JP2004061899A - Method for manufacturing nd filter, and nd filter, and light quantity reducing device and camera having such nd filter - Google Patents

Method for manufacturing nd filter, and nd filter, and light quantity reducing device and camera having such nd filter Download PDF

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Publication number
JP2004061899A
JP2004061899A JP2002220762A JP2002220762A JP2004061899A JP 2004061899 A JP2004061899 A JP 2004061899A JP 2002220762 A JP2002220762 A JP 2002220762A JP 2002220762 A JP2002220762 A JP 2002220762A JP 2004061899 A JP2004061899 A JP 2004061899A
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Japan
Prior art keywords
nd filter
outermost layer
film
mask
film thickness
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JP2002220762A
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Japanese (ja)
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JP3685331B2 (en
Inventor
Fumie Ishii
Shinji Uchiyama
Takayuki Wakabayashi
Michio Yanagi
内山 真志
柳 道男
石井 史江
若林 孝幸
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Canon Electronics Inc
キヤノン電子株式会社
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Application filed by Canon Electronics Inc, キヤノン電子株式会社 filed Critical Canon Electronics Inc
Priority to JP2002220762A priority Critical patent/JP3685331B2/en
Priority claimed from CN 03150007 external-priority patent/CN1243279C/en
Priority claimed from US10/630,483 external-priority patent/US6984044B2/en
Publication of JP2004061899A publication Critical patent/JP2004061899A/en
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Abstract

An object of the present invention is to provide a method of manufacturing an ND filter having a low-cost gradation density distribution and capable of coping with high image quality without deteriorating image quality due to light scattering, and an ND filter.
In manufacturing an ND filter by forming at least two or more types of films on a plastic substrate, a mask having a halftone dot pattern for forming a gradation concentration distribution is formed on a film other than the outermost layer. On the other hand, the outermost layer is formed to a constant thickness without using a mask.
[Selection] Fig. 6

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an ND filter, an ND filter, and a light-amount aperture device and a camera having the ND filter, and particularly to an ND having a gradation density distribution suitable for use in an imaging system such as a video camera or a still video camera. The present invention relates to a method for manufacturing a filter, an ND filter, and a light-amount aperture device having these ND filters.
[0002]
[Prior art]
The light amount aperture device is provided in the optical path of the photographing optical system in order to control the amount of light incident on the solid-state imaging device such as a silver halide film or a CCD, and to reduce the amount of light to be smaller when the field is bright. Is configured.
Therefore, when shooting a sunny or high-brightness scene, the aperture becomes small, which is easily affected by the hunting phenomenon of the aperture and the diffraction of light, resulting in deterioration of image performance.
As a countermeasure against this, a film-like ND (Neutral Density) filter is attached to the aperture blade so that the aperture of the aperture becomes large even if the brightness of the field is the same.
[0003]
In recent years, as the sensitivity of an image sensor has been improved, the density of the ND filter has been increased to further reduce the light transmittance, and the aperture of the diaphragm has been increased even if the brightness of the object field is the same. . However, when the density of the ND filter is increased as described above, the light quantity difference between the light a passing through the ND filter and the light b not passing through the ND filter in the state shown in FIG. There are drawbacks such as the "shading" phenomenon and the reduction in resolution. In order to solve this drawback, it has become necessary to adopt a structure in which the transmittance of the density of the ND filter increases gradually toward the center of the optical axis.
[0004]
Incidentally, in FIG. 8, reference numerals 806A, 806B, 806C, and 806D denote lenses constituting the photographing optical system 806, 807 denotes a solid-state image sensor, and 808 denotes a low-pass filter. Reference numerals 811 to 814 denote members constituting an aperture device, 811 denotes an ND filter, and 812 and 813 move in opposite directions. The two aperture blades form a substantially rhombic opening. The ND filter is usually bonded to the diaphragm blade. 814 is a diaphragm blade support plate.
[0005]
[Problems to be solved by the invention]
Generally, ND filters are manufactured by mixing and kneading an organic dye or pigment that absorbs light into a film-like material (cellulose acetate, PET (polyethylene terephthalate), vinyl chloride, etc.), There is a type in which an organic dye or pigment that absorbs light is applied to the material. With these manufacturing methods, a filter having a uniform density can be manufactured, but it is extremely difficult to manufacture a filter (gradation filter) in which the density changes within the same filter.
[0006]
Regarding such a variable density type (gradation type) ND filter, the present inventors have disclosed Japanese Patent No. 2754518 (Japanese Patent Application Laid-Open No. 05-281593), Japanese Patent No. 2771078 (Japanese Patent Application Laid-Open No. 06-095208), and Japanese Patent No. 2771084. Japanese Patent Application Laid-Open No. 06-175193 proposes a method of producing a variable density (gradation type) ND filter by a microphotography. In video cameras at the time, image quality was improved by using an ND filter manufactured by this method. However, in recent years, CCDs have been used in special conditions due to their higher sensitivity, smaller size, and higher image quality (for example, under backlighting). (Small-diameter aperture state), the image quality may be degraded due to the influence of light scattering by the silver salt particles.
[0007]
Japanese Patent Application Laid-Open No. 11-38206 discloses a method for manufacturing an elliptical gradation filter by a vacuum evaporation method. This method has a disadvantage that the density cannot be changed in a very small area (for example, a change from 3% to 80% in a range of 3 mm).
[0008]
Further, as a measure against the above-mentioned high image quality, a single-density ND filter is adhered to a plurality of aperture blades and driven to change the density of the single-density filter from the overlapping portion and the non-overlapping portion. It is possible. However, this method has disadvantages such as an increase in cost due to an increase in the number of ND filters, and an increase in the thickness due to the presence of a plurality of ND filters in the aperture blade, which makes it impossible to cope with recent miniaturization and space saving.
[0009]
Therefore, the present invention provides a method of manufacturing an ND filter having a low-cost gradation density distribution, which does not cause deterioration in image quality due to light scattering and can respond to high image quality, and an ND filter, and these ND filters It is an object of the present invention to provide a light-aperture stop device and a camera, which can improve the uniformity of the light amount.
[0010]
[Means for Solving the Problems]
The present invention provides a method of manufacturing an ND filter having a gradation density distribution configured as described in the following (1) to (11), an ND filter, and a light amount diaphragm device and a camera having these ND filters. .
(1) In manufacturing an ND filter by forming at least two or more types of films on a substrate, films other than the outermost layer are formed using a mask having a halftone dot pattern for forming a gradation concentration distribution. A method for manufacturing an ND filter, comprising: forming a film; and forming a film of the outermost layer without using the mask.
(2) The mask having the halftone dot pattern, wherein the hole diameter of the halftone dot pattern and the distance between the centers of the holes change stepwise or steplessly. The method for manufacturing an ND filter according to 1).
(3) The mask having the halftone dot pattern is used by setting a distance from the substrate to a range of 1 mm to 50 mm.
The method for producing an ND filter according to (1) or (2).
(4) a step of heat-treating the formed substrate in air at a temperature of 100 ° C. to 130 ° C. after forming the film of the outermost layer subsequent to the film other than the outermost layer. The method for producing an ND filter according to any one of the above (1) to (3).
(5) The outermost layer is formed to have a constant thickness of 1 / 4λ (λ = 500 nm to 600 nm) with an optical film thickness n × d (where n is a refractive index and d is a mechanical film thickness). The method for manufacturing an ND filter according to any one of the above (1) to (4), wherein
(6) The method for producing an ND filter according to (5), wherein the refractive index n is 1.5 or less in a visible wavelength range.
(7) An ND filter having at least two or more types of films on a substrate, wherein the at least two or more types of films are formed in a stepwise manner since each of the films from the first layer to the outermost layer forms a gradation concentration distribution. Alternatively, the ND filter is configured to have a continuously changing film thickness, and the outermost layer film has a constant film thickness.
(8) The film of the outermost layer has an optical film thickness of n × d (where n is a refractive index and d is a mechanical film thickness) and is λλ (λ = 500 nm to 600 nm).
The ND filter according to the above (7).
(9) The ND filter according to (8), wherein the refractive index n is 1.5 or less in a visible wavelength range.
(10) A plurality of aperture blades that are relatively driven to change the size of the aperture opening, and an ND filter for adjusting the amount of light disposed at least in a part of the opening formed by the aperture blade. Light intensity diaphragm device,
The ND filter is configured by the ND filter manufactured by the manufacturing method according to any one of (1) to (6) or the ND filter according to any one of (7) to (9). A light amount diaphragm device characterized by the above-mentioned.
(11) A camera comprising: an optical system; a light amount stop device according to (10) for limiting the amount of light passing through the optical system; and a solid-state imaging device for receiving an image formed by the optical system. .
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described.
In the present embodiment, when producing an ND filter having a concentration distribution, a film formation method such as a vacuum film formation method such as a vapor deposition method and a sputtering method, an ink jet printing method, and a spray method is used. First, in order to form a density change pattern in an ND filter, a halftone dot mask is set between a film generation source (evaporation source, ink jet head, spray gun) and a plastic substrate of the ND filter. The film is formed from the layer to the front of the outermost layer. After that, the outermost layer is formed without setting the halftone mask. Through such a process, it is possible to create an ND filter of a variable density type (gradation type) that can support high image quality.
[0012]
Specifically, for example, a vacuum deposition method was used as a film formation method, and the hole diameter of the halftone dot pattern and the distance between the centers of the holes were formed on a plastic substrate so as to change stepwise or steplessly. A halftone dot mask is floated and set in a range of 1 mm to 50 mm from the plastic substrate, and a film whose film thickness changes stepwise or continuously from the first layer to the outermost layer using at least two types of films. Is formed.
[0013]
For example, when the vacuum evaporation method is used, the hole diameter of the halftone dot pattern as shown in FIG. 2 or 3 and the distance between the centers of the holes change stepwise or steplessly on the film formation side of the substrate. By providing such a mask, films having different film thickness distributions are formed on the above-mentioned substrate due to the positional relationship and the like.
[0014]
Such a change in the film thickness distribution may be caused by a mask shape such as a stepwise or stepless change in the hole diameter of the halftone dot pattern and the center of the hole, or the distance between the substrate and the mask. It will be different depending on etc. Therefore, by adjusting the hole diameter of the halftone dot pattern and the distance between the centers of the holes, or the distance between the substrate and the mask, a film having an arbitrary thickness distribution is formed on the substrate. It becomes possible. Here, increasing the film thickness means that the concentration of the film increases and the transmittance decreases, and thus obtaining an arbitrary film thickness distribution is, in other words, an object of the present invention. This means that an arbitrary gradation concentration distribution can be obtained.
[0015]
As described above, after forming a film whose film thickness changes stepwise or continuously, the refractive index n is not more than 1.5 in the wavelength region of the visible region of the film without using a halftone mask. By forming the outermost layer having a thickness of 条件 λ = 500 nm to 600 nm in terms of the optical thickness (n × d), the reflection characteristics can be improved.
[0016]
【Example】
Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto.
[Example 1]
In Example 1, first, of the film configuration shown in FIG. 7 on a plastic substrate (hereinafter referred to as a PET substrate) having a material thickness of 75 μm by vacuum evaporation, It was formed as follows.
In the present embodiment, a halftone dot mask that changes stepwise as shown in FIG. 2 was used and set as shown in FIG.
In addition, a vacuum deposition method was selected as a film formation method because the film thickness can be controlled relatively easily and scattering is very small in a visible wavelength range.
As the material of the substrate, PET was selected, which has high heat resistance (glass transition point Tg), high transparency in the visible wavelength range, and low water absorption.
At that time, the distance d between the PET substrate and the mask was 30 mm.
[0017]
Then, the halftone dot mask was removed, and the outermost layer was formed to a constant thickness under the conditions of an optical film thickness nxd (n is a refractive index, d is a mechanical film thickness) and λλ: 540 nm. The refractive index n of the film on the outermost layer was selected to be 1.5 or less in the visible wavelength range. Specifically, MgF 2 It was used.
[0018]
As described above, after forming the film from the first layer to the outermost layer, heat treatment was performed at 110 ° C. for 1 hour in the air. The reason for choosing 110 ° C. is that if the temperature is lower than 100 ° C., the effect of environmental stability is insufficient. If the temperature exceeds 130 ° C., the substrate is thermally degraded, and problems such as cracks in the film occur. Therefore, the temperature of the heat treatment is suitably between 110 ° C and 130 ° C.
[0019]
The relationship between the density (D) and the transmittance (T) is D = Log 10 1 / T = -Log 10 There is a relationship of T.
What is important here is the hole diameter of the halftone dot mask, the distance between the centers of the holes, and the distance d between the PET substrate and the mask. Since a desired density pattern can be obtained by the hole diameter of the halftone dot mask and the distance between the centers of the holes, these may be selected as needed as needed.
[0020]
The distance d between the PET substrate and the mask is suitably from 1 mm to 50 mm.
When the distance d is smaller than 1 mm, the density pattern formed on PET becomes a halftone dot, and a high density portion and a portion of the PET base material that is not deposited at all are formed. Improvement cannot be achieved. This is because a pattern in which the density gradually changes is good for improving the image quality, but a portion having a large density difference is formed. On the other hand, if the distance d is larger than 50 mm, the wraparound of the film becomes large, the density pattern formed on the PET base material of the mask becomes uniform, and a favorable density change cannot be obtained.
[0021]
In order to examine the environmental stability, the plastic ND filter was subjected to a standing test at 60 ° C. and 85% for 240 hours, and the transmittance was measured before and after the test. . As a reference, a similar environmental test was performed on a sample not subjected to the heat treatment, and the transmittance before and after the test was increased by about 2%.
[0022]
The cause of such a phenomenon is that the substrate temperature during vacuum deposition is low.
The sealing temperature of the film is greatly affected by the substrate temperature at the time of film formation. If the temperature is low, the sealing density is low, and moisture and oxygen are easily transmitted. x O y Promotes oxidation of itself, and protects Al 2 O 3 It is considered that the transmittance increases due to both effects of the protection effect of the dielectric film such as the film being small. It is considered that the environmental stability is improved by performing the above-described heat treatment due to the “aging effect”.
[0023]
After the first layer to the outermost layer are formed as described above, a pattern as shown in FIG. 4A is formed and cut out as a substantially triangular ND filter. Then, as shown in FIG. 1 is attached to the aperture blade 2 and used in a light amount aperture device. The aperture device is the same as that described with reference to FIG. 8, and includes a plurality of aperture blades that are relatively driven to change the size of the aperture opening. One filter is as shown in FIG. 4 (b), where 0 is the end face and X 1 X 2 X 3 The area up to is the density change area. X 3 To X 4 Indicates that the darkest uniform concentration is formed. X 4 To X 5 Is a bonding area for bonding the filter to the blade.
[0024]
In this embodiment, the relationship between the distance (X) and the film thickness of the first to eighth layers and the ninth layer (the outermost layer) is as shown in FIGS.
Further, the relationship between the distance (X) and the transmittance and the relationship between the distance (X) and the reflectance are as shown in FIGS.
Further, the spectral transmittance was as shown in FIG. 13 and the spectral reflectance was as shown in FIG.
[0025]
[Example 2]
In Example 2, first, of the film configuration shown in FIG. 7, the first layer to the outermost layer were formed on a 75 μm-thick PET base material by a vacuum deposition method as follows.
In the present embodiment, a halftone dot mask that changes continuously as shown in FIG. 3 was used and set as shown in FIG.
In addition, a vacuum deposition method was selected as a film formation method because the film thickness can be controlled relatively easily and scattering is very small in a visible wavelength range.
As the material of the substrate, PET having high heat resistance (glass transition point Tg), high transparency in the visible wavelength range, and low water absorption was selected.
At that time, the distance d between the PET substrate and the mask was 30 mm.
[0026]
Next, the halftone dot mask was removed, and the outermost layer was formed with an optical film thickness of n × d (n is a refractive index, d is a mechanical film thickness) and 1 / λ: 540 nm. The refractive index n of the outermost layer film was selected to be 1.5 or less in the visible wavelength range. Specifically, MgF 2 It was used.
[0027]
As described above, after forming the film from the first layer to the outermost layer, heat treatment was performed at 110 ° C. for 1 hour in the air. The reason for selecting 110 ° C. is the same as in Example 1.
Further, since a desired density pattern can be obtained 99 by the hole diameter of the halftone dot mask and the distance between the centers of the holes, these can be selected as needed, if necessary, and the distance d between the PET base material and the mask. It is also the same as in Example 1 that 1 mm to 50 mm is appropriate.
Further, in order to examine the environmental stability, the plastic ND filter was subjected to a standing test at 60 ° C. and 85% for 240 hours in the same manner as in Example 1. As a result, the same result as in Example 1 was obtained.
[0028]
After the first layer to the outermost layer are formed as described above, a pattern as shown in FIG. 5A is formed, cut out as a substantially triangular ND filter, and then, as shown in FIG. A state where 1 is attached to the aperture blade 2 is used for a light amount aperture device as shown in FIG. One filter is as shown in FIG. 5 (b), where 0 is the end face and X 1 X 2 X 3 The area up to is the density change area. X 3 To X 4 Indicates that the darkest uniform concentration is formed. X 4 To X 5 Is a bonding area for bonding the filter to the blade.
[0029]
In this embodiment, the relationship between the distance (X) and the film thickness of the first to eighth layers and the ninth layer (outermost layer) is as shown in FIGS.
Further, the relationship between the distance (X) and the transmittance, and the relationship between the distance (X) and the reflectance are as shown in FIGS.
Further, the spectral transmittance was as shown in FIG. 19, and the spectral reflectance was as shown in FIG.
[0030]
[Example 3]
In Example 3, first, out of the film configuration shown in FIG. 7 from the first layer to the outermost layer in the film configuration shown in FIG. 7 was formed as follows on a PET substrate having a material thickness of 75 μm.
In the present embodiment, a halftone dot mask that changes continuously as shown in FIG. 3 was used and set as shown in FIG.
In addition, a vacuum deposition method was selected as a film formation method because the film thickness can be controlled relatively easily and scattering is very small in a visible wavelength range.
As the material of the substrate, PET having high heat resistance (glass transition point Tg), high transparency in the visible wavelength range, and low water absorption was selected.
At that time, the distance d between the PET substrate and the mask was 30 mm.
[0031]
Next, the halftone dot mask was removed, and the outermost layer was formed with an optical film thickness of n × d (n is a refractive index, d is a mechanical film thickness) and 1 / λ: 540 nm. The refractive index n of the outermost layer film was selected to be 1.5 or less in the visible wavelength range. Specifically, MgF 2 It was used.
In the present embodiment, the subsequent heat treatment in air in Examples 1 and 2 was not performed.
[0032]
In order to check the environmental stability, the plastic ND filter was subjected to a standing test at 60 ° C. and 85% for 240 hours, and the transmittance before and after the test was found to have increased from 1.0% to 3.0%.
The reason why the change before and after the environmental test is large is that the substrate temperature during vacuum deposition is low. The sealing temperature of the film is greatly affected by the substrate temperature at the time of film formation. When the temperature is low, the sealing density is low, and moisture and oxygen are easily transmitted. x O y Promotes oxidation of itself, and protects Al 2 O 3 The transmittance increases due to both effects of a low protection effect of a dielectric film such as a film.
Generally, when a glass substrate is used, the film is formed by heating the substrate at a temperature of 200 ° C. to 250 ° C., preferably about 300 ° C.
However, when the substrate is made of plastic as in this case, it is necessary to form a film at a temperature at which the substrate does not undergo thermal shrinkage.
[0033]
In this embodiment, the relationship between the distance (X) and the film thickness of the first to eighth layers and the ninth layer (outermost layer) is as shown in FIGS.
Further, the relationship between the distance (X) and the transmittance, and the relationship between the distance (X) and the reflectance are as shown in FIGS.
Further, the spectral transmittance was as shown in FIG. 25, and the spectral reflectance was as shown in FIG.
[0034]
(Comparative Example 1)
In Comparative Example 1, all the layers from the first layer to the ninth layer were gradually changed in thickness from a first layer to a ninth layer on a PET base material having a thickness of 75 μm by a vacuum evaporation method, and the film shown in FIG. The configuration was formed as follows.
In the present comparative example, a halftone dot mask that changes stepwise as shown in FIG. 2 was used and set as shown in FIG.
In addition, a vacuum deposition method was selected as a film formation method because the film thickness can be controlled relatively easily and scattering is very small in a visible wavelength range.
As the material of the substrate, PET having high heat resistance (glass transition point Tg), high transparency in the visible wavelength range, and low water absorption was selected.
At that time, the distance d between the PET substrate and the mask was 30 mm.
[0035]
In this comparative example, the relationship between the distance (X) and the film thickness of the first to eighth layers and the ninth layer (outermost layer) is as shown in FIG. As shown in FIG. 27, when each film thickness is changed stepwise including the outermost layer, the reflectance increases, and the "ghost" and "flare" phenomena occur as image quality degradation.
The relationship between the distance (X) and the transmittance and the relationship between the distance (X) and the reflectance are as shown in FIGS.
Further, the spectral transmittance was as shown in FIG. 30, and the spectral reflectance was as shown in FIG.
[0036]
(Comparative Example 2)
In Comparative Example 2, all the layers from the first layer to the ninth layer were gradually changed in thickness by a vacuum evaporation method on a 75 μm-thick PET base material to form a film shown in FIG. The configuration was formed as follows.
In the present comparative example, a halftone dot mask that changes stepwise as shown in FIG. 2 was used and set as shown in FIG.
In addition, a vacuum deposition method was selected as a film formation method because the film thickness can be controlled relatively easily and scattering is very small in a visible wavelength range.
As the material of the substrate, PET having high heat resistance (glass transition point Tg), high transparency in the visible wavelength range, and low water absorption was selected.
At that time, the distance d between the PET substrate and the mask was 30 mm.
[0037]
In this comparative example, the relationship between the distance (X) and the film thickness of the first to eighth layers and the ninth layer (outermost layer) is as shown in FIG. As shown in FIG. 32, when each film thickness is continuously changed including the outermost layer, the reflectance increases, and the "ghost" and "flare" phenomena occur as image quality deterioration.
Further, the relationship between the distance (X) and the transmittance and the relationship between the distance (X) and the reflectance are as shown in FIGS.
Further, the spectral transmittance was as shown in FIG. 35, and the spectral reflectance was as shown in FIG.
[0038]
As described above, the film thickness is changed stepwise or continuously from the first layer to just before the outermost layer, and only the thickness of the outermost layer is such that the refractive index n is 1.5 or less in the visible wavelength region. By using a film and setting the optical film thickness to a constant value of 4λ = 500 nm to 600 nm, the reflectance can be reduced.
[0039]
Normally, the antireflection condition of a single-layer film is when the wavelength used is λ and the optical film thickness is 4λ.
The smaller the refractive index n of the film, the lower the reflectance.
In this case, when the film thicknesses from the first layer to the outermost layer change stepwise or continuously, the optimum film thickness of the outermost layer is from 1 / λλ = 500 nm as the optical film thickness n × d. 600 nm is appropriate. Outside of this range, the reflectance increases.
[0040]
【The invention's effect】
According to the present invention, there is provided a method of manufacturing an ND filter having a low-cost gradation density distribution capable of coping with high image quality without deteriorating image quality due to light scattering, an ND filter, and these ND filters And a camera capable of improving the uniformity of the light amount and a camera.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a state where a gradation ND filter obtained by the present invention is attached to an aperture blade.
FIG. 2 is a diagram showing a stepwise changed halftone mask used in the first embodiment of the present invention.
FIG. 3 is a diagram showing a stepwise changed halftone mask used in a second embodiment of the present invention.
4A and 4B are views for explaining a press-cutting state at the time of manufacturing a filter according to the first embodiment of the present invention, wherein FIG. 4A shows a cutout pattern having a substantially triangular shape, and FIG. The figure which shows the structure of the shape ND filter.
5A and 5B are views for explaining a press-cutting state in manufacturing a filter according to the second embodiment of the present invention, wherein FIG. 5A is a view showing a substantially triangular cutout pattern, and FIG. The figure which shows the structure of the shape ND filter.
FIG. 6 is a schematic view of a method of setting a PET base and a mask for describing examples and comparative examples of the present invention.
FIG. 7 is a diagram showing a film configuration of a vapor deposition ND filter for explaining an example of the present invention and a comparative example.
FIG. 8 is a schematic diagram of a photographing apparatus having an aperture device for explaining the present invention.
FIG. 9 is a graph showing a change in film thickness in Example 1 of the present invention.
FIG. 10 is a film thickness change characteristic diagram according to the first embodiment of the present invention.
FIG. 11 is a transmittance characteristic diagram according to the first embodiment of the present invention.
FIG. 12 is a reflectance characteristic diagram according to the first embodiment of the present invention.
FIG. 13 is a diagram showing a spectral transmittance in the first embodiment of the present invention.
FIG. 14 is a view showing a spectral reflectance in Example 1 of the present invention.
FIG. 15 is a film thickness change characteristic diagram according to the second embodiment of the present invention.
FIG. 16 is a film thickness change characteristic diagram in Example 2 of the present invention.
FIG. 17 is a transmittance characteristic diagram according to the second embodiment of the present invention.
FIG. 18 is a reflectance characteristic diagram according to the second embodiment of the present invention.
FIG. 19 is a diagram showing a spectral transmittance in a second embodiment of the present invention.
FIG. 20 is a diagram showing the spectral reflectance in Example 2 of the present invention.
FIG. 21 is a diagram showing a film thickness change characteristic in Example 3 of the present invention.
FIG. 22 is a film thickness change characteristic diagram in Example 3 of the present invention.
FIG. 23 is a transmittance characteristic diagram according to the third embodiment of the present invention.
FIG. 24 is a reflectance characteristic diagram according to the third embodiment of the present invention.
FIG. 25 is a view showing a spectral transmittance in a third embodiment of the present invention.
FIG. 26 is a diagram showing the spectral reflectance in Embodiment 3 of the present invention.
FIG. 27 is a graph showing a change in film thickness in Comparative Example 1.
FIG. 28 is a transmittance characteristic diagram in Comparative Example 1.
FIG. 29 is a graph showing reflectance characteristics in Comparative Example 1.
FIG. 30 is a view showing a spectral transmittance in Comparative Example 1.
FIG. 31 is a view showing a spectral reflectance in Comparative Example 1.
FIG. 32 is a graph showing a change in film thickness in Comparative Example 2.
FIG. 33 is a graph showing transmittance characteristics in Comparative Example 2.
FIG. 34 is a reflectance characteristic diagram in Comparative Example 2.
FIG. 35 shows the spectral transmittance of Comparative Example 2.
FIG. 36 shows the spectral reflectance in Comparative Example 2.
[Explanation of symbols]
1: ND filter
2: Aperture blade
806A, 806B, 806C,
806D: Lens constituting imaging optical system 806
807: solid-state image sensor
808: Low pass filter
811: ND filter
812, 813: Aperture blade
814: diaphragm blade support plate

Claims (11)

  1. In forming at least two types of films on a substrate to manufacture an ND filter, a process of forming films other than the outermost layer using a mask having a halftone dot pattern for forming a gradation concentration distribution. And forming a film of the outermost layer without using the mask.
  2. 2. The mask having the halftone dot pattern, wherein the distance between the hole diameter and the center of the halftone dot pattern changes stepwise or steplessly. 3. Manufacturing method of the ND filter.
  3. 3. The method according to claim 1, wherein the mask having the halftone dot pattern is used by setting a distance from the substrate to a range of 1 mm to 50 mm. 4.
  4. The method according to claim 1, further comprising, after forming the film on the outermost layer following the film other than the outermost layer, performing a heat treatment on the formed substrate in air at a temperature of 100 ° C to 130 ° C. The method for manufacturing an ND filter according to any one of claims 1 to 3.
  5. The film of the outermost layer is formed to have a constant thickness of λλ (λ = 500 nm to 600 nm) with an optical film thickness n × d (where n is a refractive index and d is a mechanical film thickness). The method for manufacturing an ND filter according to claim 1.
  6. The method according to claim 5, wherein the refractive index n is 1.5 or less in a visible wavelength range.
  7. An ND filter having at least two types of films on a substrate, wherein the at least two types of films are stepwise or continuous because each of the films from the first layer to the outermost layer forms a gradation concentration distribution. ND filter characterized in that the thickness of the outermost layer is configured to be constant.
  8. The film of the outermost layer has an optical film thickness of n × d (where n is a refractive index and d is a mechanical film thickness) and is λλ (λ = 500 nm to 600 nm). ND filter.
  9. The ND filter according to claim 8, wherein the refractive index n is 1.5 or less in a visible wavelength range.
  10. A light amount aperture provided with a plurality of aperture blades that are relatively driven to change the size of the aperture opening, and an ND filter for adjusting a light amount disposed at least in a part of the opening formed by the aperture blades In the device,
    The ND filter is configured by the ND filter manufactured by the manufacturing method according to any one of claims 1 to 6, or the ND filter according to any one of claims 7 to 9. Characteristic light stop device.
  11. 11. A camera comprising: an optical system; a light amount stop device according to claim 10 for limiting a light amount passing through the optical system; and a solid-state imaging device for receiving an image formed by the optical system.
JP2002220762A 2002-07-30 2002-07-30 Manufacturing method of ND filter, light quantity diaphragm device and camera having these ND filters Active JP3685331B2 (en)

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JP2002220762A JP3685331B2 (en) 2002-07-30 2002-07-30 Manufacturing method of ND filter, light quantity diaphragm device and camera having these ND filters

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2002220762A JP3685331B2 (en) 2002-07-30 2002-07-30 Manufacturing method of ND filter, light quantity diaphragm device and camera having these ND filters
CN 03150007 CN1243279C (en) 2002-07-30 2003-07-29 Manufacturing method of filter, light flux diaphragm device and camera having the filter
US10/630,888 US6952314B2 (en) 2002-07-30 2003-07-30 Method of manufacturing ND filter, and aperture device and camera having ND filter
US10/630,483 US6984044B2 (en) 2002-07-30 2003-07-30 Projection optical system, projection type image display apparatus, and image display system

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101111705B1 (en) 2004-05-14 2012-02-15 니덱 코팔 가부시키가이샤 ND filter and aperture diaphragm apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101111705B1 (en) 2004-05-14 2012-02-15 니덱 코팔 가부시키가이샤 ND filter and aperture diaphragm apparatus

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