JPH02130080A - Video camera system - Google Patents

Abstract

PURPOSE:To obtain a satisfactory still picture having sufficient brightness by securing the light quantity of the same extent as the time of being a moving picture corresponding to the shutter speed of an electronic shutter with a stroboscopic light emission at the time of photographing a still picture. CONSTITUTION:At the time of being a still picture mode, by operating a switch 10, an electronic shutter is operated at a shutter speed set to a shutter setting button 21, and at such a time, a stroboscope 17 is light-emitted and at an image pickup element 4, the charge of the same extent as the time of being the moving picture mode is accumulated. Namely, the stroboscope 17 is light-emitted so that a charged quantity B of the same extent as a charge quantity A accumulated for 1/60 seconds at the nearby field in the moving picture mode can be accumulated for shutter speed t1 seconds. Thus, without giving the bad influence to the moving picture, the satisfactory still picture can be photographed.

Description

[Detailed Description of the Invention] <Industrial Utilization Public Expenses> The present invention relates to a video camera system, and it is possible to control the charge accumulated on an image sensor by the operation of an electronic shutter so that it becomes a predetermined amount, thereby adversely affecting a moving image. This device has been devised so that it can take good still images without any problems.

<Prior Art> Some recent video cameras, especially video cameras using CCDei image elements, have electronic shutters, and by operating the electronic shutter as appropriate while capturing a moving image, the electronic shutter is recorded as a still image. It is now possible to individually photograph the desired items to be recorded in the same manner as when recording with a still camera.

Since one screen and one field of the NTSC television screen is made up of 1/60 seconds, the shutter speed is usually 1/60 seconds.
It can be considered as 60.

That is, the signal charge accumulated in the lli element of COD is 176
It is generated by photoelectric conversion of light incident during a period of 0 seconds, and is read out once every 17eo seconds.

Most of the image sensors in current video cameras are called field iFm and have a shutter speed of 1780 seconds, but some have a shutter speed of 1730 seconds.

This is a frame! It is called a product to distinguish it from the former.

In any case, in a conventional video camera, if the subject or the video camera being photographed moves during 1730 or 1760 seconds, the image becomes blurred. On the other hand, in an image sensor such as a COD, the signal accumulation time can be changed by a control signal. In an electronic shutter, a signal accumulation time of 1760 or less is usually arbitrarily selected to obtain 7, and this signal accumulation time will be referred to as the shutter speed of the electronic shutter.

Field 1sl here! l! The principle of the electronic shutter in the CCD will be explained below. The signal charge multiplied by 'W' when light hits one pixel of the COD increases with time, as shown in the third flash.1. If the amount of light is constant, the charge C will increase linearly when L11/60 seconds have elapsed.If the shutter speed of the electronic camera is set to t, then (1760 to t , at the time of J, at the third stage, at the time I!・Discard the charge to the flow input.As a result, the parasitic charge in the pixel section becomes 0.

However, since the light continues to COD and hits τ and T, the accumulated charge R increases again with the same slope, and the charge C is initially accumulated after the shutter speed t of the electronic shutter has elapsed.

At this time, when the charge (-1 is read out as the chair charge) is given a -j, /- lead shift pulse, the charge is -7.
・LL above time @t2(ζ, CCD FJ ICM Re
For example, as shown in FIG. 4, the vertical synchronizing pulse V immediately after t- when the electronic shutter is operated. Based on the above, it is known to apply a sweep pulse P9 of the same BM as the horizontal synchronizing signal to the DC bias of the CCD (7) Geever flow drain, and sweep out unnecessary charges from the COD. . That is, in the field in which a still image is being photographed, a sweep pulse is supplied to the COD during the period (1760-t,) from the trailing edge of the vertical synchronization signal , and during the second half of the same field corresponding to the shutter speed t. The electric charge Ct accumulated in the signal is read out as a signal electric charge.

Thus, in a video camera equipped with an electronic shutter, by setting the shutter speed appropriately and selecting the still image mode while shooting a moving image, a still image can be taken as appropriate. The video signal at this time includes a field shot in the still image mode intermixed with a field shot in the moving image mode.

<Problems to be Solved by the Invention> As mentioned above, in a still image taken by a video camera with an electronic shutter in the prior art, the signal charge is the charge C5 accumulated during the period corresponding to the shutter speed t. As the shutter speed 1t becomes faster than 1760 seconds, the signal charge decreases in proportion to the shutter speed compared to the signal charge of the field photographed in the moving image mode, and the reproduced image becomes darker accordingly.

Therefore, when photographing in still image mode, some cameras are designed to emit a strobe light in synchronization with the operation of the electronic shutter. However, when the strobe is emitted in this way, a new drawback arises in that the reproduced image becomes blown out due to overexposure of several fields in the static mode and a<e in the image mode. . This is because the response speed of the aperture due to automatic exposure t4vjg of a video camera is generally slow, so in video mode due to strobe light emission, excessive reflected light from the subject enters the solid-state image sensor such as COD, and the W product charge is This is because the white level of the video signal is reached.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a video camera system that can take good still images without adversely affecting moving images.

Means for Solving the Problems> The configuration of the present invention that achieves the above object is as follows: Video information is read out and recorded from an image sensor at fixed time intervals by selecting a video mode! [l! It has an electronic shutter capable of photographing an I-image, and also capable of photographing a still image, which is video information that is read out and recorded in an arbitrary time width, by driving the electronic shutter of the image sensor by selecting a still image mode. A video camera system has a light emitting source that operates in a frame or field in still image mode to emit flash light, and a light receiving element that receives reflected light from the subject, and the light receiving element receives light as the light emitting source emits light. The present invention is characterized in that the electronic shutter is controlled so that the amount of light incident on the image sensor reaches a predetermined amount based on the reflected light.

According to the present invention having the above configuration, the electronic shutter is controlled so that the amount of light incident on the image sensor l\ reaches a predetermined amount based on the reflected light received by the light receiving element as the light emitting source emits light. During moving images, even if the electronic shutter operates at a shutter speed that is generally shorter than the time corresponding to the readout pulse interval from the image sensor, a sufficient amount of charge accumulates in the image sensor to accommodate the reflected light from the subject. be done.

Practical example Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. As shown in the figure, switch 1 is used to select the video mode, and when the recording switch 11 is turned on, switch 1 is used to select the video mode.
The driver 3 is driven via the system controller 2 by operating the CCI with electronic shutter.
) is the accumulated charge accumulated in each pixel of the image sensor 4 as 1
It is read out every 760 seconds. At this time, the accumulated charge read out from the image sensor 4 is supplied to a signal processing circuit 6 via a preamplifier 5, converted into a video signal by this signal processing circuit 6, and then recorded via a recording amplifier 7 and a video head 8. It is recorded on a magnetic tape 9 which is a medium.

In such a video mode, the switch 12 is connected to the contact 12.
a is selected and the output signal of the continuous light light receiving element 13 is supplied to the AE control section 14. At this time, the continuous light receiving element 13 sends out a signal representing the amount of reflected light from the subject. Further, the AE control unit 14 determines the opening degree of the diaphragm based on the output signal of the continuous light light receiving element 13, and controls the diaphragm 16 via the system controller 2 and the diaphragm control unit 15 to achieve this opening degree. The diaphragm 16 is a mechanical diaphragm, and the response speed is relatively slow, although the response speed is sufficient in the movie mode.

The switch 10 is for selecting the still image mode, and by operating this switch 10, the switch 12 is switched to select the contact 12b via the system controller 2, and the strobe 17 is made to emit light. To be more specific, switch】2 is switch 1
The strobe 17 is controlled by the system controller 2 so as to be switched by the first vertical synchronizing signal, which is the readout pulse of the image sensor 4 after the operation of 0, and the strobe 17 is operated by the vertical synchronizing signal on the condition that the strobe light emission switch 18 is operated. Ru. The flash light receiving element 19, which has a fast response speed, supplies a signal representing the amount of light reflected from the subject when the strobe 17 emits light to the AE control unit 14 via the switch 12. As a result, the AE control section 14 controls the electronic shutter control section 20 via the system controller 2 based on the output signal of the flash light receiving element 19, and also controls the electronic shutter control section 20 based on the output signal of the flash light receiving element 19.
Controls the light emission time. At this time, the aperture 16 is fixed at the opening immediately before the still image mode, that is, the opening immediately before the switch 12 is switched to contacts 1 and 2b.

Furthermore, the shutter speed of the electronic shutter is basically set based on information representing the shutter speed that is set with the shutter speed setting button 21 and supplied to the system controller 2, but taking into account the light emission characteristics of the strobe 17, If a sufficient amount of light is not accumulated in the image sensor 4 even if the strobe 17 is emitted for the shutter speed of the electronic shutter, the AE control unit 1
4, the AE control unit 14 issues a command to the system controller 2 to automatically change the shutter speed. This can prevent artificial shutter speed setting errors.

On the other hand, if there is sufficient external light for the shutter speed, the strobe 17 will not emit light even in the still image mode.

That is, in consideration of battery life, in this embodiment, the strobe 17 emits light when the following conditions (1) to (4) are met, and when the AE control unit 14 determines that strobe light emission is necessary. It looks like this.

■ When the recording switch 11 is operating, ■ When the strobe light emitting switch] 8 is not operating, ■ When the shutter speed is set with the shutter speed setting button 21, the memory recording switch 22 Switch 23 and memory control unit 2 via controller 2
This is for controlling 4 and recording still images ξ. These still 1 and 2 images (ζ include not only the video signal of a certain Fino L! in the still image mode, but also the video signal of a certain Fino L! in the video mode. That is, 11, for example, the video signal of a video camera When you come across an image that you want to keep as a still image while looking through the viewfinder, you can record the image at that time as a still image by turning the recording switch 22 to 1. , the accumulated charge of the image sensor 4 at this time is the A/D converter 25 and the switch 23.
and image memory 2, which is a storage means, via connection 26.
7 and stored. The image memory 27 can be easily formed by an IC card or the like having an appropriate storage capacity (for example, for several fields), and stores the accumulated charge corresponding to each still image at an address designated by the memory control unit 24. It looks like this.

Further, the image memory 27 is housed in a memory cartridge 28, and can be attached to and detached from the connector 26 in this state.

In this embodiment, when in the moving image mode, video information of the subject is recorded on the magnetic tape 9 in exactly the same manner as in the prior art.

On the other hand, in the still image mode, the electronic shutter operates at the shutter speed set in the shutter setting button 21 by operating the switch 10, but at this time, the strobe 17 emits light and the image sensor 4 is displayed as in the moving image mode. The same amount of charge is accumulated. That is, as shown in FIG. 2, the steps 1 to 1 are set so that the same amount of charge B as the amount of charge A accumulated in 1760 seconds in the most recent field is accumulated in the shutter speed of 13 seconds in the movie mode. Robo 17 emits light.

Incidentally, in the prior art, only the amount of charge C indicated by double hatching in the figure was accumulated.

When the still image mode is canceled and the video mode is changed again, the aperture opening in the most recent video mode is retained during the still image mode, and the aperture opening is now appropriate for video recording. Good continuity can be ensured.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, when shooting a still image, it is possible to secure the same amount of light using strobe light as when shooting a moving image corresponding to the shutter speed of the electronic camera. This makes it possible to obtain good still images with sufficient brightness.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram conceptually showing charges accumulated in an image sensor, and FIG.
The figure is an explanatory diagram for explaining the principle of the electronic shutter, and FIG. 4 is a waveform diagram showing the timing of the electronic shutter operation. In the drawing, 1.10 is a switch, 2 is a system controller, 4 is an image sensor, 14 is an AE control section, 17 is a strobe, and 19 is a flash light receiving element. Patent application for ivy Agent Fuji Photo Film Co., Ltd.

Claims (1)

[Claims] By selecting the video mode, you can shoot a video, which is video information that is read and recorded from the image sensor at regular intervals, and by selecting the still image mode, the electronic shutter of the image sensor is driven, allowing you to capture images at any time. In a video camera system that has an electronic shutter that can take a still image, which is video information that is read out and recorded in a still image mode, there is a light emitting source that operates in a frame or field in still image mode to emit a flash, and a light reflected from the subject. and a light receiving element that receives light, and an electronic shutter is controlled so that the amount of light incident on the image sensor reaches a predetermined amount based on the reflected light received by the light receiving element as the light emitting source emits light. video camera system.