JPS62272675A - Automatic focussing device - Google Patents

Abstract

PURPOSE:To form a video camera most suitable for focussing even when an object to be photographed is present in any position in a photographed picture by focussing on the hue component of the object desired to be photographed. CONSTITUTION:In a color difference vector chart for identifying the hue, a (R-Y) signal and a (B-Y) signal are defined to be orthogonal axes, a chrominance signal is obtained by the vector sum of both the signals. Namely, an arbitrary color C is represented by C=(R-Y) sin theta+(B-Y) Cos theta. Accordingly, by deciding the theta, the ratio of the (R-Y) signal and the (B-Y) signal can be determined and the color can be identified. By focussing making an area including the identified color an angle of view to the focussing by the fixed angle of view, the dimension of the angle of view and the position thereof are changed according to the area of the identified chrominance signal. Thereby, an automatic focussing can be effectively obtained to the object intended by a photographer.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an automatic focusing device that automatically adjusts the focus of a video camera.

[Conventional technology]

2. Description of the Related Art As an automatic focusing device installed in a photographing device such as a video camera, there is an automatic focusing device that focuses only on a subject in the center of the field of view of a photographed image, as described in, for example, Japanese Patent Application Laid-Open No. 56-56073.

FIG. 9 shows the relationship between the distance ring (hereinafter referred to as helicoid) position of the photographing lens and the voltage obtained by detecting the high frequency component of the video signal (hereinafter referred to as focal voltage) to explain the above-mentioned conventional technology. FIG.

The conventional focusing method (focusing method) described above takes advantage of the fact that the high-frequency component of the video signal being shot is maximized during focusing, and the lens is adjusted so that the high-frequency component of the video signal is maximized. Controls Helicoid.

In FIG. 9, the helicoid position X where the focal voltage is maximum is the focal point. The name "mountain climbing control" comes from the fact that the helicoid position is controlled so that it climbs the peak of the focal voltage.

By detecting this, the current helicoid position relative to the focal point position X can be determined, and mountain climbing control can be performed. Move.

Move.

Note that the determination conditions when the helicoid position is moved from b to the α direction are as follows.

Move.

Move.

・ 3. Figure 10 is a diagram for explaining the method of determining the angle of view in the prior art. (α) in the figure shows the field of view showing the video image, and (b) in the same figure shows the video signal within the angle of view as a time chart. It is a waveform diagram indicated by the axis "-."

In the figure ((L), the shaded area is the angle of view at which focusing is to be performed, and focusing is achieved by maximizing the high-frequency components of the video signal within this angle of view. The video signal within this angle of view is as shown in FIG. 6(b), and this signal is extracted using a one-shot multivibrator or the like.

In this way, conventionally, the focus is on the subject in the center of the photographed image, the angle of view is determined, and the subject within the angle of view is focused, so the subject that the photographer intends to photograph is As long as the subject is in the center, a good image can be obtained, and other subjects such as the background will not be in focus.

[Problem that the invention seeks to solve]

By the way, when shooting with a video camera, it is often said that you should avoid moving the video camera as much as possible.

Images taken while rapidly moving the camera are tiring to the eyes. This also applies when shooting a moving subject.

When an object moves from one end of the field of view to the other, the object intended to be photographed will extend out of the field of view, and conventional methods have not taken into consideration how to focus on such an object.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the problems of the prior art described in 1. and to provide a video camera that is suitable for focusing on an object intended to be photographed, no matter where on the screen it is being photographed. .

[Means for solving problems]

The above problem can be solved by focusing on the color (hue) of the subject and focusing on the color (hue component) of the subject to be photographed.

[Effect]

FIG. 11 is a color difference vector diagram for explaining a method for identifying hue (hereinafter referred to as "color").
When the Y) signal and the (+1-Y) signal are orthogonal axes,
It is shown that the color signal is determined by the vector sum of these two signals. That is, any color C is expressed by the following formula.

Therefore, by determining O, the (RY) signal and (B
-Y) It becomes possible to determine the signal ratio and identify colors.

In contrast to conventional focusing using a fixed angle of view, the present invention focuses on an area including the identified color as the angle of view, and the size and position of the angle of view change depending on the area of the identified color signal.

Thereby, automatic focusing can be reliably achieved for the subject intended by the photographer.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIGS. 1, 2, 3, 4, and 5.

FIG. 1 is a block diagram showing the configuration of an automatic focusing device of the present invention, in which 1 is a lens, 2 is a camera circuit, 2 is a video signal output terminal, 3 is a bypass filter, 4 is a signal delay circuit, 5 is an analog gate circuit, 6 is a detection circuit, 7 is a differential hold circuit, 8 is a motor drive circuit, 9 is a motor for rotating the helicoid of lens 1, 10 is a color discrimination circuit,
1oa is a vertical synchronization signal output terminal, IOb is a water IP synchronization signal output terminal, 10c is a (R-y) signal output terminal, l
Od is a (B-Y) signal output terminal r, IOe is a 1-signal input terminal, and IOf is a color identification signal output terminal r-.

First, a focusing operation using the configuration shown in the figure will be explained. An optical signal incident on the lens 1 is converted into an electric signal by the camera circuit 2, and a video signal is outputted to the terminal -f20-.

After this video signal is extracted only the high-frequency component of the video signal by a bypass filter 3, it is delayed by a signal delay circuit 4.
It is input to analog goo 1 to circuit 5. Now, let us consider the case where the analog circuits 1 to 5 pass the high-frequency components of the input video signals.

Note that this is the time to perform the focusing operation.

The video signal that has passed through the analog circuits 1 to 5 is detected by a detector 6. The output of the detector 6 is detected and becomes a voltage corresponding to the amount of high-frequency components of the video signal. This voltage is the focal voltage described earlier. As explained in the conventional example, the change in focal voltage when the edge position of the lens 1 is moved is stored in the differential hold circuit 7, and hill climbing control is performed by the motor drive circuit 8 and motor 9 to achieve automatic focusing. .

On the other hand, when the analog gate circuit 5 does not allow the input video signal to pass through, the focal voltage does not change even if the helicoid position of the lens 1 is moved. Therefore, at this time, it is assumed that the object is in focus, and the focusing device does not operate. Then, the color of the subject intended to be photographed is identified by the identification circuit 10,
By controlling the gate operation of the analog gate circuit 5, automatic focusing on a specific color becomes possible.

Next, the operation of the color identification circuit 10 will be explained separately for storing the color intended for photographing and identifying the photographic subject based on the stored color.

FIG. 2 shows the configuration of a circuit A for storing colors intended for photographing.

In the figure, 10 of each symbol is L, ], Ob,
], Oc.

], Oe are the same as the same symbols in FIG. 11, 12, 13.14 is one shot 1~mar
7. 1187 milliseconds, approximately 3 milliseconds, and approximately 25 milliseconds, respectively.
Generates a microsecond, approximately 10 microsecond pulse. 1
5 is an AND circuit, 16 is a sample and hold circuit, and 16 is an output terminal of the sample and hold circuits 1-6.

A nail surface synchronization signal is input to the one-shot multi 11 from a vertical synchronization signal output terminal 10 . Further, a horizontal synchronizing signal is manually inputted to the one-shot multi 13 from the horizontal synchronizing signal output terminal Ob.

Since the one-shot multi 11 has a pulse length of approximately 7 milliseconds, the output signal of the one-shot multi 12 is approximately 16 ms.
．． It starts approximately 7 milliseconds after the vertical synchronization signal of the camera circuit 2, which is output every 7 milliseconds, and has a pulse length of approximately 3 milliseconds.

This pulse is generated approximately 1 minute in the center of the screen in the vertical direction when the video signal output to the video signal output terminal -i'-2 is converted into an image.
7% and 11%.

On the other hand, since the one-shot multi 13 has a pulse length of approximately 25 microseconds, the output signal of the one-shot multi 14 is output from the camera circuit 2 every approximately 64 microseconds.
starts about 25 microseconds after the horizontal synchronization signal of about 1
It will have a pulse length of 0 microseconds. This pulse is transmitted to the video signal output terminal 2c1. This corresponds to approximately 16% of the center of the screen in the horizontal direction when the video signal output to is used as an image.

Therefore, by taking the logical product of the output signals of One Shot Multi 1.2.14, we can obtain the angle of view using the central part (shaded part) of one image as shown in Fig. 10 ((L) used to explain the conventional example). One Shot Multi 12.1
4 and the set signal pulse from the set signal input terminal ]Oe are logically ANDed by the AND circuit 15, and when the output is high, the sample hole 1 is connected to the circuit 16.
samples the color difference signal (RY) input from the (RY) signal output terminal 10c.

By the second operation, the subject (R-Y
) signal is stored in sample and hold circuit 16. Second
In configuration A in the figure, the (RY) signal input terminal is connected to the (B
It is easy to see that it is possible to capture the (B-Y) signal of the subject shown in the figure by replacing it with the signal input terminal A'.
shall be. (RY) of the subject photographed using circuits A and A'.

The (B-Y) signal or color is stored.

Next, the third step is about identifying photographic subjects using memorized colors.
This will be explained using figures.

FIG. 3 is a block diagram showing the configuration of a circuit for color recognition (111), and among the symbols in the figure, 1. The same symbols as those used in FIG. 2 indicate the same things, 17 is a subtraction circuit, 18 is a comparison circuit, 19 is an AND circuit, 19 is its output terminal, and 20 is a pulse width expansion circuit. In the figure, the (R-Y) signal stored in the circuit is the current (II-Y) signal input from the (R-Y) signal output terminal 1()o of the camera circuit 2 and the subtraction circuit 17. is subtracted by The absolute value of the subtracted value is a constant value V r e r
In this case, the output of the comparator circuit 18 becomes high, and currently,
It is recognized as equivalent to 02-Y)(, 9, in which the (RY) signal was stored. The circuit 1- below corresponds to circuit B surrounded by a dotted line.(E(-Y ) signal is also recognized by the circuit vT13' in the same way.Therefore, the output of the AND circuit 19 which is the AND of the output of the comparison circuit 18 for the (RY) signal and the comparison circuit 18 for the (B-Y) signal. The output to the terminal is high only for the video signal of the same color as the color intended for photographing, making color identification possible.The comparison circuit "8" has two reference values, Vref and -Vrcf. It can be easily constructed using a comparator circuit and a non-logical product.

- Although the circuit described above makes it possible to identify the color of the object that is intended to be photographed, it is necessary to ensure that the portion of the video signal output from the camera circuit VT2 that corresponds to the object of the identified color is The output signal of the AND circuit 19 is expanded by 11 in a pulse 11 expansion circuit 20 so as to pass through the circuit 4 to the analog game 1.

FIG. 4 is a circuit diagram showing a specific example of a pulse width widening circuit, in which l9cL is the output terminal of the AND circuit 19, and 21
22 is a diode, 22 is a buffer, 23 is a resistor 224 is a capacitor, ]Of is the output terminal of the color discrimination circuit mentioned earlier.

This circuit widens the pulse by making the XZ difference time constant very large compared to the time constant of the rise of the signal.

Since the video signal output from the camera circuit 2 is delayed by the signal delay circuit 4, the pulse 11] is expanded by the pulse expansion circuit 20 to approximately twice the amount of signal delay to produce the identified color. A color discrimination circuit output signal is obtained that allows even high-frequency components of the video signal of the horizontal outline of the object to pass through the analog gate circuit 5 reliably. This timing chart is shown in FIG. 5 (0-). From the figure, it can be seen that among the video signals output from the camera circuit 2, only the horizontal contour portion of the video signal of the color intended to be photographed and the high-frequency components of the video signal in the vicinity thereof pass through the analog gate circuit 5. Automatic focusing is made possible by controlling the helicoid position of the lens 1 using this signal. Figure 5 (l)
) shows the recognized color in the video image and the angle of view provided to focus on that color. The recognized color is indicated by a diagonal line, and the angle of view at which the image is to be focused is indicated by a broken line.

According to this embodiment, automatic focusing is performed by setting the angle of view for a specific color, so automatic focusing is possible no matter where the subject is in the image.

In the first embodiment of the present invention described below, first, the color of the object to be photographed is memorized at the center of the screen. This may be stored at any location as a cursor display. The advantage of this case is that there is a large degree of freedom when changing the photographic subject during photographing. Note that the cursor can be displayed on the screen using a known technique called superimpose.

In addition, the angle of view position for storage includes one-shot multi 11 in FIG. ．． This is possible by changing the pulse length of 13. To change the pulse length, we use a one-shot multi whose output pulse can be varied by using a DC control voltage.
This is linked to the superimposed cursor.

Further, the bypass filter 3 and the signal delay circuit 4 operate in exactly the same way even if the order of construction is reversed.

Furthermore, the bypass filter 3 is analog goo 1-circuit 5.
There is no problem even if it is connected after the .

FIG. 6 is a block diagram showing the configuration of the first embodiment of the present invention, in which the same reference numerals as in the diagram explaining the first embodiment indicate the same parts, 26 is a clock input terminal, 27 is a screen Position determination circuit 27^, b is its output terminal, 28 is reset 1
One end r-129,3] is a one-shot multi circuit that can vary the output pulse 111 by a DC control voltage, 30.32 is a one-shot multi circuit, and 33 is an 1-circuit.

Further, FIG. 7 is a diagram showing the field of view of a video image, and FIG. 8 is a block diagram showing the configuration of a viewing angle determining circuit.

In the second embodiment of the present invention, the video screen is divided into six parts as shown in FIG. This is the angle of view for focusing. This view angle determining circuit will be explained below.

By circuits B and B', output terminal 19 of AND circuit 19
If the color is good, the output becomes high in the video signal portion of the object having the same color as the stored color (11). The image determining circuit operates using this signal, a clock having a period of 1/120 seconds inputted from the clock input terminal 26, and a reset signal using a vertical synchronization signal inputted from the reset terminal 28.

The operation of the image determining circuit will be explained using FIG. This figure shows an example of the circuit configuration of the view angle determining circuit, in which 34 is a shift register circuit, and 35 is a voltage conversion circuit. The shift register circuit 34 has a 6-bit output, is reset to 1 by a reset signal input from the reset terminal 28, and shifts its output using a clock input from the clock input terminal 26. The output shifting 1~ continues until a high level signal is input from the output terminal 19σ- of the AND circuit 19. The output of the shift register circuit 34 is shifted every m seconds, and is reset by the vertical synchronizing signal, so that when the video screen is divided into six parts as shown in FIG. It will be revealed.

Therefore, the pulse width of the one-shot multi 29 in FIG. - When the output of the register circuit 34 is 4 to 6) By controlling the voltage through the terminal 27, it becomes possible to switch the viewing angle between the two halves and the lower half of the video screen.

Similarly, in the horizontal direction, the pulse width of the one-shot multi 31 in FIG. Shift 1 - When the output of the register circuit 34 is 2 or 5) (3) Voltage control is performed through the terminal f 27 h so that approximately 42 microseconds (when the output of the shift register circuit; 34 is 3 or 6) Let's do it. The pulse width of One-Shot Multi 30 is approximately 8.4 milliseconds, and the pulse width of One-Shot Multi 32 is approximately 8.4 milliseconds.The output terminal 10f of One-Shot Multi 30 has the colors intended for shooting when the video screen is divided into six. The angle of view is determined so that the angle of view is only that of the divided portion. The angle of view is determined based on the image after one field, and ■field is approximately 16.
The delay is 7 milliseconds, and this degree of delay is not a problem. Therefore, if the circuit of this embodiment is replaced with the color identification circuit of FIG. 1, automatic focusing on a specific color can be achieved.

According to the embodiment described in 1., it is possible to focus on a specific color and its surroundings.

For example, if red is stored in the autofocus device and the subject is a girl with a red ribbon in her hair, the focus will be accurate not only on the red ribbon but also on the girl's face. There is an effect that can be done.

An embodiment in which automatic focusing is performed on a specific color using color difference signals (RY) and (B-Y) has been described above.

In the embodiment, color difference signals of specific colors (RY), (B-Y)
Color identification was performed by storing the signal and comparing the signal level with the current color difference signal. In addition, the color identification is (RY),
It is also possible to determine the reliability of the (+3-Y) signal by comparing it with a stored level ratio.

The signal level ratio can be configured by two log amplifiers and a subtraction circuit. For color identification.

The advantage of using the signal level ratio of the (RY) and (B-Y) signals is that it is resistant to fluctuations in illuminance of the object being photographed. It is also possible to identify the decrease in the color difference signal level due to the low I of +K1 degree of the object by taking the ratio.

By the way, the color difference signal (RY) mentioned earlier.

(B-Y) Even in the method of memorizing signal intersections and performing color identification, AGC (Δut, o mat, ic
G a in Control) ΔD (Δu1
．． The effects of illuminance fluctuations can be removed by using a means to keep the video signal level constant regardless of illuminance fluctuations using Tris). Even if three colors, G) and blue (B) are used, it is still possible.

Alternatively, it is also possible to use known techniques such as chromakey or vector scope to identify the subcarrier phase.

Furthermore, by memorizing the level of the luminance signal when memorizing colors, it is possible to distinguish the subject to be focused on even when the same color has different saturation levels, and it is also possible to distinguish between subjects that need to be focused on even when the same color has different degrees of saturation. Focusing becomes possible.

In contrast to conventional focusing using a fixed angle of view, the present invention sets an area including the identified color as the angle of view, and focuses within this angle of view, and the size and position of the angle of view are determined by One feature is that the color signal changes depending on the area.

In the above embodiments, focusing is performed by mountain climbing S of the helicoid position, but the present invention is not limited to this. It is also possible to move the ball or compensator. In addition to the above-mentioned mountain climbing method, there is a method in which the optical path length is slightly changed to detect the inclination direction of the mountain and the focus is controlled in the focusing direction (for example, 60-4
(see Japanese Patent No. 2723).

〔Effect of the invention〕

゛19゛According to the present invention, since it is possible to focus on the color of the subject, it is possible to reliably obtain automatic focusing on the subject intended by the photographer, and also to focus on the subject intended by the photographer. Even if a third person crosses in front of the camera or an insect or the like moves by, the automatic focusing device does not react, so the video image will not be disturbed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention, FIG. 2 is a block diagram showing a circuit for storing colors, FIG. 3 is a block diagram showing the configuration of a circuit for identifying colors, and FIG. FIG. 4 is a specific circuit diagram of the pulse [11 widening circuit], FIG. 5 is an explanatory diagram of the operation of the color identification circuit, and FIG. 6 is a block diagram of the overall configuration of the viewing angle determining circuit showing the second embodiment of the present invention. , FIG. 7 is a diagram showing a video image, FIG. 8 is a configuration diagram of a field-of-view determining circuit, FIG. 9 is a characteristic diagram explaining automatic focusing operation, FIG. 10 is an explanatory diagram of field-angle determination, and FIG. The figure is a diagram showing color difference vectors. [Explanation of symbols] 1. Lens, 2. Camera circuit, 4. Signal delay circuit.
20° path, 5...Analog gate circuit, 3.Bypass filter, 6...Detection circuit, 7...Differential hold circuit, 8.
Motor drive circuit, 9...Motor, 10...Color identification circuit,
27... Angle of view determining circuit. 1st Otsutaku 2 Kuni A Cb) 1st] 1st line b' Ka 40 Yu 50 (α) 4 top or time Cノ) 1st Otome Riryou 70 Kan 8 Kob R 9th to α X b 1) Koitoi Device release 10r (α) (b) Gate 71st port (A: -Y) Glaze

Claims (1)

[Claims] 1. In an automatic focusing device for a video camera that controls a focus adjustment system of a photographing lens so as to maximize a contour component of a video signal during photographing, a first means for storing a hue component of a video signal; a second means for comparing the hue component in the video signal taken and the hue component in the video signal being photographed, and when they match, setting an angle of view that includes the hue component in the video signal being photographed; By controlling the focus adjustment system of the photographing lens so as to maximize the contour component of the video signal within the angle of view obtained by the second means, the subject to be focused can be photographed. An automatic focusing device characterized by being configured to be capable of automatic focusing regardless of the position within the field of view.