JP2007208587A - Imaging structure of camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thin imaging structure of a camera which can be manufactured at low cost. <P>SOLUTION: In the structure, a shutter 20 composed of distributed liquid crystal elements is arranged between a lens-barrel 16 housing a plurality of lenses 12, 14 and 15 and a diaphragm 13 and having the capability of an auto focus function, and an image-forming member 19 comprising a solid-state image sensor such as a CCD, and the distributed liquid crystal elements are provided with an IR-cut filter. The distributed liquid crystal elements use a polymer-dispersed liquid crystal element using liquid crystal in a PNLC mode, and an IR-cut evaporated film is formed on a transparent substrate made of glass at a position where the liquid crystal element is configured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging structure of a camera, and more particularly to a liquid crystal shutter using a liquid crystal element.

  In recent years, digital cameras (electronic cameras) that do not use film have become very popular. An optical sensor such as a CCD or CMOS is used instead of the film, and the photographed image is recorded as digital image data in an internal memory or a memory card. This digital camera is also used in a camera-equipped mobile phone.

  The camera imaging structure of the camera-equipped mobile phone has a structure generally shown in FIG. FIG. 9 is a layout diagram of main components schematically showing an example of the conventional structure of the camera of the camera-equipped mobile phone. FIG. 9A is a perspective view showing the layout of the main components. 9 (b) shows a cross-sectional view of the main part of the frame unit in (a). In FIG. 9, an arrow indicated by P indicates the incident direction of the imaging light P of the image. The shutter 1 is first directed toward the imaging light P, then the frame unit 6 accommodates a plurality of lenses and the like, IR ( (Infrared) cut filter 8 and imaging member 9 are arranged side by side in sequence.

  In addition, the first lens 2, the diaphragm 3, the second lens 4, and the third lens 5 are sequentially arranged in the frame unit 6 toward the photographing light P. The frame unit 6 has a frame 6a and a lid 6d on the outer side, and further has a fixed lens barrel 6b and a movable lens barrel 6c constituting the lens barrel inside the frame 6a. The first lens 2, the diaphragm 3, and the second lens 4 are fixed to the fixed barrel 6b and are fixed to the frame 6a. The movable lens barrel 6c fixes the third lens 5 and slides up and down with the inner diameter surface of the stationary lens barrel 6b. The third lens 5 is a focus lens, and moves up and down as indicated by arrows toward the incident direction of the photographing light P via the movable lens barrel 6c, and functions as an autofocus for adjusting the focal length. Yes. The movable barrel 6c is moved up and down along the inner diameter surface of the fixed barrel 6b by an actuator 7 using a flat stepping motor or the like disposed on the side surface of the frame 6a. The lid 6d has an opening 6e through which the photographing light P is incident and closes the frame 6a.

  The frame 6a is made of a plastic molded body, and has a substantially cylindrical shape with a square outer shape and a circular inner shape. Further, the fixed barrel 6b and the movable barrel 6c disposed therein are made of a plastic molded body and have a substantially cylindrical shape. Then, the first lens 2, the diaphragm 3, the second lens 4, the third lens 5 and the like are housed therein, and the adjustment of the light amount of the photographing light P, the adjustment of the focal length, and the like are performed.

  The shutter 1 uses a mechanical shutter (hereinafter referred to as a mechanical shutter), and includes two blades 1a and 1b and a motor 1c as main components. The two blades 1a and 1b are of a double opening type and are opened and closed by a motor 1c. When opened, the photographing light P passes and enters the opening 6 e of the frame unit 6. When closed, the photographing light P is blocked. Normally, it is in the open state, and when the shutter switch is pressed, the close-open-close operation is repeated to take a picture.

  The IR cut filter 8 is provided to prevent an image on the imaging member 9 made of a CCD or the like from becoming a pink (purple) color in an environment where there is a lot of infrared rays such as outdoors. The IR cut filter 8 transmits visible light and reflects infrared rays.

  The imaging member 9 uses a solid-state image sensor such as a CCD or CMOS in a digital camera.

  The market needs for mobile phones are particularly strongly demanded to be low-priced, thinner and smaller. The same applies to camera-equipped mobile phones. However, since a mechanical shutter is used for the shutter 1, there is a limit to downsizing because a space for preventing blades is required, and the thickness is also thick because a large number of machined parts are assembled. Therefore, there is a limit to thinning. Of course, the manufacturing cost is high, and a failure is easily caused by an impact caused by dropping.

  In addition, the frame unit 6 for housing the lens barrel and the plurality of lenses is squared because an actuator 7 using a flat type stepping motor is mounted on the side surface, and has a limit in miniaturization. Since the lens needs to be moved up and down, the thickness of the movement increases and there is a limit to the reduction in thickness. Further, since an actuator or the like is used, the manufacturing cost is high, and a failure is likely to occur due to an impact caused by dropping or the like.

    The present invention has been made in view of the above problems, and an object thereof is to find an imaging structure having a configuration that can be reduced in thickness and size, can be manufactured at a low cost, and does not easily fail due to an impact caused by dropping or the like. It is to make.

  As a means for achieving the above object, the imaging structure of the camera of the present invention is characterized in that at least the imaging structure of the camera having a plurality of photographing lenses, a shutter, an aperture, and an imaging member has the dispersion liquid crystal. The dispersion type liquid crystal element is arranged in front of the imaging member, and an IR (infrared) cut filter is provided on the dispersion type liquid crystal element.

  The imaging structure of the camera according to the present invention is characterized in that, at least in the imaging structure of a camera having a plurality of photographing lenses, a shutter, a diaphragm, and an imaging member, a liquid crystal lens having a focusing function is arranged integrally with the diaphragm. And the shutter is composed of a dispersive liquid crystal element, the dispersive liquid crystal element is disposed in front of the imaging member, and an IR (infrared) cut filter is provided on the dispersive liquid crystal element. To do.

  Further, the imaging structure of the camera of the present invention is characterized in that the dispersive liquid crystal element is a liquid crystal element using PNLC mode liquid crystal.

  In addition, the imaging structure of the camera of the present invention is characterized in that the liquid crystal lens has a circular outer shape.

  In addition, the imaging structure of the camera according to the present invention is characterized in that the dispersion type liquid crystal element is housed in a lens barrel together with the photographing lens and the diaphragm.

  In addition, the imaging structure of the camera of the present invention is characterized in that the dispersion type liquid crystal element has a circular outer shape.

  As an effect of the invention, the shutter is composed of a dispersion type liquid crystal element. This creates a light transmission and non-transmission state according to the voltage application state, and thus functions as a shutter. Therefore, unlike the prior art, there is no need for a space for avoiding the blades. Further, when it is composed of a dispersion type liquid crystal element, it can be formed thin. In addition, since a required air space for imaging is provided in front of the imaging member, a thin dispersed liquid crystal element can be disposed in this air space, and can be disposed without hindering thinning. Therefore, the thickness of the shutter can be reduced by simply changing the position where the shutter is constituted by the dispersive liquid crystal element and changing the position. In addition, when it is arranged in front of the imaging member, a light transmission area larger than the size of the imaging member is required. However, it is easy to change the size in the dispersive liquid crystal element, and the cost is almost the same. it can. The effect of thinning appears greatly.

  Further, by providing an IR cut filter in the dispersion type liquid crystal element, the infrared ray is cut there, so that the imaging member is protected from the infrared ray. Further, when the dispersion type liquid crystal element and the IR cut filter are integrated, it is possible to reduce the time and effort of assembly.

  Next, a liquid crystal lens having a focus function is disposed integrally with the diaphragm. Thereby, it is possible to eliminate the movement of the focus lens which has been performed in the prior art. And the actuator etc. which were used by the prior art can be eliminated, and the effect of cost reduction is acquired. Further, by eliminating the actuator, the square frame that accommodates the lens barrel used in the prior art can be formed into a round cylindrical shape, and the frame and the lens barrel can be integrated into a single component. . Thereby, the square cylindrical shape used in the prior art can be reduced in size by making it circular, and the cost can be reduced by being configured with one component. Further, when the liquid crystal lens is used integrally with the stop, the lens functional area of the liquid crystal lens can be made a minimum area, and an effect of widening the adjustment range of the focal length can be obtained. Further, it is possible to reduce the thickness of the lens barrel by eliminating the movement of the focus lens, and when combined with the effect of reducing the thickness by configuring the shutter with the above-described dispersion type liquid crystal element, a great effect of reducing the thickness can be obtained. Furthermore, by forming the outer shape of the liquid crystal lens in a circular shape, it becomes possible to reduce the cost of the lens barrel component, and obtain a cost reduction effect.

  Note that a liquid crystal element using a PNLC mode liquid crystal is used as the dispersion type liquid crystal element. Since it can be driven at a low voltage, the power consumption is small, and it can be suitably used for mobile phones.

  Further, when the dispersion type liquid crystal element is housed in a lens barrel together with a lens, a diaphragm and the like, a series of components are unitized to facilitate assembly and handling is also facilitated. Further, when the outer shape of the dispersive liquid crystal element is circular, the shape of the lens barrel is also easy to manufacture, which brings about the effect of reducing the manufacturing cost.

  Hereinafter, the best mode for carrying out the present invention will be described. First, the imaging structure of the camera according to the first embodiment of the present invention will be described with reference to FIGS. Note that the imaging structure of the camera according to the first embodiment is the imaging structure of a camera for a mobile phone. FIG. 1 shows a layout of the main components of the imaging structure of the camera according to the first embodiment of the present invention and a cross-sectional view of the main part of the frame unit. FIG. 1 (a) shows the layout of the main components. FIG. 1B is a cross-sectional view of the main part of the frame unit in FIG. FIG. 2 is a cross-sectional view of the main part of the shutter in FIG.

  As shown in FIG. 1A, the imaging structure of the camera according to the first embodiment of the present invention includes a frame unit 16 that houses a photographic lens, a lens barrel, and the like in the incident direction of the photographic light P, and a distributed type. A shutter 20 made of a liquid crystal element and an imaging member 19 made of an image pickup element are arranged in order from the top. As shown in FIG. 1B, the frame unit 16 houses a plurality of photographing lenses, diaphragms, etc., and sets the amount of photographing light P to be taken into the camera with the photographing lenses and the diaphragm and adjusts the focal length. Is going. The shutter 20 is composed of a PNLC mode dispersion type liquid crystal element provided with an IR (infrared) cut filter, and utilizes the change between the transparent state and the cloudiness state due to voltage application ON-OFF of the dispersion type liquid crystal element. The transmission and non-transmission of the photographic light. That is, it functions as a shutter. A solid-state imaging device such as a CCD or CMOS is used as the imaging device that is the imaging member 19.

  Next, the frame unit 16 has the same component configuration as that of the above-described prior art, and uses the same specification. In other words, the frame 16a is a substantially cylindrical frame having a square outer shape and a round inner shape, and a lens barrel containing a plurality of photographing lenses and diaphragms is disposed. And the upper part consists of what was block | closed with the lid | cover 16d which provided the opening part 16e for taking in the imaging light P. FIG. The lens barrel is composed of a fixed lens barrel 16b and a movable lens barrel 16c. The fixed lens barrel 16b accommodates and fixes the first lens 12, the diaphragm 13, the second lens 14, and the like, and is fixed to the inner diameter portion of the frame 16a. The lens barrel 16c accommodates and fixes the third lens 15 serving as a focus lens, slides on the inner diameter portion of the fixed lens barrel 16b, and moves up and down as indicated by arrows. As a result, the third lens 15 fixed to the movable lens barrel 16c moves up and down to function as an autofocus. Further, the vertical movement of the movable lens barrel 16c is performed by an actuator 17 using a flat stepping motor or the like provided on the side surface of the frame unit 16. The diaphragm 13 can be replaced by a lid 16d provided with an opening 16e, and the size of the opening 16e may be set to the amount of the diaphragm.

  Here, the diaphragm 13 is a diaphragm having a constant diaphragm amount, and the size of the aperture 13a of the diaphragm 13 sets the diaphragm amount of light. The size of the opening 13a is constant and the amount of light passing is limited to a constant value. If the aperture amount of the aperture 13 is constant, the amount of shooting light entering the camera varies depending on the brightness or darkness of the shooting environment. The brightness of the shooting screen can be adjusted to some extent.

  Next, as shown in FIG. 2, the shutter 20 includes a dispersion type liquid crystal element 30 provided with an IR (infrared) cut filter 31. The dispersion type liquid crystal element 30 has a certain gap (gap) between the upper substrate 21 and the lower substrate 25 via spacer balls (not shown), and the dispersion type liquid crystal material 28 is sealed with a sealing material 29 in the gap. It has a sealed structure. The upper substrate 21 is provided with an upper transparent electrode 23 made of an indium oxide ITO (Indium Tin Oxide) film doped with tin on the lower surface of an upper transparent substrate 22 made of transparent glass. The lower substrate 25 has a structure in which a lower transparent electrode 27 made of an ITO film of indium oxide doped with tin is provided on the upper surface of a lower transparent substrate made of transparent glass. Although not shown in the drawing, either the upper transparent substrate 22 or the lower transparent substrate 26 has an extended portion in a part, and the extended electrode pattern connected to the upper transparent electrode 23 in the extended portion A lead electrode pattern connected to the lower transparent electrode 27 is provided in a collective manner, and a voltage is applied to the upper transparent electrode 23 and the lower transparent electrode 27 via the lead electrode pattern. An IR (infrared) cut filter 31 is provided on the upper surface of the upper transparent substrate 22 of the dispersion type liquid crystal element 30 having the above-described configuration. The IR cut filter 31 protects the image sensor disposed below the dispersive liquid crystal element 30 from infrared rays, and prevents the received image from becoming pink (purple) due to the influence of the infrared rays of the image sensor. It is provided for.

  A PNLC mode liquid crystal material is used as the dispersion type liquid crystal material 28. This is a mixed material of a polymer material (monomer) and a liquid crystal material (for example, nematic liquid crystal material). The monomer is polymerized by ultraviolet irradiation to form a three-dimensional network polymer network. The liquid crystal material is dispersed. When a voltage is applied to the upper and lower transparent electrodes, the liquid crystal molecules sandwiched between them are aligned in the direction perpendicular to the electrodes by the electric field strength of the applied voltage, and the refractive index of the liquid crystal molecules and the polymer network shape The refractive index of the resin becomes the same, and the resin enters a transparent state and transmits light. On the other hand, in a state where no voltage is applied, the major axis of the liquid crystal molecules is aligned in a random direction, and is in a state similar to that aligned in an irregular direction when viewed macroscopically. . For this reason, the refractive index of the liquid crystal molecules and the refractive index of the polymer network resin are different, and light scattering occurs. Therefore, in a state where no voltage is applied, a light scattering state appears and a cloudy color appears. In FIG. 2, the part indicated by A corresponds to the part where the upper transparent electrode 23 and the lower transparent electrode 27 face each other, and a voltage is applied to the upper transparent electrode 23 and the lower transparent electrode 27. The area becomes transparent. And light permeate | transmits. The portion outside A is in a cloudy state and does not transmit light. Further, when no voltage is applied, the portion A and the other portions are in a cloudy state and light is not transmitted. If the upper transparent electrode 23 and the lower transparent electrode 27 are provided in the whole area (the whole liquid crystal material to be sealed), the whole area excluding the sealing material 29 can be transmitted and impermeable by voltage application ON-OFF. A wide range of shutter functions can be obtained.

  PNLCD, PDLCD, NCAP, PSCT, etc. are known as dispersive liquid crystals that exhibit light transmission (transparent) and light scattering (white turbidity) depending on the presence or absence of an electric field. In the present invention, however, the device gap is small. A PNLCD that requires a small amount of applied voltage, that is, a PNLC mode liquid crystal is used. Since the voltage to be used is small, it consumes less power and has a long battery life.

  Here, as the upper transparent substrate 22 and the lower transparent substrate 26, transparent glass having a thickness in the range of 0.2 to 1.1 mm is used. As the glass, glass such as soda glass, quartz glass, borosilicate glass, or ordinary plate glass can be used, but a plastic plate or the like can be used as other than glass.

  Next, the upper transparent electrode 23 and the lower transparent electrode 27 made of an ITO film are formed on the entire surface by a method such as a vacuum deposition method, a sputtering method, or an ion plating method. Form into shape.

  A gap (gap) between the upper substrate 21 and the lower substrate 25 is provided in a range of 3 to 10 μm. Although not shown, this gap is provided by providing a spacer ball having a required particle diameter between the upper substrate 21 and the lower substrate 25. As the spacer balls, silica balls, fiber glass, plastic balls or the like are used.

  The sealing material 29 is made of, for example, printing ink in which spacer balls (having the same diameter as the spacer balls disposed in the gap between the upper substrate 21 and the lower substrate 25) are dispersed in a thermosetting epoxy resin.

This polymer dispersion type liquid crystal device is formed as follows. First, the sealing material 29 is printed on one of the upper substrate 21 and the lower substrate 25 by a method such as screen printing, the upper substrate 21 and the lower substrate 25 are arranged to face each other, and a pressure device such as an air bag is provided. The sealing material 29 is cured by applying heat treatment while applying pressure. As the pressurizing / heating conditions, the applied pressure is about 200 g / cm ² , and the heating temperature is 150 to 160 ° C. for about 60 to 90 minutes. The sealing material 29 is printed by providing an opening serving as a liquid crystal material inlet in part. Next, a mixed material of a monomer and a liquid crystal material is injected from the opening by a vacuum injection method using a vacuum injector. Next, the liquid crystal element into which the mixed material has been injected is pressurized with a pressure device, the mixed material overflowing from the opening is wiped off, and a sealing agent made of an ultraviolet curable resin is applied dropwise to the opening with a dispenser or the like, Under reduced pressure, the sealing agent is slightly drawn into the layer, and in this state, the sealing agent is cured by irradiating with ultraviolet rays, and the monomer is brought into a polymer network state. Although the irradiation conditions of ultraviolet rays differ depending on the characteristics of the element, the conditions are generally set within the range of intensity 20 to 80 mW / cm ² , time 15 to 120 seconds, and temperature 15 to 40 degrees.

  By adopting the above forming method, a polymer dispersed liquid crystal element can be manufactured. This polymer-dispersed liquid crystal element can be made thin because no polarizing plate or alignment film is used. If 0.2 mm thick glass is used, a very thin liquid crystal element can be formed with a thickness of about 0.4 mm. Can be formed.

In the first embodiment, the IR cut filter 31 is configured by directly coating an IR cut vapor deposition film on the upper transparent substrate 22. The IR cut vapor deposition film is formed by laminating a thin film with a low refractive material (for example, SiO ₂ , MgF _2, etc.) and a thin film with a high refractive material (for example, ZrO ₂ , TiO ₂ , Ta ₂ O _5, etc.). It is formed by overlapping multiple layers. By providing the IR cut filter 31 directly on the glass surface of the dispersive liquid crystal element, the shutter 20 is very thin.

  A shutter 20 composed of a dispersive liquid crystal element 30 provided with the IR cut filter 31 is disposed between the lens barrel 16 and the imaging member 19. The front part of the imaging member 19 is provided with a required air space for image formation. Then, a shutter 20 composed of a dispersion type liquid crystal element 30 is arranged in this air space. Since the dispersive liquid crystal element 30 of the shutter 20 is formed so as to be very thin, it can be disposed in the air space in front of the imaging member 19 without hindering the thinning.

  The dispersive liquid crystal element 30 forming the shutter 20 is used in a light transmissive state by applying a required voltage to display a photographed image to make it transparent. The photographing light P incident on the opening 16e of the frame unit 16 is transmitted through the first lens 12, the diaphragm 13, the second lens 14, and the third lens 15, and is transmitted through the transmissive shutter 20 to be photographed on the imaging member 19. The image is formed and displayed on a separate display image device (not shown). When the photographed image is taken, the third lens 15 in the frame unit 16 is moved by pressing the shutter switch, the autofocus function is activated, and the focal length is adjusted. At the same time, the operation of voltage application OFF-ON-OFF to the dispersive liquid crystal element 30 is performed, and the liquid crystal white turbid state-transparent state-white turbid state is repeated, and accordingly, light non-transmission-transmission-non-transmission occurs. Done instantaneously. Then, a still image in a focused state is taken as a photograph when it is transmitted.

  Here, the size of the light transmitting portion of the dispersion-type liquid crystal element 30, that is, the portion A shown in FIG. 2 is set so that the light reaches the entire imaging member 19. The size of the portion A can be freely changed according to the size formed by the upper transparent electrode 23 and the lower transparent electrode 27, and can be handled without changing the thickness of the dispersion type liquid crystal element.

  As described above, the dispersive liquid crystal element 30 is used as the shutter 20 and is disposed between the frame unit 16 and the imaging member 19, and the dispersive liquid crystal element 30 is directly provided with the IR cut filter 31. As a result, the mechanical shutter provided on the upper part of the frame unit in the prior art can be eliminated. Since the conventional mechanical shutter has a thickness of about 1 mm, the thickness can be reduced to about 1 mm by eliminating the mechanical shutter. Further, since the space required for opening and closing the shutter blades in the prior art is not required, an effect of miniaturization is produced. Further, since the IR cut filter 31 is provided, the imaging member 19 is protected from infrared rays.

  In addition, the dispersion type liquid crystal element 30 is light in weight because it has few components and has a simple structure. Even if it is disposed at the front of the imaging member 19, the weight balance is not lost, and a stable state can be maintained. Further, a cost reduction effect can be obtained from a complicated mechanical shutter having a conventional structure.

  In the first embodiment, the IR cut filter 31 is configured by directly coating the IR cut vapor deposition film on the upper transparent substrate 22, but the IR cut filter 31 is not limited to the IR cut vapor deposition film. . Since a filter dedicated for IR cut and a filter provided with an IR cut vapor deposition film on a glass substrate are also commercially available, these may be used by being attached to the upper transparent substrate 22 via an adhesive.

  In the first embodiment, the dispersion type liquid crystal element is formed in a rectangular shape, but there is no problem even if it is formed in a circular shape in accordance with the round shape of the lens.

  Although not shown, in FIG. 1A, the shutter 20 and the imaging member 19 are shielded so that light other than photographing light entering through the frame unit 16 does not enter.

  Next, an imaging structure of a camera according to the second embodiment of the present invention will be described with reference to FIGS. Note that the imaging structure of the camera according to the first embodiment is the imaging structure of a camera for a mobile phone. FIG. 3 shows a layout of the main components of the imaging structure of the camera according to the second embodiment of the present invention and a cross-sectional view of the main part of the lens barrel unit. FIG. The perspective view which shows arrangement | positioning, (b) of FIG. 3 has shown principal part sectional drawing of the lens-barrel unit in (a) of FIG. 4 shows a plan view and a main part sectional view of the diaphragm in FIG. 3. FIG. 4A is a plan view and FIG. 4B is a main part sectional view. 5 shows a cross-sectional view of the main part of the liquid crystal lens in FIG. 3, and FIG. 6 shows a plan view showing the shape of the upper transparent electrode in FIG.

  The feature of the imaging structure of the camera according to the second embodiment is that, in contrast to the imaging structure of the first embodiment described above, the structure is changed to a circular barrel unit by eliminating the square frame unit. . That is, as shown in FIG. 3A, the lens barrel unit 36, the shutter 20, and the imaging member 19 are arranged toward the photographing light P, and the lens barrel unit 36 has a circular shape. As shown in FIG. 3B, the lens barrel unit 36 here is a liquid crystal in which a first lens 32 and a diaphragm 33 are integrally provided with a spacer 36b sandwiched in a cylindrical lens barrel 36a. The lens 40, the second lens 34, and the third lens 35 are arranged in this order. A liquid crystal lens 40 having a focus function is newly added, and an actuator for moving the lens is eliminated.

  In this structure, the liquid crystal lens 40 functions as a focus lens that adjusts the focal length. The liquid crystal lens 40 has a structure in which the liquid crystal lens 40 is disposed at the rear portion of the diaphragm 33 and integrally with the diaphragm 33.

  The shutter 20 and the imaging member 19 in the second embodiment are of the same specifications as the shutter and imaging member in the first embodiment, and the shutter 20 is the same as the shutter of the first embodiment. The dispersion type liquid crystal element is provided with an IR cut filter. The imaging member 19 uses a solid-state image sensor such as a CCD or a CMOS. Therefore, detailed description of the component parts having the same specification is omitted, and here, the lens barrel portion having a different configuration and structure will be mainly described.

  The lens barrel unit 36 is configured by housing a first lens 32, a liquid crystal lens 40 with a diaphragm 33, a second lens 34, and a third lens 35 with a spacer 36b interposed in a circular cylindrical lens barrel 36a. . And it consists of what was covered with the lid | cover 36d which provided the opening part 36e for taking in the imaging | photography light P. As shown in FIG. The spacer 36b is used for positioning and fixing the first lens 32, the liquid crystal lens 40 with the diaphragm 33, the second lens 34, and the third lens 35 in the lens barrel 36a. It has become.

  Here, the diaphragm 33 is integrally bonded and fixed to the liquid crystal lens 40 with an adhesive. The integrated diaphragm 33 and liquid crystal lens 40 are disposed between the first lens 32 and the second lens 34. This diaphragm 33 adjusts the amount of light passing therethrough. As shown in FIG. 4, the diaphragm 33 of the second embodiment is made of a film provided with a light shielding film 33b, and has a ring shape having a circular opening 33a at the center thereof. The opening 33a forms a light transmission part. In FIG. 4, N indicated by the diameter of the opening 33a indicates the opening amount of the opening 33a, and the amount of light passing is determined by the size of the opening amount N. Here, the opening amount N is set to be constant and is a certain opening amount. By making the opening amount N constant, the brightness of the photographed image can be adjusted to some extent by software on the circuit even if the light quantity is insufficient.

The diaphragm 33 in the second embodiment uses a polyethylene terephthalate film excellent in moisture resistance, heat resistance, impact resistance, chemical resistance, etc., and a light shielding film 33b made of a chromium oxide (CrO) metal film on the surface thereof. It consists of things. This chromium oxide (CrO) metal film can be formed by a method such as a vacuum deposition method, a sputtering method, or an ion plating method. For example, when formed by a vacuum deposition method or the like, An adherend (film) is placed, and the pressure during vapor deposition in the chamber of the vacuum vapor deposition machine is set to 1 × 10 ^{−6 to} 5 × 10 ⁻⁵ torr (1.33 × 10 ^{−4 to} 6.65 × 10 ^−3. It can be obtained by performing vapor deposition until the required thickness is set within the range of Pa). Since the film thickness is determined by time, the vapor deposition operation is performed under time management. The thickness may be any thickness that does not transmit light, and a thickness of 500 mm or more is sufficient. The light shielding film 33b is not limited to a chromium oxide (CrO) metal film, and may be formed of a black coating film or the like. The black coating film can be formed by a method such as a printing method, a spray coating method, or a roll coater method.

  The diaphragm 24 may be formed of a thin metal plate provided with a light shielding film, which is limited to a film provided with a light shielding film by making the opening amount N constant. However, it is more preferable to use a film in consideration of lightness and damage to other components due to component contact. The film is not limited to a polyethylene terephthalate film, but a film excellent in moisture resistance, heat resistance, impact resistance, chemical resistance, and the like is good. Polycarbonate films and polyethylene films can also be used. Further, the film thickness of 0.05 to 0.35 mm is easy to handle and is suitable because it can be thinned.

  Next, as shown in FIG. 5, the liquid crystal lens 40 is formed by laminating two liquid crystal cells, a first liquid crystal cell 40-1 and a second liquid crystal cell 40-2. The first liquid crystal cell 40-1 and the second liquid crystal cell 40-2 are shared. The liquid crystal lens 40 has a round circular shape. The first liquid crystal cell 40-1 is arranged facing the incident direction of the photographing light P, and the diaphragm 33 is integrally provided on the upper surface side on the first liquid crystal cell 40-1 side via an adhesive.

  The first liquid crystal cell 40-1 is configured by sealing a liquid crystal 49 with a sealing material 50 in the gap between the upper substrate 41A and the lower substrate 45. Further, the second liquid crystal cell 40-2 is also configured by sealing the liquid crystal 49 through the sealing material 50 in the gap between the upper substrate 41B and the lower substrate 55. Here, the upper substrate 41A has a configuration in which an upper transparent electrode 43 is provided on the lower surface of a circular upper transparent substrate 42 made of glass, and an upper alignment film 44a is provided thereon. The lower substrate 45 has a configuration in which a lower transparent electrode 47 is provided on the upper surface of a circular lower transparent substrate 46 made of glass, a lower alignment film 48a is provided thereon, and a lower transparent electrode 47 and a lower alignment film 48b are provided on the lower surface. I am doing. Here, the lower transparent electrode 47 provided on the upper surface of the lower transparent substrate 46 and the lower transparent electrode 47 provided on the lower surface have the same shape and the same size. Further, the lower alignment film 48a provided on the upper surface of the lower transparent substrate 46 and the lower alignment film 48b provided on the lower surface have the same shape and the same size, but are formed in a state in which the alignment direction by the rubbing process crosses just 90 °. ing. Further, in the first liquid crystal cell 40-1, the alignment direction of the upper alignment film 44a of the upper substrate 41A and the alignment direction of the lower alignment film 48a provided on the upper surface of the lower substrate 45 are parallel alignments that are opposite to each other by 180 °. It has become.

  The second liquid crystal cell 40-2 is composed of a liquid crystal 49 sealed in a gap between the upper substrate 41B and the lower substrate 45 via a sealing material 50. The upper substrate 41B is a circular upper transparent substrate made of glass. The upper transparent electrode 43 is provided on the upper surface of 42, and the upper alignment film 44b is provided thereon. Here, the upper transparent electrode 43 has the same shape and the same size as the upper transparent electrode 43 of the upper substrate 41A. The upper alignment film 44b has the same shape and size as the upper alignment film 44a of the upper substrate 41A, but only the alignment direction is 180 ° with respect to the alignment direction of the lower alignment film 48b provided on the lower surface of the lower substrate 45. The orientations are parallel orientations in different diametrically opposite directions. Accordingly, the upper substrate 41A and the upper substrate 41B have different configurations only in the alignment direction of the alignment film.

  Here, the upper transparent electrode 43 is formed of an ITO film of indium oxide doped with tin, and has a shape shown in FIG. A round circular electrode 43a is provided at the center, and a plurality of annular electrodes 43b, 43c, 43d formed concentrically around the circular electrode 43a are provided. Then, in order to apply a voltage to each of the circular electrode 43a and the plurality of annular electrodes 43b, 43c, 43d, connection electrodes 43a1, 43b1, 43c1, 43d1 connected to the circular electrode 43a and the respective annular electrodes 43b, 43c, 43d are provided. The upper transparent substrate 42 is provided at a part of the edge. Further, the outermost ring electrode 43d has a size that functions as a lens up to the outermost size of the annular electrode 43d, and the area M shown in FIG. 6 forms the functional area of the lens. Hereinafter, this M will be referred to as a lens function area M and will be described. The lens function area M is set slightly larger than the opening amount N of the diaphragm 33. Note that FIG. 6 shows the upper transparent electrode 43 divided into four electrodes for easy understanding, but the number of divisions is set as necessary. A larger number of divisions is preferable because a highly accurate phase modulation distribution can be obtained. Different voltage amounts are applied to the circular electrode 43a and the annular electrodes 43b, 43c, and 43d.

  The lower transparent electrode 47 is formed of an ITO film in the same manner as the upper transparent electrode 43, but the shape thereof is a round circular shape on one surface, and the size thereof is an annular electrode on the outermost side of the upper transparent electrode 43. The outer shape of 43d, that is, the same size as the lens function area M is formed. Although not shown, the lower transparent electrode 47 is provided with a connection electrode routed to the edge of the lower transparent substrate 46 in order to apply a voltage.

  The upper transparent electrode 43 and the lower transparent electrode 47 made of this ITO film are formed on the entire surface by a method such as a vacuum deposition method, a sputtering method, or an ion plating method, and then formed into the above shape by a photolithographic method. Form.

  The upper alignment film 44a and the lower alignment film 48a of the first liquid crystal cell 40-1 and the upper alignment film 44b and the lower alignment film 48b of the second liquid crystal cell 40-2 are formed by a polyimide resin formed by a printing method, a spin coating method, or the like. The surface of the resin film is subjected to an orientation treatment by rubbing using a cotton cloth material or the like. The upper alignment film 44a and the lower alignment film 48a of the first liquid crystal cell 40-1 are arranged in parallel alignment in opposite directions that are different in the alignment direction by 180 °, and the second liquid crystal cell 40- The two upper alignment films 44b and the lower alignment films 48b are arranged in parallel alignment in opposite directions that are 180 ° different in alignment direction. In this way, the arrangement of parallel orientation can align the light refraction direction in the same direction. In addition, the alignment directions of the first liquid crystal cell 40-1 and the second liquid crystal cell 40-2 are crossed at 90 degrees. As a result, the P-polarized light component (component having a vibration direction parallel to the incident surface to the liquid crystal cell) and the S-polarized component (component having a vibration direction perpendicular to the incident surface to the liquid crystal cell) are transmitted and used. It is possible to obtain the effect of increasing the light utilization efficiency.

  Next, the encapsulated liquid crystal 49 is a nematic liquid crystal having a homogeneous molecular arrangement, or a mixed liquid crystal in which a small amount of chiral nematic liquid crystal is mixed with the nematic liquid crystal.

  The sealing material 50 is formed by dispersing spacers made of silica balls in a thermosetting epoxy resin. This spacer is provided in order to provide a required cell gap. In the second embodiment, the cell gap is set to 20 μm using silica balls having a particle diameter of 20 μm. The cell gap affects the response speed of the alignment rising reaction and falling reaction of the liquid crystal molecules when the voltage application is ON / OFF. When the cell gap is small, the response speed of the rise and fall of the liquid crystal molecules is fast. On the other hand, when the cell gap is large, the response speed of the rise and fall of the liquid crystal molecules is slow. In the present embodiment, the cell gap is set to 20 μm, but from the results of various experiments, the cell gap has a preferable range of 10 to 50 μm.

  The round upper transparent substrate 42 and lower transparent substrate 46 are made of transparent glass having a thickness in the range of 0.15 to 1.1 mm. As the glass, glass such as soda glass, quartz glass, borosilicate glass, or ordinary plate glass can be used, but a plastic plate or the like can be used as other than glass. Although the glass having a desired thickness can be used by polishing or the like, it is preferable to use a glass having a thickness of 0.15 mm or more in consideration of cracks caused by impact. In the present embodiment, the upper transparent substrate 42 is 0.15 mm, and the lower transparent substrate 46 is 0.3 mm. The total thickness of the liquid crystal lens 40 is about 0.6 mm. The upper transparent substrate 42 and the lower transparent substrate 46 are used after being scribed into a circular shape.

  This liquid crystal lens 40 is formed by printing the sealing material 50 on either the upper substrate 41A, 41B or the lower substrate 45 by a screen printing method or the like, and the alignment directions of the upper and lower alignment films 44a and 48a are parallel alignment, and The upper and lower alignment films 44b and 48b are aligned in parallel, and the upper substrate 41A, the lower substrate 45, and the upper substrate 41B are combined and bonded together under pressure and heating. Next, the liquid crystal 49 is injected by a vacuum injection method from an opening provided in one place of the sealing material 50 of each of the first liquid crystal cell 40-1 and the second liquid crystal cell 40-2, and the opening is UV cured after the injection. By sealing with resin, the liquid crystal lens 40 is completed.

  The liquid crystal lens 40 having the above configuration applies different voltages to the circular electrode of the liquid crystal lens 40 and a plurality of annular electrodes surrounding the circular electrode, changes the alignment direction of the liquid crystal molecules for each electrode, and transmits through the electrodes. It functions as an autofocus function that adjusts the focal length by applying phase modulation to the light. Accordingly, based on the data signal obtained by automatically measuring the distance to the photographic body, a drive instruction signal for each applied voltage is issued in the control circuit, the liquid crystal lens 40 is driven via each connection electrode, and the focus The distance is adjusted automatically.

  Further, the liquid crystal lens 40 is disposed at the rear of the diaphragm 33 so as to be integrated with the diaphragm 33. The lens function area M of the liquid crystal lens 40 is set to a value slightly larger than the opening amount N of the diaphragm 33, and all light passing through the opening 33 a of the diaphragm 33 passes through the lens function area M of the liquid crystal lens 40. Since the aperture amount N of the diaphragm 33 is the place that most restricts the amount of light passing through, the lens function area M can be set to the most limited minimum area. As a result, the amount of phase modulation can be increased in a small area of the lens function area M, so that the lens power can be increased. This makes it possible to adjust the focal length from a close range to a long range. Further, if the area is small, the number of annular electrodes can be reduced, and the circuit design is facilitated without being complicated.

  The liquid crystal lens 40 has an autofocus function. Accordingly, the first lens 32, the second lens 34, the third lens 35, and the liquid crystal lens 40 with the diaphragm 33 can be fixed in the lens barrel. Therefore, in the conventional structure, an actuator or the like is used for moving the lens, but in the present invention, no actuator is required. The number of parts can be reduced and the cost can be considerably reduced. Moreover, since the structure itself is a simple structure and unitized, handling and the like become easy.

  Further, it is possible to reduce the size by eliminating the actuator and forming the lens barrel unit in a circular shape.

  Furthermore, in the second embodiment, the liquid crystal lens 40 is formed in a round and circular shape. The first lens 32, the second lens 34, and the third lens 35 are most easily formed in a circular shape, and a highly accurate lens can be obtained. By forming the liquid crystal lens 40 in a circular shape like the first lens 32, the second lens 34, and the third lens 35, the lens barrel 36a, the lid 36d, and the spacer 36b for storing these components are also round. Can be formed. Since the circular shape makes it easier to manufacture molds and parts, it can also reduce the manufacturing cost. In addition, effects such as ease of assembly of the lens barrel unit also appear.

  In the second embodiment, the liquid crystal lens 40 with the diaphragm 33 is disposed between the first lens 32 and the second lens 34. The liquid crystal lens 40 with the diaphragm 33 is disposed in front of the first lens 32, that is, It is also possible to arrange between the lid 36d and the first lens 32. In that case, it is possible to use the lid 36d as a diaphragm instead of the diaphragm 33. The liquid crystal lens 40 is brought close to the lid 36d, and the opening 36e of the lid 36d is used as the aperture of the diaphragm.

  Although explanation is omitted, since the shutter 20 having the same specifications as the shutter in the first embodiment is used, it is needless to say that the same effect as that explained in the first embodiment can be obtained.

  Next, an imaging structure of a lens according to the third embodiment of the present invention will be described with reference to FIGS. Here, FIG. 7 shows a layout of the main components of the imaging structure of the camera according to the third embodiment of the present invention and a cross-sectional view of the main part of the lens barrel. FIG. 7A shows the main components. The perspective view which shows arrangement | positioning, (b) of FIG. 7 has shown principal part sectional drawing of the lens-barrel unit in (a) of FIG. FIG. 8 shows a cross-sectional view of the main part of the shutter in FIG.

  The imaging structure of the lens in the third embodiment has an arrangement structure in which the lens barrel unit 56 and the imaging member 19 are sequentially arranged toward the photographing light P as shown in FIG. Since the imaging member 19 here uses an imaging member having the same specifications as the imaging member used in the first embodiment and the second embodiment, the same reference numerals are given. The photographing light P enters the lens barrel unit 56, the focal length is adjusted in the lens barrel unit 56, and an image is formed at the imaging member 19. A significant difference from the imaging structure in the second embodiment described above is that the shutter is housed in the lens barrel unit 56. Hereinafter, the imaging structure of the third embodiment will be described with a focus on differences from the second embodiment.

  The lens barrel unit 56 includes a circular cylindrical lens barrel 56a, a shutter 80, a first lens 32, a liquid crystal lens 40 with an aperture 33, a second lens 34, and a third lens 35 housed in the lens barrel 56a. The cover 56d has an opening 56e that transmits the photographing light P, and a plurality of spacers 56b. Inside the lens barrel 56a, the shutter 80, the first lens 32, the liquid crystal lens 40 with a diaphragm 33, the second lens 34, and the third lens 35 are stored in this order in the direction in which the photographing light P is incident. Has been. These components are arranged at a required position interval with spacers 56b having different thicknesses. Here, the first lens 32, the liquid crystal lens 40 with the diaphragm 33, the second lens 34, and the third lens 35 are the specifications of the first lens, the liquid crystal lens with the diaphragm, the second lens, and the third lens in the second embodiment. Since the same specifications are used, the same reference numerals are given. Therefore, detailed description of components having the same specifications as those of the second embodiment is omitted here. The liquid crystal lens 40 functions as an autofocus function as described in the second embodiment.

  A feature of the imaging structure in the third embodiment is that the shutter 80 is housed in the barrel unit 56 and disposed in the front portion of the first lens 32. That is, it is disposed at a position immediately adjacent to the opening 56e where the photographing light P enters the lens barrel 56a. The shutter 80 is configured by providing an IR cut filter 71 in the dispersion type liquid crystal element 60. The shutter 80 of the third embodiment has a round outer shape, and the size is also in the lens barrel 56a. It is smaller as long as it fits in

  The shutter 80 has a configuration formed under the same specifications as the shutter described in the first embodiment, but the outer shape is round. That is, as shown in FIG. 8, the shutter 80 comprises a dispersion type liquid crystal element 60 provided with an IR (infrared) cut filter 71. The dispersion type liquid crystal element 60 has an upper substrate 61 and a lower substrate 65 connected to spacer balls. A certain gap (gap) is provided through (not shown), and the dispersive liquid crystal material 68 is sealed with the sealing material 69 in the gap. Here, the upper substrate 61 is formed by providing an upper transparent electrode 63 made of an ITO film on the lower surface of a round upper transparent substrate 62 made of transparent glass, and the lower substrate 65 is a round lower plate made of transparent glass. The lower transparent electrode 67 made of an ITO film is provided on the upper surface of the transparent substrate 66. The upper transparent electrode 63 and the lower transparent electrode 67 are circular and have a shape formed on one surface.

  The dispersive liquid crystal material 68 here is the same as the liquid crystal material used in the first embodiment, and uses a PNLC mode liquid crystal material. This is a mixed material of a polymer material (monomer) and a liquid crystal material (for example, nematic liquid crystal material). The monomer is polymerized by ultraviolet irradiation to form a three-dimensional network polymer network. The liquid crystal material is dispersed.

  When the application of voltage to the dispersive liquid crystal element 60 is driven OFF-ON-OFF, the liquid crystal is repeatedly in the white turbid state-transparent state-white turbid state, and accordingly, the photographing light is not transmitted, transmitted, transmitted, or transmitted. Done instantaneously. That is, the dispersed liquid crystal element 60 functions as a shutter.

The IR cut filter 71 is configured by directly coating an IR cut vapor deposition film on the upper transparent substrate 62 with the same specifications as the IR cut filter of the first embodiment. The IR cut vapor deposition film is formed by laminating a thin film with a low refractive material (for example, SiO ₂ , MgF _2, etc.) and a thin film with a high refractive material (for example, ZrO ₂ , TiO ₂ , Ta ₂ O _5, etc.). It is formed by overlapping multiple layers. By providing the IR cut filter 71 directly on the glass surface of the dispersion type liquid crystal element, the thickness of the shutter 80 is reduced.

  Here, the shutter 80 is constituted by a dispersion-type liquid crystal element 60 having a circular shape and provided with an IR cut filter 71, and is formed in a size that can be accommodated in the lens barrel 56a. If such a structure is taken, the size of the shutter 80 can be made considerably smaller than the structure arranged immediately before the imaging member 19. Less material is used, resulting in a reduction in material costs. In addition, the shutter 80 is disposed in front of the first lens 32 in the lens barrel 56. This is a structure in which the infrared ray is cut at the farthest position from the imaging member 19 in the lens barrel 56a. The effect of infrared rays on the imaging member 19 can be reduced by cutting the infrared rays at a position slightly farther than cutting just before the imaging member 19. In the present invention, a liquid crystal material is used for the shutter 80 and the liquid crystal lens 40. In liquid crystal materials, changes in the reaction rate appear due to the temperature effect of infrared rays. By cutting infrared rays at the shutter 80 and the front part of the liquid crystal lens 40, a change in the reaction speed of the liquid crystal material is reduced, and a stable reaction speed can be obtained. Further, the shutter 80 is housed in the lens barrel 56a to prevent damage due to impact or the like.

  By adopting the above structure, the thickness of the mechanical shutter can be considerably reduced by performing the function of the mechanical shutter with a distributed liquid crystal element, compared to the structure in which the mechanical shutter is arranged at the front part of the lens barrel in the prior art. Get the effect of Furthermore, since components other than the imaging member are housed in the lens barrel and unitized, the cost can be reduced with ease of handling and assembly.

  Further, the shutter 80 is formed in a circular shape like the first lens 32, the liquid crystal lens 40, the second lens 34, the third lens 35, etc., so that a lens barrel 56a and a lid for housing these components are formed. 56d and the spacer 56b can also be formed in a round shape. The circular shape makes it easy to manufacture molds and parts, and also reduces the manufacturing cost. In addition, effects such as ease of assembly of the lens barrel also appear.

  The imaging structure of the camera-equipped mobile phone has been described above as an embodiment. However, the imaging structure of the camera of the present invention can be applied to any camera that uses a fixed aperture value.

  Although explanation is omitted, since the liquid crystal lens having the same specifications as the liquid crystal lens in the second embodiment is used, it goes without saying that the same effect as that explained in the second embodiment can be obtained.

FIG. 1A is a perspective view showing an arrangement of main components, FIG. 1A is a layout diagram of main components of the imaging structure of the camera according to the first embodiment of the present invention, and a cross-sectional view of the main part of the frame unit; FIG. 1B is a cross-sectional view of the main part of the frame unit in FIG. It is principal part sectional drawing of the shutter in FIG. FIG. 3A is a perspective view showing an arrangement of main components, and FIG. 3A is a layout view of main components of the imaging structure of the camera according to the second embodiment of the present invention and a cross-sectional view of the main part of the barrel unit. FIG. 3B is a cross-sectional view of the main part of the lens barrel unit in FIG. 4A and 4B are a plan view and a main part sectional view of the diaphragm in FIG. 3, in which FIG. 4A is a plan view and FIG. 4B is a main part sectional view. It is principal part sectional drawing of the liquid crystal lens in FIG. It is the top view which showed the shape of the upper transparent electrode in FIG. FIG. 7A is a perspective view showing an arrangement of main components, and FIG. 7A is an arrangement diagram of main components of the imaging structure of the camera according to the third embodiment of the present invention and a cross-sectional view of the main part of the barrel unit. FIG. 7B is a cross-sectional view of the main part of the lens barrel unit in FIG. FIG. 8 is a cross-sectional view of the main part of the shutter in FIG. 7. 9A and 9B are layout diagrams of main components schematically showing an example of a conventional structure of a camera of a camera-equipped mobile phone. FIG. 9A is a perspective view showing the layout of main components, and FIG. ) Shows a cross-sectional view of the main part of the frame unit in (a).

Explanation of symbols

12, 32 First lens 13, 33 Aperture 13a, 33a Aperture 14, 34 Second lens 15, 35 Third lens 16 Frame unit 16a Frame 16b Fixed lens barrel 16c Moving lens barrel 16d, 36d, 56d Lids 16e, 36e, 56e Aperture 17 Actuator 19 Imaging member 20, 80 Shutter 21, 41A, 41B, 61 Upper substrate 22, 42, 62 Upper transparent substrate 23, 43, 63 Upper transparent electrode 25, 45, 65 Lower substrate 26, 46, 66 Lower Transparent substrates 27, 47, 67 Lower transparent electrodes 28, 68 Dispersed liquid crystal materials 29, 50, 69 Sealing materials 30, 60 Dispersed liquid crystal elements 31, 71 IR cut filter 33b Light shielding films 36, 56 Lens barrel units 36a, 56a Lens tube 36b, 56b Spacer 40 Liquid crystal lens 40-1 First liquid crystal cell 40-2 Second liquid crystal cell 43 a circular electrodes 43b, 43c, 43d annular electrodes 43a1, 43b1, 43c1, 43d1 connection electrodes 44a, 44b upper alignment film 48a, 48b lower alignment film 49 liquid crystal N aperture M lens functional area P photographing light

Claims (6)

In an imaging structure of a camera having at least a plurality of photographing lenses, a shutter, an aperture, and an imaging member, the shutter is constituted by a dispersion type liquid crystal element, and the dispersion type liquid crystal element is disposed in front of the imaging member. An imaging structure of a camera, wherein an IR (infrared) cut filter is provided on the dispersion type liquid crystal element. In an imaging structure of a camera having at least a plurality of photographing lenses, a shutter, a diaphragm, and an imaging member, a liquid crystal lens having a focus function is disposed integrally with the diaphragm, and the shutter is configured by a distributed liquid crystal element. An image pickup structure for a camera, wherein the dispersive liquid crystal element is disposed in front of the imaging member and an IR (infrared) cut filter is provided on the dispersive liquid crystal element. 3. The camera imaging structure according to claim 1, wherein the dispersion type liquid crystal element is a liquid crystal element of a type using a PNLC mode liquid crystal. The imaging structure of the lens according to claim 2, wherein the liquid crystal lens has a circular outer shape. 5. The lens imaging structure according to claim 1, wherein the dispersive liquid crystal element is housed in a lens barrel together with the photographing lens and the diaphragm. 6. The imaging structure of a lens according to claim 1, wherein the dispersive liquid crystal element has a circular outer shape.

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