JPH04291308A - Camera device - Google Patents

Abstract

PURPOSE:To correct the focusing position of a zoom lens by means of a simple structure. CONSTITUTION:When the focal distance of the zoom lens 12 is short, the focusing position of a focusing lens 13 is corrected by reading data out corresponding focusing position stored in a memory 40. Also, when the focal distance of the zoom lens 12 is short, the focusing position of the focusing lens 13 is corrected by reading data out the point almost the intermediate point of the corresponding focusing position stored in the memory 40.

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 equipped with an autofocus mechanism.

0002

2. Description of the Related Art Conventionally, various so-called electronic still cameras have been developed that record still images as electrical video signals on magnetic disks. This electronic still camera requires focus adjustment by moving the focus ring or the like of the photographing lens, like a still camera using a normal silver halide film. In this case, some cameras have an autofocus mechanism that allows automatic focus adjustment. Conventionally, this autofocus mechanism detects the distance from the camera to the subject by some method, and moves the focus ring of the photographic lens in accordance with this distance information.

On the other hand, some video cameras detect focus information for autofocus control from the imaging signal itself and perform autofocus control without detecting distance (Japanese Patent Laid-Open No. 57-2085).
(See Publication No. 20, etc.). That is, when the focus adjustment of the lens is appropriate, the outline of the subject can be photographed clearly, so the image signal contains high frequency components. On the other hand, if the focus adjustment of the lens is not appropriate, the outline of the subject will be blurred and the image signal will not contain high-frequency components. Therefore, by detecting the amount of high-frequency components in the imaging signal, it is possible to detect whether the current focus adjustment state is appropriate or not, and autofocus control is performed.

[0004]The above-mentioned electronic still camera also uses a solid-state imaging device to obtain an electrical imaging signal, similar to a video camera, so the focus for autofocus control is determined from this imaging signal itself. A method for detecting information can be applied. By applying this autofocus method to electronic still cameras, there is no need to detect the distance from the camera to the subject, and the autofocus mechanism can be configured more easily than in still cameras that use silver halide film.

[0005]

By the way, zoom lenses are widely used as photographic lenses mounted on cameras of this type. By using this zoom lens as a photographic lens, the focal length can be changed continuously, making it possible to take photographs at any angle of view, from wide-angle to telephoto, for example.

By the way, in the case of this zoom lens,
There is an inconvenience that when the focal length is changed, the focus position also changes. In other words, even if the subject is accurately focused before changing the focal length and there is no change in the distance from the camera to the subject, if the focal length is changed,
The subject may become out of focus. In order to prevent this kind of focus deviation from occurring with a general zoom lens, when the zoom ring for focal length adjustment is rotated, a mechanical part such as a cam groove will slightly shift the focus adjustment lens. The focus position is corrected in conjunction with changes in the focal length by moving the focus position step by step.

However, the focus position correction mechanism, which is made up of mechanical parts such as cam grooves, has a relatively complicated structure, which makes the structure of the lens device that much more complicated, and also increases the weight of the lens device (that is, the camera device). There was a problem that the volume also increased.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a still camera that can correct the focus position of a zoom lens with a simple configuration.

[0009]

[Means for Solving the Problems] As shown in FIGS. 1 and 2, for example, the present invention provides a zoom lens 12 that magnifies an incident optical image, and a focusing lens that focuses the incident optical image. 13 and a motor 35 for driving the focusing lens 13, a zoom lens state detection means 38 for detecting the state of the zoom lens 12, and a focusing motor 38 for detecting the state of the focusing lens 13. and a storage means 40 for storing the position of the focusing lens 13 where the optical image is focused relative to the position of the zoom lens 12. When a shift from the first state with a long focal length to the second state with a short focal length is detected, the focusing lens corresponding to the position of the zoom lens 12 detected by the zoom lens state detection means 39 is detected. The position of the lens 13 is obtained from the storage means 40, the focusing lens 13 is moved to this position by the motor 35, and the movement from the second state to the first state is detected by the zoom lens state detection means 39. In this case, the motor 35 moves the focusing lens 13 to approximately the middle of the position range of the focusing lens 13 corresponding to the first position, thereby focusing.

0010

[Function] By doing this, 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 distance is adjusted based on certain corresponding data stored in the storage means. The focal position of the lens is adjusted so that the subject that was in focus before changing the focal length remains in focus. When the focal length of the zoom lens changes from short to long (i.e. from wide-angle to telephoto), it is adjusted to approximately the middle of the focal range set at this time, so there is a possibility that the subject will be in focus. It gets expensive.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates the entire photographing lens, and this photographing lens 10 includes a fixed front lens 1.
1, a zoom lens 12 that adjusts the focal length (i.e., adjusts the angle of view), and a master lens 13 that adjusts the focus (i.e., adjusts the focus).
The lens device is configured as an inner focus type lens device in which the lens is located closest to the image forming surface. In this case, this photographic lens 1
0, when adjusting the focal length by the zoom lens 12,
There is no mechanism for mechanically moving the master lens 13 so that the focus position (position in focus) remains constant.

[0013] Then, the image light passing through the photographing lens 10 is transferred to a solid-state image sensor (hereinafter referred to as a CCD imager) 2.
1, the CCD imager 21 converts the image into an electrical imaging signal, the imaging signal processing circuit 22 converts the imaging signal into a predetermined video signal, and the video signal is supplied to the recording circuit 23. do. After the recording circuit 23 performs recording processing, a video signal for recording is supplied to the magnetic head 24 disposed close to the magnetic disk 25, and the magnetic disk 25 is recorded with one field or one frame of still image signals. Record the video signal of the image.

[0014] Also, numeral 30 in the figure indicates a central control unit (CPU) that controls photographing with this camera, and this central control unit 30 is designed to be able to judge whether or not the photographed image is in focus. . That is, the image signal obtained by the image signal processing circuit 22 is supplied to the analog-to-digital converter 32 via the high-pass filter 31, and the analog-to-digital converter 32 converts only the data at a predetermined portion of one screen into digital data. Convert. In this case, the area setting circuit 44 controls the location (timing) of this conversion. This area setting circuit 44 is supplied with a predetermined signal from the imaging signal processing circuit 22, and the data supplied from the high-pass filter 31 to the analog-to-digital converter 32 is
Determine where the data is on the screen, and when it is a necessary location (i.e. the location to be sampled), analog
A control signal is supplied to the digital converter 32 to convert it into digital data.

[0015] Then, this analog-to-digital converter 3
2 supplies the digital data outputted to the adder circuit 33,
This adding circuit 33 adds data for one screen, and this one
The added value for the screen is supplied to the central control device 30.

Therefore, in the addition circuit 33, the high-frequency components included in the imaging signals at a predetermined location in one predetermined screen are added for one screen, and the added value of the high-frequency components of the imaging signals for one screen is obtained. is supplied to the central controller 30.

Then, the central control unit 30 determines the supplied addition data and performs focus adjustment so that the addition value of the high-frequency components extracted by the high-pass filter 31 becomes the largest. That is, the central controller 30 controls the drive circuit 3
The stepping motor 35 that moves the master lens 13 can be controlled via the stepping motor 35, which moves the master lens 13 via the stepping motor 35, so that when performing automatic focus adjustment, the master lens 13 is Move the lens 13. In this case, in this example, this automatic focus adjustment is performed when the shutter is in a half-pressed state.

Note that when the master lens 13 driven by the stepping motor 35 is at an infinite focus position, a photointerrupter 36 is configured to optically detect this fact. The detected data is supplied to the central controller 30 via the analog-to-digital converter 43. Then, from this infinite position, the stepping motor 35 is controlled by the central controller 30.
The position (focus position) of the master lens 13 can always be determined by the number of steps for driving the master lens 13. The number of steps that can be driven (i.e. variable range) changes depending on the focal length. For example, if the longest focal length is 100 steps, the shortest focal length is 40 steps.
Limited to steps.

In this case, in this example, when photographing is started and autofocus control is performed for the first time, initial settings are made so that the focus position can be determined. That is, within the central control device 30, the master lens 1
Lens position memory (not shown) that stores the position information of 3.
At the start of this shooting, the stepping motor 35 is driven under the control of the central controller 30 to move the master lens 13 in one direction to the infinite position, and the lens position data at this time is stored in the lens position memory. let

Note that the detection position of the photointerrupter 36 does not have to be infinitely far away.

Then, when the zoom lens 12 moves in this state and the detection data of the potentiometer 39, which will be described later, changes, the data of the position where the master lens 13 should be, which is stored in the lens position memory in the central control unit 30, is updated. do. Then, based on this updated data, the stepping motor 35 drives the master lens 13 to position the master lens 13 at an appropriate position.

In this example, 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 control device 30 is configured to be able to control the motor 38 that moves the zoom lens 12 via the drive circuit 37, and when the zoom switch 41 connected to the central control device 30 is operated, the motor 38 is controlled. Move the zoom lens 12 by
The focal length can be adjusted to either the telephoto side or the wide-angle side. In this case, the zoom lens 1 driven by the motor 38
2 is detected as voltage data by a potentiometer 39 serving as a zoom lens position detection section, and this detected data is supplied to the central control device 30 via an analog-to-digital converter 43. The position (focal length) of the zoom lens 12 can always be determined on the device 30 side.

Further, 40 in the figure indicates a non-volatile memory connected to the central control unit 30, and this memory 40 stores information on focus positions where the in-focus state is likely to be maintained when the focal length is changed. Information is stored in advance. That is, when the focal length of a zoom lens is changed, the in-focus point changes, and information on the amount of change 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 determined to one point, so the amount of change by which the corresponding focus position is adjusted is stored in the memory 40. Further, when the focal length is changed from the wide-angle side to the telephoto side, since there is a width in the corresponding focus position, the amount of change to be adjusted to the intermediate point within the corresponding predetermined width of the focus position is stored in the memory 40. .

For this reason, for example, when the zoom lens 12 changes the focal length while focusing on a certain subject, the master lens 1 for focusing on the subject changes.
The adjustment amount of 3 can be 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. Then, at the same time as the adjustment to change the focal length is performed, drive control data based on the read adjustment information is supplied to the drive circuit 34 of the stepping motor 35 that drives the master lens 13, and the focus position ( The master lens 13 is moved so that the focused position remains constant.

Further, 42 in the figure indicates a shutter switch,
This 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 the video signal on the magnetic disk 25. conduct. in this case,
This shutter switch 42 has three states: a half-pressed state, a fully pressed state, and an unpressed state.
It is designed so that the state can be distinguished, and photography is performed when it is fully pressed. Furthermore, when the button is pressed halfway, the automatic focus adjustment described above is performed. Next, Figure 2 shows the operation centered on focus control when taking pictures with the still camera device of this example.
Explain with reference to.

FIG. 2 shows the movable range of the master lens 13 as a focusing lens, and when the focal length is at its shortest (wide-angle), it is in focus at a predetermined position W1. Suppose there is. Here, when the focal length is changed to the longest state (telephoto), the focal position W1 at wide-angle
The focal position corresponding to is within the range T0. In this example, the memory 40 stores data on the amount of change that causes the position T1 to be the intermediate point within the focusing range T0, and based on this data, the central controller 30
The stepping motor 35 is controlled by the master lens 13.
is driven to the T1 position. This driving is performed, for example, when the zoom lens 12 moves and the focal length adjustment is completed. Alternatively, the focus position may be adjusted sequentially from the point at which the focal length adjustment is started.

[0028] By adjusting the position in the middle of the range that may result in focusing in this way, the possibility of focusing on the subject is highest, and the state of focusing on the subject is performed continuously. Probability is high.

Furthermore, when the focal length is changed from a long state (telephoto) to a short state (wide-angle), for example, when a position within the range T0 in FIG. 2 is selected and focused in the telephoto state, it corresponds to the wide-angle state. Since the focus position is only point W1,
Drive to this W1 point based on the data in the memory 40.

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

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

While the master lens 13 is being adjusted in accordance with the angle of view in this way, the shutter switch 4 is
When 2 is completely pressed, the video signal obtained by photographing is recorded on the magnetic disk 25.

As described above, according to the still camera device of this example, although the photographing lens 10 has a simple structure in which no focus position correction is performed during focal length adjustment using mechanical components, the zoom lens 12 At the same time as the angle of view is adjusted by moving the zoom lens 12, the focus position is corrected appropriately. remains in focus. In this case, it is particularly difficult to configure an inner focus type lens device like the present example to correct the focus position using a mechanism such as a cam groove due to its structure. Therefore, the effect of correction using only the data stored in the memory 40 is great.

Note that after the angle of view is adjusted from the wide-angle side to the telephoto side and the focus position is adjusted to the midpoint of the corresponding lens position, the focus is automatically adjusted by detecting the integral value. It may also be possible to focus more reliably. In this case, the focus position adjustment to the intermediate point has already been set to the position where it is most likely to be in focus, so as long as the subject does not move, the shift will be slight even if it is not in focus. There is a slight movement of the master lens 13 to bring it into focus. Therefore, automatic focus adjustment can be performed in a short time.

Furthermore, in the above embodiment, when the angle of view is adjusted to the telephoto side, the focus position is adjusted to the midpoint of the position of the corresponding lens 13, but the focus position is adjusted slightly from the midpoint. In some cases, the possibility of being in focus may be higher depending on the position. In such a case, adjustment data for a position slightly shifted from this intermediate point may be stored in the memory 40.

Furthermore, the present invention is of course not limited to the above-described embodiments, and can take various other configurations.

[0037]

Effects of the Invention According to the present invention, when the angle of view is adjusted using a zoom lens, a substantially in-focus state is maintained electronically based on adjustment information stored in advance. There is no need for a focus position correction means, and the configuration of the lens device and the camera device to which this lens device is attached can be simplified. Further, even when automatic focus adjustment is performed after adjusting the angle of view, since the state is close to an in-focus state, there is an advantage that automatic focus adjustment can be performed in a short time.

[Brief explanation of the drawing]

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

FIG. 2 is an explanatory diagram showing an adjustment state of one embodiment.

[Explanation of symbols]

10 Photography lens 12 Zoom lens 13 Master lens 21 CCD imager 22 Imaging signal processing circuit 25 Magnetic disk 30 Central control unit 31 High pass filter 33 Adder circuit 34, 37 Drive circuit 35 Stepping motor 38 Motor 36 Photo interrupter 39 Potentiometer 40 Memory 41 Zoom switch 42 Shutter switch 44 Area setting circuit

Claims (1)

[Claims] 1. A camera device comprising: a zoom lens that magnifies an incident optical image; a focusing lens that focuses the incident optical image; and a motor that drives the focusing lens. a zoom lens state detection means for detecting the state of the zoom lens; a focusing lens state detection means for detecting the state of the focusing lens; and a focusing lens state detection means for detecting the state of the focusing lens; storage means for storing the position of the focusing lens, and the zoom lens state detection means detects movement of the zoom lens from a first state with a long focal length to a second state with a short focal length. 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 focusing lens is moved to this position by the motor. let me,
When the zoom lens state detecting means detects a movement from the second state to the first state, the zoom lens state detecting means detects that the focusing lens is located approximately in the middle of the position range of the focusing lens corresponding to the first position. A camera device characterized in that focusing is achieved by moving the focusing lens by the motor.