JP3389622B2 - Focus position detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-focus position detecting device used in electronic still cameras and the like.

[0002]

2. Description of the Related Art Recently, an electronic still camera capable of recording and reproducing a color still image on a magnetic recording medium has been put into practical use in place of a camera using a silver salt film. By the way, in such an electronic still camera, a function of notifying where the in-focus position on the screen is is not considered. Therefore, particularly when the manual focus is used, the focus position cannot be clearly confirmed on the poor viewfinder display screen.

[0003]

As described above, in the conventional electronic still camera, since it is not possible to confirm where on the screen the in-focus position is located on the viewfinder, it is essential to make a mistake in confirming the in-focus position. There is a problem in that the subject may be out of focus and shooting may fail.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a focusing position detecting device which can easily know where on the viewfinder screen the focusing position is.

[0005]

According to the present invention, there is provided a lens system which is movable in the optical axis direction, and a means for displaying an image signal of an object imaged through the lens system as a video signal on a viewfinder screen. and means for integrating the high frequency component of the image signal of each block as well as divide object screen captured into blocks via the lens system, before
2 obtained before and after moving the lens system
The change in the integrated data is small from the integration result of the high frequency component of
Block with a large high-frequency component value as the in-focus position
The determination means and the means for blinking the display of the block corresponding to the focus position of the viewfinder screen based on the determination result of this means . Further, the present invention is
A lens system that is movable along the optical axis and an optical fine
And a transmissive L combined with this optical finder
A CD and a subject screen imaged through the lens system
Image signal of each block while dividing into multiple blocks
Means for integrating the high frequency component of the
And the product of the two high-frequency components obtained after moving
The change of the integrated data is small and the high frequency component
Means for determining a block with a large value of
According to the determination result of the means,
The display of the corresponding block blinks.
Has been.

[0006]

As a result, according to the present invention, the viewfinder
The display of the block corresponding to the in-focus position on the screen will start blinking. This allows the user to immediately know where the focus position is on the viewfinder screen from the blinking of the block display.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of the same embodiment. In the figure, reference numeral 1 is a lens system in which an optical axis CCD 2 of the lens system 1 is arranged, and a photographed image of a subject is photographed via the lens system 1
The image is formed on the image pickup surface of.

In this case, the lens system 1 is constructed so that it can be slightly moved in the optical axis direction. Also, CC
The timing of image capturing of D2 is controlled by the timing generator 3. The image signal picked up by the CCD 2 is given to the A / D converter 5 via the amplifier 4 and converted into digital data. Then, this data is sent to the signal processing unit 6, subjected to various signal processing such as extraction of a luminance signal and a color signal, and stored in the memory 7. The memory 7 stores one screen of image data.

The image data stored in the memory 7 is D /
It is sent to the A converter 8 and converted into an analog signal. Then, this analog signal is sent to a recording unit (not shown), is given as a video signal from the encoder 9 to the viewfinder 11 via the switching circuit 10, and is also sent to other monitors. The switching circuit 10 is for switching the video signal from the encoder 9 and the white level signal from the white level circuit 12 provided to the viewfinder 11, and the viewfinder 11 is controlled by timing signals φ 1, φ 2, and φ 3 from the CPU 13, which will be described later. The display of the white level signal and the video signal is switched in the block corresponding to the in-focus position.

Here, in the switching circuit 10, as shown in FIG. 2, the video signal from the encoder 9 is applied to the fixed contact a of the switching unit main body 101, and the white level signal from the white level circuit 12 is applied to the fixed contact b. The viewfinder 11 is connected to the movable contact point c which selects the fixed contact points a and b. The switching operation of the movable contact c is controlled by the output from the AND gate 102 to which the timing signals φ1, φ2, φ3 are given from the CPU 13.

Returning to FIG. 1, the image signal from the amplifier 4 is sent to the screen division integrator 14. Screen division integrator 1
4, for example, one screen is divided into 64 blocks as shown in FIG. 4 and the high frequency components in each block are integrated, and the integration result is given to the CPU 13.

The CPU 13 determines the block corresponding to the in-focus position from the result of each integration process in the screen division integrator 14 when the lens system 1 is slightly moved in the optical axis direction.
From this determination result, the viewfinder 1
1 determines whether the input to 1 is a white level signal or a video signal, and for example, determines the display timing of the white level signal and the video signal in the block corresponding to the focus position as shown in FIG. And horizontal timing signal φ2
, Φ3, and a timing signal φ1 for determining the cycle of the blinking period.

Reference numeral 15 is a timing circuit for controlling the display timing of the viewfinder 11. Next, the operation of the embodiment configured as described above will be described with reference to the flowchart of FIG. First, it is determined whether or not the manual focus is set (step 501), and if NO here, the routine shifts to an unillustrated autofocus routine. On the other hand, Y
If it is ES, it is determined whether or not the shutter switch is half pressed (step 501).

Here, if YES, the integration process is executed twice (step 503). In this case, when the shutter switch is half-pressed, the CCD is set through the lens system 1.
The image signal of the subject imaged in 2 is given to the A / D converter 5 via the amplifier 4, converted into digital data, stored in the memory 7, and sent to the D / A converter 8. It is converted into an analog signal, sent to a recording unit (not shown), and given from the encoder 9 as a video signal to the viewfinder 11 via the switching circuit 10.

In this state, the image signal from the amplifier 4 is
It is also sent to the screen division integrator 14, one screen is divided into 64 blocks as shown in FIG. 4, the high frequency components in each block are integrated, and these integration results are taken into the CPU 13. Then, when the CPU 13 finishes capturing the first integration result, the lens system 1 is slightly moved in the optical axis direction. Then, in the same manner as described above, the screen division integrator 14 integrates the high frequency components in each block, and these integration results are also taken into the CPU 13.

The CPU 13 determines the in-focus position from the results of these two integration processes (step 504). By the way, the relationship between the high frequency component obtained from the image signal and the lens position is as shown in FIG. 6, and at the in-focus position A, the high frequency component does not change even if the lens position is moved a little, and the integration result is Although it does not change so much, at the position B deviated from the in-focus position, the high-frequency component changes greatly even if the lens position moves a little, so the integration result also changes greatly.

From this, the CPU 13 determines the block in which the change of the integrated data is small and the value of the high frequency component is large from the two integration processes as the focus position. Then, based on the determination result, the display of the block corresponding to the in-focus position on the screen of the viewfinder 11 blinks (step 505).

In this case, as shown in FIG. 3, vertical and horizontal timing signals .phi.2 and .phi.3 for determining the display timing of the white level signal and the video signal in the block corresponding to the in-focus position on the screen of the viewfinder 11. And the timing signal φ1 for determining the cycle of the blinking period is the switching circuit 10
Sent to. Then, the switching circuit 10 receives the timing signals φ1, φ2, and φ3 from the AND gate 102.
Each time the output of the H level becomes H level, the movable contact c is switched to the fixed contact b, and the white level signal from the white level circuit 12 is sent to the viewfinder 11.
As shown in (a) and (b), the block A corresponding to the in-focus position on the screen of the viewfinder 11 is displayed blinking.

As a result, the user can know the in-focus position from the blinking position on the screen of the viewfinder 11. Such an operation is continued until the half-depressed state of the shutter switch is released in step 502, and the operation is ended after the shutter switch is fully depressed in step 506. The present invention is not limited to the above-mentioned embodiment, and for example, the focus position display can be carried out by appropriately modifying it within a range not changing the gist such as a combination of an optical finder and a transmissive LCD .

[0020]

According to the present invention, the display of the block corresponding to the focus position on the viewfinder screen is made to blink, so that the user can focus on the viewfinder screen from the blinking of the block display. It becomes possible to immediately know whether or not there is a position, the focus position can be easily confirmed, and it is possible to avoid inconveniences such as failure of photographing because the subject is out of focus.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a schematic configuration of a switching circuit according to an embodiment.

FIG. 3 is a diagram showing a timing signal given to a switching circuit of FIG.

FIG. 4 is a diagram showing a state of screen division in the screen division integrator of one embodiment.

FIG. 5 is a flowchart for explaining the operation of the embodiment.

FIG. 6 is a diagram for explaining determination of a focus position according to an embodiment.

FIG. 7 is a diagram showing a display example of a focus position on a viewfinder screen according to an embodiment.

[Explanation of symbols]

1 ... Lens system, 2 ... CCD, 3 ... Timing generator, 4
... Amplifier, 5 ... A / D converter, 6 ... Signal processing unit, 7 ... Memory, 8 ... D / A converter, 9 ... Encoder, 10 ... Switching circuit, 11 ... Viewfinder, 12 ... White level circuit, 13 ... CPU, 14 ... Screen division integrator, 15 ... Timing circuit.

Claims (2)

(57) [Claims] 1. A lens system movable in the optical axis direction, The image signal of the subject captured through this lens system is
Means to display on the viewfinder screen as a video signal
When, Multiple subject screens captured through the lens system
And the high frequency of the image signal of each block
Means for integrating the components,Obtained before and after moving the lens system, respectively
The change in the integrated data is small from the two high-frequency component integration results.
Focus and position the block with a large high frequency component value
Means for determining Based on the determination result of this means, the result of the viewfinder screen
A means to blink the display of the block corresponding to the focus position
An in-focus position detection device characterized by being provided. Wherein the lens system has to be movable in the optical axis direction, and the optical finder, the transmissive LCD in combination with the optical finder
And multiple subject screens captured through the lens system.
And the high frequency of the image signal of each block
Means for integrating the components and obtained before and after the movement of the lens system respectively
The change in the integrated data is small from the two high-frequency component integration results.
Focus and position the block with a large high frequency component value
And a determination result of this means to determine the focus position of the transmissive LCD.
And means for blinking the display of the corresponding block
An in-focus position detection device characterized by the above.