Optical element and optical device equipped with the same

Abstract

To provide an optical element which has a sufficiently large variable power region, exhibits less distortion in an electrically inactive state and offers good visibility, and to provide an optical device having the same.SOLUTION: An optical element provided herein is capable of switching between the first and second states with different focal lengths and comprises a first electrode layer, insulating layer, resistive layer, liquid crystal layer, and second electrode layer arranged in the described order, where electrical resistivity of the resistive layer at a first point is different from that at a second point.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to an optical element and an optical apparatus including the same. [Background technology]

[0002] Patent document 1 discloses an electroactive element (liquid crystal lens) that can add optical power to the power section for presbyopia when the user views a distant object, but can add optical power to the power section for presbyopia when the user views a close object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2011-516927 Summary of the Invention [Problem to be solved by the invention]

[0004] The liquid crystal lens of Patent Document 1 is constructed by disposing a variable power region in a portion of a progressive power lens with a smoothly changing curvature. Therefore, when the lens is electrically inactive, the view appears distorted when the user looks at a distant object, which is undesirable. Furthermore, since a diffraction grating must be formed on the substrate glass, it is difficult to enlarge the variable power region.

[0005] An object of the present invention is to provide an optical element having a sufficiently wide variable power region and exhibiting low distortion and good visibility in an electrically inactivated state, and an optical apparatus including the same. [Means for solving the problem]

[0006] An optical element according to one aspect of the present invention comprises: , th In direction 1 array was Multiple electrode and , disposed on the plurality of electrodes in a second direction perpendicular to the first direction. Insulation layer and , disposed on the insulating layer in the second direction. resistance layer and , disposed on the resistive layer in the second direction. Liquid crystal layer and , disposed above the liquid crystal layer in the second direction. electrode layer and and an optical element that, in an electrically activated state, is switchable between a first state and a second state having different focal lengths in response to a change in voltage applied to the plurality of electrodes, The electrical resistivity of the resistive layer is 2 perpendicular to the direction of cross section in Optical elements It grows larger from the center to the periphery. When the electrical resistivity of the insulating layer is R1 and the electrical resistivity of each region in the first direction of the resistive layer is R2, 1×10 -7 <R2 / R1<1×10 -3 The conditional expression It is characterized by: [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an optical element having a sufficiently wide variable power region, little distortion in an electrically inactivated state, and good visibility, and an optical apparatus including the same. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of electronic eyeglasses, which is an example of an optical device including an optical element according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the electronic glasses. [Figure 3] FIG. 1 is a diagram illustrating the configuration of electronic glasses. [Figure 4] FIG. 1 is a front view of an electro-active lens. [Figure 5] 3A and 3B are diagrams showing a cross-sectional view of a variable power region and an optical phase difference distribution in a first state. [Figure 6] 10A and 10B are diagrams showing a cross-sectional view of a variable power region and an optical phase difference distribution in a second state. [Figure 7] FIG. 4 is an explanatory diagram of a control method for a variable power region in a first state. [Figure 8] FIG. 10 is an explanatory diagram of a control method for the variable power region in the second state. [Figure 9] FIG. 2 is an explanatory diagram of a method for producing a first electrode layer. [Figure 10]FIG. 2 is a diagram showing the orientation distribution of liquid crystal molecules in a first state. [Figure 11] FIG. 4 is a diagram showing an optical phase difference distribution occurring in a liquid crystal layer in a first state. [Figure 12] FIG. 10 is a diagram showing the orientation distribution of liquid crystal molecules in a second state. [Figure 13] FIG. 10 is a diagram showing an optical phase difference distribution occurring in the liquid crystal layer in the second state. [Figure 14] 10 is a diagram showing another example of the orientation distribution of liquid crystal molecules in the first state. FIG. [Figure 15] 10 is a diagram showing another example of the optical phase difference distribution occurring in the liquid crystal layer in the first state. FIG. [Figure 16] FIG. 4 is a diagram showing the orientation distribution of liquid crystal molecules in a first state (comparative example). [Figure 17] FIG. 4 is a diagram showing an optical phase difference distribution occurring in a liquid crystal layer in a first state (comparative example). DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0010] Fig. 1 is a perspective view of electronic glasses 10, which is an example of an optical device including an optical element according to an embodiment of the present invention. Fig. 2 is a front view of the electronic glasses 10. Fig. 3 is a diagram showing the configuration of the electronic glasses 10.

[0011] The electronic eyeglasses 10 include electro-active lenses (optical elements) 11 and 12, a frame 13, and temples 14 and 15. The electro-active lenses 11 and 12 are liquid crystal lenses with variable focus capabilities. The electro-active lens 11 is for the right eye and includes a variable power region 101. The electro-active lens 12 is for the left eye and includes a variable power region 102. The frame 13 holds the electro-active lenses 11 and 12 and includes a cable 16 connected to the electro-active lenses 11 and 12. The temples 14 and 15 are connected to the frame 13 and include sensors 21 and 22, controllers (controllers) 31 and 32, and power supplies 41 and 42. The sensors 21 and 22, controllers 31 and 32, and power supplies 41 and 42 are electrically connected to the cable 16. The controller units 31 and 32 control the voltages applied to the electro-active lenses 11 and 12 in response to signals from the sensor units 21 and 22, respectively. The optical state of the electro-active lenses 11 and 12 (variable power regions 101 and 102) can be changed by the controller units 31 and 32 controlling the voltages applied to the electro-active lenses 11 and 12. Here, the optical state refers to the optical power (focal length) of the variable power regions 101 and 102.

[0012] In this embodiment, the electro-active lenses 11 and 12 can be switched between a state in which optical power (e.g., +2D) is added to the variable power regions 101 and 102 (electrically activated state) and a state in which substantially no optical power is added (electrically deactivated state). Therefore, in the electronic eyeglasses 10, no optical power is added to each variable power region when the user views a distant object, and optical power is added to each variable power region when the user views a near object. This eliminates regions with different optical powers within the electro-active lenses 11 and 12 in the electrically deactivated state, achieving a uniform power distribution. In other words, the electronic eyeglasses 10 (electro-active lenses 11 and 12) can be realized with less distortion and better visibility in the electrically deactivated state.

[0013] In this embodiment, the electro-active lenses 11 and 12 can be switched between a first state and a second state having different focal lengths in an electrically activated state. Specifically, the electro-active lenses 11 and 12 can be switched between a first state in which the variable power regions 101 and 102 have a first optical power and a second state in which the variable power regions have a second optical power smaller than the first optical power in an electrically activated state. For example, each variable power region has, for example, +2D in the first state and, for example, +1D in the second state. That is, in this embodiment, the first optical power is twice the second optical power. Therefore, in the electronic eyeglasses 10, the first optical power is applied to each variable power region when the user views a near area, and the second optical power is applied to each variable power region when the user views an intermediate area, for example, a distance from a monitor when using a personal computer. By changing the optical power added to each variable power region in this way, it is possible to realize electronic eyeglasses 10 (electro-active lenses 11, 12) that can focus on both the near and intermediate ranges.

[0014] FIG. 4 is a front view of electro-active lens 11. The outer shape of electro-active lens 11 is processed to correspond to the shape of frame 13. Furthermore, the front and rear surfaces of electro-active lens 11 are processed to correspond to the user's desired power of correction. Variable power region 101 is formed on the user's nose side from the center of electro-active lens 11. Variable power region 101 has optically transparent annular electrodes 1, 2, 3, and 4 arranged concentrically. Annular electrodes 1, 2, 3, and 4 are connected to lead wires 51, 52, 53, and 54, respectively. Each lead wire extends to the outer periphery of electro-active lens 11 and is electrically connected to cable 16.

[0015] Hereinafter, with reference to Figs. 5 to 8, a control method for each variable power region when switching each electro-active lens between a first state and a second state will be described. Fig. 5 is a diagram showing a cross-sectional view of the variable power region 101 (102) in the first state and an optical phase difference distribution. Fig. 6 is a diagram showing a cross-sectional view of the variable power region 101 (102) in the second state and an optical phase difference distribution. Fig. 7 is an explanatory diagram of a control method for the variable power region 101 (102) in the first state. Fig. 8 is an explanatory diagram of a control method for the variable power region 101 (102) in the second state.

[0016] 5A is a structural diagram (cross-sectional view) of the variable power region 101 (102) in a first state. The variable power region 101 (102) is sandwiched between a first substrate having a flat surface or a surface with a constant curvature and a second substrate having a flat surface or a surface with a constant curvature.

[0017] The variable power region 101 comprises a first electrode layer, an insulating layer 6, a resistive layer 7, a liquid crystal layer 8, and a second electrode layer 5, arranged in that order.

[0018] The first electrode layer includes ring electrodes 1, 2, 3, and 4. The second electrode layer 5 is an optically transparent single electrode layer. The first electrode layer and the second electrode layer 5 are made of, for example, a transparent conductive oxide (ITO, titanium oxide, zinc oxide, or a mixture thereof) or a conductive organic material (PEDOT:PSS or carbon nanotubes).

[0019] The insulating layer 6 is optically transparent and is provided between the first electrode layer and the resistive layer 7 to electrically insulate the annular electrodes. The insulating layer 6 is made of, for example, silicon dioxide (SiO2). The thickness of the insulating layer 6 is preferably 0.01 μm or more and 1 μm or less. The electrical resistivity of the insulating layer 6 is 1×10 8 Ω cm or more 1×10 12 It is preferable that the resistivity is Ω·cm or less.

[0020] The resistive layer 7 is optically transparent and is provided between the insulating layer 6 and the liquid crystal layer 8. By providing the resistive layer 7, it becomes possible to smoothly change the voltage between the ring electrodes to which voltages of different magnitudes are applied. The resistive layer 7 is made of, for example, a transparent conductive oxide (e.g., zinc oxide) or a conductive organic material (e.g., PEDOT:PSS or carbon nanotubes). The thickness of the resistive layer 7 is preferably 0.01 μm or more and 1 μm or less. The electrical resistivity of the resistive layer 7 is 1×10 2 Ω cm or more 1×10 7 It is preferable that the resistivity is Ω·cm or less.

[0021] The liquid crystal layer 8 is provided between the resistance layer 7 and the second electrode layer 5. The orientation distribution of the liquid crystal layer 8 can be adjusted by controlling the voltage applied to the first electrode layer and the second electrode layer 5 using the controller unit 31 (32). Adjusting the orientation distribution of the liquid crystal layer 8 makes it possible to impart a desired optical retardation distribution to incident light.

[0022] An alignment film (not shown) is provided so as to be in contact with the liquid crystal layer 8. The alignment film is a thin film made of, for example, a polyimide material. The thickness of the alignment film is preferably 0.1 μm or less. The alignment film is subjected to a rubbing treatment or a photo-alignment treatment in which linearly polarized ultraviolet light is irradiated onto the alignment film. This allows the initial alignment of the liquid crystal molecules inside the liquid crystal layer 8 to be controlled.

[0023] In this embodiment, when the electrical resistivity of the insulating layer 6 is R1 and the electrical resistivity of the resistive layer 7 is R2, it is preferable that the following conditional expression (1) be satisfied.

[0024] 1×10 -7 <R2 / R1<1×10 -3 (1) By satisfying conditional expression (1), the area of ​​the variable power region 101 (102) can be made sufficiently large. If the upper limit of conditional expression (1) is exceeded, the potential distribution across the liquid crystal layer 8 will not have a Fresnel lens shape or a diffractive lens shape, and a smooth refractive index distribution will not be imparted to the liquid crystal layer 8, which is undesirable. If the lower limit of conditional expression (1) is exceeded, the absolute value of the potential across the liquid crystal layer 8 will be too small, and a sufficient refractive index distribution will not be imparted to the liquid crystal layer 8, which is undesirable.

[0025] It is also preferable that the numerical range of conditional expression (1) be within the range of the following conditional expression (1a).

[0026] 5×10 -7 <R2 / R1<5×10 -4 (1a) It is more preferable that the numerical range of conditional expression (1) satisfies the range of the following conditional expression (1b).

[0027] 1×10 -6 <R2 / R1<1×10 -4 (1b) FIG. 5(B) shows the optical phase difference distribution generated in the liquid crystal layer 8 in the first state. By providing an optical phase difference distribution with a Fresnel lens shape or a diffractive lens shape, it is possible to reduce the thickness of the liquid crystal layer 8. To obtain an optical phase difference distribution with a Fresnel lens shape or a diffractive lens shape, the ring electrodes 1, 2, 3, and 4 are arranged concentrically. The size of each ring electrode is determined by the shape of the optical phase difference distribution. The distance (radius) rn from the center of each ring electrode to the position where the optical phase difference switches is expressed by the following equation (2).

[0028] rn=n 1 / 2 ×r1 (2) Here, r1 is the distance from the center of each ring electrode to the closest position to the center of each ring electrode among the positions where the optical phase difference is switched, and n is an integer of 2 or more.

[0029] The ring electrodes 1, 2, 3, and 4 form a pair of ring electrodes, and are arranged so that the position where the optical phase difference switches is located between the pair of ring electrodes. In this embodiment, the ring electrodes 1 and 2 and the ring electrodes 3 and 4 form a pair of ring electrodes. Of the positions where the optical phase difference switches, the position closest to the center of each ring electrode is located between the ring electrodes 3 and 4, and the position second closest to the center of each ring electrode is located between the ring electrodes 1 and 2.

[0030] The controller unit 31 (32) controls the voltage applied to each ring electrode in response to a signal from the sensor unit 21 (22). In the first state, a first voltage V1 is applied to ring electrodes 1 and 3, and a second voltage V2 different from the first voltage V1 is applied to ring electrodes 2 and 4. At this time, the switch unit SW1 is controlled to apply the first voltage V1 to ring electrode 3, and the switch unit SW2 is controlled to apply the second voltage V2 to ring electrode 4. This makes it possible to obtain the optical phase difference distribution shown in FIG. 5(B).

[0031] Fig. 6(A) is a diagram showing the configuration of variable power regions 101 (102) 101 in the second state. Fig. 6(B) is a diagram showing the optical phase difference distribution occurring in liquid crystal layer 8 in the second state.

[0032] In the second state, similar to the first state, a first voltage V1 is applied to the ring electrode 1, and a second voltage V2 is applied to the ring electrode 2. Furthermore, a third voltage V3 is applied to the ring electrode 3, and a fourth voltage V4 is applied to the ring electrode 4. At this time, the switch SW1 is controlled so that the third voltage V3 is applied to the ring electrode 3, and the switch SW2 is controlled so that the fourth voltage V4 is applied to the ring electrode 4. This makes it possible to obtain the optical phase difference distribution shown in FIG. 6(B).

[0033] In this embodiment, the third voltage V3 and the fourth voltage V4 are set to be approximately equal to the average value (=V1+V2 / 2) of the first voltage V1 and the second voltage V2. That is, such a voltage (=(V1+V2) / 2) is applied to a pair of annular electrodes arranged at positions where the subscript n of the distance rn from the center of each annular electrode to the position where the optical phase difference switches, expressed in equation (1), is an odd number. As a result, in the second state, it is possible to obtain an optical phase difference distribution in which the switching pitch of the optical phase difference is twice as large as that in the first state.

[0034] A method for fabricating the first electrode layer will be described below with reference to FIG. 9. FIG. 9 is an explanatory diagram of the method for fabricating the first electrode layer. First, as shown in FIG. 9(A), a uniform electrode layer is formed on a glass substrate using vapor deposition or sputtering. Next, as shown in FIG. 9(B), the uniform electrode layer is patterned into concentric ring shapes by etching to form ring electrodes 1, 2, 3, and 4. Next, as shown in FIG. 9(C), a uniform insulating layer 6 is formed on the ring electrodes 1, 2, 3, and 4 by vapor deposition or sputtering. Next, as shown in FIG. 9(D), rectangular openings are formed on the ring electrodes to be electrically connected by etching. Next, as shown in FIG. 9(E), a lead electrode layer is formed by vapor deposition or sputtering, and then patterned by etching to form lead wires 51, 52, 53, and 54. Finally, as shown in FIG. 9(F), a uniform resistive layer 7 is formed by vapor deposition or sputtering.

[0035] Fig. 10 is a diagram showing the orientation distribution of liquid crystal molecules in the first state, which is obtained by simulation, and Fig. 11 is a diagram showing the optical retardation distribution occurring in the liquid crystal layer 8 in the first state.

[0036] The conditions for the simulation are explained below. The material of the ring electrodes 1, 2, 3, 4 and the second electrode layer 5 is ITO. The thickness of each ring electrode is 50 nm. The material of the insulating layer 6 is silicon dioxide (SiO2). The thickness of the insulating layer 6 is 0.1 μm. The surface resistivity of the insulating layer 6 is 1×10 15Ω and electrical resistivity is 1×10 10 The resistive layer 7 has resistive layers 71, 72, and 73, each of which has a different electrical resistivity. The resistive layers 71, 72, and 73 are made of a compound containing zinc oxide (ZnO) as the main component. The thickness of the resistive layers 71, 72, and 73 is 0.25 μm. The surface resistivity of the resistive layer 71 is 4×10 8 Ω and electrical resistivity is 1×10 4 The surface resistivity of the resistive layer 72 is 30×10 8 Ω and electrical resistivity is 7.5×10 4 The surface resistivity of the resistive layer 73 is 60×10 8 Ω and the electrical resistivity is 15×10 4 The resistivity is Ω·cm. The material of the liquid crystal layer 8 is nematic liquid crystal E7. The birefringence Δn of the nematic liquid crystal E7 is 0.22 for light with a wavelength of 550 nm. The thickness of the liquid crystal layer 8 is 50 μm. The pretilt angle is 3° on the upper and lower surfaces of the liquid crystal layer 8. The first voltage V1 is 1 V and the frequency is 100 Hz. The second voltage V2 is 2.5 V and the frequency is 100 Hz. The second electrode layer 5 is grounded, and the voltage applied to the second electrode layer 5 is 0 V.

[0037] In FIG. 10, the left end is the center position of the variable power region 101 (102), and the distance from the right end to the left end is 10 mm. That is, the diameter of the variable power region 101 (102) is 20 mm. At the position where the first voltage V1 is applied, the liquid crystal molecules are tilted, and the effective refractive index is high. At the position where the second voltage V2 is applied, the liquid crystal molecules are raised in accordance with the direction of the electric field, and the effective refractive index is low. Furthermore, in the region between the positions where the first and second voltages V1 and V2 are applied, the voltage changes smoothly due to the action of the resistive layer 7, and therefore the orientation of the liquid crystal molecules also changes smoothly. This makes it possible to realize a smoothly shaped refractive index distribution, and therefore to obtain a smooth optical phase difference distribution with a Fresnel lens shape, as shown in FIG. 11.

[0038] Fig. 12 is a diagram showing the orientation distribution of liquid crystal molecules in the second state, which is obtained by simulation, and Fig. 13 is a diagram showing the optical retardation distribution occurring in the liquid crystal layer 8 in the second state.

[0039] The simulation conditions used to obtain the orientation distribution of Figure 12 are basically the same as those used to obtain the orientation distribution of Figure 10, except for the third and fourth voltages V3 and V4 applied to the annular electrodes 3 and 4. The third voltage V3 is 1.8 V and has a frequency of 100 Hz. The fourth voltage V4 is 1.7 V and has a frequency of 100 Hz. The third and fourth voltages V3 and V4 are approximately equal to the average value of the first and second voltages V1 and V2, 2V (= (V1 + V2) / 2).

[0040] In Fig. 12, at the positions where the third and fourth voltages V3 and V4 are applied, the alignment of the liquid crystal molecules changes smoothly without discontinuity. As shown in Fig. 13, a smooth optical phase difference distribution with a Fresnel lens shape, whose pitch is twice that of the optical phase difference distribution in the first state, can be obtained. In this way, the average value of the first and second voltages V1 and V2 is applied to a pair of ring-shaped electrodes arranged at positions where the subscript n of the distance rn from the center of each ring-shaped electrode to the position where the optical phase difference switches is odd. As a result, in the second state, a gentler optical phase difference distribution with an optical phase difference switching pitch twice that of the optical phase difference distribution in the first state can be obtained.

[0041] Fig. 14 is a diagram showing another example of the orientation distribution of liquid crystal molecules in the first state, which is obtained by simulation, and Fig. 15 is a diagram showing another example of the optical retardation distribution generated in the liquid crystal layer 8 in the first state.

[0042] The conditions for the simulation are explained below. The material of the annular electrodes 1, 2, 3, and 4 and the second electrode layer 5 is ITO. The material of the insulating layer 6 is silicon dioxide (SiO2). The thickness of the insulating layer 6 is 0.15 μm. The surface resistivity of the insulating layer 6 is 1×10 15 Ω and the electrical resistivity is 1.5×1010 The resistive layer 7 has resistive layers 71, 72, 73, 74, 75, and 76, each of which has a different electrical resistivity. The resistive layers 71, 72, 73, 74, 75, and 76 are made of a compound containing zinc oxide (ZnO) as the main component. The thickness of the resistive layers 71, 72, 73, 74, 75, and 76 is 0.25 μm. The surface resistivity of the resistive layer 71 is 4×10 8 Ω and electrical resistivity is 1×10 4 The surface resistivity of the resistive layer 72 is 20×10 8 Ω and electrical resistivity is 5×10 4 The surface resistivity of the resistive layer 73 is 30×10 8 Ω and electrical resistivity is 7.5×10 4 The sheet resistivity of the resistive layer 74 is 40×10 8 Ω and electrical resistivity is 10×10 4 The sheet resistivity of the resistive layer 75 is 60×10 8 Ω and the electrical resistivity is 15×10 4 The sheet resistivity of the resistive layer 76 is 80×10 8 Ω and the electrical resistivity is 20×10 4 The resistivity is Ω·cm. The material of the liquid crystal layer 8 is nematic liquid crystal 5CB. The birefringence Δn of the nematic liquid crystal 5CB is 0.18 for light with a wavelength of 550 nm. The thickness of the liquid crystal layer 8 is 50 μm. The pretilt angle is 3° on the upper and lower surfaces of the liquid crystal layer 8. The first voltage V1 is 1 V and the frequency is 100 Hz. The second voltage V2 is 2.5 V and the frequency is 100 Hz. The second electrode layer 5 is grounded, and the voltage applied to the second electrode layer 5 is 0 V.

[0043] In FIG. 14, the left end is the center position of the variable power region 101 (102), and the distance from the right end to the left end is 10 mm. That is, the diameter of the variable power region 101 (102) is 20 mm. In FIG. 14, electrodes 9 are placed at the center of each annular electrode to adjust the orientation of the liquid crystal molecules in the center of the variable power region 101 (102). A first voltage V1 is applied to the electrode 9. At the position where the first voltage V1 is applied, the liquid crystal molecules are tilted, and the effective refractive index is high. At the position where the second voltage V2 is applied, the liquid crystal molecules are raised in accordance with the direction of the electric field, and the effective refractive index is low. Furthermore, in the region between the positions where the first and second voltages V1 and V2 are applied, the voltage changes smoothly due to the action of the resistive layer 7, and therefore the orientation of the liquid crystal molecules also changes smoothly. This allows for a smooth refractive index distribution, and therefore a smooth optical phase difference distribution with a Fresnel lens shape can be obtained, as shown in FIG. 15.

[0044] Fig. 16 is a diagram showing the orientation distribution of liquid crystal molecules in the first state of the comparative example, obtained by simulation, and Fig. 17 is a diagram showing the optical retardation distribution occurring in the liquid crystal layer 8 in the first state of the comparative example.

[0045] The conditions for the simulation are explained below. The material of the annular electrodes 1, 2, 3, and 4 and the second electrode layer 5 is ITO. The material of the insulating layer 6 is silicon dioxide (SiO2). The thickness of the insulating layer 6 is 0.1 μm. The surface resistivity of the insulating layer 6 is 1×10 15 Ω and electrical resistivity is 1×10 10 The resistive layer 7 is made of a compound mainly composed of zinc oxide (ZnO). The resistive layer 7 has a thickness of 0.25 μm. The surface resistivity of the resistive layer 7 is 4×10 8 Ω and electrical resistivity is 1×10 4The resistivity is Ω·cm. The material of the liquid crystal layer 8 is nematic liquid crystal 5CB. The birefringence Δn of the nematic liquid crystal 5CB is 0.18 for light with a wavelength of 550 nm. The thickness of the liquid crystal layer 8 is 50 μm. The pretilt angle is 3° on the upper and lower surfaces of the liquid crystal layer 8. The first voltage V1 is 1 V and the frequency is 100 Hz. The second voltage V2 is 2.5 V and the frequency is 100 Hz. The second electrode layer 5 is grounded, and the voltage applied to the second electrode layer 5 is 0 V.

[0046] In FIG. 17, the left end is the center position of the variable power region 101 (102), and the distance from the right end to the left end is 10 mm. That is, the diameter of the variable power region 101 (102) is 20 mm. In FIG. 17, the electrode 9 is Each electric power The electrode 9 is placed at the center of the electrode. A first voltage V1 is applied to the electrode 9. In FIG. 17, the optical phase difference amount in the peripheral area is smaller than the optical phase difference amount in the central area. difference The distribution also deviates from the Fresnel lens shape. difference quantity and optical phase difference This is not preferable because it is not possible to obtain a desired distribution, which leads to a decrease in optical performance due to insufficient added power or aberrations.

[0047] Desired optical phase from the center to the periphery differenceTo achieve this distribution, the electrical resistivity of the resistive layer 7 needs to be varied from location to location. That is, the resistive layer 7 is configured so that the electrical resistivity at a first position on the resistive layer 7 is different from the electrical resistivity at a second position on the resistive layer 7. The electrical resistivity of the resistive layer 7 is calculated by dividing the sheet resistivity of the resistive layer 7 by the thickness of the resistive layer 7. Therefore, to vary the electrical resistivity of the resistive layer 7 from location to location, the sheet resistivity of the resistive layer 7 may be varied from location to location, or the thickness of the resistive layer 7 may be varied from location to location. Furthermore, between two electrodes to which different voltages are applied, the electrical resistivity needs to be varied depending on the distance between the electrodes. It is preferable to have a low electrical resistivity when the distance between the electrodes is wide and a high electrical resistivity when the distance between the electrodes is narrow. Therefore, it is preferable that the electrical resistivity of the resistive layer 7 is low in the center and high in the peripheral region. In this embodiment, the electrical resistivity of the resistive layer 7 is configured to increase from the center to the peripheral region.

[0048] The electro-active lenses 11, 12 or optical elements having a similar configuration can be used not only in the electronic eyeglasses 10 but also in various optical devices such as binoculars and head-mounted displays. According to this embodiment, an optical element having a plurality of states with different optical powers and an optical device including the same can be easily manufactured.

[0049] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0050] 1. Ring electrode (first electrode) 2. Ring electrode (first electrode) 3. Ring electrode (first electrode) 4. Ring electrode (first electrode) 5 Second electrode 6 insulating layer 7 Resistance layer 8 Liquid Crystal Layer 11 Electroactive Lens (Optical Element) 12 Electroactive Lens (Optical Element)

Claims

1. A semiconductor device comprising: a plurality of electrodes arranged in a first direction; an insulating layer arranged on the plurality of electrodes in a second direction perpendicular to the first direction; a resistive layer arranged on the insulating layer in the second direction; a liquid crystal layer arranged on the resistive layer in the second direction; and an electrode layer arranged on the liquid crystal layer in the second direction; an optical element that, in an electrically activated state, is switchable between a first state and a second state having different focal lengths in response to a change in voltage applied to the plurality of electrodes, the electrical resistivity of the resistive layer increases from the center to the periphery of the optical element in a cross section perpendicular to the second direction, When the electrical resistivity of the insulating layer is R1 and the electrical resistivity of each region of the resistive layer in the first direction is R2, 1×10 -7 <R2 / R1<1×10 -3 An optical element characterized by satisfying the following conditional expression: 【Request 2】 1×10 ２ Ω·cm≦R2≦1×10 ７ Ω・cm 2. The optical element according to claim 1, wherein the following condition is satisfied: 【Request 3】 1×10 ８ Ω·cm≦R2≦1×10 １２ Ω・cm 3. The optical element according to claim 1, wherein the following condition is satisfied:

4. 4. The optical element according to claim 1, wherein the plurality of electrodes includes first to fourth electrodes arranged in the first direction.

5. 5. The optical element according to claim 4, wherein in the first state, a first voltage is applied to the first and third electrodes, and a second voltage is applied to the second and fourth electrodes.

6. 6. The optical element according to claim 4, wherein in the second state, a first voltage is applied to the first electrode, a second voltage is applied to the second electrode, a third voltage is applied to the third electrode, and a fourth voltage is applied to the fourth electrode.

7. 7. The optical element according to claim 5, wherein the magnitudes of the third and fourth voltages are equal to the average values ​​of the first and second voltages.

8. 8. The optical element according to claim 1, wherein a focal length in the first state is shorter than a focal length in the second state.

9. 9. The optical element according to claim 1, wherein the electrical resistivity and thickness of the resistive layer at the first position are different from the electrical resistivity and thickness of the resistive layer at the second position.

10. 9. The optical element according to claim 1, wherein the electrical resistivity and the surface resistivity at the first position of the resistive layer are different from the electrical resistivity and the surface resistivity at the second position of the resistive layer.

11. 11. An optical device comprising: the optical element according to claim 1; and a control unit that changes voltages applied to the plurality of electrodes.

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