JP2007041121A - Prism holding structure and lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain prism holding structure capable of surely holding a rectangular prism without using an adhesive, and at least mitigating the degradation of optical performance caused by positional deviation between the rectangular prism and a holding member caused by the change of operating environment. <P>SOLUTION: In the prism holding structure for holding the rectangular prism 40 in such a state that it is accurately positioned by the holding member 20, the holding member is equipped with: an insertion port 220; a receiving surface 241 positioned nearly perpendicularly to the opening surface 221 of the insertion port; a supporting part 263 positioned in the vicinity of the insertion port; and a repulsive energizing part 252 exerting repulsive force in the direction of the receiving surface and the supporting part. By repulsively energizing the inclined surface of the rectangular prism where a light entering surface 41, a light emitting surface 42 and the inclined surface 43 cross each other to form a right triangle by the repulsive energizing part, either the light entering surface or the light emitting surface abuts on the receiving surface, and the side edge part of the other abuts on the supporting part, whereby the rectangular prism is held by the holding member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel prism holding structure and a lens barrel. More specifically, the present invention relates to a technique for alleviating deterioration in optical performance due to a displacement of a right-angle prism due to a change in use environment (temperature, humidity, etc.).

  In an optical system using a right-angle prism, the displacement of the right-angle prism caused by the difference in the coefficient of thermal expansion between the right-angle prism and the holding member that holds it due to changes in the usage environment (temperature, humidity, etc.) It is a great concern to alleviate or avoid misalignment of the right-angle prism due to changes in the usage environment, because it causes misalignment and causes a significant decrease in optical performance.

  The right-angle prism has an outer shape constituted by two planes whose shapes are perpendicular to each other, a slope connecting the two planes, and two side surfaces located on the side surfaces of the portion surrounded by the three planes. For this reason, for example, there are few portions that can be held between both sides (the side surfaces can only be pressed from both sides), and there is a problem that positioning in a direction orthogonal to the optical axis is difficult.

  For example, a structure disclosed in Patent Document 1 has been proposed as a technique for mitigating or avoiding misalignment of an optical component due to a change in use environment.

  FIG. 5 shows a simplified structure when the structure shown in Patent Document 1 is applied to the holding of a right-angle prism.

  In FIG. 5, a is a right-angle prism, and b is a holding member for holding the right-angle prism. The two orthogonal surfaces c and d of the right-angle prism a are in contact with the two orthogonal surfaces e and f of the holding member b, and the plane c of the right-angle prism a is fixed to the holding surface e of the holding member b by an adhesive. Has been. The holding surface f of the holding member b is constituted by small protrusions h and h protruding upward from the bottom surface part g, and the small protrusions h and h are formed thin so as to have a bending elasticity.

  When the usage environment (temperature, humidity, etc.) changes, stress is generated due to the difference in the coefficient of thermal expansion between the right-angle prism a and the holding member b, and the stress is displaced relative to the right-angle prism a and the holding member b. However, in the holding structure shown in FIG. 5, the stress is absorbed as a force that deforms the small protrusions h and h, so that the relative positional deviation between the right-angle prism a and the holding member b is reduced. Will not occur.

  Moreover, like the holding structure shown in Patent Document 2, the holding member is fixed to the fixing member via a rigid body such as a hard ball between the holding member that holds the optical element and the fixing member that fixes the holding member. In other words, by using a configuration in which no adhesive is directly interposed between the holding member and the fixing member, there is also a technique that prevents relative displacement between the optical element and the fixing member due to curing shrinkage or thermal expansion of the adhesive.

JP 2005-43434 A JP 2005-38493 A

  By the way, in the structure disclosed by the above-mentioned patent document 1, the holding member b itself does not have a fixing means for fixing the right-angle prism a, and the fixing between the right-angle prism a and the holding member b is performed by an adhesive. Yes. However, since the adhesive shrinks at the time of curing, the relative position between the right-angle prism a and the holding member b is shifted from the desired one after the bonding. In general, the thermal linear expansion coefficient of the adhesive does not match the thermal linear expansion coefficient of the right-angle prism a made of optical glass or the like, or the holding member b formed of resin or metal. Therefore, when the usage environment (temperature, humidity, etc.) changes, the dimensions of the right-angle prism a, the holding member b, and the adhesive change, and the occurrence of relative displacement between the right-angle prism a and the holding member b is avoided. Cannot be performed, causing deterioration of optical performance. Further, in order to suppress the deterioration of the optical performance even if the relative positional deviation between the right-angle prism a and the holding member b occurs, it is necessary to reduce the position sensitivity of the right-angle prism a in the optical system. This leads to a reduction in design freedom. Furthermore, since an adhesive is used for the assembly, an increase in assembly cost due to the time of application and curing of the adhesive, and the possibility of adverse effects on the right-angle prism a by the gas emitted from the adhesive cannot be denied.

  In the structure shown in Patent Document 2, an adhesive is not necessarily required, but a rigid body is required for fixing between the holding member (or the optical element) that holds the optical element and the fixing member. This has led to increased parts and assembly costs due to hindrance and an increase in the number of parts.

  Therefore, in view of the above circumstances, the present invention reliably holds a right-angle prism without using an adhesive, and deteriorates optical performance due to misalignment between the right-angle prism and the holding member due to a change in use environment. It is an object to at least mitigate.

  In the prism holding structure of the present invention, in order to solve the above-described problem, the holding member for holding the right-angle prism includes an insertion port, a receiving surface positioned substantially perpendicular to the opening surface of the insertion port, and the insertion port. A right angle where the light incident surface, the light emission surface, and the inclined surface intersect with each other so as to form a right triangle, comprising a support portion located in the vicinity and a resilient urging portion that exerts a resilient force in the direction of the receiving surface and the support portion. The elastic biasing portion elastically biases the slope of the prism, and one of the light incident surface and the light emitting surface is in contact with the receiving surface, and the other side edge is in contact with the support portion. Thus, the right-angle prism is held by the holding member.

  Therefore, in the prism holding structure of the present invention, one of the two surfaces of the right-angle prism that intersect each other at right angles by the elastic biasing portion is in contact with the receiving surface, and the other surface is in elastic contact with the support portion. The right-angle prism is held by the holding member without using an adhesive.

  The lens barrel of the present invention holds the right-angle prism by the right-angle prism holding structure of the present invention.

  The prism holding structure of the present invention is a prism holding structure that holds a right-angle prism in a state where the prism holding structure is accurately positioned, and the holding member is substantially perpendicular to the insertion port and the opening surface of the insertion port. A receiving surface that is positioned, a support portion that is positioned in the vicinity of the insertion port, and a resilient urging portion that exerts a resilient force in the direction of the receiving surface and the supporting portion, and a light incident surface, a light emitting surface, and a slope are provided. The elastic biasing portion elastically biases the inclined surface of the right-angled prism that intersects to form a right triangle so that one of the light incident surface and the light emitting surface is in contact with the receiving surface, and the other side. The edge portion is in contact with the support portion, whereby the right-angle prism is held by the holding member.

  Therefore, in the prism holding structure of the present invention, the right-angle prism can be held on the holding member without using an adhesive. Also, when a difference occurs in the dimensions between the right angle prism and the holding member due to changes in the usage environment, the difference in the above dimensions is absorbed by the change in the elastic force of the elastic biasing portion. The holding is continued in a state in which no rattling occurs between the members and the displacement of the relative position between the right-angle prism and the holding member is reduced.

  In the invention described in claim 2, since the elastic biasing portion elastically contacts the inclined surface outside the optically effective surface of the inclined surface, the optical performance is improved by the elastic contact of the elastic biasing portion with the inclined surface. There is no decline.

  According to a third aspect of the present invention, the support portion includes an elastic arm having flexural elasticity and an engaging claw formed at a front end of the elastic arm, and the engaging claw is the light incident surface or the light exiting surface. Since it engages with the side edge of the surface outside the optical effective surface of the surface, when the right angle prism reaches a predetermined position simply by inserting the right angle prism into the holding member with the elastic arm bent. Further, since the bending of the elastic arm returns to the original state and the engaging claw engages with the right-angle prism, the holding work of the right-angle prism to the holding member is easy. Further, since the engaging claw engages with the side edge portion of the right-side prism on the light incident surface or light exit surface outside the optically effective surface, the optical performance is not deteriorated by the engagement of the engaging claw.

  In the invention described in claim 4, since the receiving surface, the support portion, and the elastic urging portion are formed integrally with the holding member, the number of components is the smallest, so the cost can be reduced. It can be reduced and parts management becomes easy.

  In the invention described in claims 5 and 7, since the lens holding frame is integrally formed on the front side of the insertion port, the right-angle prism and the lens disposed immediately before the lens are accurately positioned. The two optical components can be held by one holding member, which contributes to cost reduction.

  The lens barrel of the present invention is a lens barrel including a main lens barrel that holds a fixed lens group and / or a movable lens group, and a prism holding member that is fixed to the light incident side of the main lens barrel, The prism holding member includes an insertion port, a receiving surface positioned substantially at right angles to the opening surface of the insertion port, a support portion positioned in the vicinity of the insertion port, and a resilient force toward the receiving surface and the support portion. A bullet urging portion that exerts a force, and the bullet urging portion elastically urges the inclined surface of the right-angle prism in which the light incident surface, the light emitting surface, and the inclined surface intersect to form a right triangle. One of the light incident surface and the light exit surface is in contact with the receiving surface, and the other side edge is in contact with the support portion, whereby the right-angle prism is held by the holding member. To do.

  Therefore, in the lens barrel of the present invention, the right-angle prism can be held on the holding member without using an adhesive. Also, when a difference occurs in the dimensions between the right angle prism and the holding member due to changes in the usage environment, the difference in the above dimensions is absorbed by the change in the elastic force of the elastic biasing portion. The holding is continued in a state in which no rattling occurs between the members and the displacement of the relative position between the right-angle prism and the holding member is reduced.

  The best mode for carrying out the prism holding structure and the lens barrel of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of a lens barrel of the present invention.

  The lens barrel 1 is for assembling a four-group inner focus type zoom lens. The lens barrel 1 has a substantially rectangular tube-shaped main barrel 10 and a front lens barrel (prism holding) attached to the front end of the main barrel 10. Member) 20 and a rear unit 30 attached to close the rear end of the main barrel 10.

  Two movable lens frames 11 and 12 are supported in the main barrel 10 so as to be movable in the axial direction, the second movable lens frame GR2 is supported on the front movable lens frame 11, and the rear movable lens frame 12 is supported. The fourth lens group GR4 is supported. A third lens group (not shown) fixed in the axial direction is supported in the main barrel 10 so as to be positioned between the two movable lens groups GR2 and GR4. The rear unit 30 supports an image pickup device such as a CCD (Charge Coupled Device) (not shown).

  The front lens barrel 20 supports a first lens group GR1 including a right-angle prism. By attaching the front lens barrel 20 to the front end of the main lens barrel 10, the optical axis is changed in the first lens group GR1. A four-group inner focus type zoom lens that can be bent 90 degrees is assembled.

  The prism holding structure of the present invention is applied to the front lens barrel 20. Details of the prism holding structure will be described with reference to FIGS.

  Here, the front lens barrel 20 is a holding member that holds the right-angle prism 40. In this embodiment, the first lens 50 constituting the first lens group GR1 is also held together with the right-angle prism 40.

  The front lens barrel 20 is formed in a container shape having a storage space 210 that is slightly larger than the right-angle prism 40 and includes a large insertion port 220 at the front end. The storage space 210 includes a circular frame portion 230 that defines the insertion port 220, and a bottom surface that extends rearward from a position near the lower end of the frame portion 230 and is substantially perpendicular to the opening surface 221 of the insertion port 220. Surrounded by a wall 240, a rear wall 250 extending obliquely forward and upward from the rear end of the bottom wall 240 and connected to a portion near the upper end of the frame portion 230, and side walls 260 and 260 covering the side surfaces of the space 210. Formed. In addition, attachment pieces 270 and 270 protrude laterally from the lower ends of the side walls 260 and 260. The attachment pieces 270 and 270 are formed with screw insertion holes 271 and 271 and positioning holes 272 and 272, respectively.

  The frame 230 has an annular shape with a short axis extending in the front-rear direction, and a receiving edge 231 facing forward is formed at a position slightly rearward from the front end, and a portion 232 on the front side of the receiving edge 231 is caulked. It is considered a rim.

  An upper surface 241 of the bottom wall 240 is a receiving surface as a reference surface, and a light transmitting hole 242 is formed in the bottom wall 240 except for the peripheral portion.

  Inverted U-shaped (upper part) or U-shaped (lower part) slits 251, 251,... Extending from the upper and lower left and right ends of the rear wall 250 toward the center along the side edges, respectively. , And the portions 252, 252,... Surrounded by these slits 251, 251,... Serve as bullets and are pressed against the front surface of the tip of the bullets 252, 252. Projections 253, 253,... Are formed. And the above-mentioned bullet-emitting pieces 252, 252,...

  The side walls 260, 260 are formed with two parallel slits 261, 261,... Extending rearward from the front end thereof, and between the two parallel slits 261, 261 and 261, 261. The portions 262 and 262 are elastic arms, and engaging claws 263 and 263 projecting toward each other are formed at the front ends of the elastic arms 262 and 262. The front surfaces of the engaging claws 263 and 263 are inclined surfaces 263a. H.263a.

  The front lens barrel 20 described above has a rigidity and a resilient piece 252, 252,..., An elastic arm 262, and a degree necessary to obtain surface accuracy necessary for supporting the right angle prism with a predetermined positional accuracy. The 262 has a degree of elasticity having a moderate elasticity, and is formed of a material suitable for integrally forming the above-described parts. For example, it is formed of a synthetic resin such as PC (polycarbonate). When the front lens barrel 20 is formed by a PC, a filler material such as glass fiber is mixed in order to provide rigidity that does not impair the elasticity of the elastic pieces 252, 252,... And the elastic arms 262 262. It is also good to do. As a filler material, for example, when glass fiber is mixed, it is appropriate that the weight ratio of glass fiber to PC is 20 to 30%.

  Next, the holding of the right-angle prism 40 to the front lens barrel (holding member) 20 will be described. The right angle prism 40 is inserted into the front lens barrel 20 from the front insertion slot 220 with the light incident surface 41 facing forward, the light exit surface 42 facing downward, and the inclined surface 43 facing obliquely rearward and upward. Go. Then, first, the corner portion where the side surfaces 44, 44 of the right-angle prism 40 and the inclined surface 43 intersect with each other comes into contact with the inclined surfaces 263a, 263a of the engaging claws 263, 263 of the front side barrel 20, and the inclined surfaces 263a, 263a. Since the elastic arms 262 and 262 are bent outward, the right-angle prism 40 is inserted into the front lens barrel 20 with the side surfaces 44 and 44 and the tips of the engaging claws 263 and 263 being in contact with each other. . And when the right-angle prism 40 comes a little before it is completely inserted into the front lens barrel 20, the pressing protrusions 253, 253, ... of the elastic pieces 252, 252, ... formed on the rear wall 250. Comes into contact with the inclined surface 43 of the right-angle prism 40. From this state, when the right-angle prism 40 is further inserted into the front lens barrel 20, the rear surfaces of the engaging claws 263, 263 of the front lens barrel 20 come to a position corresponding to the light incident surface 41 of the right-angle prism 40. The elastic arms 262 and 262 that have been bent outward return to the original state, and the engaging claws 263 and 263 engage with the side edges of the light incident surface of the right-angle prism 40. At the same time, the light exit surface 42 of the right-angle prism 40 comes into contact with the receiving surface 241 of the front lens barrel 20. During this time, the inclined surface 43 of the right-angle prism 40 presses the pressing protrusions 253, 253,... Diagonally upward, so that the elastic pieces 252, 252,. . Therefore, the elastic force is stored in the elastic pieces 252, 252,..., And the elastic force presses the inclined surface 43 of the right-angle prism 40 through the pressing protrusions 253, 253,. The surface 41 is in elastic contact with the engaging claws 263 and 263, and the light exit surface 42 is in elastic contact with the receiving surface 241. Therefore, if the engaging claws 263 and 263 and the receiving surface 241 are formed with a predetermined positional accuracy, the right-angle prism 40 is held in a state of being accurately positioned on the front lens barrel 20. In addition, the positions where the pressing projections 253, 253,... And the engaging claws 263, 263 of the front lens barrel 20 abut are outside the inclined surface 43 of the right-angle prism 40 and the optically effective surface of the light incident surface 41, respectively. It is preferable.

  If a dimensional difference occurs between the right-angle prism 40 and the front lens barrel 20 due to a change in use environment, for example, if the front lens barrel 20 becomes larger, the impact of the front lens barrel 20 is reduced. The front ends of the elastic pieces 252, 252,... Are displaced substantially forward by the elastic force stored in the pieces 252, 252,. Further, the light exit surface 42 remains in contact with the joint claws 263, 263 and the receiving surface 241, and the two surfaces 41, 42 are positioned by the engaging claws 263, 263 and the receiving surface 241. Retained. On the other hand, when the front lens barrel 20 becomes smaller, the deflection of the elastic pieces 252, 252,... 40, the two surfaces 41 and 42 are held at positions defined by the engaging claws 263 and 263 and the receiving surface 241.

  The front lens barrel 20 according to the above embodiment can also hold the first lens 50. The first lens 50 is inserted into the frame 230 of the front lens barrel 20 after the right-angle prism 40 is held by the front lens barrel 20. When the rear peripheral edge of the first lens 50 comes into contact with the receiving edge 231, the first lens 50 is moved to the front mirror by caulking the caulking edge 232 over the front peripheral edge of the first lens 50. The cylinder 20 is held.

  As described above, the front lens barrel 20 holding the right-angle prism 40 and the first lens 50, that is, the first lens group GR1, is positioned in the positioning holes 272, 272 of the mounting pieces 270, 270 in the front end of the main lens barrel 10. The positioning projections 13 and 13 formed on the first and second projections 13 and 13 are engaged and positioned, and screws (not shown) are inserted through the screw insertion holes 271 and 271 of the attachment pieces 270 and 270 and formed at the front end of the main barrel 10. Thus, the front lens barrel 20 is attached to the front end portion of the main lens barrel 10 to complete the lens barrel 1.

  In the front lens barrel 20, it is desirable that the receiving surface 241, the engaging claws 263 and 263 as the support portions, and the mounting pieces 270 and 270 are positioned as close as possible. As a result, the X-direction distance between the mounting pieces 270 and 270 and the engaging claws 263 and 263 and the Y-direction distance between the mounting pieces 270 and 270 and the receiving surface 241 are not easily affected by dimensional changes due to temperature changes. Therefore, the relative displacement between the right angle prism 40 and the first lens 50 held in the front lens barrel 20 and the optical elements such as the second lens group GR2 held in the main lens barrel 10 is alleviated. can do.

  It should be noted that the specific shapes, structures, or numbers of the respective parts shown in the above-described embodiments are merely examples of the implementation performed in carrying out the present invention, and are limited to those described above. is not. For example, the bullet urging portion is not limited to the bullet piece 252 described above, and even if it is the bullet piece 252, its formation position and number are not limited to those described above. In addition, the support portion is not limited to the above-described engagement claw 263. Even if the engagement claw 263 is used, the formation location and number of the support portions are not limited to those described above. , Two on one side and one on the other.

It is a disassembled perspective view which shows embodiment of the lens-barrel of this invention. FIG. 3 and FIG. 4 show an embodiment of the prism holding structure of the present invention, which is an exploded perspective view. It is a perspective view of a holding member. It is sectional drawing of the principal part. It is a schematic perspective view which shows an example of the conventional prism holding structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lens barrel, 10 ... Main lens barrel, 20 ... Front side lens barrel (prism holding member), 220 ... Insertion port, 221 ... Opening surface, 230 ... Frame part (lens holding frame), 241 ... Reception surface, 252 ... Bullet piece (ballistic biasing part), 262 (elastic arm), 263 (engagement claw) ... support part, 40 ... right angle prism, 41 ... light incident surface, 42 ... light exit surface, 43 ... slope, GR2 ... first 2 lens group (movable lens group), GR4 ... 4th lens group (movable lens group)

Claims (7)

A prism holding structure that holds a right-angle prism in a state of being accurately positioned on the holding member,
The holding member includes an insertion port, a receiving surface positioned substantially at right angles to the opening surface of the insertion port, a support portion positioned in the vicinity of the insertion port, and a resilient force in the direction of the receiving surface and the support portion. A bullet energizing section that exerts
The bullet urging portion elastically biases the slope of the right-angle prism where the light entrance surface, the light exit surface, and the slope intersect so as to form a right triangle, and one of the light entrance surface and the light exit surface is the above. A prism holding structure, wherein the prism is held against the receiving surface, and the other side edge is brought into contact with the support, whereby the right-angle prism is held by the holding member. The prism holding structure according to claim 1, wherein the elastic urging portion elastically contacts the inclined surface outside the optically effective surface of the inclined surface. The support portion includes an elastic arm having flexural elasticity and an engaging claw formed at a front end of the elastic arm, and the engaging claw is located on the side of the surface outside the optically effective surface of the light incident surface or the light exit surface. The prism holding structure according to claim 1, wherein the prism holding structure is engaged with an edge portion. The prism holding structure according to claim 1, wherein the receiving surface, the support portion, and the bullet urging portion are formed integrally with a holding member. The prism holding structure according to claim 1, wherein a lens holding frame is integrally formed on the front side of the insertion port. A lens barrel comprising a main lens barrel that holds a fixed lens group and / or a movable lens group, and a prism holding member that is fixed to the light incident side of the main lens barrel,
The prism holding member includes an insertion port, a receiving surface positioned substantially at right angles to the opening surface of the insertion port, a support portion positioned in the vicinity of the insertion port, and a resilient force toward the receiving surface and the support portion. A bullet energizing section that exerts power,
The bullet urging portion elastically biases the slope of the right-angle prism where the light entrance surface, the light exit surface, and the slope intersect so as to form a right triangle, and one of the light entrance surface and the light exit surface is the above. A lens barrel, wherein the lens barrel is in contact with the receiving surface, and the other side edge is in contact with the support portion, whereby the right-angle prism is held by the holding member. The lens barrel according to claim 6, wherein a lens holding frame is integrally formed on the front side of the insertion opening.

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