JP2009169147A - Lens, lens module, and camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of degradation of the quality of an image formed on an image forming face degrades, caused by light reflection on the front face (the object side face) of the flange part. <P>SOLUTION: A lens module disposed on an imaging element 2 includes: a lens 4 having a lens portion by which light made incident from the object side is imaged on the imaging face of the image sensor, and a flange part disposed on the outer periphery of the lens part; and a holding member 5 which holds the flange part of the lens 4. The flange part has an exposure face that exposes between the lens part and the holding member 5. The exposure face inclines in a direction away from the object side as it moves away from the lens part toward the holding member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lens, a lens module, and a camera module.

  In recent years, it has become common for digital cameras to be incorporated into small electronic devices such as mobile phones (mobile communication terminals). As mobile phones become thinner, digital cameras built into mobile phones are becoming smaller.

  In order to reduce the size of the digital camera, it is necessary to reduce the size of the lens module fixed above the image sensor. However, even if the lens module is simply made smaller, uneven brightness may occur on the imaging surface.

Patent Documents 1 and 2 disclose a lens having a three-piece structure in which a stop is disposed on the object side. By adopting a three-lens lens, the above-described problem of luminance unevenness is avoided while the lens module is reduced in size.
JP 2006-243093 A JP 2006-309148 A

  As a method for fixing the lens to the lens barrel, there is a method in which the lens flange is held by the lens barrel and the lens is fixed to the lens barrel. In general, a diaphragm is provided above the object lens (on the object side).

  When reducing the size of the lens module as described above, extraneous light may be incident on the flange portion of the lens even if a diaphragm is disposed above the objective lens. The flange portion is provided to fix the lens portion to the lens barrel, and is not a portion to which any lens action is added. If extraneous light is reflected on the front surface of the flange portion, the light is diffusely reflected in the lens module, and the quality of the image formed on the imaging surface may deteriorate.

  The present invention has been made to solve such a problem, and suppresses deterioration of the quality of an image formed on the imaging surface due to reflection of light on the front surface of the flange portion. The purpose is to do.

  A lens module according to the present invention is a lens module provided on an image pickup device, and includes a lens portion that forms an image of light incident from the object side on an image pickup surface of the image pickup device, and a flange provided on an outer periphery of the lens portion. And a holding member that holds the flange portion of the lens, and the flange portion has an exposed surface that is exposed between the lens portion and the holding member. As the distance from the lens portion toward the holding member increases, the distance from the object side increases.

  Incident light incident on the exposed surface can be reflected at a higher angle by inclining the exposed surface in a direction away from the object side. Therefore, even if light of a predetermined wavelength component included in the reflected light from the exposed surface is reflected again by the inner surface of the holding body, the re-reflected light is incident on the lens unit and passes through the lens unit. Imaging on the imaging surface is suppressed. As a result, the occurrence of flare in the image formed on the imaging surface of the image sensor is suppressed.

  The holding member may be a cylindrical member having an opening whose inner diameter increases from the object side toward the lens unit.

  It is preferable that the flange portion has a portion whose thickness decreases as the distance from the lens portion increases.

  The lens unit may include a first convex part on the object side and a second convex part on the imaging element side.

  A camera module according to the present invention is a camera module including an imaging device and a lens module provided on the imaging device, and the lens module forms an image of light incident from the object side on an imaging surface of the imaging device. A lens having a lens portion and a flange portion provided on an outer periphery of the lens portion; and a holding member that holds the flange portion of the lens, and the flange portion is between the lens portion and the holding member. The exposed surface is inclined in a direction away from the object side as it is separated from the lens portion toward the holding member.

  A lens according to the present invention is a lens that forms an image of light incident from the object side on an imaging surface of an imaging device, and includes a lens portion and a flange portion provided on an outer periphery of the lens portion, and the flange The part has an inclined surface that inclines in a direction away from the object side as the distance from the lens part increases, and the inclined surface is connected to the lens part.

  It is preferable that the flange portion has a portion whose thickness decreases as the distance from the lens portion increases.

  The lens unit may include a first convex part on the object side and a second convex part on the imaging element side.

  According to the present invention, it is possible to suppress deterioration of the quality of an image formed on the imaging surface due to reflection of light on the front surface of the flange portion.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each embodiment is simplified for convenience of explanation. Since the drawings are simple, the technical scope of the present invention should not be interpreted narrowly based on the drawings. The drawings are only for explaining the technical matters, and do not reflect the exact sizes or the like of the elements shown in the drawings. The same elements are denoted by the same reference numerals, and redundant description is omitted. Words indicating directions such as up, down, left, and right are used on the assumption that the drawing is viewed from the front.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic perspective view of a camera module. FIG. 2 is a schematic diagram illustrating a schematic cross-sectional configuration of the camera module. FIG. 3 is a schematic diagram showing the shape of the lens. FIG. 4 is an explanatory diagram for explaining an inclination angle, an incident angle, and a reflection angle. FIG. 5 is a table for explaining the relationship between the tilt angle, the incident angle, and the reflection angle. FIG. 6 is a graph for explaining the relationship between the tilt angle, the incident angle, and the reflection angle.

  FIG. 1 shows a camera module 50. As shown in FIG. 1, the camera module 50 is a substantially cylindrical member. The camera module 50 includes a lens barrel 5 and a housing 6. An opening OP <b> 1 is provided in the front surface 5 a of the lens barrel 5. The lens barrel 5 is held by the housing 6.

  FIG. 2 shows a cross-sectional configuration of the camera module 50 of x1-x1 in FIG. As shown in FIG. 2, the camera module 50 includes a wiring board 1, an image sensor 2, a cover glass 3, a lens (objective lens) 4, a lens barrel (holding body) 5, and a housing 6. Note that the range module disposed in front of (above) the image sensor 2 is formed by the lens 4 and the lens barrel 5.

  The camera module 50 acquires an image formed on the imaging surface 2 a of the imaging device 2 via the lens 4. As will be apparent from the following description, the lens barrel 5 provided with the opening OP1 functions as a diaphragm. By employing the lens barrel 5 having such a shape, a front aperture type lens module can be realized with a simple configuration. By adopting a front aperture type lens module, the camera module can be made thinner. Note that the housing 5 is substantially opaque to visible light.

  First, the arrangement relationship of each element constituting the camera module 50 will be described. As shown in FIG. 2, the image sensor 2 is mounted on the wiring board 1. The housing 6 is mounted on the wiring board 1 on which the image sensor 2 is mounted. The cover glass 3 is supported by the housing 6 and is disposed above the image sensor 2. The lens barrel 5 is held by the housing 6 while holding the lens 4. The lens barrel 5 is disposed above the cover glass 3. In this way, the lens 4 and the cover glass 3 are sequentially arranged from the object side to the imaging surface 2a of the imaging device 2. Note that the imaging surface 2a of the imaging element 2 is also an imaging surface.

  Hereinafter, each element constituting the camera module 50 will be described.

  The wiring board 1 is a plate-like member in which metal wiring is applied to a normal glass epoxy board. The wiring board 1 is electrically connected to a board on which the camera module 50 is mounted. The wiring board 1 may be a flexible board (for example, film wiring).

  The imaging element 2 has an imaging surface 2a on which pixels are arranged in a matrix. The image sensor 2 is a general solid-state image sensor such as a CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, or a TFT (Thin Film Transistor) sensor. The specific configuration of the image sensor 2 is arbitrary. The shape of each pixel and the arrangement mode of the pixels are arbitrary.

  The cover glass 3 is a transparent plate-like glass plate.

  The lens 4 is an optical element in which a heat resistant material (for example, glass, silicone resin, etc.) is molded. The lens 4 is an objective lens located closest to the object.

  The configuration of the lens 4 is shown in FIG. FIG. 3A shows a schematic cross-sectional configuration of the lens 4. FIG. 3A shows a schematic front configuration of the lens 4.

  As shown in FIG. 3A, the lens 4 has a lens portion 10 and a flange portion 11.

  The lens unit 10 is a part that functions optically. The lens portion 10 includes a convex portion 10 a that protrudes forward with respect to the flange portion 11, and a convex portion 10 b that protrudes rearward with respect to the flange portion 11. The convex portion 10a has a lens surface 10c. The convex portion 10b has a lens surface 10d. The light incident on the lens unit 10 receives a lens action at the convex portions 10a and 10b, and forms an image on the imaging surface 2a of the imaging element 2 described above. In addition, the optical axis AX of the convex part 10a and the optical axis AX of the convex part 10b correspond. An antireflection film is formed on the lens surfaces 10c and 10d.

  The flange portion 11 is a plate-like portion formed on the outer periphery of the lens portion 10. The flange portion 11 is a portion attached to the lens barrel 5. In addition, the flange part 11 has the front surface 11a, the back surface 11b, and the front end surface 11c. An antireflection film is not formed on the front surface 11a.

  The flange portion 11 has a tapered shape from the base portion connected to the lens portion 10 toward the tip. In other words, the thickness of the flange portion 11 decreases as the distance from the optical axis AX increases.

  Specifically, as schematically shown in FIG. 3A, the thickness of the base portion of the flange portion 11 is T1, the thickness of the intermediate portion of the flange portion 11 is T2, and the thickness of the tip portion of the flange portion 11 is Assuming T3, the relationship T1> T2> T3 is established.

  At this time, the front surface 11a of the flange portion 11 is inclined in a direction away from the object side as the distance from the optical axis AX increases. In other words, an inclined surface that is separated from the object side as the distance from the optical axis AX is formed on the front surface 11 a of the flange portion 11. By using the front surface 11a of the flange portion 11 as an inclined surface, incident light incident on the inclined surface can be reflected at a higher angle as will be described later. As a result, it is possible to suppress the occurrence of flare in the image formed on the imaging surface 2a of the imaging element 2. This point will become clear from the following description.

  In addition, the thickness (width along the optical axis AX) of the flange portion 11 is preferably 0.1 mm or more. This makes it easy to center the lens when attaching the lens 4 to the lens barrel 5.

  As shown in FIG. 3B, the top view shape of the lens unit 10 is circular. Similarly, the top view shape of the flange part 11 is circular.

  The front surface 11a of the flange portion 11 is connected to the lens surface 10c of the convex portion 10a. Therefore, the inclined surface coinciding with the front surface 11a of the flange portion 11 is also connected to the lens surface 10c of the convex portion 10a. A boundary line 12 is formed between the front surface 11a and the lens surface 10c. The boundary line 12 coincides with the inner side of the front surface 11a. The boundary line 12 coincides with the outer periphery of the lens surface 10c.

  Again, referring back to FIG.

  The lens barrel 5 is a member formed by molding a thermoplastic resin (for example, polyphthalamide resin, liquid crystal polymer, polyphenylene sulfide resin, or the like). The lens barrel 5 absorbs light in the visible light band. The lens barrel 5 may be manufactured from a black resin.

  The lens barrel 5 is a cylindrical member that extends along the optical axis AX. The lens barrel 5 has a front surface 5a and a back surface 5b. The lens barrel 5 has an opening OP1 extending from the front surface 5a to the back surface 5b. The diameter of the opening OP1 gradually increases from the front surface 5a toward the back surface 5b. In addition, the lens barrel 5 has a recess 7 on the inner side surface to which the lens 4 is locked.

  The lens barrel 5 has an upper tube portion 5p, an intermediate tube portion 5r, and a lower tube portion 5q. The width along the x-axis (axis perpendicular to the optical axis AX) of the upper tube portion 5p gradually decreases from the upper side to the lower side. The width along the x-axis of the middle cylinder portion 5r is substantially constant from the upper side to the lower side. The width of the lower cylinder portion 5q gradually decreases from the upper side to the lower side along the x axis. The above-mentioned concave portion 7 is formed corresponding to the middle cylinder portion 5r. The concave portion 7 is formed by the lower side surface of the upper cylindrical portion 5p, the inner side surface of the middle cylindrical portion 5r, and the upper side surface of the lower cylindrical portion 5q. An aperture having a shape corresponding to the diameter of the opening OP1 is set above the lens 4 (on the object side).

  The distal end portion of the flange portion 11 of the lens 4 is accommodated in the concave portion 7 of the lens barrel 5. The front surface 11 a of the flange portion 11 is partially exposed between the lens portion 10 and the lens barrel 5. In other words, an exposed surface that is exposed between the lens unit 10 and the lens barrel 5 is formed on the front surface 11 a of the flange unit 11.

  When the flange portion 11 is partially exposed in this manner, extraneous light is reflected on the exposed surface of the flange portion 11 and multiple reflected in the lens module, thereby forming an image on the image pickup surface 2a of the image pickup device 2. The problem is that flare occurs in the image.

  In the present embodiment, in view of this point, the above-described exposed surface is the above-described inclined surface. Therefore, incident light incident on the exposed surface can be reflected at a higher angle, and the occurrence of flare in the image formed on the imaging surface 2a of the imaging device 2 can be effectively suppressed. This point will be described later with reference to FIGS.

  The housing 6 is a cylindrical member that extends along the optical axis. The housing 6 is a member in which a thermoplastic resin (for example, polyphthalamide resin, liquid crystal polymer, polyphenylene sulfide resin, or the like) is molded. The housing 6 is mounted on the wiring substrate 1 on which the imaging device 2 is mounted in a state where the lens barrel 5 that holds the lens 4 is held. A wiring board 1, an image sensor 2, a cover glass 3, and a lens barrel 5 are accommodated in the housing 6.

  The housing 6 has a protruding portion 6c protruding inward. The cover glass 3 and the lens barrel 5 are disposed above the protrusion 6c. The wiring board 1 and the image sensor 2 are disposed below the protrusion 6c.

  In addition, the manufacturing method of the camera module 50 is arbitrary. The camera module 50 may be manufactured by laminating the wiring substrate 1, the image sensor 2, the housing 6, the cover glass 3, and the lens barrel 5 that holds the lens 4 in this order. A method of storing the lens 4 in the lens barrel 5 is arbitrary. If the lens barrel 5 is structured to be separable into two parts, and the lens 4 is sandwiched between the two separated parts, the lens 4 is suitably accommodated in the lens barrel 5.

  Hereinafter, with reference to FIG. 4 thru | or FIG. 6, the effect of making the exposed surface formed in the front surface 11a into an inclined surface is demonstrated.

  As schematically shown in FIG. 4, an angle formed by the axis X2 and the front surface 11a is defined as an inclination angle θ1. The axis line X2 is an axis line orthogonal to the optical axis AX. Further, an angle formed by the axis X3 and the optical path of the incident light is set as an incident angle θ2 (degrees). The angle formed by the axis X3 and the optical path of the reflected light is defined as a reflection angle θ3 (degrees). The axis line X3 coincides with the perpendicular line of the front surface 11a of the flange portion 11.

  As shown in FIGS. 5 and 6, when the inclination angle θ1 is changed from 0 degree to 30 degrees, the reflection angle θ3 becomes a value higher than the incident angle θ2. That is, by setting the inclination angle θ1> 0, incident light can be reflected at a higher angle. By reflecting the incident light at a higher angle in this way, the component that is reflected again on the inner surface of the upper cylindrical portion 5p out of the light reflected on the exposed surface of the flange portion 11 and enters the lens portion 10 is changed. It can be effectively reduced.

  When the tilt angle θ1 is changed from 0 degree to −30 degrees, the reflection angle θ3 becomes a value lower than the incident angle θ2. When the inclination angle θ1 <0 is set, incident light is reflected at a lower angle. Therefore, out of the extraneous light reflected by the exposed surface of the flange portion 11, it is reflected again by the inner surface of the upper tube portion 5 p and increases the component incident on the lens portion 10. Therefore, in order to suppress the occurrence of flare in the image formed on the imaging surface 2a of the imaging device 2, it is necessary to set the inclination angle θ1> 0.

  As is clear from the above description, in the present embodiment, the exposed surface of the flange portion 11 is inclined in a direction away from the object side. Therefore, the reflection angle of incident light incident on the exposed surface can be set to a higher angle. In this way, the component of the extraneous light reflected by the exposed surface of the flange portion 11 that is reflected again by the inner surface of the upper tube portion 5p and incident on the lens portion 10 can be effectively reduced. As a result, it is possible to suppress the occurrence of flare in the image formed on the imaging surface 2a of the imaging element 2.

  In the present embodiment, as a secondary effect, when the lens 4 is formed by injection, it can be easily removed from the mold. Further, when the lens is processed by cutting, the cutting bite easily enters the boundary portion between the flange portions, and cutting processing is facilitated.

  The technical scope of the present invention is not limited to the above-described embodiment. The present invention can also be applied to lenses other than objective lenses. The number of lenses arranged on the image sensor is arbitrary. Materials such as a lens, a lens barrel, and a housing are arbitrary. The specific configuration of the image sensor is arbitrary. The flange portion may be referred to as an edge portion. Further, the front surface 11a or the back surface 11b of the flange portion may be referred to as an edge surface.

1 is a schematic perspective view of a camera module according to a first embodiment of the present invention. It is a schematic diagram which shows schematic cross-sectional structure of the camera module concerning 1st Embodiment of this invention. It is a schematic diagram which shows the shape of the lens concerning 1st Embodiment of this invention. It is explanatory drawing for demonstrating an inclination angle, an incident angle, and a reflection angle. It is a table | surface for demonstrating the relationship between an inclination angle, an incident angle, and a reflection angle. It is a graph for demonstrating the relationship between an inclination angle, an incident angle, and a reflection angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wiring board 2 Image pick-up element 2a Image pick-up surface 3 Cover glass 4 Lens 5 Lens barrel 5a Front surface 5b Back surface 5p Upper cylinder part 5r Middle cylinder part 5q Lower cylinder part 6 Case 6c Projection part 7 Concave part 10 Lens part 10a Convex part 10b Convex part 10c Lens surface 10d Lens surface 11 Flange portion 11a Front surface 11b Rear surface 11c Front end surface 12 Boundary line θ1 Inclination angle θ2 Incident angle θ3 Reflection angle

Claims (8)

A lens module provided on the image sensor,
A lens unit that forms light on the imaging surface of the imaging element with light incident from the object side, and a lens having a flange unit provided on the outer periphery of the lens unit;
A holding member for holding the flange portion of the lens;
With
The flange portion has an exposed surface exposed between the lens portion and the holding member,
The exposure module is a lens module that inclines in a direction away from the object side as it moves away from the lens portion toward the holding member.   The lens module according to claim 1, wherein the holding member is a cylindrical member having an opening whose inner diameter increases from the object side toward the lens unit.   2. The lens module according to claim 1, wherein the flange portion has a portion whose thickness decreases as the distance from the lens portion increases.   2. The lens module according to claim 1, wherein the lens unit includes a first convex part on an object side and a second convex part on the imaging element side. A camera module comprising an imaging device and a lens module provided on the imaging device,
The lens module is
A lens unit that forms light on the imaging surface of the imaging element with light incident from the object side, and a lens having a flange unit provided on the outer periphery of the lens unit;
A holding member for holding the flange portion of the lens;
With
The flange portion has an exposed surface exposed between the lens portion and the holding member,
The exposed surface inclines in a direction away from the object side as it moves away from the lens unit toward the holding member. A lens for imaging light incident from the object side on an imaging surface of an image sensor;
The lens part,
A flange portion provided on the outer periphery of the lens portion;
With
The flange portion has an inclined surface that inclines in a direction away from the object side as being away from the lens portion,
The inclined surface is a lens connected to the lens unit.   The lens according to claim 6, wherein the flange portion has a portion whose thickness decreases as the distance from the lens portion increases.   The lens according to claim 6, wherein the lens unit includes a first convex part on an object side and a second convex part on the imaging element side.

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