JPH07105911B2 - Electronic camera device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic camera device, and is particularly suitable for use in a device having both functions of a still camera (for still images) and a video camera (for moving images). is there.

[Conventional technology]

There is known an electronic still camera in which a solid-state image sensor such as a CCD and a magnetic disk drive are compactly integrated. If the output of the image sensor of this still camera is taken out and led to the VTR, it can be used as a normal video camera. However, in order to use both of them, a shutter mechanism as a still camera and an auto iris mechanism as a video camera are required respectively.

The shutter mechanism is of the spring-charged type used in silver halide film photo cameras and does not have a diaphragm function. On the other hand, the auto iris mechanism controls the aperture opening with an iris motor, and cannot expect high-speed operation like a shutter.

Therefore, both mechanisms must be provided individually, resulting in a large mechanism size and high cost.

[Problems to be solved by the invention]

Japanese Unexamined Patent Publication No. 59-64974 discloses an image pickup device for both still images and moving images, which can be operated as a shutter by opening and closing the diaphragm blades of the iris mechanism during still image shooting. Since it is opened and closed mechanically, there is a problem that the exposure time control accuracy is low and a high-speed shutter operation cannot be obtained. In Japanese Patent Laid-Open No. 58-117776, the exposure time is controlled by a combination of the charge accumulation timing and the shutter closing timing to perform highly accurate exposure time control to obtain a still image without blur. However, there is a problem in that an iris is required when moving images can be taken, the structure is complicated and the cost is high. In the latter case, it is possible to use an iris instead of a shutter to shoot a still image, but there is a problem that the exposure time control accuracy cannot be obtained due to the restriction of the mechanical structure of the iris.

In view of the above problems, it is an object of the present invention to obtain a high exposure amount accuracy even when an iris is used, and therefore to obtain an electronic camera device for both operation and still images which has only the iris and no shutter.

[Means for solving problems]

The electronic camera device of the present invention is an electronic camera that selectively captures either a moving image or a still image, and an iris mechanism (2) for limiting the amount of light to a solid-state image sensor (CCD3)
And a calculation means (system controller 1 for calculating the aperture value and the exposure time of the iris mechanism (2) so that the exposure amount of the solid-state imaging device (3) becomes appropriate according to the incident light amount.
5) and the accumulated charge of the solid-state image sensor (3),
A read control means (video processing circuit (4)) for switching and controlling the read mode between a field mode for simultaneously reading the charges on the even and odd lines and a frame mode for alternately reading the charges on the even and odd lines; In the field mode, the aperture amount of the iris mechanism (2) is controlled so that the aperture amount has a predetermined value calculated by the calculation means (15), and
The exposure calculated by the calculating means (15) after the charge accumulated in the solid-state image pickup device (3) is controlled to be discarded and the read control means (4) controls the switching from the field mode to the frame mode. An exposure control unit that controls the exposure amount of the solid-state imaging device (3) by closing the iris mechanism (2) after a lapse of time is provided, and the iris mechanism ( The opening / closing of 2) is automatically controlled, the charge accumulated in the solid-state image sensor (3) is read out and controlled in the frame mode, and the opening state of the iris mechanism (2) is calculated by the calculating means during still image shooting. After the state of the set value is reached, the exposure control means controls the exposure amount, and the read control means controls the exposure amount of the solid-state imaging device (3). Reading out accumulated charges in a field alternately, characterized in that obtaining the frame still image signals.

According to this configuration, the aperture value and exposure time of the iris are calculated according to the amount of incident light to control the exposure amount of the image sensor.Therefore, it is appropriate to only control the opening or closing of the iris due to the mechanical structure of the iris. Even if the exposure amount cannot be controlled, the exposure amount can be controlled with high precision by combining it with the control of the aperture amount. In addition, effective exposure of the image sensor starts after the iris aperture is set and reading of the image sensor is prohibited, and ends when the iris is closed after the set exposure time elapses. Since the set time required for (value control) does not affect the effective exposure time, the exposure amount can be controlled at high speed and with high accuracy.

〔Example〕

FIG. 1 is a block diagram of a main part of a video still camera embodying the present invention, and FIG. 2 is a time chart showing its operation.

When used as a still camera, the image light that has passed through the lens 1 is adjusted in quantity by the iris 2 and then enters the CCD 3. Iris 2 also functions as a shutter,
It is closed at an appropriate timing to be described later in conjunction with the operation of the release button (that is, the shutter button) of the camera.

The charge of the CCD 3 is read by the video processing circuit 4 including the read control means of the image pickup device and transferred to the recording circuit 5. The output of the recording circuit 5 is given to the magnetic head 6 and recorded on the magnetic disk sheet 7.

When using as a video camera, changeover switch 9
From the still side to the VTR side, and the CCD output read by the video processing circuit 4 is led to the VTR 12 connected to the camera via the AGC amplifier 10 and the processing circuit 11.

The output of the AGC amplifier 10 is detected by the detector 13 and fed back to the AGC amplifier 12 as an AGC signal. Along with this, the output of the AGC amplifier 10 is also led to the detector 14, the average luminance signal indicated by the detected output is given to the system controller 15, and the control signal of the output is supplied to the iris motor 17 via the drive circuit 16. . As a result, auto iris control is performed in the direction of closing the iris 2 for a bright image and in the direction of opening the iris 2 for a dark image. The system controller 15 and drive circuit 16
Constitutes exposure control means.

Information about the iris opening obtained from the iris motor 17 is fed back to the drive circuit 16 to perform servo control so as to eliminate an error with respect to the control target value. The iris motor 17 is of a moving coil type, for example, and can obtain an iris opening proportional to the coil current value.
The opening degree information is obtained as an electric signal from a sensor such as a hall element.

Next, details of the operation as a still camera will be described with reference to the time chart of FIG.

In the case of a still camera, iris control is performed by the output of the light receiving element 18 that detects external light. The output of the light receiving element 18 is processed by the photometric circuit 19 and given to the system controller 15 as a detection signal. The system controller 15 calculates an appropriate aperture value F and exposure time T based on the detected photometric value. The system controller 15 may store an appropriate aperture value F corresponding to the photometric value and an exposure time in the form of a readable data table.

Press the shutter release button to open the system controller
Upon receipt of the release signal RS (FIG. 2E), 15 outputs a motor control signal to the drive circuit 16 and the output thereof drives the spindle motor 8. When the motor 8 starts up and the disc sheet 7 reaches a steady speed, the motor 8 obtains the same.
Field alternating two-phase drive signals SG1 and SG2 for CCD reading in synchronization with the PG signal (rotational phase signal) of FIG.
C) is formed by the drive circuit 16 and supplied to the video processing circuit 4.

The PG signal of FIG. 2A has a frame period, and its high level is an odd field and its low level is an even field. The drive signal SG1 is formed at the leading edge of the odd field, and the drive signal SG2 is formed at the leading edge of the even field. A read clock is generated in synchronization with these signals SG1 and SG2.

Along with this, the aperture value calculated by the system controller 15 is given to the drive circuit 16, and its output causes the iris motor
17 is driven and the iris 2 is opened as shown in FIG. 2F. The iris opening is set by servo control with the set aperture value as the target value. When Iris 2 opens,
Charge charge to CCD3 is started.

In this state, the CCD is in the field mode by the mode signal (high level) shown in FIG. 2D from the drive circuit 16. In this field mode, two adjacent odd and even lines of the CCD 3 are read in pairs. That is, all the charges of the CCD 3 are completely read out (discharged) for each field, and are read out and discarded without being recorded as shown in FIG. 2H.

After the opening of the iris 2 reaches the target F and vibration of the iris mechanism is established by the robot control, the mode signal is set to the frame mode (low level) at the timing of the drive signal SG1 as shown in FIG. 2D. Can be lowered. In this frame mode, the odd line group of CCD3 is read in synchronization with the drive signal SG1 and then the next drive signal is read.
The even line group of CCD3 is read in synchronization with SG2.

However, at the same time when the frame mode is entered, the transfer inhibit signal SG.CUT shown in FIG. 2G is formed by the system controller 15 and given to the drive circuit 16. This transfer prohibition signal has a width of 1 field or more and 1 frame or less. The drive signal SG2 of FIG. 2C included in this width becomes invalid, and CCD3 is read (transferred) until the prohibition signal returns to the low level. ) Will not be done.

Therefore, effective exposure to CCD3 starts immediately after entering the frame mode. Then, based on the time information T, the drive circuit 16 closes the iris 2 as shown in FIG. 2F when the proper exposure time T calculated by the system controller 15 based on the above-mentioned external photometric value has elapsed. Iris motor
Performs 17 controls. As a result, the shaded area in Fig. 2F is CC.
The effective exposure time T to D3 is reached, and the iris opening at this time is the proper aperture value F based on the above-described external photometry.

The iris opening (aperture value) is 0 to 100% depending on the photometric amount
Also, the exposure time changes from 0 to 1/30 second (1 frame). When the iris 2 is closed, there are actually fall times, overshoots, and undershoots peculiar to the servo system, but in consideration of these, the aperture amount, that is, the proper aperture value F and the proper exposure time T are calculated. There is.

When the iris 2 is closed and the exposure is completed, the transfer inhibit signal of FIG.
In synchronization with −O, as shown in FIG. 2H, the odd line group of CCD3 is read out as the CCD output o, and then the drive signal SG2−
In synchronization with E, the even line group is read out as the CCD output e.

The CCD output is derived from the video processing circuit 4 to the recording circuit 5 and given from the drive circuit 16 the odd field recording pulse (ODD-REC) of FIG. 2I and the even field recording pulse (EVEN-REC) of FIG. 2J. The recording circuit 5 operates at the timing of, and a recording signal is derived to the magnetic head 6. As a result, a still image is recorded using the odd field track and the even field track of the magnetic disk sheet 7.

In the embodiment, both the iris aperture value and the exposure time are controlled based on external photometry, but one is fixed,
The other may be changed so as to obtain an appropriate exposure amount according to the external photometric value. For example, the iris opening is fixed at 100% to control the exposure time, or the exposure time is adjusted to 1 /
It may be fixed to 60 seconds or 1/30 seconds, and the aperture value may be changed according to the photometric value. In this case, an iris knob or a shutter speed knob for manually changing the fixed value is provided, and the iris motor 17 is fixed so that either the iris value F or the exposure time T is fixed corresponding to the adjustment value of these knobs. May be controlled.

〔The invention's effect〕

As described above, the present invention controls the exposure amount of the image sensor by calculating the aperture value and the exposure time of the iris according to the incident light amount, so that only the control of opening or closing the iris is performed due to the mechanical structure of the iris. Therefore, even if the proper exposure amount control cannot be performed, high-precision exposure control can be performed by combining with the aperture amount control. In addition, effective exposure of the image sensor starts after the iris aperture is set and reading of the image sensor is prohibited, and ends when the iris is closed after the set exposure time elapses. Since the set time required for (value control) does not affect the effective exposure time, the exposure amount can be controlled at high speed and with high accuracy.
Therefore, it is possible to obtain an electronic camera device for both moving images and still images which does not require a shutter by using only the iris.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a video still camera showing an embodiment of the present invention, and FIG. 2 is an operation time chart of FIG. In the reference numerals used in the drawings, 1 ... Level 2 ... Iris 3 ... CCD 4 ... Video processing circuit 5 ... Recording circuit 6 ... Magnetic head 7 ... Magnetic disk sheet 8 ... Spindle motor 9 ... Change-over switch 15 System controller 16 Drive circuit 17 Iris motor 18 Light receiving element 19 Photometry circuit.

Claims (1)

[Claims] 1. In an electronic camera for selectively picking up either a moving image or a still image, an iris mechanism for limiting the amount of light to the solid-state image sensor, and an exposure amount of the solid-state image sensor is appropriate according to the amount of incident light. As described above, the calculation means for calculating the aperture value and the exposure time of the iris mechanism, the field mode for simultaneously reading the charges of the even lines and the odd lines with respect to the accumulated charges of the solid-state imaging device, and the charges of the even lines and the odd lines And a read control means for switching the read mode between a frame mode for alternately reading the field and the aperture amount of the iris mechanism so that the aperture amount is a predetermined value calculated by the calculating means in the field mode. At the same time, the charge accumulated in the solid-state image sensor is read out and controlled, and the read-out control unit controls the charge. Exposure control means for controlling the exposure amount of the solid-state image sensor by closing the iris mechanism after the exposure time calculated by the calculation means has elapsed since the field mode was switched to the frame mode. The iris mechanism is automatically opened / closed according to the amount of incident light when shooting a moving image, and the charge accumulated in the solid-state image sensor is read out in the frame mode.When shooting a still image, the aperture of the iris mechanism is opened. After the state becomes the state of the set value calculated by the calculating means, the exposure amount is controlled by the exposure controlling means, and the accumulated charge is alternately read from the solid-state image pickup device by the field to read the frame still image. An electronic camera device characterized by obtaining a signal.