JP2010231051A - Filter holding mechanism, lens apparatus, and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform imaging in a wavelength area ranging from visible light to near-infrared light and to reduce blur due to chromatic aberration. <P>SOLUTION: A selector 130 making a selection between an IR cut filter 131 and a first optical filter 132, which intercepts light with wavelength in a specific range from visible light to the far-red light, on an optical path 111 is disposed on the object side of a lens apparatus 110, in an optical system of the lens apparatus 110, or behind the optical system of the lens apparatus 110. Therefore, external light transmitting through the lens apparatus 110 is received by an imaging element 121 through the IR cut filter 131 or the first optical filter 132 held on the optical path 111. Consequently, external light with wavelength partially intercepted by the IR cut filter 131 or the first optical filter 132 is incident on the imaging element 121. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a filter holding mechanism, a lens device, and an imaging device that include an optical filter that adjusts optical performance.

  In recent years, imaging devices such as digital cameras have been required to have higher magnification as well as further miniaturization. In order to meet this demand, there is a demand for a lens device that can be mounted on an image pickup apparatus and that is capable of high magnification. An imaging photoelectric conversion element, that is, an imaging element is arranged in the imaging apparatus main body. The image sensor receives external light incident through the lens device, performs photoelectric conversion, and outputs an electrical signal corresponding to the amount of incident light.

  Specifically, the imaging device is realized by a solid-state imaging device such as a CCD image sensor (Charge Coupled Device Image Sensor) or a CMOS (Complementary Metal Oxide Semiconductor) image sensor. Since these imaging elements receive a wide range of wavelengths from ultraviolet light to visible light including near infrared light, chromatic aberration occurs.

  Here, the wavelength range of visible light is defined as 400 nm or more and less than 700 nm, for example. The reason is that in a photographic lens, the wavelength range of visible light is generally set to, for example, not less than 360 nm and less than 700 nm because of the sensitivity of the human eye, but in an electronic recording medium such as a CCD image sensor, the wavelength is 360 nm. This is because the sensitivity of light of less than 400 nm is low. Moreover, the wavelength range of near infrared light is defined as 700 nm or more and less than 1100 nm, for example. This is because the upper limit of sensitivity of a CCD image sensor, a CMOS image sensor, or the like can pick up an image up to light having a wavelength of 1100 nm. The wavelength range of visible light or near-infrared light is not limited to this, and can be variously changed depending on the type of lens and the purpose of use.

  FIG. 12 is an explanatory diagram showing correction of chromatic aberration of visible light. FIG. 13 is an explanatory diagram showing chromatic aberration from visible light to near infrared light. As shown in FIG. 12, even if the chromatic aberration of visible light (for example, light having a wavelength of 400 nm or more and less than 700 nm) is corrected, as shown in FIG. 13, near infrared light (for example, having a wavelength of 700 nm or more and less than 1100 nm). Even light (chromatic) chromatic aberration cannot be corrected.

  In order to solve such problems, the visible light region cut filter and the near infrared light region cut filter (IR cut filter) are taken in and out of the optical path of the lens system to capture only visible light or near infrared light. An apparatus and a lens apparatus have been proposed (for example, see Patent Document 1 below).

  FIG. 14 is an explanatory diagram showing correction of chromatic aberration when an IR cut filter is inserted. The IR cut filter transmits visible light and absorbs near infrared light. Therefore, as shown in FIG. 14, for a bright subject, an IR cut filter is inserted into the optical path of the lens to receive only visible light, so the wavelength range received by the image sensor is narrowed and the size is reduced. It is possible to correct chromatic aberration while maintaining the above.

  FIG. 15 is an explanatory diagram showing chromatic aberration when near-infrared light is projected by a near-infrared projector. The visible light region cut filter transmits infrared light and absorbs visible light. Therefore, as shown in FIG. 15, when the IR cut filter is removed and the visible light cut filter is inserted, the near infrared light is projected onto the subject to shoot, so the focus position of the visible light and the near infrared light Even if the focus position is slightly deviated, it is possible to refocus the projected light image. Therefore, if the chromatic aberration of visible light is corrected as shown in FIG. 12, even if the chromatic aberration up to near infrared light is not corrected as shown in FIG. 13, as shown in FIG. When projecting near-infrared light with a light projector, no major problem occurred in resolution.

JP 2008-152032 A

  However, in a camera used for monitoring that images a bright subject and a dark subject with a single imaging device depending on the time zone, light from visible light to near infrared light is captured as much as possible. There is a need to eliminate blind spots. For this reason, in the method of switching between the visible light cut filter and the IR cut filter as in Patent Document 1 described above, the subject is photographed when there is no visible light even when there is near infrared light when switched to the IR cut filter. On the other hand, when switching to the visible light cut filter, there is a problem that even if there is visible light, the subject cannot be photographed without near infrared light.

  In order to solve such problems, in recent years, the IR cut filter has been removed for the purpose of increasing the amount of light incident on the image sensor without projecting on a dark subject, and the visible light has not been inserted. There are many cases of photographing up to infrared light. For this reason, the resolution of a subject illuminated with any light from visible light to near-infrared light is reduced by chromatic aberration without inserting a visible light cut filter or an IR cut filter into the optical path of the lens system. There is a demand for imaging without any problems.

  However, since an image of mixed light from visible light to near-infrared light is formed, even if the chromatic aberration of visible light is corrected as shown in FIG. 12, visible light as shown in FIG. If the chromatic aberration from to near infrared light is not corrected, the image will be greatly blurred. For this reason, it is conceivable to use a lens formed of a glass having a small dispersion. However, since a glass having a small dispersion is expensive, there is a problem that the cost is increased. Further, since the glass with small dispersion has a low refractive index, there is a problem that aberration occurs because the curvature of the lens becomes strong, and the lens becomes large in order to correct this aberration.

  In particular, in the case of a high-magnification lens device, visible light to near-infrared light is difficult even though it is difficult to correct chromatic aberration in the entire zoom range from the wide end to the tele end only in the visible light range. It is difficult to correct the chromatic aberration up to the above while keeping downsizing. As described above, it is difficult to achieve both downsizing, high performance, and low cost in a camera used for monitoring purposes in which a single imaging device captures a bright subject and a dark subject depending on the time of day. There is a problem.

  In order to eliminate the above-described problems caused by the prior art, the present invention can capture a wavelength range from visible light to near infrared light, and can reduce blur caused by chromatic aberration and a lens device. It is another object of the present invention to provide an imaging device.

  In order to solve the above-described problems and achieve the object, the filter holding mechanism according to the invention of claim 1 blocks some wavelengths in the wavelength range from visible light to near-infrared light, and visible light. A first optical filter that transmits at least a part of the wavelength and at least a part of the near-infrared light, and a holding unit that holds the first optical filter on the optical path. To do.

  According to the first aspect of the present invention, since only a part of the wavelength range from visible light to near infrared light is blocked, an image is picked up regardless of whether light of visible light or near infrared light is incident. Since the usable wavelength range is narrower than the entire wavelength range from visible light to near infrared light, blur due to chromatic aberration can be suppressed.

  A filter holding mechanism according to a second aspect of the present invention is the filter holding mechanism according to the first aspect, further comprising a switching unit that switches between the first optical filter and a second optical filter that blocks near-infrared light. It is further provided with a feature.

  According to the second aspect of the present invention, when shooting a bright subject, a clear color image can be captured by using an IR cut filter that blocks near-infrared light. Furthermore, when photographing a dark subject, it is possible to capture images in both the visible light region and the near infrared region.

  According to a third aspect of the present invention, there is provided the filter holding mechanism according to the first or second aspect, wherein the first optical filter blocks a part of wavelengths on the short wavelength side of visible light. And

  According to the third aspect of the present invention, since the usable wavelength range can be narrowed to a part of the long wavelength side of visible light and near infrared light, blur due to chromatic aberration can be reduced.

  According to a fourth aspect of the present invention, there is provided the filter holding mechanism according to the first or second aspect, wherein the first optical filter blocks some wavelengths on the long wavelength side of near infrared light. It is characterized by.

  According to the fourth aspect of the present invention, since the usable wavelength range can be narrowed to a part of the short wavelength side of visible light and near infrared light, blur due to chromatic aberration can be reduced.

  According to a fifth aspect of the present invention, there is provided the filter holding mechanism according to the first or second aspect of the present invention, wherein the first optical filter has a wavelength of a short wavelength side of visible light and near infrared light. It is characterized by blocking some wavelengths on the long wavelength side.

  According to the fifth aspect of the present invention, the usable wavelength range can be narrowed to a part on the long wavelength side of the visible light and a part on the short wavelength side of the near-infrared light, so that the blur due to chromatic aberration is further reduced. Can do.

  The filter holding mechanism according to a sixth aspect of the present invention is the filter holding mechanism according to the second aspect, wherein the switching unit blocks a part of wavelengths on the short wavelength side of visible light as the first optical filter. An optical filter, an optical filter that blocks some wavelengths on the long wavelength side of near infrared light, or a part of wavelengths on the short wavelength side of visible light and a part of wavelengths on the long wavelength side of near infrared light Any one of the optical filters and the second optical filter are switched.

  According to the sixth aspect of the present invention, even when using a lens apparatus having different chromatic aberration or purpose of use, it is possible to take an image regardless of whether visible light or near-infrared light is incident, and blur due to chromatic aberration is eliminated. Can be reduced.

  A lens device according to a seventh aspect of the present invention includes the filter holding mechanism having an optical filter according to any one of the first to sixth aspects, and a plurality of lenses that allow external light to enter the optical filter. The holding mechanism is arranged on any one of the object side of the lens, between the lenses, or on the rear side of the lens.

  According to the seventh aspect of the present invention, since only a part of the wavelength range from visible light to near-infrared light is cut off, imaging is performed regardless of whether visible light or near-infrared light is incident. Since the usable wavelength range is narrower than the entire wavelength range from visible light to near infrared light, blur due to chromatic aberration can be suppressed. Furthermore, it can be easily applied to a small lens device having high optical performance and capable of optical zooming at a low manufacturing cost.

  According to an eighth aspect of the present invention, there is provided an imaging apparatus according to any one of the first to sixth aspects, wherein the filter holding mechanism having an optical filter, a photoelectric conversion element for imaging, and external light is passed through the optical filter. And a lens device having a plurality of lenses to be incident on the conversion element.

  According to the eighth aspect of the present invention, since only a part of the wavelength range from visible light to near infrared light is cut off, imaging is performed regardless of whether visible light or near infrared light is incident. Since the usable wavelength range is narrower than the entire wavelength range from visible light to near infrared light, blur due to chromatic aberration can be suppressed. Furthermore, it can be easily applied to an image pickup apparatus having a small lens device having high optical performance and capable of optical zooming at a low manufacturing cost.

  According to the filter holding mechanism, the lens device, and the imaging device according to the present invention, it is possible to take an image of a wavelength range from visible light to near infrared light, and to reduce blur due to chromatic aberration. Furthermore, the present invention has an effect that it can be easily applied to a small lens device having high optical performance and capable of optical zooming at a low manufacturing cost.

1 is an explanatory diagram illustrating a configuration of an imaging apparatus according to a first embodiment. 1 is an explanatory diagram illustrating a configuration of an imaging apparatus according to a first embodiment. 1 is an explanatory diagram illustrating a configuration of an imaging apparatus according to a first embodiment. FIG. 3 is an explanatory diagram illustrating another configuration of the imaging apparatus according to the first embodiment. FIG. 6 is a characteristic diagram illustrating characteristics of the first optical filter according to the first embodiment. FIG. 6 is an explanatory diagram showing an axial spot image on the image plane of external light that has passed through the first optical filter according to the first embodiment. FIG. 10 is a characteristic diagram illustrating characteristics of the first optical filter according to the second embodiment. FIG. 10 is an explanatory diagram showing an axial spot image on the image plane of external light that has passed through the first optical filter according to the second embodiment. FIG. 10 is a characteristic diagram illustrating characteristics of the first optical filter according to the third embodiment. FIG. 10 is a characteristic diagram illustrating optimum characteristics of the first optical filter according to the third embodiment. FIG. 10 is an explanatory diagram showing an axial spot image on the image plane of external light transmitted through the first optical filter according to the third embodiment. It is explanatory drawing shown about correction | amendment of the chromatic aberration of visible light. It is explanatory drawing shown about chromatic aberration from visible light to near-infrared light. It is explanatory drawing shown about correction | amendment of chromatic aberration at the time of inserting an IR cut filter. It is explanatory drawing shown about a chromatic aberration at the time of projecting near-infrared light with a near-infrared projector.

  Exemplary embodiments of a filter holding mechanism, a lens device, and an imaging device according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment 1)
(About the configuration of the imaging device)
First, the configuration of the imaging apparatus according to the first embodiment of the present invention will be described. 1 to 3 are explanatory diagrams illustrating the configuration of the imaging apparatus according to the first embodiment. As illustrated in FIGS. 1 to 3, the imaging device 100 includes a lens device 110 and an imaging device main body 120. The imaging device main body 120 includes an imaging device 121 such as a CCD image sensor or a CMOS image sensor, and external light is incident on the lens device 110.

  The lens device 110 also includes a switching device 130 that switches between the first optical filter 132 and the second optical filter 131. The switching device 130 holds either the first optical filter 132 or the second optical filter 131 on the optical path 111. The second optical filter 131 is an IR cut filter or the like that transmits visible light and blocks near infrared light (hereinafter, the second optical filter is referred to as an IR cut filter). Specifically, for example, the IR cut filter 131 blocks light having a wavelength of 700 nm or more. The first optical filter 132 blocks a part of wavelengths in the wavelength range from visible light to near-infrared light (for example, wavelengths from 400 nm to 1100 nm) and is visible, as will be described in detail later. Transmit at least some wavelengths of light as well as at least some wavelengths of near infrared light. The switching device 130 may be disposed on the object side of the lens device 110 (FIG. 1), may be disposed in the optical system of the lens device 110 (FIG. 2), or may be disposed in the optical system of the lens device 110. You may arrange | position behind (FIG. 3).

  Thus, the external light transmitted through the lens device 110 is received by the image sensor 121 via the IR cut filter 131 or the first optical filter 132 held on the optical path 111. For this reason, in the image sensor 121, external light having some wavelengths blocked by the IR cut filter 131 or the first optical filter 132 is incident.

(Other configurations of the imaging device)
Next, another configuration of the imaging apparatus according to the first embodiment will be described. FIG. 4 is an explanatory diagram of another configuration of the imaging apparatus according to the first embodiment. As shown in FIG. 4, the switching device 130 may be arranged in the imaging device main body 120 as long as it is on the optical path 111 and before the imaging device 121.

(About the characteristics of the first optical filter)
Next, characteristics of the first optical filter 132 according to the first embodiment will be described. FIG. 5 is a characteristic diagram illustrating characteristics of the first optical filter according to the first embodiment. In FIG. 5, the vertical axis represents the transmittance, and the horizontal axis represents the wavelength. As shown in FIG. 5, the first optical filter 132 blocks light on the short wavelength side of visible light. Specifically, the first optical filter 132 blocks light having a wavelength less than an arbitrary wavelength among light having a wavelength of 450 nm to 650 nm, for example.

  The reason for this is that when the visible light wavelength range is 400 nm or more and less than 700 nm, for lenses with relatively small chromatic aberration, light with a wavelength of 450 nm or less is blocked to prevent image degradation. Because you can. In addition, in a lens having a relatively large amount of chromatic aberration, imaging is performed with a mixture of visible light and near-infrared light by blocking the shortest wavelength at which visible light can be imaged, for example, light having a wavelength of 650 nm or less. This is because image degradation can be reduced. Furthermore, blocking light having a wavelength greater than 650 nm is almost the same as blocking all of the visible light range, so that imaging cannot be performed even when visible light is incident.

  FIG. 6 is an explanatory diagram showing an axial spot image on the image plane of external light that has passed through the first optical filter according to the first embodiment. In FIG. 6, the case where the 1st optical filter 132 which interrupts | blocks the light whose wavelength is less than 550 nm is inserted is demonstrated. FIG. 6 shows the shortest wavelength (for example, 550 nm) on the short wavelength side of visible light out of the light transmitted through the first optical filter 132 and incident on the image plane, the boundary between visible light and near infrared light. An on-axis spot image of light having a wavelength (for example, 700 nm) and the longest wavelength (for example, 1100 nm) on the long wavelength side of near infrared light is shown. As shown in FIG. 6, among the light incident on the image plane in FIG. 13, the shortest wavelength (for example, 400 nm) on the short wavelength side of visible light, the wavelength at the boundary between visible light and near-infrared light (for example, 700 nm), it can be seen that the range of each spot image is narrower than the range of the on-axis spot image of the light having the longest wavelength (for example, 1100 nm) on the long wavelength side of near-infrared light. That is, since there is little blurring due to chromatic aberration, deterioration of the captured image can be reduced even if mixed light of visible light and near infrared light is received.

  In the first embodiment, the switching device 130 for switching the IR cut filter 131 and the first optical filter 132 is arranged on the optical path, but the present invention is not limited to this. For example, instead of the switching device 130, a holding device that holds only the first optical filter may be arranged. By doing so, the resolution of the image of the bright subject is slightly lowered, but it is possible to capture both the bright subject and the dark subject without switching between the IR cut filter and the first optical filter. Specifically, for example, in a camera that is used for monitoring purposes in which a single imaging device captures a bright subject and a dark subject depending on the time of day, a blind spot for monitoring can be obtained without switching the optical filter between daytime and nighttime. Can be eliminated.

(Embodiment 2)
(About the configuration of the imaging device)
Next, a lens apparatus or an imaging apparatus according to the second embodiment will be described. In the lens device or the imaging device according to the second embodiment, the first optical filter that switches with the IR cut filter 131 in the switching device 130 blocks light having a wavelength different from that of the first optical filter 132 according to the first embodiment. To do. Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

(About the characteristics of the first optical filter)
Next, characteristics of the first optical filter 133 according to the second embodiment will be described. FIG. 7 is a characteristic diagram illustrating characteristics of the first optical filter according to the second embodiment. In FIG. 7, the vertical axis represents transmittance, and the horizontal axis represents wavelength. As shown in FIG. 7, the second optical filter 133 blocks light on the long wavelength side of near-infrared light. Specifically, the first optical filter 133 blocks light having a wavelength greater than an arbitrary wavelength, for example, of light having a wavelength of 900 nm to 1100 nm.

  The reason is that the wavelength of infrared light projected from a commonly used infrared LED projector is about 850 nm, and an object illuminated by the light projected from this infrared LED projector can be imaged. It is for doing so. In addition, since the light projected from the LED projector has a certain wavelength width, image degradation can be reduced by blocking light with a wavelength greater than 900 nm. In addition, some infrared LED projectors have a wavelength of about 950 nm of projected infrared light. For this reason, image degradation can be reduced by blocking light with a wavelength larger than 1000 nm in consideration of a certain wavelength width so that an object irradiated with infrared light having a wavelength of about 950 nm can be imaged. it can. In addition, for imaging an object irradiated with light from a light source having a wavelength longer than that of an LED projector, the sensitivity of imaging devices such as CCDs and CMOSs currently on the market is only up to light having a wavelength of 1100 nm. This is because the sensitivity to light of the above wavelengths is very low and the influence of image blur due to chromatic aberration is small.

  FIG. 8 is an explanatory diagram showing an axial spot image on the image plane of external light that has passed through the first optical filter according to the second embodiment. In FIG. 8, the case where the 1st optical filter 133 which interrupts | blocks the light with a wavelength larger than 900 nm is inserted is demonstrated. FIG. 8 shows the shortest wavelength (for example, 400 nm) on the short wavelength side of visible light among the light that passes through the first optical filter 133 and enters the image plane, and the boundary between visible light and near-infrared light. 2 shows an on-axis spot image of light having a wavelength (for example, 700 nm) and a longest wavelength (for example, 900 nm) on the long wavelength side of near-infrared light. As shown in FIG. 8, among the light incident on the image plane in FIG. 13, the shortest wavelength (for example, 400 nm) on the short wavelength side of visible light, the wavelength at the boundary between visible light and near-infrared light (for example, 700 nm), it can be seen that the range of each spot image is narrower than the range of the on-axis spot image of the light having the longest wavelength (for example, 1100 nm) on the long wavelength side of near-infrared light.

  According to the second embodiment, the same effect as in the first embodiment can be obtained.

(Embodiment 3)
(About the configuration of the imaging device)
Next, a lens apparatus or an imaging apparatus according to the third embodiment will be described. In the lens device or the imaging device according to the third embodiment, the first optical filter to be switched with the IR cut filter 131 in the switching device 130 is the first optical filter 132, 133 according to the first embodiment or the second embodiment. Blocks light of different wavelengths. Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

(About the characteristics of the first optical filter)
Next, characteristics of the first optical filter 134 according to the third embodiment will be described. FIG. 9 is a characteristic diagram illustrating characteristics of the first optical filter according to the third embodiment. In FIG. 9, the vertical axis represents the transmittance, and the horizontal axis represents the wavelength. As shown in FIG. 9, the first optical filter 134 blocks light on the short wavelength side of visible light and light on the long wavelength side of near infrared light. Specifically, the first optical filter 134 is, for example, a light having a wavelength less than an arbitrary wavelength among light having a wavelength of 450 nm or more and 650 nm or less and a wavelength greater than an arbitrary wavelength of light having a wavelength of 900 nm or more and 1100 nm or less. Block the light.

  The reason is the same as the reason described in the first and second embodiments.

(About the optimum characteristics of the first optical filter)
Next, optimum characteristics of the first optical filter according to the third embodiment will be described. FIG. 10 is a characteristic diagram illustrating optimum characteristics of the first optical filter according to the third embodiment. In FIG. 10, the vertical axis represents the transmittance, and the horizontal axis represents the wavelength. As shown in FIG. 10, the first optical filter 134 having an optimum characteristic blocks, for example, light having a wavelength of less than 550 nm and light having a wavelength of more than 900 nm.

  The reason is that when light with a wavelength of less than 550 nm is blocked, light on the short wavelength side half (for example, a wavelength range of 400 nm to less than 550 nm) can be blocked in the visible light wavelength range, thus improving chromatic aberration. This is because the deterioration of the image is suppressed. In addition, since an imaging element such as a CCD image sensor has high sensitivity to light having a wavelength of 550 nm or more and less than 600 nm, it is possible to suppress a significant decrease in luminance by transmitting light having a wavelength in this range. .

  Further, as described in the second embodiment, the wavelength of light emitted from a commonly used LED projector is about 850 nm, and light having a wavelength of 900 nm or more is considered in consideration of a certain wavelength width. This is because a relatively bright image can be taken even if the image is blocked, and deterioration of the image can be prevented.

  FIG. 11 is an explanatory diagram showing an axial spot image on the image plane of external light that has passed through the first optical filter according to the third embodiment. In FIG. 11, a case where the first optical filter 134 having the optimum characteristics shown in FIG. 10 is inserted will be described. FIG. 11 shows the shortest wavelength (for example, 550 nm) on the short wavelength side of visible light among the light transmitted through the first optical filter 134 having the optimum characteristics and incident on the image plane, visible light and near infrared light. The on-axis spot image of light having a wavelength at the boundary (for example, 700 nm) and the longest wavelength (for example, 900 nm) on the long wavelength side of near-infrared light is shown. As shown in FIG. 11, among the light incident on the image plane in FIG. 13, the shortest wavelength (for example, 400 nm) on the short wavelength side of visible light, the wavelength at the boundary between visible light and near-infrared light (for example, 700 nm), it can be seen that the range of each spot image is narrower than the range of the on-axis spot image of the light having the longest wavelength (for example, 1100 nm) on the long wavelength side of near-infrared light.

  Further, in FIG. 11, the shortest wavelength on the short wavelength side of the visible light, visible light, of the light incident on the image plane, compared to the axial spot images on the image plane shown in FIGS. It can be seen that the wavelength on the boundary between the light and the near-infrared light and the on-axis spot image of the light having the longest wavelength on the long-wavelength side of the near-infrared light are narrowed.

  According to the third embodiment, the same effects as those of the first or second embodiment can be obtained. Furthermore, according to the third embodiment, it is possible to capture an image with less chromatic aberration and less deterioration compared to the first or second embodiment.

(Embodiment 4)
(About the configuration of the imaging device)
Next, a lens apparatus or an imaging apparatus according to the fourth embodiment will be described. In the lens device or the imaging device according to the fourth embodiment, the switching device 130 includes the first optical filter 132 according to the first embodiment and the first optical filter 133 according to the second embodiment in addition to the IR cut filter 131. Alternatively, at least two or more of the first optical filters 134 according to the third embodiment are provided. Then, the switching device 130 switches according to the chromatic aberration of the lens device 110 and the purpose of use, and the IR cut filter 131, the first optical filter 132 according to the first embodiment, the first optical filter 133 according to the second embodiment, and the implementation. Any one of the first optical filters 134 according to the third embodiment is inserted into the optical path. Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

  According to the fourth embodiment, the same effects as those of the first to third embodiments can be obtained. Further, according to the fourth embodiment, the switching device 130 can be arranged in various types of lens devices or imaging devices having different chromatic aberrations and usage purposes.

  As described above, according to the filter holding mechanism, the lens device, and the imaging device, when shooting a bright subject, a color image is taken by inserting the IR cut filter 131, and when shooting a dark subject. The IR cut filter 131 is taken out from the optical path of the lens, and a filter for blocking the wavelength in a specific section between visible light and near infrared light is inserted and imaged. In this way, the chromatic aberration of visible light can be corrected in a video camera or a video camera lens apparatus, but the chromatic aberration from visible light to near-infrared light cannot be corrected sufficiently. Even in the case of imaging, since the wavelength range for imaging can be narrowed, the imaging light amount of the subject and the blind spot of the imaging wavelength can be reduced while reducing the blurring of the image due to chromatic aberration. Note that the wavelength range between visible light and near-infrared light that is blocked by the filter may be selected depending on the chromatic aberration of each lens and the purpose of use.

  As described above, the filter holding mechanism, the lens device, and the imaging device according to the present invention are useful for a video camera or a video camera lens device, and in particular, a video camera or a video camera lens used for surveillance purposes. Suitable for equipment.

DESCRIPTION OF SYMBOLS 100 Imaging device 110 Lens apparatus 111 Optical path 120 Imaging device main body 121 Imaging element 130 Switching device 131 IR cut filter 132 1st optical filter

Claims (8)

A first optical filter that blocks some wavelengths in a wavelength range from visible light to near infrared light and transmits at least some wavelengths of visible light and at least some wavelengths of near infrared light When,
A holding unit for holding the first optical filter on the optical path;
A filter holding mechanism characterized by comprising:   The filter holding mechanism according to claim 1, further comprising a switching unit that switches between the first optical filter and a second optical filter that blocks near-infrared light.   3. The filter holding mechanism according to claim 1, wherein the first optical filter blocks a part of wavelengths on a short wavelength side of visible light.   3. The filter holding mechanism according to claim 1, wherein the first optical filter blocks a part of wavelengths on the long wavelength side of near infrared light. 4.   3. The filter according to claim 1, wherein the first optical filter blocks a part of wavelengths on a short wavelength side of visible light and a part of wavelengths on a long wavelength side of near-infrared light. Retention mechanism.   The switching unit, as the first optical filter, is an optical filter that blocks some wavelengths on the short wavelength side of visible light, an optical filter that blocks some wavelengths on the long wavelength side of near infrared light, or visible Switching between any one of the optical filters that cut off some wavelengths on the short wavelength side of light and some wavelengths on the long wavelength side of near-infrared light, and the second optical filter, The filter holding mechanism according to claim 2. A filter holding mechanism having an optical filter according to claim 1,
A plurality of lenses that allow external light to enter the optical filter;
With
The lens device according to claim 1, wherein the filter holding mechanism is arranged on any one of an object side of the lens, a space between the lenses, or a rear side of the lens. A filter holding mechanism having an optical filter according to claim 1,
A photoelectric conversion element for imaging;
A lens device having a plurality of lenses that allow external light to enter the photoelectric conversion element via the optical filter;
An imaging apparatus comprising:

Images