JP5621615B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus used for various purposes such as an in-vehicle camera, a surveillance camera, an industrial camera, and a medical camera, and more particularly to an ultra-small imaging apparatus using a lens array.

  Imaging devices are used for various purposes such as in-vehicle cameras, surveillance cameras, industrial cameras, medical cameras, etc., but this kind of imaging devices should generally be installed in any place and inconspicuously. Therefore, it is required to reduce the size and thickness of the device. Therefore, an ultra-small image pickup apparatus that uses a lens array in which a plurality of lenses are arranged in an array and receives an image of an object formed by the plurality of lenses in the lens array on an image pickup element formed on a substrate is conventionally provided. Have been proposed (for example, Patent Document 1, Patent Document 2, etc.).

  Recently, in this type of imaging apparatus, there is a demand for imaging a wide range, and in addition to downsizing, a wide angle is also required. However, when the wide angle is set, there is a problem that the lens becomes dark or the MTF around the image deteriorates. If the lens is brightened at a wide angle and the deterioration of the MTF is also suppressed, it is necessary to superimpose several lenses. In this case, however, the accuracy of the lens position is now severe. Therefore, if the positional accuracy of the lens is lowered due to a temperature change or a change over time, the MTF is impaired, which causes a problem in terms of reliability.

  The present invention has been made in view of the above problems, and provides an ultra-compact and wide-angle compound-eye imaging device that is brighter, less MTF-degraded, and more reliable than a wide-angle lens using a plurality of lenses. It is to provide.

  In the present invention, an image is approximately formed by each of a lens array provided at a position facing a subject, in which a plurality of lenses are arrayed, and a plurality of lenses provided on the image plane side of the lens array. In an imaging apparatus having an imaging device that captures a compound eye image that is a set of single-eye images of the subject, the lens array is curved convexly with respect to the subject side, and between the lens array and the imaging device. In addition, there is provided means for bending the light flux so that the optical axis of each lens of the lens array is perpendicular to the light receiving surface of the image sensor.

  Specifically, the lens array tilts its end lens outward. The means for bending the light beam is a triangular prism whose surface corresponding to the lens array is curved in a concave shape opposite to the lens array, or a hologram element having an uneven shape on the surface facing the lens array.

  According to the imaging apparatus of the present invention, it is possible to capture a wide-angle compound eye that is brighter, has less MTF deterioration, and is more reliable than a wide-angle lens that uses a plurality of lenses.

It is sectional drawing of the prior art example of an imaging device. It is an external view of the imaging device of FIG. It is sectional drawing of another prior art example of an imaging device. It is sectional drawing of one Example of the imaging device of this invention. It is a disassembled perspective view of the imaging device of FIG. It is sectional drawing of another Example of the imaging device of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a conventional example of an ultra-small image pickup apparatus using a lens array will be described. FIG. 1 is a cross-sectional view of a conventional example of this type of imaging apparatus. In FIG. 1, reference numeral 1 denotes a microlens array in which a plurality of lenses are arrayed (hereinafter simply referred to as a lens array), and here, it is assumed to be composed of 4 × 2 lenses. The lens array 1 is held by a lens holder 2. Reference numeral 3 denotes a substrate, and a sensor light receiving unit 6 which is an image sensor such as a CCD sensor or a CMOS sensor is formed at a position facing the lens array 1. A drive circuit, a signal processing circuit, and the like are also formed on the substrate 3, but are omitted in FIG. A diaphragm plate 4 having a plurality of holes corresponding to each lens is provided on the side of the lens array 1 facing the subject, and adjacent to the side of the lens array 1 facing the sensor light receiving unit 6. A light shielding plate 5 is provided for preventing crosstalk of light rays between the lenses.

  Here, a gap of about 0.5 mm is provided between the lens holder 2 and the substrate 6, and an image obtained from the sensor light receiving unit 6 is monitored. From the monitor image, tilt adjustment of the entire lens holder and X, The position is adjusted in the Y- and Z-axis directions, the gap 10 is filled with an adhesive 10 and the like, and the lens holder 2 and the substrate 3 are fixed. FIG. 2 is a perspective view of the completed imaging apparatus.

  In such an imaging apparatus, if a lens is brightened at a wide angle and deterioration of MTF is also suppressed, it is necessary to superimpose several lenses.

  FIG. 3 is a cross-sectional view of the image pickup apparatus shown in FIG. 1 when the number of lenses is increased to obtain a wide angle. In FIG. 3, reference numerals 1-1 and 1-2 denote lens arrays, respectively, and the other configurations are the same as those in FIG. In the case of the configuration of FIG. 3, the positional accuracy of the lens array 1-1 and the lens array 1-2 is a problem. If the accuracy of the positional relationship between the two decreases, the MTF deteriorates and the reliability is impaired.

  Next, the imaging apparatus of the present invention will be described. FIG. 4 is a sectional view of an embodiment of the imaging apparatus according to the present invention, and FIG. 5 is an exploded perspective view. 4 and 5, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. In this embodiment, the lens array 1 is curved in a convex shape with respect to the subject side, and each lens of the lens array 1 is interposed between the lens array 1 and the sensor light receiving unit (imaging device) 6. A triangular prism 7 is provided as means for bending the light flux of the lens so that the optical axis is perpendicular to the light receiving surface of the sensor light receiving unit 6. 4 and 5, the lens array 1 has its end lens inclined outward, but this is only an example, and the entire lens array may be curved. The surface of the triangular prism 7 that faces the lens array 1 is curved in a concave shape opposite to the lens array 1. Here, the end is inclined inward. The light shielding plate 5 is disposed between the triangular prism 7 and the sensor light receiving unit 6. Further, the diaphragm plate 4 provided on the side of the lens array 1 facing the subject has a curved or inclined structure like the lens array.

  The optical image of the subject imaged by the imaging apparatus passes through each hole of the aperture plate 4, is condensed by each lens of the lens array 1, passes through the triangular prism 7, and passes through the triangular prism 7. Incident perpendicularly to each region. In other words, the sensor light receiving unit 6 acquires a compound eye image including a set of single-eye images corresponding to the number of lenses in the lens array 1 while preventing occurrence of aberration and without deteriorating optical performance. The stroke of the light beam between adjacent lenses is prevented by a partition provided on the light shielding plate 5.

  According to the present embodiment, by combining the curved lens array 1 and the triangular prism, it is brighter, has less MTF deterioration, and is more reliable than a conventional wide-angle lens using a plurality of lenses. A wide-angle image can be acquired. Note that how much the lens array 1 is curved may be determined depending on how wide the lens array 1 is desired.

  FIG. 6 shows a cross-sectional view of another embodiment of the imaging apparatus according to the present invention. 6, the same parts as those in FIG. 4 are denoted by the same reference numerals. Here, the configuration and arrangement of the lens array 1, the diaphragm plate 4, the light shielding plate 5 and the like are the same as in FIG. 4, but in this embodiment, the hologram element 8 is used as means for bending the light beam instead of the triangular prism of FIG. Is provided.

  The hologram element can change the direction of the light beam by providing a concavo-convex shape on the flat plate, and can be made thinner in the optical axis direction than the triangular prism. Is possible.

  Also in this embodiment, it is possible to obtain a wide-angle compound eye image that is brighter, has less MTF deterioration, and is more reliable than a wide-angle lens using a plurality of conventional lenses. Further downsizing is possible.

DESCRIPTION OF SYMBOLS 1 Lens array 2 Lens holder 3 Board | substrate 4 Diaphragm plate 5 Light-shielding plate 6 Sensor light-receiving part (imaging element)
7 Triangular prism 8 Hologram element

Japanese Patent Laid-Open No. 2003-143459 JP 2009-201008 A

Claims (4)

Each of the subjects that is substantially imaged by each of a lens array in which a plurality of lenses are arranged in an array and a plurality of lenses that are provided on the image plane side of the lens array. In an imaging apparatus having an imaging element that captures a compound eye image that is a set of eye images,
The lens array is curved convexly with respect to the subject side, and the optical axis of each lens of the lens array is perpendicular to the light receiving surface of the image sensor between the lens array and the image sensor. An image pickup apparatus characterized in that means for bending a light beam is provided.   The imaging device according to claim 1, wherein an end lens of the lens array is inclined outward.   3. The imaging apparatus according to claim 1, wherein the means for bending the light beam comprises a triangular prism whose surface corresponding to the lens array is curved in a concave shape opposite to the lens array.   The imaging apparatus according to claim 1 or 2, wherein the means for bending the light beam comprises a hologram element having a concavo-convex shape on a surface facing the lens array.

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