the angle formed by each of the two line segments 140a and 140b and the line segment 130 is 45 °.
  • This example is a case of a four-divided electrode, but in the case of a two-divided electrode, the angle formed by the dividing direction and the orientation direction is 90 °. Further, in the case of an 8-divided electrode, the angle formed by the dividing direction and the alignment direction is 22.5 °.
  • the dimensions of the liquid crystal lens 100 are shown below.
  • the size of the circular hole 104e of the second electrode 104 is about ⁇ 2 mm, the distance from the first electrode 103 is 70 ⁇ m, and the thickness of the second insulating layer 108 is 700 ⁇ m.
  • the thickness of the liquid crystal layer 106 is 60 ⁇ m.
  • the alignment direction 130 of the liquid crystal layer 106 is a direction that forms 45 degrees with the dividing directions 140a and 140b of the divided electrode 104, respectively, and the angle formed by the dividing directions 140a and 140b of the electrode and the alignment direction of the liquid crystal is maximized. It is arranged.
  • the insulating layer 108 is made of, for example, a transparent glass having a thickness of 700 ⁇ m in order to increase the diameter.
  • the distance at the boundary between the two opposing electrodes should be the shortest distance that can maintain a state in which no discharge occurs. desirable.
  • the first electrode 103 and the second electrode 104 are different layers, but they may be formed on the same surface.
  • the shape of the first electrode 103 is a circle having a smaller size than the circular hole 104e of the second electrode 104, and is arranged at the position of the hole 104e of the second electrode 104. It is set as the structure which provided the electrode extraction part in the slit of this.
  • the electrodes 104a, 104b, 104c, and 104d constituting the first electrode 103 and the second electrode can be independently voltage controlled. With this configuration, the overall thickness can be reduced.
  • a voltage is applied between the transparent third electrode 105 and the second electrode 104 made of an aluminum thin film or the like, and at the same time, the first electrode 103 and the second electrode
  • a voltage between the electrodes 104 it is possible to form an axial electric field gradient on the central axis 120 of the second electrode 104 having the circular hole 104e. Due to the electric field gradient around the edge of the circular electrode formed in this way, the liquid crystal (e.g., nematic liquid crystal) molecule in the shape of an elongated spheroid of the liquid crystal layer 106 has its long axis directed in the direction of the electric field.
  • the liquid crystal e.g., nematic liquid crystal
  • the refractive index distribution of the extraordinary light changes from the center to the periphery of the circular electrode due to the change in the orientation distribution of the liquid crystal layer 106, so that it can function as a lens.
  • the refractive index distribution of the liquid crystal layer 106 can be freely changed by applying a voltage to the first electrode 103 and the second electrode 104, and optical characteristics such as a convex lens and a concave lens can be freely controlled. Is possible.
  • an effective voltage of 20 Vrms is applied between the first electrode 103 and the third electrode 105, and an effective voltage of 70 Vrms is applied between the second electrode 104 and the third electrode 105.
  • the voltage applied to the first electrode 103 may be made smaller than the voltage applied to the second electrode 104 in this way.
  • the voltage applied to the first electrode 103 may be controlled.
  • the liquid crystal driving voltage (voltage applied between the electrodes) is a sine wave or a rectangular wave AC waveform with a duty ratio of 50%.
  • the voltage value to be applied is represented by an effective voltage (rms: root mean square).
  • an AC sine wave of 100 Vrms has a voltage waveform having a peak value of ⁇ 144V.
  • 1 kHz is used as the frequency of the AC voltage.
  • an effective voltage of 90 Vrms is applied between the first electrode 103 and the third electrode 105, and the second electrode 104 is used.
  • an effective voltage of 30 Vrms may be applied between the first electrode and the third electrode 105 so that the applied voltage to the first electrode is higher than the applied voltage to the second electrode.
  • the refractive index was axially symmetric when the same voltage was applied.
  • the distribution is an asymmetric distribution with the axis shifted with respect to the second electrode central axis 120 having the circular hole 104e, and the effect that the incident light is deflected from the straight traveling direction is obtained.
  • the direction of incident light deflection can be changed by appropriately changing the voltage applied between the divided second electrode 104 and the third electrode 105.
  • the position is shifted to the position indicated by reference numeral 121.
  • the shift amount is 40 ⁇ m, for example.
  • the alignment direction of the liquid crystal molecules in the liquid crystal layer 106 is a direction that does not coincide with the direction of the boundary between the two electrodes
  • the alignment direction of the liquid crystal molecules is the same as the alignment direction between the liquid crystal molecules and the electrodes. It is not limited to the direction in which the angle formed with the boundary direction is maximized. As shown in FIG. 3, eight line segments connecting the center point P1 of the circular hole 104e of the second electrode 104 and each of the eight end points P2 to P9 of the four electrodes 104a, 104b, 104c, and 104d.
  • the direction excluding the directions 141 to 148 may be the alignment direction of the liquid crystal molecules of the liquid crystal layer 106.
  • the light rays at the electrode division points are excluded except for the direction of the line segment 141 to the line segment 148, the direction of the line segment 142 to the line segment 143, the direction of the line segment 144 to the line segment 145, and the direction of the line segment 146 to the line segment 147. It is possible to reduce the influence of the deterioration of the light condensing characteristics and improve the imaging characteristics.
  • the liquid crystal lens 100 has a structure in which the division direction of the second electrode (control electrode) 104 and the alignment direction of the liquid crystal layer 106 are not aligned with each other, and therefore, the incident angle into the circular hole 104e of the liquid crystal lens 100. Therefore, the light condensing characteristic with respect to the light having the light is improved, and the blur of the image can be reduced.
  • the liquid crystal layer is composed of a single layer, but the present invention is not limited to this.
  • the liquid crystal layer By configuring the liquid crystal layer with a plurality of layers, it is possible to obtain a strong lens power. Furthermore, since the same lens power can be constituted by a combination of thin liquid crystal layers, the operation speed can be improved. In addition, a lens effect can be obtained regardless of the polarization direction of incident light by combining the polarization directions.
  • ⁇ Second Embodiment> 4 and 5 are a front view and a BB ′ sectional view showing the configuration of the liquid crystal lens 200 according to the second embodiment.
  • the liquid crystal lens 200 in the present embodiment includes a transparent first electrode 203, an opaque second electrode 204, transparent third electrodes 205a and 205b, a second electrode 204, and a third electrode 205a (205b).
  • the second electrode 204 has a circular hole, and is composed of four electrodes 204a, 204b, 204c, and 204d divided vertically and horizontally as shown in the front view of FIG.
  • the voltage can be applied independently to each electrode.
  • the divided direction of the electrode 204 is indicated by electrode dividing direction line segments 240a and 240b, respectively.
  • the first electrode 203 is arranged at the center position of the hole of the second electrode 204, and electrode lead lines 203a and 203b are provided in a slit portion between the electrodes 204b and 204d.
  • a voltage is applied to the electrode 203.
  • Each of the first electrode 203 and the electrodes 204a, 204b, 204c, and 204d constituting the second electrode can be independently voltage controlled.
  • the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 are each composed of two liquid crystal layers, and the liquid crystal layers 206a1 and 206b1 and the liquid crystal layers 206a2 and 206b2 are arranged to have the same polarization direction. Further, the liquid crystal layers 206a1 (206b1) and 206a2 (206b2) are arranged so as to be aligned in different directions.
  • the condensing characteristics are affected by the angle and direction of light rays incident on the liquid crystal layers 206a1, 206a2, 206b1, and 206b2, and there is a large difference in characteristics in a plane parallel to the alignment direction. The condensing characteristics can be improved by disposing the liquid crystal layers in different directions from each other.
  • the liquid crystal layers 206a1 (206b1) and 206a2 (206b2) are arranged so that the polarization direction is 90 degrees.
  • Each of the liquid crystal layer 206a1 (206b1) and the liquid crystal layer 206a2 (206b2) can satisfy the lens effect only for light in one polarization direction, and thus the polarization of the liquid crystal layer 206a1 (206b1) and the liquid crystal layer 206a2 (206b2).
  • each liquid crystal is controlled by applying a voltage between the electrodes 203, 204, and 205 sandwiching the liquid crystal layers 206a1 and 206a2 (206b1 and 206b2), and the liquid crystal molecules in the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2. Alignment control is performed.
  • the liquid crystal layers 206a1 and 206b1 are arranged so that the alignment direction is one direction of the line segment 230 (direction of the arrow), and the liquid crystal layers 206a2 and 206b2 are one direction of the alignment direction of the line segment 231 ( (Direction of arrow). Both the line segments 230 and 231 are arranged so as not to coincide with the electrode dividing direction line segments 240a and 240b.
  • the liquid crystal layers 206a1 and 206b1 and the liquid crystal layers 206a2 and 206b2 are arranged to have the same light distribution direction, but the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 may be arranged to have the same light distribution direction. Good. However, in this case, since the shift of the focal position in the two polarization directions becomes large, it is necessary to control so that the potential difference between the electrode 204 and the electrode 205a is smaller than the potential difference between the electrode 204 and the electrode 205b.
  • the dimensions of the liquid crystal lens 200 are shown below.
  • the size of the circular hole of the second electrode 204 is about ⁇ 3 mm, and the thickness of the insulating layer 208a (208b) is 700 ⁇ m.
  • the thickness of the liquid crystal layer 206 is 30 ⁇ m.
  • the alignment direction line segments 230 and 231 of the liquid crystal layers 206a and 206b are directions that form 45 degrees with the electrode division direction line segments 240a and 240b, respectively.
  • the electrode division direction, the liquid crystal layers 206a1 and 206a2, and the liquid crystal layer The arrangement is such that the angle formed by the orientation directions of 206b1 and 206b2 is maximized.
  • the insulating layer 208a (208b) is made of, for example, a transparent glass having a thickness of 700 ⁇ m for the purpose of increasing the diameter. With such an arrangement, it is possible to disperse the influence on the light condensing characteristics due to the distortion of the electric field at the electrode division location and the influence on the light condensing characteristics in the alignment direction of the liquid crystal. It is possible to improve.
  • a second electrode composed of a transparent third electrode 205a (205b) and an aluminum thin film is used.
  • the liquid crystal molecules of the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 are aligned in the direction of the electric field gradient and can function as a lens.
  • the refractive index distribution of the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 can be freely changed by applying a voltage to the first electrode 203 and the second electrode 204. Characteristic control can be performed.
  • the refractive index distribution that is axially symmetric when the same voltage is applied becomes a circular hole.
  • the second electrode central axis 220 has an asymmetrical distribution with the axis shifted, and the effect that the incident light is deflected from the straight traveling direction can be obtained, and the focal position can be controlled in a plane perpendicular to the optical axis. It is.
  • the liquid crystal lens 200 has a structure in which the dividing direction of the control electrode 204 and the alignment directions of all the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 constituting the lens do not coincide with each other. Therefore, the light condensing characteristic with respect to the light having the angle to be improved is improved, and the blur of the image can be reduced.
  • FIG. 6 is a functional block diagram showing an overall configuration of an imaging apparatus according to the third embodiment of the present invention.
  • reference numeral 200 denotes a liquid crystal lens.
  • the same parts as those of the liquid crystal lens 200 in the second embodiment are denoted by the same reference numerals, and a part of the description including application examples thereof will be omitted. Note that the reduction in image formation characteristics due to the electrode dividing direction and the liquid crystal layer arranging direction is the same as that described in the second embodiment.
  • the imaging apparatus 300 in FIG. 6 includes an imaging unit 310, a control unit 303 that controls the voltage applied to the liquid crystal lens, and a video processing unit 305 that converts a signal from the imaging device into a video signal.
  • An image pickup element 302 that forms an image on the image pickup element 304 and the image pickup element 304 is provided.
  • the imaging lens 302 is configured by a combination of the liquid crystal lens 200 including the four divided control electrodes and the four liquid crystal layers described in the second embodiment, and the optical lens 301 made of glass. In the present embodiment, the liquid crystal lens 200 is used.
  • the present invention is not limited to this, and any liquid crystal lens may be used as long as it has divided electrodes and is arranged so that the dividing direction of the electrodes does not coincide with the alignment direction of the liquid crystal layer.
  • the optical lens 301 may be made of plastic or the like, and the combination as an imaging lens is not particularly limited to this embodiment.
  • a configuration in which a liquid crystal lens is inserted between glass lenses and the incident angle of incident light on the liquid crystal lens is suppressed by the glass lens may be employed. In this case, since the incident angle to the liquid crystal lens is reduced, an imaging lens with better optical characteristics can be realized.
  • the control unit 303 includes voltage control units 303a, 303b, 303c, and 303d that control the voltage applied to the liquid crystal lens 200.
  • Each of the voltage control units 303a, 303b, 303c, and 303d of the control unit 303 controls the applied voltage of each of the control electrodes 204a, 204b, 204c, and 204d provided in the liquid crystal lens 200.
  • the imaging lens 302 forms an image of light from a subject to be imaged on the corresponding imaging element 304.
  • An image formed by the imaging lens 302 is photoelectrically converted by the imaging element 304, and an optical signal is converted into an electrical signal.
  • the electric signal converted by the image sensor 304 is converted by the video processing unit 305 using a preset parameter or the like.
  • the control unit 303 applies a voltage to the control electrodes 204a, 204b, 204c, and 204d of the liquid crystal lens 200 so as to obtain an optimum focal position.
  • a voltage is applied to the control electrodes 204a, 204b, 204c, and 204d so as to change the direction of the optical axis if the imaging position is deviated.
  • the applied voltage may be controlled so that the voltage in the direction in which the optical axis is desired to be shifted is high.
  • the voltage applied to the control electrode 203 is controlled so as to change the focal position. In this control, the applied voltage value is increased when the focal position is far away, and conversely, the applied voltage is decreased as the focal position is brought closer.
  • the liquid crystal lens 200 can control the focal position freely not only in the optical axis direction but also in a plane perpendicular to the optical axis only by controlling the voltage, and there is no need for a driving mechanism for focusing. . Therefore, the imaging apparatus 300 can be reduced in size with a simple structure. In addition, since the arrangement is such that the dividing direction of the control electrode and the alignment direction of all the liquid crystal layers do not coincide with each other, it is possible to realize an imaging device capable of suppressing deterioration in imaging performance and obtaining good image quality.
  • FIG. 7 is a functional block diagram showing the overall configuration of the imaging apparatus 400 according to the embodiment of the present invention.
  • the present embodiment is a multi-lens imaging device configured by combining a plurality of imaging devices 300 described in the third embodiment (four in this example).
  • the same parts as those of the image pickup apparatus 300 in the third embodiment are denoted by the same reference numerals, and a part of the description including the application examples thereof will be omitted and briefly described. Note that the reduction in image formation characteristics due to the electrode dividing direction and the liquid crystal layer arranging direction is the same as that described in the second embodiment.
  • the imaging apparatus 400 shown in FIG. 7 is an example of an imaging apparatus that includes four systems of imaging units 310a, 310b, 310c, and 310d.
  • the imaging unit 310a includes an imaging lens 302 and an imaging element 304, and the configurations of the imaging units 310b, 310c, and 310d are the same.
  • the four imaging units 310a, 310b, 310c, and 310d capture an imaging target and output four systems of image signals.
  • the flow of an image signal will be described by taking one imaging unit 310a as an example.
  • An image formed by the imaging lens 302 is photoelectrically converted by the imaging element 304, and an optical signal is converted into an electrical signal.
  • the electrical signal converted by the image sensor 304 is converted by the video processing unit 3051 according to preset parameters or the like.
  • the video signal converted by the video processing unit 3051 enters the video composition unit 401.
  • image signals from the other imaging units 310 b, 310 c, and 310 d are converted by the corresponding video processing units 3052, 3053, and 3054 and input to the video composition processing unit 401.
  • the video composition processing unit 401 synthesizes the four video signals captured by the four image capturing units 310a, 310b, 310c, and 310d into one video signal while synchronizing them, and outputs it as a high-definition video.
  • the video composition processing unit 401 generates a control signal based on the determination result when the combined high-resolution video is deteriorated from a predetermined determination value.
  • each of the control units 3031 to 3034 Based on the control signal, each of the control units 3031 to 3034 performs optical axis control of the corresponding imaging lens 302, and the video composition processing unit 401 determines again. If the determination result is good, a high-definition video is output, and if it is bad, the imaging lens 302 is controlled again to output a high-definition video.
  • the four-eye configuration includes four imaging units 300a to 300d.
  • the number is not limited, and five or six eyes or more may be used.
  • the green image pickup unit achieves high definition
  • a high-definition color image may be obtained by synthesizing the video signal from the blue imaging unit.
  • An imaging device with high sensitivity can be realized by such a method, and a bright and good image quality can be obtained.
  • the liquid crystal lens 200 can freely control the focal position not only in the optical axis direction but also in a plane perpendicular to the optical axis only by controlling the voltage. There is no need for a drive mechanism, and the size can be reduced with a simple structure.
  • the liquid crystal lens has a structure in which the dividing direction of the control electrode and the alignment direction of all the liquid crystal layers do not coincide with each other, an image pickup apparatus capable of suppressing deterioration in imaging performance and obtaining good image quality is provided. realizable.
  • the orientation direction of the liquid crystal layer is determined so as not to coincide with the direction of the boundary between the opposing control electrodes. It is possible to reduce the influence of the deterioration of the light condensing characteristic of the light beam in the vicinity of the boundary portion of the control electrode and improve the imaging characteristic. Further, by incorporating this liquid crystal lens into the image pickup apparatus, it becomes possible to adjust the optical axis with high accuracy and to pick up a high-quality image.
  • DESCRIPTION OF SYMBOLS 100 ... Liquid crystal lens, 103 ... 1st electrode, 104 ... 2nd electrode, 105 ... 3rd electrode, 106 ... Liquid crystal layer 106, 107 ... 1st insulation Layer, 108 ... second insulating layer, 109 ... third insulating layer, 110 ... fourth insulating layer

Abstract

The liquid crystal lens has a liquid crystal layer between a control electrode and a fixed electrode that face each other, and an electrical field is applied between the facing electrodes in order to control the orientation of the liquid crystal molecules of the liquid crystal layer. The control electrode is divided into at least two regions, and the liquid crystal layer is disposed such that the direction of the orientation of the liquid crystal layer does not match the direction of the boundary between the facing control electrodes in the effective area of the lens. Due to this configuration, when the liquid crystal lens having a split electrode is incorporated into a camera or other imaging device, deterioration of the imaging performance can be prevented and good image quality is can be obtained.

Description

液晶レンズ及び撮像装置Liquid crystal lens and imaging device
　近年、高画質なデジタルスチルカメラやデジタルビデオカメラ（以下、デジタルカメラという）が急速に普及してきている。また、最近では携帯電話端末等のモバイル機器に小型で高画質なデジタルカメラが搭載されてきており、デジタルカメラの小型化、薄型化の開発も進められている。このようなデジタルカメラにおいて、撮像素子に像を結像させる光学系は、通常、収差を除去するために、数枚のレンズから構成されている。また、光学的なズーム機能やフォーカス機能を持たせる場合は、組合せレンズの焦点距離や、レンズと撮像素子の間隔を変える駆動機構（アクチュエータ）が必要となる。このように、一部のレンズを移動させ、その位置関係を変化させることで焦点距離または焦点位置を変化させる方法では、機構が複雑になるという点や、可動部が必要になるため耐衝撃性が低いといった点が課題となっている。 In recent years, high-quality digital still cameras and digital video cameras (hereinafter referred to as digital cameras) are rapidly spreading. Recently, small and high-quality digital cameras have been mounted on mobile devices such as mobile phone terminals, and the development of smaller and thinner digital cameras is also underway. In such a digital camera, an optical system for forming an image on an image sensor is usually composed of several lenses in order to eliminate aberrations. In addition, when an optical zoom function or a focus function is provided, a drive mechanism (actuator) that changes the focal length of the combination lens and the distance between the lens and the image sensor is necessary. In this way, in the method of changing the focal length or focal position by moving some lenses and changing their positional relationship, the mechanism is complicated, and because a movable part is required, impact resistance is required. The problem is that it is low.
　そこで、レンズを駆動するための可動機構を用いない合焦点手法として、電圧を印加することで液晶内の屈折率分布を変化させてレンズ効果を得ることができる液晶レンズを用いる方式が知られている。従来の液晶レンズとして、軸対称に配置された制御電極と透明平面電極とを対向に配置し、両電極の間に液晶層を介在させた液晶レンズが提案されている。このような液晶レンズでは電圧が印加された時に、制御電極の中心を軸とする軸対称な電界分布が形成されて液晶層に軸対称な屈折率分布が発生し、それによりレンズ効果を得ることができる。そして、液晶層に印加する電界強度を変化させることで電界分布を可変にして焦点距離を任意に制御することが可能である。 Therefore, as a focusing method that does not use a movable mechanism for driving the lens, a method using a liquid crystal lens that can obtain a lens effect by changing a refractive index distribution in the liquid crystal by applying a voltage is known. Yes. As a conventional liquid crystal lens, there has been proposed a liquid crystal lens in which a control electrode and a transparent flat electrode arranged in an axial symmetry are arranged to face each other and a liquid crystal layer is interposed between the two electrodes. In such a liquid crystal lens, when a voltage is applied, an axially symmetric electric field distribution about the center of the control electrode is formed, and an axially symmetric refractive index distribution is generated in the liquid crystal layer, thereby obtaining a lens effect. Can do. Then, by changing the electric field strength applied to the liquid crystal layer, the electric field distribution can be varied to arbitrarily control the focal length.
　従来の液晶レンズの技術として、同心円状に独立に電圧を印加させることが可能な透明電極帯を有する液晶レンズが知られている（例えば、特許文献１参照）。この液晶レンズでは、レンズの焦点距離はそれぞれの電極帯への印加電圧を制御することによって変化させることができる。 As a conventional liquid crystal lens technology, there is known a liquid crystal lens having a transparent electrode band capable of independently applying a voltage concentrically (see, for example, Patent Document 1). In this liquid crystal lens, the focal length of the lens can be changed by controlling the voltage applied to each electrode band.
　しかしながら、特許文献１に示す液晶レンズのようにリング状の電極を多数配置して構成した液晶レンズでは中心から連続的な電界分布を形成するためには電極帯を細分化する必要があり、制御が困難になるという問題がある。このような問題を解決するために、より簡単な構成として円形の孔部が設けられた孔抜きパターン電極と透明平面電極とを対向に配置し、両電極の間に液晶層を介在させた液晶レンズも提案されている（例えば、特許文献２参照）。これは、円形穴型パターンを有する電極をスリットで分割することで焦点距離だけでなく光軸に垂直な方向へ焦点位置を変えるものである。この液晶レンズでは分割されたそれぞれの電極に異なる電圧を印加して制御することで電極の孔の中心軸に対称であった屈折率分布を非対称な分布とすることができる。これにより入射光に対する偏向効果を生じさせて光軸方向の焦点距離の制御のみだけでなく光軸と垂直な面内においても焦点の位置を変えることができる。 However, in the liquid crystal lens configured by arranging a large number of ring-shaped electrodes like the liquid crystal lens shown in Patent Document 1, it is necessary to subdivide the electrode band in order to form a continuous electric field distribution from the center. There is a problem that becomes difficult. In order to solve such a problem, as a simpler structure, a liquid crystal layer in which a hole pattern electrode provided with a circular hole and a transparent flat electrode are arranged to face each other, and a liquid crystal layer is interposed between both electrodes. A lens has also been proposed (see, for example, Patent Document 2). In this method, an electrode having a circular hole pattern is divided by slits to change not only the focal length but also the focal position in a direction perpendicular to the optical axis. In this liquid crystal lens, by applying different voltages to the divided electrodes and controlling them, the refractive index distribution that is symmetric with respect to the central axis of the hole of the electrode can be made asymmetric. As a result, a deflection effect on the incident light is generated, and the focal position can be changed not only in the control of the focal length in the optical axis direction but also in a plane perpendicular to the optical axis.
特開平０３－００２８４０号公報Japanese Patent Laid-Open No. 03-002840 特開平１１－１０９３０４号公報JP-A-11-109304
　液晶レンズは、その電極に印加する電圧を制御して、液晶レンズ面内の屈折率分布を変化させることにより焦点距離と光軸方向を変えることができるため、撮像光学系への適用が期待されている。従来の液晶レンズを撮像装置用の光学レンズとして用いる場合、目的とする画角に合わせた方向の光線を取り込む必要があるが、液晶レンズの各液晶層はそれぞれ一方向に配向されているので、入射した光線の入射方向や角度によって集光特性に差異が発生する。これは特に配向方向に平行な面内で入射する光線に対して大きな影響が現れる。また、電極が分割された構成の液晶レンズでは、電極の分割された部分での電界分布にひずみが発生し、レンズとしての結像特性に影響を与える要因となる。 Since the liquid crystal lens can change the focal length and the optical axis direction by controlling the voltage applied to its electrode and changing the refractive index distribution in the liquid crystal lens surface, it is expected to be applied to the imaging optical system. ing. When using a conventional liquid crystal lens as an optical lens for an imaging device, it is necessary to capture light in a direction that matches the target angle of view, but each liquid crystal layer of the liquid crystal lens is aligned in one direction, There is a difference in light collection characteristics depending on the incident direction and angle of the incident light beam. This has a great influence on a light ray incident in a plane parallel to the alignment direction. Further, in the liquid crystal lens having a configuration in which the electrode is divided, the electric field distribution in the divided portion of the electrode is distorted, which is a factor that affects the imaging characteristics of the lens.
　図８は、互いに対向する一対の電極６０３ａ、６０３ｂの間に液晶層６０１を有し、電極６０３ａには円形パターンの孔部が設けられた、従来の液晶レンズの断面図を模式的に示している。また、誘電率の観点から液晶分子６０２を略回転楕円体として表すと、図８に示すように、電極間に電圧を印加することで液晶（ネマチック液晶）分子６０２の長軸が電界６０４の向きに沿って配向し、液晶層内の屈折率分布が液晶分子の誘電率に基づいて変化する。このような屈折率変化を利用することで、液晶レンズへの入射光６０３を透過光６０４のように１点に集光させる。しかし、径方向にスリットが入って分割された液晶レンズでは、電極が分割されている部分の近傍は印加される電界が弱いため、液晶分子の傾きが僅かに小さくなり、集光点がずれて結像特性に影響をおよぼす。 FIG. 8 schematically shows a cross-sectional view of a conventional liquid crystal lens in which a liquid crystal layer 601 is provided between a pair of electrodes 603a and 603b facing each other, and a circular pattern hole is provided in the electrode 603a. Yes. Further, when the liquid crystal molecules 602 are expressed as a substantially spheroid from the viewpoint of dielectric constant, the major axis of the liquid crystal (nematic liquid crystal) molecules 602 is oriented in the direction of the electric field 604 by applying a voltage between the electrodes as shown in FIG. And the refractive index distribution in the liquid crystal layer changes based on the dielectric constant of the liquid crystal molecules. By utilizing such a refractive index change, the incident light 603 to the liquid crystal lens is condensed at one point like the transmitted light 604. However, in a liquid crystal lens that is divided with slits in the radial direction, the applied electric field is weak in the vicinity of the part where the electrode is divided, so the tilt of the liquid crystal molecules is slightly reduced, and the condensing point is shifted. Affects imaging characteristics.
　図９は液晶レンズの断面方向から見た（配向方向の面で分割した）液晶分子６０２を模式的に示しているが、液晶分子６０２に対する光の入射方向（図９に示す（１）の略回転楕円体の短軸方向、（２）の長軸方向）によって屈折率が異なるため、光線の入射する角度や方向によって異なった特性を示す。このような光線の入射方向や角度の違いによる結像への影響は電極が分割されている近傍のように電解の弱い部分でより顕著に現れる。また、図１０は電界方向（光軸方向）から見た液晶分子を模式的に示しているが、同一の平面上で同じ入射角かつ対称に入射する２光線を考えた場合、液晶の配向方向（１）－（２）の平面上での２光線に対する屈折率差に比べて、入射方向が（１）'－（２）'のように配向方向からの角度が大きい平面上での２光線に対する屈折率差の方が小さくなる。 FIG. 9 schematically shows the liquid crystal molecules 602 as viewed from the cross-sectional direction of the liquid crystal lens (divided by the plane of the alignment direction). Since the refractive index varies depending on the minor axis direction of the spheroid and the major axis direction of (2), different characteristics are exhibited depending on the incident angle and direction of the light beam. The influence on the image formation due to the difference in the incident direction and angle of the light beam appears more conspicuously in a portion where electrolysis is weak, such as in the vicinity where the electrode is divided. FIG. 10 schematically shows the liquid crystal molecules viewed from the electric field direction (optical axis direction). However, when two light beams incident on the same plane and with the same incident angle are considered, the alignment direction of the liquid crystal. Compared to the difference in refractive index for two rays on the plane (1)-(2), the two rays on the plane whose incident direction is a large angle from the orientation direction, such as (1) '-(2)'. The refractive index difference with respect to becomes smaller.
　したがって、円形パターン電極にスリットが入った構造の液晶レンズを撮像レンズとして用いる場合において、電極の分割部分の近傍が結像特性に影響を与え、その影響はレンズの光軸に対して非対称となる。撮像レンズはある一定の画角の光線を取り込む必要があるため、液晶レンズへの入射角が大きくなるほどその非対称性は大きくなり、補正も困難になる。特に、電極の分割方向が液晶層（液晶分子）の配向方向と一致した場合には、その近傍での結像特性を大きく劣化させると共にその非対称性も大きくなる。すなわち、撮像レンズとして用いた場合にムラの大きな結像特性を持つレンズとなってしまうという問題がある。 Therefore, when a liquid crystal lens having a slit in a circular pattern electrode is used as an imaging lens, the vicinity of the divided portion of the electrode affects the imaging characteristics, and the influence is asymmetric with respect to the optical axis of the lens. . Since the imaging lens needs to capture a light beam having a certain angle of view, as the incident angle to the liquid crystal lens increases, the asymmetry increases and correction becomes difficult. In particular, when the electrode dividing direction coincides with the alignment direction of the liquid crystal layer (liquid crystal molecules), the imaging characteristics in the vicinity thereof are greatly degraded and the asymmetry is also increased. That is, when used as an imaging lens, there is a problem that the lens has a large imaging characteristic.
　本発明は、このような事情に鑑みてなされたもので、結像性能の低下を防ぎ、非対称性を改善すると共に良好な画質が得られる液晶レンズとそれを用いた撮像装置を提供することを目的とする。 The present invention has been made in view of such circumstances, and it is intended to provide a liquid crystal lens capable of preventing deterioration in imaging performance, improving asymmetry and obtaining good image quality, and an imaging apparatus using the liquid crystal lens. Objective.
　本発明は、互いに対向する制御電極と固定電極との間に液晶層を有し、前記対向する電極間に電圧を印加することにより前記液晶層の液晶分子の配向制御を行う液晶レンズであって、前記制御電極は少なくとも２つの領域に分割され、前記液晶層の配向方向はレンズ有効領域内において、対向する前記制御電極同士の境界の方向と一致しないことを特徴とする。 The present invention is a liquid crystal lens having a liquid crystal layer between a control electrode and a fixed electrode facing each other, and controlling the alignment of liquid crystal molecules of the liquid crystal layer by applying a voltage between the facing electrodes. The control electrode is divided into at least two regions, and the alignment direction of the liquid crystal layer does not coincide with the direction of the boundary between the opposing control electrodes in the lens effective region.
　本発明は、前記制御電極は、孔を有する孔抜き電極であり、前記境界により孔の径方向に分割され、各電極には独立に電圧を印加することを特徴とする。 The present invention is characterized in that the control electrode is a punched electrode having a hole, and is divided in the radial direction of the hole by the boundary, and a voltage is applied to each electrode independently.
　本発明は、前記液晶層の配向方向と、前記対向する制御電極同士の境界の方向とが最大角をなすことを特徴とする。 The present invention is characterized in that the alignment direction of the liquid crystal layer and the direction of the boundary between the opposing control electrodes form a maximum angle.
　本発明は、制御電極と、それに対向するようにその両側に設けられた固定電極との間にそれぞれ液晶層を有し、前記対向する電極間に電圧を印加することにより前記液晶層の液晶分子の配向制御を行う液晶レンズであって、前記制御電極は少なくとも２つの領域に分割され、前記液晶層の配向方向はレンズ有効領域内において、対向する前記制御電極同士の境界の方向と一致しないことを特徴とする。 The present invention has a liquid crystal layer between a control electrode and fixed electrodes provided on both sides of the control electrode so as to face each other, and a voltage is applied between the facing electrodes to thereby form liquid crystal molecules in the liquid crystal layer. The control electrode is divided into at least two regions, and the orientation direction of the liquid crystal layer does not coincide with the direction of the boundary between the opposing control electrodes in the lens effective region. It is characterized by.
　本発明は、前記制御電極は、孔を有する孔抜き電極であり、前記境界により孔の径方向に分割され、各電極には独立に電圧を印加することを特徴とする。 The present invention is characterized in that the control electrode is a punched electrode having a hole, and is divided in the radial direction of the hole by the boundary, and a voltage is applied to each electrode independently.
　本発明は、前記液晶層の配向方向と、前記対向する制御電極同士の境界の方向とが最大角をなすことを特徴とする。 The present invention is characterized in that the alignment direction of the liquid crystal layer and the direction of the boundary between the opposing control electrodes form a maximum angle.
　本発明は、前記２つの液晶層の配向方向は垂直であること特徴とする。 The present invention is characterized in that the alignment directions of the two liquid crystal layers are vertical.
　本発明は、請求項１～７のいずれかに記載の液晶レンズと、撮像素子と、前記液晶レンズに印加する電圧を制御することにより前記撮像素子に入射する光の光軸の方向を制御する光軸制御部とを備えることを特徴とする。 The present invention controls the direction of the optical axis of light incident on the image pickup device by controlling the voltage applied to the liquid crystal lens according to any one of claims 1 to 7, the image pickup device, and the liquid crystal lens. And an optical axis control unit.
　本発明によれば、分割された制御電極を有する液晶レンズにおいて、電極分割箇所における光線の集光特性劣化の影響を低減し結像特性を改善することが可能になるという効果が得られる。
　また、本発明による液晶レンズを撮像装置に組込むことで、光軸調整可能であり、高画質な画像を撮像することが可能になるという効果が得られる。 According to the present invention, in the liquid crystal lens having the divided control electrodes, it is possible to reduce the influence of the deterioration of the light converging characteristics of the light rays at the electrode dividing positions and to improve the imaging characteristics.
In addition, by incorporating the liquid crystal lens according to the present invention into an imaging device, the optical axis can be adjusted, and an effect that it is possible to capture a high-quality image can be obtained.
本発明の第１の実施形態における液晶レンズ１００の構成を示す正面図である。It is a front view which shows the structure of the liquid crystal lens 100 in the 1st Embodiment of this invention. 本発明の第１の実施形態における液晶レンズ１００の構成を示す断面図である。It is sectional drawing which shows the structure of the liquid crystal lens 100 in the 1st Embodiment of this invention. 図１に示す電極１０４ａ、１０４ｂ、１０４ｃ、１０４ｄと液晶分子の配向方向の関係を示す説明図である。It is explanatory drawing which shows the relationship between the electrode 104a, 104b, 104c, 104d shown in FIG. 1, and the orientation direction of a liquid crystal molecule. 本発明の第２の実施形態における液晶レンズ１００の構成を示す正面図である。It is a front view which shows the structure of the liquid crystal lens 100 in the 2nd Embodiment of this invention. 本発明の第２の実施形態における液晶レンズ１００の構成を示す断面図である。It is sectional drawing which shows the structure of the liquid-crystal lens 100 in the 2nd Embodiment of this invention. 本発明の第３の実施形態における撮像装置の全体構成を示す機能ブロック図である。It is a functional block diagram which shows the whole structure of the imaging device in the 3rd Embodiment of this invention. 本発明の第４の実施形態における撮像装置の全体構成を示す機能ブロック図である。It is a functional block diagram which shows the whole structure of the imaging device in the 4th Embodiment of this invention. 液晶分子と屈折率の関係を示す説明図である。It is explanatory drawing which shows the relationship between a liquid crystal molecule and a refractive index. 液晶分子と屈折率の関係を示す説明図である。It is explanatory drawing which shows the relationship between a liquid crystal molecule and a refractive index. 液晶分子と屈折率の関係を示す説明図である。It is explanatory drawing which shows the relationship between a liquid crystal molecule and a refractive index.
　以下、本発明の実施形態による液晶レンズ及び撮像装置を図面を参照して説明する。
＜第１の実施形態＞
　図１、２は第１の実施形態における液晶レンズ１００の構成を示す正面図とＡ－Ａ'断面図である。液晶レンズ１００は、透明な第１の電極１０３、第２の電極１０４、透明な第３の電極１０５、第２の電極１０４と第３の電極１０５との間に配置された液晶層１０６、第１の電極１０３と第２の電極１０４との間に配置された第１の絶縁層１０７、第２の電極１０４と第３の電極１０５の間に配置された第２の絶縁層１０８、第１の電極１０３の外側に配置された第３の絶縁層１０９、第３の電極１０５の外側に配置された第４の絶縁層１１０によって構成されている。なお、電極１０３、電極１０５はそれぞれ透明な光透過性を有する材料で構成されている。また、上述の電極及び絶縁体はそれぞれ透明な光透過性を有する材料で構成されている。 Hereinafter, a liquid crystal lens and an imaging apparatus according to embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
1 and 2 are a front view and a cross-sectional view taken along line AA ′ showing the configuration of the liquid crystal lens 100 according to the first embodiment. The liquid crystal lens 100 includes a transparent first electrode 103, a second electrode 104, a transparent third electrode 105, a liquid crystal layer 106 disposed between the second electrode 104 and the third electrode 105, The first insulating layer 107 disposed between the first electrode 103 and the second electrode 104; the second insulating layer 108 disposed between the second electrode 104 and the third electrode 105; The third insulating layer 109 is disposed outside the third electrode 103, and the fourth insulating layer 110 is disposed outside the third electrode 105. Note that the electrode 103 and the electrode 105 are each made of a transparent material having light transmittance. Moreover, the above-mentioned electrode and insulator are each comprised with the material which has transparent light transmittance.
　第２の電極１０４は、円形の孔１０４ｅを有しており、図１の正面図に示すように縦、横に分割された４つの電極１０４ａ、１０４ｂ、１０４ｃ、１０４ｄによって構成されている（これを孔抜き電極という）。それぞれの電極１０４ａ、１０４ｂ、１０４ｃ、１０４ｄに対して独立して電圧を印加することができる。そして、液晶層１０６を挟む電極１０３、１０４、１０５の間に電圧を印加して液晶分子の配向制御を行うことにより、第２の電極１０４で構成する円形の孔１０４ｅ内（これがレンズ有効領域となる）の液晶層１０６の屈折率分布が変化して、光学レンズとして機能する。 The second electrode 104 has a circular hole 104e and is composed of four electrodes 104a, 104b, 104c, and 104d that are divided vertically and horizontally as shown in the front view of FIG. Is referred to as a punched electrode). A voltage can be applied independently to each of the electrodes 104a, 104b, 104c, and 104d. Then, by applying a voltage between the electrodes 103, 104, and 105 sandwiching the liquid crystal layer 106 to control the alignment of the liquid crystal molecules, the inside of the circular hole 104e formed by the second electrode 104 (this corresponds to the lens effective region). The refractive index distribution of the liquid crystal layer 106 changes to function as an optical lens.
　ここで、電極１０４の分割方向のうち、縦方向の分割方向を符号１４０ａの線分で示し、横方向の分割方向を符号１４０ｂの線分で示す。液晶層１０６においては、液晶分子を一方向に配向させており、その配向方向を符号１３０の線分で示す。液晶層１０６は、線分１３０の方向（液晶分子の配向方向）が、対向する２つの電極（電極１０４ａと１０４ｂ、電極１０４ｂと１０４ｄ、電極１０４ａと１０４ｃ、電極１０４ｃと１０４ｄ）同士の境界の方向（線分１４０ａ、１４０ｂの方向）と一致しない方向になるように配置されている。 Here, among the division directions of the electrode 104, the vertical division direction is indicated by a line segment 140a, and the horizontal division direction is indicated by a line segment 140b. In the liquid crystal layer 106, liquid crystal molecules are aligned in one direction, and the alignment direction is indicated by a line segment 130. In the liquid crystal layer 106, the direction of the line segment 130 (the alignment direction of liquid crystal molecules) is the direction of the boundary between two electrodes ( electrodes 104a and 104b, electrodes 104b and 104d, electrodes 104a and 104c, electrodes 104c and 104d) facing each other. They are arranged in a direction that does not match (the direction of the line segments 140a and 140b).
　液晶分子の配向方向（線分１３０）は、２つの電極同士の境界方向と一致せずに、かつ液晶分子の配向方向と電極同士の境界方向とのなす角度が最大になる方向とすることが望ましい。すなわち、４分割の電極では、２つの境界方向（２つの線分１４０ａ、１４０ｂ）が交差してなす角度を２分する角度とするのが望ましい。図１に示す例では、線分１４０ａと１４０ｂがなす角度が９０°であるので、２つの線分１４０ａと１４０ｂのそれぞれと線分１３０とのなす角度は４５°となる。この例は、４分割電極の場合であるが、２分割の電極である場合は、分割方向と配向方向とのなす角度が９０°となる。また、８分割電極である場合は、分割方向と配向方向とのなす角度が２２．５°となる。 The alignment direction of the liquid crystal molecules (line segment 130) does not coincide with the boundary direction between the two electrodes, and the direction between the alignment direction of the liquid crystal molecules and the boundary direction between the electrodes is maximized. desirable. In other words, in the case of four-divided electrodes, it is desirable that the angle formed by the two boundary directions (two line segments 140a and 140b) intersect is divided into two. In the example shown in FIG. 1, since the angle formed by the line segments 140a and 140b is 90 °, the angle formed by each of the two line segments 140a and 140b and the line segment 130 is 45 °. This example is a case of a four-divided electrode, but in the case of a two-divided electrode, the angle formed by the dividing direction and the orientation direction is 90 °. Further, in the case of an 8-divided electrode, the angle formed by the dividing direction and the alignment direction is 22.5 °.
　一例として液晶レンズ１００の寸法を以下に示す。第２の電極１０４の円形の孔１０４ｅのサイズは約φ２ｍｍであり、第１の電極１０３との間隔は７０μｍであり、第２の絶縁層１０８の厚みは７００μｍである。液晶層１０６の厚さは６０μｍとしている。また、液晶層１０６の配向方向１３０は分割電極１０４の分割方向１４０ａ、１４０ｂとそれぞれ４５度をなす方向であり、電極の分割方向１４０ａ、１４０ｂと液晶の配向方向のなす角が最大となるような配置としている。このような配置とすることで電極の分割箇所における電界のひずみによる集光特性への影響と液晶の配向方向における集光特性への影響を分散させることが可能であり、レンズの結像特性を改善することが可能である。また、絶縁層１０８は大口径化のため例えば７００μｍの厚さの透明な硝子等を用いている。２つの対向する電極（電極１０４ａと１０４ｂ、電極１０４ｂと１０４ｄ、電極１０４ａと１０４ｃ、電極１０４ｃと１０４ｄ）同士の境界部分の距離は、放電が発生しない状態を保つことができる最短距離とすることが望ましい。 As an example, the dimensions of the liquid crystal lens 100 are shown below. The size of the circular hole 104e of the second electrode 104 is about φ2 mm, the distance from the first electrode 103 is 70 μm, and the thickness of the second insulating layer 108 is 700 μm. The thickness of the liquid crystal layer 106 is 60 μm. In addition, the alignment direction 130 of the liquid crystal layer 106 is a direction that forms 45 degrees with the dividing directions 140a and 140b of the divided electrode 104, respectively, and the angle formed by the dividing directions 140a and 140b of the electrode and the alignment direction of the liquid crystal is maximized. It is arranged. With such an arrangement, it is possible to disperse the influence on the light condensing characteristics due to the distortion of the electric field at the electrode division location and the influence on the light condensing characteristics in the alignment direction of the liquid crystal. It is possible to improve. The insulating layer 108 is made of, for example, a transparent glass having a thickness of 700 μm in order to increase the diameter. The distance at the boundary between the two opposing electrodes ( electrodes 104a and 104b, electrodes 104b and 104d, electrodes 104a and 104c, and electrodes 104c and 104d) should be the shortest distance that can maintain a state in which no discharge occurs. desirable.
　また、本実施の形態では第１の電極１０３と第２の電極１０４は異なった層となっているが、同一の面上に形成しても構わない。その場合、第１の電極１０３の形状は第２の電極１０４の円形の孔１０４ｅよりも小さなサイズの円形として第２の電極１０４の孔１０４ｅの位置に配置し、第２の電極１０４の分割部分のスリットに電極取り出し部を設けた構成とする。このとき、第１の電極１０３と第２の電極を構成する電極１０４ａ、１０４ｂ、１０４ｃ、１０４ｄはそれぞれ独立に電圧制御が行える。このような構成をすることで全体の厚みを減少させることができる。 In this embodiment mode, the first electrode 103 and the second electrode 104 are different layers, but they may be formed on the same surface. In that case, the shape of the first electrode 103 is a circle having a smaller size than the circular hole 104e of the second electrode 104, and is arranged at the position of the hole 104e of the second electrode 104. It is set as the structure which provided the electrode extraction part in the slit of this. At this time, the electrodes 104a, 104b, 104c, and 104d constituting the first electrode 103 and the second electrode can be independently voltage controlled. With this configuration, the overall thickness can be reduced.
　次に、図１、２に示す液晶レンズ１００の動作を説明する。図１、２に示す液晶レンズ１００において、透明な第３の電極１０５とアルミニウム薄膜等で構成された第２の電極１０４との間に電圧を印加すると同時に、第１の電極１０３と第２の電極１０４の間にも電圧を印加することにより、円形の孔１０４ｅを有する第２の電極１０４の中心軸１２０に軸対象な電界勾配を形成することができる。このように形成された円形電極のエッジ周りの軸対象な電界勾配により、液晶層１０６の細長い略回転楕円体の形状をした液晶（一例としてネマチック液晶）分子がその長軸を電界方向に向けて配向する。その結果、液晶層１０６の配向分布の変化により、異常光の屈折率分布が円形の電極の中心から周辺まで変化するため、レンズとして機能させることができる。第１の電極１０３、第２の電極１０４への電圧の掛け方によってこの液晶層１０６の屈折率分布を自由に変化させることができ、凸レンズや凹レンズなど自由に光学的な特性の制御を行うことが可能である。 Next, the operation of the liquid crystal lens 100 shown in FIGS. In the liquid crystal lens 100 shown in FIGS. 1 and 2, a voltage is applied between the transparent third electrode 105 and the second electrode 104 made of an aluminum thin film or the like, and at the same time, the first electrode 103 and the second electrode By applying a voltage between the electrodes 104 as well, it is possible to form an axial electric field gradient on the central axis 120 of the second electrode 104 having the circular hole 104e. Due to the electric field gradient around the edge of the circular electrode formed in this way, the liquid crystal (e.g., nematic liquid crystal) molecule in the shape of an elongated spheroid of the liquid crystal layer 106 has its long axis directed in the direction of the electric field. Orient. As a result, the refractive index distribution of the extraordinary light changes from the center to the periphery of the circular electrode due to the change in the orientation distribution of the liquid crystal layer 106, so that it can function as a lens. The refractive index distribution of the liquid crystal layer 106 can be freely changed by applying a voltage to the first electrode 103 and the second electrode 104, and optical characteristics such as a convex lens and a concave lens can be freely controlled. Is possible.
　本実施形態では、第１の電極１０３と第３の電極１０５の間に２０Ｖｒｍｓの実効電圧を印加し、また、第２の電極１０４と第３の電極１０５の間に７０Ｖｒｍｓの実効電圧を印加して凸レンズとして機能させている。凸レンズとして機能させる場合にはこのように第１の電極１０３に印加する電圧が第２の電極１０４に印加する電圧より小さくすればよい。また、レンズの焦点距離を変更する場合には第1の電極１０３に印加する電圧を制御すればよい。ここで、液晶駆動電圧（各電極間に印加する電圧）は正弦波、またはデューティ比５０％の矩形波の交流波形である。印加する電圧値は実効電圧（ｒｍｓ：自乗平均平方根）で表す。例えば１００Ｖｒｍｓの交流正弦波は、±１４４Ｖの尖頭値を有する電圧波形となる。また、交流電圧の周波数は例えば１ｋＨｚが用いられる。 In this embodiment, an effective voltage of 20 Vrms is applied between the first electrode 103 and the third electrode 105, and an effective voltage of 70 Vrms is applied between the second electrode 104 and the third electrode 105. And function as a convex lens. In the case of functioning as a convex lens, the voltage applied to the first electrode 103 may be made smaller than the voltage applied to the second electrode 104 in this way. In addition, when changing the focal length of the lens, the voltage applied to the first electrode 103 may be controlled. Here, the liquid crystal driving voltage (voltage applied between the electrodes) is a sine wave or a rectangular wave AC waveform with a duty ratio of 50%. The voltage value to be applied is represented by an effective voltage (rms: root mean square). For example, an AC sine wave of 100 Vrms has a voltage waveform having a peak value of ± 144V. Further, for example, 1 kHz is used as the frequency of the AC voltage.
　ここでは凸レンズとして機能させる場合について示したが、凹レンズとして機能させる場合には、例えば第１の電極１０３と第３の電極１０５の間に９０Ｖｒｍｓの実効電圧を印加し、また、第２の電極１０４と第３の電極１０５の間に３０Ｖｒｍｓの実効電圧を印加するなど、第１の電極への印加電圧が第２の電極への印加電圧より大きくなるように制御すればよい。 Here, the case of functioning as a convex lens is shown, but when functioning as a concave lens, for example, an effective voltage of 90 Vrms is applied between the first electrode 103 and the third electrode 105, and the second electrode 104 is used. For example, an effective voltage of 30 Vrms may be applied between the first electrode and the third electrode 105 so that the applied voltage to the first electrode is higher than the applied voltage to the second electrode.
　さらに第２の電極１０４を構成する電極１０４ａ、１０４ｂ、１０４ｃ、１０４ｄと第３の電極１０５との間にそれぞれ異なった電圧を印加することにより、同一電圧を印加したときには軸対称であった屈折率分布が、円形の孔１０４ｅを有する第２の電極中心軸１２０に対して、軸のずれた非対称な分布となり、入射光が直進する方向から偏向するという効果が得られる。この場合、分割された第２の電極１０４と第３の電極１０５の間に印加する電圧を適宜変えることにより、入射光の偏向の方向を変化させることができる。例えば、電極１０４ａと電極１０５間と、電極１０４ｃと電極１０５間にそれぞれ７５Ｖｒｍｓを、電極１０４ｂと電極１０５間と、電極１０４ｄと電極１０５間にそれぞれ７０Ｖｒｍｓを印加することで、符号１２０で示す光軸位置が符号１２１で示す位置にシフトする。そのシフト量は例えば４０μｍである。 Further, by applying different voltages between the electrodes 104a, 104b, 104c, and 104d constituting the second electrode 104 and the third electrode 105, the refractive index was axially symmetric when the same voltage was applied. The distribution is an asymmetric distribution with the axis shifted with respect to the second electrode central axis 120 having the circular hole 104e, and the effect that the incident light is deflected from the straight traveling direction is obtained. In this case, the direction of incident light deflection can be changed by appropriately changing the voltage applied between the divided second electrode 104 and the third electrode 105. For example, by applying 75 Vrms between the electrode 104 a and the electrode 105, between the electrode 104 c and the electrode 105, and between the electrode 104 b and the electrode 105, and 70 Vrms between the electrode 104 d and the electrode 105, respectively, The position is shifted to the position indicated by reference numeral 121. The shift amount is 40 μm, for example.
　なお、液晶層１０６の液晶分子の配向方向は、２つの電極同士の境界の方向と一致しない方向であれば、液晶分子の配向方向（線分１３０）は、液晶分子の配向方向と電極同士の境界方向とのなす角度が最大になる方向に限るものではない。図３に示すように、第２の電極１０４の円形の孔１０４ｅの中心点Ｐ１と、４つの電極１０４ａ、１０４ｂ、１０４ｃ、１０４ｄの８つの端点Ｐ２～Ｐ９のそれぞれとを結ぶ８本の線分１４１～１４８の方向を除く方向を液晶層１０６の液晶分子の配向方向とすればよい。すなわち、線分１４１～線分１４８の方向、線分１４２～線分１４３の方向、線分１４４～線分１４５の方向及び線分１４６～線分１４７の方向を除けば、電極分割箇所における光線の集光特性劣化の影響を低減し結像特性の改善することができる。 If the alignment direction of the liquid crystal molecules in the liquid crystal layer 106 is a direction that does not coincide with the direction of the boundary between the two electrodes, the alignment direction of the liquid crystal molecules (segment 130) is the same as the alignment direction between the liquid crystal molecules and the electrodes. It is not limited to the direction in which the angle formed with the boundary direction is maximized. As shown in FIG. 3, eight line segments connecting the center point P1 of the circular hole 104e of the second electrode 104 and each of the eight end points P2 to P9 of the four electrodes 104a, 104b, 104c, and 104d. The direction excluding the directions 141 to 148 may be the alignment direction of the liquid crystal molecules of the liquid crystal layer 106. That is, the light rays at the electrode division points are excluded except for the direction of the line segment 141 to the line segment 148, the direction of the line segment 142 to the line segment 143, the direction of the line segment 144 to the line segment 145, and the direction of the line segment 146 to the line segment 147. It is possible to reduce the influence of the deterioration of the light condensing characteristics and improve the imaging characteristics.
　このように液晶レンズ１００は、第２の電極（制御電極）１０４の分割方向と液晶層１０６の配向方向を一致させない配置とした構造のため、液晶レンズ１００の円形の孔１０４ｅ内に入射する角度を持った光に対する集光特性が改善され、像のぼけを低減することができる。 As described above, the liquid crystal lens 100 has a structure in which the division direction of the second electrode (control electrode) 104 and the alignment direction of the liquid crystal layer 106 are not aligned with each other, and therefore, the incident angle into the circular hole 104e of the liquid crystal lens 100. Therefore, the light condensing characteristic with respect to the light having the light is improved, and the blur of the image can be reduced.
　また、本実施例では液晶層は１層で構成されているが、これに限るものではない。液晶層を複数の層で構成することにより、強いレンズパワーを得ることが可能となる。さらに同じレンズパワーを薄い液晶層の組合せで構成できるので動作速度の改善が可能となる。また、偏光方向を変えた組合せにすることで入射光の偏光方向に関係なくレンズ効果を得ることも可能になる。 In this embodiment, the liquid crystal layer is composed of a single layer, but the present invention is not limited to this. By configuring the liquid crystal layer with a plurality of layers, it is possible to obtain a strong lens power. Furthermore, since the same lens power can be constituted by a combination of thin liquid crystal layers, the operation speed can be improved. In addition, a lens effect can be obtained regardless of the polarization direction of incident light by combining the polarization directions.
＜第２の実施形態＞
　図４、５は、第２の実施の形態に係る液晶レンズ２００の構成を示す正面図とＢ－Ｂ'断面図である。本実施形態における液晶レンズ２００は、透明な第１の電極２０３、不透明な第２の電極２０４、透明な第３の電極２０５ａ、２０５ｂ、第２の電極２０４と第３の電極２０５ａ（２０５ｂ）との間に配置された液晶層２０６ａ（２０６ｂ）、第２の電極２０４と第３の電極２０５ａ（２０５ｂ）の間に配置された第２の絶縁層２０８ａ（２０８ｂ）、第３の電極２０５ａ（２０５ｂ）の外側に配置された第４の絶縁層２１０ａ（２１０ｂ）によって構成されている。 <Second Embodiment>
4 and 5 are a front view and a BB ′ sectional view showing the configuration of the liquid crystal lens 200 according to the second embodiment. The liquid crystal lens 200 in the present embodiment includes a transparent first electrode 203, an opaque second electrode 204, transparent third electrodes 205a and 205b, a second electrode 204, and a third electrode 205a (205b). Liquid crystal layer 206a (206b) disposed between the second electrode 204 and the second insulating layer 208a (208b) disposed between the second electrode 204 and the third electrode 205a (205b), and the third electrode 205a (205b). ), The fourth insulating layer 210a (210b).
　ここで、第２の電極２０４は、円形の孔を有しており、図４の正面図に示すように縦、横に分割された４つの電極２０４ａ、２０４ｂ、２０４ｃ、２０４ｄによって構成されており、それぞれの電極に独立して電圧を印加することができる。ここで電極２０４の分割された方向をそれぞれ電極分割方向線分２４０ａ、２４０ｂで示す。また、第１の電極２０３は第２の電極２０４の孔の中心位置に配置されており、電極２０４ｂと２０４ｄの間のスリットの部分に電極の引き出し線２０３ａ、２０３ｂを設けており、この引き出し線から電極２０３に対して電圧が印加される。第１の電極２０３と、第２の電極を構成する電極２０４ａ、２０４ｂ、２０４ｃ、２０４ｄのそれぞれは、独立に電圧制御を行うことが可能である。液晶層２０６ａ１、２０６ａ２と液晶層２０６ｂ１、２０６ｂ２はそれぞれ２層の液晶層から構成されており、液晶層２０６ａ１、２０６ｂ１と液晶層２０６ａ２、２０６ｂ２は同じ偏光方向となるように配置している。また、液晶層２０６ａ１（２０６ｂ１）と２０６ａ２（２０６ｂ２）は、互いに異なる方向の配向となるように配置している。液晶レンズ２００では液晶層２０６ａ１、２０６ａ２、２０６ｂ１、２０６ｂ２へ入射する光線の角度や方向により集光特性に影響が発生し、特に配向方向に平行な面内での特性差は大きいが、電極の分割方向と互いの液晶層の配向方向を異なる方向にして配置することによって集光特性の改善を図ることができる。 Here, the second electrode 204 has a circular hole, and is composed of four electrodes 204a, 204b, 204c, and 204d divided vertically and horizontally as shown in the front view of FIG. The voltage can be applied independently to each electrode. Here, the divided direction of the electrode 204 is indicated by electrode dividing direction line segments 240a and 240b, respectively. The first electrode 203 is arranged at the center position of the hole of the second electrode 204, and electrode lead lines 203a and 203b are provided in a slit portion between the electrodes 204b and 204d. A voltage is applied to the electrode 203. Each of the first electrode 203 and the electrodes 204a, 204b, 204c, and 204d constituting the second electrode can be independently voltage controlled. The liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 are each composed of two liquid crystal layers, and the liquid crystal layers 206a1 and 206b1 and the liquid crystal layers 206a2 and 206b2 are arranged to have the same polarization direction. Further, the liquid crystal layers 206a1 (206b1) and 206a2 (206b2) are arranged so as to be aligned in different directions. In the liquid crystal lens 200, the condensing characteristics are affected by the angle and direction of light rays incident on the liquid crystal layers 206a1, 206a2, 206b1, and 206b2, and there is a large difference in characteristics in a plane parallel to the alignment direction. The condensing characteristics can be improved by disposing the liquid crystal layers in different directions from each other.
　また、液晶層２０６ａ１（２０６ｂ１）と、２０６ａ２（２０６ｂ２）は偏光方向が９０度となるようにとなるように配置している。液晶層２０６ａ１（２０６ｂ１）と、液晶層２０６ａ２（２０６ｂ２）はそれぞれ１偏光方向の光にのみしかレンズ効果を満たせないが、このように液晶層２０６ａ１（２０６ｂ１）と、液晶層２０６ａ２（２０６ｂ２）の偏光方向を９０度となるように配置することで全ての偏光方向の光に対してレンズ効果を得ることができる。それぞれの液晶の配向制御は液晶層２０６ａ１、２０６ａ２（２０６ｂ１、２０６ｂ２）を挟む電極２０３、２０４、２０５の間に電圧を印加することで液晶層２０６ａ１、２０６ａ２と、液晶層２０６ｂ１、２０６ｂ２の液晶分子の配向制御を行う。ここで、液晶層２０６ａ１、２０６ｂ１は配向方向が線分２３０方向の一方の方向（矢印の方向）となるように配置し、液晶層２０６ａ２、２０６ｂ２は配向方向が線分２３１方向の一方の方向（矢印の方向）となるように配置している。線分２３０、２３１は共に電極分割方向線分２４０ａ、２４０ｂと一致しない配置となっている。 The liquid crystal layers 206a1 (206b1) and 206a2 (206b2) are arranged so that the polarization direction is 90 degrees. Each of the liquid crystal layer 206a1 (206b1) and the liquid crystal layer 206a2 (206b2) can satisfy the lens effect only for light in one polarization direction, and thus the polarization of the liquid crystal layer 206a1 (206b1) and the liquid crystal layer 206a2 (206b2). By arranging the direction to be 90 degrees, it is possible to obtain a lens effect for light in all polarization directions. The orientation of each liquid crystal is controlled by applying a voltage between the electrodes 203, 204, and 205 sandwiching the liquid crystal layers 206a1 and 206a2 (206b1 and 206b2), and the liquid crystal molecules in the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2. Alignment control is performed. Here, the liquid crystal layers 206a1 and 206b1 are arranged so that the alignment direction is one direction of the line segment 230 (direction of the arrow), and the liquid crystal layers 206a2 and 206b2 are one direction of the alignment direction of the line segment 231 ( (Direction of arrow). Both the line segments 230 and 231 are arranged so as not to coincide with the electrode dividing direction line segments 240a and 240b.
　ここでは液晶層２０６ａ１、２０６ｂ１と液晶層２０６ａ２、２０６ｂ２がそれぞれ同じ配光方向となるように配置したが、液晶層２０６ａ１、２０６ａ２と液晶層２０６ｂ１、２０６ｂ２がそれぞれ同じ配光方向となるようにしてもよい。ただし、この場合、２つの偏光方向での焦点位置のずれが大きくなるため、電極２０４と電極２０５ａとの電位差が電極２０４と電極２０５ｂとの電位差よりも小さくなるように制御する必要がある。 Here, the liquid crystal layers 206a1 and 206b1 and the liquid crystal layers 206a2 and 206b2 are arranged to have the same light distribution direction, but the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 may be arranged to have the same light distribution direction. Good. However, in this case, since the shift of the focal position in the two polarization directions becomes large, it is necessary to control so that the potential difference between the electrode 204 and the electrode 205a is smaller than the potential difference between the electrode 204 and the electrode 205b.
　一例として液晶レンズ２００の寸法を以下に示す。第２の電極２０４の円形の孔のサイズは約φ３ｍｍであり、絶縁層２０８ａ（２０８ｂ）の厚みは７００μｍである。液晶層２０６の厚さは３０μｍとしている。また、液晶層２０６ａ、２０６ｂの配向方向線分２３０、２３１のそれぞれは電極分割方向線分２４０ａ、２４０ｂのそれぞれと４５度をなす方向であり、電極の分割方向と液晶層２０６ａ１、２０６ａ２と液晶層２０６ｂ１、２０６ｂ２の配向方向のなす角が最大となるような配置としている。また、絶縁層２０８ａ（２０８ｂ）は大口径化のため例えば７００μｍの厚さの透明な硝子等を用いている。このような配置とすることで電極の分割箇所における電界のひずみによる集光特性への影響と液晶の配向方向における集光特性への影響を分散させることが可能であり、レンズの結像特性を改善することが可能である。 As an example, the dimensions of the liquid crystal lens 200 are shown below. The size of the circular hole of the second electrode 204 is about φ3 mm, and the thickness of the insulating layer 208a (208b) is 700 μm. The thickness of the liquid crystal layer 206 is 30 μm. Further, the alignment direction line segments 230 and 231 of the liquid crystal layers 206a and 206b are directions that form 45 degrees with the electrode division direction line segments 240a and 240b, respectively. The electrode division direction, the liquid crystal layers 206a1 and 206a2, and the liquid crystal layer The arrangement is such that the angle formed by the orientation directions of 206b1 and 206b2 is maximized. The insulating layer 208a (208b) is made of, for example, a transparent glass having a thickness of 700 μm for the purpose of increasing the diameter. With such an arrangement, it is possible to disperse the influence on the light condensing characteristics due to the distortion of the electric field at the electrode division location and the influence on the light condensing characteristics in the alignment direction of the liquid crystal. It is possible to improve.
　次に、図４、５に示す液晶レンズ２００の動作を説明する。各液晶層２０６ａ１、２０６ａ２と液晶層２０６ｂ１、２０６ｂ２における動作に関しては第１の実施形態で説明した動作と同様に、透明な第３の電極２０５ａ（２０５ｂ）とアルミニウム薄膜等で構成された第２の電極２０４との間に電圧を印加すると同時に、第１の電極２０３と第２の電極２０４の間にも電圧を印加することにより、円形の孔を有する第２の電極２０４の中心軸２２０に軸対象な電界勾配を形成することができる。このように形成された円形電極のエッジ周りの軸対象な電界勾配により、液晶層２０６ａ１、２０６ａ２と液晶層２０６ｂ１、２０６ｂ２の液晶分子が電界勾配の方向に配向し、レンズとして機能させることができる。第１の電極２０３、第２の電極２０４への電圧の掛け方によってこの液晶層２０６ａ１、２０６ａ２と液晶層２０６ｂ１、２０６ｂ２の屈折率分布を自由に変化させることができ、凸レンズや凹レンズなど自由に光学的な特性の制御を行うことが可能である。また、電極２０４ａ、２０４ｂ、２０４ｃ、２０４ｄと第３の電極２０５との間にそれぞれ異なった電圧を印加することにより、同一電圧を印加したときには軸対称であった屈折率分布が、円形の孔を有する第２の電極中心軸２２０に対して、軸のずれた非対称な分布となり、入射光が直進する方向から偏向するという効果が得られ、焦点位置を光軸に垂直な面内で制御が可能である。 Next, the operation of the liquid crystal lens 200 shown in FIGS. As for the operation in each of the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2, as in the operation described in the first embodiment, a second electrode composed of a transparent third electrode 205a (205b) and an aluminum thin film is used. By applying a voltage between the first electrode 203 and the second electrode 204 at the same time as applying a voltage between the electrode 204 and the center axis 220 of the second electrode 204 having a circular hole, A target electric field gradient can be formed. Due to the axial target electric field gradient around the edge of the circular electrode formed in this way, the liquid crystal molecules of the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 are aligned in the direction of the electric field gradient and can function as a lens. The refractive index distribution of the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 can be freely changed by applying a voltage to the first electrode 203 and the second electrode 204. Characteristic control can be performed. Further, by applying different voltages between the electrodes 204a, 204b, 204c, and 204d and the third electrode 205, the refractive index distribution that is axially symmetric when the same voltage is applied becomes a circular hole. The second electrode central axis 220 has an asymmetrical distribution with the axis shifted, and the effect that the incident light is deflected from the straight traveling direction can be obtained, and the focal position can be controlled in a plane perpendicular to the optical axis. It is.
　このように液晶レンズ２００は、制御電極２０４の分割方向とレンズを構成する全ての液晶層２０６ａ１、２０６ａ２と液晶層２０６ｂ１、２０６ｂ２の配向方向を一致させない配置とした構造のため、液晶レンズ２００に入射する角度を持った光に対する集光特性が改善され、像のぼけを低減することができる。 As described above, the liquid crystal lens 200 has a structure in which the dividing direction of the control electrode 204 and the alignment directions of all the liquid crystal layers 206a1 and 206a2 and the liquid crystal layers 206b1 and 206b2 constituting the lens do not coincide with each other. Therefore, the light condensing characteristic with respect to the light having the angle to be improved is improved, and the blur of the image can be reduced.
＜第３の実施形態＞
　次に、図６を参照して、本発明による液晶レンズを用いた撮像装置を説明する。図６は、本発明の第３の実施形態に係る撮像装置の全体構成を示す機能ブロック図である。図６において、２００は液晶レンズである。図６において、第２の実施形態における液晶レンズ２００と同一の部分は同一の符号を付して、その応用例も含めて説明を一部省略し、簡単に説明する。なお、電極の分割方向と液晶層の配置方向による結像特性の劣化低減に関しても第２の実施形態の説明と同様である。 <Third Embodiment>
Next, an image pickup apparatus using the liquid crystal lens according to the present invention will be described with reference to FIG. FIG. 6 is a functional block diagram showing an overall configuration of an imaging apparatus according to the third embodiment of the present invention. In FIG. 6, reference numeral 200 denotes a liquid crystal lens. In FIG. 6, the same parts as those of the liquid crystal lens 200 in the second embodiment are denoted by the same reference numerals, and a part of the description including application examples thereof will be omitted. Note that the reduction in image formation characteristics due to the electrode dividing direction and the liquid crystal layer arranging direction is the same as that described in the second embodiment.
　図６の撮像装置３００は、撮像部３１０、液晶レンズへの印加電圧を制御する制御部３０３、撮像素子からの信号を映像信号へと変換する映像処理部３０５によって構成され、撮像部３１０はさらに撮像素子３０４と撮像素子３０４に像を結像させる撮像レンズ３０２を備えている。ここで、撮像レンズ３０２は第２の実施形態において説明した４分割された制御電極と４層の液晶層を備えた液晶レンズ２００とガラスによる光学レンズ３０１との組合せによって構成されている。本実施形態では液晶レンズ２００を用いたがこれに限定せず、分割された電極を有し、かつ電極の分割方向と液晶層の配向方向が一致しないように配置した液晶レンズであれば何でもよい。また、光学レンズ３０１は他にもプラスチックなどから構成されたものでもよく、撮像レンズとしての組み合わせ方は特に本実施形態に限定しない。例えば、ガラスレンズの間に液晶レンズを挿入した構成とし、ガラスレンズによって液晶レンズへの入射光の入射角度を抑えるような配置としてもよい。この場合、液晶レンズへの入射角度が低減されるためより光学特性のよい撮像レンズを実現できる。 The imaging apparatus 300 in FIG. 6 includes an imaging unit 310, a control unit 303 that controls the voltage applied to the liquid crystal lens, and a video processing unit 305 that converts a signal from the imaging device into a video signal. An image pickup element 302 that forms an image on the image pickup element 304 and the image pickup element 304 is provided. Here, the imaging lens 302 is configured by a combination of the liquid crystal lens 200 including the four divided control electrodes and the four liquid crystal layers described in the second embodiment, and the optical lens 301 made of glass. In the present embodiment, the liquid crystal lens 200 is used. However, the present invention is not limited to this, and any liquid crystal lens may be used as long as it has divided electrodes and is arranged so that the dividing direction of the electrodes does not coincide with the alignment direction of the liquid crystal layer. . In addition, the optical lens 301 may be made of plastic or the like, and the combination as an imaging lens is not particularly limited to this embodiment. For example, a configuration in which a liquid crystal lens is inserted between glass lenses and the incident angle of incident light on the liquid crystal lens is suppressed by the glass lens may be employed. In this case, since the incident angle to the liquid crystal lens is reduced, an imaging lens with better optical characteristics can be realized.
　制御部３０３は、液晶レンズ２００に印加する電圧を制御する電圧制御部３０３ａ、３０３ｂ、３０３ｃ、３０３ｄから構成されている。制御部３０３の電圧制御部３０３ａ、３０３ｂ、３０３ｃ、３０３ｄのそれぞれは、液晶レンズ２００内に備える制御電極２０４ａ、２０４ｂ、２０４ｃ、２０４ｄそれぞれの印加電圧を制御する。 The control unit 303 includes voltage control units 303a, 303b, 303c, and 303d that control the voltage applied to the liquid crystal lens 200. Each of the voltage control units 303a, 303b, 303c, and 303d of the control unit 303 controls the applied voltage of each of the control electrodes 204a, 204b, 204c, and 204d provided in the liquid crystal lens 200.
　次に動作について簡単に説明する。撮像レンズ３０２は撮影対象からの光を対応する撮像素子３０４上に結像する。撮像レンズ３０２よって結像されたイメージを撮像素子３０４で光電変換し、光信号を電気信号に変換する。撮像素子３０４で変換された電気信号は映像処理部３０５で、予め設定されたパラメータ等により映像信号を変換する。この映像信号をもとに制御部３０３は最適な焦点位置となるように液晶レンズ２００の制御電極２０４ａ、２０４ｂ、２０４ｃ、２０４ｄに対して電圧を印加する。例えば、結像位置がずれていれば光軸の方向を変えるように制御電極２０４ａ、２０４ｂ、２０４ｃ、２０４ｄに対して電圧を印加する。ここで光軸シフトは例えば、電極２０４ａ、２０４ｃへの印加電圧を電極２０４ｂ、２０４よりも大きな値とした場合に、撮像素子３０４に対して電極２０４ａ、２０４ｃ側へ光軸がシフトする。つまり、光軸をシフトさせたい方向の電圧が高いように印加電圧を制御すればよい。また、焦点位置がずれていれば（像がぼけていれば）焦点位置を変化させるように制御電極２０３への印加電圧を制御する。この制御は焦点位置を遠くにする場合には印加電圧値を高くし、逆に焦点位置を近づけるに従い印加電圧を小さくする。 Next, the operation will be briefly explained. The imaging lens 302 forms an image of light from a subject to be imaged on the corresponding imaging element 304. An image formed by the imaging lens 302 is photoelectrically converted by the imaging element 304, and an optical signal is converted into an electrical signal. The electric signal converted by the image sensor 304 is converted by the video processing unit 305 using a preset parameter or the like. Based on this video signal, the control unit 303 applies a voltage to the control electrodes 204a, 204b, 204c, and 204d of the liquid crystal lens 200 so as to obtain an optimum focal position. For example, a voltage is applied to the control electrodes 204a, 204b, 204c, and 204d so as to change the direction of the optical axis if the imaging position is deviated. Here, for example, when the voltage applied to the electrodes 204a and 204c is larger than that of the electrodes 204b and 204, the optical axis shifts toward the electrodes 204a and 204c with respect to the imaging element 304. That is, the applied voltage may be controlled so that the voltage in the direction in which the optical axis is desired to be shifted is high. If the focal position is deviated (if the image is blurred), the voltage applied to the control electrode 203 is controlled so as to change the focal position. In this control, the applied voltage value is increased when the focal position is far away, and conversely, the applied voltage is decreased as the focal position is brought closer.
　このように、液晶レンズ２００は電圧の制御のみで光軸方向だけではなく光軸に垂直な面内においても自由に焦点位置を制御することが可能であり、焦点合わせに駆動機構の必要がない。そのため、撮像装置３００は簡単な構造でサイズの小型化も可能である。また、制御電極の分割方向と全ての液晶層の配向方向を一致させない配置とした構造となっているため結像性能の劣化を抑制し、良好な画質を得ることができる撮像装置を実現できる。 Thus, the liquid crystal lens 200 can control the focal position freely not only in the optical axis direction but also in a plane perpendicular to the optical axis only by controlling the voltage, and there is no need for a driving mechanism for focusing. . Therefore, the imaging apparatus 300 can be reduced in size with a simple structure. In addition, since the arrangement is such that the dividing direction of the control electrode and the alignment direction of all the liquid crystal layers do not coincide with each other, it is possible to realize an imaging device capable of suppressing deterioration in imaging performance and obtaining good image quality.
＜第４の実施形態＞
　次に、図７を参照して、本発明による液晶レンズを用いた他の撮像装置を説明する。図７は、本発明の実施形態に係る撮像装置４００の全体構成を示す機能ブロック図である。本実施形態では第３の実施形態において説明した撮像装置３００を複数個（この例では４個）組み合わせて構成した多眼の撮像装置である。図７において、第３の実施形態における撮像装置３００と同一の部分は同一の符号を付して、その応用例も含めて説明を一部省略し、簡単に説明する。なお、電極の分割方向と液晶層の配置方向による結像特性の劣化低減に関しても第２の実施形態の説明と同様である。 <Fourth Embodiment>
Next, with reference to FIG. 7, another imaging apparatus using the liquid crystal lens according to the present invention will be described. FIG. 7 is a functional block diagram showing the overall configuration of the imaging apparatus 400 according to the embodiment of the present invention. The present embodiment is a multi-lens imaging device configured by combining a plurality of imaging devices 300 described in the third embodiment (four in this example). In FIG. 7, the same parts as those of the image pickup apparatus 300 in the third embodiment are denoted by the same reference numerals, and a part of the description including the application examples thereof will be omitted and briefly described. Note that the reduction in image formation characteristics due to the electrode dividing direction and the liquid crystal layer arranging direction is the same as that described in the second embodiment.
　図７に示す撮像装置４００は、４系統の撮像部３１０ａ、３１０ｂ、３１０ｃ、３１０ｄから構成された撮像装置の一例である。撮像部３１０ａは撮像レンズ３０２と撮像素子３０４から構成されており、撮像部３１０ｂ、３１０ｃ、３１０ｄの構成も同様である。４つの撮像部３１０ａ、３１０ｂ、３１０ｃ、３１０ｄは、撮影対象を撮像して、４系統の画像信号を出力する。以下、１つの撮像部３１０ａを例にとり、画像信号の流れを説明する。撮像レンズ３０２よって結像された画像を撮像素子３０４で光電変換し、光信号を電気信号に変換する。撮像素子３０４で変換された電気信号は映像処理部３０５１で、予め設定されたパラメータ等により映像信号を変換する。映像処理部３０５１で変換された映像信号は、映像合成部４０１に入る。同時に、他の撮像部３１０ｂ、３１０ｃ、３１０ｄからの画像信号は、対応する各映像処理部３０５２、３０５３、３０５４で変換処理されて映像合成処理部４０１に入力される。 The imaging apparatus 400 shown in FIG. 7 is an example of an imaging apparatus that includes four systems of imaging units 310a, 310b, 310c, and 310d. The imaging unit 310a includes an imaging lens 302 and an imaging element 304, and the configurations of the imaging units 310b, 310c, and 310d are the same. The four imaging units 310a, 310b, 310c, and 310d capture an imaging target and output four systems of image signals. Hereinafter, the flow of an image signal will be described by taking one imaging unit 310a as an example. An image formed by the imaging lens 302 is photoelectrically converted by the imaging element 304, and an optical signal is converted into an electrical signal. The electrical signal converted by the image sensor 304 is converted by the video processing unit 3051 according to preset parameters or the like. The video signal converted by the video processing unit 3051 enters the video composition unit 401. At the same time, image signals from the other imaging units 310 b, 310 c, and 310 d are converted by the corresponding video processing units 3052, 3053, and 3054 and input to the video composition processing unit 401.
　映像合成処理部４０１は、４系統の撮像部３１０ａ、３１０ｂ、３１０ｃ、３１０ｄで撮像された４つの映像信号を同期を取りながら１つの映像信号に合成し、高精細映像として出力する。また映像合成処理部４０１では、合成された高解像度映像が予め設定した判定値より劣化していた場合は、その判定結果に基づいて、制御信号を生成する。その制御信号に基づいて、各制御部３０３１～３０３４は、対応する各撮像レンズ３０２の光軸制御を行い、再度、映像合成処理部４０１で判定する。判定結果が良ければ高精細映像を出力し、悪ければ再度、撮像レンズ３０２を制御することにより高精細映像を出力する。 The video composition processing unit 401 synthesizes the four video signals captured by the four image capturing units 310a, 310b, 310c, and 310d into one video signal while synchronizing them, and outputs it as a high-definition video. The video composition processing unit 401 generates a control signal based on the determination result when the combined high-resolution video is deteriorated from a predetermined determination value. Based on the control signal, each of the control units 3031 to 3034 performs optical axis control of the corresponding imaging lens 302, and the video composition processing unit 401 determines again. If the determination result is good, a high-definition video is output, and if it is bad, the imaging lens 302 is controlled again to output a high-definition video.
　なお、本実施形態では４つの撮像部３００ａ～３００ｄを備えた４眼構成であったが、数に限定はなく５眼や６眼、それ以上でも構わない。例えば、緑フィルタを備えた撮像部４個と赤と青のフィルタを備えた撮像部をそれぞれ１個組み合わせた６眼構成とすることで、緑の撮像部により高精細化を行い、それに赤と青の撮像部からの映像信号を合成処理して高精細なカラー画像を得るようにしてもよい。このような手法により感度の良い撮像装置を実現でき、明るく画質の良い画像を得ることができる。 In the present embodiment, the four-eye configuration includes four imaging units 300a to 300d. However, the number is not limited, and five or six eyes or more may be used. For example, by adopting a 6-lens configuration in which four image pickup units having a green filter and one image pickup unit having a red and blue filter are combined, the green image pickup unit achieves high definition, A high-definition color image may be obtained by synthesizing the video signal from the blue imaging unit. An imaging device with high sensitivity can be realized by such a method, and a bright and good image quality can be obtained.
　また、本発明の撮像装置４００では液晶レンズ２００は電圧の制御のみで光軸方向だけではなく光軸に垂直な面内においても自由に焦点位置を制御することが可能であるため、焦点合わせに駆動機構の必要がなく、簡単な構造でサイズの小型化も可能である。また、液晶レンズは制御電極の分割方向と全ての液晶層の配向方向を一致させない配置とした構造となっているため結像性能の劣化を抑制し、良好な画質を得ることができる撮像装置を実現できる。 In the imaging apparatus 400 of the present invention, the liquid crystal lens 200 can freely control the focal position not only in the optical axis direction but also in a plane perpendicular to the optical axis only by controlling the voltage. There is no need for a drive mechanism, and the size can be reduced with a simple structure. In addition, since the liquid crystal lens has a structure in which the dividing direction of the control electrode and the alignment direction of all the liquid crystal layers do not coincide with each other, an image pickup apparatus capable of suppressing deterioration in imaging performance and obtaining good image quality is provided. realizable.
　以上説明したように、少なくとも２つの領域に分割された制御電極を備える液晶レンズ有効領域内において、対向する制御電極同士の境界の方向と一致しないように液晶層の配向方向を決めるようにしたため、制御電極の境界部分近傍における光線の集光特性劣化の影響を低減し結像特性を改善することが可能になる。また、この液晶レンズを撮像装置に組込むことで、高精度な光軸調整可能になり、高画質な画像を撮像することが可能になる。 As described above, in the liquid crystal lens effective region including the control electrode divided into at least two regions, the orientation direction of the liquid crystal layer is determined so as not to coincide with the direction of the boundary between the opposing control electrodes. It is possible to reduce the influence of the deterioration of the light condensing characteristic of the light beam in the vicinity of the boundary portion of the control electrode and improve the imaging characteristic. Further, by incorporating this liquid crystal lens into the image pickup apparatus, it becomes possible to adjust the optical axis with high accuracy and to pick up a high-quality image.
　液晶を用いて光学レンズを構成することが不可欠な用途に適用できる。 It can be applied to applications where it is indispensable to construct optical lenses using liquid crystals.
　１００・・・液晶レンズ、１０３・・・第１の電極、１０４・・・第２の電極、１０５・・・第３の電極、１０６・・・液晶層１０６、１０７・・・第１の絶縁層、１０８・・・第２の絶縁層、１０９・・・第３の絶縁層、１１０・・・第４の絶縁層 DESCRIPTION OF SYMBOLS 100 ... Liquid crystal lens, 103 ... 1st electrode, 104 ... 2nd electrode, 105 ... 3rd electrode, 106 ... Liquid crystal layer 106, 107 ... 1st insulation Layer, 108 ... second insulating layer, 109 ... third insulating layer, 110 ... fourth insulating layer

Claims (8)

  1. 　互いに対向する制御電極と固定電極との間に液晶層を有し、前記対向する電極間に電圧を印加することにより前記液晶層の液晶分子の配向制御を行う液晶レンズであって、
    　前記制御電極は少なくとも２つの領域に分割され、前記液晶層の配向方向はレンズ有効領域内において、対向する前記制御電極同士の境界の方向と一致しないことを特徴とする液晶レンズ。     A liquid crystal lens having a liquid crystal layer between a control electrode and a fixed electrode facing each other, and controlling alignment of liquid crystal molecules of the liquid crystal layer by applying a voltage between the facing electrodes,
    The liquid crystal lens, wherein the control electrode is divided into at least two regions, and the alignment direction of the liquid crystal layer does not coincide with the direction of the boundary between the opposing control electrodes in the lens effective region.
  2. 　前記制御電極は、孔を有する孔抜き電極であり、前記境界により孔の径方向に分割され、各電極には独立に電圧を印加することを特徴とする請求項１に記載の液晶レンズ。 The liquid crystal lens according to claim 1, wherein the control electrode is a holed electrode having a hole, and is divided in a radial direction of the hole by the boundary, and a voltage is independently applied to each electrode.
  3. 　前記液晶層の配向方向と、前記対向する制御電極同士の境界の方向とが最大角をなすことを特徴とする請求項１または２のいずれかに記載の液晶レンズ。 3. The liquid crystal lens according to claim 1, wherein the alignment direction of the liquid crystal layer and the direction of the boundary between the opposed control electrodes form a maximum angle.
  4. 　制御電極と、それに対向するようにその両側に設けられた固定電極との間にそれぞれ液晶層を有し、前記対向する電極間に電圧を印加することにより前記液晶層の液晶分子の配向制御を行う液晶レンズであって、
    　前記制御電極は少なくとも２つの領域に分割され、前記液晶層の配向方向はレンズ有効領域内において、対向する前記制御電極同士の境界の方向と一致しないことを特徴とする液晶レンズ。     Each of the liquid crystal layers has a liquid crystal layer between the control electrode and a fixed electrode provided on both sides of the control electrode, and the liquid crystal molecules in the liquid crystal layer are aligned by applying a voltage between the opposing electrodes. A liquid crystal lens to perform,
    The liquid crystal lens, wherein the control electrode is divided into at least two regions, and the alignment direction of the liquid crystal layer does not coincide with the direction of the boundary between the opposing control electrodes in the lens effective region.
  5. 　前記制御電極は、孔を有する孔抜き電極であり、前記境界により孔の径方向に分割され、各電極には独立に電圧を印加することを特徴とする請求項４に記載の液晶レンズ。 The liquid crystal lens according to claim 4, wherein the control electrode is a punched electrode having a hole, and is divided in a radial direction of the hole by the boundary, and a voltage is independently applied to each electrode.
  6. 　前記液晶層の配向方向と、前記対向する制御電極同士の境界の方向とが最大角をなすことを特徴とする請求項４または５のいずれかに記載の液晶レンズ。 6. The liquid crystal lens according to claim 4, wherein the alignment direction of the liquid crystal layer and the direction of the boundary between the opposed control electrodes form a maximum angle.
  7. 　前記２つの液晶層の配向方向は垂直であること特徴とする請求項４から６のいずれかに記載の液晶レンズ。 7. The liquid crystal lens according to claim 4, wherein the alignment direction of the two liquid crystal layers is vertical.
  8. 　請求項１～７のいずれかに記載の液晶レンズと、撮像素子と、前記液晶レンズに印加する電圧を制御することにより前記撮像素子に入射する光の光軸の方向を制御する光軸制御部とを備えることを特徴とする撮像装置。 The liquid crystal lens according to any one of claims 1 to 7, an image sensor, and an optical axis controller that controls a direction of an optical axis of light incident on the image sensor by controlling a voltage applied to the liquid crystal lens. An imaging apparatus comprising:
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