JPS63123278A - Image pickup device - Google Patents

Abstract

PURPOSE:To attain exposing control with high accuracy by obtaining an optimum exposing quantity with high accuracy by an automatic diaphragming to weighted to a screen and executing a direct photometry based on it. CONSTITUTION:A photometric pattern selected from a pattern presetting device 83 is inputted to a control circuit 8. The light from object passes through a lens 2, a diaphragm 3, a half mirror 4 and a shutter 8, and is made incident on a sensor 6. The image pickup output from a sensor 6 is transferred to a recording part 62 as a video signal inputted from an incident light to a camera circuit 61. The video signal displayed at a terminal 610 is inputted to a gate 7. A gate signal from a gate pattern generating device 71 is inputted to the gate 7, and the video signal weighted by the light measuring pattern due to the pulse is inputted to an automatic diaphragming circuit 33. At such a time, the output of a photometric circuit 41, in which the light from an object 1 is made incident from a half mirror 4, shows a suitable exposing quantity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has an image sensor such as a solid-state image sensor and an image recording means, and is equipped with a shutter means for accumulating and reading signal charges of the image sensor. The present invention relates to an imaging device.

[Conventional technology]

A so-called electronic camera has been developed as an imaging device that records an image signal using an imaging sensor and an image recording means.

Conventional imaging devices of this type are known, for example, from [Technical Report of the Television Society of Japan by Bengami et al., TEBSloo-4, Vol.
As disclosed in "Electronic Still Camera" on pages 7 to 22, the exposure is controlled by direct photometry to obtain the necessary exposure accuracy and take pictures.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, the photometry is center-weighted photometry, so when various subjects are photographed, overexposure or underexposure may occur depending on the background of the subject, etc. In other words, high exposure accuracy can be obtained for subjects with hazy brightness, but for other subjects, no consideration has been taken to adjust the exposure amount depending on the brightness distribution of the subject, and the exposure may vary depending on the subject. There was a problem that the exposure error became large.

SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging device that can control exposure amount with high precision regardless of the brightness distribution of a subject.

[Means for solving problems]

The above objectives are to create a diaphragm control signal from an arbitrarily weighted video signal on the screen and perform highly accurate closed-loop automatic diaphragm control to perform optimal diaphragm control; This is achieved by employing a means for photometering the light incident on the sensor and an exposure control means for performing direct photometry control using the photometer.

[Effect]

The aperture control means, which performs control with arbitrary weighting on the screen, is a closed-loop control and can perform exposure control with high precision. Therefore, the amount of exposure to the image sensor for each screen obtained from the photometry means is This is the exact value after exposure correction. Therefore, if the exposure control means performs shutter shooting control using direct metering to obtain the same exposure amount as this exposure amount, since direct metering itself has high exposure accuracy, exposure control with highly accurate exposure compensation can be performed. possible and will not malfunction.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an imaging device according to the present invention, in which 1 is a subject, 2 is a lens, 3 is an aperture, and 4 is a block diagram showing an embodiment of an imaging device according to the present invention.
is a half mirror, 15 is a shutter, 6 is a solid-state image sensor (hereinafter referred to as a sensor), 7 is a gate, 8 is a control circuit, 41 is a photometric circuit, 42 is a switch, 43 is a latch circuit, 44 is a comparison circuit, and 45 is a shutter a control circuit, 51 a switch;
52 is a shutter opening circuit, 61 is a camera circuit, 62 is a recording section, 63 is a sensor drive circuit, 71 is a gate slam generation circuit, 72 is a synchronization signal generation circuit (hereinafter referred to as SSG),
81 is a shirt button; 82 is a preset device for pre-inputting the aperture value in case of an aperture priority method; and 83 is a preset device for pre-inputting photometry formats such as bang metering and weighted metering by the user. ,
A and B are terminals to which signals A and B from the control circuit 8 are input.

This embodiment will be described assuming shutter photography using an aperture priority method.

Fig. 2 is a waveform diagram explaining the operation of Fig. 1, and Fig. 3 is a waveform diagram explaining the operation of Fig. 1.
It is a flowchart explaining the operation|movement of a figure.

The operation in this embodiment is divided into two parts, which will be explained in order.

The first operation is to control the aperture using automatic aperture control and find the appropriate exposure amount.The next step is to change the aperture to a preset value and control the shutter speed to obtain the same exposure as the appropriate exposure amount obtained in the first operation. This is a second operation in which an exposure operation is performed by direct photometry in which the shutter is kept open until the desired amount of light is obtained.

The operation shown in FIG. 1 will be explained below with reference to FIGS. 2 and 3.

First, by turning on a power switch (not shown), automatic aperture control is performed starting from "start" in FIG. 3 until the shirt button is pressed. Switches 42, 51 shown in FIG.
31 is placed in the illustrated position and the shutter 5 is in an open state.

The photometric button selected by the button presetting device 83 is input to the control circuit 8 . In the present invention, an example of automatically selecting a photometric button will be described later, so for the sake of simplicity, it will be assumed here that a photometric button with a larger weight in the center is selected. Examples of this baton generation will also be described later. According to the selected button, the control circuit 8 generates a gate button generating circuit 71.
This causes a gate slam.

Light from subject 1 is transmitted through lens 2, aperture 3, and half mirror 4.
, passes through the shutter 5 and enters the sensor 6. Based on the incident light, the imaging output from the sensor 6 is transmitted to the recording section 62 as a video signal that is input to the camera circuit 61 . terminal 6
The video signal appearing at 10 is input to gate 7.

A gate pulse generated from a gate slam generator 71 is input to the gate 7 , and a video signal (signal for automatic iris) weighted by the photometric button generated by this pulse is input to the automatic iris circuit 33 . Aperture 3 by automatic aperture circuit 33
is controlled, and the aperture is changed until the weighted video signal becomes equal to the value preset in the automatic aperture circuit 33. When this change is completed, the output of the photometry circuit 41 which receives the light from the subject 1 through the half mirror 4 indicates the appropriate exposure amount.

It is assumed that the photometry circuit 41 is configured with an integral meter and has a function of resetting the period of automatic aperture control for each field. The photometric output becomes a triangular wave with a peak value .

In the figure, (A) is a V pulse indicating a vertical synchronization signal. That is, the output V of the photometric circuit 41.

is the value representing proper exposure.

Next, a case where the shutter button 81 is pressed and shutter photography is performed will be described.

As shown in FIG. 2, the control circuit 8 that detects the start of shutter shooting when the shutter button 81 is pressed at the time indicated by ()) is connected to the photometry circuit 41 indicated by (O) at the beginning after the shutter is 0N ()). The value immediately before the reset is sampled and held by the latch circuit 43 (step S4 shown in FIG. 3).

Next, the aperture value is fetched from the preset device 82 (step S), and the switch 42.51 is
．． 31 to prepare for shutter photography (step 36)
. For shutter photography, the control circuit 8 first starts with the preset device 82.
The aperture 3 is narrowed down by the aperture preset circuit 32 to the input value from , and at the same time the shutter control circuit 45 closes the shutter 5, and the sensor drive circuit 62 stops reading the sensor (step St). Next, after the setting of the aperture 3 is completed, the photometry circuit 41 is reset by a pulse input from the terminal B, and the shutter control circuit is opened to start exposure. The change in the output of the photometric circuit 41 is shown in FIG. When the shutter control circuit 45 detects a change in the output and generates a signal, the shutter control circuit 45 immediately closes the shutter 5 and completes the exposure. This is shown in (J) in FIG. 2, and the shutter speed in this case is the time shown in (R) in FIG.

FIG. 2 shows an example in which the aperture 3 is opened further than the automatic aperture value and the shutter speed is shorter than one horizontal period. However, in this example, the sensor is assumed to output a field image, and it goes without saying that this is different in the case of a frame image output sensor.

The sensor drive circuit 63 starts reading the sensor 6 at the time indicated by (ri) when the exposure is completed at the time indicated by (nu) in FIG.
is restarted, and recording is performed by the recording unit 62. (Step S1
゜).

After that, the signal to terminal A turns the switch 31°42.5
1 to restart automatic aperture control (step S+
+).

By repeating this process, shutter photography can be performed repeatedly.

The above is the photographing operation of the first embodiment of the present invention shown in FIG.

FIG. 4 is an explanatory diagram showing an example of the gate button in FIG. 1. (a) is a gate button corresponding to center-weighted photometry as an example of the gate button, and (b) is a waveform diagram of the gate pulse in (a). be.

In the same figure, (wo) is the gate button (a) is the vertical synchronization pulse, (wa) is the gate pulse 1 waveform shown correspondingly, (
(Y) is the horizontal synchronizing pulse (H pulse), and (Y) is the corresponding gate pulse 1 waveform.

FIG. 5 is a block diagram (a) of gate pulse generation and a waveform diagram (b), in which 711 is a synchronization pulse input terminal indicated by (even), 712 is a sine wave generation circuit indicated by (shi), and 712 is a sine wave generation circuit indicated by (shi). oscillates in synchronization with A threshold circuit 714 clips a part of the sine wave indicated by ( ) as indicated by ( ). 716 is a non-linear circuit in which the threshold circuit output (S) is further flattened as shown by (T), and the weighting is adjusted.

FIG. 6 is a block diagram (a) showing an example of a gate circuit;
b) A specific circuit diagram of a linear gate circuit. This gate needs to be a so-called linear gate in order to weight the video signal as an aperture signal. Therefore, it is necessary to perform DC reproduction of the video signal and gate pulse702
is the clamp circuit for that purpose. Further, 705 is a linear gate, whose detailed circuit is shown in FIG. In the same figure (b), R+ + Rz + R3r
R4 is a resistor, E+, Et, and R3 is a voltage source, QI.

Qz, Qs, Qa, Qs, and Qb are transistors, and by configuring them as shown in the figure, a linear gate can be easily realized. However, DC of terminal 702゜701
Of course, the reproduction potential, resistance value, voltage, and transistor are determined depending on the actual usage conditions.

FIG. 7 is an explanatory diagram showing another example of the gate pattern,
Multiple patterns (su・), (u), (mu).

(1) This is a pattern in which weights are attached to (1) for photometry.

The gate pulse waveform, generation method, and gate according to the gate pattern shown in FIG. 7 are shown in FIG. 4 above.

Since there is essentially no difference from the cases shown in FIGS. 5 and 6, the explanation thereof will be omitted.

FIG. 8 is a block diagram showing a specific example of an exposure correction circuit using a gate pattern, in which 901 is a gate pattern generation circuit, 9021 to 9025 are gates, and 9031 to 9035 are low pass filters (LP
F), 904 to 908 are terminals, 909 is a correction calculation circuit, 9101 to 9105 are variable gain amplifiers, 911 is an adder, and 910 is an output terminal, which is connected to the automatic aperture circuit 33. Gate 9021 from gate bang generation circuit 901
~9025 is shown in Figure 7 (su), (u), (mu),
(tsu).

It is assumed that a gate pulse shown in (1) is supplied to allow the inside to pass. The outputs of the LPFs 9031 to 9035 correspond to the luminances in (su) to (1) of the gate pattern. The correction calculation circuit 909 detects the brightness of each output and changes the gains of the variable gain amplifiers 9101 to 9105 according to the following pattern.

■ If the brightness difference between (S) and (1) is within a certain value,
The gains of variable gain amplifiers 9101 to 91o5 are made the same.

■ If (S) or (U) is high brightness, lower the gain of the variable gain amplifier corresponding to the high brightness area and increase the gain of the other.

■ If only (Mu) has low brightness, increase the gain of the variable gain amplifier corresponding to (Mu) and lower the others.

The change value of this gain, the threshold for determining high brightness, etc. need to be determined by actual photography.

Such a correction calculation circuit includes LPF9031 to 9035.
It can be easily configured by A/D converting and importing the values of and creating a table corresponding to each A/D converted value.

The gist of the present invention is to determine the optimal exposure amount with high precision using an automatic diaphragm that weights the screen, and to perform direct photometry based on the determined exposure amount.

As a result, it goes without saying that this method can be used not only for shutter photography, but also for still image photography by continuous stopping for a long period of time, and for daylight synchronized photography with a strobe.

〔Effect of the invention〕

As explained above, according to the present invention, highly accurate exposure 111-1III can be performed with a simple configuration.
It is possible to provide an imaging device with excellent functions that is low cost, compact, and has improved usability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the imaging device according to the present invention, FIG. 2 is an operation waveform diagram of FIG. 1, FIG. 3 is a flowchart explaining the operation of FIG. 1, and FIG. FIG. 5 is an explanatory diagram showing an example of the gate pattern in the figure. FIG. 5 is a block diagram illustrating the gate pulse generation circuit. FIG.
The figures are (a) a block diagram explaining the gate circuit, (b) a specific circuit diagram of the linear gate circuit, Fig. 7 is an explanatory diagram showing another example of the gate pattern, and Fig. 8 is an exposure correction circuit using the gate pattern. It is a block diagram showing a specific example. l...Subject, 2...Lens degree, 3...Aperture, 4
... Half mirror 15 ... Shutter, 6 ... Image sensor, 61 ... Camera circuit, 62 ... Recording section, 4
DESCRIPTION OF SYMBOLS 1... Photometry circuit, 43... Latch circuit, 44... Comparison circuit, 45... Shutter control circuit, 61... Camera circuit, 62... Recording section, 63... Drive circuit, 7・
...Gate, 71...Gate bang generation circuit, 33.
... Automatic aperture circuit, 8... Control circuit, 81... Shirt button, 82... Preset device, 83... Pattern preset device. Figure 2 t) Mr. sl -1-11-L-11111-
-1-Figure 3Figure 4 (Il Vt1ics-1''--1111111---L-rσ)
(3) Ketono'Rusl -1--r'----
゛＼－－－－(bnogate pulse

Claims (1)

[Claims] 1. In an imaging device comprising at least an image sensor, a shutter, an aperture, a photometry section, and a recording section, the aperture is determined by an aperture signal obtained by arbitrarily weighting an image signal from the image sensor when the shutter is opened. a first control means for controlling the shutter, a second control means for controlling the shutter according to an output signal from the photometry section, and an output signal that is the same as the first photometry output signal obtained by the first control means. A third control means is provided for controlling the second control means such that the second control means is obtained from the photometry unit when the second control means operates, so that the exposure amount can be adjusted with high precision according to the luminance distribution of the subject. An imaging device characterized in that it is configured as follows.