JP2006215283A - Imaging apparatus for detecting focus state - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus for detecting a focus state capable of realizing autofocus, for example, by detecting a focus state based on the contrast of a subject image picked up by a plurality of imaging surfaces of an imaging device for detecting a focus state arranged at positions in different optical path length, and capable of easily changing the difference of the optical path length of the imaging surface to the appropriate one in accordance with the range of a focal distance where the kind and the focus state of a photographic lens are to be satisfactorily detected by making a block for changing the difference of the optical path length of the imaging surface of the imaging device for detecting the focus state exchangeable. <P>SOLUTION: By attaching an adapter 30 for detecting a focus state between a camera 10 and the photographic lens 14, the focus state is detected (AF of optical path length difference system). A CCD block 42 of the adapter 30 where the CCDs 64A and 64B are arranged can be changed so that the imaging surface has the desired difference of the optical path length. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus for focus information detection, and more particularly to an imaging apparatus for focus state detection that captures an image for detecting a focus state in autofocus (AF) of an optical path length difference method.

  As an autofocus (AF) suitable for a video camera such as a television camera for broadcasting, an AF method called an optical path length difference method has been proposed (see, for example, Patent Document 1). In this optical path length difference type AF, for example, a light splitting optical system (light splitting means) such as a half mirror is provided in the main line optical path in which the subject light incident on the photographing lens is guided to the camera image pickup device (image pickup device). The subject light in the main light path is divided into subject light that travels in the main light path and subject light that travels in the focus state detection optical path branched from the main light path.

  In the focus state detection optical path, a plurality of image pickup surfaces of an image pickup element (focus state detection image pickup element) arranged for focus state detection are arranged with an optical path length difference. For example, a light-splitting optical system that further divides subject light into two parts is arranged in the focus state detection optical path, and a focus state detection image sensor is provided in each optical path along which each subject light divided by the light-splitting optical system travels. Be placed. Then, the imaging surfaces of the focus state detection imaging elements are arranged at positions where the optical path length is shortened by an equal distance with respect to the imaging surface of the video imaging element and at positions where the imaging path becomes longer. Note that the plurality of imaging surfaces having the optical path length difference of the focus state detection imaging element are not limited to being configured by different imaging elements, and a plurality of imaging images formed so as to have the optical path length difference in the same imaging element. In some cases, it is composed of surfaces.

  The video signal (subject image) obtained from each focus state detection imaging device is processed by a predetermined signal processing unit, and a focus evaluation value indicating the magnitude of the contrast of the subject image captured on the imaging surface is calculated. Is done. The subject image picked up on the image pickup surface of each focus state detection image pickup device is picked up by the image pickup device of the camera when the focus of the image pickup lens is slightly moved to the close side and the infinity side with respect to the current position. Therefore, the focus state (focus, front pin, rear pin) at the current position of the photographic lens is detected by comparing the focus evaluation values indicating the contrast. Focusing is automatically performed by controlling the focus of the photographic lens based on the focus state.

  Patent Document 2 proposes a focus state detection adapter that enables the above-described optical path length difference type AF in a photographic lens not equipped with an AF function. According to this, the focus state detection adapter is mounted between the photographing lens and the camera, and the light splitting means inserted into the main line optical path and the light disposed in the focus state detection optical path are attached to the adapter. A dividing unit, an imaging device for detecting a focus state, and the like are arranged.

The focus state information detected as described above can be used not only for the optical path length difference AF but also for other uses such as displaying focus information.
JP 2002-365517 A JP 2002-296492 A

  By the way, the appropriate optical path length difference of the imaging surface of the focus state detection imaging device varies depending on the focal length of the photographing lens. For example, when the subject image captured by each of the two imaging surfaces of the focus state detection imaging element having a certain optical path length difference is displaced by a predetermined amount from the current position to the near side and the infinity side This corresponds to a subject image captured by a video image sensor of the camera. At that time, the smaller the focal length of the photographing lens, the larger the displacement amount of the focus. The larger the focal length of the photographing lens, the smaller the displacement amount of the focus. In a situation where the amount of focus displacement is too large, the subject images on both the near side and the infinity side are greatly out of focus, or at least one of the focus images is greatly out of focus, so the contrast of those subject images The (focus evaluation value) cannot be compared effectively, and the focus state cannot be detected. Conversely, in situations where the amount of focus displacement is too small, there is almost no difference between the subject images on the near side and the infinite edge side. In this case as well, the contrast (focus evaluation value) of those subject images can be effectively compared. Therefore, the focus state cannot be detected.

  Therefore, when the optical path length difference of the imaging surface of the imaging device for focus state detection is fixed, there is a focal length range in which the focus state can be detected well, and the focal length of the photographing lens is variable The optical path length difference is set so that the focus state can be detected well over the entire range, or the focal length variable range is so large that the focus state cannot be detected well over the entire range. In this case, it is necessary to set the optical path length difference depending on which range the focus state can be detected satisfactorily.

  However, when the AF function is added to the photographic lens by an adapter as in Patent Document 2, the focus state detection in the adapter is performed according to the variable range of the focal length in the photographic lens to which the adapter is attached. Since it is necessary to set the optical path length difference of the imaging surface of the image pickup device for an image sensor, there is a problem that the types of photographing lenses that can use the adapter in which the optical path length difference is set are limited to specific ones. . Therefore, the user must prepare an adapter for each type of photographing lens owned (for each focal length range in which the focus state can be detected well), resulting in an operational cost burden.

  Further, not only in the case of an adapter, but also in the case where the above-described focus state detection optical path and focus state detection image sensor are incorporated in the photographic lens, the focus is not limited to the entire variable range of the focal length of the photographic lens. When the state cannot be detected satisfactorily, it may be desired to change the focal length range in which the focus state can be satisfactorily detected according to the shooting situation or the like. For example, if you want to change the focal length variable range that can detect the focus state well to match the focal length range that you plan to use for each shooting, or you want to change it to match the focal length range that you plan to use AF for There is a case. If the zoom is set to the tele side, AF is used. If the zoom is set to the wide side, if the AF cannot be used and manual focus is acceptable, the focal length when the zoom is on the tele side is used. At the same time, the optical path length difference of the imaging surface of the focus state detection image sensor is increased, and in the opposite case, the optical path length difference of the imaging surface of the focus state detection image sensor is decreased according to the focal length when the zoom is at the wide side. Change is required. Conventionally, there has been a problem that the optical path length difference of the imaging surface of the focus state detection imaging element cannot be easily changed in response to such a request.

  The present invention has been made in view of such circumstances, and the optical path length difference of the imaging surface of the imaging device for focus state detection is determined according to the focal length range in which the type of the photographing lens or the focus state is to be detected satisfactorily. An object of the present invention is to provide an imaging device for focus state detection that can be easily changed to an appropriate size.

  In order to achieve the object, an imaging device for detecting a focus state according to claim 1 irradiates a subject light incident on an imaging surface of a video imaging element of a camera after entering a photographing lens and passing through a main optical path. Dividing by the dividing means, one subject light obtained by the division is guided to a focus state detection optical path different from the main optical path, and the focus state detection is arranged at a position where the optical path length of the focus state detection optical path is different. In the focus state detection imaging apparatus that enters a plurality of imaging surfaces of the image pickup device and picks up a subject image for detecting the focus state of the photographing lens by each of the plurality of imaging surfaces, the focus state detection optical path An imaging device for focusing state detection constituting a plurality of imaging planes arranged on the camera can be attached to and detached from the focusing state detection optical path as an integral block, and the focusing state detection imaging A plurality of the imaging surface of the device is characterized in that the desired configuration has been said block such that the optical path length difference has to be able to mount the focus state detection optical path.

  According to the present invention, the optical path length difference of the plurality of imaging surfaces of the imaging device for focus state detection can be easily set to an appropriate size according to the focal length range in which the type of photographing lens and the focus state are to be detected satisfactorily. Can be changed.

  According to a second aspect of the present invention, there is provided the focus state detection imaging apparatus according to the first aspect, wherein the plurality of imaging planes of the focus state detection imaging element are imaging planes of different imaging elements, respectively. It is characterized in that it is arranged on the optical path through which each subject light divided by the light dividing means arranged in the state detection optical path passes. In the case where the plurality of imaging surfaces are not configured by a single imaging device, a light dividing unit that divides subject light into each imaging surface is required.

  The focus state detection imaging apparatus according to claim 3 is the invention according to claim 2, wherein the block includes the focus state detection image sensor, and a light splitting unit disposed in the focus state detection optical path. It is characterized by having. By configuring the light splitting means that divides subject light on each imaging surface and the focus state detection image sensor as an integral block, it can be easily changed to the desired optical path length difference by replacing the block. It is.

  According to a fourth aspect of the present invention, in the focus state detection imaging apparatus according to the first, second, or third aspect of the invention, the light splitting unit disposed in the main line optical path is attached and detached between the photographing lens and the camera. It is characterized by being placed on an adapter that can be mounted. The present invention is limited to an aspect in which the focus state can be detected by attaching an adapter (attached device) to the photographing lens, and the block is detachably attached to the adapter.

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the adapter includes a detecting unit that detects a type of a mounted photographic lens, and the block that matches the detected type. It is characterized by comprising display means for displaying the type. According to the present invention, since the block type that matches the type of the photographic lens with the adapter attached is displayed, the user can easily select an appropriate block.

  According to the imaging device for focus state detection according to the present invention, the optical path length difference of the imaging surface of the imaging device for focus state detection is appropriately set according to the type of the photographing lens or the focal length range where the focus state is to be detected satisfactorily. It can be easily changed to a large size.

  Hereinafter, preferred embodiments of an imaging device for detecting a focus state according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side view showing an external appearance of a television camera system in which an adapter (focus state detection adapter) according to the present invention is configured as an adapter (focus state detection adapter). In FIG. 1, a camera (camera body) 10 captures an image to be recorded or reproduced for broadcasting, and outputs the image as a video signal of a predetermined format or records it on a recording medium (imaging image sensor). And a portable ENG camera equipped with necessary processing circuits. The camera 10 is provided with a bayonet mount 12 for mounting the photographing lens 14 in the normal case. In the system shown in FIG. 1, the bayonet mount 12 allows the autofocus described later. A focus state detection adapter 30 is attached to the front surface of the camera 10.

  On the other hand, a bayonet mount 32 similar to that of the camera 10 is provided on the front side of the focus state detection adapter 30, and the taking lens 14 is attached to the front of the focus state detection adapter 30 by the bayonet mount 32. Yes.

  A focus ring for focus adjustment, a zoom ring for zoom adjustment, and an iris ring for aperture adjustment, which are not shown in the figure, are rotatably disposed around the lens barrel of the photographic lens 14. A drive unit 16 for rotating these operation rings by a built-in motor is mounted on the part. The drive unit 16 and the focus state detection adapter 30 are connected by a cable 34 so that various types of information can be exchanged.

  As described above, the focus state detection adapter 30 can be detachably mounted between the camera 10 and the photographing lens 14, so that auto focus (AF) described later can be used. Yes. Note that the focus state detection adapter 30 (the focus state detection imaging apparatus according to the present invention) is not limited to the case where AF is enabled, but when the focus state is detected such as when the focus state information is displayed. Although it can be used, in this embodiment, it is used to enable AF.

  At the time of AF, the drive unit 16 detects the focus state of the photographic lens 14 based on information obtained from the focus state detection adapter 30, and rotationally drives the focus ring based on the focus state to thereby move the focus lens in the lens barrel. The focus lens is moved back and forth in the optical axis direction, and the focus of the photographic lens is automatically adjusted to focus on the photographic subject.

  The focus state detection adapter 30 includes a main body 40 and a CCD block 42, and the CCD block 42 is detachably attached to the main body 40. As will be described later, the CCD block 42 is equipped with two CCDs (focus state detection CCDs) having imaging surfaces at positions where the optical path lengths are different in order to capture images for AF (for focus state detection). Depending on the type of the photographic lens 14 and the like, the CCD block 42 having an appropriate difference in optical path length can be replaced with the main body 40. Further, a display unit 44 such as an LCD is disposed on the side surface of the housing of the main body unit 40. For example, information indicating the type of CCD block suitable for the type of the photographing lens 14 is displayed on the display unit 44. It has become so.

  FIG. 2 is a diagram showing the configuration of the optical system of the television camera system configured as shown in FIG. As shown in the figure, a focus lens (group) FL, a zoom lens (group) ZL, an iris I, and a relay lens (group) RL are arranged in order along the optical axis O of the main optical path in the lens barrel of the photographing lens 14. Has been. The focus lens FL and zoom lens ZL move back and forth along the optical axis O in conjunction with the rotation of the focus ring and zoom ring by the motor of the drive unit 16 or manually. When the lens FL moves, the focus position (object distance to be in focus) changes, and when the zoom lens ZL moves, the zoom magnification (focal length) changes. When the iris ring is rotated by the motor of the drive unit 16 or manually, the iris I opens and closes in conjunction with the iris ring, and the opening amount changes.

  A half mirror (light splitting optical system) 60 inserted at an angle of approximately 45 degrees on the optical axis O is disposed in the main body portion 40 of the focus state detection adapter 30 disposed on the rear side of the photographing lens 14. The half mirror 60 branches the focus state detection optical path along the optical axis O ′ substantially orthogonal to the optical axis O of the main optical path. The half mirror 60 is not limited to one that equally divides the amount of incident light into transmitted light and reflected light.

  The camera disposed on the rear side of the main body 40 of the focus state detection adapter 30 has color separation that separates incident subject light into three wavelengths of red (R), green (G), and blue (B). An optical system 50 and image pickup elements (for example, CCDs) 52 for R, G, and B that pick up images of subject light of each color separated are disposed. Note that the R, G, and B image pickup elements arranged at the positions of optically equivalent optical path lengths are represented by a single image pickup element 52 as shown in FIG.

  The subject light that has entered the photographic lens 14 and passed through the focus lens FL, zoom lens ZL, iris I, and relay lens RL subsequently enters the main body 40 of the focus state detection adapter 30 and is transmitted by the half mirror 60. It is divided into light and reflected light. The subject light transmitted through the half mirror 60 travels as it is along the main optical path of the optical axis O and enters the camera 10. Then, it is color-separated by the color separation optical system 50 and enters the image pickup surface of the image pickup device 52 for each color. A subject image formed by subject light incident on the imaging surface of the image pickup device 52 is photoelectrically converted by the image pickup device 52 and subjected to signal processing by a predetermined signal processing circuit of the camera 10. As a result, a video signal for recording or reproduction is generated.

  The CCD block 42 of the focus state detection adapter 30 is provided with a cube-type beam splitter 62 and two CCDs (focus state detection CCDs) 64A and 64B. The subject light (focus state detection subject light) reflected by the half mirror 60 of the main body 40 and guided to the focus state detection optical path on the optical axis O ′ is incident on the beam splitter 62 of the CCD block 42, The half mirror surface 62M divides the light into reflected light and transmitted light having the same light quantity. The subject light reflected by the half mirror surface 62M enters the imaging surface of one focus state detection CCD 64A, and the subject light transmitted through the half mirror surface 62M enters the imaging surface of the other focus state detection CCD 64B. The focus state detection CCDs 64A and 64B may be image pickup devices other than the CCD.

  FIG. 3 is a view showing the relationship between the optical path lengths of the respective imaging surfaces, with the image pickup element 52 of the camera 10 and the focus state detection CCDs 64A and 64B of the focus state detection adapter 30 shown on the same optical axis. . As shown in the figure, the optical path length of subject light incident on the imaging surface of one focus state detection CCD 64A is set shorter than the optical path length of subject light incident on the imaging surface of the other focus state detection CCD 64B. The optical path length of the subject light incident on the imaging surface of the image pickup device 52 is set to be an intermediate length. That is, the imaging surfaces of the pair of focus state detection CCDs 64 </ b> A and 64 </ b> B are arranged so as to be at a position equidistant from the imaging surface of the imaging device 52 for video.

  In this way, the pair of focus state detection CCDs 64A and 64B is equivalent to the case where the subject light incident on the photographing lens 14 is imaged on the imaging surface at an equidistant position before and after the imaging surface of the image pickup device 52 for video. Video signals can be obtained. The focus state detection CCDs 64A and 64B do not need to capture color images, and in the present embodiment, monochrome image signals (luminance signals) are acquired from the focus state detection CCDs 64A and 64B. .

  FIG. 4 is a block diagram showing a configuration of a control system mainly mounted on the main body 40 of the focus state detection adapter 30 and a configuration of a control system for executing AF mounted on the drive unit 16. First, the components related to the AF will be described. In the figure, a focus evaluation value detection unit 70, a CPU 80, and the like are mounted on the main body 40 of the focus state detection adapter 30, and the focus state detection adapter 30 is provided. A video signal of a video (subject image) captured by the focus state detection CCDs 64 </ b> A and 64 </ b> B arranged in the CCD block 42 is input to the focus evaluation value detection unit 70. The video signal obtained from the focus state detection CCD 64A is called a chA video signal, and the video signal obtained from the focus state detection CCD 64B is called a chB video signal.

  The focus evaluation value detection unit 70 includes an A / D converter 72A for processing the chA video signal, a high-pass filter (HPF) 74A, a gate circuit 76A, an adder circuit 78A, and an A for processing the chB video signal. It comprises a / D converter 72B, a high-pass filter (HPF) 74B, a gate circuit 76B, and an adder circuit 78B. Since the circuits 72A to 78A for processing the chA video signal and the circuits 72B to 78B for processing the chB video signal are subjected to the same processing, the circuits 72A to 72A for the chA video signal are processed. Explaining only the processing of 78A, the chA video signal input to the focus evaluation value detection unit 70 is first converted into a digital signal by the A / D converter 72A. Next, only the high frequency component signal is extracted from the video signal by the HPF 74A. The video signal of the high frequency component is subsequently input to the gate circuit 76A, and only the video signal within a range corresponding to a predetermined AF area (for example, a rectangular area at the center of the screen) set within the shooting range (screen) is obtained. Extracted. Then, the video signal in the AF area extracted by the gate circuit 76A is input to the adding circuit 78A and integrated by one field (one screen).

  The integrated values obtained by the adder circuits 78A and 78B in this way are focus evaluation values indicating the level of contrast of the subject images captured by the focus state detection CCDs 64A and 64B, and are read into the CPU 80, respectively. The focus evaluation value obtained from the chA video signal is called a chA focus evaluation value, and the focus evaluation value obtained from the chB video signal is called a chB focus evaluation value.

  A CPU 90 is mounted on the drive unit 16, and the CPU 90 and the CPU 80 of the focus state detection adapter 30 can communicate with each other by a communication circuit (not shown). The CPU 80 of the adapter 30 transmits the focus evaluation values of chA and chB acquired from the focus evaluation value detection unit 70 to the CPU 90 of the drive unit 16. The CPU 90 of the drive unit 16 determines the focus state of the photographing lens 14 with respect to the image pickup device 52 based on the chA and chB focus evaluation values acquired from the CPU 80 of the focus state detection adapter 30 during AF execution (in AF mode). To detect. The focus state is detected based on the following principle.

  FIG. 5 is a diagram illustrating the relationship between the focus position and the focus evaluation value when a certain subject is photographed, with the horizontal axis indicating the position (focus position) of the focus lens FL of the photographing lens and the vertical axis indicating the focus evaluation value. is there. Curves A and B indicated by solid lines in the figure indicate chA and chB focus evaluation values obtained from the chA and chB video signals, respectively, with respect to the focus position. On the other hand, a curved line C indicated by a dotted line in the figure indicates the focus evaluation value with respect to the focus position when it is assumed that the focus evaluation value is obtained from the video signal obtained from the video image sensor 52.

In the figure, the focus state is in focus when the focus (focus lens FL) is set at the focus position F0 when the focus evaluation value of the image pickup device 52 for video indicated by the curve C is maximized (maximum). Is the case. If the focus of the photographing lens 14 is set to the focus position F1 closer to the focus position F0, the focus evaluation value of chA is the value V _{A1 of the} curve A corresponding to the focus position F1. , ChB focus evaluation value is the value V _{B1 of the} curve B corresponding to the focus position F1. In this case, as can be seen from the figure, the chA focus evaluation value V _A1 is larger than the chB focus evaluation value V _B1 . From this, when the focus evaluation value V _A1 of chA is larger than the focus evaluation value V _{B1 of} chB, the focus is set closer to the in-focus position F0, that is, the front pin It can be seen that

On the other hand, when the focus of the photographic lens 14 is set to the focus position F2 on the infinity side of the focus position F0, the focus evaluation value of chA is the value V _{A2 of the} curve A corresponding to the focus position F2. , ChB focus evaluation value is the value V _{B2 of the} curve B corresponding to the focus position F2. In this case, the chA focus evaluation value V _A2 is smaller than the chB focus evaluation value V _B2 . From this, when the focus evaluation value V _A2 of chA is smaller than the focus evaluation value V _{B2 of} chB, the focus is set to the infinity side from the in-focus position F0, that is, the rear It can be seen that the pin is in a state.

On the other hand, when the focus of the taking lens 14 is set to the focus position F0, that is, the in-focus position, the focus evaluation value of chA becomes the value V _{A0 of the} curve A corresponding to the focus position F0. The focus evaluation value of chB is the value V _{B0 of the} curve B corresponding to the focus position F0. In this case, the chA focus evaluation value V _A0 is equal to the chB focus evaluation value V _B0 . From this, it can be seen that when the chA focus evaluation value V _A0 is equal to the chB focus evaluation value V _B0 , the focus is in the in-focus position F 0, that is, the in-focus state.

  As described above, the focus lens FL of the photographic lens 14 moves back and forth in the optical axis direction in conjunction with the rotation of the focus ring, and is electrically driven by the focus motor 94 of the drive unit 16 shown in FIG. 4 connected to the focus ring. It comes to be driven by. The CPU 90 of the drive unit 16 outputs a drive signal to the focus amplifier 92 to drive the focus motor 94, thereby driving the focus lens FL and acquiring the position of the focus lens FL from the position sensor 96 while focusing. The focus lens FL can be controlled to a desired position by driving the lens FL.

  At the time of AF execution, the CPU 90 detects the current focus state of the photographing lens 14 from the front pin, the rear pin, and the in-focus state based on the chA and chB focus evaluation values as described above. Control FL. Thus, the focus lens FL is set at a position where the focus state is in focus. For example, when the focus state detected from the focus evaluation values of chA and chB is the front focus, the focus lens FL is moved in the infinity direction, and when the focus state is the rear focus, the focus lens FL is moved in the closest direction. . When the focus state is in focus, the focus lens FL is stopped at that position. As a result, the focus lens FL moves to a position where the focus state of the photographic lens 14 is in focus and stops.

  Next, processing related to the CCD block 42 in the main body 40 of the focus state detection adapter 30 will be described. As shown in FIG. 4, information indicated by the CPU 80 is displayed on the display unit 44 also shown in FIG. 1, and the photographing lens in which the focus state detection adapter 30 is mounted on the display unit 44. The type of CCD block 42 that matches the 14 types is displayed.

  The pair of focus state detection CCDs 64A and 64B of the CCD block 42 has a difference in optical path length between the respective image pickup surfaces and, as shown in FIG. 3, a predetermined amount d before and after the image pickup surface of the image pickup device 52. It arrange | positions in the position where an optical path length becomes short, and the position where it becomes long. The graphs A and B of the focus evaluation values of chA and chB as shown in FIG. 5 show that the optical path difference 2d between the focus state detection CCDs 64A and 64B increases as the focal length of the photographing lens 14 increases. The interval between the peak points is appropriate, and the magnitude of the focus evaluation value at the in-focus position F0 where the graphs A and B intersect is appropriate. That is, the focus state can be detected satisfactorily.

  When the focal length of the photographic lens 14 is variable, in order to enable focus detection in the entire variable range, the optical path length difference 2d of the imaging surfaces of the focus state detection CCDs 64A and 64B is set according to the variable range. It is necessary to change. In addition, when the focal length variable range becomes large, it may be difficult to detect the focus state well over the entire range. In such a case as well, the range that makes it possible to detect the focus state well is changed. In addition, it is necessary to change the optical path length difference 2d of the imaging surfaces of the focus state detection CCDs 64A and 64B.

  Therefore, a CCD block in which the imaging surfaces of the focus state detection CCDs 64A and 64B are arranged with an optical path length difference 2d that is most suitable for various commercially available photographic lenses is manufactured and provided to the user. Alternatively, several types of CCD blocks having different optical path length differences 2d on the imaging surfaces of the focus state detection CCDs 64A and 64B are manufactured and provided to the user. Each user owns a CCD block suitable for the type of photographing lens owned in advance, and selects a CCD block suitable for the photographing lens 14 to be actually used with the focus state detection adapter 30 attached. If attached to the main body portion 40 of the detection adapter 30, the optical path length difference 2d of the imaging surfaces of the focus state detection CCDs 64A and 64B can be easily changed to an appropriate size.

  Data indicating which type of CCD block is suitable for the type of photographing lens is tabulated in advance and stored in a memory 82 that can be referred to by the CPU 80 of the main body 40 as shown in FIG.

  FIG. 6 is a flowchart showing the processing procedure of the CPU 80 when displaying the type of the CCD block 42 that matches the type of the photographing lens 14 to which the focus state detection adapter 30 is attached. When the main unit 40 and the drive unit 16 of the focus state detection adapter 30 are communicably connected by the cable 34 as shown in FIG. 1 or when the CCD block 42 is removed from the main unit 40 (described later). The CPU 80 of the main body 40 first obtains information for identifying the type of the photographing lens 14 (name of the photographing lens 14 and the like) from the CPU 90 of the drive unit 16 (which can be detected by the identification sensor 84) (see FIG. Step S10). Then, the type of the CCD block 42 that matches the type of the photographing lens 14 is specified with reference to the table of the memory 82 (step S12). When the type of the suitable CCD block 42 is specified, information indicating the type is displayed on the display unit 44. As a result, the user can easily know the type of the CCD block 42 that matches the type of the photographing lens 14, and by attaching it to the main body 40, the optical path length difference 2d between the imaging surfaces of the focus state detection CCDs 64A and 64B. Can be adapted to the type of photographic lens 14.

  In addition, when the variable range of the focal length of the photographic lens 14 is large and the focus state cannot be satisfactorily detected over the entire range, the focus state is generally satisfactorily detected on the tele side where AF is frequently used. The CCD block that can be displayed may be displayed as suitable, or the variable range of the focal length may be divided into several parts (for example, the tele-side range including the tele end and the wide side including the wide end). Range, or a range between those ranges, etc.), and multiple types of CCD blocks that can detect the focus state well for each range are displayed. May be selected.

  On the other hand, the CPU 80 performs the following processing according to the type of the CCD block 42 actually mounted on the main body 40. As shown in FIG. 4, the main body 40 is provided with an identification sensor 84 that identifies the type of the CCD block 42 attached to the main body 40. For example, if the identification sensor 84 is provided with a predetermined number of terminals and the terminals connected to the specific terminals are different depending on the type of the mounted CCD block 42, the CCD block can be detected by detecting the connected terminals. 42 types can be detected. Whether or not the CCD block 42 is mounted on the main body 40 can also be detected by the identification sensor 84.

  The CPU 80 identifies the type of the CCD block 42 based on a signal from the identification sensor 84 and selects an operation process according to the type. For example, even if a CCD block of a type other than the CCD block displayed on the display unit 44 as being compatible with the type of the photographing lens 14 is mounted on the main body unit 40, it is obtained from the focus evaluation value detection unit 70. In some cases, the focus state can be appropriately detected by performing gain adjustment on the focus evaluation values of chA and chB and supplying them to the CPU 90 of the drive unit 16. In that case, the gain is changed. In addition, when a CCD block that can detect the focus state only in a part of the variable range of the focal length of the photographic lens 14 is mounted, the focus state should be detected well. It is also possible to give a restriction to the CPU 90 of the drive unit 16 so that AF is executed only within the variable range of the focal length that can be performed. Further, it is possible to give an instruction to the CPU 90 of the drive unit 16 to change the focus operation speed during AF according to the type of the mounted CCD block 42.

  FIG. 7 is a flowchart showing a processing procedure for selecting an operation process of the CPU 80. When the main unit 40 and the drive unit 16 of the focus state detection adapter 30 are communicably connected by the cable 34 as shown in FIG. 1 or when the CCD block 42 is mounted on the main unit 40, etc. At a predetermined timing, the CPU 80 identifies the type of the CCD block 42 attached to the main body 40 based on a signal from the identification sensor 84 (step S20). Then, referring to a table created in advance and stored in the memory 82 (step S22), an optimum operation process is selected for the CCD block 42 (step S24). As a result, even if the CCD block 42 mounted on the main body 40 is not the optimum type for the type of the taking lens 14, a certain degree of proper operation can be ensured.

  As described above, in the above-described embodiment, as the focus state detection adapter 30, the half mirror 60 (light splitting optical system) that branches the subject light from the main light path to the focus state detection optical path or the optical system (focus state) of the focus state detection optical path. The case where the detection CCDs 64A and 64B) are made detachable from the photographing lens 14 has been described. However, the present invention is not limited to this, and the half mirror 60 (light splitting optics) that branches subject light from the main line optical path to the focus state detection optical path. System) or a part of the optical system of the focus state detection optical path is integrally formed with the taking lens, the CCD block can be made detachable as in the above embodiment.

  In the above-described embodiment, display is performed so that the type of the CCD block 42 corresponding to the type of the photographing lens 14 can be selected. Display or the like may be performed so that the type of the CCD block 42 corresponding to the variable range of the focal distance that can be performed is selected. In addition, it is not always necessary to display the type of the CCD block 42 to be matched. For example, the type of the CCD block 42 is suitable for which type of photographing lens, or in which range of focal length the focus state can be detected well. You should know in advance whether you can do it.

  In the above-described embodiment, the case where two imaging surfaces having an optical path length difference are arranged in the focus state detection optical path has been described. However, the imaging surface that captures the subject image (video) for focus state detection is in the focus state. The present invention can be applied even when more than two are arranged in the detection optical path.

FIG. 1 is a side view showing an appearance of a television camera system in which a focus state detection adapter to which the present invention is applied is incorporated. FIG. 2 is a diagram showing the configuration of the optical system of the television camera system of FIG. FIG. 3 is a diagram showing the relationship between the optical path lengths of the respective imaging surfaces, with the image pickup device for video of the camera and the CCD for focus state detection of the focus state detection adapter on the same optical axis. FIG. 4 is a block diagram showing a configuration of a control system mainly mounted on the main body of the focus state detection adapter and a configuration of a control system for executing AF mounted on the drive unit 16. FIG. 5 is a diagram illustrating the relationship between the focus position and the focus evaluation value when a certain subject is photographed, with the horizontal axis indicating the position (focus position) of the focus lens FL of the photographing lens and the vertical axis indicating the focus evaluation value. is there. FIG. 6 is a flowchart showing the processing procedure of the CPU of the main body when displaying the type of CCD block that matches the type of the photographing lens to which the adapter for detecting the focus state is attached. FIG. 7 is a flowchart showing a processing procedure for selecting an operation process corresponding to the type of CCD block mounted on the main body of the focus state detection adapter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Camera, 14 ... Shooting lens, 16 ... Drive unit, 30 ... Focus state detection adapter, 40 ... Main body part, 42 ... CCD block, 44 ... Display part, 52 ... Image pick-up element, 60 ... Half mirror, 62 ... Beam splitter, 64A, 64B ... focus state detection CCD, 70 ... focus evaluation value detection unit, 80, 90 ... CPU, 82 ... memory, 84 ... identification sensor, 94 ... focus motor, FL ... focus lens, ZL ... zoom lens

Claims (5)

The subject light that enters the imaging lens and passes through the main optical path and is incident on the imaging surface of the camera image pickup device is divided by the light dividing means, and one of the subject lights obtained by the division is referred to as the main optical path. The light is guided to different focus state detection optical paths, and is incident on a plurality of image pickup surfaces of the focus state detection image pickup elements arranged at positions where the optical path lengths of the focus state detection optical paths are different, and the imaging is performed by each of the plurality of image pickup surfaces. In an imaging device for focus state detection that captures a subject image for detecting the focus state of a lens,
A plurality of the focus state detection image sensors are configured to be detachable from the focus state detection optical path as an integrated block, the focus state detection image sensors constituting a plurality of image pickup planes arranged in the focus state detection optical path. An image pickup apparatus for detecting a focus state, wherein the block configured to have a desired optical path length difference can be mounted on the focus state detection optical path.   The plurality of image pickup surfaces of the focus state detection image pickup device are image pickup surfaces of different image pickup devices, on an optical path through which each subject light divided by the light dividing means arranged in the focus state detection optical path passes. The imaging device for focus state detection according to claim 1, wherein   3. The focus state detection imaging apparatus according to claim 2, wherein the block includes the focus state detection image pickup device and a light splitting unit disposed in the focus state detection optical path.   The focus state according to claim 1, 2, or 3, wherein the light dividing means arranged in the main line optical path is arranged in an adapter that is detachably mounted between the photographing lens and the camera. Imaging device for detection.   5. The focus state detection according to claim 4, wherein the adapter includes detection means for detecting the type of the photographic lens mounted and display means for displaying the block type that matches the detected type. Imaging device.

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