JPH065911B2 - camera - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a camera provided with an automatic tracking focus detection device, and particularly, when a subject being tracked moves away from a central portion of a shooting screen beyond a predetermined range, a moving image The present invention relates to a means capable of realizing a complicated screen configuration by a simple operation.

(Background Art) In a conventional camera including an automatic focus detection device with negligible difference, for example, a video camera, the distance measuring field of view is fixed at the center of the photographing screen as shown in FIG. As shown in (B), when a subject to be focused (hereinafter referred to as a focus detection target subject, a person in this example) moves, an object (a house in this example) located at a different distance from this subject is focused. However, the person as the focus detection target object is blurred, so that the focus detection target object must always be placed in the center of the screen due to the screen configuration. Therefore, although means for varying the distance measuring visual field position have also been proposed, these means change the distance measuring visual field position by the photographer by operating a knob or the like, and when a subject moves during photographing, It is difficult to always maintain the distance measuring visual field position on the focus detection target object by these knobs.

In order to solve the above drawbacks, the present applicant first sets a movable tracking field of view, extracts the feature of the object to be measured with respect to this tracking field of view, and stores the extracted feature,
The presence or absence of movement of the object is detected based on the stored characteristics and the newly extracted characteristics of the object to be measured, and the distance measuring field is tracked to the movement of the object according to the relative movement of the object. We have proposed an automatic tracking focus detection device that can be moved (Japanese Patent Application No. S59-105897). It is desirable to take measures that can realize a complicated screen structure of a moving image by a simple operation even when the user moves away from the target.

(Object) Therefore, the present invention solves the above-mentioned drawbacks of a camera having a conventional automatic focus detection device, automatically detects the moving position of a moving subject, and tracks the distance measuring field of view with the movement of the subject. When moving a subject to perform focus detection or focus adjustment, even if the subject being tracked moves away from the central part of the shooting screen by more than a predetermined range, a complicated screen configuration of the moving image can be realized by a simple operation. It is an object of the present invention to provide a camera equipped with a means capable of doing so.

More specifically, this invention provides a new subject (when the original subject that has once moved away returns to the screen again when the subject being tracked moves away from the center of the shooting screen by more than a predetermined range. The same applies to the following), and when a new subject comes into a predetermined position on the screen, the camera is equipped with a means capable of automatically tracking the subject appropriately. The purpose is to provide.

(Explanation by Embodiments) Means taken in the present invention for achieving the above object will be exemplified and described below with reference to FIGS. 1 to 13. The following description is an overall description of the embodiment of the camera according to the present invention regarding an example of extracting the characteristics of the tracked subject by color signal information, and the limit area setting means, the subject movement detecting means, and the automatic focus detecting means in the same embodiment. And the focal length adjusting means, and the operation and operating method of the same embodiment.

(Overall Description of Embodiment of Camera According to This Invention) (First
FIG. 1 shows a main part of an embodiment of a camera according to the present invention. In the drawing, reference numeral 1 denotes a lens group for focus adjustment in a photographing lens, which is usually a lens barrel (not shown). A helicoid is fitted to and the position is changed back and forth by the rotation operation of the lens barrel. Reference numeral 2 denotes a lens group (for example, a zoom lens) for changing the focal length, which is composed of a variable power lens and a correction lens, and in many cases the position is changed according to a cam (not shown) to change the focal length. Let 3 more
Is an imaging system lens group for correctly forming an image of an object at a shooting distance determined by the position of the lens group 1 for focus adjustment at a predetermined position. C. 4 is an example of an image pickup means. C. D. A solid-state image pickup device such as the image pickup device drive circuit 5 provided on the image forming surface of the lens group 3.
The light from the subject that is driven by and enters the light receiving surface is photoelectrically converted. The image pickup device drive circuit 5 is controlled by a clock pulse generated by the clock generation circuit 6 or a signal obtained by dividing the clock pulse. M ₁ is a focus adjustment (AF) motor that is linked to the lens barrel holding the lens group 1, and M ₂ is a zoom motor that is linked to a cam (not shown) for moving the lens group 2. Since the configurations and functions of the above-mentioned respective parts are well known, detailed description thereof will be omitted.

Reference numeral 7 denotes a signal processing circuit. The time-series signal photoelectrically converted by the image pickup device 4 is subjected to processing such as blanking correction and gamma correction in the same circuit 7, and a color difference signal (R- Y) and (B-Y) and luminance signal Y
Is created. These color difference signal and luminance signal are combined with the sync signal generated by the sync signal generation circuit 10 in an encoder (not shown), and are output video signals, for example, NT.
An SC signal is formed, and this NTSC signal is supplied to a utilization device, for example, a VCR. In the following explanation,
It is assumed that the output video signal is an NTSC signal.

The color difference signals (RY) and (BY), and the luminance signal Y if necessary, are input to the subject movement detection circuit 9 via the tracking gate circuit 8 and the movement direction of the subject or The amount of movement is detected. Here, since the movement between the subject and the camera is relative, the above-mentioned movement of the subject means not only the case where the camera is fixed and the subject moves,
This refers to the case where the subject stops and the camera moves or both move, and the present invention is applicable to any of the above cases. Reference numeral 10 is a synchronizing signal generating circuit, which is controlled by a clock pulse generated by the clock generating circuit 6 or a signal obtained by dividing the frequency of the clock pulse. Reference numeral 11 denotes a gate pulse generation circuit, which is synchronously controlled by a horizontal synchronization signal and a vertical synchronization signal generated by the synchronization signal generation circuit 10 and is controlled by a microprocessor 16 described later to control a tracking gate circuit 8 and a distance measurement gate circuit described later. Generate a gate pulse for 12.

In the tracking gate circuit 8, the gate position for the color difference signal is set by the gate pulse generated by the gate pulse generation circuit 11. By this, the characteristics of the subject,
Further, the position of the tracking visual field for extracting the background feature is determined, for example, in the manner shown in FIGS. 5 to 9 described later.
In other words, the range of the color difference signal or the like to be input to the movement detection circuit 9 is determined, and the movement of the subject is detected by the change in this signal. This subject movement detection signal is input to the microprocessor 16, and a signal (for example, a signal indicating a movement direction) for moving the gate position of the tracking gate circuit 8, that is, the tracking visual field position according to the movement of the tracked subject is generated. To be done. This signal is supplied to the gate pulse generation circuit 11 to form a gate pulse for extracting the color difference signal at the position corresponding to the movement of the tracked subject.

On the other hand, the luminance signal Y is input to the automatic focus detection circuit 13 via the distance measurement gate circuit 12, and the focus detection or focus adjustment signal is generated in the same circuit. In the distance measuring gate circuit 12, the gate position with respect to the luminance signal Y is set by the gate pulse generated by the gate pulse generating circuit 11 to the same relational position as that of the tracking gate during the tracking operation. A range (hereinafter referred to as a distance measuring field) input to the automatic focus detection circuit 13 for detecting the focus of the subject is determined. In the embodiment of the present invention, the tracking field of view and / or the distance measuring field of view can be displayed on a display device such as an electronic viewfinder as necessary, but this is not an essential means.

Although the tracking gate circuit 8 and the distance measuring gate circuit 12 are separately provided in FIG. 1, both gate circuits may be provided in common, or the tracking field of view set by the former by connecting the latter to the latter stage of the former. It is also possible to use a portion of a smaller range within the distance measuring field for focus detection. However, in either case, the tracking field of view and the distance measuring field of view must be set at the same relational position with respect to the moving subject. In the example shown in FIG. 1, the sizes of the tracking field of view and the distance measuring field of view can be set arbitrarily.

Further, according to the outputs of the position sensor P ₁ for detecting the absolute position of the lens group 1 for focus adjustment and the position sensor P ₂ for detecting the absolute position of the lens group 2 for changing the focal length, the tracking visual field size is increased. The size determining circuit 14 can adjust the size of one or both of the fields of view to the optimum size for the subject regardless of changes in the subject shooting distance and the lens focal length.

An automatic focus detection circuit 13 is provided after the distance measurement gate circuit 12.
Is connected, automatic focus detection is performed according to known means, and the output signal controls the AF motor drive device 15,
The lens group 1 is driven by the AF motor M ₁ . When the in-focus point is detected, the above control loop 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 microprocessor 16 receives the clock pulse from the clock generation circuit 6, the subject movement detection signal from the subject movement detection circuit 9, and the signal for determining the size of the tracking visual field or the distance measuring visual field from the tracking visual field size determining circuit 14. Besides, focal length information set by a photographer according to a limit region setting signal from a limit region setting circuit 17 and a time setting signal from a time setting circuit 18, and a shooting distance from an input terminal I ₁ , and an input terminal I _{2 which will be described later.} Tracking field-of-view position setting information from the tracking gate circuit 8,
The subject movement detection circuit 9, the gate pulse generation circuit 11, the distance measurement gate circuit 12, the AF motor drive device 15, the zoom motor drive device 19 and the character generator 20, which will be described later, are controlled.

Next, the tracking visual field returning means in the embodiment of FIG. 1 will be described. The limit area setting circuit 17 cooperates with the microprocessor 16 to exemplify a main component part for returning the tracking field of view to the position within the screen when the subject goes out of the photographing screen or out of the specific region thereof. It is controlled by the horizontal synchronizing signal and the vertical synchronizing signal generated by the synchronizing signal generating circuit 10 and is a specific area in accordance with a signal input from the input terminal I _{3 according} to the setting of the photographer, for example, BA in FIG. Set the limit area indicated by. The limit area BA is provided only for the purpose of performing a tracking operation only inside the limit area BA, and the current position of the tracking field of view is previously set according to the output signals of the limit area setting circuit 17 and the movement detection circuit 9 in the microprocessor 16. It is determined whether or not it is within the manually set limit area BA. Next, a means for returning the tracking field of view to the standby position when it is determined that the position of the tracking field of view, that is, the position of the tracked subject on the screen has left the limit area BA will be described. 16 or the subject movement detection circuit 9 to transfer the control signal a to reset the circuit, and the gate pulse generation circuit 11 to receive the control signal c.
By transferring the control signal d to the tracking gate circuit 8 and moving the gate position of the tracking gate circuit 8 to a position which can be set within the photographing screen, for example, a position corresponding to the standby position shown by TFh in FIG. 13 (h). is there. As a result, the tracking field of view moves to, for example, the above-described standby position, and shifts to the tracking mode for the subject that is expected to enter the shooting screen next.

The tracking visual field returning means described above does not perform the return to the standby position immediately after the subject exits the limit area BA, in order to stably perform the tracking operation when the subject moves rapidly. It may be performed after a possible predetermined time. The time setting circuit 18 is provided for that purpose, and the circuit sets the above-mentioned predetermined time based on the timer time information input by the setting of the photographer. When it is determined that the tracked subject has left the limit area BA, the microprocessor 16 transfers the control signal a ′ to the movement detection circuit 9 to stop its operation, and the control signal b to the character generator described later. 20 and the AF motor drive device 15 to stop the display operation of the focus detection mark in the former case, and to stop the drive device 15 in the latter case so as to maintain the focus detection state determined by the position of the lens group 1 at that time. To do. Further, the control signal b may be transferred to a warning circuit (not shown) to warn the photographer that the tracked subject has moved out of the limit area BA or that the tracking operation is currently stopped. Good. As a means for that, the boundary line (frame) of the limit area described later.
It is conceivable to use means such as flashing of the above or generation of an audible sound signal.

In the above, the character generator 20 receives the position information of the tracked subject from the microprocessor 16 to form the focus detection mark signal, and adds this signal and the output video signal in the adder circuit 21 to add an electronic viewfinder (EVF). ) 22 and the like, and displays a mark indicating the subject for focus detection in addition to the video signal. The focus detection mark signal forming means is, for example, Japanese Patent Application No. 59-82 filed by the present applicant.
No. 709, the title of the invention "distance measuring visual field selection device" can be used.

When the predetermined time set by the time setting circuit 18 has passed, the gate pulse generation circuit 11 and the tracking gate circuit 8 are respectively controlled by the control signals c and d from the microprocessor 16.
The tracking gate circuit 8 returns the gate position of the tracking gate circuit 8 to the position corresponding to the standby position, the tracking field of view moves to the standby position, the movement detection circuit 9 starts the subject movement detection operation again, and the control signal character by the end of b
The generator 20 and the AF motor drive device 15 restart their operations, the warning circuit stops their operations, and the automatic tracking mode is restarted.

In the above-mentioned embodiment, the limit area is a means for defining the range in which the tracking operation is performed, and does not necessarily need to be displayed on the finder or the like. Further, the limit area is usually set as a range narrower than the entire area of the shooting screen or as a narrower range within a partial area of the shooting screen. However, when the limit area setting circuit 17 sets the entire shooting screen as the limit area by the operation of the photographer, or when the entire shooting screen is fixedly set as the limit area, the tracked subject moves outside the shooting screen. It is judged that the tracking visual field has been returned, and the tracking field of view and the operation related thereto are performed. Further, in this specification, the meaning of the term "the subject goes out of the photographing screen or out of the limit area" will be described later with reference to FIG.

Regarding the distance measuring field returning means in the embodiment of FIG.
During the tracking operation, as described above, the gate position of the distance measuring gate circuit 12 follows the movement of the subject and moves to the same position as the gate position of the tracking gate circuit 8, and therefore the distance measuring field of view has the same relationship as the tracking field of view. When the subject moves out of the shooting screen or out of the limit area of the shooting screen, the distance measuring field of view is returned to, for example, the center part of the shooting screen or the corresponding position of the tracking field of view to return to the standby position. Return to the vicinity.
For that purpose, the microprocessor 16 transfers the control signal c ′ to the gate pulse generating circuit 11 and the control signal e to the distance measuring gate circuit 12 so that the gate position of the distance measuring gate circuit 12 is set at the center of the photographing screen or in the vicinity thereof. It can be moved to a considerable position.

(Limit Area Setting Means in the Embodiment of the Invention) (First
(Fig. 4) Next, the limit region setting means in the embodiment of the present invention will be described with reference also to Figs. In FIG. 2, reference numerals 30 and 31 denote the boundaries of the limit area BA in the x direction.
Similarly, reference numerals 2 and 33 indicate boundaries in the y direction, and the boundaries 30 and 31 for defining the position in the x direction are moved to the left and right by the manual operation of the knob 40 in FIG. The position is fixed by the operation of. 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. 7B, and the position is fixed by operating the lock button 43. That is, the position of the limit area BA can be variably set by operating the knobs 40 and 42, but one more knob is provided in each of the x direction and the y direction so that the boundary lines 30 and 31 and the boundary lines 32 and 33 are independent. The size of the limit area BA may be set to be variable.

Boundary line 3 according to the operation of the above knob and lock button
In order to generate the signals indicating the positions of 0 to 33, the positions of the horizontal scanning lines corresponding to these boundary lines (corresponding to 32 and 33) and the horizontal scanning lines having these horizontal scanning lines as the upper and lower ends. A specific position (corresponding to 30, 31) may be selected. For that purpose, the number of horizontal scanning lines in one field is counted for the former, the number of horizontal scanning lines corresponding to the positions of the boundary lines 32 and 33 set by the knob 42 or the like is selected, and for the latter, the horizontal scanning lines are selected. A pulse train may be generated by multiplying the frequency of the synchronizing signal, counting from the starting end of each horizontal scanning cycle, and selecting a pulse having a number corresponding to the position of the boundary lines 30 and 31 set by the knob 40 or the like. Alternatively, triangular waves that are respectively synchronized with the horizontal synchronizing signal and the vertical synchronizing signal are generated, and these triangular waves correspond to the positions of the boundary lines (30, 31) and (32, 33) set by the knobs 40 and 42, etc., respectively. To generate rectangular waves, and to generate a pair of pulses corresponding to the front end and the rear end of these rectangular waves, and to generate logic waves of one rectangular wave and the other pair of pulses, respectively. It is sufficient to take the sum (Japanese Patent Application Laid-Open No. 59-4384, which is the application of the present applicant, and the title of the invention is "video camera"
reference).

FIG. 4 shows the timing relationship of the signals created as described above for one horizontal scanning period.
(A) shows the video signal in a simplified manner, (b) shows the limit region, and more specifically shows the position where the boundary lines 30 and 31 of FIG. 2 intersect the horizontal scanning line, and (c) shows ( A composite signal of the a) signal and the (b) signal, (d) the limit region width in the x direction (defined by the boundary lines 30 and 31) of FIG.
(E) shows the gate position by the tracking gate circuit of FIG.
(F) shows a time axis. In this example, the signal indicating the width of the limit region in (d) has a low level in the limit region and a high level in the other parts. Further, the position of the tracking visual field is determined by the signal (e) indicating the gate position. Note that FIG. 4 does not show a signal indicating the limit region in the y direction of FIG. 2, but this limit region is also set in the same manner as that shown in FIG. The above-mentioned limit area BA does not necessarily need to be displayed on the display device, but in order to display this on the display device such as the electronic viewfinder 22, the output signal of the limit area setting circuit 17 is set to the character generator 20 or directly. It may be supplied to the electronic viewfinder 22 and displayed.

In the microprocessor 16, in order to determine whether the gate position by the tracking gate circuit 8, that is, the tracking field of view exists within the limit area BA, the signal (e) in FIG.
On the time axis, or by examining the temporal relationship between the signal (d) and the signal (e). That is, in the former case, it is assumed that the tracked subject, in other words, the signal indicating the gate position moves from right to left in FIG. 4 (T ₂ −
T ₁ ) <T _K , or moving from left to right (T ₄ −
It is performed by the microprocessor 16 calculating whether or not the relationship of T ₃ ) <T _K (where T _K is a positive constant defined by design) is satisfied. Note the position of generally the limit region BA of the tracking field can be known by calculating the _{(T 2 -T 1) / (} T 4 -T 1). In the latter case, if the logical sum of the signal (d) and the signal (e) is low level, it is determined to be inside the limit area BA, and if it is high level, it is determined to be outside the limit area BA.

The tracking field of view is outside the limit area BA, or the limit area BA
When it is determined that the movement is from the central portion to the outside of the area and is within a certain range (for example, T _K ) with respect to the boundary line, the microprocessor 16 instructs the movement detection circuit 9 to perform the above-mentioned control. The signal a is sent, and the tracking visual field returning operation is performed thereby.

In this specification, the term "the subject goes out of the photographing screen or outside the limit region" means that the subject relatively goes out of these, or the subject moves from the center of the photographing screen to the vicinity of these boundaries. Moving to the above (T ₂ −T ₁ )
_{<T K} or _{(T 4} -T 3) <refers to the case where so satisfy the relationship of _{T K.}

(Subject movement detecting means in the embodiment of the present invention) (FIGS. 1 and 5 to 9) Next, the movement of the tracked subject is detected, and the movement is tracked to the tracking gate circuit 8 in FIG. A specific example of the movement detection circuit 9 for moving the gate position, that is, the tracking field of view according to FIG. 5 will be described with reference to FIGS. The following specific example is an example in which the characteristics of the tracked subject are extracted as color signal information, but the characteristics of the subject are also extracted from the luminance signal, and information such as the shape of the subject, the temperature, or the characteristic contrast in the subject. You can also use

To summarize the subject movement detection and automatic tracking means below,
Some parameter representing the characteristics of the subject, in this example the colors of the subject and the background, is extracted with respect to the tracking field of view set by the tracking means, the extracted features are stored, and the stored features are newly extracted. The presence or absence of the movement of the subject based on the characteristics of the subject, and the moving direction or the moving position of the subject when detected,
The tracking field of view is moved along with the movement of the subject, and the distance measuring field of view is moved in the same positional relationship as the tracking field of view is moved.

The tracking field of view has a two-dimensional spread in principle, but here, in order to simplify the explanation, it is shown in FIG. 5 (A).
It is assumed that the tracking field of view has a one-dimensional expansion extending in the horizontal direction as shown in FIG. The tracking field of view is A, B,
It is assumed that it is divided into three parts C (hereinafter, each part is referred to as a pixel). In order to form a two-dimensional tracking visual field, for example, pixels B or A, B and C shown in FIG.

As shown in FIG. 6, the color difference signals (RY) and (BY) obtained as time-series signals from the respective pixels are respectively integrated circuits 50a and 50b and a sample hold (S / H) circuit, as shown in FIG. 51a, 51b and A / D conversion circuit 52
a, 52b, integration, sample hold and A / D
After performing each conversion process, the memories 53a and 53b are respectively processed.
To memorize. When the stored values are plotted on the (RY) and (BY) Cartesian coordinates for each pixel A, B and C, they are displayed as shown in FIG. 7, for example. In the figure, points A ₀ , B ₀ and C ₀ respectively represent the signals extracted from the pixels A, B and C in FIG. 5 (A). Here, a signal representing only, for example, clothes of the person who is the subject is output from the pixel B, and signals from the pixels A and C are output.
It is assumed that signals obtained by adding signals representing the clothes of the subject and the background are extracted. Furthermore, in the figure, it is assumed that the background color is different between the left side and the right side of the subject. Therefore, the points A ₀ and C ₀ have different positions on the color difference signal coordinates.

Next, when the subject shown in FIG. 5 (A) moves to the right in the screen as shown in FIG. 5 (B), the ratio of the subject to the background in pixels A and C changes, and The signals obtained from A and C change as shown in FIG. 7, A ₁ and C ₁ , respectively. On the other hand, since the pixel B remains in the subject as shown in FIG. 5B, the signal obtained from the pixel B hardly changes if the clothes are almost monochromatic. Therefore, here, for simplification, B ₁ = B ₀ . In this case, as shown in FIG. 7, the point C ₁ approaches the point B ₀ (= B ₁ ) and the point A ₁ changes to the point B ₀ (=
B ₁ ), the line segment B ₁ C ₁ becomes a line segment B ₀ C _0.
It becomes smaller, and the line segment A ₁ B ₁ becomes larger than the line segment A ₀ B ₀ . On the contrary, when the line segment B ₁ C ₁ is larger than the line segment B ₀ C ₀ and the line segment A ₁ B ₁ is smaller than the line segment A ₀ B ₀ , the subject is leftward in FIG. 5 (B). You have moved to. 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 FIG. 5 (B) on the screen, the point A ₁ is on the extension of the line segment A ₀ B ₀ . The point C ₁ will occupy a position on the line segment B ₀ C ₀ . The present invention can be applied to either of the above cases.

In order to detect the movement of the tracked subject using the above-mentioned phenomenon, for example, a change in the length of the line segments AB and BC may be detected. For that purpose, the color detection circuit in the movement detection circuit 9 detects the color of the object with respect to the pixels A, B, and C, and stores this in the memory in the movement detection circuit 9 via, for example, a manual mechanical input means. The signal representing the color of the subject newly extracted at the next time is compared with the signal stored in the memory, and whether or not the subject has moved and the subject has moved. In this case, for example, the moving direction is detected. The above processing is performed according to the average value during 1/60 second which is a period of one field of the television signal or during the period of several fields. Hereinafter, it will be described that both are processed collectively in one field period.

FIG. 8 shows an example of a specific circuit for executing the above processing, and this circuit also shows the details of the movement detection circuit 9 in FIG. In the figure, 60 is the distance between the signals An and Bn (FIG. 7 shows the case where n = 1) obtained from the pixels A and B when the subject moves within the screen, that is, the length of the line segment AnBn. _Sa D _An. Change in _Bn ,
The length of the line segment _A 0 _{B 0} of the specifically _{D A0.} Ratio with _B0 D _{An. Bn} / D _{A0. B0} shows an apparatus for comparing the threshold value K _A with the threshold value K _A , where 61 is the length D _{Cn. Bn} and the length of the segment C ₀ B ₀ D _C0. Ratio with _B0 D _{Cn. Bn} / D _{C0. 3} shows a device for comparing _B0 with a threshold K _C.

Values on the coordinates of points A and B representing the color characteristics of pixels A and B on the (RY) and (BY) Cartesian coordinates are stored in the memory 63 when the switch 62 is turned on by the initial setting. To be done. That is, the value stored in the memory 63 is _{A 0} for pixels A, for the pixels B is _{B 0.} Note that the above-mentioned initial setting, that is, the registration of the reference value for tracking, is performed by a color designation circuit provided specially as described later with reference to FIG. 9, instead of the video signal obtained by photoelectrically converting the light from the subject. Alternatively, a reference color plate of a color corresponding to the color of the subject may be arranged in front of the image pickup optical system at the time of initial setting and the color may be stored in the memory 63.

On the other hand, after the scanning line scanning in the case of n = 0, approximately n / 60
(R−Y), (B− of An and Bn obtained every second
Y) The value on the Cartesian coordinates is directly transferred to the distance calculation circuit 64. Therefore, the information of each point of A ₀ , B ₀ and An, Bn is taken into the distance calculation circuit 64, and D _{A0. B0} and D _An. The value of _Bn is calculated from the difference between the positions of the (RY) and (BY) coordinates of these points. Based on these values, the divider 65 outputs D _{An. Bn} / D _{A0. B0} is calculated and compared with the threshold value K _A set by the threshold value setter 66 in the comparison circuit 67. And the threshold value K _A
When there is a change exceeding 1, the movement determination circuit 68 outputs "1". Similarly, in the comparison device 61, D _{Cn. Bn} / D _{C0. B0} is calculated, and if there is a change exceeding the threshold value K _C , “1” is output to the movement determination circuit 68. In many cases, the timings when the switch 62 is turned on in the comparison devices 60 and 61 are substantially the same time, and K _A = K _C.

Now, the points (RY) representing the color characteristics of pixels A, B, and C,
(BY) Assuming that the moving situation on the Cartesian coordinates is the situation shown in FIG _{. Bn} / D _{A0. B0} and D _{Cn. Bn} / D _C0. When obtaining the _B0 specific values of, in this case, n = _{1, B} 0 =
B ₁ and K _A = K _C = 2 and D _{A1. B1} / D _{A0. B0} = 2.2, D _{C1. B1} / D _{C0. Since B0} = 0.36, only the comparison circuit 67 in the comparison device 60 outputs "1" to the movement determination circuit 68. In this case, the movement determination circuit 6
8 sets the tracking gate setting timing for a predetermined time (for example, NT
In the case of the SC system, a signal that delays by 1/125 of one horizontal scanning period) is output to the microprocessor 16, whereby the microprocessor 16 controls the gate pulse generation circuit 11 and the tracking gate circuit 8 to change the tracking field of view of the subject. It is moved in the moving direction, that is, rightward in the screen of FIG. 5 (B). On the other hand, when only the corresponding comparison circuit in the comparison device 61 outputs “1” to the movement determination circuit,
The movement determination circuit 68 outputs a signal that advances the tracking gate setting timing by the above-described predetermined time, and moves the tracking field of view to the left in the screen of FIG. 5 (B).

In this way, D _{An. Bn} / D _{A0. B0} exceeds the threshold K _A , or D _{Cn. Bn} / D _{C0. The} movement determination circuit 68 outputs a signal for delaying or advancing the tracking gate setting timing by, for example, the above-described predetermined time depending on whether _B0 exceeds the threshold value K _C, and the microprocessor 16 responds to this signal by the gate pulse generating circuit. By controlling 11 and the tracking gate circuit 8 and further the distance measuring gate circuit 12, the tracking field of view and the distance measuring field of view can be moved following the movement of the subject, and focus detection can be performed at that position.

As a modification of the subject movement detection means described above, for pixel B, B ₀ , which is information at the stage of initial setting (registration) of the feature of the subject, is used instead of the information Bn based on the marking position based on the movement, and D _{An. Bn} and D
_Cn. Instead of _Bn , D _{An. B0} and D
_Cn. If the movement is detected by _B0 , tracking can be performed without malfunction even when the subject moves at high speed.

As a means for performing the initial setting (registration) of the feature (color) of the subject in the subject movement detection, when the color of the subject can be detected in advance or can be predicted,
The initial setting (registration) of the characteristics of the subject can be performed by the color designating circuit. FIG. 9 shows an example of the structure for that purpose. The color difference signal in the video signal is inputted to the color detection circuit 9a through the tracking gate circuit 8 and the detected color feature is changed in the movement determination circuit 9b. The signal is compared with the initial setting value designated by the designating circuit 23, and a signal representing the determination result is transferred to the microprocessor 16. If the switch 62 of FIG. 8 is configured to switch between the output signal of the signal processing circuit 7 and the output signal of the color designating circuit 23 of FIG. 1 and input them to the memory 63, these signals can be output as necessary. Either way, the initial settings can be made. Further, in FIG. 8, the movement judgment circuit 68 is provided only when there is a change exceeding the threshold value set by the threshold value setter 66 or the like.
The reason why "1" is output is for the purpose of performing a stable tracking operation without causing hunting or overshoot.

(Automatic focus detection means in the embodiment of the present invention) (First
The automatic focus detection circuit 13 of FIG. 1 can utilize known means. As an example, a method of performing focus detection by a high frequency component in a luminance signal (for example, “N”) is used.
HK Technology Research "Vol. 17 No. 1 (Vol. 86 No.) Showa 4
Issued in Year 0, page 21 "Refer to" Automatic focus adjustment of television camera by hill climbing servo system "" will be described. In FIG. 10, reference numeral 70 is a band filter, 71 is a level detection circuit, and 72 is a focusing direction detection circuit. The contour component, that is, the high frequency component is band-passed from the output luminance signal of the distance measurement gate circuit 12 of FIG. The level is detected by the filter 70, the level of this high frequency component is detected by the level detection circuit 71, and the focusing direction detection circuit 72 controls so that this detection level becomes maximum,
A signal representing the moving direction for focus detection is output from the focusing direction detection circuit 72 to the AF motor drive device 15.

In carrying out the present invention, means for focus detection is not limited to the above-mentioned means and may be any known means such as infrared ray T.
TL focus detection means or the like can be used.

(Focal Length Adjusting Means in Embodiment of the Invention) (First
(FIG. 11, FIG. 11) In the embodiment of the present invention shown in FIG.
It is configured to change the focal length of the. 11th
The figure explains the mode of change of the focal length, and x ₁ x ₂ in the figure shows the length of one side of the limit area BA in the x-axis direction in FIG. Now, assuming that the tracked subject enters the limit area BA from the right side in FIG. 11 and goes out of the same area on the left side, the position of the subject in the same area is (T ₂ −T ₁ ) in FIG. This can be found by calculating / (T ₄ −T ₁ ), and the microprocessor 16 transfers a control signal to the zoom motor driving device 19 to drive the zoom motor M ₂ according to this value, and the lens group 2 Is moved to change its focal length according to the pattern shown in FIG. 11, for example. In this example, the longest focal length is obtained when the subject is almost in the center of the limit area BA. Further when the tracking field is substantially coincident with the left edge of the limit region BA, i.e. above the example described in relation to FIG. 4 (T 2 _-T 1) _<time adapted to satisfy the relationship of T _K, lens If the focal length of 2 is changed to the shorter focal length side, the subject seems to be fixed at the same position, and the tracking operation range can be effectively widened. In order to simply widen the tracking operation range, the lens group 2 may be adjusted to have a short focal length from the right end x ₁ to the left end x ₂ of the limit area BA.
The reason why the lens group 2 has a long focal length in the central portion of A is to make the focal length reach the purpose of photography.

(Operation and operation method of the embodiment of the present invention) (FIGS. 1, 12, and 13) Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described. The following description will be given mainly with reference to FIGS. 12 and 13 for an example of the operating method of the same embodiment. In this example, it is assumed that the subject is framed out and shooting is started with the tracking field of view at the standby position. The setting of the tracking visual field position is performed based on the information input to the microprocessor 16 from the input terminal I _{2 of} FIG. 1 by the manual setting of the photographer. Specific means therefor may be based on the limit region setting means described in FIGS. 2 to 4. In this example, the tracking visual field is variably set in size by the tracking visual field size determination circuit 14 in FIG. In FIG. 13A, the tracking visual field position during standby is TF.
It is indicated by a. On the other hand, in the standby state, the distance measuring field FFa
Is, for example, in the center of the screen frame FR of the electronic viewfinder 22, and its size is assumed to be constant throughout all steps in this example. The setting of the limit area BA is performed by the means described with reference to FIGS. 2 to 4 based on the information input to the limit area setting circuit 17 from the input terminal I _{3 of} FIG. 1 by manual setting by the photographer. .

The tracking operation shown in the flowchart of FIG. 12 is performed according to the principle described with reference to FIGS. 5 to 9 in principle, and the initial setting of the reference color of the object for tracking is performed by the photographer's operation. This is performed through the color designating circuit 23 shown in FIG. Further, in the normal tracking operation, it is assumed that the pixel B in FIG. 5 is included in the subject.

In step 81 of FIG. 12, first, B ₀ is designated as a reference color representing the feature of the subject by the operation of the photographer, and this value is taken in. At this stage, the initial values (A ₀ and C ₀ ) for the pixels A and C are not incorporated. The reason for this is that if the background color at the time of setting the angle of view and starting shooting and the background color at the time of capturing B ₀ are different, a malfunction may occur at the start of tracking. Next, by the photographer's operation, the initial position of the tracking field of view (standby position TFa)
Is set (step 82), and thereafter, the tracking field of view waits at that position until a subject enters the tracking field of view. Then, at the standby position TFa, the absolute value of the difference between the value B taken in from the pixel B (corresponding to the background color at this standby position until the subject comes in) and the above B ₀ | B−B
₀ | is calculated (step 83), the result is compared with a predetermined dead band width ΔB (step 84), and this operation is repeated until the relationship of | B−B ₀ | <ΔB is established. That is, the tracking visual field continuously checks that the subject is coming into the same position at the standby position TFa.

When the relationship of | B−B ₀ | <ΔB is satisfied, it is determined that the subject has entered the standby position TFa, and the distance measuring field of view is first
As shown by FFb in FIG. 3B, the tracking visual field position TFb,
That is, it moves to the subject position (step 85). Further, in order to start the tracking operation, colors A ₀ and C ₀ representative of the characteristics of the background (including a part of the subject) are designated (step 8).
6), (R-Y), (B-Y) coordinates on the line segment A ₀ B ₀ length D _{A0. B0} and the length of the segment C ₀ B ₀ D _{C0. B0} and _B0 are calculated (step 87).

When | B−B ₀ | <ΔB is determined here, for example, 1/60 seconds later, A ₀ and C ₀ are designated in the next field, and the tracking operation is started from the next field. In step 88, the substantial tracking mode is started. Therefore, when the subject being tracked goes out of the limit area BA, the apparatus is put in a standby state for a new subject, and after confirming that the new subject has come to the standby position in the screen, Since the distance measuring field of view is moved to the subject position and the tracking mode is restarted for this subject, moving image shooting can be performed by a simple operation.

In the above example, the color information of each pixel A, B, and C one frame after is determined in step 88 after the determination in step 84 is YES. For the case where the subject has gone out of the screen again, it is further examined whether or not the relationship of | B−B ₀ | <ΔB is satisfied (step 89), and if this relationship is not satisfied, the tracking field of view is restored again. The distance measuring field of view is returned to the standby position and to the initial position again (steps 97, 98, first).
Figure 3 (h)).

As long as | B−B ₀ | <ΔB, the tracking operation proceeds (steps 90 to 92), and if the subject is in the plane of the limit area BA, the focus of the lens group 2 in FIG. 1 is followed according to the pattern shown in FIG. The distance is adjusted (steps 93 and 94). FIGS. 13 (c) to 13 (e) show this situation, in which the longest focal length is obtained at the position shown in FIG. 13 (d), and then the short focal length is again set as the object moves to the left in FIGS. 11 and 13. It is facing (Fig. 13 (e)). And TFf of the same figure (f)
As shown in FIG.
When it reaches the end of A, the focal length of the lens group 2 is adjusted to a shorter focal length, that is, the angle of view is increased to the wide end (step 95). By further widening the angle of view, the subject seems to be fixed at that position as shown in FIG. 9G, effectively expanding the tracking range. Then, the focal length of the lens group 2 reaches the wide end (the shortest focal length in the lens group 2), and the subject is in the limit region B.
When the vehicle exits A, the tracking field of view returns to the standby position TFh in FIG. 13 (h), and the range finding field also returns to the initial position FFh.
The device goes into standby. In this state, the operation may be redone from the designation of B ₀ for a new subject.

In the above description, that the subject leaves the limit area BA has the same meaning as described with reference to FIG. 4, and the same operation as described above may be applied by regarding the entire photographing screen as the limit area. it can. Furthermore, the movement of the subject means the relative movement between the subject and the camera as described above.

The above operating method shows an example of the operating method of the camera of the present invention, and the operating method is not limited to the above. Further, in the above description, the position of the subject can be detected by the color information as well as other information representing the features of the subject described above. The waiting position of the tracking field of view is the 13th
In addition to the position shown in the figure, it can be set to any position on the screen according to the photographer's intention of drawing.

(Effect) As described above, according to the present invention, in the automatic tracking device that detects the movement of the subject to be tracked and tracks the subject in the specific region in the shooting screen, Tracking area setting means for setting a tracking area for tracking the tracking object, and a characteristic of the tracking object is extracted from an image pickup signal corresponding to the tracking area, and based on a change in the characteristic, Automatic tracking means for controlling the tracking area setting means to change the setting position of the tracking area within the specific area; and subject tracking of the automatic tracking means when it is determined that the tracking area has left the specific area. Returning means for stopping the operation and returning the tracking area to a predetermined standby position in the photographing screen, and a preset target at the standby position. Comparing the information representing the feature of the image and the information extracted from the tracking area, when the comparison result is within a predetermined dead zone width, the determination means for determining that the subject is present at the standby position, Since the determination means includes a control means for restarting the automatic tracking operation of the automatic tracking means when the presence of the object at the standby position is detected, the tracking object is moved outside the photographing screen or outside the specific area. In this case, you can put the device in a standby state for a new subject, and when the new subject comes into a specific position on the screen, perform appropriate automatic tracking for that subject. Even if the subject inside goes out of the shooting screen or goes out of the specific area, depending on the photographer's intention of drawing,
Therefore, it is possible to realize a difficult moving image shooting with a simple operation.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential part of an embodiment of the camera of the present invention, and FIGS. 2 to 4 are diagrams for explaining the limit area setting means in the embodiment of FIG. 1, and FIG. 3A and 3B are explanatory views of the limit region, FIGS. 3A and 3B are explanatory diagrams of a knob and a lock button for setting the boundary line of the limit region in the x direction and the y direction of FIG. 2, respectively, and FIG. a) to (f) are explanatory views for explaining the timing of the signal for setting the limit region, and FIGS. 5 to 8 are for explaining the subject movement detecting means in the embodiment of FIG.
(A) and (B) are explanatory views showing the relationship between the divided tracking field of view and the subject image, and FIG. 6 is a block diagram of an apparatus for processing a signal obtained from the divided tracking field of view of FIG. 5, FIG. 7 is an explanatory view 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 9 in FIG. 1, and FIG. A block diagram showing a modified example of the movement detection circuit 9 in FIG. 1, FIG. 10 is a block diagram showing the details of the automatic focus detection circuit 13 in FIG. 1, and FIG. 11 is a screen of the subject in the embodiment of FIG. Explanatory diagram showing an aspect of adjusting the focal length according to the position inside,
FIG. 12 is a flow chart for explaining the operation method and action of the apparatus of FIG. 1, and FIGS. 13 (a) to 13 (h) are positions of the tracking field of view and the distance measuring field of view in the apparatus of FIG. FIG. 14 is an explanatory view showing a situation in which time changes in order from (a) to (h), and FIGS. 14 (A) and 14 (B) are explanations showing a relationship between a distance measuring field and a subject image in a conventional camera. It is a figure. DESCRIPTION OF SYMBOLS 1: Lens group for focus adjustment, 2: Lens group for changing focal length, 3: Imaging system lens group, 4: Solid-state imaging device as an example of imaging means, 7: Signal processing circuit , 8:
Tracking gate circuit, 9: subject movement detection circuit, 11: gate pulse generation circuit, 12: distance measurement gate circuit, 13: automatic focus detection circuit, 14: tracking field-of-view size determination circuit, 15:
AF motor drive device, 16: microprocessor, 1
7: Limit area setting circuit, 19: Zoom motor drive device,
23: color designation circuit, BA: limit area, TF: tracking field of view,
FF: Distance measuring field.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Takashi Amizo 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Plant (72) Inventor Akihiro Fujiwara 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Company Tamagawa Plant (72) Inventor Masahiro Takei, Tamagawa Plant, 770, Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. (56) Reference JP-A-57-123782 (JP, A)

Claims (1)

[Claims] 1. In a specific area on a shooting screen,
In an automatic tracking device for detecting the movement of a subject to be tracked and tracking the subject, a tracking region setting means for setting a tracking region for tracking the tracking subject in the specific region, and the tracking region The automatic tracking for extracting the characteristic of the tracking subject from the image pickup signal corresponding to the inside and controlling the tracking area setting means based on the change of the characteristic to change the set position of the tracking area in the specific area. Means for returning the tracking area to a predetermined standby position in the photographing screen while stopping the subject tracking operation of the automatic tracking means when it is determined that the tracking area has left the specific area At the standby position, the information indicating the preset characteristics of the subject is compared with the information extracted from the tracking area, and the comparison result is obtained. Determining means for determining that a subject is present at the standby position when the subject is within the predetermined dead band width, and restarting the automatic tracking operation of the automatic tracking means when the presence of the subject is detected at the standby position by the determining means A control means for controlling the camera.