JP2874285B2 - Predictive drive autofocus device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. INDUSTRIAL APPLICATION Field of the Invention The present invention predicts a movement of a moving subject even when the moving subject is moving, and performs exposure in a precisely focused state by performing exposure. Related to the device.

B. Conventional Technology Conventionally, the movement of a subject is predicted from defocus amount data corresponding to the difference between the image plane position of the subject and the film surface by the taking lens before the shutter release, and the lens drive amount is calculated by (defocus amount + subject There is known a camera provided with a predictive drive auto-focus device that drives a photographic lens based on the calculated amount of movement correction and corrects a focus shift due to a change in subject distance from the time of distance measurement to the time of exposure. As a camera of this type, there is a camera in which a predictive drive mark is lit on a focus display section in the viewfinder during predictive drive autofocus.

C. Problems to be Solved by the Invention However, with the conventional predictive drive autofocus device, it is difficult to confirm whether the predictive drive autofocus device accurately tracks the moving object even if the predictive drive mark is lit. There's a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a predictive drive autofocus apparatus that accurately tracks a moving subject and indicates that the apparatus is operating.

D. Means for Solving the Problems The present invention will be described with reference to FIG. 1 showing an embodiment. The present invention relates to an image plane for calculating a moving speed of a subject image plane by a photographing optical system accompanying a subject movement. Moving speed calculation means 5a
Applied to a predictive drive autofocus device including: a subject movement determining unit 5b that determines whether the subject approaches or moves away based on the subject image plane moving speed calculated by the image plane moving speed calculating unit 5a. Big,
A display 7 for displaying a plurality of pictograms for imaging subjects of three sizes, medium and small, and a subject small and small when the subject movement determining means 5b determines that the subject is approaching.
A plurality of pictograms are sequentially turned on as if they are imaged as large and large, and when it is determined that the subject is moving away, a plurality of pictograms are sequentially turned on as if the subject is imaged as small, large and medium. Display control means 5d
By providing the above, the above object is achieved.

E. Operation The display control means 5d turns on the pictograms on the display 7 in the order of small, medium, and large when the moving object is judged to be approaching by the object movement judging means 5b, and when it is judged that the object is moving away, Since the subject is lit in the order of large, medium, and small, the subject is displayed as if it were approaching or moving away.

In the above sections D and E for describing the configuration of the present invention, the drawings of the embodiments are used for easy understanding of the present invention, but the present invention is not limited to the embodiments.

F. Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention.

The light beam from the subject that has passed through the taking lens 1 is guided to the AF sensor unit 4 via the main mirror 2 and the sub mirror 3. The focus detection device 4 calculates a defocus amount DF corresponding to a difference between a subject image plane formed by the photographing lens 1 and a predetermined imaging plane conjugate with the film plane by a focus detection optical system and an image sensor (not shown). To the control circuit 5 including

The control circuit 5 (display control means) determines the moving speed V0 of the subject image plane based on the defocus amount DF from the focus detection device 4.
And a subject movement determining unit 5b that determines whether the subject is stationary, approaches the camera, or moves away from the camera based on the moving speed V0 of the subject image plane. The movement of the subject is predicted based on the current and past defocus amounts DF obtained from the focus detection device 4 and the photographing lens drive amount (defocus amount DF).
And a predicted drive amount calculation unit 5c for calculating a predicted drive amount, and drives the photographing lens 1 by the drive amount via the lens drive unit 6.

Further, the control circuit 5 also has a display control unit 5d for displaying, on the display unit 7 in the finder, a state in which the subject being predicted and driven moves based on the result of the determination by the subject movement determination unit 5b. Each of the components 5a to 5d is realized by a microcomputer in the form of software.

In FIG. 1, a switch 8 is a power switch for turning on / off the power of the camera, a switch 9 is a half-press switch for detecting a half-pressed state of the shutter release, and a switch 10 is for detecting a fully-pressed state of the shutter release. This is a full-press switch.

FIG. 2 shows an example of a display unit 7 of an image size selector (not shown) for photographing a main subject in a composition according to a photographer's image. The display unit 7 according to the present embodiment is a pictographic display element for imaging subjects of three sizes, large, medium, and small.
When the subject approaches the camera as shown in FIG. 3, the display elements are turned on in the order of large → medium → small display elements 7a-7c as shown in FIG. 3, and as shown in FIG. When the camera moves away from the camera, the display elements are turned on in the order of small, medium, and large display elements 7a to 7c.

When the subject is stationary, the shooting distance x (mm) to the subject detected by an encoder (not shown) that generates a position signal corresponding to the extension amount of the taking lens 1
And the focal length f (mm) of the photographing lens 1 to calculate distance information (x / f). For example, when (x / f) <40, it is determined that the subject is a close-up view and a large-sized display element is turned on. And 40 ≦
When (x / f) ≦ 100, the subject is a middle view, and the medium-sized display element is turned on. When (x / f)> 100, the subject is considered to be a distant view, and the small-sized display element is turned on. .

Instead of the display 7 in the viewfinder, for example, an LCD display 7A is provided on the upper part of the camera body 11 as shown in FIG.
May be provided and displayed.

6 to 8 are flowcharts showing an example of a program for predictive driving AF executed by the microcomputer of the control circuit 5, and the operation of the present embodiment will be described with reference to FIGS.

When the predictive drive mode is started, the microcomputer starts executing the program shown in FIG. In step S1, it is determined by the switch 9 whether or not the shutter release is half-pressed. If the shutter release is half-pressed, the flow advances to step S2 to execute the half-press subroutine shown in FIG. 7; Proceed to.
In step S3, it is determined whether or not the shutter release is fully pressed by the full-press switch 10. If the shutter release is fully pressed, the process proceeds to step S4 to execute the full-press subroutine shown in FIG. Proceed to S5. In step S5, it is determined whether or not the power switch 8 is on. If the power switch 8 is on, the process returns to step S1, and if it is off, the execution of the program ends.

When the shutter release is half-pressed, execution of the half-press subroutine shown in FIG. 7 is started.

In step S10, a well-known focus detection process is performed by the focus detection device 4 to obtain the defocus amount DF1, and after a very short time wait in step S11, the process proceeds to step S11.
Proceed to step 12 to perform the focus detection processing again to
Find DF2. In step S13, based on the defocus amounts DF1 and DF2 obtained in the above steps, the moving speed V0 of the subject image plane by the photographing lens 1 is calculated, and the process proceeds to step S14. It is determined whether the object is approaching, moving away, or stationary. Note that the method of calculating the image plane moving speed is known in Japanese Patent Application Laid-Open No. 63-148218 and the description thereof is omitted.

If the subject is approaching the camera, go to step S15
Then, the pictographic display elements 7a to 7c of the display unit 7 shown in FIG. That is, as if the subject were approaching the camera, the first time through this step 15, the small-sized pictogram display element 7c, the second-time medium-size pictogram display element 7b, and the third-time large-size Are turned on in order, and all the display elements are turned off once in the fourth time, and then turned on again in the order of small, medium, and large from the fifth time.

If the subject moves away from the camera, go to step S16
Then, the display elements 7a to 7c are turned on in the order of large → middle → small so that the subject moves away from the camera. In this case, after turning on the small-sized display element 7c, all the display elements are turned off once, and then turned on again in the order of large, medium, and small from the next time.

When the subject is stationary, the distance information (x / f) to the subject is calculated in the step S17 by the above-described method. In the following step S18, when it is determined that the subject is a distant view based on the distance information, a step S19 is performed. Proceed to turn on the small-sized pictogram display element 7c, and if it is determined to be a middle view, go to step S20 to turn on the medium-size display element 7b, and if it is determined to be a near view, go to step S21. The large-sized display element 7a is turned on.

Upon completion of the processing in steps S15 to S21, the process returns to the program shown in FIG.

Next, when the shutter release is fully pressed, execution of a full-press subroutine shown in FIG. 8 is started.

In step S30, the above-described predicted drive amount of the photographing lens 1 is calculated, and after driving the photographing lens 1 via the lens driving unit 6, in step S31, a shutter mechanism (not shown) is driven to perform exposure. As a result, a better focus can be obtained for a moving subject during exposure. Further, in step S32, after taking up one frame of the photographic film through a film winding mechanism (not shown),
It returns to the program of FIG.

As described above, during the predictive drive focus, the predictive drive autofocus device normally operates by displaying the subject as approaching or moving away from the camera using the pictogram display unit 7 of the image size selector. It is possible to confirm that the user is tracking the moving subject.

Furthermore, the pictogram display section 7 of the image size selector
And the display unit of the predictive drive AF device, a new display space is not required, and the cost is reduced.

In the above embodiment, the focus detection is performed by the TTL focus detection method and the distance to the subject is obtained. However, the distance to the subject may be obtained by the external light triangulation method. Furthermore, although the display was performed using the pictograph display elements of three sizes, four or more pictograph display elements may be used. Furthermore, the shape of the pictograph is not limited to the embodiment, and may include symbols and marks. There may be. Furthermore, the control program of the predictive drive autofocus device is not limited to the present embodiment.

G. Effects of the Invention As described above, according to the present invention, during the predictive drive autofocus operation, when the subject comes close to the camera, the subject is displayed using the display device that displays pictograms of at least three sizes. The pictograms are illuminated in order as if they were imaged as small, medium, and large, and conversely, as they were far away, as they were imaged as small, medium, and small, making it easier to operate the predictive drive autofocus device. Can be confirmed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of one embodiment, FIG. 2 is a diagram showing a pictogram display unit for imaging a subject of three sizes, and FIG. 3 is a pictogram display when a moving subject approaches a camera. FIG. 4 is a view showing the lighting order of the elements, FIG. 4 is a view showing the lighting order of the pictogram display element when the moving subject moves away from the camera, FIG. 5 is a view showing a camera having an LCD display on the upper part of the camera body, and FIG. 8 to 8 are flowcharts showing an example of a control program for predictive drive autofocus. 5: microcomputer 5a: image plane movement speed calculation unit, 5b: subject movement determination unit 5c: predicted drive amount calculation unit, 5d: display control unit 7, 7A: display unit, 7a to 7c: display element 8: power switch, 9: Half-press switch 10: Full-press switch

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-288846 (JP, A) JP-A-1-194684 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 7/28 G03B 19/18

Claims (1)

(57) [Claims] An image plane moving speed calculating means for calculating a moving speed of a subject image plane by a photographing optical system in accordance with a moving of a subject, and an object based on the subject image plane moving speed calculated by the image plane moving speed calculating means. A predictive drive auto-focusing device including a subject movement determining unit that determines whether the subject approaches or moves away, wherein a display for displaying a plurality of pictograms for imaging subjects of at least three sizes, large, medium, and small; When the subject is determined to be approaching by the subject movement determining means, the plurality of pictograms are sequentially turned on as if the subject were imaged as small, medium, and large, and when it was determined that the subject was far away, the subject was large. Display control means for sequentially lighting the plurality of pictograms so as to make the images smaller, medium, and small. That prediction drive autofocus device.