JP2021144139A - Imaging device, method of controlling the same, and optical device - Google Patents

Abstract

To provide an imaging device capable of adjusting an irradiation angle of illumination light to an optical system.SOLUTION: An imaging device 1 includes: an imaging element 31 for picking up imaging light incident on an imaging optical system from a subject; a light source 27 for emitting illumination light irradiated to the subject through the imaging optical system; an optical path separation element 25 that directs the illumination light to the imaging optical system and directs the imaging light from the imaging optical system to the imaging element by reflecting one of the imaging light and the illumination light and transmitting the other; and an illumination optical system that is arranged between the light source and the optical path separation element. The illumination optical system includes an illumination lens 21 movable in an optical axis direction of the illumination optical system.SELECTED DRAWING: Figure 3

Description

The present invention relates to an imaging device that illuminates a subject and captures images through a common optical system.

By performing the illumination and imaging of the subject through a common optical system (imaging optical system), it is possible to reduce the deviation from the illumination region with respect to the imaging region on the subject side.

Patent Document 1 discloses an optical inspection device that illuminates and images an object through a common optical system (objective lens). Further, Patent Document 2 discloses a microscope that illuminates and observes an object through a common optical system (objective lens). These optical inspection devices and microscopes have an optical separation element that directs the illumination light from the light source toward the objective lens and directs the object light from the objective lens toward the image pickup element or the observation optical system.

Japanese Unexamined Patent Publication No. 2007-024758 JP-A-2007-127816

However, in the configuration in which the illumination light is directed to the optical system via the light separation element, if the irradiation angle of the illumination light with respect to the optical system is not appropriate, the reflected light of the illumination light in the optical system and the member holding the optical system is unnecessary. It enters the image pickup element as light and generates ghosts and flares. Further, if a part of the illumination light is vignetted by the optical system or the like and does not reach the peripheral portion of the illumination region, the amount of peripheral light is reduced. Therefore, it is necessary to adjust the irradiation angle of the illumination light with respect to the optical system. In Patent Document 1 and Patent Document 2, it is not possible to adjust the irradiation angle of such illumination light.

The present invention provides an imaging device capable of adjusting the irradiation angle of illumination light with respect to an optical system.

The imaging device as one aspect of the present invention includes an imaging element that captures imaging light incident on the imaging optical system from the subject, a light source that emits illumination light that is emitted to the subject through the imaging optical system, and imaging light and illumination light. Between the light path separating element and the light source and the optical path separating element, the illumination light is directed to the imaging optical system and the imaging light from the imaging optical system is directed to the imaging element by reflecting one of them and transmitting the other. It has an arranged illumination optical system. The illumination optical system is characterized by including an illumination lens that can move in the optical axis direction of the illumination optical system. A camera system including the image pickup device and a rotation unit for rotating the image pickup device also constitutes another aspect of the present invention.

According to the present invention, it is possible to adjust the irradiation angle of the illumination light with respect to the imaging optical system by moving the illumination lens, and it is possible to suppress the generation of unnecessary light and the decrease in the amount of peripheral light of the illumination light.

An exploded perspective view of a surveillance camera including the imaging device of the first embodiment. The perspective view of the image pickup apparatus of Example 1. FIG. An exploded perspective view of the image pickup apparatus of the first embodiment. The block diagram which shows the structure of the image pickup apparatus of Example 1. FIG. The optical path diagram of the imaging light and the illumination light in Example 1. The flowchart which shows the lighting control processing in Example 1. FIG. The figure which shows the data table in Example 1. FIG. The flowchart which shows the lighting control processing in the modification 1. The figure which shows the data table in the modification 1. The perspective view of the image pickup apparatus of the modification 2. The flowchart which shows the lighting control processing in the modification 2. The figure which shows the data table in the modification 2. The block diagram which shows the structure of the image pickup apparatus of Example 2. FIG. The optical path diagram of the imaging light and the illumination light in Example 2. The perspective view of the image pickup apparatus of Example 3. FIG. An exploded perspective view of the imaging device of the third embodiment. The block diagram which shows the structure of the image pickup apparatus of Example 4. FIG.

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

FIG. 1 shows the configuration of a surveillance camera system including the image pickup apparatus 1 according to the first embodiment of the present invention. The image pickup apparatus 1 is held by a pan-tilt rotation unit 2 as a rotation unit. The pan-tilt rotation unit 2 changes the imaging direction of the imaging device 1 by rotating the imaging device 1 in the pan, tilt, and rotation directions. The image pickup device 1 is covered with a holding ring 4 and a dome cover 3 attached to the pan-tilt rotation unit 2 by a plurality of screws.

FIG. 2 shows the appearance of the image pickup device 1, and FIG. 3 shows the image pickup device 1 in an exploded manner. FIG. 4 shows the optical and electrical configurations of the imaging device 1. The image pickup device 1 is composed of an image pickup lens unit 10, a lighting unit 20, and an image pickup element unit 30, and can take an image of the subject while illuminating the subject.

The image pickup lens unit 10 has an image pickup optical system including a first lens group 110, a second lens group 120, a variable diaphragm 150, a third lens group 130, and a fourth lens group 140 in order from the subject side. The first lens group 110 is held by the first lens group frame 111, and the first lens group frame 111 is fixed to the front housing 170. The front housing 170 is fixed to the rear housing 180.

The second lens group 120 is held by the second lens group frame 121. The second lens group frame 121 is movably supported in the direction of the image pickup optical axis in which the optical axis (hereinafter, referred to as the image pickup optical axis) O of the image pickup optical system extends in engagement with the second group guide member 161. Further, the second lens group frame 121 is also engaged with the second group rotation limiting member 162, and the rotation around the second group guide member 161 is restricted. The second lens group frame 121 holds the second group rack 122. The second group rack 122 is engaged with the lead screw portion of the second group drive unit 123 including an actuator such as a stepping motor. When the lead screw portion is rotated by the second group drive unit 123, the second lens group frame 121 is driven together with the second group rack 122 in the imaging optical axis direction.

The third lens group 130 is held in the third lens group frame 131. The third lens group frame 131 engages with the 3-4 group guide member 163 and is supported so as to be movable in the image pickup optical axis direction. The third lens group frame 131 is also engaged with the 3-4 group rotation limiting member 164, and the rotation around the 3-4 group guide member 163 is restricted. The third lens group frame 131 holds the third group rack 132. The third group rack 132 is engaged with the lead screw portion of the third group drive unit 133 including an actuator such as a stepping motor, and when the lead screw portion is rotated by the third group drive unit 133, the third lens group frame 131 Is driven in the direction of the imaging optical axis together with the three-group rack 132.

By moving the second lens group 120 and the third lens group 130 in the imaging optical axis direction in a predetermined positional relationship, the magnification (zooming) of the imaging optical system is performed. Hereinafter, the positions of the second and third lens groups 120 and 130 are referred to as zoom positions.

The fourth lens group 140 is held in the fourth lens group frame 141. The fourth lens group frame 141 engages with the 3-4 group guide member 163 and is supported so as to be movable in the image pickup optical axis direction. The fourth lens group frame 141 is also engaged with the 3-4 group rotation restricting member 164, and the rotation around the 3-4 group guide member 163 is restricted. The fourth lens group frame 141 holds the fourth group rack 142. The 4th group rack 142 is engaged with the lead screw portion of the 4th group drive unit 143 such as a stepping motor, and when the lead screw portion is rotated by the 4th group drive unit 143, the 4th lens group frame 141 becomes the 4th group. It is driven in the direction of the imaging optical axis together with the rack 142.

Focusing of the imaging optical system is performed by moving the fourth lens group 140 in the direction of the imaging optical axis. Hereinafter, the position of the fourth lens group 140 is referred to as a focus position.

The variable diaphragm 150 is fixed to the rear housing 180. The variable aperture 150 is driven by an aperture drive unit 151 including an actuator such as a stepping motor to change the aperture diameter (aperture value), thereby adjusting the amount of light taken in from the subject.

The illumination unit 20 includes a light source unit (light source system) 27, an illumination optical system (21, 28), and an optical path separation element 25. The light source unit 27 uses an infrared LED as a light source and infrared light as unpolarized light (hereinafter referred to as illumination light) emitted from the infrared LED as linearly polarized light S-polarized light (first polarized light). It has a polarization conversion element that converts to. The polarization conversion element emits S-polarized light of unpolarized light as it is, and rotates the polarization direction of P-polarized light, which has a different polarization direction from S-polarized light, by a phase plate to emit it as S-polarized light. When a laser element capable of emitting S-polarized light is used as the light source, the polarization conversion element is unnecessary. The light source unit 27 is fixed to the lighting housing 200. The lighting housing 200 is fixed to the rear housing 180. The light emitting center of the light source unit 27 is arranged on the optical axis (hereinafter, referred to as the illumination optical axis) X of the illumination optical system.

The illumination optical system includes a second illumination lens group 28 and a first illumination lens group 21 arranged in order from the light source unit 27 side. The second illumination lens group 28 is held by the second illumination lens group frame 29, and the illumination second lens group frame 29 is fixed to the illumination housing 200.

The first illumination lens group 21 is held by the first illumination lens group frame 22. The first illumination lens group frame 22 is movably supported in the illumination optical axis direction in which the illumination optical axis X extends by engaging with the illumination lens guide member 201. Further, the first illumination lens group frame 22 is also engaged with the illumination lens rotation limiting member 202, and the rotation around the illumination lens guide member 201 is restricted. The first illumination lens group frame 22 holds the illumination lens rack 23. The illumination lens rack 23 is engaged with a lead screw portion of an illumination lens drive unit 24 including an actuator such as a stepping motor. When the lead screw portion is rotated by the illumination lens driving portion 24, the first illumination lens group frame 22 is driven together with the illumination lens rack 23 in the illumination optical axis direction. By moving the first illumination lens group 21 in the direction of the illumination optical axis, it is possible to adjust the luminous flux size and the irradiation angle of the illumination light emitted from the light source unit 27.

The optical path separation element 25 is a polarization beam splitter (PBS), and has a property of reflecting S-polarized light and transmitting P-polarized light (second polarized light) having a polarization direction different from that of the S-polarized light. The optical path separation element 25 reflects the illumination light as S-polarized light emitted from the illumination optical system and directs it toward the imaging optical system, and transmits P-polarized light among the imaging light incident on the imaging optical system from the imaging region including the subject. It is directed to the image pickup element 31 described later. The optical path separation element 25 is held by the PBS holding member 26, and the PBS holding member 26 is fixed to the rear housing 180. The illumination optical axis X is orthogonal to the imaging optical axis O and passes through the intersection of the optical path separation element 25 and the imaging optical axis O.

The image sensor unit 30 holds the image sensor 31. The image sensor 31 is held so that its center is located on the image pickup optical axis O. The image sensor unit 30 is fixed to the rear housing 180.

The image pickup element 31 is composed of a photoelectric conversion element such as a CCD sensor or a CMOS sensor, and captures an image pickup light (a subject image formed by) as P-polarized light transmitted through an optical path separation element 25. On the other hand, the illumination light as S-polarized light emitted from the imaging optical system toward the illumination region including the subject is diffusely reflected by the subject to become unpolarized light, and the P-polarized light of the unpolarized light is imaged as the imaging light. It reaches the element 31. Therefore, it is possible to simultaneously illuminate and image the subject.
Since the illumination light passes through the imaging optical system, which is an optical system in which the imaging light is common, there is little deviation (paralux) between the imaging region and the illumination region. That is, the position and size of the illumination area can be adjusted to the position and size of the imaging area.

The camera control unit 401 shown in FIG. 4 is a microcomputer including a CPU, an MPU, and the like, and communicates with a personal computer (PC) 402 as an external controller via a network (LAN, the Internet, etc.) (not shown). The camera control unit 401 controls the second group drive unit 123, the third group drive unit 133, the fourth group drive unit 143, and the aperture drive unit 151 in response to an instruction from the PC 402.

Further, the camera control unit 401 converts an image pickup signal as an analog signal read from the image pickup element 31 into a digital signal, and performs various image processing on the digital signal to generate image data. The image data is transmitted to the PC 402 via the network, and is displayed or recorded on the monitor in the PC 402.

Further, the camera control unit 401 also controls the light source unit 27 and the illumination lens drive unit 24. When the camera control unit 401 instructs the light source unit 27 to turn on, the light source in the light source unit 27 is turned on and the illumination light is emitted from the light source unit 27. The camera control unit 401 also controls the intensity (light intensity) of the illumination light from the light source unit 27. Further, the camera control unit 401 controls the position (movement) of the first illumination lens group 21 in the illumination optical axis direction via the illumination lens drive unit 24 so that the irradiation angle of the illumination light on the imaging optical system becomes appropriate. do. Hereinafter, the position control of the first illumination lens group 21 by the camera control unit 401 will be described.

When the illumination light is incident on the imaging optical system, the illumination light is reflected by the inner wall of the housing (front housing 170, etc.), the lens group frames 121, 131, 141, the variable diaphragm 150, etc. in the image pickup lens unit 10. The reflected light causes ghosts and flares as unnecessary light. Further, when a part of the illumination light is vignetting in the image pickup lens unit 10, the amount of illumination light reaching the peripheral portion of the illumination region is reduced and the amount of peripheral light is reduced.

FIG. 5 shows the optical paths of the imaging light and the illumination light in this embodiment. Here, the lens surface closest to the image pickup element (lens surface on the image pickup element side of the fourth lens group 140) in the image pickup optical system is set as the final lens surface, and as shown in part A in the drawing, the light path is emitted from the illumination optical system. Let Ns be the numerical aperture of the illumination light (dotted line) reflected by the separation element 25 as the numerical aperture on the final lens surface (or its vicinity). Further, the angle formed by the main ray (shown by a solid line in the figure) imaged at the maximum image height of the imaged light in the image sensor 31 (or its vicinity) and the imaged optical axis O is defined as θ. Further, the angle formed by the main light beam and the overline or underline (indicated by a broken line in the figure) in the image sensor 31 (or its vicinity) is defined as θδ. At this time, the numerical aperture Ns of illumination is
θ-θδ ≤ arcsin (Ns) ≤ θ + θδ (1)
The illumination lens driving unit 24 is controlled so that the first illumination lens group 21 moves to a position that satisfies the above conditions. More preferably
arcsin (Ns) = θ (2)
The position of the first illumination lens group 21 is controlled so as to be. As a result, it is possible to suppress the generation of unnecessary light and the decrease in the amount of peripheral light of the illumination light due to the illumination light being reflected or vignetting in the image pickup lens unit 10.

The flowchart of FIG. 6 shows an illumination control process (control method) executed by the camera control unit 401 to control the position of the first illumination lens group 21 in the illumination optical axis direction. The camera control unit 401 executes this process according to a computer program. FIG. 7 shows a data table that is held by the camera control unit 401 and shows the positions of the first illumination lens group 21 according to the zoom position and the focus position of the imaging optical system. In FIGS. 6 and 7, the first illumination lens group 21 is simply referred to as an “illumination lens”.

In step S501, the camera control unit 401 determines whether or not the zoom position or the focus position has been changed in response to an instruction from the PC 402. The camera control unit 401 changes the zoom position in response to a zooming instruction from the PC 402. Since the focus position (image plane) of the imaging optical system shifts when the zoom position is changed, the camera control unit 401 also changes the focus position to correct this. Further, the camera control unit 401 changes the focus position without changing the zoom position in response to the focusing instruction from the PC 402. If the zoom position or the focus position is changed, the process proceeds to step S502, and if not, the present process ends.

In step S502, the camera control unit 401 acquires the changed (current) zoom position and focus position. For example, the current zoom position is acquired by counting the number of pulses of the drive pulse signal applied to the second group drive unit 123 or the third group drive unit 133 from the initial zoom position. Similarly, the current focus position is acquired by counting the number of pulses of the drive pulse signal applied to the group 4 drive unit 143 from the initial focus position. However, it may be acquired by detecting the zoom position or the focus position using a position sensor (not shown).

Then, in step S503, the camera control unit 401 corresponds to the changed zoom position (0, 1, 2, ...) And the focus position (0, 1, 2, ...) From the table data shown in FIG. 7. 1 The position of the illumination lens group 21 (0, 1, 2, ..., 5, 6, ..., 10, 11, ...) is read out. When the zoom position or focus position is changed, the angle θ formed by the main ray forming the image at the maximum image height of the image pickup light and the image pickup optical axis O on the image pickup element 31 changes. Need to be adjusted. Therefore, the positions where the first illumination lens group 21 should be arranged for each zoom position and each focus position are calculated in advance so as to satisfy the equation (1) and stored in the camera control unit 401 as a data table.

Next, in step S504, the camera control unit 401 controls the illumination lens driving unit 24 so that the first illumination lens group 21 moves to the position read out in step S503. At this time, the camera control unit 401 counts the number of pulses of the drive pulse signal applied to the illumination lens drive unit 24 from the initial lens position to obtain the current position and step of the first illumination lens group 21. The difference from the position read out in S503 is calculated, and a drive pulse signal having a number of pulses corresponding to the difference is applied to the illumination lens drive unit 24. Then, this process is terminated.

According to this embodiment, even when the zoom position and the focus position of the image pickup lens unit 10 are changed, it is possible to suppress the incident of unnecessary light on the image sensor 31 and the decrease in the amount of peripheral light of the illumination light.
(Modification example 1)
The flowchart of FIG. 8 shows the illumination control process executed by the camera control unit 401 in order to control the position of the first illumination lens group 21 in the illumination optical axis direction in the first modification of the first embodiment. FIG. 9 shows a data table showing the position of the first illumination lens group 21 according to the aperture value (F value) of the imaging optical system, the zoom position, and the focus position held by the camera control unit 401 in this modified example. There is. In FIGS. 8 and 9, the first illumination lens group 21 is simply referred to as an “illumination lens”.

In step S511, the camera control unit 401 determines whether or not the zoom position, focus position, or aperture value has been changed in response to an instruction from the PC 402. The camera control unit 401 controls the aperture drive unit 151 so that the variable aperture 150 becomes the commanded aperture value in response to a command of the aperture value from the PC 402. If the zoom position, focus position or aperture value is changed, the process proceeds to step S512, and if not, this process ends.

In step S512, the camera control unit 401 acquires the changed (current) zoom position, focus position, and aperture value. For example, the current aperture value is acquired by counting the number of pulses of the drive pulse signal applied to the aperture drive unit 151 from the initial aperture value.
Then, in step S513, the camera control unit 401 uses the table data shown in FIG. 9 to obtain the changed aperture value (1.4, 2.0, ...), Zoom position (0, 1, ...), And focus position (0, 1, ...). The positions (0, 1, 2, 3, ..., 5, 6, ..., 7, 8, ...) of the first illumination lens group 21 corresponding to 0, 1, 2, ...) Are read out. When the image pickup lens unit 10 has vignetting, when the aperture value changes, the angle θ formed by the main ray imaged at the maximum image height of the image pickup light and the image pickup optical axis О on the image pickup element 31 changes, so that the focus changes. In addition to changing the position and zoom position, it is necessary to adjust the numerical aperture Ns described above even when the aperture value is changed. Therefore, the position where the first illumination lens group 21 should be arranged for each aperture value, each zoom position, and each focus position is calculated in advance so as to satisfy the equation (1) and stored in the camera control unit 401 as a data table. back.

Next, in step S514, the camera control unit 401 controls the illumination lens driving unit 24 so that the first illumination lens group 21 moves to the position read out in step S513. Then, this process is terminated.

According to this embodiment, even when the zoom position, focus position, and aperture value of the image pickup lens unit 10 are changed, it is possible to suppress the incident of unnecessary light on the image sensor 31 and the decrease in the amount of peripheral light of the illumination light.
(Modification 2)
FIG. 10 shows the appearance of the image pickup apparatus 1a as a modification 2 which is a modification of the modification 1. In this embodiment, the image pickup lens unit 10a is an interchangeable lens unit that can be attached to and detached from the image pickup apparatus main body (rear housing 180). Various types of image pickup lens units 10a are mechanically and electrically connected to a mount portion M provided in the image pickup apparatus main body by bayonet coupling or the like.

The flowchart of FIG. 11 shows the illumination control process executed by the camera control unit 401 in order to control the position of the first illumination lens group 21 in the illumination optical axis direction in this modification. FIG. 12 shows the model of the image pickup lens unit 10a, the aperture value (F value) of the image pickup optical system, the position of the first illumination lens group 21 according to the zoom position and the focus position, held by the camera control unit 401 in this modified example. The data table showing is shown. In FIGS. 11 and 12, the first illumination lens group 21 is simply referred to as an “illumination lens”.

In step S521, the camera control unit 401 determines whether or not the image pickup lens unit 10a is attached to the image pickup apparatus main body. If the image pickup lens unit 10a is attached, the process proceeds to step S522, and if the image pickup lens unit 10a is not attached, this process ends.

In step S522, the camera control unit 401 acquires the model (which may be an identification number or a serial number), the zoom position, the focus position, and the aperture value of the mounted image pickup lens unit 10a.

Then, in step S513, the camera control unit 401 obtains the model (A, B, ...) And the aperture value (1.4, 2.0, ...) Of the attached image pickup lens unit 10a from the table data shown in FIG. Positions (0,1,2,3, ..., 5,6, ..., 7) of the first illumination lens group 21 corresponding to the zoom position (0,1, ...) and the focus position (0,1,2, ...) , 8, ..., 13, 14, ..., 17, 18, ...) are read out. The image pickup optical system provided in the mounted image pickup lens unit 10a changes the angle θ formed by the main ray forming an image at the maximum image height of the image pickup light and the image pickup optical axis О on the image pickup element 31, as described above. It is necessary to adjust the numerical aperture Ns. Therefore, for each model of the image pickup lens unit 10a, the position where the first illumination lens group 21 should be arranged for each aperture value, each zoom position, and each focus position is calculated in advance so as to satisfy the equation (1) in the data table. Is stored in the camera control unit 401.

Next, in step S524, the camera control unit 401 controls the illumination lens driving unit 24 so that the first illumination lens group 21 moves to the position read out in step S523. Then, this process is terminated.

According to this embodiment, even when image pickup lens units 10a having different imaging optical systems are attached, unnecessary light is incident on the image pickup element 31 and illuminated regardless of its zoom position, focus position, and aperture value. It is possible to suppress the peripheral light falloff of light.

If the number of illumination apertures Ns satisfies the above-mentioned equation (1) despite the change of any of the zoom position, the focus position, the aperture value, and the model, the camera control unit 401 is the first illumination lens group. Control may be performed so that the 21 is not moved.

Further, in this embodiment, the case where the position of the first illumination lens group 21 with respect to the zoom position, the focus position, the aperture value and the model is read out from the data table stored in advance has been described, but every time they are changed, the first The position of the illumination lens group 21 may be calculated using an arithmetic formula.

FIG. 13 shows the optical and electrical configurations of the image pickup apparatus 1b according to the second embodiment of the present invention. In this embodiment, the components common to those in the first embodiment (FIG. 3) are designated by the same reference numerals as those in the first embodiment. The image pickup apparatus 1b of the present embodiment has a configuration in which the positions of the lighting unit 20 and the image pickup element 31 are interchanged with respect to the first embodiment. Other configurations are the same as in the first embodiment.

In the lighting unit 20, the light source unit 27b converts the infrared LED and the infrared light (illumination light) as unpolarized light emitted from the infrared LED into P-polarized light (first polarized light) as linearly polarized light. It has a polarization conversion element to convert. The polarization conversion element emits P-polarized light of unpolarized light as it is, rotates the polarization direction of S-polarized light by a phase plate, and emits it as P-polarized light. When a laser element capable of emitting P-polarized light is used as the light source, the polarization conversion element is unnecessary.

The optical path separation element 25 is a polarization beam splitter having a characteristic of reflecting S-polarized light (second polarized light) and transmitting P-polarized light, as in the first embodiment. The optical path separation element 25 transmits the illumination light as P-polarized light emitted from the illumination optical system and directs it toward the imaging optical system, and transmits S-polarized light among the imaging light incident on the imaging optical system from the imaging region including the subject. Let it go to the image pickup element 31.

The imaging optical axis O2 from the optical path branching element 25 to the imaging element 31 is orthogonal to the illumination optical axis X and passes through the intersection of the optical path separating element 25 and the imaging optical axis O. The illumination optical axis X is coaxial with the imaging optical axis O. The image sensor 31 is held so that its center is located on the image pickup optical axis O2.

The image pickup device 31 takes an image of the image pickup light (the subject image formed by) as P-polarized light transmitted through the optical path separation element 25. On the other hand, the illumination light as P-polarized light emitted from the imaging optical system toward the illumination region including the subject is diffusely reflected by the subject to become unpolarized light, and the S-polarized light of the unpolarized light is imaged as the imaging light. It reaches the element 31. Therefore, it is possible to simultaneously illuminate and image the subject.

In this embodiment as well, as in the first embodiment, since the illumination light and the imaging light pass through the imaging optical system which is a common optical system, there is little paralux between the imaging region and the illumination region.

Further, also in this embodiment, as in the first embodiment, when the illumination light is incident on the imaging optical system, the illumination light is reflected by the inner wall of the housing in the imaging lens unit 10, the lens group frame, the variable aperture 150, and the like. , The reflected light generates ghosts and flares as unnecessary light. Further, when a part of the illumination light is vignetting in the image pickup lens unit 10, the amount of illumination light reaching the peripheral portion of the illumination region is reduced and the amount of peripheral light is reduced.

FIG. 14 shows the optical paths of the imaging light and the illumination light in this embodiment. Here, as shown in part C in the drawing, the numerical aperture of the illumination light (dotted line) emitted from the illumination optical system and transmitted through the optical path separation element 25 on the final lens surface (or its vicinity) of the imaging optical system is used. Let the numerical aperture of illumination be Ns. Further, the angle formed by the main ray (shown by a solid line in the figure) imaged at the maximum image height of the imaged light in the image sensor 31 (or its vicinity) and the imaged optical axis O2 is defined as θ. Further, the angle formed by the main light beam and the overline or underline (indicated by a broken line in the figure) in the image sensor 31 (or its vicinity) is defined as θδ. At this time, the numerical aperture Ns of illumination is
θ-θδ ≤ arcsin (Ns) ≤ θ + θδ
The illumination lens driving unit 24 is controlled so that the first illumination lens group 21 moves to a position that satisfies the above conditions. More preferably
arcsin (Ns) = θ (2)
The position of the first illumination lens group 21 is controlled so as to be. As a result, it is possible to suppress the generation of unnecessary light and the decrease in the amount of peripheral light of the illumination light due to the illumination light being reflected or vignetting in the image pickup lens unit 10. The illumination control process for controlling the position of the first illumination lens group 21 is the same as in the first embodiment.

FIG. 15 shows the appearance of the image pickup apparatus 1c according to the third embodiment of the present invention, and FIG. 16 shows the image pickup apparatus 1c in an exploded manner. In this embodiment, the components common to those of the first embodiment (FIGS. 2 and 3) are designated by the same reference numerals as those of the first embodiment. In the image pickup apparatus 1c of the present embodiment, the illumination unit 20c is configured so that the installer can manually adjust the position of the first illumination lens group 21 when the surveillance camera system is installed.

In the illumination unit 20c, the second illumination lens group frame 29 holding the second illumination lens group 28 is fixed to the illumination fixing cylinder 203. The lighting fixing cylinder 203 is fixed to the rear housing 180. The illumination rotary cylinder 204 is engaged with the illumination fixed cylinder 203 and the second illumination lens group frame 29, and is rotatably held around the illumination optical axis X.

The first illumination lens group frame 22 holding the first illumination lens group 21 has an engagement pin portion 22a, and the engagement pin portion 22a engages with a linear guide groove portion 203a formed in the illumination fixing cylinder 203. There is. As a result, the first illumination lens group frame 22 is supported so as to be movable in the illumination optical axis direction. Further, the engaging pin portion 22a is also engaged with the cam groove portion 204a formed in the illumination rotating cylinder 204. Therefore, when the illumination rotating cylinder 204 is manually rotated around the illumination optical axis X, the engaging pin portion 22a guided in the illumination optical axis direction by the linear guide portion 203a moves from the cam groove portion 204a in the illumination optical axis direction. Receives driving force. As a result, the first illumination lens group frame 22 (that is, the first illumination lens group 21) moves in the illumination optical axis direction.

A method of adjusting the position of the first illumination lens group 21 will be described. First, adjustment imaging is performed to adjust the position of the first illumination lens group 21. Specifically, the image pickup lens unit 10 is set to the zoom position, the focus position, and the aperture value when the illumination light is used. After that, the light source unit 27 is turned on, the image data acquired by the image sensor 31 is transmitted to the PC 402, and the captured image is displayed on the monitor. The gain, shutter speed, and white balance of the image sensor 31 at the time of adjusted imaging are kept constant. At the time of adjusted imaging, it is preferable to attach a lens cap to the image pickup lens unit 10 or to make a plane parallel to the image pickup surface of the image sensor 31 a subject image.

Next, the first illumination lens group 21 is moved in the direction of the illumination optical axis by manually rotating the illumination rotary cylinder 204 while checking the displayed captured image. At this time, by moving the first illumination lens group 21 to a position where the numerical aperture Ns described in the first embodiment satisfies the equation (1), the illuminance unevenness due to ghosts and flares and the peripheral light falloff are reduced. Is obtained.

In this embodiment, the image pickup lens unit 10 may be an interchangeable lens unit as in the modification 2 of the first embodiment, and the arrangements of the illumination unit 20c and the image pickup element unit 30 are exchanged as in the second embodiment. May be good.

FIG. 17 shows the optical and electrical configurations of the image pickup apparatus 1d according to the fourth embodiment of the present invention. In this embodiment, the components common to those in the first embodiment (FIG. 3) are designated by the same reference numerals as those in the first embodiment.

When the image pickup device 1d is an interchangeable lens type, an image pickup lens unit 10d as an interchangeable lens unit having different maximum image heights may be mounted. In order to suppress unnecessary light such as ghosts and peripheral illumination drop regardless of the maximum image height of the mounted image pickup lens unit 10d, the first illumination lens group 21 is moved near the final lens surface of the image pickup lens unit 10. It is necessary not only to adjust the numerical aperture Ns of the illumination, but also to adjust the irradiation range of the illumination light incident on the optical path separation element 25.

Therefore, in this embodiment, the illumination unit 20d is configured so that not only the first illumination lens group 21 but also the light source unit 27 and the second illumination lens group 28 can be moved in the direction of the illumination optical axis. .. Other configurations are the same as in the first embodiment.

To adjust the irradiation range of the illumination light on the optical path separation element 25, the camera control unit 401 controls the light source drive unit 205 including an actuator such as a stepping motor while the position of the first illumination lens group 21 is fixed. This is performed by integrally moving the light source unit 27 and the second illumination lens group 28 in the illumination optical axis direction. As a result, even if the first illumination lens group 21 is moved in the direction of the illumination optical axis, the numerical aperture of the illumination light incident on the first illumination lens group 21 can be maintained. In this way, it is possible to adjust the numerical aperture Ns and the irradiation range of the illumination light on the optical path separation element 25.

In this embodiment, the arrangement of the lighting unit 20c and the image sensor unit 30 may be interchanged as in the second embodiment.

In Examples 1 to 4, zooming and focusing may be performed manually. In this case, the zoom position and the focus position may be detected and acquired by using a position sensor.

Further, in Examples 1 to 4, the illumination optical system may include a variable diaphragm. In this case, the variable diaphragm is preferably arranged between the first illumination lens group 21 and the optical path separation element 25 or between the first illumination lens group 21 and the second illumination lens group 28. By using the variable diaphragm as a mask, it is possible to reduce unnecessary illumination light emitted outside the optical path of the adjusted illumination optical system.

Further, in Examples 1 to 4, the imaging lens unit 10 (10a, 10d) may be a single focus lens. Further, in Examples 1 to 4, the light source in the light source unit 27 may be a visible light light source such as a white light source or a monochromatic light source.

Further, in Examples 1 to 4, the optical path separation element 25 may be an unpolarized beam splitter. In that case, the polarization conversion element of the light source unit 27 is unnecessary.
(Other Examples)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Each of the above-described examples is only a representative example, and various modifications and changes can be made to each of the examples in carrying out the present invention.

1 Imaging device 10 Imaging lens unit 20 Lighting unit 21 First illumination lens group 25 Optical path separation element 27 Light source unit 31 Imaging element

Claims (11)

An image sensor that captures the imaging light incident on the imaging optical system from the subject,
A light source that emits illumination light that illuminates the subject through the imaging optical system,
By reflecting one of the imaging light and the illumination light and transmitting the other, the illumination light is directed to the imaging optical system, and the imaging light from the imaging optical system is directed to the imaging element. Separation element and
It has an illumination optical system arranged between the light source and the optical path separation element.
The illumination optical system is an imaging device including an illumination lens that can move in the optical axis direction of the illumination optical system. An actuator that moves the illumination lens in the direction of the optical axis,
The imaging device according to claim 1, further comprising a control means for controlling the actuator. The imaging optical system is capable of zooming and can be zoomed.
The imaging device according to claim 2, wherein the control means controls the actuator so as to change the position of the illumination lens according to the zooming. The imaging optical system is capable of focusing and
The imaging device according to claim 2, wherein the control means controls the actuator so as to change the position of the illumination lens according to the focusing. The imaging optical system includes a variable diaphragm.
The imaging device according to claim 2, wherein the control means controls the actuator so as to change the position of the illumination lens in response to a change in the aperture value of the variable aperture. The imaging optical system can be attached to and detached from the imaging device.
The imaging device according to claim 2, wherein the control means controls the actuator so as to change the position of the illumination lens according to the imaging optical system mounted on the imaging device. The control means uses the lens surface closest to the image pickup element in the image pickup optical system as the final lens surface, and the illumination light emitted from the illumination optical system and reflected or transmitted by the optical path separation element on the final lens surface. The numerical aperture is the numerical aperture of illumination Ns, the angle formed by the main ray forming the maximum image height of the imaging light in the imaging element and the optical axis of the imaging optical system is θ, and the main ray in the imaging element. When the angle between the upper line and the lower line is θδ, the numerical aperture Ns of illumination is
θ-θδ ≤ arcsin (Ns) ≤ θ + θδ
The imaging apparatus according to any one of claims 2 to 6, wherein the actuator is controlled so as to move the illumination lens to a position satisfying the above condition. The imaging device according to any one of claims 1 to 7, wherein the light source is configured to be movable in the optical axis direction of the illumination optical system separately from the illumination lens. The imaging device according to any one of claims 1 to 8, wherein the illumination optical system includes a variable diaphragm. It has a light source system that includes the light source and emits a first polarized light that becomes the illumination light.
The optical path separation element is a polarization separation element that reflects one of the first polarized light and the second polarized light as the imaging light whose polarization direction is different from that of the first polarized light and transmits the other. The imaging apparatus according to any one of claims 1 to 9, wherein the image pickup apparatus is provided. The imaging device according to any one of claims 1 to 10.
A camera system including a rotating unit for rotating the image pickup device.

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