JP2010262009A - Optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate attaching an optical device thinner than a conventional one, to a lens frame or the like. <P>SOLUTION: The optical device has an optical functional face on an incident face and on an exit face, and includes a rectangular optical effective region in the optical functional face when seen along the direction of the optical axis. A vertex of the optical effective region is located close to the outer circumference of the optical device, a length ratio of the diagonal line in the optical effective region in the incident face side to the diagonal line in the optical effective region in the exit face side is substantially 1. The device includes, in an outer circumference of the optical effective region, a holding unit to hold the optical device or a positioning unit to determine the position of the optical device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical element used in an optical system such as an imaging apparatus.

  2. Description of the Related Art Conventionally, optical elements used in optical systems, mainly imaging devices, have a shape in which the outer surface is centered after the optical surface has been finished in advance by polishing (grinding) or pressing. There are many. Further, an optical element having a shape that does not require centering by restricting the outer peripheral portion during press working is also used.

  These optical elements are often attached to a lens frame and used. Conventionally, when an optical element is attached to a lens frame, a side surface formed by centering or outer periphery regulation is used. In addition, many methods have been proposed in which the shape of the optical element is devised for improving positioning accuracy and ease of mounting, reducing the radial dimension, and the like.

  For example, Patent Document 1 discloses a shape of an optical element in which an outer peripheral portion having three positioning portions at an equal distance from the optical axis is a free-form surface shape in an optical element having a flange portion outside the optical function surface. ing.

  Further, in Patent Document 2, in an optical element that has an optical function surface and an outer peripheral surface, and is held with high surface accuracy of the optical function surface, There is disclosed a shape of an optical element characterized in that a held portion constituted by a locking projection or a protrusion provided at three or more points on a V-groove, U-groove or its outer peripheral surface is provided.

  Further, Patent Document 3 discloses a first transfer portion that forms an optical functional surface of an optical element, a second transfer portion that forms a non-optical functional surface, a predetermined recess provided in the second transfer portion, and / or Optical element molding for forming an optical element having an optical functional surface and a non-optical functional surface having depressions and / or protrusions corresponding to the concave portions and / or convex portions by press molding using a molding die having convex portions. A method has been proposed.

  Further, Patent Document 4 discloses an optical element in which a holding unit that abuts a fixing member that holds the optical element is provided outside the light beam effective area, and the holding unit holds one or more steps in the optical axis direction. An optical element characterized by having a portion is disclosed.

Japanese Patent Laid-Open No. 1-183612 JP 7-318774 A Japanese Patent Laid-Open No. 2004-256381 JP 2003-149518 A

  By the way, in the recent thin imaging apparatus, the shape of the optical element itself has a great influence on the thinning of the optical system. For this reason, in the shape of the optical element itself, particularly in the convex lens and the convex meniscus lens, it is necessary to make the thickness that affects the thinning of the optical system, such as the central part and the outer peripheral part of the optical element as thin as possible.

  However, since the side surface portion of the optical element is also thinned by making the optical element thin, the area held by the lens frame becomes small and it is difficult to attach to the lens frame. When attaching such an optical element thinner than the conventional one to the lens frame, it is difficult to use the conventional method or the methods proposed in Patent Documents 1 to 4 above.

  The present invention has been made in view of this point, and an object of the present invention is to easily attach an optical element thinner than the conventional one to a lens frame or the like.

  An optical element that solves the above problems is an optical element having an optical functional surface on an incident surface and an output surface, and has a rectangular optical effective region in the optical functional surface when viewed from the optical axis direction, The vertex of the optical effective region is located near the outer periphery of the optical element, and the ratio of the length of the diagonal of the optical effective region on the incident surface side and the diagonal of the optical effective region on the output surface side is: It is substantially 1, and has either a holding part for holding the optical element or a positioning part for determining the position of the optical element on the outer peripheral part of the optical effective area.

  According to the above optical element, it is possible to easily attach an optical element thinner than the conventional one to a lens frame or the like.

(A) Top view of the optical element according to the first embodiment, (b) a sectional view when the optical element according to the first embodiment is cut along a diagonal line xx ′, and (c) the optical element according to the first embodiment. Sectional view of a location yy 'other than the diagonal line Top view and side view of optical element according to Embodiment 2 Top view of thin optical element according to another embodiment of the present invention Top and side views of a thin optical element according to another embodiment

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment, components that perform the same operation may be denoted by the same reference numerals and the description thereof may be omitted. In addition, the “optical functional surface” in the present specification is a surface necessary for producing optical characteristics required for an optical element, and means a surface that becomes a path of light rays.

  In addition, the “optical effective area” in the present specification is an area existing in the optical function surface, and is actually used in the optical function surface when the optical element is mounted on an imaging device or the like, for example. Means an area.

  In addition, the “optical effective length” in the present specification means the length of a line segment in which both end points are at least on the optical functional surface.

(Embodiment 1)
Fig.1 (a) is a schematic top view when the optical element 1 which concerns on this embodiment is seen from the entrance plane side, FIG.1 (b) shows the optical element 1 of Fig.1 (a) xx. FIG. 1C is a cross-sectional view when the optical element of FIG. 1A is cut along yy ′.

  As shown in FIG. 1, the optical element 1 is a biconvex optical element.

  The optical element 1 has an incident surface 2 on which light is incident and an output surface 3 on which incident light is emitted. The entrance surface 2 and the exit surface 3 are optical functional surfaces that have almost all optical functions.

  Usually, an image sensor in an imaging apparatus has a rectangular imaging region. Therefore, the optical function surface of the optical element in the imaging apparatus is often rectangular.

  Therefore, as shown in FIG. 1A, the incident surface 2 of the optical element 1 has a rectangular optical effective region (hereinafter sometimes simply referred to as an optical effective region) 5 and an outer periphery of the optical effective region 5. The outer peripheral surface 4 is provided. The outer peripheral surface 4 is an example of an outer peripheral part.

  Although not shown, the exit surface 3 also has a rectangular optically effective region and an outer peripheral surface provided on the outer periphery thereof.

  In addition, since the optical element 1 which concerns on this embodiment should just be a surface where the rectangular optical effective area | region 5 has an optical function, the outer peripheral surface 4 does not need to be an optical function surface.

  Each vertex of the optical effective region 5 is provided in the vicinity of the outer periphery of the optical element 1. Accordingly, as shown in FIG. 1B, the length A of the diagonal line of the optical effective region 5 (hereinafter sometimes referred to as the optical effective length A) and the outer diameter C of the optical element 1 are substantially the same ( C≈A).

  Similarly, the length C of the diagonal line of the optically effective area of the emission surface 3 (hereinafter sometimes referred to as the optically effective length A ′) and the outer diameter C of the optical element 1 are substantially the same for the emission surface 3. (A′≈C).

  Further, the ratio between the optical effective length A of the incident surface 2 and the optical effective length A ′ of the output surface 3 is approximately 1 (A / A′≈1). In other words, when viewed from a direction perpendicular to the cross section when cut along a line (xx ′ in FIG. 1A) including the diagonal line of the optically effective area of the entrance surface and the exit surface (FIG. 1B). The diameter of the incident light incident on the incident surface 2 and the diameter of the emitted light emitted from the output surface 3 are substantially the same.

  Such a configuration can be realized by reducing the thickness in the optical axis direction at the outer peripheral portion of the optical element 1 having each vertex of the optical effective region in the vicinity of the outer periphery.

  More specifically, when the outer peripheral portion of the optical element 1 is thinned, the vertex of the optical effective region of the incident surface 2 and the vertex of the optical effective region of the output surface 3 become closer. When the vertex of the optical effective region of the incident surface 2 and the vertex of the optical effective region of the output surface 3 become close, the optical path from the vertex of the optical effective region of the incident surface 2 to the vertex of the optical effective region of the output surface 3 becomes short. Since the optical path is short, the light incident on the apex of the optical effective area of the incident surface 2 immediately reaches the apex of the optical effective area of the output surface 3. Therefore, when viewed from the optical axis direction, the vertex of the optical effective region of the incident surface 2 and the vertex of the optical effective region of the output surface 3 are substantially at the same position. Therefore, the ratio between the optical effective length A of the incident surface 2 and the optical effective length A ′ of the output surface 3 is approximately 1 (A / A′≈1).

  On the other hand, when viewed from a direction perpendicular to the cross section when cut by a line other than the diagonal line of the optical effective region 5 (y ′ in FIG. 1A) (FIG. 1C), the optical surface of the incident surface 2 The effective optical length B ′ of the exit surface 3 is shorter than the effective length B. That is, the ratio between the optical effective lengths other than the diagonal line is not approximately 1. This will be described.

  As described above, each apex portion of the optically effective area 5 is located in the vicinity of the outer periphery of the optical element 10, so that the thickness in the optical axis direction is thin. However, the thickness in the optical axis direction at each side of the optical effective region 5 is thicker than the thickness in the optical axis direction at each vertex of the optical effective region 5. Since the thickness in the optical axis direction is large, the optical path becomes long. Since the light incident on each side of the optically effective area 5 of the incident surface 2 is refracted by the incident surface 2 and reaches the output surface 3, the refracted light is closer to the optical axis side due to the longer optical path. Therefore, the optical effective length BB ′ of the exit surface 3 is shorter than the optical effective length B of the entrance surface 2. Therefore, the ratio between the optical effective lengths other than the diagonal is not approximately 1 (B / B ′ ≠ 1).

  In the conventional optical element, since the vertex of the rectangular optical effective area is not located near the outer periphery of the optical element, the area other than the rectangular optical effective area is wasted. However, in the optical element 1 according to the present embodiment, the vertex of the rectangular optical effective region is located near the outer periphery of the optical element, and the diagonal line of the optical effective region on the incident surface side and the optical effective region on the output surface side are Since the ratio of the length to the diagonal line is approximately 1, it is possible to increase the proportion of the optically effective area in the entrance surface and the exit surface. Accordingly, since the area other than the optical effective area can be reduced as compared with the conventional optical element, the optical element itself can be reduced in size and weight.

  Further, the optical element 1 according to the present embodiment has a short optical path from the apex of the optical effective area of the incident surface 2 to the apex of the optical effective area of the output surface 3, and therefore the outer peripheral portion is made thinner than the conventional optical element. Can do. As the outer peripheral portion becomes thinner, the central portion of the optical element 1 can also be made thinner. Therefore, the entire optical element 1 can be thinned.

  By adopting such an optical element 1 in an optical system such as an imaging apparatus, the optical system can be made thinner and smaller than before.

  When holding such an optical element 1, the region of the outer peripheral surface 4 can be used as a holding portion of the optical element 1.

  Therefore, even an optical element thinner than the conventional one that is difficult to hold can be easily held.

(Embodiment 2)
FIG. 2 is a top view and a cross-sectional view of the optical element 10 according to this embodiment.

  The optical element 10 according to this embodiment is different from the optical element 1 according to Embodiment 1 in that a part of the outer peripheral surface 4 is cut.

  As shown in FIG. 2, in the optical element 10, a part of the outer peripheral surface 4 on the outer periphery of the optical effective region 5 is cut to form a side surface 8. The side surface 8 is an example of an outer peripheral portion.

  When the optical element 10 is held by a holding member or the like, the side surface 8 can be used as a holding portion of the optical element 10. The side surface 8 also functions as a positioning portion for determining the position of the optical element 10.

  Therefore, even an optical element that is thinner than the conventional one that is difficult to hold and position can be easily held and positioned.

(Other embodiments)
In the above embodiment, the optical element is a biconvex lens.

  In the above-described embodiment, the holding and positioning unit is cut at only one place. However, the present invention is not limited to this. For example, the side 9 may be formed at two or more places as shown in FIG. Good. Such a configuration makes it easier to hold and position the optical element.

  Moreover, in the said embodiment, although the side surface was formed by cutting the outer peripheral surface, and it was set as the holding | maintenance and positioning part, it is not restricted to this, For example, as shown in FIG. 14 may have a holding and positioning hole 16 or the like.

  The above embodiment is not limited to the manufacturing method, and may be formed by any method such as polishing, press molding, injection molding, or the like.

  Moreover, the said embodiment is not restricted to material, Any materials, such as glass, a plastics, ceramics, may be sufficient.

  The present invention is not limited to the embodiments, and can be implemented in various other forms without departing from the spirit or main features thereof.

  The above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is defined by the claims, and is not limited by the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The optical element according to the present invention can be applied to an imaging apparatus such as a camera or a movie.

DESCRIPTION OF SYMBOLS 1,10 Optical element 2 Incidence surface 3 Outgoing surface 4 Outer peripheral surface 5, 15 Optical effective area 8, 9 Side surface for holding and positioning 16 Hole for holding and positioning A, A ', B, B' Optical effective length C Optical Element outer diameter

Claims (1)

An optical element having an optical function surface on an incident surface and an output surface,
When viewed from the optical axis direction, has a rectangular optical effective area in the optical functional surface,
The vertex of the optical effective area is located near the outer periphery of the optical element;
The ratio of the length of the diagonal line of the optical effective region on the incident surface side and the diagonal line of the optical effective region on the output surface side is approximately 1,
In the outer periphery of the optically effective area, it has either a holding unit for holding the optical element or a positioning unit for determining the position of the optical element.
Optical element.

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