JPS5840982A - Video camera - Google Patents

Abstract

PURPOSE:To improve the operability of a video camera, by showing clearly the area focusing and operating on an image pickup screen which emerges on the cathode-ray tube of an electronic viewfinder. CONSTITUTION:The lihgt made incident to a lens 1 is converted into electric signals through a camera circuit 2, and only the high frequency band part of the electric signal is extracted through a high pass filter 5. Then only the high frequency band part is made to pass via a gate circuit 6 which is actuated by the pulse supplied from a gate pulse generating circuit 9 and undergoes the wave detection through a wave detecting circuit 7 in order to obtain a focused state of only the desired subject. The helicoid position is shifted by a motor 11, and a differential voltage detecting circuit 8 sample-holds the focus voltage. Then a driving circuit 10 turns the motor 11 in accordance with the increase/ decrease of the voltage. The pulse of the circuit 2 is applied to a focusing range specifying signal producing circuit 15. Thus a focusing range specifying signal is delivered to be mixed with the video signal by a mixing circuit 18 after passing through a switch 17 and then fed to an electronic viewfinder 14.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video camera equipped with an automatic focusing device and a finder, in which a focusing range can be displayed on the finder.

As an automatic focusing device that takes advantage of the characteristics of a video camera, it detects the definition of the screen using the high-frequency components of the video signal being shot, and maximizes the definition, that is, the high-frequency components. So-called hill-climbing control is known, which controls the rotation of a distance ring (hereinafter referred to as a helicoid) of a lens. This method is described in detail in the NHK Technical Research Report (1960, Vol. 17, No. 1, vol. 86+!I, p. 21). A brief explanation will be given below using FIGS. 1, 2, and 113.

FIG. 1 is a block diagram showing the configuration of a video camera equipped with a hill-climbing automatic focusing device. In the figure, 1 is a lens, 2 is a camera circuit, 3 is a video signal output terminal, 4 is a focal voltage generation circuit, 5 is a high-pass filter (1 pass filter HPF), 6 is an image frame gate circuit, and 7 8 is a detection circuit, 8 is a differential voltage detection circuit (for example, a differential hold circuit), 9 is an image frame gate pulse generation circuit, 10 is a motor drive circuit, and 11 is a motor for rotating the helicoid of the lens 1. The operation of the circuit in Figure 1 is explained below in the second diagram.
This will be explained using FIG. Note that FIG. 2 is an explanatory diagram of a subject to be focused, and FIG. 3 is a graph showing the relationship between the helicoid position and focal voltage, etc.

In FIG. 1, light from a subject entering a lens 1 forms an image, becomes an IK signal in a camera circuit 2, and is outputted to a terminal 5 as a video signal. Only the high frequency components of this video signal are extracted by the bypass filter 5. In order to focus only on the subject that the photographer is interested in among the subjects imaged here, only the high-frequency components of the image signal within the broken line in FIG. 2 are passed through the image frame gate circuit 6.

A gate pulse for operating the picture frame gate circuit 6 is supplied from a picture frame gate pulse generation circuit 9, and is generated based on the vertical drive (VD) pulse and horizontal drive (HD) pulse from the camera circuit. In other words, if the focal voltage t'' is obtained from the high-frequency components of all the image signals taken, it is likely that a distant object will be in focus and a nearby object will be in focus.
Further, in general, the range to be focused on is often not the entire range on the screen but a certain range. For these reasons, providing the gate circuit 6 is extremely effective in achieving a good focusing operation. The gated high-frequency component is detected and smoothed by a detection circuit 7, and is applied to a terminal 12. The voltage applied to the terminal 12 (the fifth
The curve (a) in the figure (hereinafter referred to as focal voltage) corresponds to the definition of the captured film image, so the curve (a) in the figure corresponds to the definition of the captured movie image, so
If (referred to as A) matches the distance between the lens 1 and the subject, it will be maximum, and as it deviates from this, it will decrease. In Figure 3, the curve (Curve showing the output voltage of the differential voltage detection circuit 8 when the helicoid position is moved from the closest position in the ω direction), (c) is the curve that shows the output voltage of the helicoid position moved from (1) in the closest direction. This is a curve showing the change in the same voltage when

What can be determined from Figure 3 is that if the helicoid position is controlled by some means so that it climbs the mountain of focal voltage, and the helicoid is guided to the top of the mountain where the focal voltage is maximum, automatic focusing can be achieved. It is a vine.

This means is achieved by the differential voltage detection circuit 8 to motor 11 shown in FIG. That is, while moving the helicoid position by the motor 11, the differential voltage detection circuit samples and holds the focal voltage applied to the terminal 12 at fixed time intervals.
This is a circuit that generates a positive voltage if the focal voltage is increasing over time, and a negative voltage if it is decreasing).
If the output voltage of the differential voltage detection circuit 8 applied to the terminal 16 is positive, the motor drive circuit 10 keeps the rotational direction of the motor 11 as it is and continues climbing the mountain nine more times, and if the same output voltage is negative, the motor 11 Reverse and return the helicoid to the direction up the mountain.

In this way, the helicoid position control closed loop with the configuration shown in FIG. To reach the steady state mK while vibrating to K
Focusing can be done automatically. The above is an automatic focusing device for a video camera based on the Yamato 9 method.

This method uses the camera itself to perform focusing operations, and has a simpler structure, requires fewer initial adjustments, and is cheaper than a method that measures distance using an independent distance measuring mechanism and controls the helicoid position in a closed loop based on the results. A pressure-accurate automatic focusing device can be constructed.

Reference numeral 14 in FIG. 1 is an electronic P-finder through which the photographer observes the imaging range of the subject, and generally a black and white video monitor with a 1.5-degree resolution is added as one function of the video camera. The above is the configuration of a video camera equipped with a mountain climbing automatic focusing device that extracts high-frequency components from video signals, but in this case, the photographer captures images while viewing the subject with an electronic viewfinder What part of the subject is automatically focused on, and where in the electronic viewfinder should the photographer place the subject to focus on? Not necessarily good. In addition, when a manual/automatic switch is installed so that focusing can be performed manually, it is difficult to judge whether manual or automatic focusing is currently being performed by simply looking at the -child and -viewfinder. The object of the present invention is to eliminate the disadvantages of the prior art described above and to provide a video camera equipped with an automatic focusing device that is easy to operate.

The gist of the present invention is to improve operability by clearly indicating the part that is being focused on the image pickup screen on the display tube of the electronic viewfinder. More specifically, only the high-frequency components of the portion of the video signal to be focused are passed through the image frame gate circuit 6, and the focus voltage is obtained from the passed high-frequency components to achieve focusing. A focusing range clarifying signal is generated in synchronization with an image frame gate pulse applied to a gate circuit, and this signal is mixed with a video signal and input to an electronic beehive finder.

Next, an embodiment of the present invention will be described with reference to the drawings. Figure 4 is a professional diagram showing one embodiment of the present invention, and Figure 5 is a diagram showing an embodiment of the present invention.
FIG. 4 is an explanatory diagram of a display mode of a focusing range displayed on the be-finder according to FIG.

In FIG. 4, numerals 1 to 14 are the programs having the same functions as those shown in FIG. 1 with the same numbers. Reference numeral 15 denotes a focusing range clarifying signal generation circuit for vertically driving the camera circuit 2 (V
D) A horizontal drive (HD) pulse is applied, and a focusing range clarifying signal synchronized with the image frame gate pulse generated by the image frame gate pulse generation circuit 9 is obtained at the terminal 19;
Switch F 17K passes through mixing circuit 18 by terminal 6
The electronic and m-finder 14 are mixed with the video signal from
is input. During automatic focusing operation, the switch 1619 is closed and the focus range is displayed on the screen of the Naruko PyuFinder according to the type of focus range clarifying signal obtained by the circuit 15, as shown in FIG. a) White border, (b
You can create a filmed image with a clear focus range, such as () black spots, (,) sinking in the dot direction, and (d) fading in the white direction. In addition, when performing the focusing operation manually, it is sufficient to open the switch 16.19. In this case, the focus range indication 11@ is not supplied to the electronic P-finder, so the image becomes a normal photographed image, and the automatic focusing operation is in progress. You can immediately tell that it is not.

As explained above, according to one aspect of the present invention, when a viewer captures an image while viewing the subject with an electronic viewfinder,
During the automatic focusing operation, if the subject is photographed so that the subject to be focused is within the specified focus range, it is easy to take a good photograph according to the photographer's purpose. Furthermore, since the focusing range is not clearly displayed during manual focusing, it is possible to quickly determine that manual focusing is in progress. As described above, according to the present invention, the operability of a video camera equipped with an automatic focusing operation device is improved and becomes a friend, and it is possible to film or film and record good damage.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of a video camera equipped with an automatic focusing device using the Yamatoshi method, Figure 11112 is an explanatory diagram of the subject to be focused on, and Figure 3 is a diagram showing the helicoid position, focal voltage, etc. 94 is a block diagram showing an embodiment of the present invention, and FIG. 5 is an explanatory diagram of the display mode of the focusing range displayed in the finder according to the present invention. Description of symbols 1... Lens, 2... Camera circuit, 4... Focus voltage generation circuit, 5... High pass filter, 6... Image frame gate circuit, 7... Detection circuit, 8... ... Differential voltage detection circuit, 9 ... Image frame gate pulse generation circuit, 10 ... Motor electric circuit, 11 ... Motor, 14 ... Electronic 5 pin,
-Finder, 15...Focusing range clarifying signal generation circuit,
16.17...Focusing operation automatic, manual changeover switch, 1
8... Mixed circuit. 1st mouth 2nd Nagi 3rd fang

Claims (1)

[Scope of Claims] 1) A camera circuit that converts an optical image of a subject formed by an optical lens system into a video signal and outputs the converted image; and a camera circuit that converts and outputs an optical image of a subject formed by an optical lens system; A picture frame designation signal generation circuit generates a picture frame designation signal based on vertical drive pulses and horizontal drive pulses in the circuit, and a high frequency video signal within the picture frame among the video signals from the camera circuit given the picture frame designation signal. A circuit that extracts only the component, detects an increase or decrease in the focal voltage obtained by detecting and rectifying the extracted high-frequency component, and detects an increase or decrease in the focal voltage obtained by detecting and rectifying the extracted high-frequency component, and then the optical lens is connected so that the high-frequency component becomes moth-sized. In a video camera equipped with a drive means for driving a system to enable automatic focusing on a subject, when a video signal is input and the composition of the subject is monitored, the vertical drive pulse and horizontal and a circuit for creating a focusing range clarifying signal that specifies a certain image frame range to be focused by a driving pulse, and inputting the mixture of the focusing range clarifying signal and the video signal to the viewfinder. C,
- A video camera characterized in that the focusing range is clearly displayed on the screen of the finder. 2. In the video camera according to claim 1, when switching from automatic focusing operation to manual focusing operation, the switching is performed in conjunction so that the focusing range explicit signal is not input to the viewfinder. Features a video camera.