JPS60226280A - Range finding visual field selecting device - Google Patents

Abstract

PURPOSE:To enable automatic focus detection or automatic focus adjusting on a target object which is in peripheral part of whole visual field by selecting a range finding visual field optionally in real time, and displaying the selected range finding visual field on a view finder. CONSTITUTION:A solid-state image pickup element 11, an image pickup device, is driven by a driving signal from a frequency divider 13 and an optical image is converted to electric signals and taken out as output video signals through a signal processing circuit 15 and an encoder 16. On the other hand, a microcomputer 18 outputs a range finding visual field selection signal according to range finding visual field division by a joy stick 17. A character generator 19 receives this signal and a frequency dividing signal from the frequency divider 13 and outputs an area signal. The area signal is synthesized with the output video signal in a synthesizing circuit 20 and transferred to an electronic view finder 21 as a synthesized video signal. Consequently, the selected position of the range finding visual field is indicated by bright lines on the view finder.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a camera or the like that performs focus detection using a video signal from a ranging field of view in an output video signal of an image sensor.
The present invention relates to a distance measuring field of view selection device that can arbitrarily select a distance measuring field of view position.

(Prior art) A device that automatically detects or adjusts the focus using a video signal obtained by processing the output signal of an image sensor is described in the magazine r NHK Technology Research, Vol. 17, No. 1. 8
Many proposals have been made, including the paper ``Automatic focus adjustment of television cameras using the mountain climbing method'' in No. 6) (published in 1965). In this type of method, for example, the sharper the image of the subject, the more the video signal from the image sensor (
It is based on the principle of taking advantage of the phenomenon in which high frequency components increase in the luminance signal (mainly luminance signals), extracting these high frequency components using some kind of signal processing means, controlling the optical system so that this becomes the peak, and focusing on the peak position. It is something.

By the way, in the conventional automatic focusing device of this type, the fifth
As shown in the figure, focus detection was performed by extracting a video signal from the center of the image sensor, and the distance measurement field of view was fixed at the center of the finder.

Therefore, it is necessary to position the subject to be focused on (hereinafter referred to as the target subject) in the center of the entire field of view of the finder. Therefore, if the target subject is located at the periphery of the entire field of view, focus detection or focus adjustment may not be possible.
Furthermore, if the target subject moves around, the camera must be moved all the time so that the target subject is always located in the center of the viewfinder, so there were many restrictions when determining the composition using conventional automatic focus adjustment devices. (Objective) Therefore, the present invention provides a ranging field selection device that can arbitrarily select a ranging field in real time and display the selected ranging field on an electronic beehive finder. The purpose of this is to enable automatic focus detection or automatic focus adjustment even for target subjects located at the periphery of the entire field of view or target subjects moving within the entire field of view, and to overcome the limitations in determining the composition of the conventional device described above. This is what we are trying to remove.

(Explanation based on Examples) Hereinafter, the means taken in this invention to achieve the above object will be exemplified and explained with reference to FIGS. 1 to 4, etc. The following description will be made in the order of the structure, operation, and other embodiments of one embodiment of the distance measuring field selection device of the present invention.

(Configuration of one embodiment of the distance measuring field of view selection device of the present invention) (Figs. 1 to 3) Fig. 1 shows an example of the distance measuring field of view division on the electronic bee finder in a video camera embodying the present invention. The figure (B) shows an example in which the entire range of the subject's field of view is divided, and the figure (B) shows an example in which a required range within the same range is divided. In the figure, 1 indicates the entire range of the subject's field of view, and here, the entire range is set into 3 sections both vertically and horizontally, and a total of 9 sections. Among these, (a) is the distance measurement field of view fixed in the center using the conventional device (Figure 5).
(b) indicates a section to be designated as a range-finding field of view in an embodiment described later. In the same figure (B), five divisions indicated by (a), (/i, ni), (e), and (e) are set in the required range indicated by 2 out of the entire range 1 of the subject field of view.

These divisions can be set using signals generated by a character generator 19 under the control of a microcomputer 18, which will be described later, without physically dividing the surface of the image sensor. Instead of setting each section so that they do not overlap with each other, set them so that they partially overlap with adjacent sections, or set the range (area) of some sections to be different from other sections. You can also do it. Note that the outline display of the distance measurement field of view will be described later.

FIG. 2 shows the overall configuration of an embodiment of the distance measuring field of view selection device of the present invention, in which reference numeral 11 denotes C1C1D, which is an example of the imaging means.
12 is a clock pulse generation circuit @Ip, 1. q is a frequency divider which receives a clock signal from the clock pulse generation circuit 12, divides the frequency, and sends the required frequency-divided signal to the solid-state image sensor 11, a synchronization signal generation circuit 14, and a character generator, which will be described later. Output to 19. 14 is a synchronization signal generation circuit, 15
is a signal processing circuit that performs necessary modulation and correction processing on the output signal of the solid-state image sensor 11 to generate a video signal (see Fig. 3).
a)) is output, and this video signal is combined with the above-mentioned synchronization signal in the encoder 16 to form a video signal (FIG. 2(b)).

Reference numeral 17 denotes a distance measuring field of view selection means, which is assumed to be a joystick here, but any other device that can specify the distance measuring field of view divisions may be used. They may be arranged according to the same category.

A microcomputer 18 receives a signal from the joystick 17 and outputs a distance measurement visual field division selection signal (FIG. 3(C)) to the character generator 19.

The microcomputer 18 receives the frequency division signal from the frequency divider 13 and the distance measurement field division selection signal, and sends an area signal (FIG. 2(d)), which is a distance measurement field position designation signal, to the signal synthesis circuit 2o. The signal synthesis circuit 20 synthesizes this area signal and the above-mentioned video signal, transfers the synthesized video signal shown in FIG. Alternatively, bright lines are displayed on both the left and right sides of the distance measurement field on the viewfinder surface. In addition, Figure 1 (4)
The shaded area in (b) emphasizes this bright line area. On the other hand, the analog switch 22 is connected to the signal processing circuit 15
The above-mentioned video signal which is the output of the microcomputer 18
The r-t signal is transmitted to the automatic focusing (AF) device 23 only during the period when the r-t signal is at a high level. Automatic focus adjustment device 23
For example, focus adjustment is performed using the aforementioned hill-climbing control method.

Reference numeral 24 is a war-on clear circuit, and a clear signal generated when the device is started is inputted to the microcomputer 18, so that the field of view for distance measurement is always set as shown in (a) in Fig. 1 when the device is started. Control the subject so that it is located in the center of the field of view. The microcomputer 18 and character generator 19 are designed to have other display functions such as focus/out-of-focus determination, photo/white balance, exposure, and recording mode in addition to the above-mentioned distance measurement field of view display function. Yes.

(Operation of one embodiment of the range-finding field selection device of the present invention) (Figs. 1 to 3) Next, regarding the action of the range-finding field-of-view selection device shown in Figs. 1 and 2, the waveform diagram in Fig. 3 is shown. This will be explained with reference to. Here, the joystick 17 is an example of distance measuring field selection means.
The case of specifying the distance measuring field of view section (b) in FIG. 1(3) will be explained below. In FIG. 3, the vertical axis represents the voltage of each signal, the horizontal axis represents time, 1H represents one horizontal scanning period, IF represents one field scanning period, and for simplicity, the vertical synchronizing signal is not shown. is omitted. Further, in this embodiment, it is assumed that signals such as video signals and synchronization signals are based on the NTSC system.

First, the solid-state image sensing devices (C, C, D) 1, which are image sensing means, are driven by a drive signal from a frequency divider 13 to convert an optical image into an electric signal, and the signal is converted into a third electric signal by a signal processing circuit 15. The video signal is converted into the video signal shown in FIG. 13A, combined with a horizontal synchronizing signal by the encoder 16, and supplied to a usage device (not shown) as the output video signal shown in FIG. On the other hand, the above output video signal is supplied to the automatic focus adjustment device 23 via the analog switch 22 as a signal corresponding to the distance measurement field of view section (b) shown in FIG. It is done.

The microcomputer 18 outputs a ranging visual field segment selection signal shown in FIG. In response to the frequency-divided signal from , it outputs an area signal ((d) in the same figure) which is a distance measurement field of view position designation signal. In this example, since the distance measuring field of view shown in FIG.
Each type will be output. This area signal is combined with the above-mentioned output video signal in the signal combining circuit 2θ, and is transferred to the electronic viewfinder as a combined video signal shown in (,) in the same figure. Now, the distance measuring field position selected by the joystick 17 is displayed by bright lines on both the left and right sides, as shown in FIG. 1(A) (b). Therefore, according to the above device, a signal (FIG. 3(f)) corresponding to the ranging field section shown in FIG. According to
Even if the target subject is in the (ol) category mentioned above, focus detection or focus adjustment can be performed accurately, and the above operations can be performed continuously to arbitrarily select the distance measurement field of view in real time. In addition, when the power-on/clear circuit 24 is controlled, when the device is started up, the distance measurement field of view is always fixed at the central part (the central part) set by a conventional video camera. It can be located in category (a) of figure 1).

(Another embodiment of the distance measuring field of view selection device of the present invention) (Fig. 4) In order to further set the bright line display on both upper and lower sides of the distance measuring field of Fig. 1 (g) and (b), It is sufficient to superimpose a signal having a high level within a predetermined range at positions corresponding to the upper and lower contours on the output video signal.

For example, instead of the area signal in FIG. 3(d), the horizontal scanning period at the position corresponding to the lower contour of FIG. The signal becomes high level υ continuously between the two pulses, and during the other horizontal scanning periods, the area signal and output video signal, which are the same as in FIG. 3(d), are combined and transferred to the electronic viewfinder 1 =-. Bye. Furthermore, instead of the white line display using the bright line display described above, a black line display may be used in which the brightness of this portion is particularly reduced.

As another display means, as shown in FIG. It may be different from the part.

(Effects) As described above, according to the present invention, any one of a plurality of distance measuring field sections set in advance is selected, and the distance measuring field position designation signal and the imaging means are generated in accordance with the selection. Since the output signal of the AF is combined with the output signal and transferred to the electronic viewfinder, the distance measurement field of view can be arbitrarily selected in real time and the selected distance measurement field of view can be displayed on the electronic viewfinder. It also enables automatic focus detection or automatic focus adjustment for target subjects located at the periphery of the entire field of view or for target subjects moving within the entire field of view, and eliminates the limitations that existed when determining composition with conventional devices. Can be removed.

[Brief explanation of the drawing]

Figure 1 (B) is an explanatory diagram showing an example of the distance measurement field division in the distance measurement field selection device of the present invention, Figure 2 (B) is an explanatory diagram showing another example of the distance measurement field division. A block diagram of an embodiment of the distance measuring field of view selection device of the invention, FIGS. 3(a) to 3(f) are waveform diagrams showing the signals of portions a to f in FIG. 2, respectively, and FIG. An explanatory diagram showing a modified example of the outline display of the distance measurement field on the electronic viewfinder in the distance measurement field of view selection device. Fig. 5 is an explanatory diagram showing a portion for extracting the focus adjustment signal from the image sensor in the conventional automatic focus adjustment device. It is a diagram. Explanation of symbols 11...Solid-state image sensor, which is an example of an imaging means, 14.
...Synchronization signal generation circuit, 16...Encoder, 17.
・・Joystick which is an example of distance measurement field of view selection means,
18... Microcomputer, 19... Character generator, 20... Signal synthesis circuit, 21...
-Electronic viewfinder, 22...analog switch, 23...automatic focus adjustment device. Figure 3 (C) [hi]]shi 几-11----- (Cl) □------ (+)

Claims (1)

[Scope of Claims] An imaging means; an electronic viewfinder; a selection means for selecting an arbitrary division from among a plurality of preset distance measurement field divisions; and a distance measurement field position designation according to the selection by the selection means. A distance measurement field selection device comprising: means for generating a signal; and means for combining an output signal of the imaging means and the distance measurement field position designation signal and transmitting the synthesized signal to the viewfinder.