JPS59114976A - Video camera - Google Patents

Abstract

PURPOSE:To facilitate easy handling of a video camera with no increment of the size and weight by performing the exposure in a still picture mode after opening an automatic diaphragm with a still signal and then closing the diaphragm again with an exposure time control signal. CONSTITUTION:A program type exposure time control circuit 60 detects a sight out of a subject field to calculate the optimum exposure value and delivers the result of calculation as an exposure time control signal. While a gate circuit 70 supplies both the exposure time control signal and still signal and delivers an automatic diaphragm shutter control signal which controls the open/close of the automatic diaphragm in a still picture shooting mode. This control signal opens and closes an automatic diaphragm 10 through an automatic diaphragm driving circuit 21. The diaphragm 10 is closed for a fixed period of time after the still signal is delivered. Then the diaphrgam 10 is gradually opened for a period during which the exposure is given based on a program after the fixed period elapses. Then the diaphragm 10 is closed again for said exposure time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video camera that uses an automatic aperture as a shutter to take still images at various exposure times.

For example, there is a conventional video camera shown in FIG. 1, in which the lens body L is provided with an automatic aperture lo and an automatic aperture drive circuit 20, and the body body B is provided with an automatic aperture and recording control drive circuit 4o. . In the figure, "automatic aperture" is indicated by A. It is shown as I.

The video camera described above photographs one screen every 1/H second or 1/30 second, and by continuously projecting this photographed screen, it can be viewed as a moving image. Therefore, each of the above screens is a still image.

However, with the conventional video camera mentioned above, it is not possible to take still images with various exposure times. The shutter speed is fixed and it is not possible to take still images at other shutter speeds. Therefore, in order to be able to shoot moving images and still images with various exposure times with a single video camera, it is necessary to create a combination of the above-mentioned conventional video camera and still camera. Conceivable. However, in this case, there are problems in that the overall shape is large, the weight is large, and handling is complicated.

The unreleased model was created by focusing on the above-mentioned problems with the conventional method.It is a video camera that can take still images with various exposure times, and its shape and weight are almost the same as the conventional method. The object of the present invention is to provide a video camera that is easy to handle.

To achieve this purpose, the uninvented, Ming has developed automatic aperture and
A video camera equipped with an automatic aperture drive circuit that drives the automatic aperture includes a still control circuit that outputs a still signal indicating that it is in a still image shooting state, and a programmable exposure time control circuit that outputs an exposure time control signal. , a gate circuit that inputs the exposure time control signal and the still signal and outputs an automatic aperture shutter control signal that controls opening and closing of the automatic aperture during still image shooting, and the automatic aperture is controlled by the still signal. The aperture is opened from the closed state and returned to the closed state by the exposure time control signal to achieve still image exposure, and when shooting the still image, the automatic aperture is automatically adjusted according to the brightness of the subject. It is characterized in that opening and closing operations are performed in a consistent manner.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. Incidentally, the same members as those shown in FIG. 1 are designated by the same reference numerals, and the explanation thereof will be omitted. FIG. 2 is a block diagram showing one embodiment of the present invention. The still control circuit 50 operates for a predetermined period of time after receiving the still trigger signal.
It generates still signals. This still signal is a signal indicating that a still image is being photographed. The programmable exposure time control circuit 60 detects the amount of light from the subject, calculates the optimal exposure at that time, and outputs the result as a signal (exposure time control signal) related to the exposure time of the automatic aperture. It is something. The gate circuit 70 receives the exposure time control signal and the still signal, and outputs an automatic aperture shutter control signal that controls opening and closing of the automatic aperture during still image shooting. This automatic aperture shutter control signal is transmitted to the automatic aperture 10 through the automatic aperture drive circuit 21.
It opens and closes the automatic aperture lO for a predetermined period of time from when the still signal is output, and after that predetermined time has elapsed, the automatic aperture lO closes for the programmed exposure time.
This is a signal that causes the automatic diaphragm 10 to gradually open and close the automatic aperture 10 for a predetermined time after the programmed exposure time has elapsed.

Further, the recording control drive circuit 41 records the imaging signal obtained by opening the automatic diaphragm 10 during still image shooting on a predetermined recording medium as described above, and allows a sufficient time for the recording to be completed. After the elapse of time, a recording completion signal is sent to the still circuit 50.

FIG. 3 is a circuit diagram showing the embodiment shown in FIG. 2 in more detail. A D flip-flop 51 is used as the still circuit 50. Switch to turn on when shooting still images (switch that works with the release button)
The connection point between I and the resistor 2 is connected to the clock terminal of the flip-flop 51. Further, the Q terminal is used as a still signal generation terminal, and the R terminal receives a recording completion signal.

Further, the gate circuit 70 includes an inverter 71 and an AND gate 72. The inverter 71 inverts the exposure time control signal, and the AND gate 72 receives the output signal of the inverter 71 and the methyl signal.

Next, the operation of the above embodiment will be described, using the timing chart shown in FIG. 4. First, when switch l is open, no still signal is generated and AND gate 72 is not output, so
The automatic aperture drive circuit 21 is controlled only by a signal from the automatic aperture control circuit 30, and moving image photography is performed.

Next, when the switch 1 is turned on, a still trigger signal is generated, and thereby a still signal is generated at the Q terminal of the flip-flop 51. Programmable exposure time control circuit 6
0 does not output for a predetermined time Tl after receiving the still signal. Therefore, the inverter 71 outputs an output for the predetermined time T1. Therefore, the automatic aperture shutter control signal is output during the TI, and the automatic aperture control circuit 21 closes the automatic aperture lO during this time T1.

When the T1 time has elapsed, 12 hours from that time,'
Since the R mountain time control circuit 60 outputs, the AND gate 7
The above-mentioned time T2, in which the automatic diaphragm 10 gradually opens from the beginning of 12 hours, is determined according to the amount of light in the field at that time.

After the above-mentioned 12 hours have elapsed, the exposure time control signal disappears, so the automatic aperture shutter control signal is output in the same way as time T1, and that time is designated as T3. During this period, the automatic diaphragm 10 begins to close rapidly and thereafter remains closed during T3. During this time, the video signal related to the still image shooting is recorded on the recording member. When 13 hours have elapsed, a recording completion signal is generated from the recording control drive circuit 41, and in response, the still signal disappears, the still image shooting by the video camera ends, and the video camera starts moving image shooting operation.

That is, the automatic diaphragm 10 is controlled by the automatic diaphragm control circuit 30.

As mentioned above, since the present invention is a video camera that can take still images with various exposure times, its shape and weight can be made almost the same as conventional ones, and it is also suitable for still image shooting. Since switching is done by simply turning on the switch, it has the advantage of being easy to handle.

[Brief explanation of the drawing]

1Q is a block diagram showing a conventional video camera, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a diagram showing the above embodiment in more detail, and FIG. 4 is a block diagram showing the above embodiment. This is a time chart. 10...Automatic aperture, 21...Automatic aperture drive circuit, 5
0... Still control circuit, 60... Program type exposure control circuit, 70... Gate circuit.

Claims (2)

[Claims] (1) In a video camera equipped with an automatic aperture and an automatic aperture drive circuit that drives the automatic aperture, a still control circuit that outputs a still signal indicating a still image shooting state and an exposure time control signal are output. It has a programmable exposure time control circuit, and a gate circuit that inputs the exposure time control signal and the still signal and outputs an automatic aperture shutter control signal that controls opening and closing of an automatic aperture during still image shooting; The automatic diaphragm is opened from the closed state by the still signal, and is returned to the closed state by the exposure time control signal to achieve still image exposure. A video camera characterized in that opening and closing operations are automatically performed according to the brightness of the video camera. (2) The still signal is turned on by a still trigger signal linked to a release button, and turned off by a recording completion signal indicating that image recording on a recording medium has ended. ) Video cameras listed in section 2.