JPH0470277A - Image pickup device - Google Patents

Abstract

PURPOSE:To correct the signal level of an image pickup signal, and to improve operation convenience by controlling an iris diaphragm, shutter speed, and the gain of a variable gain amplification circuit on the basis of the quantity of incident light and a prescribed control pattern. CONSTITUTION:By operating an inverse calculation of the quantity of incident light from the signal level of the image pickup signal, and controlling the aperture of the iris diaphragm, the shutter speed of an image pickup element, and the gain of the variable gain amplification circuit from the quantity of incident light and the control pattern, the aperture of the iris diaphragm, the shutter speed of the image pickup element 4, and the gain of the variable gain amplification circuit 12 can be controlled by a control circuit 4 so that the shutter speed a user desires is prior, and thus, the operation convenience of a television camera can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an imaging device, and is suitable for application to, for example, a television camera.

B. Summary of the Invention The present invention provides an imaging device that back-calculates the amount of incident light and controls the opening amount of the diaphragm, the shutter speed, and the gain of the variable gain amplification circuit from the back-calculation result and a preset control pattern. The usability of the television camera can be improved.

C. Prior Art Conventionally, in television cameras, the aperture, the charge accumulation time of the image sensor, and the gain of the variable gain amplifier circuit are controlled.
The brightness of the captured image is controlled B.

That is, as shown in FIG. 6, in the television camera 1, an image of a subject is formed on the imaging surface of the image sensor 4 via the lens 2.

At this time, the image sensor 4 is configured to be able to switch the charge accumulation time based on the control signal output from the timing generator 6, thereby allowing imaging to be performed at a shutter speed desired by the user.

The comparison circuit 8 detects the signal level of the image signal S output from the image sensor 4 with reference to the reference voltage output from a predetermined reference power source 10, and adjusts the aperture of the lens 2 based on the detection result. Control.

Accordingly, in the television camera 1, the signal level of the image pickup signal S is maintained at a predetermined signal level even when the shutter speed is changed by controlling the aperture amount of the aperture.

The variable gain amplifier circuit 12 amplifies the imaging signal S with a predetermined gain and outputs the amplified signal S.

The comparison circuit 14 detects the signal level of the output signal output from the variable gain amplifier circuit 12 with reference to the reference voltage output from a predetermined reference power supply 16, and based on the detection result, the comparison circuit 14 detects the signal level of the output signal output from the variable gain amplifier circuit 12. 12 gains are controlled.

Thereby, for example, when the signal level of the image pickup signal S cannot be maintained at a predetermined level even if the aperture is fully opened because the brightness of the subject is dark, the gain of the variable gain amplifier circuit 12 is switched to a large value.

Thus, in the television camera 1, the signal level of the image pickup signal SS is corrected to a predetermined signal level by switching the gain of the variable gain amplifier circuit 12 in a range that cannot be corrected by the aperture.

Thereby, the output signal output from the variable gain amplifier circuit 12 is converted into a video signal Sv by the signal processing circuit 18 and outputted, thereby obtaining a captured image maintained at a predetermined brightness. .

Problem to be Solved by the Invention By the way, in this type of television camera, it would be possible to control the brightness of the captured image by giving priority to the aperture or shutter speed, like a single-lens camera. , it is considered to be convenient and improve user-friendliness.

The present invention has been made in consideration of the above points, and aims to propose a television camera that can improve user-friendliness.

E Means for Solving the Problems In order to solve the problems, the present invention includes a signal level detection circuit 22 for detecting the signal level of the image pickup signal S output from the image pickup device 4, and a signal level detection circuit 22 for detecting the signal level of the image pickup signal S output from the image pickup device 4; An optical system 2 that forms an image of a subject, an aperture (2) that limits the amount of incident light that enters the image sensor 4 via the optical system 2, and a shutter speed switching means 28 that switches the charge accumulation time of the image sensor 4. , a variable gain amplification circuit 12 that amplifies the imaging signal Ss with a predetermined gain, an incident light amount detection means 24 that detects the amount of light incident on the optical system 2 based on the detection result of the signal level detection circuit 22, and The aperture of the diaphragm (2) and the image sensor 4 are determined from the preset control pattern.
A signal level correction means 24 is provided for controlling the charge accumulation time of , the gain of the variable gain amplification circuit 12, and maintaining the signal level of the image pickup signal S output from the variable gain amplification circuit 12 at a predetermined level.

Based on the detection result of the F action signal level detection circuit 22, the amount of light incident on the optical system 2 is detected, and based on the amount of incident light, the aperture amount of the diaphragm (2) and the aperture amount of the image sensor 4 are determined from a preset control pattern. By controlling the charge accumulation time and the gain of the variable gain amplification circuit 12, a control pattern can be selected as necessary.
It is possible to control the shutter speed or aperture with priority.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, in which parts corresponding to those in FIG. 6 are given the same reference numerals, 20 indicates a television camera as a whole, and the output signal of the variable gain amplifier circuit 12 is input to the detection circuit 22, and the output signal of the output signal is Detect signal level.

The control circuit 24 outputs control signals Sc+, Scm, and S- to the lens 2, the timing generator 28, and the variable gain amplifier circuit 12, respectively, and controls the aperture amount of the aperture, the shutter speed, and the gain of the variable gain amplifier circuit 12.

Further, the control circuit 24 outputs control signals SCI, SCZ and S
When outputting C3, the system desired by the user is achieved by executing the processing procedure shown in FIG. 2 in response to the ON operation of the operators 26A, 26B, and 26C. The opening amount of the diaphragm, the shutter speed, and the gain of the variable gain amplification circuit 12 are controlled in each turn.

That is, the control circuit 24 moves from step SP1 to step SP2, and after taking in the detection results of the detection circuit 22, controls the aperture opening amount, the shutter speed, and the variable gain amplifier circuit 1.
The amount of incident light is calculated backward from the gain of 2.

Subsequently, the control circuit 24 moves to step SP3, and detects the necessary aperture amount of the diaphragm, shutter speed, and gain of the variable gain amplifier circuit 12 based on the detected amount of incident light according to a preset control pattern.

Furthermore, the control circuit 24 moves to step SP4 and prevents the previously set aperture etc. from changing suddenly.
After correcting the detected control amount, the process moves to step SP5.
Here, control signals S62, Set and SCS are output,
Aperture opening amount, shutter speed and variable gain amplifier circuit 12
Set the gain to a value determined by the corrected control amount.

That is, when the portrait mode operator 26A is turned on in advance, the control circuit 24 detects the aperture opening amount, the shutter speed, and the gain of the variable gain amplifier circuit 12 based on the control pattern shown in FIG. do.

Here, in the portrait mode, when the amount of incident light increases, the control circuit 24 first controls the variable gain amplifier circuit 1
The gain of 2 is controlled to be small, thereby obtaining a captured image with a good signal-to-noise ratio.

When the amount of incident light increases further, the shutter speed is increased by 1.
The time is sequentially switched from 760 seconds to 1/100 seconds, thereby reducing flicker in the captured image.

When the amount of incident light increases further, the gain of the variable gain amplifier circuit 12 is controlled to a small value, and then the shutter speed is reduced to 1/1.
00 seconds to 1/2000 seconds, and finally the aperture amount is controlled.

As a result, when the port mode is selected in the television camera, the shutter speed is prioritized over the aperture to obtain a captured image with a shallow depth of focus, thereby blurring the background. It is designed so that a desired subject can be imaged.

On the other hand, when the standard mode operator 26B is turned on in advance, the control circuit 24 controls the aperture opening amount, shutter speed, and variable gain amplifier circuit I2 based on the control pattern shown in FIG. Detect gain.

Here, when the amount of incident light increases, the control circuit 24 first switches the gain of the variable gain amplifier circuit 12 as in the case of portrait mode, and then changes the shutter speed to 1/2.
Switch from 60 seconds to 1/100 seconds sequentially.

When the amount of incident light further increases, the control circuit 24 controls the variable gain amplifier circuit 12 to a state where the gain is the smallest, and then controls the aperture amount of the diaphragm to be small.

Further, the control circuit 24 sequentially switches the shutter speed from 1/100 seconds to 11,500 seconds, and finally controls the opening amount of the aperture.

As a result, in the television camera 1, the aperture opening amount, shutter speed, and gain of the variable gain amplifier circuit 12 are controlled according to the amount of incident light. ing.

On the other hand, when the sports mode operator 26C is turned on in advance, the control circuit 24 controls the aperture opening amount, the shutter speed, and the gain of the variable gain amplifier circuit 12 based on the control pattern shown in FIG. Detect.

Here, when the amount of incident light increases, the control circuit 24 first switches the gain of the variable gain amplifier circuit 12 as in the case of portrait mode, and then changes the shutter speed to 17.
Switch sequentially from 60 seconds to 11500 seconds.

When the amount of incident light further increases, the control circuit 24 controls the variable gain amplifier circuit 12 to the lowest gain state, then controls the aperture opening amount to a smaller value, and finally switches the shutter speed from 11,500 seconds to an even shorter time. .

Thereby, in the television camera 1, the aperture is controlled preferentially to obtain a captured image with a deep depth of focus.

Therefore, the user can use the operator 26A,
By simply turning on 26B and 26C to switch the control pattern, it is possible to easily prioritize the aperture or shutter speed for imaging, thereby improving the usability of the television camera 1.

Thus, in step SP6, the control circuit 24 determines whether or not the stop operator 26D has been turned on, and if a negative result is obtained here, the process returns to step SP2 and repeats the above-mentioned processing procedure, whereby the setting is completed. The brightness of the captured image is controlled using each control pattern.

On the other hand, if a negative result is obtained in step SP6, the control circuit 24 moves to step SP7 and ends the processing procedure.

Thus, in this embodiment, the detection circuit 22 constitutes a signal level detection circuit that detects the signal level of the image pickup signal S output from the image pickup element 4, whereas the timing generator 2 constitutes a signal level detection circuit that detects the signal level of the image pickup signal S output from the image pickup element 4. A shutter speed switching means for switching the accumulation time is configured.

Further, the control circuit 24 constitutes an incident light amount detection means for detecting the amount of light incident on the optical system 2 based on the detection result of the signal level detection circuit, and also forms a control pattern based on a preset control pattern based on the detected amount of incident light. , the aperture of the diaphragm, the charge accumulation time of the image sensor 4, and the gain of the variable gain amplification circuit 12, and output the image signal S from the variable gain amplification circuit 12.

A signal level correction means is configured to maintain the signal level of the signal at a predetermined level. In the above configuration, the image signal S output from the image sensor 4 is amplified by a predetermined gain in the variable gain amplifier circuit 12, and then converted into a video signal Sv by the signal processing circuit 18.

At this time, the imaging signal S output from the variable gain amplifier circuit 12 is detected by the detection circuit 22 to detect the signal level, and the detection result is output to the control circuit 24.

Here, the signal level detection result, the opening amount of the aperture, and the image sensor 4
The amount of light incident on the lens 2 is detected based on the charge accumulation time and the gain of the variable gain amplification circuit 12, and a necessary control amount is detected from the control pattern based on the detection result.

As a result, the aperture of the diaphragm, the shutter speed of the image sensor 4, and the gain of the variable gain amplifier circuit 12 are controlled based on the control am, and the signal level of the image signal S output from the variable gain amplifier circuit 12 is increased. is corrected to a predetermined value, and thus a captured image maintained at a predetermined brightness can be obtained.

Furthermore, at this time, by switching the control pattern, for example, the aperture amount of the diaphragm, the shutter speed of the image sensor 4, and the variable gain amplifier circuit 12 can be changed so that the shutter speed is prioritized.
gain can be controlled, and the usability of the television camera can be improved.

According to the above configuration, the amount of incident light is calculated backward from the signal level of the imaging signal, and the aperture amount of the diaphragm, the shutter speed of the image sensor, and the gain of the variable gain amplifier circuit are controlled from the amount of incident light and the control pattern. The opening amount of the diaphragm, the shutter speed of the side image element, and the gain of the variable gain amplifier circuit can be controlled so that the desired shutter speed is given priority, thereby improving the usability of the television camera. can do.

In addition, in the above-mentioned embodiment, a case was described in which control is performed by switching between three control patterns assigned to portrait mode, standard mode, and sports mode.
The present invention is not limited to this, and various control patterns can be set as necessary.

Furthermore, if the flicker is not noticeable at this time, see Figure 3~
The shutter speed and the gain of the variable gain amplifier circuit may be controlled as shown by the broken line in FIG.

Further, in the above embodiment, the variable gain amplifier circuit 12
Although the case has been described in which the signal level of the imaging signal output from the variable gain amplifier circuit 12 is detected and the amount of incident light is detected based on the detection result, the present invention is not limited to this. The level may also be detected.

In the above embodiment, the present invention was applied to a television camera, but the present invention is not limited to this, but can be widely applied to various imaging devices such as electronic still cameras. .

H Effects of the Invention As described above, according to the present invention, after the amount of incident light is detected by back calculation, the aperture, shutter speed, and gain of the variable gain amplifier circuit are controlled based on the amount of incident light and a predetermined control pattern. As a result, the signal level of the imaging signal can be corrected in a mode desired by the user, and thus an imaging device with improved usability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a television camera according to an embodiment of the present invention, FIG. 2 is a flowchart for explaining its operation, FIGS. 3 to 5 are characteristic curve diagrams for explaining control patterns, and FIG. FIG. 6 is a block diagram showing a conventional television camera. ■, 30... Television camera, 2...
...Lens, 4...Image sensor, 6.28...
...timing generator, 12...variable gain amplifier circuit, 22...detection circuit, 24...
...Control circuit.

Claims (1)

[Claims] A signal level detection circuit that detects the signal level of an imaging signal output from an imaging device; an optical system that forms an image of a subject on an imaging surface of the imaging device; , an aperture that limits the amount of incident light that enters the image sensor, a shutter speed switching means that switches the charge accumulation time of the image sensor, a variable gain amplification circuit that amplifies the image signal with a predetermined gain, and a signal level detection circuit. an incident light amount detection means for detecting the amount of incident light of the optical system based on the detection result of the above; An imaging apparatus comprising: signal level correction means for controlling the gain of the variable gain amplifier circuit and maintaining the signal level of the imaging signal output from the variable gain amplifier circuit at a predetermined level.