JP2012199633A - Imaging element and imaging apparatus provided with the same - Google Patents

Abstract

An image pickup apparatus for 3D image pickup that is small in size and low in price and easy in alignment work of an image pickup optical system is provided.
An imaging apparatus includes an imaging element for 3D image imaging in which light from an object surface is collected. The imaging device has a microlens array 51 and at least a pair of light receiving portions 52L and 52R for each of the microlenses 51a of the microlens array 51, and receives light BR incident on the microlens array 51 from the right side. The light BL received by the unit 52L and incident on the microlens array 51 from the left side is received by the light receiving unit 52R.
[Selection] Figure 2

Description

  The present invention relates to an imaging device that captures an image with parallax for 3D display, and an imaging device including the imaging device.

  The 3D method generally arranges two cameras composed of an imaging optical system and an imaging element in the left-right direction to photograph two images (right image and left image) with different parallaxes, and the right image and the left image are Displayed on a 3D TV or 3D display, and using polarized or time field sequential glasses, the right image can be seen only by the left eye and the left image can be seen only by the left eye, thereby synthesizing the video in the brain. It has a three-dimensional effect.

  As a method for capturing two images with different parallaxes for 3D image display, unlike the above, there is a method in which object light captured by one imaging optical system is divided into two by the imaging optical system (for example, Patent Document 1). ). 9A is a diagram for explaining the 3D display imaging device disclosed in Patent Document 1, and FIG. 9B is a view in the direction of the arrow A of the diaphragm 102 of the 3D imaging device in FIG. 9A. It is.

  In the imaging optical system of Patent Document 1, as shown in FIG. 9A, the right side of the figure among the light beams incident on the primary optical system 101 in the imaging optical system from one point on the object plane (not shown). The light BR traveling through reaches the right side 102R of the stop 102 of the imaging optical system. Similarly, the light BL traveling on the left side of the figure reaches the left side 102L of the stop 102 of the imaging optical system. The same applies to not only the object light on the optical axis shown in the figure but also off-axis light (for example, light traveling on the right side with respect to the principal ray direction reaches the right side 102R of the stop 102 of the imaging optical system). That is, as shown in FIG. 9B, when the diaphragm 102 of the imaging optical system is divided into a left region 102a and a right region 102b, a light beam traveling in the left direction from the object is present in the left region 102a, and an object is present in the right region 102b. Since the luminous fluxes traveling in the right direction from each other gather, light having different parallax gathers in the left region 102a and the left region 102b.

  The light that has passed through the left region 102a of the stop 102 is reflected to the left by the prism 103, is further reflected by the reflection mirror 104a, passes through the imaging lens 105a, and is received by the image sensor 106a. On the other hand, the light that has passed through the right region 102b of the diaphragm 102 is reflected to the right by the prism 103, further reflected by the reflecting mirror 104b, transmitted through the imaging lens 105b, and received by the image sensor 106b different from the image sensor 106a. Is done. In this way, two images with different parallax are taken.

Japanese Unexamined Patent Publication No. 6-194581

  However, in the imaging device for 3D display disclosed in Patent Document 1, two images having different parallax are obtained from two imaging elements, and a secondary optical system for forming an image on the imaging element after being separated by a prism. Two are required. For this reason, the entire imaging optical system is enlarged, and at the same time, a complicated optical system is required. Moreover, the unit cost of the optically polished high-accuracy prism is high, and the manufacturing cost is high due to the large number of parts. Furthermore, since high-precision alignment work of optical axes such as a prism, a secondary optical system, and an image sensor is required, productivity is low.

  The present invention has been made in view of such circumstances, and an image pickup device for 3D display that can reduce the size and cost of an image pickup device for 3D display and that can easily perform an alignment operation of an image pickup optical system, and the image pickup. An object of the present invention is to provide an imaging device including an element.

  In order to solve the above-mentioned problems, a first technical means of the present invention is an image pickup device for 3D image pickup in which light from an object surface is collected, and has a microlens array, and the microlens array Each of the microlenses has at least a pair of light receiving portions, and receives light incident on the microlens array from one side with respect to a predetermined direction, and receives the light with one of the pair of light receiving portions and the other with respect to the predetermined direction. The light incident on the microlens array from the side is received by the other of the pair of light receiving portions.

  According to a second technical means of the present invention, in the first technical means, the microlens array collects light incident on the incident surface side of the microlens from the predetermined direction for each microlens. An inclined surface having at least two different angles that guides both of the pair of light receiving portions by separating the light collected by the convex portion in at least two directions on the emission surface side of the microlens. It is characterized by having.

  According to a third technical means of the present invention, in the second technical means, a top portion which is a division position of at least two different inclined surfaces arranged on the exit surface side of the microlens is an incident surface of the microlens. It is located on the optical axis of the said convex part arrange | positioned at the side.

  According to a fourth technical means of the present invention, in the third technical means, the inclined surfaces of at least two different angles arranged on the exit surface side of the microlens are convex curved surfaces on the light incident side. It is characterized by.

  According to a fifth technical means of the present invention, in the third technical means, the inclined surfaces of at least two different angles arranged on the exit surface side of the microlens are concave curved surfaces on the light incident side. It is characterized by.

  A sixth technical means of the present invention is an imaging apparatus comprising: the image sensor of any one of the first to fifth technical means; and an optical system that guides light from an object plane to the image sensor.

  According to the present invention, it is possible to provide an image pickup apparatus for 3D display that is small in size and low in price and can easily perform an alignment operation of an image pickup optical system.

It is a figure which shows the structural example of the principal part of the imaging device of this invention. It is a figure which shows the structural example of the image pick-up element of the imaging device of FIG. It is a figure which shows the other structural example of an image pick-up element. It is a figure which shows another structural example of an image pick-up element. It is a figure which shows another structural example of an image pick-up element. It is a figure which shows the structural example of the principal part of the imaging device for colors of this invention. It is a figure which shows the structural example of the image pick-up element using the light receiving element of a Bayer arrangement. It is a figure which shows the other structural example of the image pick-up element using the light receiving element of a Bayer arrangement. It is a figure explaining the conventional imaging device.

The image pickup apparatus for 3D display according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram illustrating a configuration of a main part of an imaging apparatus according to the present invention, and FIG. 2 is a diagram illustrating a configuration of an imaging element of the imaging apparatus in FIG.
The image pickup apparatus for 3D image pickup according to the present invention includes a primary optical system 2, a diaphragm 3, a secondary optical system 4, and an image sensor 5 as illustrated by reference numeral 1 in FIG. 1.
The primary optical system 2 is composed of lenses 2 a to 2 d and condenses a light beam from one point on an object surface (not shown) on the diaphragm 3.
The secondary optical system 4 is composed of lenses 4 a to 4 c, and forms an image on the image sensor 5 with the light that is narrowed down by the stop 3 by the primary optical system 2. In the present embodiment, the imaging optical system is a so-called image-side telecentric optical system in which a chief ray passing through the center of the stop 3 enters the imaging device 5 perpendicularly.

  The imaging element 5 is disposed in the vicinity of the focal position of an imaging optical system composed of a primary optical system and a secondary optical system. As shown in FIG. 2, a convex microlens 51a having a positive power is emitted from the light. A microlens array 51 formed on the incident surface side; a light receiving element 52 having a pair of light receiving portions 52L and 52R for one microlens 51a in the vicinity of the focal plane of each microlens 51a; A cover glass 53 for protecting the light receiving element 52 is provided.

As shown in FIGS. 1 and 2B, in the 3D imaging apparatus 1, the center of the diaphragm surface of the diaphragm 3 out of the light flux incident on the apparatus 1 from one point on the object plane (not shown). The principal ray BC passing through is incident on the image sensor 5 from a predetermined direction (in this example, from the vertical direction), and this principal ray BC is a boundary between the light receiving part 52L and the light receiving part 52R of the light receiving element 52 of the image pickup element 5. Is incident on.
As shown in FIGS. 1 and 2A, in the 3D imaging apparatus 1, the light BR emitted toward the right side of the principal ray BC out of the light flux reaches the right side of the stop surface of the stop 3. Then, the light enters the imaging element 5 at an angle from the right side, and enters the light receiving unit 52L on the left side of the light receiving element 52 of the element 5.
In addition, as shown in FIGS. 1 and 2C, in the 3D imaging apparatus 1, the light BL emitted from the principal beam BC to the left side, which has a parallax different from the light BR, out of the luminous flux is It reaches the left side of the diaphragm surface of the diaphragm 3, enters the imaging element 5 with an angle from the left side, and enters the light receiving part 52 </ b> R on the right side of the light receiving element 52 of the element 5.
In the 3D imaging device 1, the image obtained by the left light receiving unit 52L of the light receiving element 5 and the image obtained by the right light receiving unit 52R are processed as different images, and the parallax for stereoscopic display is processed. Two images are generated.

Since the 3D imaging apparatus 1 uses only one imaging element to generate two images having different parallaxes, the cost can be reduced. In addition, since only one imaging optical system is required, high-precision alignment work of the optical axis is facilitated, the productivity is high, the apparatus can be miniaturized, and the cost can be further reduced. Furthermore, since the optically polished high-precision prism used in the apparatus disclosed in Patent Document 1 is not necessary, the cost can be reduced.
The 3D imaging device 1 can also be used for 2D display. In this case, the sum of the pixel value in the left light receiving unit 52L and the pixel value in the right light receiving unit 52R is used as one pixel value. It is preferable. This is because the sensitivity characteristic of the image sensor can be improved.

FIG. 3 is a diagram illustrating another example of the imaging element. The same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.
3, a convex microlens 51a having a positive power is formed on the incident surface side of the microlens array 61, as shown in FIG. The light BR incident on the image pickup device 6 at an angle from the right side enters the light receiving portion 52L on the left side of the light receiving device 52, and as shown in FIG. Then, the light BL incident at an angle from the left side enters the right light receiving part 52R of the light receiving element 52.

However, unlike the image pickup device 5 of FIG. 2, the image pickup device 6 has a pair of two prism-shaped inclined surfaces 61a at different angles on the exit surface side of the microlens array 61, as shown in FIG. As shown, the light BC incident substantially perpendicular to the image sensor 6 is also incident on the light receiving portions 52L and 52R of the light receiving element 52 of the image sensor 6.
In the example of FIG. 2, the light BC that passes through the center of the stop surface of the diaphragm, that is, the center of the pupil and is perpendicularly incident on the image sensor cannot be received by the light receiving unit of the image sensor 5, but is lost. Since light can be received, loss of light can be reduced. Further, in the example of FIG. 2, the interval between the pixels of the image sensor becomes small and the high manufacturing accuracy of the semiconductor manufacturing process rule is required, but the example of FIG. 3 is also advantageous in the process of manufacturing the image sensor.
When the positions of the light receiving unit 52L and the light receiving unit 52R are symmetric with respect to the optical axis of the microlens 51a, the division position of the inclined surface 61a at two different angles, that is, the top of the inclined surface 61a is on the optical axis of the microlens 51a. It is good to do. The light BC incident perpendicularly to the image sensor 6 can be evenly received by the light receiving part 52L and the light receiving part 52R.

FIG. 4 is a diagram illustrating another example of the image sensor. The same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted.
4 has a microlens 51a formed on the incident surface side of the microlens array 71 as shown in FIG. 4A, like the image sensor 6 in FIG. On the other hand, the light BR incident at an angle from the right side enters the left light receiving portion 52L of the light receiving element 52, and as shown in FIG. BL is incident on the light receiving part 52R on the right side of the light receiving element 52. The image sensor 7 has a pair of two inclined surfaces 71a having different angles on the emission surface side of the microlens array 71, and is substantially perpendicular to the image sensor 7 as shown in FIG. The incident light BC is also incident on the light receiving portions 52L and 52R of the light receiving element 52 of the image sensor 7.
However, unlike the image pickup element 6 of FIG. 3, the image pickup element 7 is not an end face of a pair of two inclined surfaces with different angles arranged on the exit surface side of the microlens array 71. It has a concave shape. Thereby, since the focal distance of the whole microlens becomes short, a condensing diameter becomes small and it becomes possible to improve the condensing performance to the light-receiving parts 52L and 52R.

FIG. 5 is a diagram illustrating another example of the image sensor. The same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted.
5, as with the image sensor 6 in FIG. 3, the microlens 51 a is formed on the incident surface side of the microlens array 81 as shown in FIG. On the other hand, the light BR incident at an angle from the right side enters the left light receiving portion 52L of the light receiving element 52 and enters the imaging element 8 at an angle from the left side as shown in FIG. 5C. BL is incident on the light receiving part 52R on the right side of the light receiving element 52. The image sensor 7 has a pair of two inclined surfaces 81a at different angles on the exit surface side of the microlens array 81, and is substantially perpendicular to the image sensor 8 as shown in FIG. The incident light BC is also incident on the light receiving portions 52L and 52R of the light receiving element 52 of the image sensor 8.
However, unlike the image sensor 6 of FIG. 3, the image sensor 8 has a pair of inclined surface end surfaces of two different angles arranged on the exit surface side of the microlens array 81 on the light incident side instead of a flat surface. It has a convex shape. Thereby, since the focal distance can be increased and the distance to the light receiving parts 52L and 52L can be increased, it is possible to improve the separability of light to the light receiving part 52L and the light receiving part 52R.
In the microlens array of the example of FIGS. 4 and 5, the end surface on the exit surface side is aspherical, so that aberration on the exit surface side can be reduced as compared with a planar shape.

FIG. 6 is a diagram showing a configuration of a main part of the color imaging apparatus for 3D display according to the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
The 3D color image pickup apparatus 1 ′ shown in the figure has a color separation prism 9 provided with reflection surfaces by dichroic mirrors 91 and 92 inside, and colors light that has passed through the image pickup optical systems 2 and 4 in different light paths for RGB. Decompose. Any one of the above-described imaging elements 5 (5R, 5G, 5B), 6 (6R, 6G, 6B), 7 (7R, 7G, 7B), 8 (8R, 8G, 8B) in the color-separated RGB optical path Since an RGB image can be picked up by arranging the two, it is possible to pick up two RGB images with parallax by combining the RGB images.

In the above example, the light receiving element of the imaging element is for monochrome, but a color light receiving element represented by a Bayer array of light receiving elements may be used.
FIG. 7A is a diagram illustrating an example of an image sensor using a Bayer array of light receiving elements, and FIG. 7B is an enlarged view in the direction of arrow X in FIG. 7A. FIG. 8 is a diagram showing another example of the lens shape of the microlens array in the case of using a Bayer array of light receiving elements.

  The image sensor 10 in FIG. 7 includes an image sensor 11 having a Bayer array. A Bayer array imaging device generally creates an image of one pixel from four light receiving portions with color filters. Therefore, in this case, two sets of light receiving portions 11L and 11R may be arranged in one microlens 51a, with four light receiving portions RGGB serving as one set of light receiving portions. The light incident on the image sensor 10 from the right side enters the light receiving unit 11L on the left side of the light receiving element 11, and the light incident on the image sensor 10 from the left side from the left side receives the light receiving element 11. In this case, the light is incident on the right light receiving portion 11R. Similarly, when the shape of the microlens is the shape shown in FIGS. 3, 4, and 5, it is possible to use an image sensor having a Bayer array.

  As shown in FIG. 8, the shape of the microlens 51a ′ of the microlens array 51 ′ may be asymmetrical in length and breadth when viewed from the vertical direction with respect to the incident surface. As a result, the pitches of the light receiving portions 11L and 11R in the vertical direction and the horizontal direction can be made the same.

  In the present invention, an example is shown with an image-side telecentric imaging optical system, but the image-side telecentric is not necessarily required. In order to reduce the imaging optical system, it is common that the incident angle to the imaging device increases as it goes from the center to the periphery. In this case, the optical axis of the microlens is offset with respect to the light receiving portion of the imaging device. Thus, the amount of light in the periphery can be secured. Thus, it is possible to cope with the case where the principal ray around the image plane has an angle. In that case, the light of the right image and the left image can be evenly separated by inclining the angle of the peripheral prism surface by the inclination of the principal ray.

DESCRIPTION OF SYMBOLS 1,1 '... 3D imaging device, 2 ... Primary optical system, 3 ... Diaphragm, 4 ... Secondary optical system, 5, 6, 7, 8, 10 ... Image sensor, 51, 51', 61, 71, 81: microlens array, 52, 11: light receiving element, 61a, 71a, 81a ... inclined surface, 9 ... color separation prism.

Claims (6)

An image sensor for 3D image capturing in which light from an object surface is collected,
A microlens array and at least a pair of light receiving portions for each of the microlenses of the microlens array, and light incident on the microlens array from one side with respect to a predetermined direction. An image pickup device that receives light on one side and receives light incident on the microlens array from the other side with respect to the predetermined direction at the other of the pair of light receiving units.   The microlens array has, for each microlens, a convex portion for condensing light incident on the incident surface side of the microlens from the predetermined direction, and at least two lights collected by the convex portion are collected. 2. The image pickup device according to claim 1, further comprising at least two inclined surfaces having different angles, which are guided to both of the pair of light receiving units by being separated in a direction, on an emission surface side of the microlens.   The apex that is the dividing position of at least two different inclined surfaces arranged on the exit surface side of the microlens is located on the optical axis of the convex portion arranged on the entrance surface side of the microlens. The imaging device according to claim 2, wherein   The imaging device according to claim 3, wherein at least two inclined surfaces having different angles arranged on the exit surface side of the microlens are convex curved surfaces on the light incident side.   The imaging device according to claim 3, wherein at least two inclined surfaces having different angles arranged on the emission surface side of the microlens are concave curved surfaces on the light incident side.   An imaging device comprising: the imaging device according to claim 1; and an optical system that guides light from an object surface to the imaging device.

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