JPH02197823A - Imaging device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an imaging device such as a television camera or a video camera. The present invention relates to an imaging device in which the shutter speed of the imaging means is changed in conjunction with the aperture control, thereby substantially expanding the dynamic range of the aperture control.

(Prior Art) Conventionally, when photographing a subject with high brightness using an imaging device such as a television camera, an appropriate exposure amount may be obtained when the aperture value of the photographing system is at the maximum aperture value or a value close to close. In such a case, insert an ND filter installed in the imaging device into a predetermined position in the imaging system to essentially reduce the aperture value and shift the aperture operating range from the maximum aperture value to a smaller aperture value. A method of photographing is adopted. However, an imaging device in which an ND filter is inserted into the imaging system has a problem with the imaging technique. For example, when shooting for news coverage, moving from indoors where there are many low-brightness subjects to outdoors where there are many high-brightness subjects, the camera will be overexposed, causing so-called "henching" in which the aperture goes back and forth between maximum aperture and close. , there were problems such as not being able to take good pictures.

(Problems to be Solved by the Invention) The present invention provides an imaging apparatus such as a television camera that uses an imaging means such as a COD having an electric shutter function. By providing a shutter speed control circuit that has the function of controlling or selecting the shutter speed of the aperture control i! It is an object of the present invention to provide an imaging device that can substantially expand the field of view and easily obtain an appropriate exposure amount for a subject in a wide luminance range from a low-luminance subject to a high-luminance subject.

(Means for Solving the Problems) An imaging system having an auto-iris circuit for controlling the aperture diameter of an aperture provided in the imaging system, and an imaging means equipped with a shutter function for forming a subject image by the imaging system. In the apparatus, a detection circuit detects the maximum and minimum values of the aperture value from a signal from the auto-iris circuit or a signal based on the aperture aperture of the aperture, and a shutter of the imaging means using the output signal from the detection circuit. It also has a shutter speed control circuit that controls the speed. In particular, the present invention configures the shutter speed control circuit and the auto iris circuit independently.

It is characterized in that the shutter speed in the shutter speed control circuit is selected by manual instructions from the shutter speed operation section.

(Embodiment) FIG. 1 is a block schematic diagram of an embodiment in which the present invention is applied to an imaging device for a television camera.

In the same area, l is a photographing system and has an aperture la.

2 is a three primary color separation prism; 3 is an imaging means; imaging plates 3a, 3b, such as CCDs, arranged on the exit surface of the three primary color separation prism 2 and having electrical shutter functions corresponding to red, green, and blue;

It consists of 3C. 4 is an amplifier circuit, which includes video amplifiers 4a corresponding to the three primary color imaging plates 3m, 3b, and 3c, respectively;
It consists of 4b and 4c.

An encoder 5 converts the output signals from the video amplifiers 4a, 4b, and 4C into predetermined signals.

Reference numeral 12 denotes an iris control circuit which controls the aperture of the diaphragm la. Reference numeral 6 denotes an auto-iris circuit, which uses the output signal from the amplifier circuit 4 to send a predetermined aperture value signal to the iris control circuit 12. Reference numeral 7 denotes a detection circuit, which is comprised of a small F-number detection circuit 7a for detecting the minimum aperture value and a maximum F-number detection circuit 7b for detecting the maximum aperture value. A shutter speed control circuit 8 controls the shutter speed of the imaging means 3 automatically and manually. Reference numeral 9 denotes a changeover switch which, when setting the shutter speed to Mal, switches between a mode in which control is performed in conjunction with the auto iris and a mode in which the shutter speed is manually selected. Reference numeral 10 denotes a manual selection section, which is comprised of 1 mode for manually selecting the shutter speed of the imaging means 3;

Reference numeral 11 denotes a drive circuit that drives and controls the imaging means 3.

In this embodiment, the light flux from the object that has passed through the photographing system 1 is separated into three color lights by the three primary color separation prism 2 and enters the image pickup plates 3a, 3b, and 3C of the image pickup means 3, respectively. Electrical signals related to the subject image outputted from the imaging means 3 are amplified by video amplifiers 4a, 4b, and 4c of an amplifier circuit 4, respectively, and then inputted to an encoder 5 and an auto-iris circuit 6. Of these, the auto iris circuit 6 outputs an auto iris signal, and this signal is input to the minimum F value detection circuit 7a and the maximum F value detection circuit 7b.
In step b, the input signal is compared with the signal of the F number, which is each aperture value to be detected, arbitrarily set in advance by the aperture operation unit, and when they match, the F number detection signal is output. The shutter speed control circuit 8 is set to the circuit 7a when the changeover switch 9 is in the auto iris linked shutter speed control mode.
And the output signal of circuit 7b is input and it operates.

2 to 5 illustrate the operation of the shutter speed control circuit 8 at this time.

The horizontal axes in FIGS. 2 to 5 are all time axes and indicate the same time. In Figure 2, straight line A indicates the signal level at the open end of the diaphragm, straight line B indicated by a dotted line indicates the signal level at the minimum value of the detected F value, and curve C indicates the auto iris signal.
A straight line indicated by a dotted line indicates the signal level of the maximum value of the detected F value, and a straight line E indicates a signal indicating the aperture end of the diaphragm. In FIG. 3, F represents the output signal from the minimum F value detection circuit 7a, in FIG. N44, G represents the output signal from the maximum F value detection circuit 7b, and in FIG. 5, H represents the shutter speed. When the amount of exposure incident on the imaging means 3 is large, the auto iris signal C shifts to the aperture end side E, and when it matches the signal level D which is the maximum value of the F value (time tl), the maximum Fm is reached as shown in figure gg4. The detection circuit 7b outputs an F value detection pulse, and the shutter speed control circuit 8 detecting this output pulse shifts the shutter speed to a faster side, and the auto iris signal C shifts to the open side. When the exposure amount at this time is large, the auto iris signal C shifts again to the aperture end side E, and when it matches the signal level D which is the maximum value of the F value (time t2), the maximum F value detection circuit 7b again outputs the F value detection pulse. is output, the shutter speed control circuit 8 shifts the shutter speed to the faster side, and the auto iris signal C shifts to the open side. Next, when the exposure amount becomes small, the A-door iris signal C shifts to the open side, and when it matches the signal level B which is the minimum value of the F value (time t3), the minimum F (a detection circuit 7a is shown in FIG. 3). Output the F value detection pulse as shown,
The shutter speed control circuit 8 detecting this output pulse shifts the shutter speed to a slower side, and the auto iris signal C shifts to the aperture end side E. In the mode in which the changeover switch 9 manually selects the shutter speed, the shutter speed control circuit and auto iris circuit are disconnected, and in this case, the shutter speed output signal given by the manual selection section 10 is input to the shutter speed control circuit 8. Based on the input signal obtained, the shutter speed control signal H is sent to the drive circuit 1 of the imaging means 3.
It is output to 1.

In this way, in this embodiment, the amount of exposure incident on the imaging means is appropriately controlled by automatically or manually controlling the shutter speed of the imaging means using a signal related to the aperture value of the aperture disposed in the photographing system. This makes it easy to obtain good images for subjects with a wide brightness range.

(Effects of the Invention) The imaging device of the present invention is capable of (a) photographing with proper exposure even when the brightness of the subject changes greatly, such as when photographing while moving from indoors to outdoors, and it is possible to insert and remove an ND filter; It is possible to achieve an imaging device that eliminates cumbersome operations and the like.

(b) FIG. 6 is an example showing the relationship between the brightness of the subject and the F value of the aperture when the shutter speed is automatically controlled in the present invention. As shown in the figure, the minimum detection F
By setting the aperture value and maximum detection F value, the aperture can be fixed within a certain range, so by setting the detection level to a certain F value, it is possible to take images that take into account the depth of focus of the wired aperture. .

(c) Normally, in television cameras and the like, the optical performance of the photographing system is set to be best within the range of F-number of about 5.6 to 8. Therefore, by setting the F-number detection level within the above range, it is possible to always take good pictures.

It has the following features.

[Brief explanation of the drawing]

Figure 1 is a block schematic diagram of an embodiment when the invention is applied to an imaging device of a television camera, Figure N42 is a diagram of the auto iris signal '11, and Figure 3 is a diagram of the output signal from the minimum F value detection circuit. The explanatory diagram, Diagram N44, is an explanatory diagram of the output signal from the maximum F value detection circuit, Diagram N16 is an explanatory diagram of changes in shutter speed, and FIG. 6 is an explanatory diagram showing the relationship between the brightness of the subject and the F value. In the figure, 1 is the photographing system, 1a is the aperture, 2 is the three-color separation prism,
3 is an imaging means, 4 is an amplifier circuit, 5 is an encoder, 6 is an auto iris circuit, 7 is a detection circuit, 8 is a shutter beat control circuit, 9 is a changeover switch, 10 is a manual operation unit, and 11 is a drive circuit. , 12 is an iris control circuit.

Claims (3)

[Claims] (1) In an imaging device having an auto-iris circuit for controlling the aperture diameter of an aperture provided in the imaging system, and an imaging means equipped with a shutter function for forming a subject image by the imaging system, from the auto-iris circuit. or a signal based on the aperture of the diaphragm, a detection circuit that detects the maximum and minimum values of the aperture value, and a shutter speed control that controls the shutter speed of the imaging means using the output signal from the detection circuit. An imaging device comprising: a circuit. (2) The shutter speed control circuit and the auto iris circuit are configured independently, and the shutter speed in the shutter speed control circuit is selected by a manual instruction from a shutter speed operation section. imaging device. (3) The imaging apparatus according to claim 1, wherein the maximum and minimum aperture values of the aperture are set by manual instructions from an aperture operation section.