JP4697788B2 - Variable focus lens, and focus adjustment device and imaging device using the same - Google Patents

Description

  The present invention relates to a variable focus lens in which a curvature changes due to application of a voltage and a focal length changes, and a focus adjustment apparatus and an imaging apparatus using the variable focus lens.

  In recent years, an imaging apparatus has been mounted on a small electronic device such as a mobile phone, and the size of the imaging apparatus has been reduced. 2. Description of the Related Art Conventionally, in a focus adjustment device that adjusts the focal length between a lens and an image sensor used in these image pickup apparatuses, the distance between the lens and the image sensor is adjusted using an electromagnetic motor. However, when an electromagnetic motor is used, there is a problem that a mechanism for transmitting power is required, the configuration of the focus adjustment device is complicated, and it is difficult to cope with downsizing of the imaging device.

Therefore, by using an actuator made of an electrostrictive material that deforms according to the applied voltage, the lens holder that holds the lens is moved in the optical axis direction of the lens, and the distance between the lens and the image sensor is adjusted. (For example, Patent Document 1).
JP 2003-215429 A

  However, although the structure disclosed in Patent Document 1 is simpler than the case of using an electromagnetic motor or the like, guides and springs are required for controlling the expansion and contraction of the electrostrictive material, and the number of parts is large. The problem that the structure is complicated is not solved.

  Therefore, in order to realize a simple structure by omitting guides, springs, and the like, a variable focus lens capable of changing the focal length of the lens itself, and a focus adjustment device and an imaging device using the variable focus lens are required.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a variable focus lens that has a simple structure and can be reduced in size, and a focus adjustment device and an imaging device using the variable focus lens.

In order to achieve the above object, a variable focus lens according to the first aspect of the present invention includes:
A lens formed from a polyvinyl chloride added with a plasticizer ;
A plate portion on which the lens is installed and having light transmittance;
A first electrode placed in contact with a peripheral edge of the lens and surrounding the peripheral edge of the lens in an annular shape in a radial direction;
A second electrode disposed on the plate portion so as to be in contact with the lens;
When a voltage is applied between the first electrode and the second electrode, the lens is deformed along the first electrode, and the curvature of the lens is changed.

  The surface of the plate portion on the side where the lens is installed may be formed as a concave or convex curved surface.

  The second electrode may be formed so as to have optical transparency and cover the curved surface of the plate portion.

The lens is installed on one surface of the plate part,
A convex or concave curved surface that functions as a lens may be formed on the other surface of the plate portion.

The lens and the second electrode are installed on one surface of the plate part,
Further, a second lens made of polyvinyl chloride added with a plasticizer and placed on the other surface of the plate part, and a third electrode placed in contact with the second lens, A fourth electrode disposed on the other surface of the plate portion so as to be in contact with the second lens, and when a voltage is applied between the third electrode and the fourth electrode The second lens may be deformed along the third electrode, and the curvature of the second lens may change.

In order to achieve the above object, a focus adjustment apparatus according to a second aspect of the present invention includes:
A lens formed from a polyvinyl chloride added with a plasticizer ;
A plate portion on which the lens is installed and having light transmittance;
A lens holder for holding the lens and the plate portion;
A first electrode disposed on the lens holder so as to be in contact with a peripheral portion of the lens and annularly surrounding the peripheral portion of the lens in a radial direction;
A second electrode installed on the lens holder so as to be in contact with the lens,
When a voltage is applied between the first electrode and the second electrode, the lens is deformed along the first electrode, the curvature of the lens is changed, and the focal length is changed. Features.

The lens holder includes a flat plate portion having an opening,
The lens and the plate portion may be held by the flat plate portion.

The first electrode is annularly formed on one surface of the flat plate portion,
The plate portion is formed on the other surface of the flat plate portion;
The second electrode may be formed between the plate portion and the other surface of the flat plate portion.

  The surface of the plate portion on the side where the lens is installed may be formed as a convex or concave curved surface.

  The second electrode may be formed so as to have optical transparency and cover the curved surface of the plate portion.

The lens is installed on one surface of the plate part,
The other surface of the plate portion may be formed as a convex or concave curved surface that functions as a lens.

The lens and the second electrode are installed on one surface of the plate part,
Furthermore, a second lens made of polyvinyl chloride added with a plasticizer and placed on the other surface of the plate part, and a third electrode placed in contact with the second lens, A fourth electrode disposed on the other surface of the plate portion so as to be in contact with the second lens,
The lens holder includes an opening and a second flat plate portion that faces the flat plate portion and holds the second lens and the third electrode.
When a voltage is applied between the third electrode and the fourth electrode, the second lens is deformed along the third electrode, and the curvature of the second lens is changed. Also good.

In order to achieve the above object, an imaging apparatus according to a third aspect of the present invention provides:
A focus adjusting apparatus according to the second aspect;
A substrate on which the focusing device is installed;
And an image pickup device installed on the substrate.

  According to the present invention, by using a variable focus lens that deforms according to an applied voltage and changes its curvature, a focus adjustment device that has a simple structure and can be reduced in size, and an imaging device using the focus adjustment device. Can be provided.

  A variable focus lens according to an embodiment of the present invention, and a focus adjustment device and an imaging device using the same will be described with reference to the drawings.

(First embodiment)
An imaging apparatus 91 according to a first embodiment of the present invention is shown in FIGS. FIG. 2 is a plan view of the imaging device 91. 1 is a cross-sectional view taken along one-dot chain line AA in FIG. FIG. 3 is a cross-sectional view schematically showing a state in which a voltage is applied to the variable focus lens 10 provided in the focus adjustment device 81 constituting the imaging device 91. 4A and 4B are diagrams for explaining the operation of the variable focus lens 10. 2, for convenience of explanation, the flat plate portion 61a and the opening 61b of the lens holder 61, the lens 62, the variable lens 11 constituting the variable focus lens 10, and the positive electrode 13 are particularly illustrated.

  The imaging device 91 according to the first embodiment of the present invention includes a focus adjustment device 81, an imaging element 71, and a substrate 72 as shown in FIG.

  The image sensor 71 converts an optical image of a subject into an electrical signal, and is composed of a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor) image sensor, etc., for example, as shown in FIG. 72 is installed.

  As shown in FIG. 1, the focus adjustment device 81 includes a variable focus lens 10, a lens holder 61, and a lens 62. As shown in FIGS. 1 to 4, the variable focus lens 10 includes a variable lens 11, a plate part 12, a positive electrode 13, and a negative electrode 14.

  The variable lens 11 is formed of a polymer having a property of being deformed in response to application of a voltage. In the present embodiment, the variable lens 11 is formed of polyvinyl chloride added with a plasticizer. The variable lens 11 is formed in a circular shape in plan view as shown in FIG. 2, covers the negative electrode 14 formed on the concave portion 12 a of the plate portion 12 as shown in FIG. 1, and is further covered by a flat plate portion 61 c of the lens holder 61. It is installed so as to cover part of the positive electrode 13 formed on the surface facing the flat plate portion 61a (surface facing the lens 62). Further, the variable lens 11 is formed such that the voltage applied between the positive electrode 13 and the negative electrode 14 is zero, that is, the planar shape is substantially circular as shown in FIG. 2 in the initial state. When the voltage applied between the positive electrode 13 and the negative electrode 14 is increased from zero, the polymer constituting the variable lens 11 is attracted to the positive electrode 13, and therefore, along the positive electrode 13 as shown in FIG. 3. To deform radially outward. As a result, the curvature of the variable lens 11 changes, and the focal length of the variable focus lens 10 changes. It should be noted that the curvature of the surface of the variable lens 11 facing the image sensor 71 (the surface facing the plate portion 12) is kept constant and does not change with the application of voltage.

  Further, when the refractive index of the variable lens 11 is n1, the refractive index of the plate portion 12 is n2, and the refractive index of the atmosphere is n3, when the difference between n2 and n1 is less than the difference between n3 and n2, Refraction at the boundary surface between the variable lens 11 and the plate portion 12 cannot be obtained effectively. For this reason, it is preferable that the material of the variable lens 11 and the plate part 12 has a property that the difference between n2 and n1 exceeds the difference between n3 and n2.

  Further, the polyvinyl chloride and the plasticizer constituting the variable lens 11 are determined from the amount of displacement, strength, etc. required for each layer as described later, and for example, a ratio of 1: 9 (polyvinyl chloride: plasticizer). Mixed in. In addition, the hardness of the variable lens 11 is determined by the degree of polymerization of polyvinyl chloride used, the amount of plasticizer mixed in, and the nature of the plasticizer used. Determine.

  Specifically, for example, regarding polyvinyl chloride, in the present embodiment, it is preferable to use polyvinyl chloride having a polymerization degree of 1100. For example, polyvinyl chloride having a polymerization degree of 3700 can contain a lot of plasticizers and has a high strength and is preferable. However, since the transparency is lower than that of a polymerization degree of 1100, a variable focus lens as in this embodiment. It is not suitable for use as 10.

  Next, the plasticizer is preferably a phthalate ester type, such as dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP (DOP)), di-normal octyl phthalate (DnOP), diisononyl phthalate ( DINP), diisodecyl phthalate (DIDP), and diundecyl phthalate (DUP) are more preferable. In general, as the amount of these plasticizers added to polyvinyl chloride increases, the gel of the polyvinyl chloride becomes flexible and the amount of displacement when a voltage is applied tends to increase. Each plasticizer shows a tendency that the longer the straight chain of the ester group, the smaller the displacement amount when a voltage is applied to the polyvinyl chloride. Further, if the ester group has a branch, the amount of displacement when a voltage is applied tends to be small.

  The variable lens 11 is formed as described below. First, for example, dibutyl phthalate is added to polyvinyl chloride as a plasticizer and dissolved in tetrahydrofuran (THF). Subsequently, this solution is poured into a mold that is previously molded into the shape of the variable lens 11 and left for several days. By allowing it to stand, the tetrahydrofuran evaporates and the variable lens 11 is formed.

  In order to protect from the external environment, the surface of the variable lens 11 may be covered with a thin elastic film such as polyurethane or polyparaxylylene resin (parylene).

  The plate portion 12 is made of a light-transmitting material, such as plastic or glass, and has a circular shape in plan view. The plate portion 12 is installed on the lower surface of the flat plate portion 61 c of the lens holder 61 (the surface facing the imaging element 71) via the negative electrode 14. As shown in FIG. 1, the plate portion 12 includes a concave portion 12 a formed in a concave curved surface on a surface facing the lens 62. In addition, unlike the recessed part 12a, the surface facing the image pick-up element 71 of the board part 12 is formed in planar shape. The concave portion 12a is formed in the plate portion 12 and the variable lens 11 is formed so as to fill the concave portion 12a via the negative electrode 14, so that the surface of the variable lens 11 that faces the image pickup device 71 has a convex shape. Is preserved. Therefore, even when a voltage is applied to the variable lens 11, the curvature of the surface of the variable lens 11 that faces the imaging element 71 can be kept constant.

  The positive electrode 13 is composed of, for example, an inorganic conductive material such as carbon black, gold, silver, aluminum, phosphor bronze, or an organic conductive material such as an organic conductive polymer. As shown in FIGS. An annular shape is formed on the flat plate portion 61 c of the holder 61. As described above, when a voltage is applied between the positive electrode 13 and the negative electrode 14, the variable lens 11 is deformed along the positive electrode 13. In the present embodiment, in order to deform the variable lens 11 to the outside in the radial direction, the positive electrode 13 is formed wider on the outside in the radial direction than the variable lens 11 as shown in FIG.

The negative electrode 14 is made of a conductive material having optical transparency, for example, ITO. The negative electrode 14 is formed in a circular shape in plan view so as to cover the entire surface of the plate portion 12 between the lower surface of the flat plate portion 61 c of the lens holder 61 and the plate portion 12.
The positive electrode 13 and the negative electrode 14 are connected to a power source (not shown) and a control unit (not shown), and the positive electrode 13 and the negative electrode 14 are input according to an input from the control unit (not shown). A voltage is applied between the two.

Next, the case where a voltage is applied to the variable focus lens 10 will be described with reference to FIG.
When the voltage applied to the positive electrode 13 and the negative electrode 14 of the variable focus lens 10 in the initial state shown in FIG. Therefore, the variable lens 11 is deformed radially outward so as to cover the positive electrode 13 as shown in FIG. The thickness of the variable lens 11 changes from Ta to Tb, and the radius of curvature of the variable lens 11 increases, in other words, the curvature decreases, and the focal length of the variable lens 11 increases.

  Further, when the voltage applied to the positive electrode 13 and the negative electrode 14 is returned to zero, the polyvinyl chloride constituting the variable lens 11 is not attracted to the positive electrode 13, and the variable lens 11 is shown in FIG. Return to the initial state. In this way, the focal length of the variable focus lens 10 is changed.

  The lens holder 61 is formed in a cylindrical shape as shown in FIGS. 1 and 2, and holds the variable focus lens 10 and the lens 62 inside thereof. The lens holder 61 includes a flat plate portion 61a and a flat plate portion 61c. The flat plate portion 61 a has an opening 61 b corresponding to the diameter of the lens 62. The flat plate portion 61 c includes an opening 61 d corresponding to the variable focus lens 10. The opening 61b and the opening 61d are formed to have substantially the same diameter. The positive electrode 13 is formed on the surface of the flat plate portion 61c that faces the flat plate portion 61a. Further, the negative electrode 14 is formed on the surface of the flat plate portion 61c facing the image sensor 71. Thus, since the positive electrode 13 and the negative electrode 14 are formed on the flat plate portion 61c of the lens holder 61, at least the flat plate portion 61c of the lens holder 61 is formed of an insulating material in order to electrically insulate both. Are preferred, specifically formed from PET (polyethylene terephthalate).

  The lens 62 includes a plastic lens, a glass lens, and the like, and collects an optical image of the subject together with the variable focus lens 10. As described above, the curvature of the varifocal lens 10 changes according to the voltage applied between the positive electrode 13 and the negative electrode 14, but the curvature of the lens 62 is constant.

  In the variable focus lens 10 of the present embodiment, the variable lens 11 itself is deformed according to the applied voltage, and the focal length changes as the curvature changes. Therefore, unlike the conventional configuration in which the lens holder that holds the lens is moved in the optical axis direction by an actuator or the like to adjust the focal length, the actuator, power transmission means, guide, and the like can be omitted. As a result, the focus adjustment device 81 can be reduced in size, and further, the imaging device 91 can be easily reduced in size.

  Furthermore, in the variable focus lens 10 according to the present embodiment, by forming the concave portion 12a in the plate portion 12, one surface of the variable lens 11 can be easily formed into a convex curved surface. Therefore, for example, it is possible to suppress the distortion of the image due to the influence of the aberration that has occurred when both surfaces of the plate portion 12 are formed in a planar shape, and to obtain a good image.

  In addition, since the varifocal lens 10 of the present embodiment has one surface of the variable lens 11 along the recess 12a, the curvature can be easily kept constant. Therefore, it is possible to easily keep the curvature of the other surface constant while changing the curvature of one surface of the lens 11.

(Second Embodiment)
An imaging device 92 according to a second embodiment of the present invention is shown in FIGS. 6 is a plan view of the imaging device 92 according to the present embodiment, and FIG. 5 is a cross-sectional view taken along the line BB of FIG. In FIG. 6, for convenience of explanation, the flat plate portion 61 a of the lens holder 61, the opening 61 b, the variable lens 21 constituting the variable focus lens 20, and the positive electrode 23 are illustrated, and the others are omitted. Yes. The variable focus lens 20 according to the second embodiment is different from the variable focus lens 10 according to the first embodiment in that the shape of the plate portion is different. Parts common to the first embodiment are given the same reference numerals as those of the first embodiment, and detailed description thereof is omitted.

  The imaging device 92 according to the present embodiment includes a focus adjustment device 82, an imaging element 71, and a substrate 72. The focus adjustment device 82 includes a variable focus lens 20, a lens holder 61, and a lens 62. The variable focus lens 20 includes a variable lens 21, a plate portion 22, a positive electrode 23, and a negative electrode 24, as in the first embodiment. The variable focus lens 20 is held in a lens holder 61.

  As in the first embodiment, the variable lens 21 is made of polyvinyl chloride mixed with a plasticizer, and is formed in a circular shape in plan view as shown in FIG. The variable lens 21 is installed so as to cover the negative electrode 24 formed on the plate portion 22 and further cover a part of the positive electrode 23 formed on the flat plate portion 61 c of the lens holder 61. When a voltage is applied between the positive electrode 23 and the negative electrode 24, the variable lens 21 is deformed radially outward along the positive electrode 23, and the curvature of the variable lens 21 changes.

  The plate portion 22 is made of a light transmissive material, such as plastic or glass, and is installed on the lower surface of the flat plate portion 61 c of the lens holder 61 (the surface facing the image sensor 71) via the negative electrode 24. The surface of the plate portion 22 on which the negative electrode 24 is formed is formed in a flat shape, and the surface of the plate portion 22 that faces the image sensor 71 is formed in a convex curved surface, which functions as a convex lens.

  The positive electrode 23 is made of, for example, an inorganic conductive material such as carbon black, gold, silver, aluminum, phosphor bronze, or an organic conductive material such as an organic conductive polymer, and is formed on the flat plate portion 61c as shown in FIG. It is formed. A part of the positive electrode 23 is covered with the variable lens 21.

The negative electrode 24 is made of a conductive material having optical transparency, for example, ITO. The negative electrode 24 is formed so as to cover the plate portion 22 as shown in FIG.
The positive electrode 23 and the negative electrode 24 are connected to a power source (not shown) and a control unit (not shown), and the positive electrode 23 and the negative electrode 24 are input in accordance with an input from the control unit (not shown). A voltage is applied between the two.

  In the variable focus lens 20 according to the present embodiment, since the variable lens 21 itself is deformed and the curvature is changed by applying a voltage, the focus adjustment device 82 and the imaging device 92 are reduced in size as in the first embodiment. Can be realized. In the varifocal lens 20 of the present embodiment, the surface of the plate portion 22 facing the image sensor 71 is formed as a convex curved surface so as to function as a convex lens. In this case, it is possible to suppress image distortion due to the influence of aberration that occurs.

  In the first embodiment described above, the relationship between the refractive index n2 of the plate portion 12, the refractive index n1 of the variable lens 11, and the refractive index n3 of the atmosphere is such that the difference between n2 and n1 is n2 and n3. It was necessary to adjust the material of the lens 11 and the plate part 12 so as to be larger than the difference. However, in the present embodiment, since one surface of the plate portion 22 functions as a lens, for example, the first embodiment as in the case where the refractive index of the variable lens 21 and the refractive index of the plate portion 22 are substantially the same. Therefore, it is possible to use a material that is difficult to use.

(Third embodiment)
An imaging device 93 according to a third embodiment of the present invention is shown in FIGS. 8 is a plan view showing the imaging device 93, and FIG. 7 is a cross-sectional view taken along the line CC of FIG. In FIG. 8, for convenience of explanation, the flat plate portion 61a, the opening 61b, the variable lens 31a, and the positive electrode 33a of the lens holder 61 are illustrated, and the others are omitted. The variable focus lens 30 according to the present embodiment is different from the variable focus lenses 10 and 20 of the above-described embodiment in that the variable lenses are formed on both surfaces of the plate portion. Parts common to the above-described embodiment are given the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 7 and 8, the imaging device 93 includes a focus adjustment device 83, an imaging element 71, and a substrate 72. The focus adjustment device 83 includes a variable focus lens 30, a lens holder 61, and a lens 62.

  The variable focus lens 30 includes variable lenses 31a and 31b, a plate portion 32, positive electrodes 33a and 33b, and negative electrodes 34a and 34b. The variable focus lens 30 is installed in the lens holder 21 as shown in FIG.

  Each of the variable lenses 31a and 31b is made of polyvinyl chloride mixed with a plasticizer similarly to the first embodiment, and is formed in a circular shape in plan view. The variable lens 31a is formed on the negative electrode 34a formed on the surface (light incident surface) facing the lens 62 of the plate portion 32. On the other hand, the variable lens 31b is formed on the negative electrode 34b formed on the surface of the plate portion 32 facing the imaging element 71. The variable lens 31a is formed so as to be in contact with the positive electrode 33a, and the variable lens 31b is formed so as to be in contact with the positive electrode 33b.

  In addition, the variable lens 31a and the variable lens 31b are electrically insulated by the plate part 32, and a voltage is applied separately, and a curvature changes each independently. For example, when a voltage is applied between the positive electrode 33a and the negative electrode 34a, the variable lens 31a is deformed outward in the radial direction so as to be pulled by the positive electrode 33a. In this way, the curvature of the variable lens 31a changes. On the other hand, when a voltage is applied between the positive electrode 33b and the negative electrode 34b, the variable lens 31b is deformed radially outward so as to be pulled by the positive electrode 33b. In this way, the curvature of the variable lens 31b changes.

  The variable lens 31a and the variable lens 31b may be formed with substantially the same hardness, or may be formed with different hardnesses by changing the polymerization degree of polyvinyl chloride and the plasticizer used. These can be appropriately changed according to the properties required for the variable focus lens 30.

  The plate portion 32 is formed from a light transmissive material, such as plastic or glass. The plate portion 32 is formed in a circular shape in plan view, and the surface facing the lens 62 and the surface facing the image sensor 71 are each formed as a convex curved surface. The plate portion 32 is provided between the flat plate portion 61c and the flat plate portion 61e, and has negative electrodes 34a and 34b formed on the surface facing the lens 62 and the surface facing the image sensor 71, respectively, and thus has insulation. Made of material.

  The positive electrodes 33a and 33b are made of an inorganic conductive material such as carbon black, gold, silver, aluminum, and phosphor bronze, or an organic conductive material such as an organic conductive polymer, for example, a phosphor bronze plate, and the flat plate portions 61c and 61e. Annulus is formed on the top.

The negative electrodes 34a and 34b are made of a conductive material having optical transparency, for example, ITO. The negative electrodes 34a and 34b are formed in a circular shape in plan view so as to cover the surface of the plate portion 32 facing the lens 62 and the surface facing the image sensor 71, respectively.
The positive electrodes 33a and 33b and the negative electrodes 34a and 34b are respectively connected to a power source (not shown) and a control unit (not shown), and voltages are individually applied thereto.

  Since the variable lenses 31a and 31b themselves are deformed and the curvature is changed by applying a voltage to the variable focus lens 30 according to the present embodiment, the focus is the same as in the first and second embodiments. The adjustment device 83 and the imaging device 93 can be reduced in size. In the varifocal lens 30 of the present embodiment, the variable lenses 31a and 31b are formed on both surfaces of the plate portion 32. For example, the variable lens is provided on one surface of the plate portion, and both surfaces of the plate portion are formed flat. In this case, distortion of the image due to the influence of the aberration that occurs can be suppressed, and a good image can be obtained.

  Furthermore, in the variable lens 30 of the present embodiment, the variable lenses 31a and 31b, the positive electrodes 33a and 33b, and the negative electrodes 34a and 34b are formed on the upper and lower surfaces of the insulating plate portion 32, and the variable lens 31a. , 31b can be independently applied with a voltage, so that the curvature of the variable lens 31a or 31b or both can be freely changed. Therefore, it is possible to widen the change in the curvature of the varifocal lens 30, in other words, the change in the focal length.

The present invention is not limited to the above-described embodiments, and various modifications and applications are possible.
For example, in the first embodiment described above, the case where the plate portion 12 includes the concave portion 12a has been described as an example, but the present invention is not limited thereto. For example, as shown in FIG. 9, it is also possible to form the convex part 12b which is a convex curved surface in the board part 12. As shown in FIG. In this case, the surface of the variable lens 11 facing the image sensor 71 is concave, and this surface can function as a concave lens.

  Similarly, in the above-described second embodiment, the case where the surface of the plate portion 22 facing the imaging element 71 is formed in a convex shape has been described as an example. However, the present invention is not limited thereto, and for example, as illustrated in FIG. It is also possible to form a concave curved surface.

  In each of the above-described embodiments, the case where the variable lens 11 is a convex lens has been described as an example. However, the present invention is not limited to this and may be a concave lens. In this case, for example, as shown in FIG. 11, the variable focus lens 40 is installed in a focus adjustment device 84 that constitutes the imaging device 94.

  The variable focus lens 40 includes a variable lens 41, a plate portion 42, a positive electrode 43, and a negative electrode 44. The variable lens 41 is formed in a concave spherical surface as shown in FIG. The variable lens 41 is installed so as to be in contact with the positive electrode 43 and the negative electrode 44. The plate portion 42 includes a concave portion 42a formed in a concave curved surface. Unlike the embodiment described above, the positive electrode 43 is formed on the inner peripheral surface of the opening 61 d formed in the flat plate portion 61 c of the lens holder 61. The negative electrode 44 is formed so as to cover the concave portion 42 a of the plate portion 42.

  When a voltage is applied to the variable focus lens 40, as shown in FIG. 12, the variable lens 41 is deformed upward along the positive electrode 43, and the curvature of the variable lens 41 changes. In this case, the radius of curvature of the variable lens 41 decreases, in other words, the curvature of the variable lens 41 increases and the focal length decreases.

  In each of the above-described embodiments, the case where the negative electrode is formed so as to cover the entire one surface of the plate portion has been described as an example. However, a displacement amount required for the variable lens can be obtained. In this case, for example, a negative electrode 15 shown in FIG. 13 may be formed on the lower surface of the flat plate portion 61c so as to cover a part of the plate portion 12.

  In each of the above-described embodiments, the case where the voltage applied to the variable focus lens changes in one step has been described as an example. However, the present invention is not limited to this, and the voltage applied to the variable focus lens can be set in multiple steps. It is also possible to change the curvature of the variable focus lens in multiple stages.

  In each of the above-described embodiments, the case where the flat plate portion 61c of the lens holder 61 is formed integrally with the lens holder 61 has been described as an example. However, the present invention is not limited thereto, and the variable lens 11 on the flat plate portion 61c, It is also possible to adopt a configuration in which the positive electrode 13 and the like are formed and then installed in the lens holder 61.

  In each of the above-described embodiments, the case where polyvinyl chloride is used has been described as an example. However, if it has a property of deforming according to the voltage applied between the positive electrode and the negative electrode, It is also possible to use materials other than vinyl.

  In each of the embodiments described above, the configuration in which the optical image of the subject is collected by two lenses has been described as an example. However, the present invention is not limited to this, and a configuration using, for example, three lenses can be employed. It is. Further, the position of the variable focus lens is also arbitrary, and a configuration in which a lens is installed between the variable focus lens and the image sensor can be employed.

It is sectional drawing of the imaging device which concerns on the 1st Embodiment of this invention. 1 is a plan view of an imaging apparatus according to a first embodiment of the present invention. It is sectional drawing of an imaging device when a voltage is applied to the variable focus lens installed in the imaging device which concerns on 1st Embodiment of this invention. It is a figure which shows typically operation | movement of the variable focus lens which concerns on the 1st Embodiment of this invention. It is sectional drawing of the imaging device which concerns on the 2nd Embodiment of this invention. It is a top view of the imaging device concerning a 2nd embodiment of the present invention. It is sectional drawing of the imaging device which concerns on the 3rd Embodiment of this invention. It is a top view of the imaging device concerning a 3rd embodiment of the present invention. It is sectional drawing which shows the modification of embodiment of this invention. It is sectional drawing which shows the modification of embodiment of this invention. It is sectional drawing which shows the modification of embodiment of this invention. It is sectional drawing which shows the state in which the voltage was applied to the variable focus lens shown in FIG. It is sectional drawing which shows the modification of embodiment of this invention.

Explanation of symbols

10, 20, 30 Variable focus lens 11, 21, 31a, 31b Variable lens 12, 22, 32 Plate portion 13, 23, 33a, 33b Positive electrode 14, 24, 34a, 34b Negative electrode 61 Lens holder 62 Lens 71 Imaging element 72 Substrate 81, 82, 83 Focus adjustment device 91, 92, 93 Imaging device

Claims (13)

A lens formed from a polyvinyl chloride added with a plasticizer ;
A plate portion on which the lens is installed and having light transmittance;
A first electrode placed in contact with a peripheral edge of the lens and surrounding the peripheral edge of the lens in an annular shape in a radial direction;
A second electrode disposed on the plate portion so as to be in contact with the lens;
The variable focus, wherein when a voltage is applied between the first electrode and the second electrode, the lens is deformed along the first electrode, and the curvature of the lens changes. lens.   The variable focus lens according to claim 1, wherein a surface of the plate portion on a side where the lens is installed is formed as a concave or convex curved surface.   The variable focus lens according to claim 2, wherein the second electrode has light transmissivity and is installed so as to cover the curved surface of the plate portion. The lens is installed on one surface of the plate part,
The variable focus lens according to claim 1, wherein a convex or concave curved surface that functions as a lens is formed on the other surface of the plate portion. The lens and the second electrode are installed on one surface of the plate part,
Further, a second lens made of polyvinyl chloride added with a plasticizer and placed on the other surface of the plate part, and a third electrode placed in contact with the second lens, A fourth electrode disposed on the other surface of the plate portion so as to be in contact with the second lens, and when a voltage is applied between the third electrode and the fourth electrode The variable focus lens according to claim 1, wherein the second lens is deformed along the third electrode, and the curvature of the second lens is changed. A lens formed from a polyvinyl chloride added with a plasticizer ;
A plate portion on which the lens is installed and having light transmittance;
A lens holder for holding the lens and the plate portion;
A first electrode disposed on the lens holder so as to be in contact with a peripheral portion of the lens and annularly surrounding the peripheral portion of the lens in a radial direction;
A second electrode installed on the lens holder so as to be in contact with the lens,
When a voltage is applied between the first electrode and the second electrode, the lens is deformed along the first electrode, the curvature of the lens is changed, and the focal length is changed. Focus adjustment device characterized. The lens holder includes a flat plate portion having an opening,
The focus adjusting apparatus according to claim 6, wherein the lens and the plate portion are held by the flat plate portion. The first electrode is annularly formed on one surface of the flat plate portion,
The plate portion is formed on the other surface of the flat plate portion;
The focus adjusting apparatus according to claim 7, wherein the second electrode is formed between the plate portion and the other surface of the flat plate portion.   The focus adjustment apparatus according to claim 8, wherein a surface of the plate portion on which the lens is installed is formed as a convex or concave curved surface.   The focus adjusting apparatus according to claim 9, wherein the second electrode has light transmissivity and is formed so as to cover the curved surface of the plate portion. The lens is installed on one surface of the plate part,
The focus adjustment device according to claim 6, wherein the other surface of the plate portion is formed into a convex or concave curved surface that functions as a lens. The lens and the second electrode are installed on one surface of the plate part,
Furthermore, a second lens made of polyvinyl chloride added with a plasticizer and placed on the other surface of the plate part, and a third electrode placed in contact with the second lens, A fourth electrode disposed on the other surface of the plate portion so as to be in contact with the second lens,
The lens holder includes an opening and a second flat plate portion that faces the flat plate portion and holds the second lens and the third electrode.
When a voltage is applied between the third electrode and the fourth electrode, the second lens is deformed along the third electrode, and the curvature of the second lens is changed. The focus adjustment apparatus according to claim 7. The focus adjustment device according to any one of claims 6 to 12,
A substrate on which the focusing device is installed;
An image pickup device comprising: an image pickup device installed on the substrate.

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