JP2730909B2 - Imaging device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an imaging device.

[Prior Art] In a still video camera that projects an object on an image sensor via a lens, converts this into an electric signal, and magnetically records it on a magnetic sheet, photometry is performed using an optical sensor (such as a photodiode). I was doing.

[Problems to be solved by the invention]

However, in the above conventional example, in order to perform photometry, an optical sensor, a lens for an optical sensor, a correction circuit for correcting a variation in the optical sensor, and
An adjustment process and the like are required, which complicate the structure of the camera and increase the cost.

Further, when photometry is performed in a specific area, another photosensor is required or the photometry surface is complicated.

Therefore, an object of the present invention is to provide an imaging device which has solved the above-mentioned problems.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an image pickup unit that converts an optical image into an electric image signal and an accumulation time in the image pickup unit for each of a plurality of predetermined partial areas. Control means for controlling differently to simultaneously perform an accumulation operation, and accumulation of the partial area by selecting only a signal of a predetermined level from among the image signals from the plurality of partial areas obtained from the imaging means. Selecting means for selecting a time as an accumulation time of an appropriate exposure.

[Operation] According to the present invention, the accumulation time in the image pickup means is controlled so as to be different for each of the plurality of predetermined partial areas so that the accumulation operation is performed simultaneously, and By selecting only a signal of a predetermined level from among the image signals, the accumulation time of the partial area is selected as the accumulation time of the proper exposure. As a result, an image signal for proper exposure can be obtained in a short time.

〔Example〕

 FIG. 1 shows an SV camera according to an embodiment of the present invention.

In the figure, 100 is a lens, 101 is an aperture, 102 is a driver for driving the lens and the aperture, 103 is an image sensor, 104 is a process circuit that generates luminance and color difference signals from signals output from the image sensor 103, and 105 is a process circuit. A recording circuit that performs processing such as modulation on the luminance and color difference signals output from the circuit 104, 115 is a video floppy which is a magnetic recording medium, 116 is a motor for rotating the video floppy 115, and 113 is a recording on the video floppy 115. Recording head to do, 1
14 is a driver for driving the recording head 113 and the motor 116, 106 is an AE circuit for performing photometry from a signal output from the image sensor 103, 108 is a strobe, 109 is an LCD for displaying a state, 110 is I / O Circuits, 111 and 112 are switches, 107
Is a CPU that controls the whole.

The case where partial photometry is performed in the above configuration will be described with reference to the flowchart of FIG.

First, it is detected that the switch 111 (SW1) is pressed (S2
00), partial light metering is performed on the designated area with the aperture opened by this switch input (S201). Next, the switch input is detected (S202), and when the switch 111 (SW1) is pressed again, the process returns to S201 to repeat the partial photometry.
Also, if the switch 112 (SW2) is pressed, it is judged comprehensively from the measured values of the partial photometry performed so far, and the optimum aperture value and shutter speed are determined (S203). Photographing is performed (S204).

Here, there are various ways of designating the area for performing the partial photometry, and this is not limited.

Next, the partial photometry in S201 will be described with reference to the flowchart in FIG.

The imaging device 103 can output one arbitrarily designated line, and can clear one arbitrarily designated line (no charge). Therefore, first, all lines are cleared (S300). Next, in order to perform partial photometry, as shown in FIG. 4, 2 ⁿ⁻¹ · t (n = 1) for each of m lines in the designated area (m varies depending on the width of the designated area). , 2, 3,..., T are exposed for the shortest time of the electronic shutter, and the AE circuit 106 detects n which is the optimal exposure. N at this time is N =
Assuming that n, 2 ^N-1 · t corresponds to the shutter speed,
Also, since the aperture value (open) at this time is known, an approximate EV value can be obtained from the optimum EV values at m places (S30).
1).

Next, clear is performed again for all rows of the image sensor (S302). Assuming that the allowable error of the EV value is ± Δε and the corresponding exposure time is τ, 2 ^N−1 · t is centered within the range of ± 1 of the EV value obtained above at m locations as described above. In addition, the exposure time of each line is changed by an integral multiple of ± τ, and the optimal EV of the designated area is determined based on the exposure time of the line that provides the optimum exposure and the aperture value (open) at this time.
The value can be obtained (S303).

[Other embodiments]

FIGS. 3-b and 3-c are flowcharts of the second and third embodiments of the partial photometry in FIG. 2 S201, and are otherwise the same as those of the first embodiment.

 In the drawings, common components are denoted by the same reference numerals.

In FIG. 3-b, the image sensor is cleared (S300),
An approximate EV value is measured (S302). Next, the aperture 101 corresponding to the obtained EV value is set (S304), and clearing is performed again for all rows of the image sensor (S302). Then, the optimum EV value of the designated area is obtained (S303). However, the aperture value for obtaining the EV value is the value in S304.

In FIG. 3-c, the image sensor is cleared (S30
0), an approximate EV value is measured (S302). Here, if the minimum time of the electronic shutter is relatively long,
If the value is large, the image sensor will be overexposed,
Measurement becomes impossible (S305). In such a case, the stop 101 that can be measured is measured (S304), and again,
Repeat photometry. However, the aperture value for finding the EV value is S3
It becomes the value in 04.

〔The invention's effect〕

As described above, according to the present invention, a proper exposure portion can be extracted by one imaging operation.
An image signal of proper exposure can be obtained in a short time.

[Brief description of the drawings]

 Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a flowchart of the embodiment, Fig. 3 is a flowchart of S201 in Fig. 2, and Fig. 4 is an explanatory diagram of partial photometry.

Continued on the front page (72) Inventor Nobuo Fukushima 770 Shimonoge, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Inside the Tamagawa Works (72) Inventor Yuji Eiki 770 Shimonoge, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Tamagawa Works ( 56) References JP-A-63-59070 (JP, A)

Claims (1)

(57) [Claims] 1. An image pickup means for converting an optical image into an electric image signal, and a control means for controlling an accumulation time in the image pickup means to be different for each of a plurality of predetermined partial areas so as to simultaneously perform an accumulation operation. Selecting means for selecting an accumulation time of the partial area as an accumulation time of a proper exposure by selecting only a signal of a predetermined level from among image signals from the plurality of partial areas obtained from the imaging means; Imaging device having the same.