JPH04318770A - Movie camera provided with still picture pickup function - Google Patents

Abstract

PURPOSE:To obtain a still picture close to a focusing state by moving an image pickup lens in a direction that a high frequency component extracted from a CCD or a contrast is increasing and driving a shutter driver when they are changed to be decreasing. CONSTITUTION:A movie camera 10 has a detection circuit 38, a still controller 68, a focus drive circuit 76 and a counter 93. When a still switch 25 is operated during movie pickup, the circuit 76 is activated under the control of the controller 68 to adjust focus. Then a detection circuit 38 discriminates focusing when a high frequency component or a contrast extracted for each focus adjustment is transited from the increasing state into the decreasing state or a count of the counter 93 counting the focus adjustment reaches a preset value. A strobo 20 is synchronized at this point of time to pick up a still picture and the still picture with excellent focus is picked up.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movie camera equipped with a still image photographing function that makes it possible to photograph still images with good focus.

0002

2. Description of the Related Art Recently, movie cameras that can easily record moving images (hereinafter referred to as movies) have become popular. This type of movie camera uses autofocus using the extreme value method (
The AF mechanism has a mechanism (hereinafter referred to as AF), and this AF mechanism increases the high frequency component value or contrast value generated at the outline of the image as the in-focus state of the image of the subject imaged on the image sensor (CCD) approaches the optimal value. The focus adjustment mechanism is controlled in a direction in which the high-frequency component value or the contrast value always increases by paying attention to the fact that the value increases, and performs so-called mountain climbing control.

It is desired that a movie camera having such an AF mechanism be able to freeze one frame of a movie as a still.

0004

[Problem to be Solved by the Invention] However, when trying to take a still image with the above-mentioned movie camera, the AF mechanism performs hill-climbing control during movie shooting, so the focus is relatively close to the in-focus position. Unfortunately, there are times when the subject is not in focus.

Therefore, in order to solve these problems, the present invention displaces the imaging lens in a direction that increases the high frequency component value or contrast value extracted from the CCD.
By assuming the position of the imaging lens when the high-frequency component value or contrast value transitions from rising to falling as the in-focus position, a still image shooting function is provided that can obtain a still image with a focus that is extremely close to the in-focus state. The purpose of the present invention is to provide a movie camera equipped with the following functions.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a shutter driver for driving a shutter, an image sensor for electrically reading image information of a subject, and a focus by displacing an imaging lens. a focus driver circuit that performs adjustment; an extraction unit that extracts a high frequency component value or contrast value included in the image information; a storage unit that stores the high frequency component value or contrast value; and a high frequency component value or contrast that is extracted. The present invention is characterized by comprising a control means for driving the focus driver circuit in a direction in which the value increases and energizing the shutter driver when the focus position is determined.

[0007]

[Operation] In the movie camera according to the present invention, the extraction means extracts the high frequency component value or contrast value contained in the image information of the subject imaged on the image sensor, and the extracted high frequency component value or contrast value increases. In this direction, the focus driver circuit displaces the imaging lens. Then, when the transition of the high frequency component value or the contrast value changes from increasing to decreasing, the control means drives the shutter driver.

[0008] Therefore, it is possible to obtain a still image with focus quality that is extremely close to that of an in-focus state.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a movie camera according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a movie camera according to this embodiment, and FIG. 2 is a side view showing the external appearance of the movie camera.

In FIG. 2, reference numeral 10 indicates a movie camera, and the movie camera 10 includes a camera body 12 and a grip 14. The camera body 12 includes an optical system 16.
, a sound collecting microphone 18, and a hop-up strobe 20
and a finder 21, and a cassette loading section 23 into which a video cassette 22 is loaded. The grip 14 has a movie image shooting switch (
A still image photographing switch (hereinafter referred to as a still switch) 25 is provided.

In FIG. 1, the optical system 16 includes the imaging lens 2.
6a, 26b, an aperture 28 made of an iris, and a CCD 30 that electrically reads image information formed.

The signal processing section 32 includes a sample hold circuit 34 for sampling the image signal read by the CCD 30, and an AGC as a gain controller for the image signal.
It consists of a circuit 36 and a detection circuit 38 that extracts signals for controlling focus, iris, etc. from the image signal.

The image processing unit 40 includes a color signal separation circuit 41 that separates an image signal into color signals of three primary colors, a Low Pass Filter (hereinafter referred to as LPF) 42 that extracts a luminance signal, and a γ correction for the luminance signal. , a delay line 46 that performs edge enhancement processing, and an FM modulator 48 that frequency modulates the luminance signal processed by these circuits. Further, the image processing section 40 converts the image signal output from the color signal separation circuit 41 into a C.
LP that extracts color signals such as R and CB and luminance signal YL
F50 and a matrix (hereinafter referred to as MTX) circuit 5 that converts these signals into color signals R1, G1, and B1 signals.
2, a delay line 53 connected to the MTX circuit 52, and an AWB (Auto White Balan).
e) A circuit 54, a process circuit 56 that converts the three primary color signals R, G, and B output from the AWB circuit 54 into chroma signals, and a low frequency modulation circuit that performs low frequency modulation processing on the chroma signals. 58.

The image recording section 59 includes an amplifier 60 for amplifying the signals output from the FM modulator 48 and the low frequency modulation circuit 58, a magnetic head 62 for recording image information on the video cassette 22, and the like.

The control unit 64 includes a movie controller 66 and a still controller 68, and the movie controller 66 includes a ROM 70 that stores a program for controlling the movie camera 10, and a RAM 72 that temporarily stores information during control. , the movie switch 24, and the detection circuit 38 are connected, and the imaging lens 26b
A focus drive circuit 76 for driving the diaphragm 28, an iris drive circuit 78 for opening and closing the aperture 28,
An SSG (Synchronism Signal Ge) outputs a synchronization signal for energizing the CD drive circuit 80.
nerator) circuit 82, the AGC circuit 36 and the AWB circuit 54 are connected.

In this case, the iris drive circuit 78 is connected to the common terminal of switch S1, and the iris drive circuit 78 is connected to the common terminal of switch S1.
By connecting the movie controller 66 to the terminal, the iris drive circuit 78 and the movie controller 66 are connected via the switch S1. Similarly SS
The G circuit 82 is connected to the movie controller 66 through the switch S2, the AGC circuit 36 through the switch S3, the AWB circuit 54 through the switch S4, and the focus drive circuit 76 through the switch S5.

By connecting the output terminal of the still controller 68 to the S side terminals of the switches S1 to S5,
When the switches S1 to S5 are switched, the iris drive circuit 78, the SSG circuit 82, the AGC circuit 36, and the
It is connected to the WB circuit 54 and focus drive circuit 76. The still controller 68 includes a still switch 25 for still image shooting, a strobe switch 86 for driving a strobe, and a character generator 88 that generates a character for displaying comments in the viewfinder 21.
and a detection circuit 38, an iris position detector 90 that detects the open/closed state of the iris, and a RAM 9.
2 is connected. The still controller 68 includes a charging section 94 of the strobe 20, a strobe control section 96, and a light emitting section 9.
8 and is also connected to the CCD drive circuit 80 and the movie switch 24, and has a counter 93.

The output terminal of the still switch 25 and the control terminals of the switches S1 to S5 are connected, and the switches S1 to S5 are switched by the trigger of the still switch 25.

In this case, the detection circuit 38 constitutes an extraction means, the RAM 92 constitutes a storage means, and the still controller 68 constitutes a control means.

Next, the operation of taking a movie image using the movie camera 10 configured as described above will be explained with reference to FIGS. 1 and 2.

First, when the movie switch 24 is operated, the movie controller 66 reads the initial value for movie shooting from the RAM 72, controls the CCD drive circuit 80 via the SSG circuit 82, and sets the shutter speed to 1/60 second. At the same time, the reference amplification gain of the AGC circuit 36 is set to 0 dB. In synchronization with the 1/60 second vertical synchronization signal output from the SSG circuit 82, the CC
D30 electrically reads the formed image information and converts it into an image signal. The image signal is sampled and held in a sample and hold circuit 34, and then output to a detection circuit 38 and an AGC circuit 36, and the detection circuit 38 extracts focus information consisting of a high frequency component value or a contrast value from the input image signal, It is output to the movie controller 66.

On the other hand, from the sample hold circuit 34 to the AG
The detection circuit 38 extracts exposure information from the image signal input via the C circuit 36 and sends it to the movie controller 66.
Output to. That is, the detection circuit 38 detects the image signals output from the sample hold circuit 34 and the AGC circuit 36, respectively, extracts focus information and exposure information, and outputs them to the movie controller 66. This focus information, for example, the so-called Front Focus (which is focused on the subject side rather than the imaging plane of the CCD 30).
Movie controller 6 into which the information (front pin) was input
6 is a focus drive circuit 7 according to the front focus information.
6, the imaging lens 26b is driven so that the image of the subject is focused on the CCD 30 by driving a motor (not shown) or the like through the CCD 30.
On the optical axis and in the CCD 30 direction (Fig. 1, arrow X1 direction)
Displace it to.

Similarly, the movie controller 66 receives the exposure information outputted from the detection circuit 38, for example, the information that the amount of light is less than the appropriate amount of light, and energizes the iris drive circuit 78 to adjust the aperture made of iris blades. 2
8 to increase the amount of light. In this case, when the exposure is insufficient even when the aperture 28 is opened to the maximum, the movie controller 66 sends a control signal to the AG to obtain proper exposure.
The signal is outputted to the C circuit 36, energizes an amplification gain changeover switch (not shown), and increases the amplification factor gain. At this time, the open state of the aperture 28 is detected by the iris position detector 90 and input to the still controller 68.

On the other hand, the image signal output from the AGC circuit 36 to the color signal separation circuit 41 is separated into a luminance signal and a color signal, and the luminance signal is subjected to offset removal processing by the LPF 42, and then subjected to γ correction. 0 by circuit 44.
After the signal is subjected to γ correction of 45, and furthermore, its contour is emphasized by a delay line 46, modulation processing is performed by an FM modulator, and the signal is input to the AMP 60. Color signal separation circuit 41 to L
YL, CR, and CB signals are extracted from the image signal output to the PF 50, and the matrix circuit 52 generates R1, G1, and B1 color signals under the action of the delay line 57.
The white balance is adjusted by the AWB circuit 54,
The signal is converted into a chroma signal by the process circuit 56 and input to the low frequency modulation circuit 58.

The chroma signal becomes a color signal subjected to low frequency modulation processing by the low frequency modulation circuit 58, and becomes an AM signal.
It is input to P60. This color signal is transmitted to the FM modulation circuit 4.
The signal is amplified by the AMP 60 along with the luminance signal input from the AMP 60, applied to the magnetic head 62, and magnetically recorded on the video cassette 22 as image information.

By the way, A is composed of a detection circuit 38, a still controller 68 and a focus drive circuit 76.
As shown in FIGS. 4(a) to (c), the F mechanism is 1/6
The focus position is automatically detected by displacing the imaging lens 26b in a direction in which the high frequency component value or contrast value output from the detection circuit 38 increases in synchronization with the vertical synchronization signal every 0 seconds, but the movie camera 10 Since the AF mechanism uses the extreme value method, it cannot stay at the in-focus position (see Figure 4, (c)), and the in-focus position cannot be changed as shown in Figure 4 (c) to (e). 4, and control is being performed within the ranges A and B in FIG.

[0028] While shooting the above movie, press the still switch 2.
5 is operated at the timing of ■ in FIG. 4, the control signal output from the still switch 25 switches the switches S1 to S5, and the iris drive circuit
8, SSG circuit 82, AGC circuit 36, AWB circuit 54
A focus drive circuit 76 is connected to the still controller 68. The still controller 68 is synchronized with the positive edge of the first vertical synchronization signal (Fig. 4,
), resets the counter 93 that counts the number of focus adjustments (step S1), reads the high frequency component from the detection circuit 38, and stores this value F1 in the RAM 92 (
(See FIG. 4, ■) (Step S2).

Next, the still controller 68 moves the imaging lens 26b via the focus drive circuit 76 to a position on the optical axis and near the CCD 30 (see arrow X1 in FIG. 1).
direction) by a predetermined distance, the counter 93 counts 1, and the second vertical synchronization signal (FIG.
, see ■)), the detection circuit 3
The high frequency component value or contrast value is read from 8, and this value F2 is stored in the RAM 92 as in step S2 (step S3).

The still controller 68 compares the read high frequency component values F1 and F2 (step S4).
, if F2 is larger than F1 (F1<F2), the imaging lens 26b is displaced by a predetermined distance in the same direction as step S3 (in the arrow X1 direction in FIG. 1), and the counter 93 is further At the same time, the high frequency component is read from the detection circuit 38, this value F3 is stored in the RAM 92 (step S5), and the high frequency components F2 and F3 are compared (
Step S6). If F3 is larger than F2 (F2<F3), it is determined whether the count value of the counter 93 matches a preset value, for example, 5 (step S7), and if they do not match, step Perform steps 5 to 7.

Further, in step S4, when the value of the high frequency component decreases (F1>F2), the still controller 68 determines that the direction of displacement of the imaging lens 26b is opposite to the focusing direction, and moves the imaging lens 26b. It is displaced in the far direction from the CCD 30 (in the X2 direction in FIG. 1), adds 1 to the counter 93, and reads the high frequency component in synchronization with the vertical synchronization signal (step S9), and proceeds to step S6.

On the other hand, when the value of the high frequency component decreases in step S6 (F2>F3), that is, when the value of the high frequency component changes from ■ to ■ in FIG. number of displacements,
That is, when the number of focus adjustments matches the preset value 5, the still controller 68 assumes that the focus is in focus, energizes the light emitting unit 98 of the strobe 20 to emit strobe light, and displays the still image. Take an image (
(See FIG. 4, ■) (Step S8).

In this way, the image signal read by the CCD 30 is recorded on the video tape 22 by the magnetic head 62 of the image recording section 59 via the sample hold 34, the AGC circuit 36, and the image processing section 40.

When the still photography synchronized with the strobe light emission is completed through the above steps, movie photography continues until the still switch 25 is operated next (FIG. 4,
■Reference).

In this case, in this embodiment, when the still switch 25 is operated during movie shooting, the imaging lens 26b is moved in the direction in which the high frequency component value or contrast value of the image information read via the detection circuit 38 increases. When the value of the high frequency component changes from increasing to decreasing, or when the number of adjustments of the imaging lens 26b matches the preset value 5, the position of the imaging lens 26b at this time is determined. The camera assumes the focus position and fires the strobe to take a picture.

Therefore, it is possible to obtain the position of the imaging lens 26b extremely close to the in-focus position by using the AF mechanism of a movie camera, in which it is difficult to obtain the true in-focus position.
A still image that is in focus can be obtained.

Furthermore, by comparing the number of times the imaging lens 26b is displaced with a preset value 5 and photographing a still image when they match, the still image can be captured within a certain period of time after the still switch 25 is operated. The movie image can be photographed, the photographing opportunity is not missed, and the movie image can be rapidly continued to be photographed, so that the continuity of the movie image is not impaired.

[0038]

[Effects of the Invention] According to the movie camera according to the present invention,
The following effects can be obtained.

When the still switch is operated, the imaging lens is gradually displaced in a direction in which the high frequency component value or contrast value included in the image information increases, thereby increasing the transition of the extracted high frequency component value or contrast value. By activating the flash and taking a picture when the amount of light starts to decrease, it is possible to obtain high-quality still images that are extremely close to being in focus.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a movie camera according to the present invention.

FIG. 2 is a side view showing the appearance of the movie camera according to the present invention.

FIG. 3 is a flowchart showing the operation of still photography by the movie camera according to the present invention.

FIG. 4 is a timing chart showing the timing of still photography in the movie camera according to the present invention.

[Explanation of symbols]

10...Movie camera 1
2...Camera body 14...Grip
16...Optical system 20...Strobe
24... Movie switch 25... Still switch 2
6a, 26b...imaging lens 30...CCD
34...Sample hold circuit 36...AGC circuit
40... Image processing section 59... Image recording section
66...Movie controller 68...Still controller 76...
focus drive circuit

Claims (1)

[Claims] 1. A shutter driver for driving a shutter, an image sensor for electrically reading image information of a subject, a focus driver circuit for adjusting focus by displacing an imaging lens, and a high frequency signal contained in the image information. an extraction means for extracting a component value or a contrast value; a storage means for storing the high frequency component value or the contrast value; and driving the focus driver circuit in a direction in which the extracted high frequency component value or contrast value increases; 1. A movie camera equipped with a still image shooting function, comprising: control means for energizing the shutter driver when it is determined that the in-focus position is reached.