JP2008058819A - Lens device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens device which is capable of reducing operation noise when a lens is moved and the exposure of a moving part. <P>SOLUTION: The lens device 10 is equipped with: a fixed lens barrel 60 having an opening 76 in the side surface thereof; lens frames 62b and 62c which are provided in the fixed lens barrel 60 and supported so as to be freely moved in the direction of an optical axis O; a cam barrel 64 which is provided in the fixed lens barrel 60 and turned to move the lens frames 62b and 62c in the direction of the optical axis O; a pulley 74 which is provided outside the fixed lens barrel 60 and for turning the barrel body 64; an endless belt 72 which passes through an opening 76, to connect the cam barrel 64 and the pulley 74; and tension adjusting rollers 79 and 79 for adjusting the tension of the endless belt 72. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens device, and more particularly to a lens device mounted on a camera body of a television camera.

In a lens device for a television camera, a moving lens such as a focus lens is supported so as to be movable in the optical axis direction and is moved by driving a motor or the like. The motor is disposed outside the fixed lens barrel and is connected to the moving lens via a helicoid or a feed screw mechanism. For example, in the lens apparatus of Patent Document 1, a focus lens moving frame and a motor are connected via a feed screw mechanism, and the focus lens is moved in the optical axis direction by driving the motor. In the lens device of Patent Document 2, the focus lens moving frame and the drive source are connected via a helicoid.
JP 2001-242370 A Japanese Patent Laid-Open No. 11-125763

  However, since the conventional lens device moves the lens frame via a feed screw mechanism or a helicoid, there is a problem that the operating noise is large when the lens frame is moved. In particular, the television lens device has a problem in that since the focus lens is large, the load applied to the helicoid and the feed screw is large and the operation noise is large.

  Therefore, it is conceivable to move the lens frame using a cam mechanism. However, in this case, since the cam cylinder is disposed outside the fixed barrel, the exposure of the movable part becomes large, and a large cover must be attached to the fixed barrel to cover this exposure. There was a problem.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lens device that can reduce the operating sound when moving the lens and can reduce the exposure of the movable portion. .

  In order to achieve the above object, the invention according to claim 1 is a fixed lens barrel having an opening on a side surface, a lens frame provided inside the fixed lens barrel and supported so as to be movable in the optical axis direction, A cam barrel that is provided inside the fixed lens barrel and is rotatably supported, is connected to the lens frame via a cam mechanism, and rotates to move the lens frame in the optical axis direction; A rotation driving means that is provided outside the fixed lens barrel and rotates the cam cylinder; an endless belt that connects the cam cylinder and the rotation driving means through an opening of the fixed lens barrel; And a tension adjusting roller that adjusts the tension of the belt by being engaged with the belt.

  According to the first aspect of the present invention, since the cam cylinder is driven by the belt, the operation noise can be reduced as compared with the case where a feed screw mechanism or a helicoid is used.

  According to the first aspect of the present invention, the cam barrel is disposed inside the fixed barrel, and an opening is formed in the side of the fixed barrel so that the cam barrel and the rotation driving means are connected by the belt. As a result, exposure of the movable part can be minimized.

  According to a second aspect of the present invention, in the first aspect of the invention, the fixed lens barrel includes a cover that covers an opening of the fixed lens barrel and a belt drawn from the opening to the outside of the fixed lens barrel. A fixed lens barrel is detachably provided. According to invention of Claim 2, by attaching a cover, the exposed part of a movable part can be covered and the malfunctioning by dust etc. can be prevented reliably. Further, according to the present invention, since the exposed part of the movable part is small, the cover can be made small.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the cam cylinder includes a ring-shaped bearing disposed between the outer peripheral surface of the cam cylinder and the inner peripheral surface of the fixed barrel. It is characterized by being supported.

  According to the present invention, the cam cylinder is disposed inside the fixed barrel, and an opening is formed in the side surface of the fixed barrel so that the cam cylinder and the rotation driving means are connected by the belt. Exposure can be minimized and the operating noise can be reduced.

  Preferred embodiments of a lens apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a photographing optical system of a television lens apparatus to which a lens apparatus according to the present invention is applied. A television lens device 10 shown in the figure is used by being mounted on a camera body 12 of a television camera for broadcasting or business use.

  As shown in FIG. 1, a half mirror 14 is disposed in the photographing optical system of the TV lens device 10, and a normal main line along an optical axis O that guides subject light to the camera body 12 by the half mirror 14. The optical path for AF along the optical axis O ′ is branched from the optical path. That is, the photographing optical system includes a main optical path along the optical axis O that guides subject light to the camera body, and the AF optical path along the optical axis O ′ branched from the optical path of the optical axis O. .

  On the main optical path, the focus lens (group) FL, zoom lens (group) ZL, aperture I, front relay lens (group) RA, half mirror 14, rear relay lens (group) RB are sequentially arranged from the front side (subject side). Is arranged.

  The focus lens (group) FL is composed of a plurality of lens groups as will be described later, and the focal position (the position where the focus is achieved) changes by moving some of the lens groups in the direction of the optical axis O. The zoom lens ZL is supported so as to be movable in the direction of the optical axis O, and the zoom magnification (focal length) changes as the zoom lens ZL moves back and forth in the direction of the optical axis O. The diaphragm I is configured to open and close. When the position (aperture) of the diaphragm I changes, the amount of subject light passing through the photographing optical system changes.

  Subject light incident on the photographing lens from the subject passes through the focus lens FL, zoom lens ZL, aperture I, front relay lens RA, half mirror 14 and rear relay lens RB in order, and the optical system in the camera body 12. Is incident on. The optical system of the camera body 12 includes a color separation optical system 30 that separates incident subject light into wavelengths of three colors of red (R), green (G), and blue (B), and subjects of each color separated. Video CCDs for each of R, G, and B for picking up an image of light are arranged. Incidentally, R, G, and B image CCDs arranged at optically equivalent optical path length positions are represented by one image CCD 32 as shown in FIG. The subject light incident on the imaging surface of the video CCD 32 is photoelectrically converted by the video CCD 32. Then, a video signal for recording or reproduction is generated by a predetermined signal processing circuit in the camera body 12.

  On the other hand, the AF optical path includes an AF relay lens RB ′ equivalent to the rear relay lens RB, a mirror 18, a light splitting optical system 20 including two prisms 20A and 20B, and the AF CCD 16A, 16B is arranged. In the half mirror 14, the subject light incident through the front relay lens RA is divided into two. Of the incident subject light, the subject light transmitted through the half mirror 14 is guided to the camera body 12 along the main optical path of the optical axis O as described above. The subject light reflected by the half mirror 14 is guided to an AF optical path having an optical axis O ′ substantially perpendicular to the optical axis O. For example, about 50% of the subject light is transmitted through the half mirror 14 with respect to the subject light incident on the half mirror 14. However, as the half mirror 14, one having arbitrary transmittance and reflectance characteristics can be used.

  The subject light reflected by the half mirror 14 and guided to the AF optical path passes through the AF relay lens RB ′ and then totally reflected by the mirror 18 and enters the light splitting optical system 20. The subject light incident on the light splitting optical system 20 is split into two subject lights having equivalent amounts of light at the half mirror surface M where the first prism 20A and the second prism 20B are joined. The subject light reflected by the half mirror surface M enters the imaging surface of one AF CCD 16A, and the subject light transmitted through the half mirror surface M enters the imaging surface of the other AF CCD 16B.

  Video signals obtained by the AF CCDs 16A and 16B are used in an optical path length difference type AF.

  Further, the AF relay lens RB ′ is movable in the direction of the optical axis O ′ and is driven by a motor (not shown) installed on the lens barrel. When the position of the AF relay lens RB ′ changes, the position at which the subject light branched into the AF optical path changes, and the relative position between the position at which the subject light forms an image and the imaging surface of the AF CCD is changed. The positional relationship changes. As a result, an effect equivalent to that obtained when the position where the imaging surfaces of the AF CCDs 16A and 16B are arranged is changed.

  In the AF control, a part of the lens group of the focus lens FL is controlled to move in the optical axis O direction based on the video signals obtained by the AF CCDs 16A and 16B. The AF control will be described in detail later.

  Next, the drive mechanism of the focus lens FL will be described with reference to FIGS. 2 is a cross-sectional view of the lens device 10, FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2, and FIG. 4 is an exploded perspective view. 2 shows a cross section at the position of line 2-2 in FIG.

  As shown in FIG. 2, the focus lens FL includes three lens groups FLa, FLb, and FLc. The lens groups FLa, FLb, and FLc are supported by lens frames 62a, 62b, and 62c, respectively, and the lens frame 62a is fixed to a fixed barrel (main body) 60.

  The fixed barrel 60 includes an outer cylinder part 60X having a large diameter and an inner cylinder part 60Y having a small diameter, and a lens frame 62a is fixed to the tip of the outer cylinder part 60X. Further, a cam cylinder 64 is provided between the outer cylinder part 60X and the inner cylinder part 60Y, and the cam cylinder 64 is rotatable to the outer cylinder part 60X via ring-shaped bearings 68 and 68. Supported by

  As shown in FIG. 3, four cam grooves 66b, 66b, 66c, 66c are formed on the inner peripheral surface of the cam cylinder 64, and cam pins 90b, 90c described later are engaged with the cam grooves 66b, 66c. Is done.

  As shown in FIG. 4, a gear 70 is formed on the outer peripheral surface of the base end side of the cam cylinder 64. An endless belt 72 shown in FIGS. 5 and 6 is engaged with the gear 70. The endless belt 72 is drawn to the outside of the fixed barrel 60 from an opening 76 formed in the outer cylindrical portion 60 </ b> X of the fixed barrel 60 and is wound around the pulley 74. The pulley 74 is rotatably supported by a main body 78 connected to the fixed lens barrel 60, and is connected to a rotation shaft of a motor (not shown). Therefore, driving the motor causes the pulley 74 to rotate and the endless belt 72 to rotate, so that the cam cylinder 64 can be rotated.

  Further, tension adjusting rollers 79 and 79 are engaged with the endless belt 72. The tension adjusting rollers 79 and 79 are disposed outside the fixed lens barrel 60, are attached to the main body 78, and are rotatably supported. Further, the tension adjusting rollers 79 and 79 can be adjusted in position in the direction of the arrow in FIG. 6, and the tension of the endless belt 72 is adjusted by adjusting the positions of the tension adjusting rollers 79 and 79. Accordingly, the endless belt 72 can be wound around the cam cylinder 64 and the gear 70 with a predetermined tension, and the rotational driving force of the motor can be reliably transmitted to the cam cylinder 64.

  A cover 77 is detachably attached to the opening 76 of the fixed lens barrel 60. By attaching the cover 77, the pulley 74, the tension adjusting rollers 79 and 79, and a part of the endless belt 72 are accommodated in the cover 77. Thereby, since the exposure of the movable part is eliminated, it is possible to reliably prevent dust and the like from adhering to the movable part and causing malfunction.

  As shown in FIG. 2, a lens frame 62b that holds the focus lens FLb and a lens frame 62c that holds the focus lens FLc are disposed inside the inner cylindrical portion 60Y of the fixed barrel 60.

  As shown in FIGS. 3 and 4, four guide members 80b, 80b,... Are integrally formed with the lens frame 62b on the outer peripheral surface of the lens frame 62b. The guide members 80b are arranged at equal intervals (90 ° intervals) in the circumferential direction. The guide member 80b protrudes from the outer peripheral surface of the lens frame 62b and extends toward the lens frame 62c in the optical axis O direction. A rectilinear groove 82b is formed in the optical axis O direction on the outer surface of the guide member 80b, and guide pins 84b and 86b are engaged with the rectilinear groove 82b.

  The guide pins 84b and 86b are provided on the inner peripheral surface of the inner cylindrical portion 60Y of the fixed barrel 60. Further, as shown in FIG. 7, rollers 85b and 87b are rotatably supported at the tips of the guide pins 84b and 86b, and are engaged with the rectilinear grooves 82b via the rollers 85b and 87b. Two guide pins 84b and two guide pins 86b are engaged with one rectilinear groove 82b. Among these, the guide pin 86b is provided such that the rotation shaft p1 of the roller 87b and the mounting shaft p2 to the fixed barrel 60 are eccentric. Therefore, when the guide pin 86b is attached to the fixed lens barrel 60, the position of the roller 87b can be adjusted by rotating the guide pin 86b about the attachment shaft p2, and the roller 87 is reliably engaged with the side surface of the rectilinear groove 82b. Can be made.

  As described above, the guide member 80b having the rectilinear groove 82b is provided in the lens frame 62b, and the guide pins 84b and 86b to be engaged with the rectilinear groove 82b are provided in the fixed barrel 60. Therefore, the lens frame 62b is provided in the fixed barrel 60. On the other hand, it is supported so as to be movable in the direction of the optical axis O.

  As shown in FIG. 3, two cam pins 90b project from the outer peripheral surface of the lens frame 62b. Each cam pin 90b is disposed at a position different from the guide member 80b in the circumferential direction, and is disposed at the end of the lens frame 62b on the lens frame 62c side in the optical axis O direction. The cam pin 90 b is disposed through the opening 94 b in the optical axis O direction of the fixed barrel 60 and is engaged with the cam groove 66 b of the cam barrel 64. Therefore, by rotating the cam cylinder 64, the cam pin 90b moves in the direction of the optical axis O, and the lens frame 62b moves back and forth in the direction of the optical axis O. The opening 94b of the fixed lens barrel 60 is formed with a width larger than the diameter of the cam pin 90b, and the cam pin 90b is arranged without contacting the fixed lens barrel 60.

  On the other hand, the outer diameter of the lens frame 62c is smaller than the inner diameter of the lens frame 62b, and the lens frame 62c can be nested and combined inside the lens frame 62b. Like the lens frame 62b, the lens frame 62c is provided with four guide members 80c, 80c,. The guide members 80c are arranged at equal intervals (90 ° intervals) in the circumferential direction, and are formed integrally with the lens frame 62c. The guide member 80c protrudes from the outer peripheral surface of the lens frame 62c and extends toward the lens frame 62b in the optical axis O direction. When the lens frame 62b and the lens frame 62c are combined in a nested manner, the guide member 80c is disposed outside the lens frame 62b and between the guide members 80b and 80b, as shown in FIG. . That is, when the lens frame 62b and the lens frame 62c are combined in a nested manner, the guide members 80b and the guide members 80c are alternately arranged in the circumferential direction.

  As shown in FIGS. 3 and 4, a rectilinear groove 82c is formed in the optical axis O direction on the outer surface of the guide member 80c, and guide pins 84c and 86c are engaged with the rectilinear groove 82c. The guide pins 84c and 86c are provided on the inner peripheral surface of the inner cylinder part 60Y of the fixed barrel 60. Similarly to the guide pins 84b and 86b, the guide pins 84c and 86c have a roller (not shown) rotatably supported at their tips, and are engaged with the rectilinear groove 82c via the rollers. Two guide pins 84c and two guide pins 86c are arranged to engage with one rectilinear groove 82c. Among these, the guide pin 86c, like the guide pin 86b, is provided with an eccentric rotation shaft and mounting shaft of the roller so that the position of the roller can be freely adjusted.

  As described above, the guide member 80c having the rectilinear groove 82c is provided in the lens frame 62c, and the guide pins 84c and 86c that engage with the rectilinear groove 82c are provided in the fixed barrel 60. Thus, it is supported so as to be movable in the direction of the optical axis O.

  A cam pin 90c projects from the outer peripheral surface of the lens frame 62c. The cam pin 90c is disposed at a position different from the guide member 80c in the circumferential direction, and is disposed at the end of the lens frame 62c on the lens frame 62b side in the optical axis direction. The cam pin 90c is located at a position different from the cam pin 90b of the lens frame 62b in the circumferential direction and in the optical axis O direction when the lens frame 62b and the lens frame 62c are assembled in a nested manner and assembled to the fixed barrel 60. Are arranged at substantially the same position. A notch groove 63b is formed at the position of the cam pin 90c at the end of the lens frame 62b on the lens frame 62c side, and the cam pin 90c enters the notch groove 63b in a non-contact manner. And the cam pin 90c are arranged at substantially the same position in the optical axis O direction.

  The cam pin 90 c is disposed so as to pass through the opening 94 c in the optical axis O direction formed in the inner cylinder portion 60 </ b> Y of the fixed barrel 60, and is engaged with the cam groove 66 c of the cam cylinder 64. Therefore, by rotating the cam cylinder 64, the cam pin 90c moves in the direction of the optical axis O, and the lens frame 62c moves back and forth in the direction of the optical axis O. The opening 94c of the fixed barrel 60 is formed with a width larger than the diameter of the cam pin 92c, and the cam pin 90c is arranged without contacting the fixed barrel 60.

  In the cam cylinder 64, the cam groove 66b and the cam groove 66c are formed in different shapes, and the movement lens frame 62b and the movement lens frame 62c have different movement patterns (that is, different movement speeds, movement amounts, or different. (Timing).

  According to the lens device 10 configured as described above, the cam barrel 64 is disposed inside the fixed barrel 60 (specifically, the outer barrel portion 60X), and the opening 76 is formed on the side surface of the fixed barrel 60. The endless belt 72 is wound around the cam cylinder 64 and the pulley 74 through the opening 76. Therefore, there is very little exposure of the movable part when rotating the cam cylinder 64. Furthermore, according to the present embodiment, the cover 77 is attached to the exposed part of the movable part, and the movable part is reliably covered by the cover 77 and the fixed lens barrel 60. Thereby, the malfunctioning by dust etc. can be prevented reliably.

  Further, according to the present embodiment, since the cam cylinder 64 is rotated by the endless belt 72, the operating noise can be made smaller than when a feed screw mechanism or a helicoid is used.

  Furthermore, according to the present embodiment, the tension adjusting rollers 79 and 79 are provided so that the tension of the endless belt 72 can be adjusted. Therefore, the endless belt 72 can be easily attached and the endless belt 72 can be easily mounted. The belt 72 can be reliably wound around the cam cylinder 64 and the pulley 74.

  Next, AF control in the present embodiment will be described.

  FIG. 9 is a configuration diagram showing a configuration of a control system related to AF control using the lens lens apparatus 10. The control system components are mounted on a drive unit (not shown) mounted mainly on the side of the lens barrel.

  The control system related to AF control controls the focus lens FL (specifically, the above FLb and FLc) and the AF relay lens RB ′. The CPU 40 controls the entire system as a whole, the focus lens FL, Obtained from motors FM, RM and position sensors FP, RP connected to each of the AF relay lenses RB ′, amplifiers FD, RD connected to the motors FM, RM, and the pair of AF CCDs 14A, 14B. It is composed of an AF circuit 50 that acquires information necessary for AF control based on a video signal.

  When a drive signal having a predetermined value is output from the CPU 40 to each amplifier FD, RD, each motor FM, RM rotates at a speed corresponding to the value of the drive signal, and the rotation speed of each motor FM, RM is set. The focus lens FL and the AF relay lens RB ′ move at a corresponding speed. Further, position signals indicating the current positions of the focus lens FL and the AF relay lens RB ′ are given to the CPU 40 from the position sensors FP and RP. Thereby, the CPU 40 can control the focus lens FL and the relay lens RB ′ so as to have a desired moving speed or a desired position.

  At the time of AF control, the CPU 40 controls the focus lens FL based on the AF information obtained from the AF circuit 50 so that a predetermined subject is in focus in the video imaged by the video CCD 32 of the camera body 12. .

  Here, basic control contents of AF control in the present autofocus system will be described. FIG. 10 shows the image CCD 32 of the camera body 12 and the pair of AF CCDs 16A and 16B on the same optical axis. As shown in the figure, the optical path length of the subject light incident on the imaging surface of one AF CCD 16A is set shorter than the optical path length of the subject light incident on the imaging surface of the other AF CCD 16B. The optical path length of subject light incident on the imaging surface of the image CCD 32 is set to be an intermediate length. In other words, the image pickup surfaces of the pair of AF CCDs 16A and 16B are arranged so as to be positioned at an equal distance d in the front-rear direction with respect to the image pickup surface of the image CCD 32. As will be described later, the positional relationship between the imaging surface of the image CCD 32 and the imaging surfaces of the AF CCDs 16A and 16B changes as the position of the AF relay lens RB ′ moves. The position of the AF relay lens RB ′ at this time is set as a reference position.

  According to the pair of AF CCDs 16A and 16B arranged in the lens device 10 in this way, the imaging surfaces of the subject light incident on the lens device 10 are placed at equidistant positions before and after the imaging surface of the imaging CCD 32, respectively. A video signal equivalent to the arrangement is obtained. The AF CCDs 16A and 16B do not need to capture color images, and in the present embodiment, it is assumed that black and white video signals (luminance signals) are acquired from the AF CCDs 16A and 16B.

  In the AF circuit 50 of FIG. 9, the video signals obtained by the AF CCDs 16A and 16B are converted into digital signals by the A / D converter 52, and then input to the high-pass filter (HPF) 54. Only the signal of the frequency component is extracted. The video signal from which the signal of only the high frequency component is extracted is subsequently input to the gate circuit 56, and the gate circuit 56 sets a predetermined AF area (for example, a rectangular area at the center of the screen) set within the photographing range (screen). ) Is extracted within the range corresponding to.

  The range of the AF area is set by an instruction signal from the CPU 40, and the operator can specify a desired range using a predetermined controller.

  The video signal extracted by the gate circuit 56 is integrated for each field by the addition circuit 58A when it is obtained from the AF CCD 16A, and by the addition circuit 58B when it is obtained from the AF CCD 16B. It is output from the AF circuit 50 for each field.

  The integrated values obtained from the adder circuits 58A and 58B in this way indicate values for evaluating the contrast height of the subject images captured by the AF CCDs 16A and 16B, respectively. In this specification, this integrated value is referred to as a focus evaluation value. The focus evaluation value obtained from the video signal of the AF CCD 16A is referred to as the chA focus evaluation value, and the focus evaluation value obtained from the AF CCD 16B video signal is referred to as the chB focus evaluation value.

  The CPU 40 detects the focus state of the imaging optical system with respect to the image CCD 32 based on the chA and chB focus evaluation values obtained in this way. The focus state is detected based on the following principle. FIG. 11 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 60 and the vertical axis indicating the focus evaluation value. It is. Curves A and B indicated by solid lines in the figure indicate the focus evaluation values of chA and chB obtained from the AF CCDs 16A and 16B, 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 CCD 32.

  In the figure, the focus state is in focus when the focus is set at the focus position F0 when the focus evaluation value of the image CCD 32 indicated by the curve C is maximized (maximum). If the focus of the photographing optical system is set to the focus position F1 closer to the focus position F0, the focus evaluation value of chA becomes the value VA1 of the curve A corresponding to the focus position F1, The focus evaluation value of chB is the value VB1 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 VA1 is larger than the chB focus evaluation value VB1. From this, when the focus evaluation value VA1 of chA is larger than the focus evaluation value VB1 of chB, the focus is set closer to the focus position F0, that is, the state of the front pin It turns out that it is.

  On the other hand, when the photographing optical system 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 VA2 of the curve A corresponding to the focus position F2, The focus evaluation value of chB is the value VB2 of the curve B corresponding to the focus position F2. In this case, the chA focus evaluation value VA2 is smaller than the chB focus evaluation value VB2. From this, when the focus evaluation value VA2 for chA is smaller than the focus evaluation value VB2 for chB, the focus is set to the infinity side from the focus position F0, that is, the rear pin It turns out that it is in a state.

  On the other hand, when the focus of the photographing optical system is set to the focus position F0, that is, the focus position, the focus evaluation value of chA is the value VA0 of the curve A corresponding to the focus position F0, and chB Is the value VB0 of the curve B corresponding to the focus position F0. In this case, the chA focus evaluation value VA0 is equal to the chB focus evaluation value VB0. From this, it can be seen that when the focus evaluation value VA0 for chA and the focus evaluation value VB0 for chB are equal, the focus is set at the focus position F0, that is, the focus state.

  In this way, it is possible to detect whether the current focus state of the imaging optical system is the front pin, the rear pin, or the in-focus state with respect to the image CCD 32 based on the focus evaluation values of chA and chB.

  In the AF control, the CPU 40 in FIG. 9 performs focus so as to achieve the in-focus state while sequentially detecting the focus state of the photographing optical system with respect to the image CCD 32 based on the chA and chB focus evaluation values as described above. The lens FL is controlled. For example, when the focus state is the front pin, the focus lens FL is moved in the infinity direction, and when the focus state is the rear pin, the focus lens FL is moved in the closest direction. When the focus state is in focus, the focus lens FL is stopped. As a result, the focus lens FL moves to a position where the focus state of the photographing lens is in focus and stops. An AF method in which automatic focus adjustment is performed using a plurality of AF CCDs having optical path length differences is referred to as an optical path length difference method.

Schematic diagram showing a photographing optical system of a television lens apparatus employing the lens apparatus according to the present invention. Cross-sectional view of a TV lens device showing a focus lens drive mechanism Sectional view along line 3-3 in FIG. 2 is an exploded perspective view of the focus lens driving mechanism of FIG. The perspective view which shows the drive mechanism of a cam cylinder Sectional view along line 6-6 in FIG. A perspective view showing a guide member and a guide pin The perspective view which shows the state which combined the lens frame Configuration diagram showing the configuration of a control system related to AF control The figure which represents on the same optical axis the image CCD of the camera body and the pair of AF CCDs Explanatory diagram used to explain focus state detection principle

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Lens apparatus, 12 ... Camera body, 60 ... Fixed lens barrel, 60X ... Outer cylinder part, 60Y ... Inner cylinder part, 62a-62c ... Lens frame, 64 ... Cam cylinder, 66b, 66c ... Cam groove, 70 ... Gear 72 ... Endless belt, 74 ... Pulley, 76 ... Opening, 77 ... Cover, 78 ... Main body, 80b, 80c ... Guide member, 82b, 82c ... Straight groove, 84b, 84c, 86b, 86c ... Guide pin, 90b, 90c ... Cam pin

Claims (3)

A fixed barrel having an opening on the side;
A lens frame provided inside the fixed lens barrel and supported so as to be movable in the optical axis direction;
A cam barrel that is provided inside the fixed lens barrel and is rotatably supported, is connected to the lens frame via a cam mechanism, and rotates to move the lens frame in the optical axis direction;
A rotation driving means provided on the outer side of the fixed barrel for rotating the cam barrel;
An endless belt connecting the cam cylinder and the rotation driving means through the opening of the fixed barrel;
And a tension adjusting roller that adjusts the tension of the belt by being engaged with the belt.   The fixed lens barrel is provided with a cover that covers the opening of the fixed lens barrel and a belt drawn from the opening to the outside of the fixed lens barrel so as to be detachable from the fixed lens barrel. The lens device according to claim 1.   The said cam cylinder is supported via the ring-shaped bearing arrange | positioned between the outer peripheral surface of this cam cylinder, and the internal peripheral surface of the said fixed barrel. Lens device.

Images