JP2019138973A - Image capturing device - Google Patents

Abstract

An object of the present invention is to ensure the optical performance of a lens and to suppress the enlargement of an image pickup apparatus.
An imaging apparatus according to the present invention includes a first lens on which light of an object is incident, a reflecting portion that bends an optical axis by reflecting light that has passed through the first lens, and a bending portion that is bent by the reflecting portion. A lens unit having an image pickup unit disposed on the optical axis; and a drive unit that rotates the lens unit.
[Selection] Figure 4

Description

  The present invention relates to an imaging apparatus.

Conventionally, a camera unit for imaging a subject is covered with a housing such as a dome and supported so as to be rotatable around a pan axis and a tilt axis, and the direction of the camera unit is changed to a desired shooting direction by a user. An imaging device that can take a picture is known. In such an imaging apparatus, there is a demand for higher performance and smaller size of the camera unit. However, if the performance of a photographic lens is increased, such as an increase in zoom magnification or an increase in the size of an image sensor, the optical path length of the photographic lens increases. As a result, the entire imaging apparatus including the camera unit and the casing covering the camera unit is increased in size, which is a factor that hinders downsizing of the imaging apparatus.
The imaging device disclosed in Patent Document 1 can realize a small panning mechanism by rotating a bending optical system in the optical axis direction, and further tilting not only the reflecting surface but also the lens in order to reduce the size of the bending portion. To drive. In addition, the image pickup apparatus of Patent Document 1 is configured to correct an automatic panning direction shift due to video tilt, and has a function of automatically returning to an initial composition after manual panning.

JP 2009-42771 A

  However, in the imaging apparatus disclosed in Patent Document 1, it is necessary to drive the reflecting surface and the predetermined lens or the predetermined lens group independently at different rotation angles. For this reason, the mechanism becomes complicated, and it is difficult to maintain the optical axis of each lens or lens group at a desired accuracy in any photographing direction, and it is difficult to maintain the optical performance of the lens.

  It is an object of the present invention to ensure the optical performance of a lens and suppress the enlargement of an image pickup apparatus.

  An image pickup apparatus according to the present invention includes a first lens on which light of a subject is incident, a reflection unit that bends an optical axis by reflecting light transmitted through the first lens, and an optical axis that is bent by the reflection unit. A lens unit having an image pickup element disposed on the image sensor; and a driving unit that rotates the lens unit.

  According to the present invention, it is possible to secure the optical performance of the lens and suppress the enlargement of the imaging device.

It is a perspective view which shows an example of an imaging device. It is sectional drawing which shows an example of an imaging device. It is a disassembled perspective view which shows an example of a lens-barrel. It is sectional drawing which shows an example of a lens-barrel. It is sectional drawing which shows an example of the lens-barrel used as a comparative example. It is sectional drawing etc. which show an example of a lens-barrel.

First, the outer shape of the imaging device 10 will be described with reference to FIG. FIG. 1 is a perspective view illustrating an example of the imaging apparatus 10. The imaging device 10 includes a dome 11 and a case 12 as exterior parts. The dome 11 is a hemispherical cover that covers a lens barrel 21 described later, and is made of transparent or translucent plastic. The case 12 has a cylindrical shape and accommodates at least a pan unit 25 described later. The dome 11 and the case 12 are a housing of the imaging device 10.
The imaging device 10 is used by attaching the opposite side of the case 12 to the dome 11 to a ceiling or a wall. In addition, the imaging device 10 may be installed and used on the ceiling or wall by at least part of the case 12 being embedded in the ceiling or wall.

Next, the configuration of the imaging device 10 will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating an example of the imaging device 10. The imaging device 10 includes a lens barrel 21, an inner cover 22, a camera case 23, a tilt unit 24, and a pan unit 25 inside a dome 11 and a case 12 that are exterior parts.
The lens barrel 21 is a barrel having a plurality of lenses as will be described later. The lens barrel 21 is an example of a lens unit.
The inner cover 22 is supported by the pan unit 25 and hides internal mechanisms other than the lens barrel 21. The inner cover 22 has a hole 22a corresponding to the imaging range of the lens barrel 21 in the range in which the lens barrel 21 rotates in the tilt direction.

The camera case 23 holds the lens barrel 21 inside and covers the lens barrel 21 so as to expose a first lens group L1 described later.
The tilt unit 24 supports the camera case 23 including the lens barrel 21 so as to be rotatable in the tilt direction. More specifically, the tilt unit 24 supports the camera case 23 including the lens barrel 21 so as to be rotatable in both directions of the tilt direction within a predetermined range of the tilt direction. The tilt unit 24 has a tilt drive unit including a stepping motor (not shown) and the like, and electrically drives the camera case 23 including the lens barrel 21 in the tilt direction.
The pan unit 25 supports the tilt unit 24 so as to be rotatable in the pan direction. More specifically, the pan unit 25 supports the tilt unit 24 so that it can rotate in both directions in the pan direction within a predetermined range in the pan direction. The pan unit 25 may support the tilt unit 24 so that it can rotate 360 ° in the pan direction. The pan unit 25 includes a pan driving unit including a stepping motor (not shown) and the like, and electrically drives the tilt unit 24 in the pan direction. The tilt unit 24 and the pan unit 25 are an example of a drive unit that rotates the lens barrel 21.

Next, the configuration of the lens barrel 21 will be described with reference to FIG. FIG. 3 is an exploded perspective view showing an example of the lens barrel 21.
The lens barrel 21 includes a first group lens L1, a first group barrel 31, a second group lens L2, a second group barrel 32, an aperture unit 33, a third group lens L3, and a third group lens. A group barrel 34, a prism 35, a fourth group lens L4, and a fourth group barrel 36 are provided. The lens barrel 21 includes a filter L5, a filter holding frame 37, a sensor unit 38, and a sensor holder 39.

The first group lens L1 is a lens on which light of an object enters. The optical axis of the first group lens L1 is defined as a first optical axis AX1. The first group lens L1 is an example of a first lens. The first group lens barrel 31 holds the first group lens L1. The first group barrel 31 is an example of a first holding unit.
The second lens group L2 moves in the direction of the first optical axis AX1 along the first optical axis AX1, and performs a zooming operation. The optical axis of the second group lens L2 is the first optical axis AX1. The second group lens L2 is disposed on the opposite side of the subject with the first group lens L1 in between. The second group lens barrel 32 holds the second group lens L2.
The diaphragm unit 33 drives the diaphragm blades to change the aperture diameter of the diaphragm.
The third group lens L3 is disposed on the opposite side of the first group lens L1 with the second group lens L2 interposed therebetween. The optical axis of the third group lens L3 is the first optical axis AX1. The third group barrel 34 holds the third group lens L3.

The prism 35 bends the optical axis by reflecting the light transmitted through the first lens unit L1 by the reflecting surface 35a shown in FIG. The optical axis before being bent by the prism 35 is the first optical axis AX1. The optical axis after being bent by the prism 35 is defined as a second optical axis AX2. The prism 35 is disposed on the opposite side of the second group lens L2 with the third group lens L3 interposed therebetween. The prism 35 bends the optical axis by 90 °. For this reason, the angle formed by the first optical axis AX1 and the second optical axis AX2 is 90 °. The prism 35 is an example of a reflection unit.
The fourth group lens L4 moves in the direction of the second optical axis AX2 along the second optical axis AX2, and performs a focusing operation. The optical axis of the fourth group lens L4 is the second optical axis AX2. The fourth group lens L4 is an example of a second lens. The fourth group lens barrel 36 holds the fourth group lens L4.

The filter L5 is an IR cut filter (infrared cut filter), is movable in a direction perpendicular to the second optical axis AX2, and can be inserted into and removed from the second optical axis AX2. The infrared light is shielded by inserting the filter L5 into the optical path. Moreover, infrared light permeate | transmits because the filter L5 is extracted from an optical path. The filter holding frame 37 holds the filter L5.
The sensor unit 38 has a printed circuit board on which an image sensor (photoelectric conversion element) is mounted, and a metal plate attached to the printed circuit board. A CCD (Charge-Coupled Device) image sensor, a CMOS (complementary MOS) image sensor, or the like is used as the imaging element. The sensor unit 38 is disposed on the opposite side of the prism 35 with the fourth group lens L4 interposed therebetween. The filter L5 is positioned between the fourth group lens L4 and the sensor unit 38 in a state where the filter L5 is inserted in the second optical axis AX2. The sensor unit 38 is an example of an imaging unit. The sensor holder 39 holds the sensor unit 38. The sensor holder 39 is an example of a second holding unit.

The lens barrel 21 includes a fixed barrel 41, a rear barrel 42, various guide bars 43 to 46, stepping motors 47 and 48, a galvanometer 49, and a lens substrate 50.
In the fixed barrel 41, the front end (end on the subject side) fixes and holds the first group barrel 31 and the rear end is fixed to the rear barrel 42 in order to fix the first group lens L1 at a predetermined position. Are combined.
Both ends of the first guide bar 43 and the second guide bar 44 are held by the fixed barrel 41 and the rear barrel 42, and support the second group barrel 32 so as to be movable in the direction of the first optical axis AX1. To do.
Both ends of the third guide bar 45 and the fourth guide bar 46 are held by the rear barrel 42 and the sensor holder 39, and support the fourth group barrel 36 movably in the second optical axis AX2 direction. .
The stepping motor 47 is used as a drive source of a drive mechanism that moves the second group barrel 32 and is fixed to the fixed barrel 41.
The stepping motor 48 is used as a drive source of a drive mechanism that moves the fourth group barrel 36 and is fixed to the rear barrel 42. The stepping motor 48 is an example of a moving unit that moves the fourth group lens L4.
The galvanometer 49 is used as a drive source for the filter holding frame 37 and is fixed to the rear barrel 42. The galvanometer 49 is an example of a moving unit that moves the filter L5.
The lens substrate 50 is provided with a circuit, has a function as a control means for comprehensively controlling the lens barrel 21, and is fixed to the rear barrel 42.

Next, the lens barrel 21 will be described with reference to FIG. FIG. 4 is a cross-sectional view showing an example of the lens barrel 21.
A point 60 in FIG. 4 is an intersection of a rotation axis when the lens barrel 21 rotates in the pan direction and a rotation axis when the lens barrel 21 rotates in the tilt direction. The length from the point 60 to the end of the first group barrel 31 on the subject side is defined as SR. Then, when considering a virtual sphere 61 that is a virtual sphere having the point 60 as the center point and the SR as the radius, as shown in FIG. 4, the lens barrel 21 includes a part of the first group barrel 31 that is virtual. The shape included in the phantom sphere 61 is in contact with the surface of the sphere 61. The first optical axis AX1 passes through the point 60.

  Further, in the direction of the first optical axis AX1, the lens substrate 50 and the stepping motor 48 of FIG. 3 are arranged in a region S1 between the phantom sphere 61 and the rear barrel 42. Therefore, the lens substrate 50 and the stepping motor 48 are disposed inside the phantom sphere 61 on the opposite side of the first group lens L1 with the prism 35 interposed therebetween. In addition, a galvanometer 49 is disposed in a region S2 surrounded by the first optical axis AX1, the second optical axis AX2, and the phantom sphere 61.

  Next, the first optical path length LT1 that is the optical path length of the lens barrel 21 of the present embodiment will be described. The first optical path length LT1 is the optical path length from the apex of the lens surface closest to the subject of the first group lens L1 to the sensor unit 38 through the first optical axis AX1 and the second optical axis AX2. It is. In FIG. 4, the first optical path length LT1 is represented by “X1 + X2 + Y”. Here, X1 is the optical path length from the vertex of the lens surface closest to the subject of the first group lens L1 to the point 60 through the first optical axis AX1. X2 is an optical path length from the point 60 to the reflecting surface 35a of the prism 35 through the first optical axis AX1. Y is the optical path length from the reflecting surface 35a of the prism 35 to the sensor unit 38 through the second optical axis AX2. In this embodiment, “X2 = 0.4 × SR”.

  Next, the second optical path length LT2 to be compared with the first optical path length LT1 will be described. The second optical path length LT2 is an optical path length in the lens barrel 21a as a comparative example. Therefore, a difference between the lens barrel 21a as a comparative example and the lens barrel 21 of the present embodiment will be described with reference to a cross-sectional view of the lens barrel 21a shown in FIG. The lens barrel 21a does not have the prism 35 and the optical axis is not bent. For this reason, the optical axis of the lens barrel 21a is only the first optical axis AX1. The sensor unit 38 of the lens barrel 21a is disposed on the first optical axis AX1. Further, the sensor unit 38 of the lens barrel 21 a is arranged so that a part thereof is in contact with the phantom sphere 61. The lens barrel 21a as a comparative example is included in the phantom sphere 61, like the lens barrel 21 of the present embodiment. As shown in FIG. 5, the second optical path length LT2, which is the optical path length of the lens barrel 21a as a comparative example, is the first from the apex of the lens surface closest to the subject side of the first group lens L1. This is the optical path length from the optical axis AX1 to the sensor unit 38. Such a second optical path length LT2 is applied to the sensor unit 38 from the first lens group L1 through the first optical axis AX1 when the following assumption is made for the lens barrel 21 of the present embodiment. It is the optical path length. That is, it is assumed that the prism 35 does not exist, and further, from the first group lens L1 in the case where it is assumed that the sensor unit 38 is disposed inside the phantom sphere 61 and on the first optical axis AX1, This is the optical path length from the optical axis AX1 to the sensor unit 38.

  When the first optical path length LT1 and the second optical path length LT2 are compared, “LT1 / LT2 = 1.12” is obtained. Therefore, the lens barrel 21 of the present embodiment can increase the optical path length by 12% compared to the lens barrel 21a as a comparative example. By increasing the optical path length, it is possible to achieve higher performance of the photographing lens such as higher zoom magnification and larger imaging element.

  As described above, the imaging apparatus 10 includes the lens barrel 21, the tilt unit 24 that rotates the lens barrel 21, and the pan unit 25. The lens barrel 21 includes a prism 35 that bends the optical axis by reflecting the light that has passed through the first lens group L1, and a sensor unit 38 that includes an imaging device disposed on the folded optical axis. Therefore, compared with the case where the prism 35 is not provided, the optical path length can be increased regardless of the direction of imaging without increasing the size of the lens barrel 21. Further, the imaging apparatus 10 can increase the optical path length without having a complicated mechanism like the imaging apparatus of Patent Document 1. Therefore, the optical performance of the lens can be ensured, and the increase in size of the imaging device can be suppressed. And the imaging device 10 which enabled it to make a lens high-performance with a simple structure, without enlarging the housing of the dome 11 can be provided. Further, the lens barrel 21 is provided with the members constituting the lens barrel 21 so as to be included in the phantom sphere 61. Therefore, the enlargement of the lens barrel 21 can be suppressed.

(Other embodiments)
In the above embodiment, the radius SR of the phantom sphere 61 is the length from the point 60 to the end of the first group barrel 31 on the subject side. The lens barrel 21 has a shape included in the phantom sphere 61 such that a part of the first group barrel 31 is in contact with the surface of the phantom sphere 61.
However, the radius SR of the phantom sphere 61 may be a length from the point 60 to a part of the first group lens L1. A part of the first group lens L1 is, for example, the apex of the lens surface closest to the subject of the first group lens L1. Further, the radius SR of the phantom sphere 61 may be a length from the point 60 to a part of the sensor unit 38. The radius SR of the phantom sphere 61 may be a length from the point 60 to a part of the sensor holder 39. In any case, the lens barrel 21 has a shape included in the phantom sphere 61 such that a part of the lens barrel 21 is in contact with the surface of the phantom sphere 61.

Here, the first optical path length LT1 that is the optical path length of the lens barrel 21b as a modification of the present embodiment will be described. In the lens barrel 21b, the first lens group L1 and the sensor unit 38 are in contact with the surface of the phantom sphere 61, as shown in the sectional view of the lens barrel 21b in FIG. The radius SR of the phantom sphere 61 here is the length from the point 60 to the vertex of the lens surface closest to the subject of the first group lens L1. Further, the length W of the side of the sensor unit 38 of the lens barrel 21b is set to “0.3 × SR”. In the lens barrel 21b, the optical axis is bent 90 °. For this reason, the angle formed by the first optical axis AX1 and the second optical axis AX2 is 90 °.
The first optical path length LT1 of the lens barrel 21b is the first optical axis AX1 from the apex of the lens surface closest to the subject of the first group lens L1, similarly to the first optical path length LT1 of the above-described embodiment. And the optical path length from the second optical axis AX2 to the sensor unit 38. In FIG. 6A, the first optical path length LT1 of the lens barrel 21b is represented by “X1 + X2 + Y” as in the above embodiment.

  Next, the second optical path length LT2 to be compared with the first optical path length LT1 of the lens barrel 21b will be described. The second optical path length LT2 is an optical path length in the lens barrel 21c as a comparative example. As shown in the sectional view of the lens barrel 21c in FIG. 6B, the lens barrel 21c as a comparative example does not have the prism 35 and the optical axis is not bent. For this reason, the optical axis of the lens barrel 21c is only the first optical axis AX1. The sensor unit 38 of the lens barrel 21c is disposed on the first optical axis AX1. Further, the sensor unit 38 of the lens barrel 21 a is arranged so that a part thereof is in contact with the phantom sphere 61. The lens barrel 21c as a comparative example is included in the phantom sphere 61 in the same manner as the lens barrel 21b. The second optical path length LT2, which is the optical path length of the lens barrel 21c as such a comparative example, is as shown in FIG. 6B from the apex of the lens surface closest to the subject side of the first group lens L1. This is the optical path length from the first optical axis AX1 to the sensor unit 38.

Next, regarding the relationship between the first optical path length LT1 of the lens barrel 21b and the second optical path length LT2 of the lens barrel 21c as a comparative example, refer to the optical path length ratio graph of FIG. explain. The horizontal axis of the optical path length ratio graph is the bending position representing the optical path length from the point 60 to the time when the optical axis is bent in the lens barrel 21b, and is a value represented by “X2 / SR”. The vertical axis of the optical path length ratio graph is the optical path length ratio, which is a value represented by “LT1 / LT2”. In the optical path length ratio graph of FIG. 6C, the optical path length ratio becomes maximum when “X2 / SR” as the bending position is about 5.7.
Thus, by appropriately determining the bending position, it is possible to lengthen the optical path length of the lens without increasing the size of the housing of the dome 11, and to provide the imaging device 10 capable of improving the performance of the lens. can do.

In the above embodiment, the prism 35 bends the optical axis by 90 °. However, the angle of the optical axis by which the prism 35 bends may be other than 90 °. Further, instead of the prism 35, a member such as a mirror that reflects light may be used.
Although the present invention has been described together with the embodiments, the above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention is interpreted in a limited manner by these. It must not be. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

  As mentioned above, according to embodiment mentioned above, the optical performance of a lens can be secured and the enlargement of an imaging device can be controlled.

DESCRIPTION OF SYMBOLS 10 Imaging device 21 Lens barrel 35 Prism 38 Sensor unit AX1 1st optical axis AX2 2nd optical axis L1 1st group lens

Claims (12)

A first lens on which light of an object is incident; a reflecting portion that bends the optical axis by reflecting the light that has passed through the first lens; and an imaging device that is disposed on the optical axis that is bent by the reflecting portion An imaging unit having: a lens unit having:
A drive unit for rotating the lens unit;
An imaging apparatus having The lens unit is a shape included in a virtual sphere centered on a point on the rotation axis of the lens unit,
The radius of the virtual sphere is determined from the center point by the first lens, the first holding unit that holds the first lens, the imaging unit, and the second holding that holds the imaging unit. The imaging apparatus according to claim 1, wherein the imaging device has a length up to a part of any of the sections.   The imaging device according to claim 2, wherein the center point is located on an optical axis of the first lens in a region between the first lens and the reflecting unit.   The first optical path length from the first lens to the imaging unit through the optical axis bent by the reflecting unit is assumed that the reflecting unit does not exist, and further, the virtual sphere 4 or 3, which is longer than a second optical path length from the first lens to the imaging unit when it is assumed that the imaging unit is disposed on the optical axis of the first lens. The imaging device described.   5. The center point according to claim 2, wherein the center point is an intersection of a rotation axis when the lens unit rotates in the pan direction and a rotation axis when the lens unit rotates in the tilt direction. Imaging device.   The lens unit includes a member that is movable along the optical axis after being bent at the reflecting portion or inserted into and removed from the optical axis after being bent at the reflecting portion. The imaging apparatus according to claim 2, further comprising:   The imaging device according to claim 6, wherein the member is a second lens or a filter.   8. The imaging according to claim 6, wherein the lens unit further includes a moving unit that moves the member inside the virtual sphere on the opposite side of the first lens with the reflecting unit interposed therebetween. apparatus.   The said lens unit further has a moving part which moves the said member to the area | region between the optical axis before being bent by the said reflection part, and the optical axis after being bent by the said reflection part. Imaging device.   10. The lens unit according to claim 2, further comprising a substrate on which a circuit is provided inside the virtual sphere on the side opposite to the first lens with the reflecting portion interposed therebetween. The imaging device described.   The imaging apparatus according to claim 1, further comprising a hemispherical cover that covers the lens unit.   The imaging device according to claim 1, wherein the driving unit rotates the lens unit in a pan direction and a tilt direction.

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