JPH10257382A - Electronic camera - Google Patents

Abstract

(57) Abstract: An inexpensive electronic camera capable of multiple exposure using a consumer CCD solid-state imaging device is realized. In a CCD solid-state imaging device, 1
A plurality of exposures within a frame are performed, and the signal charges of the photodiodes at each exposure are transferred to a vertical transfer CCD register and accumulated, and the accumulated signal charges are read out to generate a video signal. The video signal is such that the trajectory can be understood.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electronic camera, and more particularly to an electronic camera suitable for recording (photographing) an optical image of a moving subject at high speed by converting it into a video signal using a solid-state imaging device. .

[0002]

2. Description of the Related Art A CCD solid-state imaging device used as a photoelectric conversion device in an electronic camera is, for example, a "solid-state imaging device", 17th edition of Shokodo, edited by The Institute of Television Engineers of Japan.
As disclosed on page 0 to, a CCD register for vertical transfer of signal charges obtained by performing photoelectric conversion by exposing photoelectric conversion elements (photodiodes) arranged at equal intervals on a two-dimensional plane with a light image is disclosed. And read the vertical transfer CCD
The signal charges read to the register are sequentially transferred to the horizontal transfer CC.
The configuration is such that a video signal for one frame is generated by serially outputting from the horizontal transfer CCD register while transferring to the D register.

FIG. 1 shows an interline type CCD (IT-
CCD) solid-state imaging device, a vertical synchronization signal VD, a vertical transfer CCD (V-CCD) register, and a substrate (SU).
4B shows a drive voltage waveform. Substrate drive voltage SUB
Is set to the “+ H” level, and the charges (signal charges) accumulated in the photodiodes by the exposure after sweeping out the charges accumulated in the photodiodes are changed to “+ VH” by the vertical transfer driving voltages V1 and V3. By applying a level read drive voltage, the photodiodes are transferred from each photodiode to the vertical transfer CCD register area. Thereafter, by controlling the timing of changing the signal charges of the vertical transfer CCD register to the voltages of the vertical transfer drive voltages V1 to V4 to the "-potential" level, the signal charges are first mixed and then sequentially transferred vertically. The video signal is transferred to the horizontal transfer CCD register and serially output from the horizontal transfer CCD register to generate a video signal for one image (one frame).

In a still camera that handles still images, such a video signal is captured for one frame every time the shutter button is pressed and recorded one-shot, and in a video (movie) camera that handles moving images, the shutter button is pressed. While the recording is being performed, the data is repeatedly captured at a predetermined cycle and continuously recorded.

[0005]

SUMMARY OF THE INVENTION Such conventional CCs
In the D-type solid-state imaging device, reading from each photodiode (transferring the signal charge accumulated in the photodiode to the CCD register for vertical transfer) for generating a video signal constituting one image (one frame) is one. Times. Therefore, when an image signal is generated by photographing a rapidly moving subject, the read cycle of a general CCD solid-state imaging device is 1/60 s even if the shutter speed (exposure time) is set to 1/500 s, for example. Therefore, it is difficult to accurately capture a moment at which a phenomenon that changes in less than 1/60 s is captured unless synchronization is established.

In order to solve such a problem, a method of increasing the read cycle has been proposed. However, this method has a problem that power consumption is increased due to an increase in driving frequency, and furthermore, a high speed operation is required. A special CCD-type solid-state imaging device that operates on a PC is required, and becomes expensive. In addition, an imaging method in which a shutter is released in synchronization with the movement of a subject can be considered, but a device for synchronization is required, and the apparatus becomes complicated.

One object of the present invention is to provide an electronic camera which is convenient for photographing an object moving at high speed using a general CCD type solid-state imaging device in consideration of the above points. It is in.

Another object of the present invention is to provide an electronic camera which is convenient for photographing so that the locus of movement of an object moving at high speed can be understood.

It is still another object of the present invention to provide an electronic camera which can selectively execute photographing for clearly recording a subject and photographing for recording so that a locus of movement can be recognized.

It is still another object of the present invention to provide an electronic camera capable of executing the above-described shooting in a moving image shooting (video camera shooting) mode and a still image shooting (still camera shooting) mode. .

[0011]

According to the present invention, in a CCD type solid-state imaging device, reading of signal charges generated by a photoelectric conversion element to a transfer section (movement of signal charges = exposure) is performed in a plurality of times. By accumulating the signal charges obtained by reading in the transfer unit, multiple exposures by the subject are realized, and signal charges (video signals) corresponding to the locus of the subject moving at high speed can be obtained.

The exposure time of a CCD solid-state imaging device is
This is a photoelectric conversion time for generating a signal charge in a photodiode serving as a photoelectric conversion element. The photoelectric conversion time (exposure time) is obtained by performing a sweeping operation of sweeping out charges generated by photoelectric conversion by the photodiode to the substrate, and then transferring charges generated by photoelectric conversion by the photodiode to a vertical transfer portion as a transfer portion. This is the time until the signal is read out to the CCD register as signal charge. The multiple exposure is realized by performing control of repeating a charge sweeping operation and a reading operation a plurality of times for the photoelectric conversion element. Therefore, the time from a single sweep operation to a read operation (multiple exposure time) in multiple exposure is equal to the exposure time (total exposure time) required to obtain one image (one frame of video signal). It is the time divided by the number of repetitions. And
The respective partial exposures (partial exposure times) are set so as to be evenly distributed within a photographing period for obtaining one image.

The total exposure time varies depending on the illuminance of the subject and the amount of aperture. In order to secure the changing total exposure time, there are a method of changing each partial exposure time and a method of changing the number of repetitions of the partial exposure according to the illuminance and the aperture of the subject.

In order to convert (photograph) the image signal so that the movement locus of the object can be understood, it is desirable to perform control such that the higher the moving speed of the object, the greater the number of repetitions of the partial exposure.

In an automated electronic camera, the illuminance of a subject is automatically measured, and the aperture and the total exposure time are automatically calculated by a controller. Therefore, based on the calculation result, the number of times of partial exposure repetition and each partial exposure time can also be automatically calculated by the control device according to a predetermined setting method, and its optimum value can be obtained.

The number of repetitions of the partial exposure may be fixedly set in advance, or may be set to be changeable.
A method of setting the number of times of repetition of the partial exposure to be changeable according to the moving speed of the subject is a means for automatically measuring and setting the moving speed of the subject or a means for manually setting a value visually determined by an operator. Can be realized by providing

An electronic camera capable of selecting a shooting function in a video camera (moving image shooting) mode or a still camera (still image shooting) mode includes shooting for continuously recording a video signal in the form of a video signal; It is possible to selectively execute one-shot recording of one frame of a video signal in a still image form.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows a vertical synchronizing signal VD and a CCD for vertical transfer in a CCD type solid-state imaging device according to the present invention.
(V-CCD) shows a driving voltage waveform of a register, a reading gate (SG), and a substrate (SUB). FIG. 3 shows V-CCD, PD (photodiode), SG and SU at each timing of t _{1 to} t ₈ in FIG.
4 shows the potential distribution of B and the movement of charges generated by photoelectric conversion. FIG. 4 is a block diagram showing the configuration of the electronic camera according to the present invention.

The electronic camera shown in FIG. 4 has a moving image photographing function (video camera function) and a still image (single frame) photographing function (still camera function), and these two functions can be selectively used. It is an electronic camera.

In FIG. 4, reference numeral 1 denotes a photographing lens, 2 denotes an iris (aperture), and 3 denotes a CCD type solid-state imaging device.
The CCD solid-state imaging device 3 includes a photoelectric conversion unit that converts a light image of a subject illuminated on a two-dimensional surface into electric charges by a large number of photoelectric conversion elements (photodiodes) provided on the two-dimensional surface. A transfer unit (a transfer CCD register) to which the charge generated by the photoelectric conversion unit is transferred to a transfer region by a read pulse and is stored as a signal charge, and the stored signal charge is transferred by the transfer pulse; And a sweeping section for sweeping out the charges generated in the substrate as unnecessary charges to a substrate by a sweeping pulse, and generating a video signal for one frame by transferring the signal charges by the transfer section. This is the same as a conventional general CCD-type solid-state imaging device that photoelectrically converts a light image of a passed subject and outputs a video signal.

Reference numeral 4 denotes a control device mainly composed of a microcomputer, which comprises a signal processing unit 4a and a control processing unit 4b. However, in the control device 4, some processing functions (parts) necessary for high-speed signal processing, such as a video signal integration function (part) described later, are realized using dedicated hardware. Good.

The signal processing section 4a edits a video signal output from the CCD type solid-state imaging device 3 into a moving image recording signal form or a still image recording signal form by using the memory 5 to convert a magnetic tape or a magnetic disk. It has a function of recording on the used recording device 6 and detecting the exposure amount (illuminance of the subject) by integrating the video signal.

The control processor 4b calculates the shutter speed (exposure time) of the CCD solid-state imaging device 3 and the aperture of the aperture 2 according to the exposure detected by the signal processor 4a, and inputs control information. In accordance with input information from the device 7, control information for controlling the signal processing 4a, the CCD solid-state imaging device 3, and the recording device 6 is generated.
The detailed control processing function of the control processing unit 4b will be described later.

The control information input device 7 includes a photographing mode setting means 7a for setting and inputting whether the electronic camera is to be used for a video camera or a still camera, and an exposure method of either single exposure or multiple exposure. An exposure method setting means 7b for setting and inputting whether to operate, a speed information input means 7c for inputting moving speed information of a subject, and a shutter button 7d for instructing a photographing operation are provided. Exposure method setting means 7b
The multi-exposure method includes an input unit for setting whether the number of exposures is to be set manually or automatically, and a number input unit for manual setting. Further, the speed information input means 7c analyzes the video signal obtained by manually photographing the subject or a manual input means by which the operator visually determines (for example, high speed, medium speed, low speed) and inputs the moving speed of the subject. Automatic input means for detecting the moving speed of the subject can be used.

It should be noted that such a control information input device 7
It is convenient to adopt a configuration in which a selection is input from a setting menu displayed using a liquid crystal panel.

Numeral 8 is a timing generating means, which is a driving voltage (V1 to V4) for driving the CCD solid-state imaging device 3 based on control information input from the control processing section 4b.
VH, SUB) are generated, and the timing pulses are generated by the voltage converter 9 to drive voltages (V1 to V1).
4, VH, SUB) to drive the CCD solid-state imaging device 3. The timing generator 8 and the voltage converter 9 can be integrally formed with the CCD solid-state imaging device 3 as necessary.

FIG. 5 is a functional block diagram of the timing generating means 8. This timing generating means 8 is mainly composed of a counter and a count output characteristic setting circuit.
It includes a vertical synchronizing signal generator 8a, a vertical transfer CCD timing pulse generator 8b, a substrate drive timing pulse generator 8c, a horizontal transfer CCD timing pulse generator 8d, and a read pulse timing setting unit 8e.

The vertical synchronizing signal generator 8a counts the reference clock signal CLK to generate a vertical synchronizing signal VD.

When the vertical synchronizing signal VD is input, the vertical transfer CCD timing pulse generator 8b counts the clock signal CLK and counts the timing pulses for the vertical transfer driving voltages V1 to V4 and the read driving voltage VH. Generate a timing pulse for The timing pulse for the read drive voltage VH is set in the read pulse timing setting unit 8e based on the timing control information obtained by the control processing unit 4b according to the exposure time (shutter speed) and the number of exposures. It is generated by controlling the operation characteristics of the timing pulse generator 8b.

Substrate driving timing pulse generator 8c
Generates a timing pulse for the substrate drive voltage SUB according to timing control information obtained and set by the control processing unit 4b in accordance with the exposure time (shutter speed) and the number of exposures in synchronization with the vertical synchronization signal VD. Output.

The multiple exposure operation in the electronic camera having the structure shown in FIG. 4 will be described with reference to FIGS.
Here, the CCD solid-state imaging device 3 mixes adjacent upper and lower pixels in a complementary color filter (for example, Mg, Cy, Ye, G) array, and outputs signals of all pixels in one field (1/6).
0-s) IT-CCD (interline type CC)
D) type solid-state imaging device.

Light from a subject incident through the taking lens 1 is incident on a photodiode (PD), which is a photoelectric conversion element of a photoelectric conversion unit in a CCD solid-state imaging device 3, via a stop 2. This incident light is converted into a video signal by the CCD solid-state imaging device 3 and input to the signal processing unit 4 a of the control device 4. Signal processing unit 4a
Detects the amount of exposure (illuminance of the subject) by integrating this video signal.

The control processor 4b fetches the information of the exposure amount, and when the information exceeds the standard illuminance, the aperture 2
The shutter speed (total exposure time) faster than the 1/60 s readout cycle of the CCD solid-state imaging device 3 is determined. At this time, if, for example, the shutter speed (total exposure time) required for shooting one frame is 1 / 250s, in the multiple exposure method, for example, if the number of partial exposures in one frame is set to five, The partial exposure time per time is (1/250)
/ 5 = 1/1250 s.

On the other hand, the vertical transfer C
Since the number of times of reading signal charges from the CD register is five per frame, (1/1 /
60) / 5 = 1/300 s.

In such an electronic camera, the difference between each exposure interval of 5 times and each partial exposure time within each frame (one field period) (1 / 300-1 / 1250 = 19 /
7500 s), the substrate drive voltage SUB is set to the “+ H” level, and the operation of sweeping out the charges (electrons) due to the photoelectric conversion stored in the photodiode PD to the substrate is performed (timing t ₁ in FIGS. 2 and 3).

Next, the substrate drive voltage SUB is set to the "L" level, and the photodiode P is set for a period of 1/1250 s.
The partial exposure for storing the photoelectrically converted charges in D is performed (timing t ₂ in FIGS. 2 and 3).

Immediately after this (at the end of the partial exposure time), the drive voltages V1 and V3 are set to the "+ H" level to set the read gate SG between the photodiode PD and the V-CCD register.
The Open transferring the signal charge of the photodiode PD to the V-CCD register area corresponding to the driving voltage _{V1, V3 (t 3, t} 4 in FIG. 2, FIG. 3).

By repeating this series of operations five times, the signal charge due to the partial exposure of 1/1250 s is reduced to 1/3.
It is generated five times at intervals of 00 s and is accumulated in the V-CCD register area corresponding to the drive voltages V1 and V3. afterwards,
The signal charges (pixels) in the V-CCD register area corresponding to the drive voltages V1 and V3 are mixed and sequentially output to the output terminal of the CCD solid-state imaging device 3 by a normal readout method to obtain a video signal. The video signals (images) output in this manner appear as if five images are superimposed on a moving subject, and represent a locus of motion.

The control processing section 4b of the control device 4 is configured (programmed) to perform the following control processing in accordance with the setting input information from the control information input device 7 in order to operate the electronic camera.

(1) Calculation of aperture and shutter speed (exposure time) and its control Obtain exposure amount information from the signal processing unit 4a, and calculate the aperture amount and shutter speed (exposure time per frame = total exposure time). Ask. The iris 2 is controlled based on the aperture amount information. The total exposure time information is used for exposure control described later.

(2) Setting of shooting mode (video camera / still camera) and its control It is checked whether the setting input from the shooting mode setting means 7a is the video camera mode or the still camera mode. In the case of the video camera mode, the signal processing unit 4a is instructed to edit a video signal input from the CCD solid-state imaging device 3 into a video signal format and output the video signal, and to the recording device 6 While the shutter button is pressed, an instruction is given to continuously record the video signal output from the signal processing unit 4a. In the case of the still camera mode, the signal processing unit 4a receives C
Instructs the video signal input from the CD-type solid-state imaging device 3 to be edited into a still image recording signal format and output;
The recording device 6 is instructed to record one frame of the video signal obtained immediately after the shutter button is pressed.

(3) Exposure method setting (single exposure / multiple exposure) and its control It is checked whether the setting input from the exposure method setting means 7b is a single exposure or a multiple exposure. In the case of the single exposure method, since the reading of the CCD solid-state imaging device 3 is performed once for each frame, the sweeping and reading are performed once for each frame (the total exposure time).
Controls the timing generation means 8 to generate timing pulses for generating drive voltages V1 to V4, VH, and SUB for driving the CCD solid-state imaging device 3 so as to generate a video signal.

In the case of the multiple exposure method, it is confirmed whether the number of partial exposures is set manually or automatically. In the case of manual setting, the number of partial exposures set or input from the number-of-times input means or the number of partial exposures fixedly set in advance is set as the number of multiple exposures. In the case of automatic setting, the number of partial exposures is obtained and set by referring to the total exposure time and subject speed speed information described later. In order to shoot and record the moving trajectory of the subject moving at high speed in detail, it is desirable to increase the number of partial exposures as the moving speed of the subject increases.

(4) Input of object speed information The input information from the speed information input means 7c is obtained. In the case of manual input, speed information (for example, high speed / medium speed / low speed) input by the manual input means is acquired, and in the case of automatic input, a video signal obtained from the signal processing unit 4a is analyzed to obtain a subject. Find the moving speed of

(5) Photographing The signal from the shutter button 7d is monitored, and when a signal indicating that the shutter button is pressed is detected, in the case of the video camera mode, the signal is output during the time the shutter button is pressed. The recording device 6 is controlled so as to continuously record a video signal in the form of a video signal generated by the processing section 4a. In the case of the still camera mode, the still image signal in the form of a still image signal obtained immediately after the shutter button is pressed. The recording device 6 is controlled so that the video signal for one frame is recorded once.

In the above embodiment, a pixel-mixing type IT-
As described in the example using a CCD type solid-state imaging device,
The present invention can be similarly implemented in a so-called all-pixel reading CCD solid-state imaging device in which charges of all photodiodes are sequentially read out without mixing pixels.

[0048]

As described above, according to the present invention, an object that moves at high speed can be obtained by using a general-purpose inexpensive CCD solid-state imaging device without using a special CCD solid-state imaging device. An electronic camera suitable for photographing can be realized. Specifically, a multiple-exposure object can be photographed in such a manner that a moving object at a high speed can be recognized in a locus of movement of the object.

Further, the present invention selectively uses a photographing mode by a single exposure for clearly recording a moving subject and a photographing mode by a multiple exposure for recording so that the moving locus of the subject can be recognized. The combined shooting can be performed.

Further, the exposure control according to the present invention can be applied to both recording methods of still image recording and moving image recording to perform photographing according to the purpose of photographing.

[Brief description of the drawings]

FIG. 1 shows a conventional vertical synchronization signal, a vertical transfer CCD register, and a substrate (SU) in an IT-CCD solid-state imaging device.
It is a figure which shows the drive voltage waveform of B).

FIG. 2 is an IT-CCD in an electronic camera according to the present invention.
Vertical synchronization signal for solid-state imaging device and C for vertical transfer
FIG. 4 is a diagram showing drive voltage waveforms of a CD register and a substrate.

FIG. 3 shows C at each of timings t _{1 to} t ₈ in FIG. 2;
FIG. 3 is a schematic diagram illustrating a state of movement of charges of the CD-type solid-state imaging device.

FIG. 4 is a block diagram showing an embodiment of an electronic camera according to the present invention.

5 is a block diagram of a timing generation unit in the electronic camera according to the present invention shown in FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photographing lens 2 iris (aperture) 3 CCD solid-state imaging device 4 control device 4 a signal processing unit
4b: control processing unit, 6: recording device, 7: control information input unit, 8: timing generation means.

Claims (13)

[Claims] An optical image of a subject illuminated on a two-dimensional plane is
A photoelectric conversion unit for converting into electric charges by a large number of photoelectric conversion elements provided in a three-dimensional plane, and electric charges generated in the photoelectric conversion units are transferred to a transfer region by a read pulse and accumulated as signal electric charges; Using a solid-state imaging device including a transfer unit in which the transferred signal charge is transferred by a transfer pulse, and a sweep unit that sweeps out the charge generated in the photoelectric conversion unit as unnecessary charge to a substrate by a sweep pulse. An electronic camera that generates a video signal for one frame by transferring a signal charge, wherein the charge generated in the photoelectric conversion unit is stored as a signal charge in the transfer unit in order to accumulate the signal charge for one frame in the transfer unit. It is preferable that the read operation for transferring and the sweeping operation for sweeping out the charge generated in the photoelectric conversion unit as unnecessary charge be repeated several times. An electronic camera, further comprising a solid-state imaging device control means for controlling the reading operation and the sweeping operation. 2. An electronic camera according to claim 1, wherein said solid-state imaging device control means controls said read-out operation and sweep-out operation in accordance with an exposure time per frame corresponding to the illuminance of a subject. 3. The electronic camera according to claim 2, wherein said solid-state imaging device control means changes a time from each sweeping operation to a reading operation in accordance with said exposure time. 4. An electronic camera according to claim 1, wherein said solid-state imaging device control means changes the number of repetitions of a read operation and a sweep operation per frame according to a moving speed of a subject. 5. The electronic device according to claim 1, wherein said solid-state imaging device control means controls each read operation and sweep operation in accordance with an exposure time obtained in accordance with the illuminance of the subject and the aperture amount. camera. 6. The solid-state imaging device control means according to claim 1, wherein the read-out operation and the sweep-out operation per one time are controlled in accordance with an exposure time obtained in accordance with the illuminance of the subject and the aperture amount. And electronic camera. 7. The solid-state imaging device control means according to claim 5, wherein said solid-state imaging device control means changes the number of repetitions of a read operation and a sweep operation per frame in accordance with an exposure time obtained in accordance with an illuminance of the subject and an aperture amount. An electronic camera characterized by the following. 8. An electronic camera according to claim 1, wherein said solid-state imaging device control means includes setting means for manually setting the number of repetitions of said read operation and sweep operation. 9. An electronic camera according to claim 1, wherein said solid-state imaging device control means includes a setting means for setting the number of repetitions of a read operation and a sweep operation in accordance with a moving speed of a subject. 10. An electronic camera according to claim 9, wherein said solid-state imaging device control means automatically detects the moving speed of the subject and automatically sets the number of repetitions of the reading operation and the sweeping operation. . 11. An electronic camera according to claim 1, further comprising a recording device for selectively recording the video signal either continuously or spontaneously. 12. The apparatus according to claim 1, further comprising signal processing means for selectively editing a video signal output from said solid-state imaging device into a video signal format of a video signal format or a still image signal format. Electronic camera featuring. 13. The solid-state imaging device control means according to claim 1, wherein a sweeping operation and a reading operation for obtaining a video signal for one frame from said solid-state imaging device are selected from a single operation and a plurality of operations. An electronic camera, comprising: means for dynamically setting.