JP2018054692A - Optical path length adjustment device, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to simply interchange a glass member on an optical path from a lens mount surface to an imaging surface, and can facilitate adjustment of a flange back length.SOLUTION: An optical path length adjustment device 10 comprises: a fixation member 20 that an image pick-up element 41 is fixed to; a lens mount member 30 that is fixed to the fixation member 20, and has a lens mount surface 31 to which an interchangeable lens 210 is detachably mounted; a glass member 120 that is arranged between the image pick-up element 41 and the lens mount surface 31; and a glass fixation member 150 that is fixed in a state where the glass member 120 is held. The glass fixation member 150 is fixed detachably from outside of a subject side. Thanks to detachment of the glass fixation member 150, the glass member 120 is held by the glass fixation member 150 so as to be replaceable with other glass member 120 different in a refractive index.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical path length adjusting device for adjusting a flange back length of an interchangeable lens type imaging device, and an imaging device such as a digital camera including the optical path length adjusting device.

  In an interchangeable lens digital camera or the like, the flange back length, which is the distance of the optical path from the lens mount surface on which the interchangeable lens is detachably mounted to the imaging surface on which incident light that has passed through the imaging optical system forms an image, is an arbitrary length. It is fixed to. The flange back length is preferably adjusted in accordance with individual differences of the interchangeable lenses and environmental changes.

  Conventionally, in order to change the optical path length of a laser beam from a semiconductor laser element, an optical pickup has been proposed in which an optical path length correcting optical element having a refractive index of 1 or more is interposed in an optical path between a collimator lens and an objective lens. (Patent Document 1).

JP 2000-155972 A

  However, in Patent Document 1, the optical path length is adjusted in the product manufacturing process, and the optical path length cannot be adjusted in the product state after manufacturing.

  Accordingly, the present invention provides an optical path length adjusting device and an imaging device that can easily adjust the flange back length by easily replacing the glass member disposed in the optical path from the lens mount surface to the imaging surface. An object is to provide an apparatus.

  In order to achieve the above object, an optical path length adjusting device according to the present invention includes a fixing member to which an imaging element is fixed, and a lens mount having a lens mounting surface that is fixed to the fixing member and on which an interchangeable lens is detachably mounted. A member, a glass member disposed between the imaging element and the lens mount surface, and a glass fixing member fixed in a state of holding the glass member, the glass fixing member on the subject side The glass member is detachably fixed from the outside, and the glass fixing member is held by the glass fixing member so that the glass member can be replaced with another glass member having a different refractive index by removing the glass fixing member. .

  According to the present invention, since the glass member disposed in the optical path from the lens mount surface to the imaging surface can be easily replaced, it is possible to easily adjust the flange back length.

It is the perspective view which looked at a mode that the interchangeable lens was mounted | worn with the camera main body of the digital camera which is an example of embodiment of an imaging device provided with the optical path length adjusting device of this invention from the front side. (A) is the disassembled perspective view seen from the front side of the optical path length adjustment apparatus, (b) is the disassembled perspective view which looked at the optical path length adjustment apparatus shown to (a) from the back side. It is principal part sectional drawing explaining the example which replaces and incorporates the glass member from which thickness differs with respect to an optical path length adjusting device. It is a perspective view of a glass member. It is the figure which looked at the optical path length adjusting device from the front side of the camera body.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a state in which an interchangeable lens is mounted on a camera body of a digital camera which is an example of an imaging apparatus including an optical path length adjusting device according to the present invention, as viewed from the front side (subject side).

  In the digital camera shown in FIG. 1, an interchangeable lens 210 is detachably attached to a lens mount surface 31 of an optical path length adjusting device 10 provided in a camera body 200.

  2A is an exploded perspective view of the optical path length adjusting device 10 viewed from the front side, and FIG. 2B is an exploded perspective view of the optical path length adjusting device 10 shown in FIG. 2A viewed from the back side. .

  As shown in FIG. 2, the optical path length adjusting device 10 includes a fixing member 20, a lens mount member 30, an image sensor unit 40, and a glass unit 100.

  The fixing member 20 is formed in a cylindrical shape having an opening 21 at the center, and fastening portions 23a to 23d to which the lens mount member 30 is fastened are provided on the front side, and the glass holding member 110 is fastened to the back side. Parts 24a to 24d are provided.

  Further, fastening portions 22 a to 22 c to which the imaging element unit 40 is fastened are provided on the back side of the fixing member 20 so as to protrude to the back side. The aperture 21 has an aperture area that does not obstruct subject light that passes through the imaging optical system of the interchangeable lens 210 and enters the imaging surface 42 of the imaging element 41.

  The lens mount member 30 is formed in an annular shape having an opening 32 at the center, a lens mount surface 31 is provided on the front side, and claw portions 33a to 33c are provided on the inner peripheral portion. Further, screw insertion holes 34 a to 34 d are formed in the lens mount member 30, and unillustrated screws inserted into the screw insertion holes 34 a to 34 d are fastened to fastening portions 23 a to 23 d of the fixing member 20. As a result, the lens mount member 30 is fixed to the fixing member 20. A mount surface (not shown) of the interchangeable lens 210 abuts on the lens mount surface 31. The claw portions 33a to 33c are connected to a claw portion (not shown) of the interchangeable lens 210 with a bayonet.

  The image sensor unit 40 includes an image sensor 41 and an element holder 44 that holds the image sensor 41. The imaging element 41 is configured by a CCD sensor, a CMOS sensor, or the like, and has an imaging surface 42 on which subject light that has passed through the imaging optical system of the interchangeable lens 210 forms an image. The subject light imaged on the imaging surface 42 is subjected to photoelectric conversion. And output as an electrical signal.

  In addition, the imaging element 41 is provided with a contact surface 43 that contacts the elastic member 160 of the glass unit 100 outside the imaging surface 42. Screws 45a to 45c are formed in the element holder 44, and unillustrated screws inserted into the screw insertion holes 45a to 45c are fastened to the fastening portions 22a to 22c of the fixing member 20. Thereby, the image sensor unit 40 is fixed to the fixing member 20.

  The glass unit 100 is disposed between the image sensor 41 and the lens mount member 30 and prevents dust and the like from adhering to the image pickup surface 42 of the image sensor 41. The glass unit 100 includes a glass holding member 110, a glass member 120, a glass fixing member 150, and an elastic member 160.

  The glass holding member 110 has an opening 111 in the center, and on the back side, there are fastening portions 112a to 112d to which the glass fixing member 150 is fastened, and a contact surface 113 with which the contact surface 121 of the glass member 120 abuts. Is provided.

  Further, screw insertion holes 114 a to 114 d are formed in the glass holding member 110, and screws 115 a to 115 d (see FIG. 5) inserted into the screw insertion holes 114 a to 114 d are formed in the fastening portions 24 a to 24 d of the fixing member 20. It is concluded. Thereby, the glass holding member 110 is fixed to the fixing member 20.

  The glass member 120 is composed of one or a plurality of sheets. A contact surface 121 that contacts the contact surface 113 of the glass holding member 110 is provided on the front side, and a contact surface 152 of the glass fixing member 150 is provided on the back side. The contact surface 122 which contacts is provided. The contact surface 122 is formed by an inclined surface (see FIG. 3) having a C-chamfered portion between the rear side end surface and the outer peripheral surface of the glass member 120, and the contact surface 152 is also formed by an inclined surface corresponding to the contact surface 122.

  The glass fixing member 150 has an opening 151 at the center, a contact surface 152 that contacts the contact surface 122 of the glass member 120 is provided on the front side, and a contact surface 162 of the elastic member 160 on the back side. A contact surface 153 that abuts is provided.

  The contact surface 152 and the contact surface 122 of the glass member 120 that is in contact with the contact surface 152 need to be in close contact over the entire circumference in order to prevent dust and the like from adhering to the imaging surface 42 of the imaging element 41. For this reason, in the present embodiment, the glass fixing member 150 uses an elastic material such as a flexible rubber material and is overcharged to bring the contact surfaces 152 and 122 into close contact with each other.

  Further, screw insertion holes 154a to 154d are formed in the glass fixing member 150, and screws (not shown) inserted into the screw insertion holes 154a to 154d are fastened to the fastening portions 112a to 112d of the glass holding member 110. Thereby, the glass fixing member 150 is fixed to the glass holding member 110.

  The elastic member 160 is provided with a contact surface 161 that contacts the contact surface 43 of the imaging element 41 on the back side, and a contact surface 162 that contacts the contact surface 153 of the glass fixing member 150 on the front side. As described above, the contact surface 161 and the contact surface 43 of the image sensor 41 need to be in close contact with each other over the entire circumference. Therefore, the elastic member 160 is overcharged so that the contact surfaces 161 and 43 are in close contact with each other. . The contact surface 162 is fixed to the contact surface 153 of the glass fixing member 150 with a double-sided tape (not shown).

  Thus, in the present embodiment, a structure in which the space between the image sensor 41 and the glass member 120 is sealed by the glass member 120, the glass fixing member 150, the elastic member 160, and the image sensor 41 is employed. . Thereby, it is possible to prevent dust and the like from entering the imaging surface 42 of the imaging element 41.

  Here, in the present embodiment, the glass member 120 (hereinafter, referred to as glass members 120a to 120c) having different thicknesses in the optical axis direction can be replaced with the optical path length adjusting device 10 and incorporated.

  3A is a cross-sectional view of the main part when a glass member 120a having a standard thickness of 1.0 mm is incorporated, and FIG. 3B is a glass member 120b having a thickness of 0.7 mm which is 0.3 mm thinner than the thickness of the glass member 120a. It is principal part sectional drawing when incorporating. FIG.3 (c) is principal part sectional drawing when incorporating the glass member 120c of thickness 1.3mm thick 0.3mm thicker than the thickness of the glass member 120a. FIG. 4 is a perspective view of the glass member 120.

  As shown in FIG. 3, glass members 120a to 120c having different thicknesses in the optical axis direction have an outer peripheral surface 123 having the same dimension A parallel to the optical axis. Therefore, when the contact surface 122 made of an inclined surface provided on the entire circumference of the glass member 120a is C chamfered and is C0.5, the contact surface 122 of the glass member 120b is C0.2, and the contact surface 122 of the glass member 120c is C0.8. That is, regardless of the thickness of the glass member 120, the contact surface 122 and the contact surface 152 of the glass fixing member 150 can be in close contact with each other, and the sealing around the imaging surface 42 of the imaging element 41 can be achieved. No effect.

  FIG. 5 is a view of the optical path length adjusting device 10 as viewed from the front side of the camera body 200. In the state shown in FIG. 5, the glass unit 100 of the optical path length adjusting device 10 is removed from the camera body 200 by removing the screws 115 a to 115 d fastened to the fastening portions 24 a to 24 d of the fixing member 20 from the outside on the subject side. Is possible. By removing the glass unit 100 of the optical path length adjusting device 10, dust can be removed even if dust or the like adheres to the imaging surface 42 of the imaging element 41.

  Further, the glass fixing member 150 can be removed from the glass unit 100 by removing screws (not shown) fastened to the fastening portions 112 a to 112 d of the glass holding member 110 in a state where the glass unit 100 is removed. Thereby, it becomes possible to easily remove the glass member 120 from the glass fixing member 150 and replace the glass member 120.

  The change in the optical path length due to the replacement with the glass member 120 having a different thickness in the optical axis direction can be represented by the change in the optical path length = the change in the thickness × (1-1 / the refractive index of the glass). That is, by changing the glass thickness, the optical path length can be changed, and the flange back length can be adjusted.

  For example, if the refractive index of the glass member 120 is 1.5 and the thickness is changed by 0.3 mm, the optical path length is increased by 0.1 mm according to the above formula, and therefore the flange back length is reduced by 0.1 mm in terms of air. It becomes possible to do. Further, when the refractive index of the glass member 120 is 1.5 and the thickness is changed by 0.3 mm, the optical path length is shortened by 0.1 mm according to the above formula, so the flange back length is increased by 0.1 mm in terms of air. It becomes possible to do.

  As described above, in the present embodiment, the glass member 120 disposed in the optical path from the lens mount surface 31 to the imaging surface 42 can be easily replaced with another glass member 120 having a different thickness. Adjustment can be performed easily.

  In this embodiment, the refractive index is changed by changing the thickness of the glass member 120. However, the refractive index may be changed with the thickness of different glass members 120 being constant. For example, if the refractive index of the glass member 120 is increased from 1.5 to 1.8 and the thickness of the glass member 120 is constant at 1.0 mm, the optical path length is increased by 0.111 mm from the above formula. The length can be reduced by 0.111 mm in terms of air.

  If the refractive index of the glass member 120 is lowered from 1.5 to 1.2 and the thickness of the glass member 120 is constant at 1.0 mm, the optical path length is shortened by 0.167 mm according to the above formula. The length can be increased by 0.167 mm in terms of air. Thus, the flange back length can be adjusted by changing the refractive index of the glass member 120.

  Furthermore, the following effect is acquired by changing into the glass member 120 from which optical characteristics other than refractive index differ.

  That is, it is possible to adjust the amount of light condensed on the imaging surface 42 of the imaging element 41 by exchanging with the glass member 120 having a different transmittance, and by exchanging with the glass member 120 having polarization characteristics, It is possible to suppress the reflection of light. By exchanging with the glass member 120 that does not have infrared light cut characteristics, an image including infrared light can be taken.

  The configuration of the present invention is not limited to that exemplified in the above embodiment, and the material, shape, dimensions, form, number, arrangement location, and the like can be changed as appropriate without departing from the scope of the present invention. It is.

20 fixing member 30 lens mounting member 31 lens mounting surface 41 imaging element 120 glass member 150 glass fixing member 210 interchangeable lens

Claims (8)

A fixing member to which the image sensor is fixed;
A lens mount member fixed to the fixing member and having a lens mount surface to which an interchangeable lens is detachably mounted;
A glass member disposed between the imaging element and the lens mount surface;
A glass fixing member fixed in a state of holding the glass member,
The glass fixing member is detachably fixed from the outside on the subject side,
The glass member is held by the glass fixing member so that the glass member can be replaced with another glass member having a different refractive index by removing the glass fixing member.   The optical path length adjusting device according to claim 1, wherein a space between the image sensor and the glass member is sealed.   The optical path length adjusting device according to claim 1, wherein the glass member and the other glass member have different thicknesses in the optical axis direction.   In the glass member, an inclined surface chamfered between an end surface in the optical axis direction and an outer peripheral surface parallel to the optical axis is in contact with the inclined surface provided in the glass fixing member over the entire circumference, and the glass member and the other The optical path length adjusting device according to claim 3, wherein the glass member has the same length in the optical axis direction of the outer peripheral surface.   The optical path length adjusting device according to claim 1, wherein the glass member and the other glass member have a constant thickness in the optical axis direction.   The optical path length adjusting device according to any one of claims 1 to 5, wherein the glass member and the other glass member have different optical characteristics.   The optical path length adjusting device according to any one of claims 1 to 5, wherein the glass member and the other glass member have different transmittances.   An imaging apparatus comprising the optical path length adjustment device according to claim 1.

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