JPH07288733A - Video camera - Google Patents

Abstract

PURPOSE:To control a focus motor based on contour correction signals, to simplify circuit constitution for realizing an automatic focusing function and to suppress the cost. CONSTITUTION:Horizontal and vertical contour correction signals outputted from horizontal and vertical contour correction signal generation circuits 26 and 34 are added by an adder 40 and output signals from the adder 40 are supplied through an amplifier 42 to a standard cell IC 44. In the standard cell IC 44, after components below the standard level of input signals are cut, the components above the standard level are integrated in a horizontal video period and thus, an evaluation value is calculated. A microcomputer moves a focus lens 12 by the focus motor 48 so as to maximize the evaluation value and thus, the automatic focusing function is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera,
In particular, it relates to a video camera having an autofocus function, for example.

[0002]

2. Description of the Related Art As one of the operating principles of autofocus, there is one that utilizes the fact that the high frequency component of a video signal becomes maximum when the image is in focus. Therefore, in the conventional video camera 1 shown in FIG. 5, noise is removed from the video signal output from the sample hold circuit 2 by the trap circuit 3, and the low-level portion of the noise-free video signal is corrected by the gamma correction circuit 4. Lifted by an amplifier 5
It is given to the high pass filter (HPF) 6 via a. Then, the high frequency signal output from the HPF 6 is fed to the amplifier 5b.
To IC7 via. The IC 7 calculates an evaluation value by integrating the input high frequency signal for one horizontal video period, and gives this evaluation value to the microcomputer 8. Then, the microcomputer 8 controls the motor 9 so that the evaluation value becomes maximum,
This realized the autofocus function.

[0003]

However, in the conventional video camera 1 as described above, various circuits are required in order to generate a signal for calculating the evaluation value, and therefore the configuration becomes complicated and There was a problem that it was costly. Therefore, a main object of the present invention is to provide a video camera in which the circuit configuration for realizing the autofocus function can be simplified with a simple configuration and the cost can be suppressed.

[0004]

According to the present invention, there is provided a focus lens, an image pickup device, a contour correction signal producing means for producing a contour correction signal based on a video signal outputted from the image pickup device, and a contour correction signal having a predetermined level or more. The video camera includes a calculation unit that calculates an evaluation value obtained by integrating the components for a predetermined period, and a control unit that controls the position of the focus lens so that the evaluation value becomes maximum.

[0005]

For example, the horizontal and vertical contour correction signals output from the horizontal and vertical contour correction signal generating circuits are added by, for example, an adder, and the output signal from the adder is applied to, for example, a standard cell IC. In the standard cell IC, after components below the reference level of the input signal are cut, components above the reference level are integrated for one horizontal video period, for example, and the evaluation value is calculated by this. For example, the microcomputer controls the focus motor, for example, so that this evaluation value becomes maximum, and thereby moves the focus lens.

[0006]

According to the present invention, since the focus motor is controlled based on the contour correction signal, the circuit structure for realizing the autofocus function is simplified and the cost can be suppressed. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a video camera 10 of this embodiment includes a focus lens 12, and an image passing through this focus lens 12 is a CCD (Charge Coupled Devi).
ce) 14 and the CCD 14 creates an electrical signal corresponding to the image. The electric signal output from the CCD 14 is given to the sample hold circuit 16, and the sample hold circuit 16 creates a video signal. The video signal output from the sample hold circuit 16 is AGC.
After the gain is adjusted by the (Automatic Gain Control) circuit 18, the noise included in the video signal is removed by the trap circuit 20, and the low level part of the video signal is further lifted by the gamma correction circuit 22. It is input to the horizontal contour correction signal generation circuit 26 via 24. The video signal output from the 1H delay line 24 is also supplied to the horizontal contour correction signal generation circuit 26 and the adder 30 via a 0.1 microsecond delay line 28, and also a 0.1 microsecond delay line 32.
Is supplied to the horizontal contour correction signal generation circuit 26 via.
Therefore, the horizontal contour correction signal generation circuit 26 creates a horizontal contour correction signal based on the input video signal.

The video signal output from the sample hold circuit 16 is also directly input to the vertical contour correction signal generating circuit 34.
To the vertical contour correction signal generation circuit 34 via the 1H delay lines 36 and 38, and the vertical contour correction signal is created based on these video signals. The horizontal contour correction signal and the vertical contour correction signal output from the horizontal contour correction signal generation circuit 26 and the vertical contour correction signal generation circuit 34 are applied to the adder 30, and the video signal whose contour is corrected by the adder 30 Is output. The horizontal contour correction signal and the vertical contour correction signal are also added by the adder 40, and the output signal from the adder 40 passes through the amplifier 42 and then the standard cell IC4.
4 is input. Note that the horizontal and vertical contour correction signals are added because only one of the horizontal and vertical contour correction signals is created for a horizontally striped or vertical striped image, and if only one of them is supplied to the standard cell IC44, This is because the evaluation value is not calculated and the microcomputer 46 may not be able to control the focus motor 48.

In the standard cell IC44, the components below the reference level of the input signal are removed, and then integrated for one horizontal image period, whereby the evaluation value is calculated. The calculated evaluation value is given to the microcomputer 46,
The microcomputer 46 controls the focus motor 48 so that this evaluation value becomes maximum, and thereby moves the focus lens 12. The standard cell IC44 is an integrated circuit "IC9700" manufactured by Sanyo Electric Co., Ltd.
0 "can be applied. However, the operating frequency of" IC97000 "is set so that the standard cell IC44 performs the integral operation for calculating the evaluation value only for the frequencies of the horizontal and vertical contour correction signals. I need to start over.

In operation, when an image as shown in FIG. 2A is given to the CCD 14, the horizontal contour correction signal generating circuit 26 is given the horizontal image signals shown in FIGS. 2B to 2D. As a result, the horizontal contour correction signal generation circuit 26
Outputs a horizontal contour correction signal as shown in FIG. Also in the vertical contour correction signal generation circuit 34, although the pulse width is different (pulse width: 1H), FIG.
A vertical contour correction signal having the same shape as the horizontal contour correction signal shown in FIG.
The contour correction signal shown in is output. Standard cell I
At C44, the components of the contour correction signal shown in FIG. 2F at the reference level V or lower are cut, and the components at the reference level V or higher are integrated for one vertical video period. Since the calculated evaluation value changes with respect to the position of the focus lens 12 as shown in FIG.
The focus lens 12 is always controlled by 8 to increase the evaluation value, and when the evaluation value decreases, the focus motor 48 is rotated in the reverse direction, and the focus lens 12 is returned and stopped to the position where the evaluation value is the maximum. The microcomputer 46 also follows the fluctuation of the subject information (that is, the shape of the evaluation value curve changes and the current position is not the apex of the evaluation value curve), and always searches the apex of the evaluation value curve so that the current focus is set. It is monitored whether the position of the lens 12 is located at the maximum value of the evaluation value curve.

According to this embodiment, an evaluation value is calculated based on the contour correction signal output from the adder 40, and the focus lens 12 is moved by this evaluation value, so that a circuit configuration for realizing the autofocus function is provided. It will be simpler and less expensive. In this example,
Although the delay time of the delay lines 28 and 32 is 0.1 microsecond, the delay time of the delay lines 28 and 32 can be set arbitrarily. Further, in this embodiment, the horizontal and vertical contour correction signals are added by the adder 40, but it is also possible to add both signals by using the resistors R1 and R2 as shown in FIG. Of course.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2A is an illustrative view showing a video image given to a CCD 14, FIGS. 2B to 2D are waveform diagrams showing a horizontal video signal, and FIG. 2E is a waveform diagram showing a horizontal contour correction signal. And (F) is a waveform diagram showing horizontal and vertical contour correction signals.

FIG. 3 is a graph showing a relationship between a lens position and an evaluation value.

FIG. 4 is a circuit diagram showing a part of another embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional technique.

[Explanation of symbols]

 10 ... Video camera 26 ... Horizontal contour correction signal generation circuit 34 ... Vertical contour correction signal generation circuit 40 ... Adder 44 ... Standard cell IC 46 ... Microcomputer 48 ... Focus motor

Claims (2)

[Claims] 1. A focus lens, an image pickup device, a contour correction signal creating means for creating a contour correction signal based on a video signal output from the image pickup device, and a component of a predetermined level or more of the contour correction signal is integrated for a predetermined period. A video camera comprising: a calculation unit that calculates an evaluation value; and a control unit that controls the position of the focus lens so that the evaluation value becomes maximum. 2. The contour correction signal generating means includes horizontal contour correction signal generating means and vertical contour correction signal generating means.
The video camera according to claim 1.