JP2017010060A - Imaging apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus employing a porous body having high strength, low reflection, and excellent dust proof property.SOLUTION: An imaging apparatus for imaging a subject image from a lens on an imaging element through an optical filter has a porous body having pores which derive from spinodal type phase separation and which three-dimensionally communicate with each other at least on a side opposite to the imaging element of the optical filter.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus and an image forming apparatus using a porous body that suppresses adhesion of foreign matters such as dust.

  In an imaging device such as a digital camera, a photographic light beam is received by an imaging device such as a CCD or C-MOS, and a photoelectric conversion signal output from the imaging device is converted into image data and recorded on a recording medium such as a memory card. To do.

  In such an imaging apparatus, a low-pass filter and an infrared cut filter are arranged on the subject side of the imaging element. In particular, in a single-lens reflex digital camera with interchangeable lenses, a mechanical operation unit such as a shutter is disposed in the vicinity of an optical filter such as a low-pass filter, and foreign matter such as dust generated from these operation units is transferred to the low-pass filter or the like. May adhere. Further, when the lens is exchanged, dust or the like may enter the camera body from the opening of the lens mount and adhere to it. When dust adheres to an optical filter such as a low-pass filter, the attached portion becomes a black dot and appears in the photographed image, which may deteriorate the quality of the photographed image.

  As a conventional technique for solving this problem, Patent Document 1 discloses a technique for removing dust by providing a dust-proof film on a subject side of an image sensor and vibrating the film with a piezoelectric element. Patent Document 2 discloses a technique for applying a coat to the surface to make it difficult for dust and the like to adhere.

  Further, in an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, an electrostatic latent image is formed by exposing a photoconductor to a laser beam. The electrostatic latent image is developed with toner, the obtained toner image is transferred onto a sheet-like recording medium, and then the toner is heated and fixed by a fixing device to form an image on the recording medium.

  In such an image forming apparatus, a light source that emits laser light based on image information, a rotating polygon mirror that deflects and scans the laser light emitted from the light source, and laser light that is polarized and scanned by the rotating polygon mirror on the photoreceptor. An fθ lens for forming an image, a reflection mirror, and the like are included in the housing. And it has the optical apparatus which inject | emits a laser beam to a photoreceptor from the opening part in a housing. When dirt is generated on the laser optical path, image omission may occur in a portion corresponding to the dirt on the image, which may deteriorate the image quality. For this reason, sealing the housing prevents intrusion of dust, toner, etc., and attaches a transparent dustproof glass to the opening of the housing that emits laser light, and prevents the dirt of the dustproof glass by providing a shutter there. An apparatus has been proposed (Patent Document 3).

JP 2002-204379 A JP 2006-163275 A JP-A-11-167080

  The above-mentioned Patent Document 1 is a method of removing foreign matter by vibrating a dustproof curtain. To remove foreign matter attached to a dustproof film, a large amount of energy is required and the structure is complicated.

  In the method described in Patent Document 2 in which a surface is coated to make it difficult for dust and the like to adhere thereto, an optical film must be formed in multiple layers as an antireflection film in order to maintain optical performance.

  The method of providing a shutter in Patent Document 3 is easily scratched and the structure is complicated.

  In addition, none of the conventional techniques can perform satisfactory dust removal, and further reduction of dust is required.

  The present invention has been made in view of such background art, and provides an imaging apparatus and an image forming apparatus using a porous body having high strength, low reflection, and excellent dust resistance. It is.

  In order to solve the above problems, an imaging apparatus according to the present invention is an imaging apparatus for forming a subject image from a lens on an imaging element through an optical filter, and at least the imaging filter and the imaging element. Has a porous body on the opposite side, and the porous body has pores communicating with each other three-dimensionally derived from spinodal phase separation.

  The image forming apparatus of the present invention is an image forming apparatus having an optical device used for irradiating light to form an image, wherein the dustproof glass provided in the optical device is a tertiary derived from spinodal phase separation. It has the porous body which has the hole which originally communicated with each other.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device and image forming apparatus using the porous body which is high intensity | strength, and is excellent also in low reflection and dustproofness can be provided.

1A and 1B illustrate an imaging device of the present invention. The electron microscope observation figure explaining the porous body of this invention. Graph showing dustproof effect. The figure explaining liquid bridge | crosslinking. The figure explaining a hole diameter and frame | skeleton diameter. The figure explaining the optical member of this invention. 1 is a diagram illustrating an example of a foreign matter removing device provided in an imaging apparatus of the present invention. The figure which shows an example of a piezoelectric element. The figure which shows an example of the vibration principle of the piezoelectric element of this invention. FIG. 3 is a schematic diagram illustrating a vibration principle of a foreign matter removing apparatus provided in the imaging apparatus of the present invention. 1A and 1B illustrate an image forming apparatus of the present invention. The figure explaining a porosity.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. However, the scope of the invention is not limited.

(First embodiment)
As a first embodiment of the present invention, an imaging device using a porous body, specifically, an imaging device for forming a subject image from a lens on an imaging device through an optical filter will be described. FIG. 1 is a diagram illustrating an embodiment of an imaging apparatus of the present invention. In FIG. 1, reference numeral 6 denotes an imaging device, and reference numeral 31 denotes a lens that can be detached from the imaging device 6. In an imaging apparatus such as a digital single-lens reflex camera, photographing screens having various angles of view can be obtained by replacing a photographing lens used for photographing with a lens having a different focal length. Reference numeral 4 denotes an image sensor. 5 is a porous body, 32 is a low-pass filter, and 33 is an infrared cut filter. The image sensor 4 is housed in a package (not shown), and this package holds the image sensor in a sealed state with a cover glass (not shown). Then, in the optical path from the imaging optical system in the removable lens 31 to the imaging device 6, the imaging optical system is cut so that a spatial frequency component higher than necessary of the object image is not transmitted onto the imaging device 4. A low pass filter 32 for limiting the off frequency is provided. An infrared cut filter 33 is also formed. Between the optical filter such as a low-pass filter or an infrared cut filter and the cover glass, a sealing structure such as a double-sided tape is used (not shown). This prevents dust generated outside or inside the imaging apparatus from entering between the optical filter and the cover glass. In the present embodiment, an example in which both the low-pass filter and the infrared cut filter are provided as the optical filter is described, but either one of the low-pass filter and the infrared cut filter may be used. The porous body may be integrally formed as a film on the substrate. The base material may be a low-pass filter 32 made of quartz, or may be quartz glass, Corning 7059 glass, Nippon Electric Glass Neoceram N-0, or other heat resistant glass. The heat-resistant glass refers to a substrate that can withstand the process of forming a porous body, and thermal expansion matching with the porous body or adjustment of the film thickness may be performed. The porous body 5 is disposed at least on the side of the optical filter opposite to the imaging element 4. In other words, the optical filter is disposed on the side close to the removable lens 31. That is, it is arranged in an environment in the vicinity of the detachable lens mounting portion. In this environment, mechanical operating parts such as shutters are arranged in the vicinity, and foreign matters such as dust generated from these operating parts may adhere to the low-pass filter or the like. Further, when the lens is exchanged, dust or the like may enter the camera body from the opening of the lens mount and adhere to it. In this way, dust, dust, dirt, etc. are likely to enter, and it is easy to come into contact with foreign objects and be easily damaged. Of course, the porous body can be disposed in any location in the imaging apparatus where dust is easily attached. It is also possible to provide a foreign substance removing device for removing foreign substances by applying vibration or the like to the porous body.

  Next, the porous body of the present invention will be described. FIG. 2 is an electron microscopic observation view of the surface of the porous body. In FIG. 2, reference numeral 1 denotes a hole, and a hole is formed that is bent in the horizontal direction on the paper surface toward the inside of the glass (in the vertical direction on the paper surface). Reference numeral 2 denotes a skeleton that forms holes, and is made of, for example, silicon oxide. FIG. 2 is an electron microscopic view of the surface of the porous body, and similar pores and skeletons are formed inside the glass. In this specification, as shown in FIG. 2, the holes communicating in the horizontal direction on the paper toward the inside of the glass (in the vertical direction on the paper) are referred to as three-dimensionally communicating holes. Further, as shown in FIG. 2, the skeleton 2, that is, a spinodal structure connected in a three-dimensional manner (in a vertical direction and a horizontal direction on the paper surface) while being bent in a complicated manner. As will be described later, the spinodal structure is a porous structure derived from spinodal phase separation. The porous body of the present invention forms pores communicating with each other three-dimensionally by a skeleton that is bent and connected in a three-dimensionally complex manner. In other words, it has three-dimensionally continuous mesh holes. Such a porous body having a characteristic shape can be obtained, for example, by removing at least one kind of phase-separated glass phase-separated into at least two kinds of phases.

  It should be noted that the porous body of the present invention having three-dimensionally communicating with each other and having mesh-like pores has a skeleton (portion other than pores) not only in the film thickness direction but also in the direction perpendicular to the film thickness direction Since it exists densely, sufficient strength can be obtained. For example, it is conceivable that the foreign matter adhering to the porous body is removed by direct contact with a human (or machine), but even if it is removed using at least a cleaning member such as rubber or fiber, the surface structure changes. A strength that does not occur is sufficiently obtained.

  FIG. 3 shows the number of dust adhering to the surface after applying air pressure of 25 KPa and 50 KPa before measurement (initial stage) to silica glass having no pores on the surface and the porous body of the present invention. It is a graph of it. It can be seen that the porous body of the present invention has less dust from the beginning (before applying air pressure) to silica glass having no pores on the surface. There are several possible reasons why the porous body of the present invention has an excellent dustproof effect. Silica glass having no holes on the surface generates a force to suck dust, dirt, dirt, etc. over the entire glass surface. However, the porous body of the present invention generates a suction force only in the skeleton portion of the porous body. Therefore, it is considered that the suction force can be weakened. Further, the pores of the porous body of the present invention are entangled three-dimensionally toward the inside and communicate with each other, and are excellent in air permeability. This is also considered to have an effect of preventing the adsorption of dust, dirt, dirt, etc. to the surface. In addition, the porous body of the present invention exhibits an excellent dustproof effect by the action of weakening the adsorption force by liquid crosslinking.

  FIG. 4 schematically shows the adsorption force by liquid crosslinking. If there is a liquid 73 between the object 71 and the dust 72, a liquid bridge is formed between the object 71 and the dust 72, the pressure is different between the inside and the outside of the air interface of the liquid bridge, and the pressure on the liquid side is lower. When the pressure on the gas side is equal to the atmospheric pressure, the pressure on the liquid side is a negative pressure lower than the atmospheric pressure. This negative pressure is known to be expressed by the equation (1). Further, it is known that the suction force is represented by the formula (2), and is a value obtained by multiplying the negative pressure p by the area S. Here, R1 is the radius of curvature of the air interface of the liquid 73 formed between the object 71 and the dust 72, and R2 is the radius of the contact area between the object 71 and the liquid 73. S is represented by the product of the surface area S0 and the hole ratio α.

  FIG. 4A shows a case where the surface of the object 71 is a smooth surface, and R2 is the dust radius R. FIG. FIG. 4B shows a case where the object 81 is a porous body, in which case R2 is half R ′ of the skeleton diameter of the porous body.

  In order to reduce the suction force, R2 should be close to the value of R1, that is, the contact area between the object 71 (or 81) and the liquid 73 should be reduced. In FIG. 4B, R1 is determined by the unevenness of the contact portion and capillary condensation on the surface, but is considered to be close to about 10 nm. In the porous body of the present invention, R2 is defined not by the dust size 2R but by the skeleton diameter 2R ′, and the skeleton diameter 2R ′ is smaller than the dust size 2R. For this reason, since R2 becomes as small as R1, the absolute value of p becomes small as shown in the equation (1), and the suction force can be reduced. It can also be lowered by increasing the porosity.

  As described above, in order for the porous body of the present invention to maintain strength and obtain a dustproof effect, it is desirable that the average skeleton diameter on the surface of the porous body is 5 nm to 80 nm. More preferably, the average skeleton diameter is 5 nm or more and 50 nm or less. The average skeleton diameter in the present invention is defined as an average value of the minor axis in each approximated ellipse by approximating the skeleton on the surface of the porous body with a plurality of ellipses. Specifically, for example, as shown in FIG. 5B, the skeleton 2 is approximated by a plurality of ellipses 13 using an electron micrograph of the surface of the porous body, and the average value of the minor axis 14 in each ellipse is obtained. Can be obtained. Measure at least 30 points and find the average value. Note that the measurement need not be performed on the entire porous body, and may be performed in a desired region. When the average skeleton diameter is smaller than 5 nm, it becomes difficult to form, and when the average skeleton diameter is larger than 80 nm, the dustproof effect tends to be lowered. When the average skeleton diameter is 50 nm or less, a higher dustproof effect is exhibited.

  The average pore diameter on the surface of the porous body is preferably 5 nm or more and 500 nm or less, particularly 10 nm or more and 100 nm or less, and more preferably 15 nm or more and 80 nm or less. The average pore diameter in the present invention is defined as the average value of the minor axis in each approximated ellipse by approximating the pores on the surface of the porous body with a plurality of ellipses. Specifically, for example, as shown in FIG. 5A, an electron micrograph of the surface of the porous body is used to approximate the hole 1 with a plurality of ellipses 11, and the average value of the minor axis 12 in each ellipse is obtained. Can be obtained. Measure at least 30 points and find the average value.

  Further, considering the mechanical properties, it is desirable that the porosity of the porous body is usually 10% to 80%, particularly 20% to 75%. The porosity in this specification is defined as the ratio of pores when the surface area of the porous body is 1. Specifically, using an electron micrograph of the porous body surface made of a porous body as shown in FIG. 1, binarization processing is performed on the skeleton portion and the pore portion, and the ratio is obtained from the ratio. When the porosity is 80% or less, mechanical properties can be exhibited and a dustproof function is also exhibited.

  Among them, when the antireflection function is required, if the porosity is increased, reflection at the interface with air is reduced. In this case, the porosity is preferably 30% or more, more preferably 50% or more. Since the porous body of the present invention has a skeleton that is connected three-dimensionally in a complicated manner, the strength does not decrease even when the porosity is increased. Therefore, the refractive index can be lowered while maintaining the strength. In this way, it is possible to provide a porous body that has excellent antireflection performance and has a strength that is not damaged even if it touches the surface.

  The shape of the porous body is not particularly limited, and examples thereof include a plate-like porous body, a curved porous body, and a form in which the porous body is formed on a substrate. These shapes can be selected as appropriate. As the base material, a heat-resistant base material such as quartz glass, Corning 7059 glass, Nippon Electric Glass Neoceram N-0, sapphire, or quartz can be used. A form in which a porous body is directly formed on a low-pass filter made of quartz can also be suitably used. Since it has excellent antireflection performance, it is not necessary to provide a separate antireflection film, and it becomes possible to obtain an optical member having excellent optical performance of antireflection effect and dustproof effect on the surface.

  Next, a schematic configuration of the form in which the porous body is integrally formed on the substrate will be described below. This form is referred to herein as an optical member. In FIG. 6, the optical member 101 has a porous body 102 having holes that communicate with each other three-dimensionally described in the first embodiment on a base material 103. However, the present invention does not exclude an optical member made only of the porous body 102.

  Since the optical member 101 includes the porous body 102 having pores that communicate with each other three-dimensionally on the surface, the optical member 101 has surface characteristics that combine high surface strength and high porosity, and has high dustproof performance. Moreover, the optical member 101 can achieve higher strength by using the base material 103. Furthermore, since the porous body is formed on the base material, the thickness of the porous body can be controlled. If necessary, the porosity of the pores may change continuously or intermittently in the whole or a part of the porous body.

  Since this optical member has a clear boundary between the porous body and the base material, when used as an optical member, variations among samples are reduced, and high design accuracy can be realized. In addition, as will be described in detail later, a porous body having pores according to the purpose can be formed by arbitrarily changing the heat treatment conditions during production (heat treatment conditions for causing phase separation).

  This optical member has a spinodal structure skeleton, and the surface of the porous body and the substrate are continuously connected through continuous holes. Therefore, various application developments utilizing the characteristics of the base material and the spinodal structure are possible by using an arbitrary hole diameter and an arbitrary base material.

  The thickness of the porous body is not particularly limited, but is preferably 0.05 μm or more and 200.00 μm or less, more preferably 0.10 μm or more and 50.00 μm or less. If it is smaller than 0.05 μm, it tends to be difficult to form a spinodal structure, and if it is larger than 200.00 μm, the production cost may be high for forming a porous body.

  As the shape of the substrate, any shape of substrate can be used as long as a porous body can be formed. The base material may have a curvature.

  The softening temperature of the base material is preferably equal to or higher than a phase separation heating temperature that forms a spinodal structure of the porous body described later, and more preferably equal to or higher than a temperature obtained by adding 100 ° C. to the phase separation heating temperature. preferable. However, when the substrate is a crystal, the melting temperature is the softening temperature. When the softening temperature is lower than the temperature at which the spinodal structure of the porous body is formed, the base material is deformed during the heat treatment step of the phase separation, which is not preferable. In addition, the phase separation heating temperature which forms a spinodal structure represents the maximum temperature among the temperatures which form the said porous body (porous glass layer) of a spinodal structure.

  The substrate is preferably resistant to etching of the glass layer.

  The optical member can arbitrarily change the refractive index by controlling the porosity, and further can arbitrarily change the thickness of the porous body (porous glass layer).

  The imaging device of the present invention may include a foreign matter removing device as described above. FIGS. 7A and 7B are schematic views showing an example of the foreign matter removing device 470. FIG. The foreign matter removing device 470 includes a vibration member 410, a flexible printed circuit board 420 connected to the piezoelectric element 430, and a fixing member called a sealing member 450, and is installed on a support body 501 provided with an imaging element and the like. . The piezoelectric element 430 and the vibration member 410 are fixed to the plate surface of the vibration member 410 at the first electrode surface of the piezoelectric element 430 as shown in FIG. In addition, a flexible printed circuit board 420 is electrically connected to a part of the second electrode surface 437 of the piezoelectric element 430 so that an alternating voltage can be applied to the piezoelectric element 430 from a power source. Although details will be described later, the vibration member 410 is vibrated by applying the alternating voltage. When this foreign matter removing device 470 is provided in contact with the porous body of the present invention, the porous body of the present invention is difficult to adhere foreign matter such as dust, dust, dirt, etc. It is possible to efficiently remove the foreign matters by applying.

  FIG. 8 is a diagram illustrating an example of the piezoelectric element 430 included in the foreign matter removing apparatus. The piezoelectric element 430 includes a piezoelectric material 431, a first electrode 432, and a second electrode 433, and the first electrode 432 and the second electrode 433 are disposed to face the plate surface of the piezoelectric material 431. In the drawing, the surface on which the first electrode 432 that comes out in front of the piezoelectric element 430 on the right side (c) is placed is in front of the first electrode surface 436 and the piezoelectric element 430 on the left side (a) in the figure. A surface on which the second electrode 432 is provided is a second electrode surface 437. Here, the electrode surface in the present invention refers to the surface of the piezoelectric element on which the electrode is installed. For example, even if the first electrode 432 wraps around the second electrode surface 437 as shown in FIG. good. Furthermore, there may be a third electrode used for sensing or the like on the second electrode surface.

  The first electrode 432 and the second electrode 433 are each formed of a conductive layer having a thickness of about 5 nm to 5000 nm. The material is not particularly limited as long as it is usually used for piezoelectric elements. Examples thereof include metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, and Cu, and compounds thereof. The first electrode 432 and the second electrode 433 may be made of one of these, or may be made by laminating two or more of these. In addition, the first electrode 432 and the second electrode 433 may be made of different materials.

  FIG. 9 is a diagram illustrating an example of the operation principle of the piezoelectric element 430 included in the foreign matter removing apparatus. In the piezoelectric element 430, the piezoelectric material 431 is polarized in the direction perpendicular to the first electrode surface 436 in advance, so that a high frequency voltage can be applied from the power source to the first electrode 432 and the second electrode 433. Yes. The piezoelectric element 430 generates stretching vibration in the length direction of the piezoelectric element 430 due to stretching strain of the piezoelectric material 431 generated by an alternating electric field generated in the direction indicated by the arrow in the electric field direction 435. The magnitude of the stretching vibration in the length direction of the piezoelectric element is closely related to the magnitude of the piezoelectric displacement caused by the piezoelectric lateral effect of the piezoelectric ceramic. Reference numeral 434 represents the polarization direction.

  FIG. 10 is a schematic diagram showing an example of the vibration principle of the foreign matter removing apparatus 470 of the present invention. For convenience, only the piezoelectric element 430 and the vibration member 410 are shown in the figure. FIG. 10A shows a state in which an alternating voltage having the same phase is applied to the pair of left and right piezoelectric elements 430 to cause the vibration member 410 to generate a standing wave out-of-plane vibration. In the pair of left and right piezoelectric elements 430, the polarization of the piezoelectric material 431 is the same in the thickness direction of the piezoelectric element 430, and the foreign matter removing device 470 is driven in a seventh-order vibration mode. Here, the vibration mode of the present invention refers to the vibration member 410 for a standing wave having a plurality of nodes and abdomen that can be generated by out-of-plane vibration of the vibration member, and for a time when the nodes and abdomen are present. A traveling wave that moves in the length direction of.

  In FIG. 10B, an anti-phase alternating voltage having a phase opposite to 180 ° is applied to the pair of left and right piezoelectric elements 430 through the flexible printed circuit board 420 to generate a standing wave out-of-plane vibration on the vibration member 410. It represents the state that was made to. In the pair of left and right piezoelectric elements 430, the polarization of the piezoelectric material 431 is the same in the thickness direction of the piezoelectric element 430, and the foreign matter removing device 470 is driven in the sixth vibration mode. As described above, the foreign matter removing device 470 according to the present embodiment can more efficiently remove dust attached to the surface of the vibration member 410 by effectively using at least two vibration modes.

  However, the foreign substance removing device 470 that can be used in the present invention is not necessarily driven only in such a vibration mode. For example, one piezoelectric element 430 may be provided on the vibration member 410, and the pair of left and right piezoelectric elements 430 may not have the same polarization direction of the piezoelectric material 431 in the thickness direction of the piezoelectric element 430. . Furthermore, instead of the 6th and 7th vibration modes described above, another vibration mode such as an 18th and 19th vibration mode may be used, or three or more vibration modes may be used. In FIG. 10, the vibration principle is shown using the standing wave vibration mode. However, the vibration mode using the traveling wave instead of the standing wave may be used by controlling an arbitrary frequency and an arbitrary phase. . However, it is preferable to select a natural mode in which the resonance frequency of the out-of-plane vibration generated by the vibration member 410 is outside the audible range so that the foreign matter removing device 470 does not generate unpleasant sound.

  The foreign matter removing device 470 may be disposed at any position between the imaging element 4 of the imaging device shown in FIG. For example, the vibration member 410 may be provided in contact with the porous body 5, the vibration member 410 may be provided in contact with the low-pass filter 32, or the vibration member may be provided in the infrared cut filter 33. 410 may be provided so that it may contact. In particular, when provided in contact with the porous body 5, as described above, foreign substances can be more efficiently removed. Note that the vibration member 410 of the foreign matter removing device 470 may be integrally formed with an optical filter such as the porous body 5, the low-pass filter 32, and the infrared cut filter 33. Further, the vibration member 410 may be formed of the porous body 5 and may have functions such as the low-pass filter 32 and the infrared cut filter 33.

(Second embodiment)
Next, an image forming apparatus using the porous body described in the first embodiment, specifically, an image forming apparatus having an optical device used to form an image by irradiating light will be described.

  FIG. 11 shows an example of an image forming apparatus. In FIG. 11, reference numeral 21 denotes an optical device for irradiating a photosensitive drum with laser light based on image information sent from an image reading device or a personal computer. A developing device 22 forms a toner image on the photosensitive drum with toner frictionally charged on the photosensitive drum. Reference numeral 23 denotes an intermediate transfer belt for conveying the toner image on the photosensitive drum to a transfer sheet. Reference numeral 24 denotes a paper feed cassette for storing paper on which a toner image is formed. Reference numeral 25 denotes a fixing device that adsorbs the toner image transferred onto the sheet to the sheet by heat. Reference numeral 26 denotes a paper discharge tray on which the fixed transfer paper is stacked. A cleaner 27 cleans toner remaining on the photosensitive drum. A dust-proof glass 28 is disposed at the laser light irradiation port of the photosensitive drum so that toner and dust do not adhere to optical members such as mirrors and lenses that are components of the optical device.

  In the image formation, the optical device 21 irradiates the photosensitive drum with light emitted by laser based on the image information, thereby forming an image on the photosensitive drum charged by the charger. Thereafter, a toner image is formed on the photosensitive drum by attaching toner to the image in the developing unit 22. The toner image is transferred from the photosensitive drum to the intermediate transfer belt 23, and the toner image is transferred again to the paper conveyed from the paper feed cassette 24, whereby the image is formed on the paper. The image transferred onto the paper is fixed with toner by the fixing device 25 and is stacked on the paper discharge tray 26. The optical device 21 forms a light source that emits laser light on the basis of image information, a rotating polygon mirror that deflects and scans the laser light emitted from the light source, and forms laser light polarized and scanned by the rotating polygon mirror on the photoreceptor. An optical member such as an fθ lens and a reflection mirror is provided in the casing. A dust-proof glass 28 is provided at the irradiation port of the laser beam to the photosensitive drum of the housing so that dirt such as dust, dust and toner does not adhere to optical members such as mirrors and lenses constituting the optical device. If toner scattered from a developing device or the like accumulates in the dust-proof glass, image defects such as a drop in the amount of laser light or white spots may occur. Therefore, the dust-proof glass disposed in the image forming apparatus of the present invention uses, at least in part, the porous body described in the first embodiment. The porous body may be integrally formed as a film on the substrate. As the base material, a heat-resistant base material such as quartz glass, Corning 7059 glass, Nippon Electric Glass Neoceram N-0, sapphire, or quartz is preferably used.

  In order to be suitably used in an image forming apparatus, for the same reason as in the first embodiment, the average skeleton diameter on the surface of the porous body is 5 nm or more and 80 nm or less, and more preferably the skeleton diameter is 5 nm or more and 50 nm or less. Is desirable. The average pore diameter on the surface of the porous body is preferably 5 nm or more and 500 nm or less, particularly 10 nm or more and 100 nm or less, and more preferably 15 nm or more and 80 nm or less. Furthermore, it is desirable that the porosity of the porous body is usually from 10% to 80%, particularly from 20% to 75%.

  When the antireflection function is required, the reflection at the interface with the air is reduced by increasing the porosity. In this case, the porosity is preferably 30% or more, more preferably 50% or more.

  The porous body of the present invention has an excellent feature that it is difficult for dust, dirt, dirt and the like to adhere to it, but when a photosensitive drum is not required to be irradiated by attaching a shutter or the like, toner or the like can be used. A form that protects the dust-proof glass from dirt, dust, and dust can also be used. It is also possible to attach a cleaning mechanism for wiping off dirt. Since the porous body of the present invention has high strength, it can withstand the impact on the porous body by a shutter, a cleaning mechanism, and the like. In addition, the image forming apparatus according to the present embodiment may include the foreign matter removing apparatus described above.

(Production method)
Hereinafter, a production method for producing the porous body of the present invention will be described. First, a method for producing a member made only of a porous body will be described. The porous body of the present invention can be obtained, for example, by removing at least one type of phase-separated glass that has been phase-separated into at least two types of phases.

  Examples of the material of the phase-separable base glass include silicon oxide-boron oxide-alkali metal oxide and silicon oxide-phosphate-alkali metal oxide as the silicon oxide base glass. Among these, it is preferable to use borosilicate glass of silicon oxide-boron oxide-alkali metal oxide for the phase-separable base glass.

  The method for producing the phase-separable base glass can be produced by preparing the raw materials so as to have the above composition, heating and melting the raw materials including the supply sources of the respective components, and molding the raw materials as necessary. it can. The melting and heating temperature for heating and melting may be appropriately set depending on the raw material composition and the like, but it is usually preferably in the range of 1350 to 1450 ° C, particularly 1380 to 1430 ° C. In the present specification, heating for melting the raw material is referred to as melting heating.

  For example, sodium carbonate, boric acid and silicon dioxide may be uniformly mixed as the raw material, heated to 1350 to 1450 ° C. and melted. In this case, any raw material may be used as long as it contains components of alkali metal oxide, boron oxide and silicon oxide as described above.

  When the porous glass has a predetermined shape, after synthesizing the phase-separable base glass, it may be formed into various shapes such as a tube, a plate, and a sphere at a temperature of about 1000 to 1200 ° C. . For example, after melting the raw materials and synthesizing the base glass, it is possible to suitably employ a method of molding in a state where the temperature is lowered from the melting temperature and maintained at 1000 to 1200 ° C.

  In general, the base glass is phase-separated by heat-treating the phase-separable base glass. “Phase separation” means, for example, when a borosilicate glass of silicon oxide-boron oxide-alkali metal oxide is used for the base glass, a silicon oxide rich phase and an alkali metal oxide-boron oxide rich phase inside the glass. , Meaning to cause phase separation on the nm scale. The phase separation heating temperature for phase separation is 400 to 800 ° C., and the phase separation heating time is usually set within a range of several hours to 100 hours according to the pore diameter of the obtained porous glass. In the present specification, heating for phase separation of the base glass is referred to as phase separation heating.

  Thus, the acid-soluble component is eluted and removed by bringing the phase-separable glass obtained from the phase separation heating step into contact with the acid solution. As the acid solution, for example, an inorganic acid such as hydrochloric acid or nitric acid can be preferably used, and the acid solution can be suitably used usually in a form using water as a solvent. What is necessary is just to set the density | concentration of an acid solution suitably in the range of 0.1 to 2 mol / L (0.1 to 2 normal) normally. In the acid treatment step (etching treatment step) in contact with the acid solution, the temperature of the acid solution may be in the range of room temperature to 100 ° C., and the treatment time may be about 1 to 50 hours. Thereafter, a porous body having a skeleton made of silicon oxide is obtained through a washing treatment with water. The temperature of the water in the washing process with water is generally in the range of room temperature to 100 ° C. The time for the water washing treatment step can be appropriately determined according to the composition, size, etc. of the target glass, but is usually about 1 to 50 hours.

In the phase separation heating step, a silicon oxide rich phase layer that cannot be removed by acid treatment may be formed on the surface of the base glass. In this case, it is preferable to remove the silicon oxide rich phase layer by polishing or the like before acid treatment. As the polishing means, mirror finish using CeO ₂ powder is preferable.

  It is also possible to produce the porous body of the present invention without undergoing phase separation heat treatment or acid treatment. This method includes a step of mixing 4% by weight to 20% by weight of sodium oxide, 10% by weight to 40% by weight of boron oxide, and 50% by weight to 80% by weight of silicon oxide. Next, the mixed material is heated, melted and cooled to obtain a phase-separated base glass, and the base glass is brought into contact with water without being heated again to obtain a porous body. And have.

  A porous body can be obtained by performing a water washing treatment in which the base glass is brought into contact with water. In this method, by specifying the base glass in the composition range, a porous body made of a porous body can be obtained only by washing the base glass with water without undergoing phase separation heat treatment or acid treatment. . In the preferred composition of the mixed material and the base glass used in this production method, the content of sodium oxide is usually 4% by weight or more and 20% by weight or less, and particularly preferably 4.5% by weight or more and 15% by weight or less. The content of boron oxide is usually 10% by weight or more and 40% by weight or less, and particularly preferably 12% by weight or more and 35% by weight or less. The content of silicon oxide is usually 50% by weight or more and 80% by weight or less, and particularly preferably 58% by weight or more and 75% by weight or less.

  By adopting a specific composition, a porous body can be obtained only by washing with water without requiring phase separation heat treatment or acid treatment. Generally, a layer that is difficult to etch is formed on the surface of phase-separated glass, but it is removed by mechanical means of polishing, chemical means of etching with hydrofluoric acid or alkaline aqueous solution, and then an aqueous solution of acid. Etching is performed. The washing treatment is preferably carried out by using water in a neutral region and immersing it in an aqueous solution having a temperature of 50 ° C. or higher and 100 ° C. or lower. The washing time may be about 1 to 50 hours.

  Further, in the base glass of the sodium oxide-boron oxide-silicon oxide system, the total content of sodium oxide, boron oxide and silicon oxide is 95% by weight or more and 100% by weight or less based on the whole phase-separated glass. And The base glass may contain an oxide of three or more components in addition to the above three-component oxide. For example, as silicon oxide base glass, silicon oxide-boron oxide-alkali metal oxide- (alkaline earth metal oxide, zinc oxide, aluminum oxide, zirconium oxide), titanium oxide base glass (silicon oxide-boron oxide-oxidation) And calcium-magnesium oxide-aluminum oxide-titanium oxide) and rare earth base glass (boron oxide-alkali metal oxide- (cerium oxide, thorium oxide, hafnium oxide, lanthanum oxide)). Examples of the third component or more of the fourth component include, but are not limited to, aluminum oxide, zirconium oxide, alkaline earth metal oxide, and the like. The content of the fourth component is less than 5% by weight.

  The sodium oxide-boron oxide-silicon oxide phase-separated glass having the above composition range is the same porous material as that produced by a general manufacturing method even if it is only washed with water without performing heat treatment or acid treatment. You can get a body.

  Next, the manufacturing method of a porous body (porous glass layer) on a base material is demonstrated.

  In order to form a porous body (porous glass layer) on a base material, the base material contains glass powder mainly composed of basic glass obtained by mixing and melting the porous glass forming raw material. Forming a glass powder layer. A step of obtaining a phase-separated glass layer obtained by heat-treating the glass powder layer at a temperature equal to or higher than a glass transition point of the glass powder; and etching the phase-separated glass layer to form a porous spinodal structure having continuous pores. A step of obtaining a glassy glass layer.

  Examples of the manufacturing method include all manufacturing methods capable of forming a glass layer, such as a printing method, a vacuum deposition method, a sputtering method, a spin coating method, a dip coating method, and the manufacturing method capable of achieving the structure of the present invention. Any manufacturing method may be used.

  In the present invention, it is essential to form a spinodal structure in the porous body on the substrate. The formation of the spinodal structure requires precise composition control of the glass. Once the glass composition has been determined, the film formation method that forms the glass powder by fusing and fusing it is easy to control the composition. It is excellent in that it can.

  In the present invention, it is possible to obtain a phase-separated glass layer obtained by subjecting the glass powder layer to heat treatment at a temperature higher than the glass transition point of the glass powder. At a temperature lower than the glass transition point of the glass powder, the fusion of the glass powder does not proceed and no layer is formed. On the other hand, if the glass powder is simply heat-treated, phase separation may not be achieved, and a spinodal porous body (porous glass layer) may not be formed.

  As a result of intensive studies, the present inventors have found that the phenomenon that prevents the formation of the spinodal structure is one of the causes of crystallization in the heat treatment of the glass powder, and the present invention is precisely controlled by controlling the heat treatment conditions. I found out to solve the problem. That is, since the phase separation phenomenon of glass occurs in an amorphous state, when a glass powder is fused and a porous body (glass layer) is formed, a heat treatment method for forming a layer while maintaining the amorphous state is employed. It is thought that it is necessary to choose. As a heat treatment method for forming a layer while maintaining the amorphous state, any means capable of maintaining the amorphous state may be used. For example, a method of suppressing crystal nucleation by performing a heat treatment at a temperature below the crystallization temperature, or suppressing crystal nucleation by quenching from a molten state at a high temperature (above the crystallization temperature) of glass. A method is mentioned.

  Hereinafter, an embodiment of a process of forming a glass powder layer containing glass powder whose main component is a basic glass obtained by mixing and melting the porous body (porous glass) production raw material of the present invention will be described. Specifically, after applying a glass paste containing a glass powder mainly composed of a basic glass obtained by mixing and melting at least a porous glass forming raw material and a solvent on a substrate, the solvent is removed. To form a glass powder layer. Examples of the method for forming the glass powder layer include a printing method, a spin coating method, and a dip coating method.

  Hereinafter, a method using a general screen printing method will be described as an example of a method for forming a glass powder layer containing glass powder.

  In the screen printing method, since glass powder is pasted and printed using a screen printer, preparation of the paste is essential.

  Moreover, since the porous body (porous glass layer) of the present invention is formed by phase separation of glass, it is preferable to use phase-separable base glass capable of phase separation as the glass powder used for the glass paste.

  The material of the phase-separable base glass substrate that forms the spinodal structure of the present invention is not particularly limited. For example, silicon oxide glass I (base glass composition: silicon oxide-boron oxide-alkali metal oxidation) Product), silicon oxide glass II (matrix glass composition: silicon oxide-boron oxide-alkali metal oxide- (alkaline earth metal oxide, zinc oxide, aluminum oxide, zirconium oxide)), titanium oxide glass (matrix glass) (Composition: silicon oxide-boron oxide-calcium oxide-magnesium oxide-aluminum oxide-titanium oxide) and the like. Among them, borosilicate glass of silicon oxide-boron oxide-alkali metal oxide is preferable.

  Furthermore, in the borosilicate glass, a glass having a composition in which the ratio of silicon oxide is 50.0 wt% or more and 80.0 wt% or less, particularly 55.0 wt% or more and 75.0 wt% or less is preferable. When the ratio of silicon oxide is in the above range, phase-separated glass having a high skeleton strength tends to be obtained, which is particularly useful when strength is required.

  The manufacturing method of the phase-separable base glass can be manufactured using a known method except that the raw materials are prepared so as to have the above composition. For example, it can be produced by heating and melting a raw material containing a supply source of each component and forming it into a desired form as necessary. The heating temperature in the case of heating and melting may be appropriately set depending on the raw material composition or the like, but is usually in the range of 1300 to 1450 ° C, particularly 1320 to 1430 ° C.

  For example, sodium oxide, boric acid and silicon dioxide may be uniformly mixed as the raw material and heated and melted at 1300 to 1450 ° C. In this case, as the raw material, any raw material may be used as long as it contains the above-mentioned alkali metal oxide, boron oxide and silicon oxide components.

  In addition, when the phase-separable base glass is formed into a predetermined shape, after synthesizing the phase-separable base glass, it is formed into various shapes such as a tube, a plate, and a sphere in a temperature range of about 1000 to 1200 ° C. good. For example, a method in which the raw material is melted to synthesize a phase-separable base glass and then molded in a state where the temperature is lowered from the melting temperature and maintained at 1000 to 1200 ° C. can be suitably employed.

  In the phase-separated glass that is easily crystallized, it is preferable to use a means for rapid cooling when the temperature is lowered from the melting temperature. By rapid cooling, the formation of crystal nuclei in the glass can be suppressed, and it becomes easy to form an amorphous homogeneous glass layer and phase separation is easily performed.

  For use as a paste, glass is crushed to obtain glass powder. The pulverization method is not particularly limited, and a known pulverization method can be used. Examples of the pulverization method include a liquid phase pulverization method typified by a bead mill and a gas phase pulverization method typified by a jet mill.

  In order to form the glass powder layer containing glass powder, it forms using the paste containing the said glass powder. The paste contains a thermoplastic resin, a plasticizer, a solvent and the like together with the glass powder.

  The ratio of the glass powder contained in the paste is in the range of 30.0 wt% to 90.0 wt%, preferably 35.0 wt% to 70.0 wt%.

  The thermoplastic resin contained in the paste is a component that increases film strength after drying and imparts flexibility. As the thermoplastic resin, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like can be used. These thermoplastic resins can be used alone or in combination.

  The content of the thermoplastic resin contained in the paste is preferably 0.1% by weight or more and 30.0% by weight or less. If it is less than 0.1% by weight, the film strength after drying tends to be weak. When it is larger than 30.0% by weight, it is not preferable because a residual component of the resin tends to remain in the glass when the glass layer is formed.

  Examples of the plasticizer contained in the paste include butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, and dibutyl phthalate. These plasticizers can be used alone or in combination.

  The content of the plasticizer contained in the paste is preferably 10.0% by weight or less. By adding a plasticizer, it is possible to control the drying speed and to give flexibility to the dried film.

  Examples of the solvent contained in the paste include terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate and the like. These solvents can be used alone or in combination.

  The content of the solvent contained in the paste is preferably 10.0% by weight or more and 90.0% by weight or less. If it is less than 10.0% by weight, it tends to be difficult to obtain a uniform film. On the other hand, when it exceeds 90.0% by weight, it tends to be difficult to obtain a uniform film.

  The paste can be produced by kneading the above materials at a predetermined ratio.

  A glass powder layer containing glass powder can be formed by applying the paste on the substrate using a screen printing method and then drying and removing the solvent component of the paste. Moreover, in order to make it the target film thickness, you may apply | coat and dry a glass paste, repeating arbitrary times.

  The temperature and time for drying and removing the solvent can be appropriately changed depending on the solvent used, but it is preferable to provide a leveling step at a temperature lower than the decomposition temperature of the thermoplastic resin to flatten the surface. .

  Next, a step of decomposing the resin of the glass powder layer and obtaining a phase-separated glass layer by performing a heat treatment at or above the glass transition point of the glass powder is performed.

  During this time, the glass powders are fused and phase separated to form a phase separated glass layer.

  Among phase separations, there are binodal type phase separation in which pores are discontinuous and spinodal type phase separation in which pores are continuous.

  Among them, the pores of the porous glass obtained by the spinodal type phase separation structure are three-dimensional network-like continuous continuous pores connected from the surface to the inside, and the porosity can be arbitrarily controlled by changing the heat treatment conditions. It is possible. Moreover, since it is a three-dimensional network-like continuous through-hole, it has high surface strength.

  The decomposition temperature of the thermoplastic resin can be measured using a differential type differential thermobalance (TG-DTA) or the like.

  When fusing the glass powder, a binder removal step is appropriately provided so as not to leave the carbon component of the resin. Moreover, when fusing glass powder, it is preferable to heat-treat at or above the glass transition point of the glass powder, more preferably in the softening temperature region of the glass. When it is lower than the glass transition point, the melting of the glass powder does not proceed and the glass layer tends not to be formed.

  The heat treatment temperature for heat-treating the glass powder is, for example, 200 ° C. or more and 1000 ° C. or less, and the heat treatment time can be appropriately set within the range of 1 hour to 100 hours according to the pore diameter of the obtained porous glass. . A step of phase separation is included in the step of heat-treating the glass powder.

  Further, the heat treatment temperature does not have to be a constant temperature, and the temperature may be continuously changed or may be subjected to a plurality of different temperature steps.

  Next, the phase separation glass layer is etched to obtain a spinodal porous body (porous glass layer) having continuous pores.

  A porous glass layer is obtained by removing the non-skeleton portion of the phase-separated glass layer obtained from the heat treatment step.

  As a means for removing the non-skeleton portion, the soluble phase is generally eluted by contacting with an aqueous solution. The means for bringing the aqueous solution into contact with the glass is generally a means for immersing the glass in the aqueous solution, but is not limited as long as it is a means for bringing the glass and the aqueous solution into contact, such as applying an aqueous solution to the glass.

  As the aqueous solution, any existing solution capable of eluting a soluble phase, such as water, an acid solution, or an alkaline solution, can be used.

  Moreover, you may select multiple types of processes made to contact these aqueous solutions according to a use.

  In general phase-separated glass etching, acid treatment is preferably used from the viewpoint of a small load on the insoluble phase portion and the degree of selective etching. By contacting with an acid solution, an alkali metal oxide-boron oxide rich phase, which is an acid-soluble component, is eluted and removed, while a non-soluble phase has high selective etching properties without impairing stability. .

  As the acid solution, for example, inorganic acids such as hydrochloric acid and nitric acid are preferable. As the acid solution, it is usually preferable to use an aqueous solution containing water as a solvent. What is necessary is just to set the density | concentration of an acid solution suitably in the range of 0.1-2.0 mol / L normally. In some cases, only water may be used.

  In the acid treatment step, the temperature of the acid solution may be in the range of room temperature to 100 ° C., and the treatment time may be about 1 to 500 hours.

  In general, it is preferable to perform water treatment (etching step 2) after treatment with an acid solution or an alkali solution (etching step 1). By performing water treatment, residual components in the porous glass skeleton can be removed, and a more stable porous body (porous glass) tends to be obtained.

  The temperature in the water treatment step is generally preferably in the range of room temperature to 100 ° C. The time for the water treatment step can be appropriately determined according to the composition, size, etc. of the target glass, but is usually about 1 to 50 hours.

  Moreover, in this invention, the etching process can be performed in multiple times as needed.

  First, various evaluation methods in Examples 1 to 3 of the present invention will be described.

<Measuring method of glass transition point (Tg) of glass powder>
The glass transition point (Tg) of the glass powder in the present invention is measured in a DTA curve measured by a differential type differential thermal balance (TG-DTA). As a measuring device, for example, Thermoplus TG8120 (Rigaku Corporation) can be used.

  Specifically, the DTA curve was measured by heating from room temperature at a heating rate of 10 ° C./min using a platinum pan. In the curve, the endothermic onset temperature at the endothermic peak was obtained by extrapolation by the tangent method and used as the glass transition point (Tg).

<Method for measuring crystallization temperature>
The crystallization temperature of the glass powder in the present invention is calculated as follows.

  The glass powder is heat treated at 300 ° C. for 1 hour. The obtained sample was evaluated with an X-ray diffraction structure analyzer (XRD). When a peak due to a crystal was not confirmed, a new glass powder was heat-treated at 350 ° C. higher by 50 ° C. for 1 hour and evaluated by XRD.

  This operation was repeated until the crystal was confirmed, and the temperature at which the peak due to the crystal was confirmed was defined as the crystallization temperature. As the measuring device, for example, RINT2100 (Rigaku Corporation) can be used as XRD.

<Porosity measurement method>
Processing for binarizing the image of the electron micrograph into a skeleton portion and a hole portion was performed. Specifically, using a scanning electron microscope (FE-SEM S-4800, manufactured by Hitachi, Ltd.) at a magnification of 100,000 times (in some cases 50,000 times), which makes it easy to observe the density of the skeleton at an acceleration voltage of 5.0 kV. Observe the surface of the porous glass.

  The observed image is saved as an image, and an image analysis software is used to graph the SEM image at a frequency for each image density. FIG. 12 is a diagram showing the frequency for each porous image density of a spinodal phase separation structure. The peak portion indicated by the down arrow of the image density in FIG. 12 indicates the skeleton portion located in front.

  The bright part (skeleton part) and the dark part (hole part) are binarized into black and white using an inflection point close to the peak position as a threshold value. The average value of all the images was taken for the ratio of the area of the black part to the area of the entire part (the sum of the areas of the white part and the black part), which was defined as the porosity.

<Pore diameter and skeleton diameter measurement method>
Images (electron micrographs) were taken using a scanning electron microscope (FE-SEMS-4800, manufactured by Hitachi, Ltd.) at an acceleration voltage of 5.0 kV at magnifications of 50,000, 100,000, and 150,000 times. From the photographed image, the width of the porous pore portion was measured at 30 points or more, and the average was taken as the pore diameter.

  Similarly, the width of the skeleton portion was measured at 30 points or more, and the average was taken as the skeleton diameter.

<Method for measuring thickness of glass layer>
Using a scanning electron microscope (FE-SEMS-4800, manufactured by Hitachi, Ltd.), an SEM image (electron micrograph) was taken at an acceleration voltage of 5.0 kV and a magnification of 10,000 to 150,000 times. From the photographed image, the thickness of the glass layer portion on the substrate was measured at 30 points or more, and the average value was taken as the thickness of the glass layer.

<Measurement method of main elements>
The main element constituting the base material and the main element constituting the porous glass layer can be measured by quantitative analysis of the constituent elements using, for example, an X-ray photoelectron spectrometer (XPS). As a measuring device, ESCALAB 220i-XL (manufactured by Thermo Scientific) is used.

  A specific measurement method will be described. First, the main element constituting the porous glass layer is analyzed by performing elemental analysis of the outermost surface of the structure of the present invention by XPS.

  Next, the glass layer on the outermost surface is removed by an arbitrary method such as polishing, and after confirming that the glass layer is lost by SEM or the like, the main element of the base material is analyzed by XPS measurement again. Alternatively, the main element of the base material can be analyzed by XPS measurement of the base material portion of the cross section of the structure.

<Measurement method of surface reflectance>
The surface reflectance at a wavelength of 550 nm was measured using a lens reflectance measuring machine (USPM-RU III, manufactured by Olympus Corporation).

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples.

Example 1
Sodium carbonate, boric acid and silicon dioxide were used as glass raw materials, and they were Na ₂ O: B ₂ O ₃ : SiO ₂ : Al ₂ O ₃ = 7.3: 27.2: 62.5: 3.0 (wt% ) Uniform mixing at composition ratio. And it heat-melted at 1350-1450 degreeC, and then naturally cooled in the state shape | molded in plate shape, and obtained the plate-shaped glass of thickness about 1 mm.

Was cut into approximately 1cm square the plate _{glass, 7.3Na 2 O · 27.2B 2 O} 3 · 62.5SiO 2 · 3.0Al 2 O 3 ( wt%) 50 hours the mother glass composition at 540 ° C. Heat treated. The glass was surface polished to remove the surface layer. It was immersed in 1N nitric acid warmed to 80 ° C. for 30 hours and rinsed with ion-exchanged water to obtain a porous glass layer. The result of having observed the glass surface of the obtained porous glass with the electron microscope is shown in FIG. It was found that a spinodal structure was formed. The skeleton diameter was 40 nm, the pore diameter was 30 nm, and the porosity was 35%.

  Moreover, although the obtained porous body was made to absorb water and the crack accompanying water absorption was confirmed, the crack was not seen.

  In addition, after exposing the obtained porous glass and non-porous silica glass to the atmosphere for 2 hours, taking a photograph of dust in a 2 cm × 2 cm region and counting the number, There were 666 silica glasses not attached, whereas 43 silica glasses were attached.

  Moreover, the surface reflectance of the obtained porous glass was 0.6%.

(Example 2)
Sodium carbonate, boric acid and silicon dioxide are used as glass raw materials, and they are composed of Na ₂ O: B ₂ O ₃ : SiO ₂ : Al ₂ O ₃ = 9: 30.5: 59: 1.5 (% by weight) Mix evenly in the ratio. And it heat-melted at 1350-1450 degreeC, and then naturally cooled in the state shape | molded in plate shape, and obtained the plate-shaped glass of thickness about 1 mm.

The base glass having a composition of 9Na ₂ O · 30.5B ₂ O ₃ · 59SiO ₂ · 1.5Al ₂ O ₃ (wt%) obtained by cutting the plate glass into approximately 1 cm square is subjected to a phase separation treatment at 560 ° C. for 25 hours. It was. The glass was surface polished to remove the surface layer. The porous glass layer was obtained by immersing in 1N nitric acid warmed to 80 ° C. for 50 hours and rinsing with ion-exchanged water. When the glass surface of the obtained porous glass was observed with an electron microscope, it was found that a spinodal structure was formed as in Example 1. The skeleton diameter was 35 nm, the pore diameter was 50 nm, and the porosity was 55%.

  In addition, after exposing the obtained porous glass and non-porous silica glass to the atmosphere for 2 hours, taking a photograph of dust in a 2 cm × 2 cm region and counting the number, While 754 non-silica glasses were attached, 55 pieces were attached to the obtained porous glass.

  Moreover, the surface reflectance of the obtained porous glass was 0.5%.

(Example 3)
Sodium carbonate, boric acid and silicon dioxide are used as glass raw materials, and they are uniformly mixed at a composition ratio of Na ₂ O: B ₂ O ₃ : SiO ₂ = 9.3: 28.8: 62.9 (% by weight). did. And it heat-melted at 1350-1450 degreeC, and then naturally cooled in the state shape | molded in plate shape, and obtained the plate-shaped glass of thickness about 1 mm.

The base glass having a composition of 9.3Na ₂ O · 28.8B ₂ O ₃ · 62.9SiO ₂ (% by weight) obtained by cutting the plate glass into approximately 1 cm square was heat-treated at 580 ° C. for 40H to cause phase separation. The glass was surface polished to remove the surface layer. It was immersed in 1N nitric acid warmed to 80 ° C. for 50 H and rinsed with ion-exchanged water to obtain porous glass. When the glass surface of the obtained porous glass was observed with an electron microscope, it was found that a spinodal structure was formed as in Example 1. The skeleton diameter was 45 nm, the pore diameter was 50 nm, and the porosity was 50%.

  In addition, after exposing the obtained porous glass and non-porous silica glass to the atmosphere for 2 hours, taking a photograph of dust in a 2 cm × 2 cm region and counting the number, While 350 silica glasses were attached, 36 pieces were attached to the obtained porous glass.

  Moreover, the surface reflectance of the obtained porous glass was 0.6%.

  Next, implementation methods and evaluation methods in Examples 4 to 9 of the present invention will be described.

<Example of production of glass powder 1>
Feed composition, SiO- ₂ 64 _wt%, B _{2 O} 3 27 wt%, _Na 2 O 6% by weight, _Al 2 _{O 3} 3 in a weight%, quartz powder, boron oxide, sodium oxide, and alumina The mixed powder was melted at 1500 ° C. for 24 hours using a platinum crucible. Thereafter, the glass was lowered to 1300 ° C. and then poured into a graphite mold. After being allowed to cool in the atmosphere for about 20 minutes, it was kept in a slow cooling furnace at 500 ° C. for 5 hours and then cooled for 24 hours. The resulting borosilicate glass block was pulverized using a jet mill until the average particle size became 4.5 μm, whereby glass powder 1 was obtained.

  The crystallization temperature of the glass powder 1 was 800 ° C.

<Example of production of glass powder 2>
A mixed powder of quartz powder, boron oxide and sodium oxide is used so that the charged composition is 63.0 wt% of SiO- ₂ , 28.0 wt% of B ₂ O _{3 and} 9.0 wt% of Na ₂ O. A glass powder 2 was obtained in the same manner as the glass powder 1 except that.

  The crystallization temperature of the glass powder 2 was 750 ° C.

<Example of production of glass paste 1>
Glass powder 1 60.0 parts by mass α-Terpineol 44.0 parts by mass Ethylcellulose (registered trademark ETHOCEL Std 200 (manufactured by Dow Chemical Company))
2.0 parts by weight

  The said raw material was stirred and mixed and the glass paste 1 was obtained. The viscosity of the glass paste 1 was 31300 mPa · s.

<Production example of glass paste 2>
Glass paste 2 was obtained in the same manner as glass paste 1 except that glass powder 2 was used instead of glass powder 1. The viscosity of the glass paste 2 was 38000 mPa · s.

<Examples of base materials 1 to 4>
A quartz substrate (made by Iiyama Special Glass Co., Ltd., softening point 1700 ° C.) was used as the base material 1.

  A sapphire substrate (manufactured by Techno-Chemics Co., Ltd., melting point 2030 ° C.) was used as the base material 2.

  A glass substrate (registered trademark 7059, Corning, softening point 844 ° C.) was used as the base material 3.

  A glass substrate (registered trademark S-TIM 1 manufactured by OHARA INC., Softening point 699 ° C.) was used as the base material 4.

  In addition, each board | substrate used the board | substrate which carried out the mirror polishing of the thing of 1.1 mm thickness cut | disconnected to the magnitude | size of 50 mm x 50 mm.

<Production Example of Structure 1>
The glass paste 1 was applied onto the substrate 1 by screen printing. The printing machine used was MT-320TV manufactured by Microtech. The plate used was a solid image of 30 mm × 30 mm of # 500.

  Subsequently, it was left still for 10 minutes in a 100 degreeC drying furnace, and the solvent part was dried. The film thickness of the formed film was measured by SEM and found to be 10.00 μm.

  This film was heated to 700 ° C. at a heating rate of 20 ° C./min as a heat treatment step 1 and heat-treated for 1 hour. Thereafter, as heat treatment step 2, the temperature was lowered to 600 ° C. at a temperature drop rate of 10 ° C./min, heat treated at 600 ° C. for 50 hours, and the outermost surface of the film was polished to obtain phase-separable glass layer 1.

  The phase-separable glass layer 1 was immersed in a 1.0 mol / L nitric acid aqueous solution heated to 80 ° C. and allowed to stand at 80 ° C. for 24 hours. Then, it was immersed in distilled water heated to 80 ° C. and allowed to stand for 24 hours. The glass body was taken out from the solution and dried at room temperature for 12 hours to obtain a structure 1 in which a porous glass film was formed on a substrate.

  When the film thickness was observed by SEM, formation of a uniform film with a film thickness of 7.00 μm was confirmed. Table 1 shows the manufacturing conditions of 1 of the structure. Table 2 shows the measurement results of each evaluation of the obtained structure 1.

<Example of manufacturing structure 2>
A structure 2 in which a porous glass film was formed on a substrate was obtained in the same manner as in the structure 1 except that the polishing time for the outermost surface of the film when the phase-separable glass layer 1 was produced was extended. When the film thickness was observed by SEM, it was 0.09 μm. Table 2 shows the measurement results of each evaluation of the structure 2 obtained.

<Examples of Structures 3 to 5>
Structures 3 to 5 in which a porous glass film was formed on a substrate were obtained in the same manner as in Structure 1 except that the production conditions shown in Table 1 were changed. Table 2 shows the measurement results of the obtained structures.

<Production Example of Structure 6>
Except changing the base material to be used from the base material 1 to the base material 2, a structure 6 in which a porous glass film was formed on the base material was obtained in the same manner as in the structure 1 described above. Table 2 shows the measurement results of the obtained structure 6.

Example 4
The obtained structure 1 was evaluated by the following evaluation means.

<Evaluation of pore structure>
Using a scanning electron microscope (FE-SEMS-4800, manufactured by Hitachi, Ltd.), an SEM image (electron micrograph) was taken at an acceleration voltage of 5.0 kV and a magnification of 10,000 to 150,000 times. From the photographed image, a continuous pore structure by spinodal type phase separation was judged.
Rank A: A continuous pore structure due to spinodal type phase separation is confirmed.
Rank B: A continuous pore structure due to spinodal phase separation is not confirmed

<Evaluation of structure distortion>
The distortion of the structure was evaluated according to the following criteria. The structure was placed on a flat table, and the distortion was judged based on whether the structure was warped.
Rank A: No warping of the structure is confirmed.
Rank B: Warping of the structure is confirmed.

<Strength evaluation>
The 10 mm portion of each of the opposite sides of the obtained structure was fixed, and a weight of 100 g with an area of 10 mm × 10 mm was placed in the center of the structure, and the strength of the structure was evaluated by whether or not the structure was destroyed. .
Rank A: The structure is not destroyed.
Rank B: The structure is destroyed.

<Evaluation of film adhesion>
The interface between the porous glass layer portion of the obtained structure and the substrate was observed using SEM, and the film adhesion was evaluated. The evaluation criteria are as follows.

The apparatus was a field emission scanning electron microscope S-4800 (trade name) manufactured by Hitachi High-Technologies Corporation, and was observed at an acceleration voltage of 5.0 kV and a magnification of 150,000 times. Specifically, film adhesion was judged by whether or not the interface between the skeleton portion of the porous glass layer and the substrate was observed.
Rank A: The interface between the porous glass skeleton part and the substrate is not observed.
Rank B: The interface between the porous glass skeleton and the substrate is clearly observed.

<Dustproof evaluation>
One piece of the structure 4 and silica glass that is not a porous body of 5 cm × 5 cm were exposed to the atmosphere for 4 hours, and then a 20 × 20 mm region was photographed and the number of dust was counted.
Rank A: 1/10 or less of the number on the silica glass.
Rank B: More than 1/10 and less than 1/5 of the number on the silica glass.
Rank C: 1/5 or more of the number on the silica glass.

(Examples 5 to 9)
The structures 2 to 6 were evaluated by the same evaluation means as in Example 4. The evaluation results are shown in Table 3.

(Example 10)
A porous glass was obtained in the same manner as in Example 1 except that the base glass was heat-treated at 520 ° C. for 80 hours and phase-separated. When the glass surface of the obtained porous glass was observed with an electron microscope, it was found that a spinodal structure was formed as in Example 1. The skeleton diameter was 10 nm, the pore diameter was 20 nm, and the porosity was 35%.

  The obtained porous glass and non-porous silica glass were exposed to the atmosphere for 2 hours, then dust was photographed in a 2 cm × 2 cm region, and the number was counted. While 620 glasses were attached, 20 pieces were attached to the obtained porous glass.

  Moreover, the surface reflectance of the obtained porous glass was 0.8%.

(Example 11)
A porous glass was obtained in the same manner as in Example 1 except that the base glass was heat-treated at 600 ° C. for 30 hours and phase-separated. When the glass surface of the obtained porous glass was observed with an electron microscope, it was found that a spinodal structure was formed as in Example 1. The skeleton diameter was 70 nm, the pore diameter was 60 nm, and the porosity was 60%.

  The obtained porous glass and non-porous silica glass were exposed to the atmosphere for 2 hours, then dust was photographed in a 2 cm × 2 cm region, and the number was counted. While 620 pieces of glass were attached, 100 pieces were attached to the obtained porous glass.

  Moreover, the surface reflectance of the obtained porous glass was 0.5%.

(Example 12)
A porous glass was obtained in the same manner as in Example 1 except that the base glass was heat-treated at 470 ° C. for 25 hours and phase-separated. However, the phase-separated glass was weak and it was easy to crack when dried. When the glass surface of the obtained porous glass was observed with an electron microscope, it was found that a spinodal structure was formed as in Example 1. The skeleton diameter was 2 nm and the pore diameter was 6 nm.

  The obtained porous glass and non-porous silica glass were exposed to the atmosphere for 2 hours, then dust was photographed in a 2 cm × 2 cm region, and the number was counted. While 623 glasses were adhered, 175 obtained porous glasses were adhered. Since the skeleton diameter is small and dust is adsorbed across two or more skeletons, it is considered that the adhesion of dust is larger than in Example 10 or 11.

(Example 13)
A porous glass was obtained in the same process as in Example 1, except that the base glass was heat-treated at 610 ° C. for 50 hours and phase-separated. When the glass surface of the obtained porous glass was observed with an electron microscope, it was found that a spinodal structure was formed as in Example 1. The skeleton diameter was 100 nm, the pore diameter was 100 nm, and the porosity was 70%.

  The obtained porous glass and non-porous silica glass were exposed to the atmosphere for 2 hours, then dust was photographed in a 2 cm × 2 cm region, and the number was counted. While 600 pieces of glass were attached, 180 pieces were attached to the obtained porous glass.

  From the above, it was found that a structure having a spinodal structure has high strength and a high dustproof effect. Moreover, it turned out that the structure which has frame | skeleton diameter 5 nm or more and 80 nm or less has a high dustproof effect.

Claims (11)

An image pickup apparatus for forming a subject image from a lens on an image pickup device through an optical filter, the porous filter on the opposite side of the optical filter from the image pickup device,
The imaging device according to claim 1, wherein the porous body has three-dimensionally communicating holes derived from spinodal type phase separation.   The imaging device according to claim 1, wherein the hole is exposed to the atmosphere on a surface of the porous body opposite to the optical filter.   3. The imaging device according to claim 1, wherein an average skeleton diameter of the surface of the porous body is 5 nm or more and 50 nm or less.   The imaging device according to any one of claims 1 to 3, wherein an average pore diameter of the surface of the porous body is 5 nm or more and 500 nm or less.   The imaging device according to any one of claims 1 to 4, wherein the porosity of the porous body is 10% or more and 90% or less.   6. The imaging apparatus according to claim 1, wherein the porous body has a skeleton made of silicon oxide.   The imaging apparatus according to claim 1, wherein the optical filter is a low-pass filter and / or an infrared cut filter.   The imaging device according to claim 1, wherein the porous body is integrally formed on a surface of quartz or quartz glass. An image forming apparatus having an optical device used for irradiating light to form an image,
An image forming apparatus, wherein the dust-proof glass provided in the optical device has a porous body having holes communicating with each other three-dimensionally derived from spinodal phase separation.   The image forming apparatus according to claim 9, wherein the hole is exposed to the atmosphere on a surface of the porous body.   The image forming apparatus according to claim 9, wherein the porous body is integrally formed on a surface of the heat resistant glass.