JP3310280B2 - camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a camera, and more particularly, to a camera having illumination means for illuminating a subject.

2. Description of the Related Art In a camera such as a studio TV camera, a home video camera, an electronic camera, or a camera-integrated VTR, when photographing a low-illuminance subject, the amount of reflected light from the subject is insufficient. Illumination means such as movie lights are used to compensate.

In this case, the camera's auto white balance (hereinafter, referred to as “auto white balance”)
The control (abbreviated as AWB) is performed independently of the lighting means. Then, the light from the illumination means is received by the AWB sensor,
After the color temperature is calculated and gain is increased, the white balance is controlled.

[0004] Here, a general description of the color temperature will be given with reference to FIG. 3. In the case of an incandescent lamp, the temperature is 2800 to 3200 ° K, in the case of a fluorescent lamp, it is 4500 to 4700 ° K, and In the case of light, it is more than 5800 ゜ K. A movie light used as a lighting device of a normal camera emits light with a color temperature close to that of sunlight. However, depending on the type of light, a light with a color temperature corresponding to the intended use is emitted.

[Problems to be Solved by the Invention] However, in a camera having a conventional lighting unit,
Since the white balance is controlled irrespective of the illuminating means, a deviation in the white balance when using the light cannot be avoided. This will be described with reference to FIG. 4. A person 33 located in the foreground with mountains 31 and trees 32 located in a distant view in the background.
If you try to shoot while irradiating with the lighting means, there is a limit to the amount of light emitted by the lighting means.
Does not reach the target, and only the person 33 in the foreground is irradiated. At this time, if the white balance control is performed only on the camera side as in the related art, the white balance control is performed in consideration of the white balance information of the distant view. Therefore, when the color temperature of the person 33 in the near view is different from the color temperature of the mountain 31 or the tree 32 in the distant view, the face of the person 33 as the main subject becomes unnatural.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to provide an optimal white balance to a main subject to be illuminated and illuminated by illumination means, and to provide a distant view in which illumination light from the illumination means does not reach. Another object of the present invention is to provide a camera capable of performing an appropriate white balance even for a subject located in the camera.

[Means and Actions for Solving the Problems] A camera according to the present invention includes an illuminating unit capable of continuously irradiating a subject with light, a feeding unit for feeding power to the illuminating unit, and the feeding unit. An electric quantity detecting means for detecting an electric quantity supplied to the lighting means, and an automatic white balance detecting means for detecting color temperature information of the subject,
White balance control means for controlling a white balance based on the output from the automatic white balance detection means and the electric quantity detected by the electric quantity detection means.

Hereinafter, the present invention will be described in detail with reference to the drawings. First, before describing an embodiment of the present invention, a basic concept of the present invention will be described with reference to FIG.

FIG. 2 is a diagram in which the horizontal axis plots the amount of electricity supplied to the movie light 12 and the vertical axis plots the color temperature of irradiation light emitted from the movie light as illumination means. . As is clear from the figure, the color temperature of the light emitted from the movie light is proportional to the amount of electricity, such as current, voltage, or power supplied to the light. Therefore, by using the characteristics shown in FIG. 2, the color temperature information of the irradiation light can be converted into a signal of an electric quantity such as a voltage or a current, and the white balance circuit system can be directly controlled. In this case, the amount of electricity supplied to the movie light is detected by a current control circuit 13, which will be described later, and converted into a voltage value and a current value of a white balance system by a CPU 9 and fed back to a video signal circuit system. We try to bring the balance to an appropriate value.

In this case, the following two feedback systems can be considered. (A) Control is performed only by changing the amount of electricity supplied to the movie light. In other words, in FIG. 4, the control is performed only by the color temperature of the area directly irradiated by the movie light, such as the person 33. thing.

(B) In addition to the above-mentioned means (a) for controlling only by a change in the amount of electricity supplied to the movie light, conventional means for performing signal processing on a sensor signal from an AWB sensor is mixed and controlled.

The means (A) can reproduce an image whose white balance is completely controlled with respect to the person 33 in FIG. In other words, since the white balance is not obtained, an uncomfortable feeling is caused.

On the other hand, in the means (b), since the white balance of the distant view information is adjusted to some extent, it is possible to perform white balance control that does not greatly deviate from any of a subject at a short distance and a distance. Therefore, in the embodiment described below, a description will be given of a circuit using the means shown in (b). The present invention can be widely applied to a TV camera for a studio, a home video camera, an electronic camera, and the like. In this embodiment, a camera-integrated VTR shown in FIG. 1 will be described as an example.

The amount of the subject light condensed by the photographing lens 1 moved in the optical axis direction by the focus ring 18 is controlled by an iris mechanism 2 for controlling the amount of the subject, and then the light receiving surface of the image sensor 3 is controlled. Imaged on top. The electrical signal photoelectrically converted by the element 3 is supplied to a photometric output circuit 20. In the output circuit 20, when the subject light is dark and falls below a predetermined level, the current control circuit 13 to be described later is activated and also supplied to the AGC circuit 4 for controlling the gain to a fixed amount. The output of the circuit 4 passes through a matrix circuit 5 and an encoder 6 for converting to an NTSC signal such as a television or a VTR, and is output as an output signal of a camera to an external device (not shown). The output of the AGC circuit 4 is controlled by a write-on signal from the CPU 9 or an external switch (not shown).
It is also supplied to the detection circuit 7 and the iris detection circuit 8.

When the light-on signal becomes active, the light power supply 14 starts to supply power to the movie light 12 as lighting means via the current control circuit 13. The output of the current control circuit 13 is input to one input terminal of an AWB circuit 19 that outputs white balance information to the matrix circuit 5 via the CPU 9. The other input terminal of the AWB circuit 19 has an AWB sensor
The sensor output of 21 is supplied via an amplifier 22.

In this case, conventionally, the irradiation light from the movie light 12 is received by the AWB sensor 21, and the color temperature information is subjected to arithmetic processing by a gain increase by the amplifier 22, and is transmitted to the matrix circuit 5 through the AWB circuit 19. The white balance was controlled by the application. On the other hand, in this embodiment, in addition to the white balance based on the sensor signal from the AWB sensor 21, the white balance based on the amount of electricity supplied to the movie light is performed. That is, the amount of electricity such as power, voltage and current supplied to the movie light 12 is detected by the current control circuit 13 and applied to the CPU 9. Then
The CPU 9 converts the quantity of electricity into a voltage value and a current value of a white balance system, and outputs the value to the matrix circuit 5 via the AWB circuit 19.
To perform white balance control in real time. As a result, it is possible to give an optimal white balance to a main subject to be shot by irradiating from a movie light, and, at the same time, to a subject in a distant view.
Appropriate white balance can be achieved.

Note that the white balance based on the sensor output from the AWB sensor 21 is omitted, and only the white balance based on the amount of electricity supplied to the movie light is used. Can be given. However, the white balance of a distant subject must be incomplete.

In the above embodiment, the power supplied to the movie light 12
The white balance was controlled based on the amount of electricity such as current and voltage. However, since the movie light originally emits tungsten light, its temperature changes due to light emission. Therefore, the white balance should be controlled based on this temperature change. Can also.

In this embodiment, the white balance operation control is fed back in real time. However, the white balance operation control is started after an appropriate dead time elapses, or the response speed is reduced. By performing processing such as delaying, it is possible to further reduce discomfort with respect to a change in color temperature in an actual shooting state.

Further, before manufacturing the camera, data in which the color temperature of the light emitted from the movie light 12 is plotted corresponding to the amount of electricity supplied to the movie light is obtained in advance, and this is stored in the CPU 9 in a conversion table. By inputting the amount of electricity detected by the current control circuit 13 to the CPU 9, the color temperature is output from the CPU 9 to the AWB circuit 19, thereby enabling quick auto white balance control. .

In the above-described embodiment, a camera of a type in which lighting means such as the movie light 12 is incorporated in the camera body has been described. However, a camera in which the lighting means is not incorporated in the camera body but is provided separately. It is needless to say that the present invention can also be applied to the present invention.

In the above embodiment, the description has been made with an example of a camera-integrated VTR. However, the present invention is not limited to this, and can be generally applied to cameras such as studio TV cameras, home video cameras, and electronic cameras. It is something.

For example, a low-cost camcorder has a preset mode corresponding to a light bulb, a fluorescent light, sunlight, and the like. Therefore, even in such a white balance control of the camcorder, the white mode based on the amount of electricity of the movie light is used. Control of balance can be used together.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an optimal white balance to a main subject to be illuminated and illuminated from the illumination means, and to prevent irradiation light from the illumination means from reaching. A remarkable effect that an appropriate white balance can be performed even on a subject in a distant view is exhibited.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a camera-integrated VTR showing one embodiment of the present invention, FIG. 2 is a diagram showing a color temperature of irradiation light corresponding to an amount of electricity supplied to a movie light, FIG. Is a general explanatory diagram of a color temperature, and FIG. 4 is a diagram showing an imaging field of view of a camera. 9 CPU (means for performing white balance control based on electric quantity) 13 ... current control circuit (means for performing white balance control based on electric quantity) 19 AWB circuit (means for performing white balance control based on electric quantity) 12) Movie light (lighting means)

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 9/04-9/11 H04N 9/64-9/78 H04N 5/222-5/257

Claims (1)

(57) [Claims] An illumination unit capable of continuously irradiating a subject with light, a power supply unit for supplying power to the illumination unit, and an electric amount for detecting an amount of electricity supplied to the illumination unit by the power supply unit. Detecting means, automatic white balance detecting means for detecting the color temperature information of the subject, and white balance based on the output from the automatic white balance detecting means and the electric quantity detected by the electric quantity detecting means. A camera comprising: white balance control means for controlling the camera.