Image pickup apparatus
First Claim
1. An image pickup apparatus comprising an exposure control mechanism for adjusting a quantity of light flux entering a shooting lens system, said exposure control mechanism comprising:
- a diaphragm made up of diaphragm blades movable in a plane perpendicular to an optical axis in opposite directions to define a diaphragm aperture; and
an ND filter formed by placing a plurality of filter plates in adjacently overlapped relation, said filter plates having the same transmittance but being different in size, wherein when said diaphragm blades are displaced from an aperture open state in a direction to restrict the quantity of the light flux, an aperture area is restricted by said diaphragm blades from the open state to a predetermined aperture area, and thereafter said ND filter is advanced into said diaphragm aperture successively from a combination of said ND filter elements having the highest transmittance while the predetermined aperture area is maintained.
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Accused Products
Abstract
The invention concerns with an exposure control mechanism for use in an image pickup apparatus in which a diaphragm aperture formed by a plurality of diaphragm blades moving straightforward in opposite directions is covered by an ND filter, and intends to prevent deterioration of image quality caused by diffraction even in an image pickup device having a small picture size and a short pixel pitch. The image pickup apparatus comprises an exposure control mechanism for adjusting the quantity of light flux entering a shooting lens system. The exposure control mechanism comprises a diaphragm made up of diaphragm blades movable on a plane perpendicular to an optical axis in opposite directions to define a diaphragm aperture, and an ND filter made up of at least two ND filter elements having different transmittances. When the diaphragm blades are displaced from an aperture open state in a direction to restrict the quantity of transmitting light, an aperture area is restricted by the diaphragm blades from the open state to a predetermined aperture area, and thereafter the ND filter is advanced into the diaphragm aperture successively from one of the ND filter elements having the highest transmittance while the predetermined aperture area is maintained.
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Citations
26 Claims
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1. An image pickup apparatus comprising an exposure control mechanism for adjusting a quantity of light flux entering a shooting lens system, said exposure control mechanism comprising:
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a diaphragm made up of diaphragm blades movable in a plane perpendicular to an optical axis in opposite directions to define a diaphragm aperture; and
an ND filter formed by placing a plurality of filter plates in adjacently overlapped relation, said filter plates having the same transmittance but being different in size, wherein when said diaphragm blades are displaced from an aperture open state in a direction to restrict the quantity of the light flux, an aperture area is restricted by said diaphragm blades from the open state to a predetermined aperture area, and thereafter said ND filter is advanced into said diaphragm aperture successively from a combination of said ND filter elements having the highest transmittance while the predetermined aperture area is maintained. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An exposure control mechanism for an image pickup apparatus having an optical axis, said mechanism comprising:
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an upper diaphragm element movable in a first direction in a plane perpendicular to the optical axis;
a lower diaphragm element movable in a second direction, opposite to the first direction, in the plane perpendicular to the optical axis;
an ND filter unit movable in the second direction in the plane perpendicular to the optical axis, said ND filter element comprising at least two ND filter elements of different transmittances, wherein said ND filter unit comprises a plurality of filter elements, each of said plurality of filter elements having a substantially equal transmittance. - View Dependent Claims (8, 9, 10, 11, 12)
a first driving unit engaged to said upper and lower diaphragm elements.
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9. An exposure control mechanism according to claim 8, further comprising:
a second driving unit engaged to said ND filter unit.
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10. An exposure control mechanism according to claim 7, further comprising:
a driving unit engaged to said upper and lower diaphragm elements, and to said ND filter unit.
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11. An exposure control mechanism according to claim 7, wherein said lower diaphragm element is positioned between said ND filter unit and said upper diaphragm element.
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12. An exposure control mechanism according to claim 7, wherein said ND filter unit comprises:
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a first ND filter element having a minimum height;
a second ND filter element having a maximum height; and
a plurality of remaining ND filter elements positioned between said first and second filter elements and having heights between the minimum and maximum heights, wherein the height of each of said remaining filter elements is greater than the height of each filter element positioned closer to said first element.
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13. An exposure control mechanism for an image pickup apparatus having an optical axis, said mechanism comprising:
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an upper diaphragm element movable in a first direction in a plane perpendicular to the optical axis;
a lower diaphragm element movable in a second direction, opposite to the first direction, in the plane perpendicular to the optical axis;
an ND filter unit movable in the second direction in the plane perpendicular to the optical axis, said ND filter element comprising at least two ND filter elements of different transmittances, wherein each of said plurality of filter elements has a different transmittance, and wherein said ND filter unit comprises;
a first filter element having a maximum transmittance value;
a second filter element having a minimum transmittance value; and
a plurality of remaining ND filter elements positioned between said first and second filter elements and having transmittance values between the minimum and maximum transmittance values, wherein the transmittance value of each of said remaining filter elements is greater than the transmittance value of each filter element positioned closer to said second filter element. - View Dependent Claims (14, 15, 16, 17)
a first driving unit engaged to said upper and lower diaphragm elements.
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15. An exposure control mechanism according to claim 14, further comprising:
a second driving unit engaged to said ND filter unit.
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16. An exposure control mechanism according to claim 13, further comprising:
a driving unit engaged to said upper and lower diaphragm elements, and to said ND filter unit.
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17. An exposure control mechanism according to claim 13, wherein said lower diaphragm element is positioned between said ND filter unit and said upper diaphragm element.
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18. An ND filter unit comprising:
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an ND filter plate including a plurality of filter elements, said filter plate comprising;
a first filter element having a maximum transmittance value;
a second filter element having a minimum transmittance value; and
a plurality of remaining ND filter elements positioned between said first and second filter elements and having transmittance values between the minimum and maximum transmittance values, wherein the transmittance value of each of said remaining filter elements is greater than the transmittance value of each filter element positioned closer to said second filter element. - View Dependent Claims (19, 20, 21)
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21. An ND filter unit according to claim 20, wherein a relationship between the first height and the second height satisfies the following:
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22. An ND filter unit, comprising:
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a plurality of substantially planar filter elements positioned in adjacently overlapped fashion, said elements having substantially equivalent transmittance values but having different heights, wherein said plurality of overlapped filter elements comprises;
a first ND filter element having a minimum height;
a second ND filter element having a maximum height; and
a plurality of remaining ND filter elements positioned between said first and second filter elements and having heights between the minimum and maximum heights, wherein the height of each of said remaining filter elements is greater than the height of each filter element positioned closer to said first element. - View Dependent Claims (23)
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24. An ND filter unit, comprising:
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a plurality of substantially planar filter plates positioned in adjacently overlapped fashion, each filter plate including a plurality of filter elements, wherein the plurality of planar filter plates comprises;
a first ND filter plate having a first height; and
a second ND filter plate having a second height, wherein said plurality of filter elements each have a different transmittance value and a different height. - View Dependent Claims (25, 26)
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Specification