JPH0728390B2 - Distance measuring field selection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a camera or the like that performs focus detection using a video signal from a distance measuring field in the output video signal of an image sensor,
The present invention relates to a distance measurement visual field selection device capable of arbitrarily selecting a distance measurement visual field position.

(Prior Art) An apparatus for automatically detecting or adjusting a focus using a video signal obtained by processing an output signal of an image pickup device includes a magazine "NHK Technology Research" Vol. No.86)
Many proposals have been made, including a paper entitled "Automatic Focus Adjustment of Television Cameras Using a Mountain Climbing Servo System" (published in 1965). This type of system utilizes, for example, a phenomenon in which a higher frequency component in a video signal (mainly a luminance signal) from an image pickup device increases as the image of a subject becomes sharper, and the high frequency component is extracted by some signal processing means. This is based on the principle of controlling the optical system so that the peak is reached and focusing the peak position.

By the way, in the conventional automatic focusing device of this type,
As shown in the figure, a video signal from the central portion of the image sensor is taken out to detect the focus, and the distance measuring field is fixed to the central portion of the finder. Therefore, it is necessary to position the subject to be focused (hereinafter referred to as the target subject) at the center of the entire field of view of the finder. For this reason, focus detection or focus adjustment is not possible when the target subject is in the peripheral part of the entire field of view, and when the target subject moves around, the camera should start and stop so that the target subject is always located in the center of the viewfinder. Since it had to be moved, there were many restrictions in defining the composition when using conventional autofocusing devices.

(Object) Accordingly, the present invention provides a ranging field selecting device capable of arbitrarily selecting a ranging field in real time and displaying the selected ranging field on an electronic viewfinder. The purpose is to enable automatic focus detection or automatic focus adjustment for target objects in the periphery of the entire field of view or target objects that move within the entire field of view, eliminating the above-mentioned restrictions when determining composition in conventional devices. Is what you are trying to do.

(Explanation by Embodiments) Means taken in the present invention in order to achieve the above object will be illustrated and described with reference to FIGS. 1 to 4. The following description will be made in the order of the configuration of one embodiment of the distance measuring visual field selection device of the present invention, its operation and other embodiments.

(Structure of an embodiment of a distance measuring visual field selection device of the present invention) (FIGS. 1 to 3) FIG. 1 is an example of distance measuring visual field divisions on an electronic viewfinder in a video camera embodying the present invention. In the figure, (A) shows an example in which the entire range of the subject visual field is divided, and (B) shows an example in which a required range is divided. In FIG. 1A, 1 indicates the entire range of the field of view of the subject, and in this case, the total range is set to 3 categories in total in the vertical and horizontal directions. Of these,
(A) shows a section corresponding to a distance measuring field position (FIG. 5) fixed in the center by a conventional device, and (B) shows a section designated as a distance measuring field in an embodiment described later. Same figure (B)
In the above, in the required range shown by 2 out of the entire range 1 of the field of view of the subject, 5 categories shown by (a), (c), (d), (e) and (f) are set.

These divisions can be set by a signal generated by the character generator 19 under the control of the microcomputer 18 described later without physically dividing the surface of the image pickup device, and as shown in FIG. Instead of setting the sections so that they do not overlap with each other, they may be set so as to partially overlap with the adjacent sections, or the range (area) of some of the sections may be set to be different from that of other sections. The contour display of the distance measuring field will be described later.

FIG. 2 shows the overall configuration of an embodiment of the distance measuring visual field selection device of the present invention. In the figure, 11 is a solid-state image pickup device constituted by a CCD or the like which is an example of image pickup means, 12 is a clock pulse generation circuit, A frequency divider 13 receives a clock pulse from the clock pulse generation circuit 12, divides the frequency, and divides the required frequency-divided signal into the solid-state imaging device 11 and a synchronization signal generation circuit 14 described later.
And output to the character generator 19. Reference numeral 14 is a synchronizing signal generating circuit, and 15 is a signal processing circuit, which performs required modulation and correction processing on the output signal of the solid-state image pickup device 11 to output a video signal (Fig. 3 (a)). The signals are combined by the encoder 16 with the sync signal to form a video signal ((b) in the figure).

Reference numeral 17 denotes a distance measuring field selecting means, which is a joystick here, but may be any other device capable of specifying the distance measuring field categories, for example, the same number of push button switches as the number of the distance measuring field categories. It may be arranged corresponding to. Reference numeral 18 denotes a microcomputer, which receives a signal from the joystick 17 and outputs a distance measurement visual field classification selection signal ((c) in the figure) to the character generator 19. The microcomputer 18 further supplies a gate signal to an analog switch 22 described later. charactor·
The generator 19 receives the frequency division signal from the frequency divider 13 and the distance measurement visual field classification selection signal, and outputs an area signal ((d) in the figure) which is a distance measurement visual field position designation signal to the signal synthesis circuit 20. Then, the signal synthesizing circuit 20 synthesizes the area signal and the video signal described above, transfers the synthesized video signal shown in FIG. 6 (e) to the electronic viewfinder 21, and the pulse portion of the video signal causes the finder surface to move. Display bright lines on both the left and right sides of the upper distance measuring field. The shaded portion in (b) of FIG. 1 (A) shows the bright line portion in an emphasized manner. On the other hand, the analog switch 22 transfers the video signal output from the signal processing circuit 15 to the automatic focus adjustment (AF) device 23 only while the gate signal from the microcomputer 18 is at a high level. The automatic focus adjustment device 23 performs focus adjustment by the above-described hill climbing control method, for example. Reference numeral 24 denotes a power-on / clear circuit, which inputs a clear signal generated when the apparatus is started up to the microcomputer 18, whereby the distance measuring field of view of the object field of view shown in (a) of FIG. Control so that it is located in the center. It should be noted that the microcomputer 18 and the character generator 19 have a function of displaying the distance measuring visual field described above, a focus / non-focus determination, a photo /
Other display functions such as white balance, exposure, and recording mode can be combined.

(Operation of an embodiment of the distance measuring visual field selecting device of the present invention) (FIGS. 1 to 3) Next, the operation of the distance measuring visual field selecting device shown in FIG. 1 and FIG. Will be described with reference to. Here, a case will be described where the joystick 17, which is an example of the distance measuring field selecting means, designates the distance measuring field classification (b) in FIG. 1 (A). In FIG. 3, the vertical axis represents the voltage of each signal, the horizontal axis represents time, 1H represents one horizontal scanning cycle, 1F represents one field scanning cycle, and the vertical synchronizing signal is shown for simplicity. Is omitted. Furthermore, in this embodiment, signals such as video signals and sync signals are signals based on the NTSC system.

First, a solid-state image pickup device (CCD) 11 which is an image pickup means is driven by a drive signal from a frequency divider 13 to convert an optical image into an electric signal, and the signal is shown in FIG. The video signal is converted into a video signal shown in the figure, combined with the horizontal synchronizing signal by the encoder 16, and supplied as an output video signal shown in FIG. On the other hand, the above-mentioned output video signal is sent through the analog switch 22 in FIG.
The signal is supplied to the automatic focus adjustment device 23 as a signal corresponding to the range-finding field division (b) shown in FIG.

In response to the selection of the distance measuring field division (b) by the joystick 17, the microcomputer 18 outputs a distance measuring field division selection signal shown in FIG. 7C, and the character generator 19 and this frequency divider 13 Area signal ((d) in the figure) which is a distance measurement visual field position designation signal in response to the frequency division signal from
Is output. In this example, since there are nine divisions of the distance measuring field of view in FIG. 1 (A), nine types of gate signals for controlling the analog switch 22 and the area signals are output. This area signal is a signal synthesis circuit.
The output video signal is combined at 20 and transferred to the electronic viewfinder 21 as a combined video signal shown in FIG. This allows electronic viewfinder 21
Then, the distance measuring visual field position selected by the joystick 17 is displayed by the bright lines on both the left and right sides of the position as shown in FIG. Therefore, according to the above apparatus, a signal (FIG. 3 (f)) of a portion corresponding to the distance measuring field section shown in (b) of FIG. 1 (A) is created and supplied to the automatic focus adjustment device 23. As a result, focus detection or focus adjustment can be accurately performed even when the target subject is in the section (b) above, and the above operations can be performed continuously to arbitrarily select the distance measurement field in real time. , Can be displayed on the electronic viewfinder 21. Furthermore, by controlling the power-on / clear circuit 24, when the device is started,
The distance measuring visual field can be positioned at the central portion (section (A) in FIG. 1A) which is fixed by the conventional video camera.

(Other Embodiment of Distance Measuring Field Selecting Device of the Present Invention) (Fourth Embodiment)
(FIG. 1) In order to set the bright line display on the upper and lower sides of the distance measuring field of (B) of FIG. Should be superimposed on the output video signal. For example, FIG. 3 (d)
Instead of the area signal of FIG. 2, high level is continuously applied between the first two pulses in the figure and between the two pulses in the horizontal scanning period at the position corresponding to the lower contour of (b) of FIG. In other horizontal scanning periods, the area signal and the output video signal, which are the same as those in FIG. 3D, may be combined and transferred to the electronic viewfinder 21. Further, instead of the whiteout display by the bright line display described above, a blackout display in which the luminance of this portion is particularly lowered may be performed.

As yet another display means, as shown in FIG. 4, the four corners of a predetermined distance measuring field section may be displayed in square brackets, or the luminance or color tone of the entire surface of the predetermined distance measuring field section may be changed to another display. It may be different from the part.

(Effect) As described above, according to the present invention, an arbitrary section is selected from a plurality of preset distance measuring field sections, and a distance measuring field position designation signal and image pickup means which are generated in accordance with the selection. Since the output signal of is combined and transferred to the electronic viewfinder, it is possible to arbitrarily select the ranging field in real time and display the selected ranging field on the electronic viewfinder. This makes it possible to perform automatic focus detection or automatic focus adjustment for a target subject in the peripheral portion of the entire field of view or a target subject moving within the entire field of view, and it is possible to remove the constraint that existed in determining the composition in the conventional device. .

[Brief description of drawings]

FIG. 1 (A) is an explanatory view showing an example of a distance measuring field section in the distance measuring field selecting device of the present invention, and FIG. 1 (B) is an explanatory view showing another example of the distance measuring field section, FIG. Is a block diagram of an embodiment of the distance measuring visual field selecting device of the present invention, FIG. 3 (a)
2A to 2F are waveform charts showing signals at the portions a to f in FIG. 2, and FIG. 4 is a modification of the contour display of the distance measuring field on the electronic viewfinder in the distance measuring field selecting device of the present invention. FIG. 5 is an explanatory view showing a portion for extracting a focus adjustment signal from the image sensor in the conventional automatic focus adjusting device. DESCRIPTION OF SYMBOLS 11 ... Solid-state image sensor which is an example of image pickup means, 14 ... Synchronous signal generating circuit, 16 ... Encoder, 17 ... Joystick which is an example of distance measuring field selection means, 18 ... Microcomputer, 19 ...... Character generator, 20 ……
Signal synthesizer circuit, 21 ... Electronic viewfinder, 22 ... Analog switch, 23 ... Automatic focus adjustment device.

Claims (1)

[Claims] 1. An image pickup means, an electronic viewfinder, a selection means capable of setting a distance measuring visual field to an arbitrary section among a plurality of sections set on a screen, and a distance measuring section selected by the selection section. A focus detection unit that detects a focus state based on an output signal of the image pickup unit corresponding to the field of view, and a distance measurement visual field position designation signal regarding a position of the distance measurement visual field in the screen according to selection by the selection unit. Generating means, means for synthesizing the output signal of the image pickup means and the distance measuring visual field position designation signal and transferring the combined signal to the electronic viewfinder, and the distance measuring visual field is selected by the selecting means when the apparatus is activated. And a means for automatically setting the initial position in the substantially central portion of the screen regardless of the position, and a distance measuring visual field selection device.