JP2005202185A - Light control device, method for manufacturing the same, and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve commercial values and performance of a light control device and an imaging device using a liquid crystal (optical) element by drastically improving the effective use rate of a liquid crystal material in a liquid crystal injection process, and inexpensively manufacturing even a liquid crystal light control element composed of a GH cell filled with an expensive guest-host type liquid crystal material with high precision. <P>SOLUTION: In the case of manufacturing the light modulating device provided with the GH cell 52 in which a pair of transparent substrates 31a, 31b respectively having electrodes (operating electrodes) 32a, 32b are arranged oppositely to each other on the electrode sides and the liquid crystal material 34 is sealed in a gap between the substrates, the liquid crystal material 34 in just the right amount is dropped on the lower substrate 31a in the vicinity of an injection hole 57 in an empty cell state, and subsequently the cell is inclined under vacuum suction, the liquid crystal material 34 is allowed to flow on the lower substrate 31a so as to close the injection hole 57 and the liquid crystal material 34 is filled in a gap between the pair of substrates from the injection hole 57 further by returning inside pressure to atmospheric pressure and utilizing a pressure difference between the inside and the outside of the gap. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light control device using a liquid crystal element for adjusting and emitting the amount of incident light, a manufacturing method thereof, and an imaging device using the light control device.

  Usually, a polarizing plate is used for a light control device using a liquid crystal optical element (liquid crystal cell). As this liquid crystal cell, for example, a TN (Twisted Nematic) liquid crystal cell or a guest-host (GH (Guest Host)) liquid crystal cell is used.

  FIG. 14 is a schematic explanatory diagram showing the operation principle of a light control device using a conventional GH cell. This light control device mainly includes a polarizing plate 11 and a GH cell 12A. In the GH cell 12A, a liquid crystal mixture is sealed between two glass substrates (not shown), and an operation electrode and a liquid crystal alignment film (not shown) are provided.

  The liquid crystal mixture is composed of liquid crystal molecules 13 A and dichroic dye molecules 14. The liquid crystal molecules 13A as the host material are positive type (positive type) having positive dielectric anisotropy. The dichroic dye molecule 14 as a guest material has anisotropy in light absorption, and may be positive (p-type) or negative (n-type). FIG. 14 shows an example in which the dichroic dye molecule 14 is a positive (p-type) dye molecule that absorbs light in the long axis direction of the molecule.

  The incident light 5 is selected when passing through the polarizing plate 11 and changes to linearly polarized light. Further, in the GH cell 12A, the alignment process is performed so that the liquid crystal molecules 13A are aligned in the same direction as the vibration direction of the linearly polarized light (vertical direction in FIG. 14) when no voltage is applied.

  FIG. 14A shows the state of the GH cell 12A when no voltage is applied. Under the influence of the liquid crystal molecules 13A, the dichroic dye molecules 14 are also oriented in the same direction, and the vibration direction of linearly polarized light coincides with the molecular long axis direction of the dichroic dye molecules 14, so that the polarized light is dichroic dye. It is easily absorbed by the molecule 14. Therefore, in the state where no voltage is applied in FIG. 14A, the light transmittance of the GH cell 12A is low.

  On the other hand, FIG. 14B shows the state of the GH cell 12A when a voltage is applied. When a voltage is applied to the GH cell 12A, the liquid crystal molecules 13A are aligned in the electric field direction, and accordingly, the molecular long axis direction of the dichroic dye molecules 14 is orthogonal to the polarization vibration direction. For this reason, polarized light is hardly absorbed by the dichroic dye molecule 14 and transmitted. Accordingly, in the voltage application state shown in FIG. 14B, the light transmittance of the GH cell 12A is high.

  As the dichroic dye molecule 14, a negative (n-type) dye molecule that absorbs light in the molecular minor axis direction can also be used. In this case, the light transmittance is opposite to the case of using positive type dye molecules, and light is not easily absorbed when no voltage is applied, and light is easily absorbed when a voltage is applied.

  In the light control device shown in FIG. 14, the absorbance ratio between when a voltage is applied and when no voltage is applied, that is, the optical density ratio is about 10. This has an optical density ratio that is approximately twice that of a light control device that includes only the GH cell 12A without using the polarizing plate 11.

  When a rectangular driving pulse is applied to the GH cell 12A, the average light transmittance of the light control device shown in FIG. 14 (value in air: an empty liquid crystal cell and a polarizing plate are placed in the optical path. As shown in FIG. 15, although the transmittance at the time was set as a reference (= 100%), the same was applied), the drive pulse voltage was increased to 10V, although it increased as the drive pulse voltage increased. The maximum light transmittance at that time is only about 60%, and the change of the light transmittance is gradual.

  This is because, when positive type liquid crystal molecules are used as the host material, the interaction between the liquid crystal molecules and the alignment film at the interface of the alignment film is strong when no voltage is applied. It is considered that there are relatively many liquid crystal molecules that do not change or hardly change.

  Therefore, as a result of intensive studies, the present applicant has proposed a light control device using a negative liquid crystal as a host material and an image pickup device using the light control device (see Patent Document 1 described later, hereinafter, Patent Document). The invention relating to No. 1 will be referred to as the prior invention.).

  FIG. 16 is a schematic diagram showing the operation principle of the light control device based on the prior invention. This light control device mainly includes a polarizing plate 11 and a GH cell 12B. In the GH cell 12B, negative type (negative type) liquid crystal molecules 13B having negative dielectric anisotropy as a host material and positive or negative type dichroic dye molecules 14 as a guest material are encapsulated. Has been. FIG. 13 shows a case where the dichroic dye molecule 14 is a positive (p-type) pigment molecule.

  Similarly to the apparatus shown in FIG. 14, the incident light 5 is sorted when passing through the polarizing plate 11 and changes to linearly polarized light. In the GH cell 12B, when no voltage is applied, the alignment treatment is performed so that the liquid crystal molecules 13B are aligned in a direction orthogonal to the vibration direction of the linearly polarized light (left and right direction in FIG. 16).

  FIG. 16A shows the state of the GH cell 12B when no voltage is applied. The liquid crystal molecules 13B are arranged so as to be orthogonal to the substrate, and accordingly, the molecular long axis direction of the dichroic dye molecules 14 is orthogonal to the vibration direction of the polarized light, so that the polarized light is hardly absorbed by the dichroic dye molecules 14, To Penetrate. Accordingly, in the state where no voltage is applied in FIG. 16A, the light transmittance of the GH cell 12B is high.

  On the other hand, FIG. 16B shows the state of the GH cell 12B when a voltage is applied. When a voltage is applied to the GH cell 12B, the liquid crystal molecules 13B are aligned so as to be orthogonal to the electric field direction, and accordingly, the molecular long axis direction of the dichroic dye molecules 14 coincides with the polarization direction of light. . For this reason, polarized light is easily absorbed by the dichroic dye molecule 14. Therefore, in the state of voltage application shown in FIG. 16B, the light transmittance of the GH cell 12B is low.

  In addition, a negative (n-type) pigment molecule can also be used as the dichroic dye molecule. In this case, the light transmittance is opposite to that in the case of using positive type dye molecules.

  FIG. 17 is a graph illustrating the light transmittance with respect to the driving pulse voltage when a rectangular wave driving pulse is applied to the GH cell 12B of FIG. At this time, as an example of the negative type liquid crystal 13B having a negative dielectric anisotropy (Δε), MLC-6608 manufactured by Merck Co. is used as a host material, and the light absorption anisotropy (ΔA) is positive type. As an example of the chromatic dye molecule 14, D5 manufactured by BDH was used as a guest material. As shown in FIG. 17, the average light transmittance of visible light decreases from the maximum light transmittance of about 78% to about 10% as the pulse voltage increases, and the change of the light transmittance is relatively steep. became.

  The reason for this is that when negative liquid crystal molecules are used as the host material, the interaction between the liquid crystal molecules and the alignment film at the interface of the alignment film is very weak when no voltage is applied, so light is easily transmitted when no voltage is applied. In addition, it is considered that the direction of the director of the liquid crystal molecules easily changes with the application of voltage.

  Thus, according to the invention of the prior application, by constructing a guest-host type liquid crystal cell using a negative type liquid crystal as a host material, the light transmittance is improved particularly when it is transparent, the contrast is improved, and the GH cell is imaged. A compact light control device that can be used by being incorporated in an optical system can be realized.

  In this case, by further disposing the polarizing plate in the optical path of the incident light to the liquid crystal optical element, the ratio of absorbance when no voltage is applied to that when voltage is applied (that is, the ratio of optical density) is further improved, and the light control device The contrast ratio is further increased, and the dimming operation can be performed more normally from a bright place to a dark place.

  18 to 20 show structural examples of the GH cell according to the invention of the prior application, FIG. 18A is a plan view of the GH cell, and FIG. 18B is a line XVIIIB-XVIIIB in FIG. 19 is an enlarged sectional view taken along line XIX-XIX in FIG. 18A, FIG. 20A is a plan view of the lower substrate of the GH cell, and FIG. 20B is an upper sectional view of the upper substrate. It is a top view.

  The GH cell 12B includes a lower substrate (first substrate) 31a made of glass or the like having a thickness of 200 to 500 μm, and an upper substrate made of glass or the like having a smaller size than 200 to 500 μm. Second substrate) 31b. Each of these substrates is formed with ITO (Indium tin oxide) electrodes (transparent electrodes) 32a and 32b having a thickness of 15 to 120 nm and liquid crystal alignment films 33a and 33b having a thickness of 30 to 100 nm. The liquid crystal alignment films 33a and 33b are subjected to a liquid crystal alignment process by a rubbing method or the like. The lower substrate 31a is provided with lead-out portions 32c and 32d of the transparent electrodes 32a and 32b in a portion 31c that is larger than the upper substrate 31b.

  The substrates 31a and 31b are aligned and overlapped with each other facing each other on the electrodes 32a and 32b side, and injected into an empty cell formed by sealing the periphery with a main sealing material (sealing material) 35. The GH liquid crystal material 34 is injected from the hole 7, and the injection hole 7 is sealed with an end seal material (sealing material) 41.

For example, a sealing material made of a thermosetting epoxy resin containing glass fibers having a diameter of 3 μm, for example, on the cell periphery of one substrate (for example, for the lower substrate 31a) on which the transparent electrode 32a and the liquid crystal alignment film 33a are formed ( Main seal) 35 is applied with a predetermined width. Then, on the other substrate (for example, for the upper substrate 31b) on which the transparent electrode 32b and the liquid crystal alignment film 33b are formed, a plastic ball having a diameter of 3 μm, for example, is uniformly dispersed by wet spraying or dry spraying as a spacer 36. After the substrates are aligned and stacked, heat treatment is performed while applying pressure under appropriate conditions (for example, 150 to 170 ° C. and 1 to ² kg / cm ² ) using a hot press plate. Curing is completed, and the bonding of both substrates is completed. Then, the bonded substrate is separated into a pair of 31a and 31b, thereby forming an empty cell.

  The ITO electrode 32b extending outside the effective optical path 20 of the upper substrate 31b is electrically connected to the electrode lead portion 32d provided on the lower substrate 31a. Specifically, the ITO electrode 32b of the upper substrate 31b and the electrode lead portion 32d of the lower substrate 31a are connected to each other by a conductive material 26 such as carbon paste outside the sealing material 35, and the GH cell 12 Outside the effective optical path 20, conduction between substrates, that is, extraction of the transparent electrode 32 b can be performed.

As the injection process of the liquid crystal material (liquid crystal molecules + dichroic dye molecules) in the manufacturing process of such a GH cell 12B, a vacuum injection method as shown in FIG. 21 or FIG. 22 is usually used.

  FIG. 21 is a principle diagram of a method called a dip method. First, empty cells 38 made of glass substrates facing each other having a working electrode or a transparent electrode (not shown here) and a liquid crystal alignment film (not shown here) are dipped with the liquid crystal injection hole 7 facing downward. It is arranged in the device 44. The dip device 44 is provided with a container 43 that contains a liquid crystal material 34 that is a mixture of liquid crystal molecules and dichroic dye molecules. Then, after evacuating the inside of the dip device 44 together with the empty cell 38, the valve 45 is closed, the inside of the device 44 is kept in a vacuum state, and the liquid crystal injection hole 7 of the empty cell 38 is immersed in the liquid crystal material 34 of the container 43. To do. Next, when the valve 45 is opened and the inside of the dip device 44 leaks air (preferably nitrogen leak), a pressure difference is generated between the evacuated empty cell 38 and the dip device 44 opened to atmospheric pressure, A liquid crystal material 34 is injected into the empty cell 38 through the liquid crystal injection hole 7. After that, the vacuum part 8 is completely eliminated, and the GH cell 12B in which the liquid crystal material 34 is filled in the entire empty cell 38 can be obtained.

  FIG. 22 is a principle diagram of a method called a touch method. First, empty cells 38 made of glass substrates facing each other, each having a working electrode or a transparent electrode (not shown here) and a liquid crystal alignment film (not shown here), are touched with the liquid crystal injection hole 7 facing downward. Place in device 46. The touch device 46 is provided with a container 43 that contains a liquid crystal material 34 that is a mixture of liquid crystal molecules and dichroic dye molecules, and a small container 43 ′ is disposed in the container 43. Then, after the inside of the touch device 46 is evacuated together with the empty cell 38, the valve 45 is closed, the inside of the device 46 is kept in a vacuum state, and the small container 43 ′ having the liquid crystal material 34 is placed in the liquid crystal injection hole 7 of the empty cell 38. Raise to the position. Next, when the valve 45 is opened and the inside of the touch device 46 leaks air (preferably nitrogen leak), a pressure difference is generated between the evacuated empty cell 38 and the touch device 46 opened to the atmospheric pressure, A liquid crystal material 34 is injected into the empty zel 38 through the liquid crystal injection hole 7. After that, the vacuum part 8 is completely eliminated, and the GH cell 12B in which the entire empty cell 38 is filled with the liquid crystal material 34 can be obtained.

Japanese Patent Laid-Open No. 11-326894 (page 3, column 4, lines 8-18, FIG. 1)

  In any of the liquid crystal injection processes described above, the liquid crystal material 34 is sucked upward from the container by utilizing the pressure difference between the evacuated cell interior and the atmosphere outside the cell, and the liquid crystal material 34 is introduced into the cell from the injection hole 7. Although it is filled, this has the following problems.

  The amount of liquid crystal material actually injected as a component of the liquid crystal cell is smaller than the amount of liquid crystal consumed in the injection process step. In other words, because there is an extra liquid crystal material that is not taken into the cell due to adhesion to the outside of the cell without being injected into the cell, the effective utilization rate of the liquid crystal material becomes low (consumption increases). In addition, there is a problem that it is necessary to add a dedicated cell cleaning step after liquid crystal injection, which increases the manufacturing cost of the GH cell.

  In particular, the guest-host type liquid crystal material 34 used as the light control element of the image pickup apparatus is very expensive as a result (for example, a display device) by variously mixing and mixing various dyes according to the purpose. Since the effective utilization rate of such a liquid crystal material is lowered for the reason described above, the manufacturing cost of the liquid crystal cell is further increased. Accordingly, it has been eagerly desired to establish a liquid crystal injection process with high material utilization efficiency and high accuracy.

  The object of the present invention is to significantly improve the effective utilization rate of the liquid crystal material in the liquid crystal injection process step, and to achieve a low cost and high accuracy even in a liquid crystal light control device comprising a GH cell enclosing an expensive guest-host type liquid crystal material. The product value and performance of a light control device and an imaging device using a liquid crystal (optical) element are to be improved.

That is, according to the present invention, a pair of substrates (particularly a transparent substrate) such as a glass substrate each having an electrode (operating electrode) such as ITO is disposed opposite to each other on the electrode side, and a liquid crystal material is sealed in a gap between the pair of substrates. In a method of manufacturing a light control device comprising a liquid crystal element,
A step of placing a predetermined amount of liquid crystal material in the vicinity of the injection hole in a state where the liquid crystal material is not sealed, and further closing the injection hole with the liquid crystal material;
And a step of filling the liquid crystal material into the gap through the injection hole.

Further, according to the present invention, a pair of substrates (especially transparent electrodes) such as a glass substrate each having an electrode (operating electrode) such as ITO are disposed opposite to each other on the electrode side, and a liquid crystal material is sealed in a gap between the pair of substrates. In a light control device comprising a liquid crystal element,
One of the pair of bases has a portion enlarged than the other, an injection hole for the liquid crystal material is formed on the enlarged side, and the injection hole is sealed. A light control device is provided.

  Furthermore, the present invention also provides an imaging device configured by arranging the light control device of the present invention in the optical path of the imaging system.

  According to the present invention, one of the pair of bases constituting the liquid crystal element has a portion enlarged than the other, and an injection hole for the liquid crystal material is formed on the enlarged side, and The injection hole is configured to be sealed, and in a state where the liquid crystal material is not sealed, a predetermined amount of liquid crystal material is placed in the vicinity of the injection hole, and the injection hole is further blocked by the liquid crystal material, Since the liquid crystal material is filled into the gap from the injection hole, in the process of injecting the liquid crystal material into the gap, a necessary amount of the liquid crystal material is placed in the vicinity of the injection hole by dropping or the like. Can be injected from. As a result, there is almost no extra liquid crystal material that inevitably flows from the vicinity of the injection hole to the outside of the cell, which was unavoidable in the conventional injection process, and it is possible to manufacture with the minimum amount of material used. The effective utilization rate of the material can be greatly improved, for example, from about 50% to about 75%. As a result, even if an expensive guest-host type liquid crystal material is used, its manufacturing cost does not increase, and it is not necessary to add a dedicated cell cleaning step after the liquid crystal material is injected.

  In the present invention, the injection hole is formed on the side of the electrode lead portion provided on at least one of the pair of substrates, and an appropriate amount of the liquid crystal material is dropped on the substrate in the vicinity of the injection hole, and the atmosphere is decompressed. The liquid crystal material is moved on the substrate by, for example, tilting the substrate (or empty cell) to close the injection hole with the liquid crystal material, and then the reduced pressure state of the atmosphere is relaxed, and the internal space between the pair of substrates is reduced. Preferably, the liquid crystal material is filled into the gap from the injection hole by a pressure difference between the liquid crystal and the outside.

  In this case, in the state of an empty cell before liquid crystal injection, the substrate surface near the injection hole where the liquid crystal material is dropped on the electrode lead-out side is irradiated with ultraviolet rays (UV ozone cleaning), plasma treatment, and laser light irradiation. If at least one of the treatments is performed, the surface of the substrate is cleaned, the organic compounds that are the main sources of contamination are decomposed and the contaminated particles are physically removed, and the liquid crystal material dropped in the subsequent process is injected by tilting or the like. It can slide smoothly toward the hole. That is, since the liquid crystal material smoothly flows on the surface of the substrate whose hydrophilicity is improved by such surface treatment, the amount of unnecessary liquid crystal material remaining as a residue on the outer surface of the cell without being filled inside the cell is further increased. As a result, the effective utilization rate of the liquid crystal material in the liquid crystal injection process can be improved to about 85%.

  The injection hole is preferably formed by removing a part of a sealing material for joining the pair of substrates at the peripheral portion thereof.

  Further, a guide means for guiding the liquid crystal material dropped on the base to the injection hole is formed on the electrode lead-out side so as to be separable by a sealing material or the like, and the liquid crystal material is formed along the guide means. When the is moved to the injection hole, the movement to the injection hole can be performed more smoothly.

  After filling the liquid crystal material into the gap, the injection hole is preferably closed with a sealing material, and this sealing material is preferably integrated with the sealing material.

  Note that the liquid crystal element is a guest-host type liquid crystal element in which negative liquid crystal molecules are used as a host material and dichroic dye molecules are used as a guest material, which improves light transmittance when no voltage is applied, It is desirable for improving the contrast with the application.

  Moreover, since the said light modulation apparatus is distribute | arranged in the optical path of an imaging system, the imaging device of this invention becomes an imaging device which can utilize the characteristic of the said light modulation apparatus mentioned above effectively.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  1 to 11 show a light control device using a guest-host type liquid crystal (GH) cell according to the present embodiment and a manufacturing method thereof, and FIGS. 12 to 13 show an image pickup device equipped with the light control device. It is shown.

  1A is a plan view of the GH cell 52, FIG. 1B is an enlarged cross-sectional view of a portion along the line IB-IB in FIG. 1A, and FIG. 1C is an IC in FIG. 1A. FIG. 2 is an enlarged sectional view taken along line II-II in FIG. 1A, FIG. 3A is a plan view of the lower substrate of the GH cell, and FIG. It is a top view of a board | substrate.

  As in the example shown in FIG. 18, the GH cell 52 includes a lower substrate (first substrate) 31 a made of glass or the like having a thickness of 200 to 500 μm facing each other, and a thickness 200 smaller than this. And an upper substrate (second substrate) 31b made of glass or the like of ˜500 μm. Each of these substrates is formed with an ITO (Indium Tin Oxide) electrode (transparent electrodes 32a and 32b) and a liquid crystal alignment film 33a and 33b with a thickness of 30 to 100 nm. The liquid crystal alignment films 33a and 33b are subjected to a liquid crystal alignment process by a rubbing method, etc. On the lower substrate 31a, the drawn portions 32c and 32e of the transparent electrodes 32a and 32b in a portion 31c larger than the upper substrate 31b. Are provided.

  The substrates 31a and 31b are aligned and overlapped in a state of facing each other on the electrodes 32a and 32b side, and the peripheral portion is sealed in a main sealing material (sealing material) 35 into an empty cell configured. The GH liquid crystal material 34 is injected from an injection hole 57 formed on the electrode lead-out portion side of the lower substrate 31 a, and the injection hole 57 is sealed with an end seal material (sealing material) 51.

For example, a sealing material (mainly made of a thermosetting epoxy resin containing a glass fiber having a diameter of 3 μm, for example, on the cell periphery of one substrate (for example, for the lower substrate 31a) formed with the transparent electrode 32a and the liquid crystal alignment film 33a (Seal) 55 is applied with a predetermined width. Then, on the other substrate (for example, for the upper substrate 31b) on which the transparent electrode 32b and the liquid crystal alignment film 33b are formed, a plastic ball having a diameter of 3 μm, for example, is uniformly dispersed as a spacer 36 by wet spraying or dry spraying, and the two substrates After being aligned and stacked, the peripheral portion of the sealing material 55 is cured by heat treatment while applying pressure under appropriate conditions (for example, 150 to 170 ° C., 1 to ² kg / cm ² ) using a hot press plate. Then, the bonding of both substrates is completed. Then, the bonded substrate is separated into a set of 31a and 31b, thereby producing an empty cell.

  The ITO electrode 32b extending outside the effective optical path 20 of the upper substrate 31b is electrically connected to the electrode lead portion 32e provided on the lower substrate 31a. Specifically, the ITO electrode 32b of the upper substrate 31b and the electrode lead portion 32e of the lower substrate 31a are connected to each other by a conductive material 26 such as a carbon paste on the outside of the sealing material 55, and the GH cell 52 Outside the effective optical path 20, conduction between substrates, that is, extraction of the transparent electrode 32 b can be performed.

  The light control device 53 according to the present embodiment includes a GH cell 52 and a polarizing plate 11 as shown in FIG. 11, and in the GH cell 52, as described above, the transparent electrodes 32a and 32b and the liquid crystal alignment. A mixture 34 of negative liquid crystal molecules (host material) and positive dichroic dye molecules (guest material) is enclosed between two glass substrates 31a and 31b on which the films 33a and 33b are formed. (See FIG. 16).

  As the liquid crystal molecule, for example, MCL-6608 manufactured by Merck, which is a negative type liquid crystal having a negative dielectric anisotropy, is used as an example, and the dichroic dye molecule has anisotropy in light absorption. For example, D5 manufactured by BDH, which is a positive dye that absorbs light in the molecular long axis direction, is used as an example. The light absorption axis of the polarizing plate 11 is orthogonal to the light absorption axis when a voltage is applied to the GH cell 52.

  The light control device 53 is disposed between a lens front group 15 and a lens rear group 16 each composed of a plurality of lenses such as a zoom lens. The light transmitted through the lens front group 15 is linearly polarized through the polarizing plate 11 and then enters the GH cell 52. The light transmitted through the GH cell 52 is collected by the rear lens group 16 and displayed on the imaging surface 17 as an image.

  And the polarizing plate 11 which comprises this light control apparatus 53 can be taken in / out with respect to the effective optical path 20 of the light which injects into the GH cell 52 as proposed also in the prior application invention. Specifically, the polarizing plate 11 can be moved out of the effective optical path 20 by moving it to a position indicated by a virtual line. As means for taking in and out the polarizing plate 11, a mechanical iris as shown in FIG. 12 may be used.

  This mechanical iris is a mechanical diaphragm device that is generally used for a digital still camera, a video camera, and the like, and mainly includes two iris blades 18 and 19 and a polarizing plate 11 attached to the iris blade 18. The iris blades 18 and 19 can be moved in the vertical direction. The iris blades 18 and 19 are relatively moved in the direction indicated by the arrow 21 using a drive motor (not shown).

  As a result, as shown in FIG. 12, the iris blades 18 and 19 are partially overlapped. When the overlap increases, the opening 22 on the effective optical path 20 located near the center of the iris blades 18 and 19 is polarized. Covered by a plate 11.

  12A to 12C are partial enlarged views of the mechanical iris in the vicinity of the effective optical path 20. At the same time that the iris blade 18 moves downward, the iris blade 19 moves upward. Along with this, as shown in FIG. 12A, the polarizing plate 11 attached to the iris blade 18 also moves out of the effective optical path 20. Conversely, the iris blades 18 and 19 overlap each other by moving the iris blade 18 upward and the iris blade 19 downward. Accordingly, as shown in FIG. 12B, the polarizing plate 11 moves on the effective optical path 20 and gradually covers the opening 22. When the overlapping of the iris blades 18 and 19 increases, the polarizing plate 11 covers the entire opening 20 as shown in FIG.

  Next, the dimming operation of the dimming device 53 using this mechanical iris will be described.

  As the subject (not shown) becomes brighter, as shown in FIG. 12 (a), the iris blades 18 and 19 opened in the vertical direction are driven by a motor (not shown) and start to overlap. Accordingly, the polarizing plate 11 attached to the iris blade 18 starts to enter the effective optical path 20 and covers a part of the opening 22 (FIG. 12B).

  At this time, the GH cell 52 does not absorb light (note that there is a slight attenuation of incident light by the GH cell 52 due to thermal fluctuation or surface reflection). For this reason, the light having passed through the polarizing plate 11 and the light having passed through the opening 22 have substantially the same intensity distribution.

  Thereafter, the polarizing plate 11 completely covers the opening 22 (FIG. 12C). Furthermore, when the brightness of the subject increases, the voltage applied to the GH cell 52 is increased, and light adjustment is performed by absorbing light in the GH cell 52.

  On the other hand, when the subject becomes dark, first, the voltage applied to the GH cell 52 is decreased or not applied, thereby reducing the light absorption effect of the GH cell 52 or not. And When the subject becomes darker, the iris blade 18 is moved downward and the iris blade 19 is moved upward by being driven by a motor (not shown). Thus, the polarizing plate 11 is moved out of the effective optical path 20 (FIG. 12A).

  According to this method, as shown in FIG. 11 and FIG. 12, when it is desired to increase the transmittance, the polarizing plate 11 (light transmittance, for example, 40% to 50%) is taken out from the effective optical path 20 of light. Therefore, the amount of incident light by the polarizing plate 11 is not reduced. Therefore, when the light control device 53 is compared with a conventional light control device in which the polarizing plate is always placed in the effective light path 20, the maximum light transmittance is improved by about twice, for example. The minimum light transmittance is the same for both.

  Moreover, since the polarizing plate 11 is put in and out using a mechanical iris that has been put to practical use in a digital still camera or the like, the light control device can be easily implemented. Moreover, since the GH cell 52 is used, in addition to the light control by the polarizing plate 11, the light control can be performed by the GH cell 52 effectively controlling the light transmittance.

  In this way, the light control device 53 can increase the contrast ratio between light and dark and can keep the light amount distribution substantially uniform. In addition, as shown in FIG. 17, the liquid crystal material 34 includes a negative liquid crystal having a negative dielectric anisotropy (Δε), and a positive dichroic dye molecule having a positive light absorption anisotropy (ΔA). Therefore, the average light transmittance of visible light decreases from about 78% to about 10% as the pulse voltage increases, and the change in light transmittance is relatively steep. In particular, the light transmittance at the time of transparency is improved and the contrast is improved, and a compact light control device that can be used by incorporating the GH cell in the imaging optical system can be realized.

  Next, a method for manufacturing the GH cell 52 constituting the above-described light control device 53 will be described with reference to FIGS.

First, as shown in FIG. 4A, one glass substrate (for lower substrate) in which a transparent electrode 32a made of ITO or the like and a liquid crystal alignment film (not shown here) made of polyimide or the like are formed in a predetermined pattern, respectively. A main sealing material (sealing material) 55 made of a thermosetting epoxy resin containing, for example, a glass fiber having a diameter of 3 μm, for example, is applied to a peripheral portion of the transparent electrode 32b made of ITO or the like and polyimide. A plastic ball having a diameter of 3 μm, for example, is uniformly sprayed by wet spraying or dry spraying on the other glass substrate (for the upper substrate) formed with a liquid crystal alignment film (not shown here) having a predetermined pattern. Then, these two glass substrates are aligned and overlapped, and then heat-treated while applying pressure under appropriate conditions (for example, 150 to 170 ° C. and 1 to ² kg / cm ² ) with a hot press plate. The peripheral sealing material 55 is cured, and the bonding of both glass substrates is completed. Then, the bonded substrate is separated into a set of 31a and 31b, thereby producing an empty cell.

  At this time, a liquid crystal injection hole 57 in which a part of the main seal material 55 is removed is formed on the side of the enlarged portion 31c provided with the electrode lead portions 32c and 32e of the lower substrate 31a. That is, in the prior art, the liquid crystal injection hole 7 is provided near the center of one side of the empty cell formed by bonding the glass substrates as shown in FIGS. 18 to 20, whereas the liquid crystal injection hole 57 is provided in the electrode lead portion 32c32e. Provided on the side. A conductive material 26 made of carbon paste is applied between the upper and lower substrates, and the transparent electrode 32b of the upper substrate 31b is connected to the electrode lead portion 32e of the lower substrate 31a.

  Next, as shown in FIG. 4B, in this empty cell state, the surface of the glass substrate 31a in the vicinity of the liquid crystal injection hole 57 is subjected to ultraviolet irradiation (UV ozone cleaning) treatment, plasma treatment, or laser light. It is desirable to perform irradiation treatment. Thereby, on the surface of the lower substrate 31a, the organic compound as a main contamination source is decomposed and / or the contaminant particles are physically removed to clean the substrate surface.

  Among these surface treatments, the ultraviolet irradiation (UV ozone cleaning) treatment is performed by irradiating excimer light (about 60 seconds) from an excimer lamp (dielectric barrier discharge lamp) using, for example, the apparatus shown in FIG. The organic compound contaminating the substrate surface is decomposed and removed by the strong oxidizing power generated by the synergistic effect of the UV light (172 nm line) and the ozone generated thereby, and the substrate surface is cleaned.

Further, as the plasma processing, for example, by using a parallel plate RF plasma apparatus shown in FIG. 9 and performing processing for about 30 seconds under the conditions of Ar = 25 sccm, pressure 1 Pa, RF applied power 300 W (13.56 MHz), Ar ^By the sputtering action of ⁺ ions, contaminants (not only organic substances but also inorganic substances) on the substrate surface are physically removed, and the substrate surface is cleaned.

  Further, as the laser light irradiation treatment, for example, the substrate surface is cleaned under the following conditions by setting in an excimer laser light irradiation device having a gas jet nozzle shown in FIG. That is, contaminants on the surface of the substrate are exposed to the pulse laser beam and float from the surface of the substrate, and jet gas is blown there, and is desorbed and removed from the surface of the substrate by the suction nozzle.

Laser source: KrF excimer laser (wavelength 248 nm)
Energy density: 400 mJ / cm ²
Number of shots: 30 shots (30 Hz)
Scan speed: 50 mm / s
Jet gas: N ₂ 20 l / s

  Next, as shown in FIG. 4C, a pair of guides 60 for guiding the liquid crystal injection is formed on the surface of the lower substrate 31a so as to be connected to the main seal material 55 in the vicinity of the injection hole 57. . The guide 60 may be made of a seal material. Examples of usable seal materials include acrylic UV curable resins used for end sealing for sealing (for example, Photolek A-704 manufactured by Sekisui Fine Chemical Co., Ltd.). Such a high-viscosity type) can be preferably used.

  Next, as shown in FIG. 5 (d), using a precision dispenser (for example, SMP-III type manufactured by Musashi Engineering Co., Ltd.), the liquid crystal material 34 is removed in an amount suitable for the size and cell gap of the empty cell (that is, empty cell). In the vicinity of the injection hole 57, it is dropped on the surface of the lower substrate 31a between the pair of guides 60 by an amount equal to (area × volume corresponding to cell gap) or slightly larger than that.

  In this state, as shown in FIG. 4 (e), when the atmosphere around the empty cell is evacuated and a predetermined vacuum degree is reached (approximately 0.1 Torr or less), the empty cell is inclined (for example, about The liquid crystal material 34 previously dropped is slid on the surface of the lower substrate 31 a toward the injection hole 57 and moved to the injection hole 57, and the entire injection hole 57 is moved to the liquid crystal material 34. Completely block with.

  At this time, since the hydrophilicity of the surface of the lower substrate 31a is improved by the surface treatment described above, the liquid crystal material 34 flows smoothly toward the injection hole 57 while being guided by the guide 60 on the surface of the lower substrate 31a. To do.

  Next, as shown in FIG. 4F, evacuation around the cell is stopped, and the atmosphere around the cell is gradually returned to atmospheric pressure by a nitrogen vent. As a result, a pressure difference is generated between the inside of the cell and the outside of the cell, and the liquid crystal material 34 staying in the injection hole 54 begins to penetrate into the cell gap, and finally the entire inside of the cell is filled with the liquid crystal material 34.

  Next, as shown in FIG. 6G, after the guide 60 is removed, the injection hole 57 is sealed with an end seal material 51, and heat treatment (nematic isotropic phase transition) is performed to stabilize the liquid crystal alignment state. (At a temperature slightly above the temperature), the fabrication of the GH cell 52 is completed.

  When performing the liquid crystal injection process in each of the above steps, as shown in FIG. 7, using the work tray 61 that can set several tens of empty cells, for example, the dropping step of FIG. It is preferable to perform batch processing for each process at the same time because high working efficiency can be obtained.

  According to the present embodiment, as shown in FIG. 5 (d), the injection hole 57 is provided on the electrode lead-out portion side of the lower substrate 31a, and the substrate surface in the vicinity is desirably subjected to a hydrophilic treatment, and then the GH liquid crystal material. As shown in FIG. 5 (e), an appropriate amount is dropped, and this is made to flow to the injection hole 47 to close the injection hole 57. Then, as shown in FIG. Since the liquid crystal material 34 is filled in the cell using the pressure difference, an appropriate amount of the liquid crystal material 34 can always be easily injected and filled without waste. Therefore, there was almost no extra liquid crystal material that was inevitably generated when manufactured by a conventional liquid crystal injection process and remained as a residue on the cell surface without being filled inside the cell and filling the inside of the cell, Since it is possible to manufacture with the minimum required amount of material, the effective utilization rate of the liquid crystal material at the time of liquid crystal injection is from about 50% to about 75%, and further to 85% (the substrate surface is hydrophilized). Case) can be greatly improved.

  As a result, even if an expensive guest-host type liquid crystal material is used, its manufacturing cost does not increase, and it is not necessary to add a dedicated cell cleaning step after the liquid crystal material is injected.

  In this way, a rectangular wave is input as a driving waveform to the GH cell 52 manufactured by the liquid crystal injection process with a high material effective utilization rate, and a change in light transmittance when an operating voltage is applied is measured as shown in FIG. As shown in FIG. 17, the average light transmittance of visible light (in the air) decreased from the maximum transmittance of about 80% to several percent as the operating voltage was applied. Although it depends on the liquid crystal cell structure and the constituent materials used, the GH cell 52 reached almost the minimum transmittance when a pulse voltage of ± 5 V (1 kHz) or higher was applied.

  In addition, the transient response time of the light transmittance when the drive pulse is changed is shortened, and a high-speed operation of 20 ms or less is possible. This could be realized both when the drive waveform was subjected to pulse voltage modulation and pulse width modulation.

  As a result, it has become possible to manufacture a liquid crystal light control device that ensures a sufficient optical density ratio and operates at a high speed in a transient response with greatly reduced manufacturing costs.

  FIG. 13 shows an example in which the light control device 53 having the GH cell 52 according to the present embodiment is incorporated in a CCD (Charge Coupled Device) camera.

  That is, in the CCD camera 70, along the optical axis indicated by the alternate long and short dash line, the first group lens 71 and the second group lens (for zooming) 72 corresponding to the lens front group 15 and the third group lens corresponding to the lens rear group 16. 73, a fourth group lens (for focusing) 74, and a CCD package 75 are arranged in this order at an appropriate interval. The CCD package 75 includes an infrared cut filter 75a, an optical low-pass filter system 75b, and a CCD image sensor 75c. Is stored.

  Between the second group lens 72 and the third group lens 73, a dimming device 53 composed of the GH cell 52 and the polarizing plate 11 is disposed on the same optical path for adjusting the amount of light (aperture stop). Installed on. The focusing fourth group lens 74 is arranged so as to be movable between the third group lens 73 and the CCD package 75 along the optical path by a linear motor 77, and the zoom second group lens 72 is arranged in the optical path. Along the first group lens 71 and the light control device 53, the first group lens 71 and the light control device 53 are movable.

  The embodiment described above can be variously modified based on the technical idea of the present invention, and the cell structure, its layout, materials used, liquid crystal cell driving method, light control device configuration, etc. It can be selected or changed as appropriate without departing from the spirit of the present invention.

  For example, in the above-described example, the position of the injection hole in the liquid crystal injection process, the method of dropping the liquid crystal material, the method of flowing the dropped liquid crystal material into the injection hole, and the like may be various. Other methods of placing the liquid crystal material on the substrate without dropping may be applied. Furthermore, the substrate surface treatment for improving the fluidity may be a combination of a plurality of the above-described various treatments. Alternatively, it may not be necessary to perform such surface treatment. Further, the above-described guide 60 can be used as it is as an end seal material without being removed. Such a guide 60 may not be provided.

Further, it is preferable to use a negative type liquid crystal for the GH cell, but a positive type liquid crystal may be used, and the dichroic dye is not limited to the positive type, and may be a negative type. Pulse voltage modulation (PHM) may be used as a driving method of the liquid crystal cell, but it can also be applied to driving by pulse width modulation (PWM).

  The light control device of the present invention is widely used for adjusting the light quantity of various optical systems such as a CMOS image sensor, an electrophotographic copying machine, and an optical communication device in addition to the optical diaphragm of the above-described imaging device such as a CCD camera. Applicable.

  Furthermore, the light control device of the present invention can be applied to various image display elements that display characters and images in addition to the optical filter.

FIG. 2A is a plan view of a GH cell according to an embodiment of the present invention, FIG. 3B is an enlarged cross-sectional view along the IB-IB line, and FIG. 2C is an enlarged cross-sectional view along the IC-IC line. It is an expanded sectional view which follows the II-II line of FIG. 1 (A). FIG. 6 is a plan view (A) of the lower substrate of the GH cell and a plan view (B) of the upper substrate. FIG. 4A is a plan view (a), (b), and (c) of each process stage showing the manufacturing method of the GH cell in the order of processes. FIG. 4D is a plan view (d), (e), and (f) of each process stage showing the manufacturing method of the GH cell in the order of processes. FIG. 4C is a plan view (g) of a final process stage of manufacturing the GH cell. It is the schematic explaining the state which performs the liquid crystal injection process of GH cell by batch processing similarly. It is the schematic which shows an example of the apparatus used for performing the surface treatment of an empty cell in the liquid crystal injection process of a GH cell. It is the schematic which shows the other example of the apparatus used for performing the surface treatment of an empty cell in the liquid crystal injection process of a GH cell. It is the schematic which shows the further another example of the apparatus used for performing the surface treatment of an empty cell in the liquid crystal injection process of GH cell. It is a schematic side view of the imaging device using the light control apparatus which consists of GH cells. It is the front view of the mechanical iris which attached the polarizing plate, and the elements on larger scale (a)-(c) which show the light control operation | movement in the vicinity of the effective optical path. It is a schematic sectional drawing of the camera system incorporating a light control device. It is the schematic which shows the principle of operation of the light modulation apparatus which consists of the conventional GH cell. It is a graph which shows the relationship between the light transmittance in a GH cell, and an applied voltage similarly. It is the schematic which shows the operation | movement principle of the light modulation apparatus using the GH cell based on prior invention. It is a graph which shows the relationship between the light transmittance in a GH cell, and an applied voltage similarly. FIG. 6 is a plan view (A) of the GH cell and an enlarged cross-sectional view (B) along the line XVIIIB-XVIIIB. FIG. 19 is an enlarged sectional view taken along the line XIX-XIX in FIG. FIG. 6 is a plan view (A) of the lower substrate of the GH cell and a plan view (B) of the upper substrate. It is the schematic explaining the liquid crystal injection process (dip system) of a GH cell similarly. It is the schematic explaining the liquid crystal injection process (touch system) of a GH cell.

Explanation of symbols

31a, 31b ... transparent substrate such as glass substrate, 31c ... enlarged portion,
13B ... negative liquid crystal molecules, 14 ... positive dichroic dye molecules, 5 ... incident light,
32a, 32b ... transparent electrode, 33a, 33b ... liquid crystal alignment film, 36 ... spacer,
11: Polarizing plate, 12A: GH liquid crystal cell of positive liquid crystal molecule,
12B: Negative liquid crystal molecule GH liquid crystal cell, 13A: Positive liquid crystal molecule, 15: Lens front group,
16 ... rear lens group, 17 ... imaging surface, 18, 19 ... iris blade,
20 ... Effective optical path (cell central part), 26 ... Conductive material, 32c, 32e ... Electrode lead-out part,
34 ... GH liquid crystal material, 51 ... End seal material (sealing material), 52 ... GH cell,
53 ... Light control device, 55 ... Main seal material (sealing material), 57 ... Injection hole, 60 ... Guide,
70 ... CCD camera, 71 ... 1 group lens, 72 ... 2 group lens (for zoom),
73 ... 3 group lens, 74 ... 4 group lens (for focusing), 75 ... CCD package,
75a ... Infrared cut filter, 75b ... Optical low pass filter (LPF),
75c ... CCD image sensor, 77 ... linear motor

Claims (14)

In a method of manufacturing a light control device comprising a liquid crystal element in which a pair of substrates each having an electrode are arranged opposite to each other on the electrode side, and a liquid crystal material is sealed in a gap between the pair of substrates.
A step of placing a predetermined amount of liquid crystal material in the vicinity of the injection hole in a state where the liquid crystal material is not sealed, and further closing the injection hole with the liquid crystal material;
And a step of filling the liquid crystal material into the gap from the injection hole.   The injection hole is formed on the side of the electrode lead portion provided on at least one of the pair of bases, and an appropriate amount of the liquid crystal material is dropped on the base in the vicinity of the injection hole, and the liquid crystal material is reduced in atmosphere. Is moved on the base to close the injection hole with the liquid crystal material, and then the reduced pressure state of the atmosphere is relaxed, and the liquid crystal material is removed from the injection hole by the pressure difference between the inside and the outside between the pair of bases. The method for manufacturing a light control device according to claim 1, wherein the gap is filled.   The surface of the substrate is subjected to at least one of ultraviolet irradiation treatment, plasma treatment, and laser light irradiation treatment on the electrode lead-out side, and the liquid crystal material is dropped on the substrate after the surface treatment. Item 3. A method for manufacturing a light control device according to Item 2.   3. The method for manufacturing a light control device according to claim 2, wherein the injection hole is formed by removing a part of a sealing material for joining the pair of bases at a peripheral portion thereof.   A guide means for guiding the liquid crystal material dropped on the substrate to the injection hole is formed on the electrode lead portion side, and the liquid crystal material is moved to the injection hole along the guide means. Item 3. A method for manufacturing a light control device according to Item 2.   The method for manufacturing a light control device according to claim 1, wherein after filling the liquid crystal material into the gap, the injection hole is closed with a sealing material.   2. The method for manufacturing a light control device according to claim 1, wherein the liquid crystal element is a guest-host liquid crystal element having negative liquid crystal molecules as a host material and dichroic dye molecules as a guest material. In a light control device comprising a liquid crystal element in which a pair of bases each having an electrode are arranged opposite to each other on the electrode side, and a liquid crystal material is sealed in a gap between the pair of bases,
One of the pair of bases has a portion enlarged than the other, an injection hole for the liquid crystal material is formed on the enlarged side, and the injection hole is sealed. A light control device.   The light control device according to claim 8, wherein the injection hole is formed on a side of an electrode lead portion provided on at least one of the pair of bases.   The light control device according to claim 9, wherein at least one kind of treatment among ultraviolet irradiation, plasma irradiation, and laser light irradiation is performed on the surface of the substrate on the electrode lead-out side.   The light control device according to claim 9, wherein the injection hole is formed by removing a part of a sealing material for joining the pair of substrates at a peripheral portion thereof.   The light control device according to claim 8, wherein the injection hole is blocked by a sealing material.   The light control device according to claim 8, wherein the liquid crystal element is a guest-host type liquid crystal element having a negative liquid crystal molecule as a host material and a dichroic dye molecule as a guest material.   An imaging device, wherein the light control device according to claim 8 is arranged in an optical path of an imaging system.

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