JPS6128915A - Camera - Google Patents

Abstract

PURPOSE:To let a photographer know that tracking operation is off currently by providing a means which warns that a subject to be tracked moves away from the center part of a photographic image plane beyond a specific range in such a case. CONSTITUTION:When the subject goes out of the photographic image plane or limit area as the specific area in it, a limit area setting circuit 18 is controlled with a horizontal synchronizing signal fH and a vertical synchronizing signal fV generated by a synchronizing signal generating circuit 10 to set the limit area BA according to photographer's settings. The limit area BA is provided so as to perform tracking operation within the area, and an arithmetic circuit 19 decides whether the current position of a tracking visual filed is within a manually set limit area BA or not according to output signals of the limit area setting circuit 18 and a gate moving circuit 6. Then, when the circuit decides that the position of the tracking visual field, therefore, the position of the tracked subject on the image plane goes out of the limit area BA, the tracking visual field is returned to an initial position, e.g. position corresponding to the center part of the photographic image plane.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a camera equipped with an automatic tracking focus detection device, and particularly relates to a camera equipped with an automatic tracking focus detection device. Concerning means of warning.

(Background Art) In a camera equipped with a conventional automatic focusing device with negligible difference, such as a video camera, the subject (hereinafter referred to as When the focus detection target object (in this example, a person) moves, an object at a different distance from the target object (a person) moves.
In this example, the subject (in this example, the house) is in focus, and the person, the subject of focus detection, is out of focus, so there is a drawback that the subject of focus detection must always be placed at the center of the screen due to the screen configuration. For this reason, methods have been proposed to make the distance measurement field of view variable, but these methods allow the photographer to change the distance measurement field of view by operating a knob or the like, and this is difficult to do when the subject moves during shooting. It is difficult to maintain the distance measurement field position always above the focus detection target object using these knobs.

In order to eliminate the above drawbacks, the applicant first sets a movable tracking field of view, extracts the features of the object to be ranged with respect to this tracking field of view, stores the extracted features,
The presence or absence of movement of the object is detected based on the memorized characteristics and the newly extracted characteristics of the object to be ranged, and the distance measurement field of view is tracked to the movement of the object according to the relative movement of the object. We have proposed a moving automatic tracking focus detection device (Patent Application No. 105897 of 1981, title of the invention ``Automatic tracking focus detection device''), but in implementing this proposal, as will be detailed later. If the tracked subject moves away from the center of the shooting screen by exceeding a predetermined range, the focus detection target may be moved to, for example, another object that is expected to appear at or near the center of the screen. For switching purposes, etc., it is desirable to issue a warning that the tracked subject has moved relatively away beyond a predetermined range.

(Purpose) The present invention eliminates the above-mentioned drawbacks of conventional automatic focus detection devices, automatically detects the moving position of a moving subject, and moves the distance measurement field of view to track the movement of the subject. To provide a camera equipped with a means for giving a warning when a tracked object moves away beyond a predetermined range from the center of a photographic screen when performing focus detection or focus adjustment.

(Description based on Examples) Hereinafter, with reference to FIGS. 1 to 13, etc., the means taken in this invention to achieve the above object will be exemplified and explained. The following explanation is an overall explanation of an embodiment of the camera of the present invention, as well as a limit area setting means, a subject movement detection means, and an automatic focus detection means in the same embodiment, regarding an example in which features of a tracked subject are extracted using color signal information. and the focus detection mark setting means and the operations of the embodiments of the present invention.

(Overall description of the embodiment f of the camera of the present invention) (Fig. 1) Fig. 1 shows the main parts of an embodiment of the camera according to the present invention, and in the figure, 1 indicates the photographic optical system. A lens group for focus adjustment, 2 is an example of an imaging means C, C, D,
This shows a solid-state image sensor such as . As is well known, the solid-state image sensor 2 is controlled by a 1° image sensor drive circuit (not shown) to photoelectrically convert light from a subject incident on its light-receiving surface. This photoelectrically converted signal is amplified by a preamplifier (not shown), subjected to various correction processes in the signal processing circuit 3, and color difference signals (R-Y), (B-Y ) and a luminance signal Y are created. These color difference signals and luminance signals are sent to encoder 1.
At step 5, the signal is combined with a synchronizing signal to form an output video signal, for example, an NTSC signal, and is supplied from an output terminal 16 to a device to be used, for example, a video deck.

The above color difference signals (R, -Y) and (B-Y), and if necessary, the luminance signal Y are input to the movement detection circuit 5 via the tracking gate circuit 4, and the same circuit detects the moving direction of the subject. The amount of movement is detected. Here, since the movement between the subject and the camera is relative, the above movement of the subject is
In addition to cases where the camera is fixed and the subject moves, cases where the subject stops and the camera moves, or cases where both move together, the present invention is applicable to any of the above cases.

In the tracking gate circuit 4, the gate pulse generation circuit 11-J
, eJ4-+μmk J<11+1jiP-, the gate position for the signal of the song is set. As a result, the position of the tracking field of view is determined for extracting the features of the subject and the features of the background, for example, in the manner shown in FIGS. 5 to 8, which will be described later. In other words, a range of the color difference signals and the like to be input to the movement detection circuit 5 is determined, and movement of the subject is detected based on a change in this signal. This object movement detection signal is supplied to a gate movement circuit 6, which generates a signal for moving the gate position of the tracking gate circuit 4, that is, the tracking field of view position, in accordance with the movement of the object to be tracked. This signal is the gate pulse generating circuit 11
A gate noculus is formed for extracting a color difference signal at a position corresponding to the movement of the tracked object. The gate pulse generation circuit 11 operates in synchronization with the horizontal synchronization signal f and the vertical synchronization signal fv generated by the synchronization signal generation circuit 10. Note that the synchronization signal generation circuit 10 is controlled by a signal obtained by frequency-dividing a clock pulse generated by a clock pulse generation circuit (not shown) that controls the timing of the entire apparatus, and furthermore, the above-mentioned image sensor driving circuit, for example, uses this frequency division. The encoder 15 described above is controlled by the synchronization signal, etc., and various types of synchronization control are performed, but since these synchronization control means are well known in video signal processing systems, a detailed explanation will be omitted. In addition, illustrations are omitted except for parts particularly related to the detailed description of the present invention. Further, details of the movement detection circuit 5 will be described later with reference to FIGS. 5 to 8.

On the other hand, the luminance signal Y is inputted to an automatic focus detection device 8 via a distance measurement gate circuit 7, and focus detection or focus adjustment is performed by the same device. In the ranging gate circuit 7, the luminance signal Y is generated by the gate pulse generated by the gate pulse generating circuit 11.
The gate position is set to the same relative position as the tracking gate, thereby determining the range of the luminance signal Y that is input to the automatic focus detection device 8 for detecting the focus of the subject (hereinafter referred to as the distance measurement field of view). . Note that in the embodiments of the present invention, the tracking field of view and/or distance measurement field of view can be displayed on a display device such as an electronic viewfinder as necessary, but this is not an essential means.

In FIG. 1, the tracking gate circuit 4 and the ranging gate circuit 7 are provided separately, but both gate circuits may be provided in common, or the latter may be connected after the former and the distance measurement gate circuit 7 may be set by the former. The distance measurement field of view may be set in an even smaller area within the tracking field of view.

However, in any case, both fields of view must be set at the same relative position, in particular with the same center position, during the tracking operation. In the example shown in FIG. 1, the tracking field of view and the distance measurement field of view can each be set to arbitrary sizes. Furthermore, if the size of one or both of the fields of view is automatically adjusted by a gate size determining circuit (not shown) according to the shooting distance and the focal length of the lens, the tracking field of view of the optimum size or ( and) a distance measurement field of view can be obtained.

An automatic focus detection device 8 connected after the distance measurement gate circuit 7 performs automatic focus detection according to known means, and its output signal controls the lens drive device 17, and its drive motor drives the lens group l. drive When the focal point is detected, the control loop described above stops operating, and the lens group 1 also stops at that position. A specific example of the automatic focus detection means will be described later with reference to FIG.

The position information obtained from the gate movement circuit 6 is formed into a signal, which is added to the output video signal (NTSC signal) from the encoder 15 in an adder circuit 13, and displayed as an image on a display device such as an electronic viewfinder (EVF) 14. A mark indicating the signal and focus detection target object (for example, the ti-th
FM) in the figure is displayed. The details of the character Φ generator 12 will be described later with reference to FIG.

Next, the tracking visual field return means in the embodiment shown in FIG. 1 will be explained. First, the limit area setting circuit 18 and the calculation circuit 19
is an example of the main component parts for returning the tracking field of view to the initial position when the subject moves out of the shooting screen or a specific area of the limit area, and among these, the limit area setting circuit 18 includes: Under the control of the horizontal synchronizing signal fH and vertical synchronizing signal fV generated by the synchronizing signal generating circuit IO, a limit area indicated by BA in FIG. 11, for example, is set according to the settings of the photographer. The limit area BA is provided for performing tracking operations only within the limit area BA, and the current position of the tracking field of view is determined in advance in the arithmetic circuit 19 according to the output signals of the limit area setting circuit 18 and the gate movement circuit 6. It is determined whether it is within the manually set limit area BA. When it is determined that the position of the tracking field of view, and hence the position of the tracked object on the screen, has left the limit area BA, the tracking field of view is returned to the initial position, for example, a position corresponding to the center of the photographic screen. To explain the means φ for this purpose by way of example, one of them is the arithmetic circuit 1
9 to reset the movement detection circuit 5 and gate movement circuit 6, and move the gate position of the tracking gate circuit 4, which is controlled by the gate pulse generated by the gate pulse generation port W1111, to a position corresponding to the above-mentioned initial position. It is. Note that in this invention, the limit area is a means of determining the range in which the tracking operation is performed, and does not necessarily need to be displayed on the viewfinder, etc. Also, the limit area is usually a area within the entire surface of the photographing screen. can also be set as a narrow range, or as a narrower range within a part of the shooting screen.

As another means of returning the tracking field of view to its initial position, in order to perform stable tracking operations when the subject is moving rapidly, instead of resetting it immediately after the subject leaves the limit area BA, The zero time setting circuit 21 and timer 22, which can be configured to perform the operation after a settable predetermined time, are provided for this purpose. The operating time is determined. When it is determined that the tracked object has left the limit area BA, the arithmetic circuit 19 transfers the control signal a to the movement detection circuit 5 and the gate movement circuit 6 to stop the operation of these circuits, and starts the timer 22. Transfer a control signal to start the operation. The timer 22 is
During its operation, the control signal C is sent to the character generator 1.
2. Transfer to the lens driving device 17 and warning circuit 20.

As a result, the character and generator 12 stop displaying the focus detection mark, and the lens driving device 17 stops its operation, so that the focus detection state determined by the position of the lens group 1 at that time is maintained. Furthermore, the warning circuit 20 generates a warning that the tracked object has left the limit area BA, and notifies the photographer of this fact or that the tracking operation is currently stopped. As specific means for this purpose, various means are possible, such as flashing the boundary line (frame) of the limit area BA or generating an audible sound signal.

When the predetermined time set by the time setting circuit 21 has elapsed, the operation of the timer 22 ends, and the gate position of the tracking gate circuit 4 determined by the movement detection circuit 5 and the gate movement circuit 6 is determined by the control signal d. The tracking field of view is returned to the initial position (
For example, the movement detection circuit 5 starts the object movement detection operation, which will be described later, again, and when the control signal C ends, the character generator 12 and the lens driving device 17 start the operation. Once restarted, the warning circuit 20 stops its operation and the automatic tracking operation is performed again. It should be noted that the limit area setting circuit 18 can be set by the photographer's operation.
When the entire shooting screen is set as the limit area, or when the entire shooting screen is fixedly set as the limit area, it is determined that the tracked subject has gone outside the shooting screen, and the tracking field of view described above is determined. , and operations related to this are performed. Further, in this specification, the meaning of the term "the subject moves out of the photographic screen or out of the limit area" will be described later with reference to FIG. 4. Note that the gate position of the ranging gate circuit 7 is also returned to a position corresponding to the center of the photographing screen following the tracking gate circuit 4.

(Limit area setting means in the embodiment of this invention) (First
(Figs. 2 to 4) Next, the embodiment of the present invention will be described with reference to Figs. 2 to 4. The limit area setting means in the previous example will be explained. Second
In the figure, 30.31 indicates the boundary line of the limit area BA, and by manual operation of the knob 40 in FIG. 3(A),
The boundary line 30.31 that determines the position of the direction moves left and right,
Moreover, the position is fixed by operating the lock button 41. Similarly, the boundary lines 32 and 33 that define the position in the y direction are moved up and down by operating the knob 42 in FIG. 4B, and their positions are fixed by operating the lock button 43.

That is, by operating the knobs 40 and 42, the limit area BA
The position of can be set variably, but the position of
Add one more knob in both directions, and set the border lines 30 and 31.
, similarly, 32 and 33 may be set independently, and the size of the limit area BA may also be set variably, depending on the operation of the above knob and lock button.
In order to generate a signal indicating the position 3, the positions of the horizontal scanning lines corresponding to these boundary lines (corresponding to 32° and 33) and the positions of the horizontal scanning lines whose upper and lower ends are these horizontal scanning lines are required. What is necessary is to select a specific position (corresponding to 30 and 31).

To do this, for the former, count the number of horizontal scanning lines in the l field and select the horizontal scanning line with the number corresponding to the position of the boundary line 32, 3.3 set by the knob 42, etc., and for the latter. generates a pulse train by multiplying the horizontal synchronizing signal frequency, counts from the start of the horizontal scanning period, and sets the boundary line 30 with the knob 40 etc.
．． Alternatively, you can generate triangular waves that are synchronized with the horizontal and vertical synchronizing signals, respectively, and move these triangular waves to the border lines (set by knobs 40 and 42, etc.). 30
, 31) and (32°33) to generate a rectangular wave, and generate a pair of pulses corresponding to the front and rear ends of these rectangular waves. What is necessary is to take the logical sum of the rectangular wave and the other pair of pulses.
(Refer to Japanese Patent Publication No. 384, title of the invention "Video Camera"), and may also be performed by means similar to the character generator 12 described later.

FIG. 4 shows the timing relationship of the signals created as described above for one horizontal scanning period, and (a)
2 shows the video signal in a simplified manner, (b) shows the limit area, specifically the position where the boundary line 30.31 in FIG. 2 intersects with the horizontal scanning line, and (C) shows the (a) signal. and (b)
(d) is the limit area width in the X direction (defined by boundary lines 30 and 31) in FIG. 2, (e) is the gate position by the tracking gate circuit 4 in FIG. 1, (f) shows the time axis, respectively. In this example, (d)
The signal indicating the limit area width is low level in the limit area and high level in other parts. Further, the tracking field of view is determined by the signal (e) indicating the gate position.

Although FIG. 4 does not show a signal representing the limit area in the y direction of FIG. 2, this limit area is also set in the same manner as shown in FIG. The limit area BA described above does not necessarily need to be displayed on a display device, but in order to display it on a display device such as the electronic viewfinder 14, the output signal of the limit area setting circuit 18 is sent to the character generator 12 or directly to the electronic viewfinder 14. What is necessary is to supply it to the viewfinder 14 and display it.

In the arithmetic circuit 19, in order to determine whether the gate position by the tracking gate circuit 4, that is, the tracking field of view exists within the limit area BA, the position on the time axis of the signal Ce) in FIG. 4 or the signal (d ) and 'signal (e). That is, the former is the tracked subject, in other words, the signal indicating the gate position is the fourth one.
Assuming that we move from right to left in the figure, (T2- Tl ) <
T K, or as moving from left to right (T4 T
3) This is performed by calculating in the calculation circuit 19 whether the relationship <TK (here, TK is a positive constant determined by design) is satisfied. Generally, the position within the limit area BA of the tracking field of view can be found by calculating (T2-TI)/(T4-Tl). Also, in the latter case, the signal (d)
If the logical sum of and signal (e) is at a low level, the marginal debt area H
If it is within A and at a high level, it is determined that it is outside the limit area BA. When it is determined that the tracking field of view is outside the limit area BA, or has moved from the center of the limit area BA to the outside of the area, and is approaching within a certain range (for example, the above-mentioned TK) with respect to the boundary line. , the arithmetic circuit 19 sends, for example, the above-mentioned reset signal to the movement detection circuit 5 and the gate movement circuit 6, and in conjunction with this, for example, in the above-mentioned case, or when the subject moves relatively from the center of the shooting screen to the vicinity of the boundary edge. and move to the above (T
2-T1)<TK or (T4-T3)<TK.

(Subject movement detection means in the embodiment of the present invention) (Figs. 1, 5 to 8) Next, the movement of the object to be tracked is detected and tracked, and the tracking gate circuit 4 of Fig. 1 A specific example of the movement detection circuit 5 for moving the gate position, that is, the tracking field of view, will be described with reference to FIGS. 5 to 8. The specific example below is an example in which the features of the tracked object are extracted as color signal information, but the features of the object can also be extracted using information such as a luminance signal, the shape of the object, temperature, or characteristic contrast in the object. This can also be done using .

The following object movement detection and automatic tracking means can be summarized as follows:
Some parameters representing the characteristics of the object, such as the color of the object and the background, are extracted with respect to the tracking field of view set by the tracking means, the extracted characteristics are stored, and the stored characteristics are combined with the newly extracted characteristics. Based on the characteristics of the subject, detect whether or not the subject is moving, and if the subject moves, detect the moving direction or moving position, and move the tracking field of view to follow the movement of the subject. Along with the movement, the distance measuring field of view is moved in the same positional relationship.

In principle, the tracking field of view has a two-dimensional extent, but to simplify the explanation, it is shown in Fig. 5 (A).
Assume that the tracking field of view has a one-dimensional extension extending in the horizontal direction as shown in FIG. Also, the tracking field of view is A, B,
Suppose that it is divided into three parts (hereinafter each part is referred to as a pixel) of C. Note that in order to configure a two-dimensional tracking field of view, for example, pixels may be provided that extend vertically above and below pixel B or A, B, and C in the same figure as the center.

Color difference signal obtained as a time series signal from each pixel above (
As shown in FIG. 6, integration circuits 50a and 50b, sample hold (
S/H) circuits 51a, 51b and A/D conversion circuit 52a
, 52b perform integration, sample hold, and A/D conversion processing, and store them in memories 53a and 53b, respectively. This stored value is applied to each pixel A, B and C.
When plotted on the orthogonal coordinates of (R-Y) and (B-Y), for example, 0 is displayed as shown in FIG.
In the figure, each point A O + B O and CG is 1'''''''
, $51iU (A) o"・BR"cog! il'
#.

represents the signal extracted from the Here, from pixel B, a signal representing only the clothes of the person who is the subject, for example, is transmitted.
It is assumed that signals are extracted from pixels A and C, in which signals representing the subject's clothing and the background are added. Furthermore, assume that the background colors on the left and right sides of the subject in the figure are different.

Therefore, points AO and Co have different positions on the color difference signal coordinates.

Next, when the subject shown in Fig. 5 (A) moves to the right within the screen as shown in Fig. 5 (B), the ratio of the subject to the background in pixels A and C changes, resulting in The signals obtained from A and C change as shown in FIG. 7 A1 and C1, respectively. On the other hand, since pixel B remains within the object as shown in FIG. 5(B), the signal obtained from pixel B hardly changes if the clothing is almost monochromatic. Therefore, here, for simplicity, it is assumed that Bl=B. In this case, as shown in FIG. 7, the point C1 approaches the point Bo (=Bx), and the point A1 approaches the point Bo (
-Bx), the line segment BICI becomes the line segment BoC
, and the line segment AIBI becomes thicker than the line segment AOB. Conversely, if line segment BIC, becomes larger than line segment BoC, and line segment AIB, becomes smaller than line segment AOB, the subject is moving to the left in Figure 5 (B). . Assuming that the background color is the same on both the left and right sides of the subject, when the subject moves to the right in Figure 5 (CB) within the screen, the above point A1 will occupy a position on the extension of the line segment AoB. , point C1 is located on the line segment BoCO. This invention can be applied to either of the above cases.

In order to detect the movement of the tracked object using the above-mentioned phenomenon, 1, for example, it is sufficient to detect the change in the length of the line segments AB and BC. The above pixels A and B.

The movement detection circuit 5 detects the color of the subject with respect to C.
A signal representing the newly extracted color of the object and a signal stored in the memory are stored in the memory of the camera, for example, through manual mechanical input means (registration of object characteristics). The comparison is made to detect whether or not the subject has moved, and if the subject has moved, for example, the direction of movement. The above processing is performed according to the average value during 1/60 seconds, which is the period of one field of the television signal, or during a period of several fields thereof. In the following, both will be explained as being processed in one field period.

FIG. 8 shows an example of a specific circuit for executing the above processing, and this circuit also shows details of the movement detection circuit 5 of FIG. 1. The (RY) signals and (B-
Y) from the (R-) signal in FIG.
Length DA of line segments AO, B on coordinates Y) and (B-y)
O and BO are determined and stored in the memory 61a. From the next field signal, DAl, B1 or D
AI-80 is required. Here, for simplicity, B1=
Considering the case of BO, DAI , s z =, DA
z-n.

The divider 62a calculates DAl, B1/DAO-BO. This value is compared with the first threshold value set by the threshold setting device 63a in the comparison circuit 64a, and if there is a change exceeding the threshold value, "1" is output to the movement determination circuit 65. Then, DCl, 81/DCO・BO is calculated by the circuit from the distance calculation circuit 60b to the comparison circuit 64b, and if there is a change in this that exceeds the second threshold set by the threshold setting device 63b, the comparison circuit 64b outputs "l" to the movement determination circuit 65. To explain specific numerical examples, in the several examples shown in FIG. , BO=2.2°Dcl・a t
/Dco, B O=0.36, so the comparator circuit 6
Only 4a outputs "loo." In this case, the movement determination circuit 65 sets the gate setting timing to a predetermined period (for example, N
In the case of the TSC method, a signal is generated that is delayed by about 1/125 of one horizontal scanning period. Conversely, when only the comparison circuit 64b outputs "1", the movement determination circuit 65 generates a signal that advances the gate setting timing by the above-mentioned predetermined time. The latter case is when the subject moves to the left in FIG.

Therefore, in response to the output "1" of the comparison circuit 64a or 64b, the movement determination 1 circuit 65 determines the gate setting timing.
For example, by generating a signal that changes by the above-mentioned predetermined time and having the gate moving circuit 6 and gate pulse generating circuit 11 control the gate circuits 4 and 7 according to this signal,
It is possible to move the tracking field of view and the distance measurement field of view in the direction in which the subject moves, and to perform focus detection at that position.

(Automatic focus detection means in the embodiment of this invention) (First
Although the automatic focus detection device 8 shown in FIG. 1 can utilize known means, a method of detecting focus using high frequency components in a luminance signal will be described as an example. In FIG. 9, 70 is a bandpass filter, 71 is a level detection circuit, and 72 is a focusing direction detection circuit.The bandpass filter 70 extracts the outline component, that is, the high frequency component, from the output luminance signal of the gate circuit 7 in FIG. The level of this high-frequency component is detected by a level detection circuit 71, and the focusing direction detection circuit 72 controls the detection level so that this detection level becomes maximum. A signal representing the direction is output to the lens driving device 17 described above.

In carrying out the present invention, in addition to the above-mentioned means, suitable known means such as infrared TT
L focus detection means or the like can be used.

(Focus detection mark setting means in the embodiment of this invention)
(FIGS. 1 and 10) In the embodiment of the present invention, a focus detection mark (FM in FIG. 11) indicating a subject to be focus detected is set by the character generator 12, for example. The character generator 12 is supplied with a horizontal synchronization signal fH and a pattern reading synchronization signal fV from a synchronization signal generation circuit IO,
Further, the gate moving circuit 6 supplies a signal indicating the position of the tracking field of view, that is, the position of the subject. Note that instead of the synchronization signal, the frequency-divided signal obtained by dividing the clock pulse generated by the clock pulse generation circuit (the synchronization signal generation circuit 1o is controlled by this frequency division signal) is directly supplied to the character number generator 12. The character generator 12, which may be used as a main character, receives these signals and generates a focus detection mark signal in the manner shown in FIG. That is,
10i) is a video signal generated by the signal processing circuit 3 in FIG. 1, and FIG. Figure (c) shows the focus detection mark position WM selection signal generated based on the output of the gate moving circuit 6, and Figure (d) shows the area generated by the character generator 12 in response to this focus detection mark position selection signal. The signal, (e) in the figure shows a composite video signal in which this area signal and the output video signal are added in the adding circuit 13, and this composite video signal is transferred to the electronic viewfinder 14, and its pulse portion is A bright line showing the outline of the focus detection mark is displayed on the finder surface.In order to display the focus detection mark FM on the finder surface, pixels A, B, and C1 in FIG. It may also be displayed. Further, the electronic viewfinder 14 may display the limit area BA as necessary, and the focus detection mark FM and the limit area B.
In order to display A on the viewfinder surface, instead of the white (bright line) display described above, it is necessary to use a black display with the brightness of the outline area particularly lowered, or to change the brightness or color tone of these entire areas compared to other parts. It is also possible to display the

(Function of the embodiment of this invention) (Fig. 1, Fig. 11 to Fig. 1)
(Figure 3) Figure 11 shows the function of the limit area BA in the embodiment of the present invention, especially when the tracked object O1 moves outside the photographing screen or to the limit area B□ in the sense defined above. □7□F, 1E1□' This is only for explaining the function of returning to a position corresponding to the center of the field area BA.

First, let us assume that the relative movement between the camera and the subject is done, for example, by panning the camera.
(B) shows the initial state, and (B) shows that after a certain amount of time has passed and the camera is moved to the right on the screen, subject 01 moves relatively to the left on the screen, and the limit area BA is moved. This indicates that the boundary has been reached. In this example, when the state shown in FIG. 1B is reached, for example, a reset signal is sent from the arithmetic circuit 19 in FIG. That is, the gate position is returned to a position equivalent to the initial position, and thereby the tracking field of view is returned to the initial position. When the tracking field of view returns to the initial position, if there is a next subject 02 at or near the same position, this subject 02
The features of the object are registered again, and tracking is performed for the same object. FIG. 11(C) shows this state, in which the previous subject 01 has left the limit area HA, and the focus detection mark FM indicates the next subject 02. In addition, in the above process, the subject 01 or (and) 02 may move. Next, when the tracked subject 01 moves to the left on the screen, it is basically the same as above, and in this case, the camera is moved. Move to the right on the screen and select the primary subject 0
2 may be captured.

When returning the tracking field of view to the initial position, if the subject is moving rapidly, first set the time setting circuit 2 in Fig. 1.
1. As explained with reference to the timer 22 and control signals a to d, etc., when the subject 01 moves out of the limit area BA, the movement detection circuit 5 and the gate movement circuit are temporarily activated by the control signal a from the calculation circuit 19. 6 is stopped, and the movement detection circuit 5 (for example, the memories 61 a and 6 l in FIG.
Clear the data that registered the characteristics of the subject stored in b), return the tracking field of view to the initial position after a certain period of time, and if there is a subject at this position that you intend to photograph, such as the next subject 02, it will be If the characteristics of the object are registered again and the tracking operation is performed based on this, stable tracking can be achieved.

Alternatively, even if the tracking field of view returns to the initial position, the photographer does not immediately register the characteristics of the subject and confirms that the next subject 02 has entered the initial position using the electronic viewfinder 14 etc. It is also possible to perform a tracking operation by registering the characteristics of the subject by operating the camera (for example, operating a button).

Furthermore, if the characteristics of the background or the target object are present at the position where the tracking field exists, the features are registered, and if the configuration is configured to update this registered value sequentially at the cycle of one field or several fields, the tracking field of view can be adjusted to the initial position. Even if the target subject does not exist at that position when the subject returns to the position, the tracking operation can be automatically and smoothly performed when the target subject enters the position or its vicinity. Note that the previous subject 01 may re-enter the initial position where the tracking field of view has returned before the subject 02, but in this case, the problem of updating the registration data of the subject's characteristics does not occur.

As mentioned above, when the tracked subject 01 moves out of the limit area BA and the movements of the movement detection circuit 5 and the gate movement circuit 6 are stopped, the timer 22 is activated during the period set by the time setting circuit 21. In response to the sent control signal C, the warning circuit 20 issues a warning by, for example, the above-mentioned means, and notifies the photographer that the tracked subject 01 has moved out of the limit area and that the tracking operation is currently stopped. When the control signal C ends, the tracking field of view returns to the initial position, the tracking operation resumes, and the warning circuit 20 stops operating. Note that, as described above, the entire photographing screen is regarded as the limit area instead of the limit area BA, and it is determined that the tracked subject has moved out of the photographing screen, and the above-mentioned tracking field of view is restored and the warning circuit 20 operates. It is also possible to perform various related operations described below.

Furthermore, as the warning circuit 20 operates, the display operation of the focus detection mark by the character generator 12 is stopped, and the operation of the lens drive device 17 is also stopped, and the focus detection state determined by the position of the lens group l at that time is stopped. Hold. Then, when the movement detection circuit 5 and the gate movement circuit 6 start the tracking operation again, the warning circuit 20
stops the operation, and the focus detection mark display operation and focus detection operation also restart. Note that as the gate position of the tracking gate circuit 4 moves, the gate position of the ranging gate circuit 7 also moves to the same related position, so naturally focus detection is performed on the subject at the position where the tracking field of view has moved. Furthermore, the relationship between the relative positions of the shooting screen or limit area BA and the tracked subject 01 in which the reset signal, etc. described above should be transmitted should be determined by considering various conditions. However, it is not limited to the relative positions shown in FIG. 11(B).

On the other hand, in the comparative example shown in FIG. 12, since the limit area is not set, the camera is panned to the right on the screen from the initial state shown in FIG. In the state shown in (C) of the same figure, where more time has passed after state B), the subject 01 has reached near the left edge of the screen, and it is thought that the photographer naturally intended to focus on it. Even if the next subject 02 to be photographed is in the center of the screen, complete focus detection cannot be performed on the subject 02, that is, a state of focus cannot be obtained.

FIG. 13 is a flowchart for explaining the main operations of the apparatus shown in FIG. ), the operating time of the timer 22 is set by manual operation of the time setting circuit 21 shown in FIG. 1 (step 81).

Next, the photographer sets a focus detection mark (FM in FIG. 11) at an initial position, for example, at the center of the photographing screen while looking at a display device such as the electronic viewfinder 14. At this time, the tracking field of view is also at its initial position (step 82). First, a tracking operation is performed on the subject 01 at the initial position, and the subject 01 is located on the shooting screen or in the limit area BA (hereinafter referred to as the 13th
In the figure and its explanation, the tracking operation continues as long as it is within the limit area (both are collectively referred to as the limit area) (steps 83 and 84).
. When the subject 01 moves out of the limit area, the timer 22 starts operating, the lens driving device 17 stops at that point, and is maintained in the focus detection state determined by the position of the lens group 1 at that point.

The warning circuit 20 also issues a warning (steps 85 to 87).
). Then, after a predetermined time set by the time setting circuit 21 has elapsed, the tracking field of view returns to the initial position, and when a new subject 02 enters the tracking field of view, the same operation as above is performed for this object. be exposed.

As a modification of the above flow, the subject 01 is in the limit area BA.
In an embodiment in which the tracking field of view is restored immediately after exiting, steps after step 86 are not necessary except for step 87. In this case, the time setting circuit 21 and timer 2 shown in FIG.
2 is omitted, and the control signal a from the arithmetic circuit 19 is input to the warning circuit 20, so that the warning circuit 20 issues a warning for a certain period of time.

(Effects) As described above, according to the present invention, there is provided a means for automatically tracking a subject within a shooting screen or a specific area thereof;
Since the camera is equipped with a means for notifying the user when the subject relatively moves out of the shooting screen or out of the specific area,
In a camera equipped with an automatic focus detection device, when a tracked subject moves away from the center of the shooting screen beyond a predetermined range, it is possible to notify the photographer of this fact or that the tracking operation is currently stopped. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of an embodiment of the camera of the present invention, and FIGS. 2 to 4 illustrate the limit area setting means in the embodiment of FIG. 1. Explanatory diagrams of the limit area, Figures 3 (A) and (B) are explanatory diagrams of the knobs and lock buttons for setting the boundary lines of the limit area in the X and Y directions of Figure 2, respectively, and Figure 4 ( a) to f) are explanatory diagrams for explaining the timing of the signal for setting the limit area, and FIGS. 5 to 8 are explanatory diagrams for explaining the subject movement detection means in the embodiment of FIG.
Figures (A) and (B) are explanatory diagrams showing the relationship between the divided tracking field of view and the subject image. 7 is an explanatory diagram showing a situation in which signals obtained from the device of FIG. 6 are plotted on a two-dimensional plane, FIG. 8 is a block diagram showing details of the movement detection circuit 5 in FIG. 1, and FIG. The figure is a block diagram showing details of the automatic focus detection device 8 in the diagram, and FIGS. 10(a) to 10e) are waveform diagrams for explaining the function of setting the focus detection mark in the embodiment of FIG. 11(A) to 11(C) are explanatory diagrams showing the relationship between a tracked subject and a focus detection mark thereto for explaining the function of the limit area in the embodiment of the present invention, and FIG. 12(A) Part C) is an explanatory diagram showing the relationship between the tracked subject and the focus detection mark in a comparative example in which no limit area is provided, FIG. 13 is a flowchart explaining the operation of the embodiment of FIG. 1, and FIG. 14 (A) and (B) are explanatory diagrams showing the relationship between the distance measurement field of view and the subject image in a conventional camera. Explanation of symbols 1: Lens group for focus adjustment, 2: Solid-state image sensor, which is an example of imaging means, 3: Signal processing circuit, 4: Tracking gate circuit, 5: Movement detection circuit, 6: Gate movement circuit, 7 : Distance measurement gate circuit, 8: Automatic focus detection device, lO: Synchronization signal generation circuit, 11: Gate pulse generation circuit, 12: Character sound generator, 13: Addition circuit, 14: Electronic viewfinder, 15: Encoder, 17: Lens drive device, 18: Limit area setting circuit, 19: Arithmetic circuit, 20:
Warning circuit, 212 time setting circuit, 22: timer, BA:
Limit area, FM: focus detection mark. Ka 2 figures, 3? Figure 3 (A) (B) Figure 4 Figure 5 Figure 6 Figure 7-Y Figure 8 Figure 9 Figure 10 ('b') n1ffi -------, nm (C ) 几goroshi 几goroshi 几-111111' (4) Burnt 111 and 11111 <6) Bar i
---------Ting Ding Fig. 11 Fig. 12 Fig. 14 Fig. 13

Claims (1)

[Claims] Means for automatically tracking a subject within a photographic screen or a specific area thereof, and a warning to that effect when the subject moves relatively outside the photographic screen or outside the specific area. A camera equipped with means and.