JP3038954B2 - Camera device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera device suitable for use in an electronic still camera, and more particularly to a camera device provided with an autofocus mechanism.

[0002]

2. Description of the Related Art Various types of so-called electronic still cameras for recording a still image on a magnetic disk as an electric video signal have been developed. In this electronic still camera, it is necessary to perform focus adjustment by moving a focus ring or the like of a photographing lens, as in a still camera using a normal silver halide film. In this case, there is an automatic focus mechanism that allows automatic focus adjustment. Conventionally, as this autofocus mechanism, the distance from the camera to the subject is detected by some method, and the focus ring of the photographing lens is moved according to the distance information.

On the other hand, some video cameras detect focus information for autofocus control from an image pickup signal itself and perform autofocus control without detecting a distance (Japanese Patent Laid-Open No. 57-2085).
No. 20, etc.). In other words, when the focus adjustment of the lens is proper, the outline of the subject can be clearly photographed, and thus the image signal contains a high-frequency component. On the other hand, when the focus adjustment of the lens is not appropriate, the subject is photographed with the outline blurred, and the imaging signal does not include the high frequency component. Therefore, by detecting the amount of the high frequency component in the image signal, it is possible to detect whether or not the current focus adjustment state is appropriate, and the auto focus control is performed.

In the above-mentioned electronic still camera, an electric image signal is obtained by using a solid-state image sensor or the like as in the case of a video camera. Therefore, a focus for auto focus control is obtained from the image signal itself. A method of detecting information can be applied. By applying this autofocus method to an electronic still camera, there is no need to detect the distance from the camera to the subject, and the autofocus mechanism can be configured more easily than a still camera using a silver halide film.

[0005]

Incidentally, a zoom lens is widely used as a photographing lens mounted on this type of camera. By using this zoom lens as a photographing lens, the focal length can be continuously changed, and for example, it is possible to photograph at an arbitrary angle of view from wide angle to telephoto.

By the way, in the case of this zoom lens,
When the focal length is changed, there is a disadvantage that the focus position also changes. That is, before the focal length is changed, the subject is accurately focused, and even if the distance from the camera to the subject does not change, if the focal length is changed, the subject may not be focused. . In a general zoom lens, in order to prevent such a focus shift, when the zoom ring for adjusting the focal length is rotated, the focus adjustment lens is slightly reduced by a mechanical component such as a cam groove. The focus position is corrected in conjunction with the change in the focal length by moving the focus position.

However, the focus position correcting mechanism composed of the mechanical parts such as the cam grooves has a relatively complicated structure, which complicates the structure of the lens device and the weight of the lens device (ie, the camera device). And there is a disadvantage that the volume is increased.

In view of the above, it is an object of the present invention to provide a still camera capable of correcting the focus position of a zoom lens with a simple configuration.

[0009]

According to the present invention, for example, FIG.
As shown in FIG. 2 and FIG.
Lens 12 and the focus of the incident optical image.
A focusing lens 13 and a mode for driving the focusing lens 13
Camera 35 having a zoom lens
Zoom lens state detecting means for detecting the state of the zoom lens39
And a focusing lens shape for detecting the state of the focusing lens 13
State detecting means 36 and light with respect to the position of the zoom lens 12.
Record the position of the focusing lens 13 where the scientific image is focused
Storage means 40 and the zoom lens state detection means 39
Therefore, the first state in which the focal length of the zoom lens 12 is long
When movement from the camera to the second state with a short focal length is detected
Is detected by the zoom lens state detecting means 39.
Focusing lens 13 corresponding to the position of the zoom lens 12
Is obtained from the storage means 40, and the motor 35
The focusing lens 13 is moved by the
From the second state to the first state by the state detecting means 39
When the movement of the focus is detected, the focusing corresponding to the first position is performed.
Approximately in the middle of the position range of the lens 13 by the motor 35.
The focus is adjusted by moving the focusing lens 13.
It is intended to be.

[0010]

With this arrangement, when the focal length of the zoom lens changes from a long state to a short state (that is, from the telephoto side to the wide-angle side), the focusing lens is set on the basis of certain correspondence data stored in the storage means. The focus position of the lens is adjusted, and the subject that has been in focus before the focal length is changed is kept in focus. When the focal length of the zoom lens changes from a short state to a long state (that is, from the wide-angle side to the telephoto side), the focal length is adjusted to approximately the middle of the focal range set at this time. Get higher.

[0011]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 denotes an entire photographing lens. This photographing lens 10 includes a fixed front lens 11, a zoom lens 12 for adjusting a focal length (ie, an angle of view), and a focus adjustment ( That is, focus adjustment)
And a master lens 13 for performing
Reference numeral 3 designates an inner focus type lens device closest to the image forming surface. In this case, the photographing lens 10 does not include a mechanism for mechanically moving the master lens 13 so that the focus position (focus position) becomes constant when the focal length is adjusted by the zoom lens 12.

The image light passing through the photographing lens 10 is converted into a solid-state image sensor (hereinafter referred to as a CCD imager) 2.
An image is formed on one phase plate, converted into an electric image signal by the CCD imager 21, converted into a predetermined image signal by the image signal processing circuit 22, and supplied to the recording circuit 23. I do. After a recording process is performed by the recording circuit 23, a video signal for recording is supplied to a magnetic head 24 arranged close to the magnetic disk 25, and a static image for one field or one frame is supplied to the magnetic disk 25. The video signal of the image is recorded.

In the figure, reference numeral 30 denotes a central control unit (CPU) for controlling the photographing by the camera, and this central control unit 30 can determine whether or not the photographed image is in focus. . That is, the imaging signal obtained by the imaging signal processing circuit 22 is supplied to an analog / digital converter 32 via a high-pass filter 31, and the analog / digital converter 32 converts only data at a predetermined position in one screen into digital data. Convert. In this case, the area to be converted (timing) is controlled by the area setting circuit 44.
The data supplied from the high-pass filter 31 to the analog-to-digital converter 32 by the supply of a predetermined signal from the imaging signal processing circuit 22 is 1
Judge which part of the screen is the data, and if it is a necessary part (that is, a part to be sampled),
A control signal is supplied to the digital converter 32 to convert it into digital data.

The analog / digital converter 3
2 is supplied to the addition circuit 33,
This adder circuit 33 adds data for one screen, and this 1
The added value for the screen is supplied to the central control device 30.

Therefore, in the adder circuit 33, the high-frequency component included in the imaging signal at a predetermined position in one predetermined screen is added for one screen, and the added value of the high-frequency component of the imaging signal for one screen is added. Is supplied to the central controller 30.

The central control unit 30 determines the supplied added data and adjusts the focus so that the added value of the high-frequency components extracted by the high-pass filter 31 is maximized. That is, the central control device 30 is provided with the drive circuit 3
4, the stepping motor 35 for moving the master lens 13 can be controlled. When performing the automatic focus adjustment, the master stepping motor 35 is controlled by the stepping motor 35 so that the added value of the high frequency component becomes maximum. The lens 13 is moved. In this case, in this example, the automatic focus adjustment is performed when the shutter is half-pressed.

Incidentally, when the master lens 13 driven by the stepping motor 35 is at the infinity focus position, this is optically detected by the photointerrupter 36. Is supplied to the central control unit 30 via the analog / digital converter 43. Then, the stepping motor 35 is controlled from the infinity position by the control of the central controller 30.
The position (focus position) of the master lens 13 can always be determined based on the number of steps for driving. The number of steps that can be driven (that is, the variable range) varies depending on the focal length.
Limited to steps.

In this case, in this embodiment, when the photographing is started and the auto-focus control is performed for the first time, initialization is performed so that the focus position can be determined. That is, the master lens 1 is provided in the central controller 30.
Lens position memory (not shown) for storing position information of No. 3
At the start of photographing, the master lens 13 is moved in one direction by the driving of the stepping motor 35 under the control of the central controller 30 so that the master lens 13 is located at infinity, and the lens position data at this time is stored in the lens position memory. Let it.

The detection position of the photo interrupter 36 does not have to be at infinity.

In this state, when the zoom lens 12 moves and the detection data of the potentiometer 39 described later changes, the data of the position where the master lens 13 should be stored in the lens position memory in the central control device 30 is updated. I do. Then, based on the updated data, the master lens 13 is driven by the stepping motor 35 to move the master lens 13 to an appropriate position.

In this embodiment, the angle of view (focal length) of the zoom lens 12 is also adjusted under the control of the central controller 30. That is, the central controller 30 is capable of controlling the motor 38 for moving the zoom lens 12 via the drive circuit 37. When the zoom switch 41 connected to the central controller 30 is operated, the motor 38 To move the zoom lens 12,
The focal length can be adjusted to the telephoto side or the wide-angle side. In this case, the zoom lens 1 driven by the motor 38
The position 2 is detected as voltage data by a potentiometer 39 as a zoom lens position detection unit, and the detected data is supplied to the central control device 30 via an analog / digital converter 43, thereby enabling central control. The position (focal length) of the zoom lens 12 can always be determined on the device 30 side.

In the figure, reference numeral 40 denotes a non-volatile memory connected to the central control unit 30. This memory 40 has a focus position which is likely to be maintained in focus when the focal length is changed. Information is stored in advance. That is, when the focal length of the zoom lens is changed, the focal point changes. The information of the change amount is stored for each focus position. In this case, in this example, when the focal length is changed from the telephoto side to the wide-angle side, the corresponding focus position is fixed at one point, and thus the amount of change to be adjusted to the corresponding focus position is stored in the memory 40.
When the focal length is changed from the wide-angle side to the telephoto side, the corresponding focus position has a width. Therefore, the amount of change to be adjusted to the intermediate point among the corresponding predetermined-width focus positions is stored in the memory 40. .

For this reason, for example, when the focal length is changed by the zoom lens 12 while focusing on a certain subject, the master lens 1 for focusing on this subject is used.
The adjustment amount of 3 is found from the information stored in the memory 40.

The adjustment information stored in the memory 40 is read out under the control of the central controller 30 when the zoom lens 12 is adjusted to change the focal length. At the same time as the adjustment for changing the focal length is performed, the drive control data based on the read adjustment information is supplied to the drive circuit 34 of the stepping motor 35 for driving the master lens 13, and the focus position ( The master lens 13 is moved so that the focus position is constant.

In the figure, reference numeral 42 denotes a shutter switch.
The shutter switch 42 is connected to the central control device 30, and when the shutter switch 42 is pressed, the central control device 30 performs predetermined operation control for photographing, and records a video signal on the magnetic disk 25. Do. in this case,
The shutter switch 42 has three states: a half-pressed state, a half-pressed state, a fully-pressed state, and a non-pressed state.
The state can be distinguished, and the photographing is performed in a state where it is completely pressed. When the camera is half-pressed, the above-described automatic focus adjustment is performed. Next, an operation centering on focus control when photographing is performed by the still camera device of the present embodiment will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 2 shows the movable range of the master lens 13 as a focusing lens. When the focal length is in the shortest state (wide angle), the lens is in focus at a predetermined position W1. Suppose you have Here, when the focal length is changed to the longest state (telephoto), the in-focus position W1 at the wide angle is set.
Is in one of the ranges T0.
Here, in the present example, data of the amount of change to be the position T1, which is an intermediate point in the focusing range T0, is stored in the memory 40, and the central control device 30
The stepping motor 35 is controlled by the master lens 13
Is driven to the position of T1. This driving is performed, for example, when the zoom lens 12 moves and the adjustment of the focal length ends. Alternatively, the adjustment of the focus position may be performed sequentially from the time when the adjustment of the focal length is started.

By adjusting to an intermediate position in a range where focusing may be performed in this way, the possibility of best focusing on the subject becomes highest, and the focusing state on the subject is continuously performed. Probability is high.

When the focal length is changed from a long state (telephoto) to a short state (telephoto), for example, a position in the range T0 in FIG. Since the focus position is only W1 point,
The memory 40 is driven to the point W1.

In FIG. 2, a indicates a change in the position of the master lens 13 at infinity ∞, and b indicates a change in the position of the master lens 13 at a close distance.

By adjusting in this way, when the angle of view changes from the telephoto side to the wide-angle side, the in-focus state of the subject at the same position is continuously performed.

While the adjustment of the master lens 13 corresponding to the angle of view is performed, the shutter switch 4
A video signal obtained by photographing when the button 2 is completely pressed is recorded on the magnetic disk 25.

As described above, according to the still camera apparatus of the present embodiment, the zoom lens 12 has a simple structure in which the focus position is not corrected at the time of adjusting the focal length by a mechanical mechanism component as the photographing lens 10. When the angle of view is adjusted by moving the zoom lens, the correct focus position is corrected. Keeps in focus. In this case, in particular, it is difficult to configure the inner focus type lens device as in this example so that the focus position is corrected by a mechanism such as a cam groove from a structural point of view. Therefore, the effect that can be corrected only by the data stored in the memory 40 is great.

After the angle of view is adjusted from the wide-angle side to the telephoto side, and the focus position is adjusted at the intermediate point of the corresponding lens position, automatic focus adjustment is performed by detecting the integral value. Then, the focus may be made more reliably. In this case, the focus is already set at the position where it is most likely to be in focus by adjusting the focus position to the intermediate point, so that even if the subject is not in focus, the deviation is small even if the subject is not in focus. There is a slight movement of the master lens 13 to bring the lens into focus. Therefore, automatic focus adjustment can be performed in a short time.

In the above embodiment, when the angle of view is adjusted to the telephoto side, the focus position is adjusted to the intermediate point of the position of the corresponding lens 13, but it is slightly shifted from the intermediate point. The position may be more likely to be in focus. In such a case, the adjustment data at a position slightly shifted from the intermediate point may be stored in the memory 40.

The present invention is not limited to the above-described embodiment, but may take various other configurations.

[0037]

According to the present invention, when the angle of view is adjusted by the zoom lens, the substantially in-focus state is maintained electronically based on the adjustment information stored in advance, so that the photographing lens can be mechanically adjusted. Since the focus position correcting means is not required, the configuration of the lens device and the camera device to which the lens device is attached can be simplified. In addition, even when the automatic focus adjustment is performed after the angle of view is adjusted, there is an advantage that the focus can be automatically adjusted in a short time because the state is close to the in-focus state.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an adjustment state according to an embodiment.

[Explanation of symbols]

 Reference Signs List 10 photographing lens 12 zoom lens 13 master lens 21 CCD imager 22 imaging signal processing circuit 25 magnetic disk 30 central controller 31 high-pass filter 33 addition circuit 34, 37 drive circuit 35 stepping motor 38 motor 36 photointerrupter 39 potentiometer 40 memory 41 zoom switch 42 Shutter switch 44 Area setting circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B ⁷ /02-7/105 G02B ⁷ /12-7/16 G02B 7/28-7/40 H04N 5 / 222-5/257

Claims (1)

(57) [Claims] 1. A camera device comprising: a zoom lens for enlarging an incident optical image; a focusing lens for focusing the incident optical image; and a motor for driving the focusing lens. Zoom lens state detecting means for detecting the state of the zoom lens; focusing lens state detecting means for detecting the state of the focusing lens; and the focusing of the optical image with respect to the position of the zoom lens. Storage means for storing the position of the focusing lens, wherein the movement of the zoom lens from the first state having a long focal length to the second state having a short focal length is detected by the zoom lens state detecting means. In this case, the position of the focusing lens corresponding to the position of the zoom lens detected by the zoom lens state detection means is obtained from the storage means, and the position is obtained by the motor. It moved the focusing lens by said zoom lens state detecting means, the second
When the movement from the state described above to the first state is detected, the focusing lens is moved by the motor to a substantially middle position range of the focusing lens corresponding to the first position. A camera device characterized in that the camera is focused.