JPH04156071A - Still video camera - Google Patents

Abstract

PURPOSE:To correct a recording signal against deficient illuminance at pickup by an auxiliary light and to prevent mistake in the pickup by detecting a level of a reflected light from an object and controlling the level of a recording signal from an image pickup element based on the detection level. CONSTITUTION:Exposure is implemented by the illuminance of an auxiliary light source 7, a dimmer sensor 8 receives a reflected light from an object and sends a data of a light receiving element level to a system controller 6. The system controller 6 takes an integration value P of the data, and the value P and a proper exposure Q are compared, and when the discrimination of the exposure indicates low-exposure, the system controller 6 controls a gain control circuit 4, it is operated to increase the amplification factor of an output stage amplifier 3 and a level of a signal inputted from a solid-state image pickup element 2 is amplified till the level is equal to a level at a proper exposure. Thus, the recording signal against deficient illuminance at pickup with an auxiliary light is corrected and mis-pickup is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a still video camera that records still images by electrical means.

[Conventional technology]

A conventional still video camera of this type is disclosed in, for example, Japanese Utility Model Application No. 60-50569.

When performing auxiliary light photography (stroboscopic photography), this still video camera uses a sensor to detect the distance to the subject before shooting, and based on the detection results, for example, even if the aperture is opened, the auxiliary light source (strobe) will not illuminate the subject. If it is determined that the output stage is insufficient, the gain of the amplifier in the output stage is corrected to be high and the image is taken. By correcting the recording signal in this manner, it is possible to prevent photographing errors during auxiliary light photographing.

[Problem to be solved by the invention]

However, in the conventional still video camera as mentioned above, the distance to the subject is detected in advance before shooting.
Since the gain of the amplifier in the output stage is controlled based on the detection distance, fixed-focus cameras become larger and more expensive due to the addition of a distance measurement mechanism, and the time required to detect the distance increases during shooting. There was a problem that the release time lag became long.

The present invention has been made with attention to these problems, and not only can the recording signal be corrected for insufficient illumination during auxiliary light photography, but it can also be constructed compactly and inexpensively, and can also eliminate the issue of long release time lag. It is not intended to provide a still video camera.

[Means to solve the problem]

The still video camera of the present invention includes a light source that illuminates a subject, a reflected light detection means that detects the level of light reflected from the subject by the light source, and controls the level of a recording signal from an image sensor based on the detected level. It is equipped with control means to

[Effect]

In the still video camera of the present invention, the level of reflected light from a subject irradiated by a light source is detected, and the level of a recording signal from an image sensor is controlled based on the detected level.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a still video camera according to an embodiment of the present invention. In the figure, 1 is a photographing lens that forms an image of imaging light from a subject on the imaging surface (light receiving surface) of a solid-state imaging device 2 such as a CCD, and the solid-state imaging device 2 converts the incident imaging light into an electrical signal (photoelectric conversion). ) and output. 3 is an output stage amplifier that amplifies the imaging signal from the solid-state imaging device 2; 4 is a gain control circuit that changes the gain of the output stage amplifier 3, and is provided as a control means for controlling the level of the imaging signal (recording signal). ing.

5 is a 330 circuit that outputs timing pulses for driving the solid-state image sensor 2; 6 is a system controller (hereinafter referred to as system controller) that controls the entire system; the gain control circuit 4 and 330 circuit 5 are controlled by this system controller 6; be done. Reference numeral 7 denotes an auxiliary light source for illuminating the subject, and 8 denotes a dimming sensor for controlling the amount of light from the auxiliary light source 7, which constitutes reflected light detection means for detecting the level of light reflected from the subject by the auxiliary light source 7. . 9 is a signal processing circuit that processes the signal from the output stage amplifier 9 and converts it into a video signal that can be recorded on a recording medium; 10 is a recording circuit that records the video signal on the recording medium; and 11 is a release switch.

Next, the operation will be explained.

When the release switch 11 is turned ON during auxiliary light photography, the 330 circuit 5 is controlled by the system controller 6, and the 330 circuit 5 outputs a timing pulse for charge accumulation to the solid-state image sensor 2, and the auxiliary light source Exposure is performed by the light emitted at step 7. At this time, the light control sensor 8 is
It receives the reflected light from the subject and sends data on the level of the received light to the system controller 6. Inside the system controller 6, the integral value P of this data is taken, and this value P is compared with the appropriate exposure value Q. If the difference between these values is P-Q<O, it is determined that the exposure is underexposed, and P-Q> If O, it is overexposed, and P-Q=O
If so, it is determined to be appropriate.

After the exposure is completed, the system controller 6 controls the 330 circuit 5 to give a timing pulse to the solid-state image sensor 2, and the solid-state image sensor 2 reads out the accumulated charge based on this timing pulse. The signal output from the solid-state image sensor 2 by this readout operation is input to the output stage amplifier 3, where it is amplified to a level necessary for changing into a signal for recording as described above. At that time, if the exposure state is determined to be underexposed, the gain control circuit 4 is activated under the control of the system controller 6 to increase the amplification factor of the output stage amplifier 3, and the level of the signal input from the solid-state image sensor 2 is It is amplified until it reaches the same level as when properly exposed. Then, a video signal at the same level as the proper exposure is always inputted to the signal processing circuit 9 through a path from the solid-state image sensor 2 to the output stage amplifier 3, where it is converted into a signal for recording, and then recorded. circuit 1
0 is recorded on the recording medium.

In this way, the recording signal can be corrected for insufficient illumination during auxiliary light photography, and photography errors can be prevented. Here, since a distance measuring mechanism is not provided in this embodiment, it can be constructed in a small size and at low cost. Furthermore, since the recording signal is corrected after exposure is completed, the release time lag does not become long.

FIG. 2 is a block diagram showing another embodiment of the present invention,
The same reference numerals as in FIG. 1 indicate the same components. This embodiment is provided with a solid-state image sensor 12 capable of storing frames and a signal level detection circuit 13 that detects the level of the output signal of the solid-state image sensor 12.

The operation of the normal field shooting mode in a still video camera with such a configuration is the same as that of the camera shown in FIG. As in the embodiment, the exposure level is determined by the light control sensor 8. When this exposure level determination is, for example, under, the gain control circuit 4 immediately
Instead of increasing the gain of the output stage amplifier 3 by controlling the SSG circuit 6, the system controller 5 first controls the SSG circuit 6 to change the readout drive timing pulse of the solid-state image sensor 12 from that for a frame to that for a field. As a result, the output of the signal from the solid-state image sensor 12 is approximately doubled, and the level of this doubled signal is detected by the signal level detection circuit 13 and the level value is transmitted to the system controller 6. The system controller 6 determines whether the signal level is overexposed, underexposed, or appropriate, and if it is overexposed, controls the gain control circuit 4 described above to lower the gain of the output stage amplifier 3.
If it is under, the gain will be increased, and if it is appropriate, the gain will remain at the normal setting value. These solid-state image sensors 1
2, the signal level detection circuit 13 and the output stage amplifier 3, a video signal of the same level as the proper exposure is always input to the signal processing circuit 9, where it is converted into a recording signal and then recorded. Recorded in circuit 10.

In this embodiment as well, as in the above-described embodiments, it is possible to correct for insufficient illumination during auxiliary light photography without using a distance measuring mechanism, and it is possible to eliminate photography errors. Also, the release time lag does not become long.

In each of the above embodiments, the gain of the output stage amplifier of the image sensor is controlled, but the output level of the image sensor may be directly controlled.

〔Effect of the invention〕

As described above, according to the present invention, the level of reflected light from the subject is detected and the level of the recording signal from the image sensor is controlled based on the detected level, so that insufficient illumination during auxiliary light photography can be avoided. It is possible to correct the recording signal for the camera, prevent photographing errors, be compact and inexpensive, and have the advantage of not increasing the release time lag.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a still video camera according to one embodiment of the invention, and FIG. 2 is a block diagram showing another embodiment of the invention. 2.12 --- Solid-state image sensor 3 --- Output stage amplifier 4 --- Gain control circuit (control means) 6 --- System controller 7 --- Auxiliary light source 8 --- II optical sensor (Reflected light detection means) 10---
--Recording circuit

Claims (1)

[Claims] A light source for illuminating a subject, a reflected light detection means for detecting the level of light reflected from the subject by the light source, and a control means for controlling the level of a recording signal from an image sensor based on the detection level. A distinctive still video camera.