JPH02150179A - Image pickup device - Google Patents

Abstract

PURPOSE:To prevent an iris from being in a small diaphragmed condition by deciding whether an object is inside or outside a room based on the color temperature, illuminance and luminance of an object, and automatically switching a shutter speed. CONSTITUTION:When the output of a B sensor 11 is larger and higher color temperature than the output of an R sensor 10 by respective constant value or more, the object is decided to be outside the room, and in the other cases, it is decided to be inside the room. According to a decision result, a shutter mode switching signal is automatically outputted by a shutter mode switching circuit 9, and it is inputted to a driving circuit 8. Here, the driving pulse conforming to the mode is outputted here, and the electronic shutter speed (charge accumulating time) of an image pickup element 2 is changed. Thus, when the object is decided to be outside the room, by shortening the shutter speed (charge accumulating time), an incident light quantity is reduced, and the small-diaphragmed condition is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is applicable to imaging devices such as video cameras and still video cameras.

[Conventional technology]

Conventionally, in imaging devices, when the iris is used outdoors at a small aperture, the resolution deteriorates due to the phenomenon of light diffraction.
ity) A filter is inserted to prevent the aperture from becoming small.

It is also equipped with a color temperature sensor, which is used for color temperature correction, and enables high-speed shooting by manually switching the shutter speed of the imaging device.

[Problems to be solved by the invention] However, in the conventional example, when the iris becomes a small aperture, the ND filter is moved to the surface of the iris, resulting in hunting of the iris, poor blurring of the lens, and a mechanism for inserting the ND filter. There were problems such as complexity and increased cost due to the provision of an ND filter.

The present invention was made in order to solve these problems, and an object of the present invention is to provide an imaging device that does not need to be equipped with an ND filter.

[Means to solve the problem]

In order to achieve the above object, the present invention configures an imaging device as shown in (1) and (2) below.

(1) A color temperature detection means for detecting the color temperature of the subject; a determination means for determining whether the subject is indoors or outdoors according to the output of the color temperature detection means; and a switching means for switching the shutter speed.

(2) A detection means for detecting the illuminance or brightness of the object; a judgment means for determining whether the object is indoors or outdoors according to the output of the detection means; A switching means for switching the shutter speed is provided.

[Effect]

With the configurations (1) and (2) above, the device itself determines whether the subject is indoors and automatically switches the shutter speed based on the result, making it unnecessary to always have an ND filter.

(Example〕 Hereinafter, the present invention will be explained with reference to Examples.

FIG. 1 is a block diagram showing the configuration of a "Wi image device" which is a first embodiment of the present invention. In the figure, l is an optical system lens, 2 is an image sensor, 3 is an amplifier circuit, 4 is an auto iris control (AE) circuit, an auto gain control (AGC) circuit, and a γ correction circuit, and 5 is a signal that passes through each of the above circuits. 6 is a modulation circuit that modulates the color signal; 7 is a mixing circuit that mixes the modulated color signal and the γ-corrected luminance signal (Y); 8 is a drive circuit that drives the image sensor, 9 is a shutter mode switching circuit, 10.11 is an R sensor,
B sensor, 12.13 is R logarithmic amplifier, B logarithmic amplifier,
14 is a subtraction circuit, and 15 is a comparator.

In the above configuration, an optical signal (imaging signal) from the subject passes through the lens 1 and reaches the image sensor 2, where it is photoelectrically converted. The imaging signal converted into an electric signal is amplified by an amplifier circuit 3 and then passes through an auto iris control, auto gain control, and γ correction circuit 4. Thereafter, the imaging signal is separated into a luminance signal (Y) and a color signal (C), and the color signal passes through a color difference processing circuit 5, becomes a modulation signal in a modulation circuit 6, and is inputted to a mixing circuit 7. Here, it is mixed with the separated luminance signal, and a video signal is output from this mixing circuit 7. This video signal is obtained by automatically determining indoors and outdoors using a sensor that detects color temperature, and automatically switching the shutter speed (i.e., charge accumulation time) of the image sensor 2.

In the figure, 10.11 is R of the light receiving optical system different from the imaging optical system.
A sensor and a B sensor detect the color temperature of an R (red) signal and a B (blue) signal, respectively.

The detection signals of these sensors 10 and 11 are logarithmically amplified by logarithmic amplifiers 12 and 13, respectively, and then input to a subtraction circuit 14, where they are subtracted. This subtracted signal is further input to the comparator 15, where it is compared with a signal of a predetermined amplitude to determine whether the imaging can be conducted indoors or the imaging can be conducted outdoors. That is, when the output of the B sensor is greater than the output of the R sensor by a certain value -F and has a high color temperature, it is determined that the room is outdoors, and otherwise, it is determined that the room is indoors. Then, according to the determination result, the shutter mode switching circuit 9 automatically outputs a five shutter mode switching signal, which is manually input to the drive circuit 8. Then, a drive pulse suitable for that mode is output, and the speed (charge accumulation time) of the electronic shutter of the image sensor 2 is changed.

Specifically, a video signal is outputted at a shutter speed (charge accumulation time) of 1/60 seconds indoors, and at a shutter speed (charge accumulation time) of 1/250 seconds outdoors. In other words, when it is determined that it is outdoors, the amount of incident light is reduced by shortening the shutter speed (charge accumulation time). Just like when it was inserted, you can prevent the aperture from becoming small.

In the first embodiment, the R sensor and the B sensor are provided in a light receiving optical system separate from the imaging optical system, but measures to prevent hunting, such as making a determination only at the start, are taken to You can also use the output of

FIG. 2 is a block diagram showing the configuration of an "imaging device" that is a second embodiment of the present invention.

In the figure, numerals 1 to 9 have the same structure as in FIG.

16 is a brightness determination circuit. In the above configuration, as in FIG. 1, the optical signal from the subject is converted into an electrical signal and amplified by the amplifier circuit 3. Then, the brightness determination circuit 16 uses the output signal to determine whether the subject is outdoors or indoors depending on whether the subject is high brightness (high illuminance) or low brightness (low illuminance), and the shutter mode is automatically set based on the determination result. The switching circuit 9 switches the mode, and the drive circuit 8 changes the electronic shutter speed (i.e. charge accumulation time) of the image sensor.

Specifically, the image sensor itself that outputs the video signal,
It determines high brightness and low brightness, and when the brightness is high, the shutter speed is set to 1/250 seconds assuming the subject is outside, and when the brightness is low, the shutter speed is set to l/60, assuming the subject is indoors.
Automatically switches to a shutter speed of seconds and outputs a video signal. As a result, it is possible to prevent the diaphragm from becoming small when an ND filter is conventionally inserted in the front part of the iris outdoors (at high brightness or high illuminance).

In each of the above embodiments, the shutter speed (charge accumulation time) is switched in two stages for indoor and outdoor settings, but it is also possible to switch it to three or more stages, such as two stages for outdoors. be.

Further, the shutter speed can also be set arbitrarily.

Further, although the speed of the electronic shutter is changed, it is of course possible to change the shutter speed in an apparatus having a mechanical shutter.

(Effects of the Invention) As explained above, according to the present invention, it is determined whether the subject is indoors or outdoors based on the color temperature, illuminance, or brightness of the subject, and the shutter speed is automatically switched. , it is possible to prevent the iris from being in a small aperture state, and it is possible to eliminate the conventional ND filter.

This makes it possible to solve problems such as hunting of the iris caused by the use of an ND filter, poor blurring of the lens, complexity of the mechanism for inserting the ND filter, and increased cost due to constant provision of the ND filter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a first embodiment of the invention, and FIG. 2 is a block diagram of a second embodiment of the invention. In the figure, 2 is an image sensor, 8 is a drive circuit, 9 is a shutter mode switching circuit, 10 is an R sensor, 11 is a B sensor, 1
2.13 is a logarithmic amplifier, 14 is a subtracter, 15 is a comparator,
16 is a brightness determination circuit.

Claims (2)

[Claims] (1) A color temperature detection means for detecting the color temperature of the subject; a determination means for determining whether the subject is indoors or outdoors according to the output of the color temperature detection means; and switching means for switching the shutter speed. (2) A detection means for detecting the illuminance or brightness of the subject, a determination means for determining whether the subject is indoors or outdoors according to the output of the detection means, and a shutter speed according to the output of the determination means. An imaging device comprising: switching means for switching.