JP4072977B2 - TV lens with still shooting function - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a television lens with a still photographing function, and more particularly to a television lens with a still photographing function that can be attached to a camera body such as a broadcast television camera and can insert a so-called extender lens.
[0002]
[Prior art]
Generally, in a television camera for broadcasting, etc., a three-color separation prism and a CCD corresponding to each color light for obtaining subject information by each separated color light are mounted on the television camera body in order to obtain a high-quality color image. In addition, various lenses according to applications such as a zoom lens can be attached to the front stage of the TV camera body.
[0003]
By the way, while we are doing sports television broadcasts or wedding reception video shooting, for example, highlight scenes such as scoring goal scenes and wedding cake cutting scenes, including their video cameras (including video cameras; the same applies below) Therefore, there is a desire to electrically record as a still image.
In response to such a request, it is conceivable to use a single frame of a moving image electrically captured by a television camera as a still image. However, in the case where priority is given to compatibility with the current NTSC signal, in this way. The obtained still image has a reduced image quality.
[0004]
[Problems to be solved by the invention]
Therefore, an image system dedicated to still images is attached to the TV lens unit or the TV camera body, and the image quality is improved by obtaining a still image with an image capturing system different from the TV image capturing system. It is desirable to reduce the overall size and cost of the apparatus by using a part of it for the still image capturing system.
[0005]
However, when trying to share the lens unit between the TV image capturing system and the still image capturing system, it is necessary to divide the light beam using a reflection mirror or the like, or to switch the traveling direction of the light beam, but using the existing lens unit On the other hand, it is not always easy to provide a space on the optical axis where a beam splitting unit such as a reflection mirror or a beam direction switching unit can be inserted.
[0006]
The present invention has been made to solve such a problem. When a still image shooting function is added to a television lens, the television image capturing system and a part of the optical system of the still image capturing system are shared. An object of the present invention is to provide a television lens with a still photographing function that can easily secure a space for inserting a light beam splitting means or a light beam direction switching means for guiding an incident light flux to both systems.
[0007]
[Means for Solving the Problems]
The television lens with a still photographing function of the present invention is a television lens having a lens system attached to the front stage of the television camera body and having a space in which a focal length conversion lens group can be inserted.
A reflection mirror for guiding a light beam carrying subject image information to a still image pickup device arranged in a direction different from that of the TV camera body is inserted at a position between the lenses of the lens system in which the focal length conversion lens group is inserted. It is comprised so that it may be performed.
[0008]
In addition, it is preferable that the reflection mirror and the focal length conversion lens group are configured to be switchably inserted into the inter-lens position.
Further, the reflection mirror and the focal length conversion lens group are mounted on one plate-like member, and an insertion switching operation of the reflection mirror and the focal length conversion lens group to the inter-lens position is performed on the plate-like member. It is preferably made by a turning operation or a sliding operation.
[0009]
The reflecting mirror is preferably a half mirror.
Furthermore, it is preferable that the reflection mirror is a total reflection mirror, and the plate-like member is provided with the total reflection mirror, the focal length conversion lens group, and a through hole.
In addition, a still image lens unit made of the same material and material as the lens unit located at the latter stage of the inter-lens position in the lens system is disposed between the reflection mirror and the still image imaging device. It is preferable to install.
Further, in the case where the TV camera body is provided with a color separation prism for color-separating a light beam carrying subject information, it is provided between the still image lens unit and the still image imaging device. It is preferable to provide an optical prism that gives an optical path length substantially equivalent to the optical path length of the light beam incident on the color separation prism to the light beam incident on the still image pickup device.
In this case, it is preferable that the optical prism has a function of returning the reversal of the image posture by the reflection mirror.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing a television lens with a still photographing function of the present invention. That is, the television lens with a still photographing function is mounted between the zoom lens group 21 and the television lens system 2 having the zoom lens group 21 that is attached to the subject side of the television camera body 1 on which the color separation prism 11 is mounted. A still image imaging system 3 for capturing a still image (hereinafter referred to as a still image) by taking in a light beam reflected by a total reflection mirror 31 arranged in a freely accessible manner, and a focal length conversion lens group (hereinafter referred to as an EXT group). ) 4.
The total reflection mirror 31 and the EXT group 4 are configured to be arranged exclusively on the optical axis X of the zoom lens group 21.
[0011]
Next, each part mentioned above is demonstrated in detail using FIG.
First, the television camera body 1 has a color separation prism 11 that splits a light beam carrying subject image information that has passed through the television lens system 2 into three primary color lights, and B, R, and G separated by the color separation prism 11. Imaging elements 12, 13, and 14 comprising CCDs corresponding to the respective primary color lights are formed.
[0012]
The color separation prism 11 is a combination of three prisms 11A, 11B, and 11C. That is, the first prism 11A, the second prism 11B, and the third prism 11C are arranged in order from the television lens system 2 side along the optical axis of the television lens system 2, and the first prism 11A and the second prism 11B have an air gap. A first dichroic layer that reflects only blue light is formed on the second prism facing surface of the first prism 11A, and the second prism 11B and the third prism 11C are made of red light. It is joined via a second dichroic layer that reflects only the light. As a result, the light beam incident on the first prism 11A is separated into B, R, and G3 primary color light by the color separation prism 11, and the B, R, and G spectral characteristics are further emitted on the exit surfaces of the prisms 11A, 11B, and 11C. Trimming filters 11A ′, 11B ′, and 11C ′ for trimming are joined to irradiate the image pickup devices 12, 13, and 14 corresponding to the respective color lights, and subject images of the respective color lights on these image pickup devices 12, 13, and 14. Is imaged.
[0013]
Further, a filter member 15 such as a low-pass filter and / or an infrared cut filter is disposed in the vicinity of the light incident end face of the first prism 11A.
In the imaging elements 12, 13, and 14 in which the subject images of the respective color lights are formed in this manner, the subject image information carried by the respective color lights is photoelectrically converted at a predetermined sampling period, and then the electric power for each color is obtained. The signals are combined to form a color television image of the subject.
[0014]
On the other hand, the television lens system 2 includes a zoom lens group 21 composed of five groups.
The zoom lens group 21 includes, in order from the object side, a positive first group having a focusing function including four lenses, a negative second group including three lenses having a zooming function, and this zooming. Negative third group consisting of two lenses for correcting the fluctuation of the focal position due to the above, a fourth group consisting of a front group of positive relay lenses having four lenses, and a positive group having six lenses. The fifth lens group consisting of the rear group of the relay lens is disposed, and both lens groups are moved along the optical axis X while changing the distance between the second lens group and the third lens group at the time of zooming. The focal length f of the entire system is changed, and the light beam is efficiently focused on the imaging position.
[0015]
In the zoom lens group 21, a shutter (aperture) 22 is disposed between the third group and the fourth group.
The fourth group and the fifth group are originally arranged at a large interval so that an EXT group that shifts the focal length of the zoom lens group 21 to the telephoto side can be inserted. Focusing on the fact that there is a large space in the EXT group insertion portion, the insertion space for the total reflection mirror 31 is secured.
[0016]
In the present embodiment, the total reflection mirror 31 can be inserted in the EXT group insertion space between the fourth group and the fifth group so as to be switchable with the EXT group 4.
[0017]
That is, the EXT group 4 and the total reflection mirror 31 are arranged on a turret plate 45 as shown in FIG. 3, and the turret plate 45 is rotatable in the direction of arrow B about the center 47a of the rotation shaft 47. ing. The turret plate 45 is formed with a through hole 46, and the position of the through hole 46, the position of the EXT group 4, and the position of the total reflection mirror 31 are arranged on the turret plate 45. So that they are equiangular with each other and at an equal distance d from the center of rotation.
[0018]
The rotation shaft 47 of the turret plate 45 is arranged at a position shifted by a distance d with respect to the optical axis X of the zoom lens group 21, and according to the rotation of the rotation shaft 47, the through hole 46, the EXT group 4 and The total reflection mirror 31 is positioned on the optical axis X, and the turret plate 45 is held at that position.
[0019]
The turret plate 45 is covered with a cover member 40 as shown in FIG. 4, and can be rotated by operating a turret plate operation lever 42 arranged outside the cover member 40. When a normal magnification is sufficient as a zoom magnification for capturing an image, the through-hole portion 46 is used. When a high magnification is desired, the EXT group 4 is selected. When a still image is desired to be captured, the total reflection mirror 31 is selected. The zoom lens group 21 is operated so as to be positioned on the optical axis X.
[0020]
Further, as shown in FIG. 5, a through-hole portion 44 is disposed below the cover member 40, the turret plate 45 is rotated, and the total reflection mirror 31 is positioned on the optical axis of the zoom lens group 21. When squeezed, the light beam carrying the subject image information is reflected by the total reflection mirror 31 (tilted at 45 ° with respect to the light beam) and passes through the through hole 44 as shown in FIG. Then, the light enters the lens barrel 3a of the still image pickup system 3 provided adjacent to the lower portion of the cover member 40.
[0021]
The still image pickup system 3 includes a still image pickup lens group 32, a right-angle prism 33 that re-reflects the subject image reflected by the total reflection mirror 31, and restores the image posture, a low-pass filter and / or an infrared cut filter, and the like. The filter member 34 and an image sensor 35 composed of a CCD for capturing a still image are provided.
[0022]
By the way, the zoom lens group 21 of the television lens system 2 and the optical system such as the color separation prism 11 in the television camera body 1 are designed so as to reduce aberrations as a whole, and the image pickup devices 12 and 13. , 14 so that the image quality formed on the image 14 is good.
Therefore, when the light beam is deflected by the total reflection mirror 31 and taken into the still image pickup system 3, the aberration is deteriorated as it is, and it is difficult to improve the image quality formed on the image pickup device 35. Become.
[0023]
Therefore, in the present embodiment, in the still image pickup system 3, a still image pickup lens group having the same configuration (the same number of lenses, lens shape, and lens material) as that of the fifth group is provided after the total reflection mirror 31. 32, and a right angle prism 33 for providing the light beam with an optical path length substantially the same as the optical path length in the color separation prism 11 when the light beam passes through the color separation prism 11. Even when a still image is picked up by the still image pickup system 3, the aberration is corrected as well as when a TV image is picked up by the TV image pickup system so that a high-quality reproduced image can be obtained. Yes.
[0024]
That is, the first group, the second group, the third group, the fourth group, the fifth group and the color separation prism 11 constituting the optical system of the television image capturing system, and the first group and the first group constituting the still image capturing system. The second group, the third group, the fourth group, the still imaging lens group 32 and the right-angle prism 33 are equivalent in terms of optical characteristics, and the imaging elements 12, 13, and 14 of the television image imaging system and the still image imaging system 3 are imaged. The aberration of the image on the element 35 is the same.
[0025]
Further, as described above, the fifth group of the zoom lens group 21 and the still imaging lens group 32 are configured so that the number of lenses, the lens shape, and the lens material are exactly the same. Therefore, it is possible to reduce the manufacturing process and the manufacturing cost.
In addition, by reflecting the light beam by the reflecting prism 33 in the still image pickup system 3, the image reflected by the total reflection mirror 31 can be inverted again and again, and on the image pickup devices 12, 13, and 14 of the television image pickup system. It is possible to match the image orientation on the image sensor 35 on the image sensor 35 of the still image capturing system 3.
[0026]
Note that the television lens with a still photographing function of the present invention is not limited to that of the above-described embodiment, and various other modes can be changed. For example, instead of the above-described turret plate 45, FIG. As shown in FIG. 6, a slide plate 50 slidable in the direction of arrow C may be disposed at the above-described EXT group insertion space position.
[0027]
In the illustrated state, a through hole 46 (not shown in FIG. 6) is arranged at the position of the optical axis X of the television lens system 2. From this state, the slide plate 50 is moved to the arrow C. It is possible to place the EXT group 4 or the total reflection mirror 31 at the position of the optical axis X by sliding in the direction.
When the total reflection mirror 31 is disposed at the position of the optical axis X, as in the case of using the turret plate 45 described above, the light beam incident on the television lens system 2 is captured as a still image below the slide plate 50. It can be guided into the lens barrel 3a of the system 3.
[0028]
Similarly to the case where the turret plate 45 is used, the slide plate 50 may be entirely covered by a cover member having an appropriate shape.
It should be noted that the arrangement positions of the right-angle prism 33 and the filter member 34 can be interchanged.
[0029]
Further, a half mirror may be used instead of the total reflection mirror. When the reflecting mirror is a half mirror, the through hole 46 shown in FIG. 3 is not necessarily provided.
The right-angle prism 33 described above has a function of reflecting the light beam and reversing the image posture upside down. However, the right angle prism 33 is placed on the image sensor 35 with the image posture reversed by the reflection mirror 31 in the TV lens system 2. When it is desired to form an image or when image information captured by the image sensor 35 is electrically inverted, a glass block in which the optical path length of the right-angle prism 33 is equal to that of the right-angle prism 33 is used instead of the right-angle prism 33. May be provided so that the light beam travels straight and passes through the glass block.
[0030]
【The invention's effect】
As described above, according to the television lens with a still photographing function of the present invention, the reflection mirror is inserted into the EXT group insertion space in which the lens interval of the television lens attached to the television camera body is wide, and is deflected by this reflection mirror. The TV image and still image can be taken with a single TV camera device without changing the design of the TV lens and separately securing the space for inserting the reflection mirror. Can be convenient.
[0031]
If the reflection mirror and the EXT group are switchably positioned on the optical axis of the television lens, it is convenient to increase the magnification of the television lens and to take a still image as necessary.
In addition, by sharing a part of the lens portion of the TV image pickup system and the still image pickup system, the entire apparatus can be made compact and inexpensive, and the image pickup element of the still image pickup system can be replaced with the image pickup element of the TV image pickup system. The image quality of a still image can be made favorable by providing separately.
[0032]
Further, in the still image capturing system, a lens portion having the same configuration as that of the lens portion disposed in the rear stage of the reflecting mirror of the television image capturing system that is not shared by both the systems is provided in the camera body. If the optical block that gives the passing light beam an optical path length substantially equal to the color separation prism of the television image capturing system is provided in the still image capturing system, the optical characteristics of the still image capturing system can be obtained. It is possible to make the aberrations of both systems good.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a television lens with a still photographing function according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the TV lens system shown in FIG. 1 in more detail. FIG. 3 is an embodiment shown in FIG. FIG. 4 is a schematic view showing a shape of an outer side portion of the embodiment shown in FIG. 1. FIG. 5 is a partially cutaway view showing an operation of the embodiment shown in FIG. Schematic front view showing an embodiment different from the embodiment shown in FIG.
DESCRIPTION OF SYMBOLS 1 TV camera body 2 TV lens system 3 Still image pickup system 3a Lens barrel 4 Focal length conversion lens group (EXT group)
11 Color separation prisms 11A, 11B, 11C Prism 12, 13, 14, 35 Image sensor 21 Zoom lens group 22 Shutter (aperture)
31 Total Reflection Mirror 32 Still Imaging Lens Group 33 Right Angle Prism 40 Cover Member 42 Turret Plate Operation Lever 45 Turret Plates 44, 46 Through Hole 47 Rotating Shaft 50 Slide Plate

Claims (8)

In a television lens having a lens system attached to the front stage of the television camera body and having a space in which a focal length conversion lens group can be inserted,
A reflection mirror for guiding a light beam carrying subject image information to a still image pickup device arranged in a direction different from that of the TV camera body is inserted at a position between the lenses of the lens system in which the focal length conversion lens group is inserted. A television lens with a still photographing function, characterized in that it is configured as described above.   2. The television lens with a still photographing function according to claim 1, wherein the reflection mirror and the focal length conversion lens group are configured to be switchably inserted into the inter-lens position.   The reflection mirror and the focal length conversion lens group are mounted on one plate-like member, and an insertion switching operation of the reflection mirror and the focal length conversion lens group to the inter-lens position rotates the plate-like member. The television lens with a still photographing function according to claim 2, wherein the television lens is operated by an operation or a slide operation.   The television lens with a still photographing function according to any one of claims 1 to 3, wherein the reflecting mirror is a half mirror.   4. The still according to claim 3, wherein the reflection mirror is a total reflection mirror, and the plate-like member is provided with the total reflection mirror, the focal length conversion lens group, and a through hole. TV lens with shooting function. Between the reflection mirror and the still image pickup device, a still image lens unit formed of the same shape and the same material as the lens unit located at the subsequent stage of the inter-lens position in the lens system is disposed. The television lens with a still photographing function according to any one of claims 1 to 5, wherein the television lens has a still photographing function. The television camera body is provided with a color separation prism for color-separating a light beam carrying subject information, and the still image lens is interposed between the still image lens unit and the still image imaging device. 7. An optical prism that provides an optical path length substantially equivalent to an optical path length of the light beam incident on the color separation prism in the prism with respect to the light beam incident on the image sensor. TV lens with still photography function. 8. The television lens with a still photographing function according to claim 7, wherein the optical prism has a function of returning the reversal of the image posture by the reflecting mirror.

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