JPH01298878A - Automatic diaphragm - Google Patents

Abstract

PURPOSE:To adjust the diaphragm automatically so as to always obtain a pick up signal of a proper level even if the pick up condition is subject to change by switching the photometric range in response to the pick up condition. CONSTITUTION:The 1st photometric range setting circuit 9 sets a photometric range 31 to a part nearly below the middle part of a pick up pattern 20 suitable for outdoor pick up where a light background such as the sky frequently comes around the center of pattern and outputs a photometric range indication signal S1 at an H level in the photometric range 31 and at an L level at other than the said range. Moreover, the 2nd photometric range setting circuit 10 eliminates an upper part of the pick up pattern 20 from a photometric range 32 so as to be suitable for the case of indoor pick up where a bright light source such as a fluorescent light exists only at the upper part of the pick up pattern 20 and outputs a photometric range indication signal S2 at an H level in the photometric range 32 and at an L level at other than the said range. Then a switch 11 is changed over depending whether the pick up condition is outdoor or indoor. Thus, a pick up signal with a proper level is always obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic aperture device used in an imaging device such as a video camera.

[Prior Art] Fig. 5 is a block circuit diagram showing an example of a conventional automatic aperture device. In Fig. 0, (1) is a lens, (2) is an aperture, (3) is an imaging unit, and (7) is the photometry range setting circuit, (4)
is a photometry circuit that passes an imaging signal within the photometry range set by the photometry range setting circuit (7). (5) is a detection circuit,
A photometric signal of a level corresponding to the average usage of the input imaging signal is output. (6) is an aperture control circuit that controls the aperture (2) so that the level of the photometric signal becomes a predetermined level.
Adjust. (8) is a video signal processing circuit.

Next, the operation will be explained. The image light that enters through the lens (1) passes through the aperture (2) and forms an image on the imaging surface of the imaging unit (3), and an imaging signal with a level corresponding to the brightness of the incident image light is generated. Output. On the other hand, the photometry range setting circuit (7) outputs a signal So indicating a predetermined photometry range (30) on the imaging screen (20), as shown in FIG. As shown in FIG. 6, this photometry range instruction signal SO is "H+t level" within the photometry range (30), and "H+t level" in other ranges.
This is a signal that becomes L'° level, and in this example, the Il image screen (
20) One part of 4 has been removed. Photometric circuit (4)
allows the imaging signal input from the imaging section (3) to pass only when the photometry range instruction signal So is at the "H" level, and this imaging signal is integrated by the detection circuit (5) to determine the photometry range (30 ) is applied to the aperture control circuit (6), and the aperture (2) is adjusted so that the input photometric signal reaches a predetermined level. As a result, an image signal of an appropriate level is input to the video signal processing circuit (8). The reason why the upper part of the imaging screen (20) is not included in the photometry range (30) is that when taking pictures, bright backgrounds such as the sky or electric lights generally appear in the upper part of the imaging screen (20). In this case, this part is included in the photometry range (30).

This is to avoid the situation where the diaphragm (2) is closed because a photometric signal at a level higher than the level corresponding to the actual brightness of the subject is detected, and the imaging signal becomes darker than the appropriate level.

[Problem to be solved by the invention] As the conventional automatic aperture device has a fixed metering range as described above, it is suitable for outdoor shooting where bright backgrounds such as the sky often come close to the center of the screen. If you set the metering range in such a way, the imaging signal of the subject will become darker when shooting indoors, where bright light sources such as fluorescent lights are often located only above the screen. If you set the metering range, there is a problem that the camera becomes too bright when shooting outdoors, and if you set the metering range between outdoors and indoors, you will not be able to obtain an appropriate level of imaging signal both outdoors and indoors. was there.

This invention was made to solve the above-mentioned problems, and it is possible to adjust the aperture so that an image signal of an appropriate level can always be obtained even when the shooting conditions change, such as when shooting outdoors or indoors. The purpose is to obtain an automatic squeezing device that can

[Means for Solving the Problems] The automatic diaphragm device according to the present invention has means for switching the photometry range set on the imaging screen so as to obtain imaging signals of respective appropriate levels according to various imaging conditions. It is characterized by the following.

[Function] The photometric range switching means of the present invention switches the photometric range according to the shooting conditions, so that even if the shooting conditions change, the aperture is automatically adjusted so that an image signal at an appropriate level is always obtained. .

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
In the figure, the same reference numerals as in FIG. 5 indicate the same parts, so the explanation will be omitted.

(9) is a first photometric range setting circuit that outputs a photometric range instruction signal sl for outdoor photography; (10) is a second photometric range setting circuit that outputs a photometric range instruction signal S2 for indoor photography; (11) ) is the first depending on whether you are shooting outdoors or indoors. This is a switch that switches the output signals of the second photometric range setting circuits (9) and (10) and inputs them to the photometric circuit (4).

Next, the parts of the operation of this embodiment that are different from the conventional example shown in FIG. 6 will be explained.

The first photometry range setting circuit (9) is configured to set the imaging screen (2) as shown in FIG.
The area below the center of 0) is defined as the 'side light range (31), and the photometry range instruction signal S1 is output at "H" level within the photometry range (31) and at "L11 level" for the rest of the range. In addition, the second photometry range setting circuit (10) is configured as shown in FIG.
As shown in b), the upper part of the imaging screen (20) is removed from the photometry range (32), and the area within the photometry range (32) is “H”.
"level", and "L" level for other ranges.Then, the switch (11) is changed depending on whether the shooting conditions are outdoors or indoors, and if the shooting conditions are outdoors, the first photometry range is output. The output signal Sl of the setting circuit (9) is used as the output signal Sl of the second photometry range setting circuit (10) when indoors.
2 is given to the photometric circuit (4). The photometry circuit (4) passes the imaging signal according to the input photometry range instruction signal,
The detection circuit (5) integrates this imaging signal and outputs a photometric signal of a level corresponding to the average usage. Aperture control circuit (6
) adjusts the aperture (2) so that the input photometric signal reaches a predetermined level, and as a result, an image signal of an appropriate level is input to the video processing circuit (8).

In the above embodiment, the photometry range instruction signals Sl and S2 output from the first and second photometry range setting circuits (9) and (10) are adapted to suit outdoor photography and indoor photography, respectively. However, as shown in Fig. 3(a), it has a photometric range (33) only for the center, for photographing people.
It may also be used for landscape photography, having a photometry range (34) excluding the peripheral area of the imaging screen as shown in FIG. 3(b).
In this case, the outputs of the photometry range setting circuits (9) and (10) are horizontal photometry range instruction signals S3H, 54H,
This is the AND of the vertical direction photometry range instruction signals S3V and s4V.

Furthermore, in the above embodiment, the photometry range was switched depending on the subject to be photographed by switching between two photometry range setting circuits, but as shown in FIG. 4, it is possible to output three or more photometry range instruction signals Si. A variable photometry range setting circuit (12) is provided to set three or more photometry ranges according to the photometry range switching signal Si input from the input terminal (13), for example, as shown in FIG. 2(a).
, (b) and those shown in FIGS. 3(a) and (b).

[Effects of the Invention] As described above, according to the present invention, the photometry range is switched according to the shooting conditions, so that even if the shooting conditions change, an image signal of an appropriate level can always be obtained.
This has the effect of providing an automatic aperture device that can automatically adjust the aperture.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing the photometry range of this embodiment. FIG. 3 is a diagram showing the photometric range of another embodiment of the present invention, FIG. 4 is a block circuit diagram of another embodiment of the invention, FIG. 5 is a block circuit diagram of a conventional automatic aperture device, and FIG. The figure shows the photometric range. (1)...Lens, (2)...Aperture, (3)...
Imaging unit, (4)...photometering circuit, (5)...detection circuit, (8)...aperture control circuit, (9), (10)
...photometering range setting circuit, (11)...switch,
(12)...Variable photometry range setting circuit, (20)...
・Image screen, (31), (32), (33)
, (34)...Photometry range. In each figure, the same reference numerals indicate the same, corresponding parts.

Claims (1)

[Claims] (1) Photometry in which the aperture of the lens that forms the optical image of the subject on the imaging surface of the imaging unit is set on the imaging screen that is displayed by the imaging signal output from the imaging unit. In an automatic aperture device configured to extract a portion corresponding to a range, detect a photometric signal at a level corresponding to the brightness of the area, and adjust the aperture so that the photometric signal reaches a predetermined level, An automatic aperture device characterized by comprising means for switching the photometric range to a predetermined photometric range for each of a plurality of different photographing conditions.