JP3171871B2 - Magnetic recording and imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording and photographing apparatus for recording moving images and still images on a magnetic tape.

[0002]

2. Description of the Related Art Conventionally, as a VTR for recording a video signal and an audio signal, for example, a rotary two-head helical scan type VTR, a magnetic tape 1 is wound around (180 + θ) degrees or more as shown in FIG. 2 is traced by the rotating heads 3 and 4 for 180 degrees and the rotating cylinder 2 is θ, a video signal is recorded in a recording area 5 shown in FIG. 4, and a PCM-modulated audio signal is recorded in a recording area 6. What is known is.

A magnetic recording and photographing apparatus that records a video signal in the recording area 5 and records a digital still picture signal instead of an audio signal in the recording area 6 has been proposed. Since a still image has a small amount of information, it is possible to record all by scanning the recording area 6 a plurality of times.

Further, it is conceivable to apply AF control performed in a moving image photographing apparatus to this magnetic recording photographing apparatus. It is desirable that the time until the focusing of the AF performed by the moving image photographing apparatus is short because the photographing target is temporally continuous. However, considering the case where an object other than the object to be imaged traverses, the AF is too sensitive at a very high speed, and when viewed as a continuous image, an unpleasant sensation may occur. Smoothness is desired over sexuality.

[0005] As an automatic focus adjustment method responding to such a demand, a high-frequency component in a video signal obtained from an image sensor is extracted, and a photographing lens is driven so that the high-frequency component is maximized to perform focusing. A so-called hill-climbing method is known.

Next, a description will be given of an automatic focus adjustment method using a hill-climbing method in the moving image photographing apparatus shown in FIG.

An F lens 1 for focusing, a V lens 2 for zooming, a C lens 3 for correcting the focal plane, an aperture 4, and an RR lens for correctly forming an image on the image plane The light that has passed through the lens 5 in that order is imaged on the imaging surface of the image sensor 6 and converted into an electric signal. The video signal from the image sensor 6 is amplified to a predetermined level by a preamplifier 7, subjected to processing such as gamma correction, blanking processing, and addition of a synchronization signal by a camera signal processing circuit 8, and converted into a standard television signal. You.

The image pickup device 6 is slightly wobbled at a predetermined cycle in the optical axis direction in synchronization with the timing signal from the timing generation circuit 14 by the image pickup device drive circuit 22, and the image pickup surface is periodically vibrated back and forth. A change in the focus state according to the vibration becomes a modulation signal, and the imaging signal is modulated.

On the other hand, from the video signal from the preamplifier 7, a high-frequency component that changes according to the focus state is extracted by a band-pass filter (BPF) 9, and a focus circuit set in a part of the screen by a gate circuit 10. Detection area (ranging frame)
Only the signal corresponding to is extracted. Then, the peak value within the frame period is detected by the peak detection circuit 11, and the detected peak value is detected by the synchronous detection circuit 12 in synchronization with the timing signal from the timing generation circuit 14. That is, as described above, since the imaging element 6 is wobbled back and forth on the optical axis, the peak detection circuit 11 responds in opposite phases on the near side and the far side with respect to the focal point, respectively. Signals AN and AF, and a signal AM having the minimum amplitude at the focal point are added. These signals are synchronously detected by the synchronous detection circuit 12 at the same frequency as the wobbling frequency, and as shown in FIG.
The sign is opposite between the near side and the far side, and an output B that becomes zero at the focal point is obtained.

FIG. 6 shows changes in the output A of the peak detection circuit 11 and the output B of the synchronous detection circuit 12 when the lens is located at the far point and near point from the focal point. The output A exhibits a mountain-shaped characteristic which is maximum at the focal point, and becomes smaller as going to the far side and the near side.

The signal from the synchronous detection circuit 12 is properly amplified by an amplifier 13 and the focus motor drive circuit 1
6 to determine the front pin and the rear pin,
The lens 1 is driven to a focal point at a speed corresponding to the detection output. Next, the output of the synchronous detection circuit 12 is
, A specific loop gain is set, and the focus motor 17 is driven by the focus motor drive circuit 16 in accordance with the signal from the amplifier 13, and the focus of the F lens 1 is adjusted.

[0012]

However, such an automatic focus adjustment method is applied to a magnetic recording and photographing apparatus which records a video signal in the recording area 5 and a digital still picture signal in the recording area 6 as described above. Then, when capturing a still image, it takes time to focus, or hunting occurs during focusing, so that the imaging target cannot be momentarily fixed, and a photo opportunity may be missed.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to appropriately perform AF control at the time of shooting a moving image, and to achieve faster and more appropriate AF control at the time of shooting a still image. It is to provide a device.

[0014]

In order to achieve the above object, the present invention provides an image pickup device, a conversion device for converting a video signal from the image pickup device into a standard television signal, and a conversion device for converting the image signal into a standard television signal. Moving image signal processing means for processing the standard television signal thus converted into a moving image signal, and still image signal processing means for processing the standard television signal converted by the conversion means to obtain a still image signal; The still image signal from the still image signal processing means and the moving image signal from the moving image signal processing means are respectively recorded in a still image recording area and a moving image recording area on a video track formed obliquely to the longitudinal direction of the magnetic tape. A wobbling means for wobbling the image sensor in the optical axis direction, and a wobbling frequency of the wobbling means. Control means for increasing the frequency by a predetermined frequency when capturing a still image from when capturing a moving image, extracting means for extracting a high frequency component in a video signal from an image sensor wobbled by the wobbling means, and A peak detecting means for detecting a peak in a frame period of the high-frequency component; a detecting means for detecting a deviation from the focal point based on the peak detected by the peak detecting means; and a detecting means for detecting a deviation detected by the detecting means. Driving means for driving the focusing lens.

[0015]

In the present invention, the wobbling frequency of the wobbling means is increased by a predetermined frequency at the time of still image shooting from the time of moving image shooting by the control means, and the image sensor is wobbled in the optical axis direction by the wobbling means, and wobbled by the wobbling means. The high-frequency component in the video signal from the imaging device is extracted by the extraction unit, the peak within the frame period of the high-frequency component extracted by the extraction unit is detected by the peak detection unit, and based on the peak detected by the peak detection unit. The shift from the in-focus point is detected by the detecting unit, and the focus lens is driven by the driving unit according to the shift detected by the detecting unit.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

In the figure, 1 to 14, 16, 17, 21
Indicates the same parts as in FIG. Reference numeral 15 denotes a video signal processing circuit which processes a standard video signal from the camera signal processing circuit 8 into a moving image signal.

The still picture signal generation circuit includes an A / D conversion circuit 1
8, a rate conversion circuit 19, and a PCM conversion circuit 20. The A / D conversion circuit 18 converts a standard television signal from the camera signal processing circuit 8 into a digital signal. The rate conversion circuit 19 performs conversion for distributing the digital signal to a plurality of tracks in the PCM area. The PCM conversion circuit 20 performs PCM modulation on the signal from the rate conversion circuit 19.

Reference numeral 21 denotes a recording circuit for recording a still image or a moving image. Reference numeral 23 denotes an SV / MV mode switch, which switches the video signal processing circuit 15 and the A / D conversion circuit 18 to either the SV mode (still image mode) or the MV mode (moving image mode). 2
A recording switch 4 switches the recording circuit 21 to either the SV mode or the MV mode. 2
Reference numeral 5 denotes an image sensor driving circuit, and the image sensor 6 is driven according to the mode switched by the SV / MV mode switch 23.
Is changed in the optical axis direction, and the image pickup device 6 is wobbled to the front pin side and the rear pin side to modulate the optical path.

FIG. 2 is a flowchart showing a control procedure by the image sensor driving circuit 25.

In step S11, it is determined whether the imaging mode is the SV mode or the MV mode. If the result of the determination is that the mode is the SV mode, the process proceeds to step S12, where the loop gain of the closed loop is high. The still image shooting AF is controlled. Then, step S1
It is determined at 4 whether or not the recording switch 24 is ON. If the result of the determination is that the recording switch 24 is not ON, the process returns to step S11. On the other hand, if the recording switch 24 is ON, a still image is shot in step S15. On the other hand, if the result of determination in step S11 is that the camera is in the MV mode, processing proceeds to step S13, where AF control for moving image shooting is performed. Then, step S14
It is determined whether or not the recording switch 24 is ON. If the result of the determination is that the recording switch 24 is not ON, the process returns to step S11. On the other hand, if the recording switch 24 is ON, a moving image is shot in step S15.

In the SV mode, when the amount of wobbling of the image sensor 6, that is, the amplitude of the signal is increased, the amplitude of the optical path modulation component in the image signal output from the image sensor 6 increases. Therefore, the imaging device 6, a band-pass filter that extracts a signal component by optical path modulation from the imaging signal or a signal processing system of the periodic detection circuit 12, an amplifier 13, a focus motor driving circuit 16, and a focus control system including a focus motor 17 The closed loop gain is increased. As a result, the detection sensitivity with respect to the defocus amount increases, the output level of the synchronous detection circuit 12 increases, the focus motor 17 is driven at a higher speed than usual, and the AF operation can be performed at a high speed. Further, the detection sensitivity with respect to the defocus amount is increased, the detection accuracy of a delicate focus position near the in-focus is improved, and high-speed and high-precision AF control suitable for still image shooting can be performed.

In this case, the SV of the mode changeover switch 23
The standard television signal is converted into an A / D conversion circuit 18, a rate conversion circuit 19, a PCM conversion circuit 20 according to the mode output.
Respectively, and input to the recording circuit 21. Then, the recording circuit 21 records a still image in accordance with the output of the recording switch 24.

On the other hand, the SV / MV mode switch 23
If the mode switched by is the MV mode,
The signal from the camera signal processing circuit 8 is processed by the video signal processing circuit 15, input to the recording circuit 21, and a still image is recorded by the recording circuit 21 according to the output of the recording switch 24.

[0026]

As described above, according to the present invention,
With the above configuration, there is an effect that the AF control at the time of shooting a moving image can be appropriately performed, and the AF control at the time of shooting a still image can be performed more quickly and appropriately.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing a control procedure by an image sensor driving circuit 25 shown in FIG.

FIG. 3 shows a V for recording and reproducing a video signal and an audio signal.
FIG. 3 is a diagram showing a magnetic tape running system of the TR.

FIG. 4 is a diagram showing an example of a recording track on a magnetic tape by the heads 3 and 4 shown in FIG. 3;

FIG. 5 is a block diagram illustrating a configuration of a moving image photographing device.

6 is an explanatory diagram for explaining an automatic focus adjustment method employed in the moving image photographing device shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 F lens 2 V lens 3 C lens 4 Aperture 5 RR lens 6 Image sensor 7 Preamplifier 8 Camera signal processing circuit 9 BPF 10 Gate circuit 11 Peak detection circuit 12 Synchronous detection circuit 13 Amplifier 14 Timing generation circuit 15 Video signal processing circuit 16 Focus Motor drive circuit 17 Focus motor 18 A / D conversion circuit 19 Rate conversion circuit 20 PCM conversion circuit 21 Recording circuit 23 SV / MV mode switch 24 Recording switch 25 Image sensor driving circuit

Claims (1)

(57) [Claims] 1. An image sensor, a conversion unit for converting a video signal from the image sensor into a standard television signal, and a moving image signal for processing the standard television signal converted by the conversion unit into a moving image signal Processing means; still image signal processing means for processing a standard television signal converted by the conversion means into a still image signal; a still image signal from the still image signal processing means; A magnetic recording and photographing apparatus having a recording means for recording a moving image signal from a still image recording area and a moving image recording area on a video track formed obliquely with respect to the longitudinal direction of the magnetic tape. Wobbling means for wobbling in the axial direction, and a wobbling frequency of the wobbling means which is higher by a predetermined frequency at the time of still image shooting than at the time of moving image shooting. Control means; extracting means for extracting a high-frequency component in a video signal from the image sensor wobbled by the wobbling means; and peak detecting means for detecting a peak in a frame period of the high-frequency component extracted by the extracting means. And detecting means for detecting a shift from the focal point based on the peak detected by the peak detecting means, and driving means for driving the focus lens in accordance with the shift detected by the detecting means. Magnetic recording and imaging device.