JP3143112B2 - camera - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a camera, and more particularly, to a camera having illumination means for illuminating a subject.

[Prior Art] The operation of an iris and an AGC in a camera such as a TV camera for a studio, a home video camera, an electronic camera or a camera-integrated VTR will be described with reference to FIGS. 3 (A) and 3 (B).

FIGS. 3A and 3B are diagrams in which the horizontal axis represents the subject illuminance I and the vertical axis represents the video output level V of the camera. First, if the iris nor even operate AGC, as shown by the straight line l ₁ of the right upstream of FIG. 3 (A), in proportion to the increase of the subject illumination I output level V of the camera is increased. Therefore, the iris and the AGC are operated to level the video output. That the subject illumination output level V of the camera becomes the standard output Vs and I _1, it is set to F1.4 aperture open aperture value of this time. Then, the control of the diaphragm by the iris control circuit in the region where the object illuminance exceeds I _1, also a gain-up operation by the AGC circuit object illuminance is at I ₁ the following areas, performed respectively, resulting in a third view of (B) As indicated by the straight line l ₂ , the output level V can be made flat in a region where the illuminance of the subject is equal to or greater than I ₂ .

[Problems to be solved by the invention] However, in a conventional camera in which an iris and an AGC are operated to level a video output,
In the area of the iris control illuminance of the subject are above the I _1, S / N
Although concern that ratio is deteriorated is none, in the region of the gain-up operation by the AGC circuit Shitamawaru the I _1, for example, such as for the CCD of fixed noise constituting the imaging device is a gain-up, S / N ratio Will be degraded. That is, the third diagram obtained by plotting the S / N ratio with respect to the object illuminance in (C), the illuminance of the subject is Shitamawaru the I _1, as indicated by a straight line l ₄
S / N ratio is decreased, thereby reaching practically a minimum S / N ratio N ₁ at the object illuminance I _2.

Further, when the subject is located at a distant place, the auxiliary light may not reach the subject even when the illumination unit irradiates the subject with the auxiliary light.

In view of the above, an object of the present invention is to solve the above-described problem, and in a camera to which lighting means such as a movie light can be attached, even if the camera enters the gain-up operation area by the AGC circuit,
Provided is a camera capable of measuring a distance without deteriorating the / N ratio, and capable of controlling power supply to the illuminating means even when shooting a long-distance subject in accordance with the light emission amount characteristic of the mounted illuminating means. To be.

[Means and Actions for Solving the Problems] The first camera according to the present invention obtains information on the amount of light emitted from the detachable lighting means, and from the obtained information, the light of the lighting means can reach. A means for determining a distance; a recognition means for recognizing information relating to a gain operation of an AGC circuit for adjusting an output signal of the imaging means and an aperture operation of an iris control circuit for controlling the amount of light incident on the imaging means. Power supply control means for controlling power supply to the lighting means based on the determination by the determination means and the recognition result by the recognition means.

Further, the second camera according to the present invention obtains information on the amount of light emitted from the detachable lighting unit, and determines a reachable distance of the light from the lighting unit based on the obtained information. Distance detecting means for detecting information relating to the distance; and power supply controlling means for controlling power supply to the lighting means based on the determination by the determining means and the detection result of the distance detecting means. It is characterized by.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The present invention relates to a TV camera for a studio, a home video camera,
Although the present invention is widely applicable to electronic cameras and the like, this embodiment will be described below by taking the camera-integrated VTR shown in FIG. 1 as an example.

A focus motor 11 controlled by the autofocus device 10 rotates a focus ring 18 by a coupling mechanism (not shown), whereby the photographing lens 1 moves in the optical axis direction. Then, the subject light condensed by the photographing lens 1 is formed on the light receiving surface of the image sensor 3 after the light amount is controlled by the iris mechanism 2 which is driven by the iris control circuit 17 and controls the aperture of the subject light amount. You. The electric signal photoelectrically converted by the element 3 is an AGC circuit 4, a matrix circuit
5. The signal passes through the encoder 6 and is output to an external device (not shown) as an output signal of the camera. The output of the AGC circuit 4 is also supplied to an AGC detection circuit 7 and an iris detection circuit 8 controlled by a write-on signal from a CPU or an external switch (not shown).

The outputs of the AGC detection circuit 7 and the iris detection circuit 8 are C
It is also supplied to PU9. The CPU 9 is supplied with information on the distance to the subject from the autofocus device 10, and controls the power supplied to the illumination means.

In this case, the FIG. 3 (B), enters the area to decrease the illuminance of the subject from the point of view of the object illuminance I ₁ is a S / N degradation points P ₁ to (C), the prior art AGC circuit 4 and the AGC detector Circuit 7
The video output V is leveled by increasing the gain by a closed loop with the above. However, in the present embodiment, instead of this, when the video signal enters the area below the S / N deterioration point, FIG. As shown in the figure, the amount of light emitted from the illumination means such as the movie light 12 is changed in accordance with the illuminance of the object, thereby leveling the video output. That is, CP
When U9 recognizes the operation points of the AGC detection circuit 7 and the iris detection circuit 8, the U9 controls the amount of light emitted from the movie light 12 as a lighting means by the current control circuit.
Adjust with 13. Then, the control circuit 13 limits the current value supplied from the light power supply 14 to the movie light 12. This current control is adapted to emit light at the last minute light emission amount V _M ranges constant standard output Vs is obtained.

In the case of a distant subject, the distance information obtained by the autofocus device 10 (see FIG. 1) is supplied to the CPU 9, so that the CPU 9 uses this distance information as illumination means. It is determined whether or not the irradiation light of the movie light 12 can reach the subject. If it is determined that the irradiation light cannot be reached, the current control circuit 13 is instructed to stop the emission of the movie light 12.

Next, the operation of the present embodiment configured as described above will be described below. The CPU 9 detects the output level of the AGC circuit 4
The luminance information of the subject light transmitted through the photographing lens 1 via the light sources 7 and 8 is fetched. Then, the camera output is as shown in FIG.
In the case of exceeding the standard output Vs shown in ( ₁₎ , that is, in the iris control region where the illuminance is higher than the S / N deterioration point P1, the iris 2 is narrowed down by the detection output of the iris detection circuit 8 via the iris control circuit 17, and the imaging is performed A certain amount of subject light enters the element 3. On the other hand, if the camera output is less than the standard output Vs, i.e. the movie write control region of low illuminance than S / N degradation point P ₁ is, CPU 9 is
Reads it from the output of the AGC detector circuit 7, V _M of the difference between the video output represented by a straight line l ₁ of the standard output Vs and the second view (A)
Movie light emission corresponding to.

According to the above embodiment, as shown in FIG.
The S / N degradation points P ₁ iris control area of more than object illuminance I ₁ corresponding to, there is no room for causing degradation from the irradiation light amount is a constant S / N ratio of the image sensor 3 by the aperture control. On the other hand, in the movie light control area subject illuminance Shitamawaru the I _1, instead of the gain-up by the AGC control circuit which has been conventionally performed, and the standard output Vs, straight of FIG. 2 (A)
l there is no fear of causing deterioration of the S / N ratio because doing movie light emission corresponding to the V _M of the difference between the video output indicated by _1. Therefore, the S / N ratio of the camera video output is
As shown in FIG. 3B, a constant S / N ratio can be obtained over the entire iris control region and the movie light control region, and the effect of improving the S / N ratio indicated by oblique lines is expected. Can be.

In other words, the movie light control region Shitamawaru the S / N deterioration points P _1, conventionally, because it was carried out the gain-up operation by the AGC control circuit degradation of S / N ratio was inevitable, this embodiment without the S / N ratio is deteriorated in so was performed by turning on the movie lights, moreover V _M of the difference between the video output indicated the emission in a straight line l ₁ of the standard output Vs and the second view (a) Therefore, the consumption of the built-in battery can be reduced.

In the above embodiment, the amount of light emitted from the movie light is controlled using the detection information from both the AGC circuit and the iris control circuit for adjusting the output signal level of the image sensor. The improvement of the S / N ratio can be expected even if only one of them is used, not necessarily. That is, according to the iris opening information or the AGC on information, the information shown in FIGS.
Since the information that whether Shitamawa' the S / N deterioration point P ₁ is obtained, thereby improving the S / N ratio.
In this case, the signal to be taken into the CPU 9 is AGC in this embodiment.
The output signals of the detection circuit 7 and the iris detection circuit 8 are used. However, the present invention is not limited to this. The output signals of the AGC circuit 4 and the output terminal of the iris control circuit 17 may be used.

Further, in the above-described embodiment, a camera of a type in which lighting means such as a movie light is incorporated in the camera body has been described. However, a camera in which the lighting means is provided separately without being incorporated in the camera body, such as the first camera, Contact points are provided at points P ₂ and P ₃ in the figure, and a large amount or small amount of illumination means different from the camera body, for example, is externally attached to the contact parts. The present embodiment can of course be applied to a case where the power supply system to the lighting means is a separate system and the current control circuit in this system is controlled by the CPU 9. In this case, the reachable distance of light is different depending on the amount of light of the illuminating means provided separately from the camera body. Therefore, by capturing this kind of information into the CPU, the reachable distance of the light can be determined separately for each illuminating means. it can.

As described above, according to this embodiment, each circuit except for the CPU 9 has a configuration that is generally applied to a camera, and the cost of the CPU is decreasing, so that the effect is great.

[Effects of the Invention] As described above, according to the present invention, the power supply to the lighting means is controlled via the CPU by the output of the AGC detection circuit or the iris detection circuit, that is, the iris control exceeding the S / N deterioration point. In the region, the video output can be leveled without deteriorating the S / N ratio by iris control, and in the movie light control region below the S / N deterioration point, by turning on the illuminating means. Further, when photographing a long-distance subject, even when using a lighting unit attached to the camera, the reaching distance based on the light amount of the lighting unit is determined. Numerous remarkable effects such as stopping power supply to the lighting means are exhibited.

[Brief description of the drawings]

FIG. 1 is a block diagram of a camera showing an embodiment of the present invention, FIG. 2 (A) is a diagram of a video output obtained by the configuration in FIG. 1, and FIG. 3A to 3C are diagrams illustrating the control of an iris and an AGC normally used for a camera. 3. Image pickup device (imaging means) 4. AGC circuit 12 ... Movie light (lighting means)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/222-5/257 G03B 15/03 H04N 5/238

Claims (2)

(57) [Claims] 1. An information relating to an amount of light emitted from a detachable illuminating means, a means for judging a reachable distance of light of the illuminating means from the obtained information, and an output signal of an imaging means are adjusted. Recognition means for recognizing information related to the gain operation of the AGC circuit and the aperture operation of the iris control circuit for controlling the amount of light incident on the image pickup means; and the determination by the determination means and the recognition result by the recognition means. A power supply control unit configured to control power supply to the lighting unit based on the power supply. Means for obtaining information relating to the amount of light emitted from the detachable illumination means, judging the reachable distance of the light from the illumination means from the obtained information; and detecting information relating to the distance to the subject. A camera comprising: a distance detection unit that performs power supply; and a power supply control unit configured to control power supply to the illumination unit based on a determination made by the determination unit and a detection result of the distance detection unit.