JP2008034453A - Camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the unevenness of sensitivity in the central area or the peripheral area of an imaging device. <P>SOLUTION: The camera module includes an imaging device 1 wherein a plurality of photoelectric converters 12 and a lens array 2 placed way from the imaging device. The lens array 2 includes a first surface (upper face) wherein a plurality of micro lens 2a are formed and a second surface (lower face) opposite to the imaging device, and it is arranged on the surface side (upper side) of the imaging device wherein the photoelectric converters 12 are formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a camera module mounted on a mobile device such as a mobile phone or a digital still camera.

In recent years, for example, camera modules mounted on mobile phones or digital still cameras tend to be further reduced in size and thickness. A conventional camera module has a structure in which a plurality of microlenses are formed on the surface of an image sensor and light is incident on a photoelectric conversion unit via the plurality of microlenses, as shown in Patent Document 1 below. It has become.
Japanese Patent Laid-Open No. 10-163462

  However, with the recent trend of thinning, the light incident angle to the peripheral region on the light receiving surface of the image sensor is further reduced, and in the conventional structure in which a plurality of microlenses are formed on the surface of the image sensor However, it has been difficult to further reduce the sensitivity unevenness in the central region and the peripheral region of the image sensor.

  That is, since the light incident angle is further reduced as the photoelectric conversion unit formed in the peripheral region of the image sensor, the amount of light reaching the photoelectric conversion unit in the peripheral region of the image sensor is further reduced, compared to the central region. There is a problem that the image in the peripheral area becomes darker and the sensitivity becomes lower.

  The camera module of the present invention has been completed in view of the above problems, and an object thereof is to reduce sensitivity unevenness in the central region and the peripheral region of the image sensor.

  The camera module of the present invention includes an image pickup element on which a plurality of photoelectric conversion units are formed, and a lens array that is arranged apart from the image pickup element. The lens array has a first surface on which a plurality of microlenses are formed and a second surface facing the image sensor, and is disposed on the surface side of the image sensor on which the plurality of photoelectric conversion units are formed. ing. In addition, the camera module of the present invention includes an imaging device in which a plurality of photoelectric conversion units are formed, and an optical path conversion unit disposed above the imaging device. The optical path conversion unit emits light incident from the opposite side of the image sensor perpendicularly to the plurality of photoelectric conversion units of the image sensor.

  The camera module of the present invention has a first surface on which a plurality of microlenses are formed and a second surface facing the image sensor, and includes a lens array that is spaced apart from the image sensor. Accordingly, the difference in light incident angle between the central region and the peripheral region of the image sensor can be further reduced, and unevenness of sensitivity in the central region and the peripheral region of the image sensor can be reduced.

  An embodiment of a camera module of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a camera module of the present invention. FIG. 2 is a cross-sectional view showing the relationship between the image sensor 1 and the lens array 2 in the camera module of the present invention. The camera module according to the present invention includes an image sensor 1 and a lens array 2 that is disposed apart from the image sensor 1. The lens array 2 has a plurality of microlenses 2 a that guide light incident from the outside to the image sensor 1.

  The imaging device 1 includes a photoelectric conversion unit (light receiving unit) 12 and a light shielding unit 13 formed on a substrate 11 made of a semiconductor material, and an overcoat layer formed on the photoelectric conversion unit 12 and the light shielding unit 13. have. Here, the photoelectric conversion unit of the image sensor 1 is a part that receives light incident from the outside and outputs an electrical signal corresponding to the light, and is a part that converts incident light into electric charges. The image sensor 1 converts light incident on the photoelectric conversion unit 12 into an electric signal, and is mounted on the substrate 3.

  In the present invention, the lens array 2 is disposed on the surface side of the image sensor 1 on which the photoelectric conversion unit 12 is formed (above the image sensor 1 in FIG. 1) and spaced apart from the image sensor 1. A plurality of microlenses 2a are provided on the opposite surface (surface on which light is incident). Thus, the lens array 2 includes a first surface (a surface on which light is incident; an upper surface in FIG. 1) on which a plurality of microlenses 2 a are formed, and a second surface (FIG. 1) facing the image sensor 1. And the lower surface). The plurality of microlenses 2 a are formed in a convex shape on the opposite side (the side on which light is incident) with respect to the image sensor 1, and guide light incident from the outside to the photoelectric conversion unit 12 of the image sensor 1.

  In the camera module shown in FIG. 2, the plurality of microlenses 2 a of the lens array 2 are arranged corresponding to the plurality of photoelectric conversion units 12 of the imaging device 1. Here, “correspondingly” means that it is possible to indicate the relationship between at least all of the plurality of photoelectric conversion units 12 and the plurality of microlenses 2a. In the camera module shown in FIG. One of the lenses 2 a is associated with one of the plurality of photoelectric conversion units 12. That is, in the camera module shown in FIG. 2, the number of the plurality of microlenses 2a and the number of the plurality of photoelectric conversion units 12 are equal. The light incident on the plurality of microlenses 2a is incident on the photoelectric conversion units 12 of the image sensor 1 corresponding to the plurality of microlenses 2a. The plurality of microlenses 2 a of the lens array 2 are formed larger than the photoelectric conversion unit 12 of the image sensor 1. In the camera module shown in FIG. 2, the lens array 2 is an optical path conversion unit that emits light incident from the opposite side (external) of the image sensor 1 perpendicularly to the plurality of photoelectric conversion units 12 of the image sensor 1. is there.

  The lens array 2 is made of a translucent material. Here, the translucency of the lens array 2 means that at least a part of wavelengths of light incident from the outside can be transmitted. The specific material of the lens array 2 is, for example, a glass material such as borosilicate glass, or a highly transparent polymer material such as acrylic resin or methacrylic resin. Borosilicate glass is obtained by adding boric acid to a glass material, and is excellent in heat resistance and chemical resistance, and can form a molded product having a smooth surface. Thus, borosilicate glass is a translucent material with excellent optical properties. The lens array 2 is manufactured, for example, by pouring a molten high-purity glass material into a mold made of platinum (Pt) in which impurities are relatively less dissolved and cooling.

  In the camera module shown in FIG. 1, a lens 4 is disposed above (external side) the lens array 2. The lens 4 is disposed such that the lens array 2 is positioned between the lens 4 and the imaging device 1, and is supported by a lens holder 5 fixed on the substrate 3. The lens 4 is made of a translucent material. Here, the translucency of the lens 4 means that at least part of light incident from the outside can be transmitted. Examples of the translucent material of the lens 4 include translucent resins such as acrylic resin and methacrylic resin, and glass. The lens holder 5 is made of a thermosetting resin such as an epoxy resin, or a thermoplastic resin such as liquid crystal polymer, polyethylene, or polyester.

  Here, the incidence of light on the image sensor 1 in the camera module of the present invention will be described with reference to FIG. FIG. 3 schematically shows incident light on the image sensor 1 and the lens array 2 in the camera module shown in FIG. In FIG. 3, light incident on the lens array 2 (light incident from the outside) is indicated as L2, and light incident on the image sensor 1 is indicated as L1. The camera module of the present invention includes a plurality of microlenses formed in a convex shape and includes a lens array 2 that is spaced apart from the image sensor 1, thereby allowing a light receiving surface (upper surface) of the image sensor 1. ) In the central region Rc and the incident angle of the light L2 in the surrounding region Rp is reduced to reduce the difference in the amount of received light in the central region Rc and the surrounding region Rp of the image sensor 1. Can do. As described above, in the present invention, it is possible to reduce the unevenness in resolution in the central region Rc and the surrounding region Rp of the image sensor 1.

  (Second Example of Lens Array) Next, another example (second example) of the lens array 2 in the camera module of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram showing the configuration of the second example of the lens array 2. In the second example of the lens array 2, the plurality of microlenses 2 a located in the peripheral region Rp of the lens array 2 are formed larger than the plurality of microlenses 2 a located in the central region Rc of the lens array 2. In the camera module shown in FIG. 4, the plurality of microlenses 2 a located in the peripheral region Rp of the lens array 2 are formed thicker than the plurality of microlenses 2 a located in the central region Rc of the lens array 2. In the camera module shown in FIG. 4, the plurality of microlenses 2 a located in the peripheral region Rp of the lens array 2 have a larger diameter than the plurality of microlenses 2 a located in the central region Rc of the lens array 2.

  In the example of the lens array 2 shown in FIG. 4, the plurality of microlenses 2 a are gradually increased from the central region Rc of the lens array 2 toward the surrounding region Rp. In the camera module of the present invention, the plurality of microlenses 2a located in the peripheral region Rp of the lens array 2 are larger than the plurality of microlenses 2a located in the central region Rc of the lens array 2, so that the light receiving surface of the imaging device 1 The unevenness in the amount of light incident on the image sensor 1 can be further reduced, and the unevenness in resolution in the central region Rc and the surrounding region Rp of the image sensor 1 can be reduced. That is, in the camera module of the present invention, the lens array 2 (optical path conversion means) is formed with a plurality of microlenses 2a so that the amount of conversion of the optical path is larger in the peripheral region Rp than in the central region Rc. With such a configuration, it is possible to reduce unevenness in resolution in the central region Rc and the surrounding region Rp of the image sensor 1.

  (Third Example of Lens Array) Next, another example (third example) of the lens array 2 in the camera module of the present invention will be described with reference to FIG. FIG. 5 is a schematic diagram showing the configuration of the third example of the lens array 2. In the third example of the lens array 2, a plurality of microlenses 2 a are formed with surfaces that are inclined toward the center of the lens array 2. In the camera module shown in FIG. 5, the plurality of microlenses 2 a located in the peripheral region Rp of the lens array 2 are formed larger than the plurality of microlenses 2 a located in the central region Rc of the lens array 2. In the camera module shown in FIG. 5, the plurality of microlenses 2 a located in the peripheral region Rp of the lens array 2 are formed thicker than the plurality of microlenses 2 a located in the central region Rc of the lens array 2.

  Further, in the camera module shown in FIG. 5, the plurality of microlenses 2 a have an upper surface whose inclination angle increases from the central region Rc of the lens array 2 toward the peripheral region Rp. In the camera module of the present invention, the plurality of microlenses 2 a are formed with a surface inclined toward the center of the lens array 2, thereby further reducing unevenness in the amount of light incident on the light receiving surface of the image sensor 1. Thus, it is possible to reduce the unevenness in resolution in the central region Rc and the surrounding region Rp of the image sensor 1. That is, in the camera module of the present invention, the lens array 2 (optical path conversion means) is formed with a plurality of microlenses 2a so that the amount of conversion of the optical path is larger in the peripheral region Rp than in the central region Rc. With such a configuration, it is possible to reduce unevenness in resolution in the central region Rc and the surrounding region Rp of the image sensor 1.

  (Fourth Example of Lens Array) Next, another example (fourth example) of the lens array 2 in the camera module of the present invention will be described with reference to FIG. FIG. 6 is a schematic diagram showing the configuration of the fourth example of the lens array 2. In the fourth example of the lens array 2, the plurality of microlenses 2 a located in the peripheral region Rp of the lens array 2 are larger than the plurality of microlenses 2 a located in the central region Rc of the lens array 2 and the inclination angle of the upper surface Is formed large. With such a configuration, the camera module of the present invention can reduce unevenness in resolution in the central region Rc and the surrounding region Rp of the image sensor 1. That is, in the camera module of the present invention, the lens array 2 (optical path changing means) is formed with a plurality of microlenses 2a so that the amount of conversion of the optical path is larger in the peripheral area Rp than in the central area Rc. With such a configuration, it is possible to reduce unevenness in resolution in the central region Rc and the surrounding region Rp of the image sensor 1. Note that the microlens referred to here has at least a function of converting the optical path, and the surface of the plurality of microlenses 2a may have a planar structure.

  (Fifth Example of Lens Array) Next, another example (fifth example) of the lens array 2 in the camera module of the present invention will be described with reference to FIG. FIG. 7 is a schematic diagram showing the configuration of the fifth example of the lens array 2. In the fifth example, a near-infrared shielding film 27 is formed on the surface of the lens array 2. In the lens array 2 shown in FIG. 7, the near-infrared shielding film 27 is formed on the second surface of the lens array 2 (the surface facing the image sensor 1; the lower surface in FIG. 7). Here, in the present invention, the near-infrared shielding film 27 absorbs at least part of near-infrared rays in the wavelength band of 700 nm to 1000 nm, and is, for example, an optical filter made of a dielectric multilayer film. The near-infrared shielding film (dielectric multilayer film) 27 is composed of a dielectric layer having a relatively high refractive index made of a dielectric material having a refractive index of 1.7 or more and a dielectric material having a refractive index of 1.6 or less. And a relatively low refractive index dielectric layer. In this dielectric multilayer film, a high refractive index dielectric layer and a low refractive index dielectric layer are alternately laminated over several tens of layers by vapor deposition or sputtering.

  In the camera module shown in FIG. 7, the near-infrared shielding film 27 has a maximum reflectance of 20% or less in the wavelength band of 400 nm to 600 nm, and a minimum reflectance in the wavelength band of 700 nm to 1000 nm. 90% or more.

  The camera module of the present invention can improve the resolution by forming a near-infrared shielding film on the surface of the lens array 2.

  (Sixth Example of Lens Array) Next, another example (sixth example) of the lens array 2 in the camera module of the present invention will be described with reference to FIG. FIG. 8 is a schematic diagram showing the configuration of the sixth example of the lens array 2. In the camera module of the present invention, an antireflection film is formed on the surface of the lens array 2. Here, the antireflection film in the camera module of the present invention reduces reflection of at least a part of the visible region of 450 nm to 600 nm. In the camera module shown in FIG. 8, the antireflection film 28 has a maximum reflectance of 2% or less in the visible region of 450 nm to 600 nm. In the camera module shown in FIG. 8, the antireflection film 28 is formed on the second surface of the lens array 2 (the surface facing the image sensor 1; the lower surface in FIG. 8).

  The reflective film 28 is made of an insulating material having a refractive index of 1.7 or higher and an insulating material having a refractive index of 1.6 or lower. Examples of the insulating material having a refractive index of 1.7 or more include tantalum pentoxide, titanium oxide, niobium pentoxide, lanthanum oxide, and zirconium oxide. Examples of the insulating material having a refractive index of 1.6 or less include silicon oxide, aluminum oxide, lanthanum fluoride, and magnesium fluoride. Considering mechanical properties such as hardness and stability, and optical properties such as refractive index related to the function as an optical filter, titanium oxide as a relatively high refractive index insulating material, relatively low refractive index As the insulating material, silicon oxide is desirable.

  The camera module of the present invention can improve the resolution by forming an antireflection film on the surface of the lens array 2.

It is sectional drawing which shows the structure of the camera module of this invention. It is sectional drawing which shows the relationship between the image pick-up element 1 and the lens array 2 in the camera module of this invention. FIG. 2 schematically shows incident light on an image sensor 1 and a lens array 2 in the camera module shown in FIG. 1. FIG. 6 is a schematic diagram showing a configuration of a second example of the lens array 2. It is a schematic diagram which shows the structure of the 3rd example of the lens array 2. FIG. It is a schematic diagram which shows the structure of the 4th example of the lens array. FIG. 10 is a schematic diagram illustrating a configuration of a fifth example of the lens array 2. It is a schematic diagram which shows the structure of the 6th example of the lens array.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Imaging device 2 ... Lens array 2a ... Several micro lens 3 ... Base | substrate 4 ... Lens 5 ... Lens holder

Claims (11)

An image sensor in which a plurality of photoelectric conversion units are formed on a substrate;
The imaging device has a first surface on which a plurality of microlenses are formed and a second surface facing the imaging device, and the imaging device is provided on a surface of the imaging device on which the plurality of photoelectric conversion units are formed. And a lens array spaced apart from each other. The camera module according to claim 1, wherein the plurality of microlenses are arranged corresponding to the plurality of photoelectric conversion units of the imaging element. The camera module according to claim 1, further comprising a lens arranged so that the lens array is positioned between the imaging element. The camera module according to claim 1, further comprising a near-infrared shielding film formed on a surface of the lens array. The camera module according to claim 4, wherein the near-infrared shielding film is formed on the second surface of the lens array. The camera module according to claim 1, further comprising an antireflection film formed on a surface of the lens array. The camera module according to claim 6, wherein the antireflection film is formed on the second surface of the lens array. The camera module according to claim 1, wherein the plurality of microlenses positioned in a peripheral region of the lens array are larger than the plurality of microlenses positioned in a central region of the lens array. . 9. The camera module according to claim 1, wherein a surface that is inclined toward a central portion of the lens array is formed on the plurality of microlenses. 10. An image sensor in which a plurality of photoelectric conversion units are formed on a substrate;
An optical path conversion unit that is disposed above the image sensor and emits light incident from the opposite side of the image sensor perpendicularly to the plurality of photoelectric conversion units of the image sensor. The optical path changing means has a plurality of microlenses,
The optical path conversion amount of the plurality of microlenses positioned in a peripheral region of the optical path conversion unit is larger than that of the plurality of microlenses positioned in a central region of the optical path conversion unit. The camera module.

Images