JPH0769511B2 - Camera with zoom lens - Google Patents

Description

The present invention relates to a camera, such as a video camera, equipped with a zoom lens having a so-called subject tracking device for knowing the subject position within a screen.

Conventionally, some so-called automatic tracking methods have been proposed in which an object existing on the screen of a device such as a camera is used as a subject and the position of the object is always grasped even when the position is changed on the screen. . As means for extracting the feature of an object, a method of recognizing a shape, a method of using a characteristic contrast in the object, and a method of using color are disclosed.

A camera for capturing a moving image, such as a video camera, is assumed here to use these automatic tracking. That is, in a conventional video camera with an automatic focusing device, when a type without a parallax is used for the distance measuring field of the automatic focusing device, the distance from the center of the screen is always measured. Due to the configuration, there was a drawback that the subject to be focused must always be placed in the center of the screen. Therefore, although technologies for changing the distance measuring visual field device are also disclosed, these methods allow the distance measuring visual field position to be changed by the photographer's operation of a knob or the like, and the subject moves during the photographing. In this case, it is difficult to always maintain the distance measuring position on the subject due to these knobs.

On the other hand, among various methods already used in cameras as a distance measuring device, a method using a peak of a high frequency component of a luminance signal is known particularly in a video camera. In the video camera, however, the above-mentioned subject tracking method was introduced,
It is conceivable to perform automatic focusing from a luminance signal at a position corresponding to the position of the object being tracked. With the camera configured as described above, it is possible to obtain an image in which the subject existing in the screen is always in focus regardless of the position thereof.

By the way, in the video camera configured as described above, as far as the subject is present in the screen as described above, the operability is remarkably improved as compared with the conventional video camera. There was a problem with the operation when it came out.

An object of the present invention is to solve the above-mentioned drawbacks of the conventional example and to keep the subject in the screen for a long time, thereby enabling operations such as panning and tilting, and as a result, the tracking device loses sight of the subject. It is to provide a camera with a zoom lens with a low probability, the gist of which is
An image sensor that receives an image formed by the zoom lens, a tracking gate determination unit that determines a tracking gate according to the subject, and a subject detection unit that causes the tracking gate to follow the subject based on the output signal of the image sensor,
A discriminating unit that discriminates the in-focus state based on the output signal of the image sensor in the tracking gate, a focusing unit that performs focusing adjustment by the zoom lens based on the output of the discriminating unit, and a limit area in the photographing screen. Area setting means for setting, detection means for detecting that the tracking gate has reached the limit area, and magnification changing means for changing the focal length of the zoom lens to the short focus side by the output of the detection means. It is characterized by having done.

The present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 shows a shooting screen of a video camera device. When shooting a subject S moving to the left with the camera fixed, (a) → (b) →
It is schematically shown in the order of (c). In addition, 1 is a photographing screen frame, 2 is a limit area, and the present invention performs some operation when the subject S goes out or is going to go outside the limit area 2.

As described above, the gist of the present invention is to keep the subject in the screen for as long as possible, and
When the subject S moves to the position, the focus distance is changed to the wide angle side to widen the angle of view. As shown in FIG. 1 (a), when the subject S reaches the position of the limit area 2 while photographing the subject S moving leftward on the relatively telephoto side, FIG.
By changing the focal length to a wide angle as shown in (c), the subject S is grasped near the end of the limit area 2.

FIG. 2 shows an auto-zoom circuit of a zoom lens for driving a variable power lens group according to the present invention. This circuit includes a power zoom switch 4 and a power zoom switch 4.
Changeover switches 5 and 6, a zoom motor drive circuit 7, a power zoom motor 8, a control signal input terminal 9, a changeover switch 10, a power supply circuit 11 having a variable resistance for changing the power zoom speed, and an operation according to the present invention. It is composed of a power supply circuit 12 used at the time.

In normal operation, as shown in FIG. 2, the changeover switch 5 is in a state in which the contacts 5a and 5c are closed, the changeover switch 6 is in a state in which the contacts 6a and 6c are closed, and the changeover switch 10 is in a state in which the contacts 10a and 10b are closed. In this state, when the power zoom switch 4 composed of an external seesaw switch closes the contacts 4a and 4b, the power zoom motor 8 rotates in the direction in which the focal length of the zoom lens becomes longer, that is, the telephoto direction, On the contrary
When the sides of 4a and 4c are closed, they rotate in a direction in which the focal length is short, that is, the wide angle. The rotation of the power zoom motor 8 is adapted to change the zoom lens system and the correction system lens of the zoom lens by a predetermined amount by a conventionally known method.

Here, there is a defined relationship between the limit area position and the tracking gate for grasping the subject S, and when a command to change the focal length to the wide angle side comes, the changeover switch 5 makes contact 5a.
And 5b, the contacts 6a and 6b of the changeover switch 6 and the contacts 10a and 10c of the changeover switch 10 are closed. As a result, when the control signal is transmitted from the input end 9, the speed determined by the power zoom switch 4 and the power supply circuit 11 is ignored, and the constant speed determined by the power supply circuit 12, that is, the rotation speed of the zoom operation ring is changed. The focal length changes to the wide-angle side.

FIG. 3 is a block circuit configuration diagram showing an embodiment of the present invention. Reference numerals 13 to 15 show optical elements constituting a zoom lens for photographing, and 13 is a so-called front portion of the zoom lens which is involved in focus adjustment. A ball lens group, 14 is a lens group for varying the focal length, and is actually composed of two groups, a variable power system and a correction system, and 15 is an image forming system lens group. A CCD image sensor 16 which is a solid-state image pickup device is arranged behind these lens groups 13 to 15.

The image sensor 16 is driven by a CCD drive circuit 17, and its output is passed through a signal processing circuit 18 to a first gate circuit.
It is divided into an output to 19 and an NTSC / TV signal for video. The output of the first gate circuit 19 is further connected to a second gate circuit 20 and a color detection circuit 21, respectively, and the output of the second gate circuit 20 is passed through a focusing circuit 22 and a focusing motor drive circuit 23. A focusing motor 24 that moves the ball lens group 13 forward and backward is driven.

On the other hand, the output of the color detection circuit 21 is connected to the subject position detection circuit 25, and the outputs thereof are connected to the warning circuit 26 and the tracking gate position determination circuit 27, respectively. Also, front lens group 13
The movement information of the warning circuit 26, the tracking gate size determination circuit 28
Respectively connected to. Tracking gate size determination circuit
The output of 28 is connected to the tracking gate position determining circuit 27, and the output of this tracking gate position determining circuit 27 is the first gate circuit 1
9, output to the second gate circuit 20 and the comparison circuit 29, respectively. The output of the limit area setting circuit 30 is connected to the comparison circuit 29, and the output of the comparison circuit 29 drives the power zoom motor 8 for driving the variable focus lens group 14 via the zoom motor drive circuit 7. There is. Further, the output of the color designation circuit 31 is input to the subject position detection circuit 24, and the output of the clock circuit 32 is connected to the CCD drive circuit 17 and the first gate circuit 19, respectively.

Next, this operation will be described.
An image is stored on the CCD image sensor 16 by 13 to 15. The image sensor 16 outputs a video signal that constitutes one field in 1/60 seconds based on the signals of the clock circuit 32 and the CCD drive circuit 17. This signal is a signal processing circuit
After being subjected to a lot of known arithmetic processing by 18, the signal is output as an NTSC / TV signal, for example.

On the other hand, the current position of the front lens group 13, that is, the focusing distance,
Two pieces of information on the current focal length by the variable focus lens group 14 are transmitted to the tracking gate size determination circuit 28, and the optimum size of the tracking gate is determined. The determined size information of the tracking gate is transmitted to the tracking gate position determining circuit 27, and the subject S is tracked based on, for example, the unique color of the subject S. That is, the color information in or around the tracking gate is extracted as a color from the video signal extracted by the first gate circuit 19 via the color detection circuit 21, and is tracked by the subject position detection circuit 25. At this time, a procedure for remembering the subject S at the beginning of shooting is naturally required, but the color designating circuit 31 is used at that time. That is, to summarize the operations related to tracking, the video signal existing in or around the tracking gate is extracted from the video signal, and if it is determined that the designated color is moving compared to the previous time, the tracking gate is moved in that direction To let it.

Here, although detailed description regarding the algorithm of the arithmetic processing is omitted, it is preferable that the arithmetic speed is high. At least
Tracking becomes difficult if there is a movement that exceeds the back projection distance of the size of the tracking gate to the object side during 1/60 seconds.
Further, in the case of this embodiment, the luminance signal for automatic focusing is further extracted by the second gate circuit 20 from the area taken out by the tracking gate, and the high frequency of the Y signal in this distance measuring field of view is obtained. The components are calculated by the focusing circuit 22 to determine the front focus, the rear focus, etc., and the focus motor 24 is driven.

The warning circuit 26 keeps track of the tracking gate and the limit area setting circuit 30 when the subject S is lost in the subject position detection circuit 25 or when the forced zooming to the wide angle end at the wide angle end.
Is operated in a predetermined positional relationship,
As a method, for example, it is possible to display with an LED inside the finder.

In order for the subject S to approach the limit area 2 and serve as a trigger for changing the focal length of the zoom lens to the wide angle side, the boundary line of the limit area 2 set by the limit area setting circuit 30 and the boundary line of the tracking gate match, for example. Several judgment methods such as time can be considered. In any case, this predetermined condition is judged by the comparison circuit 29. For example, in this example, when the boundary line of the limit area 2 and the boundary line defining the tracking gate match, the zoom motor drive circuit Output is issued to 7.

In the embodiment shown in FIG. 3 of the present invention, the color detecting means is used as the tracking means, but other methods for specifying the subject S will not cause any problems. Regarding the limit area 2, in addition to the case where the limit area 2 is set inside the photographing screen frame 1 as shown in FIG. 1, the photographing screen frame 1 and the limit area 2 may have the same size. . In addition, when the tracking area reaches the limit area 2 in constructing the camera, it is possible to use the selection knob to select whether to use the method disclosed in the present invention or another method. Conceivable.

As described above, the camera provided with the zoom lens according to the present invention is forcibly forced when the relationship between the limit area designated by the moving image capturing apparatus such as a video camera and the tracking gate is established. By moving the focal length to the short focal point side, the probability of the camera losing sight of the subject is reduced and the operability is improved.

[Brief description of drawings]

The drawings show an embodiment of a camera equipped with a zoom lens according to the present invention. FIG. 1 is an operation explanatory view, FIG. 2 is a zoom motor drive circuit, and FIG. 3 is a block circuit configuration diagram in a video camera. Reference numeral 1 is a photographing screen frame, 2 is a limit area, 4 is a power zoom switch, 7 is a zoom motor drive circuit, 8 is a power zoom motor, 16 is a CCD image sensor, 18 is a signal processing circuit, 21 is a color detection circuit, 25 Is a subject position detection circuit, 26 is a warning circuit, 27 is a tracking gate position determination circuit, 28 is a tracking gate size determination circuit, 29 is a comparison circuit, 30 is a limit area setting circuit, and 31 is a color designation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Fujiwara 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Plant (72) Masamichi Toyama 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Inside the Tamagawa Plant (72) Takashi Amizo, 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc.Inside the Tamagawa Plant, Canon Inc. (72) Masahiro Takei, 770, Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc., Tamagawa Plant (56) References JP-A-59-3802 (JP, A) JP-A-49-98913 JP, A) JP-A-55-162688 (JP, A) JP-A-57-123782 (JP, A)

Claims (1)

[Claims] 1. An image sensor for receiving an image formed by a zoom lens, a tracking gate determining means for determining a tracking gate according to an object, and the tracking gate for following the object based on an output signal of the image sensor. Subject detection means, determination means for determining a focus state based on the output signal of the image sensor in the tracking gate, focusing means for performing focus adjustment by the zoom lens based on the output of the determination means, and photographing Area setting means for setting a limit area in the screen, detecting means for detecting that the tracking gate has reached the limit area, and changing the focal length of the zoom lens to the short focus side by the output of the detecting means. A camera equipped with a zoom lens, which is equipped with a zooming means.