JPS61284183A - Solid-state image pickup device with shutter function - Google Patents

Abstract

PURPOSE:To realize an ultrahigh-speed shutter function by a solid-state image pickup element itself to obtain still pictures of high resolution and high quality by using the image pickup element having two memory functions to perform the shutter control operation of 2:1 interlace scanning. CONSTITUTION:The electric charge of odd photodetector arrays 2a, 2b... as odd fields in a light reception electric charge generating part 1 is transferred to a memory 5 by a means 4 and is transferred to a memory 7 by a means 6. The electric charge of even photodetector arrays 3a, 3b... as even fields is transferred to the memory 5 and is transferred to the memory 7. The signal charge of odd and even fields are discharged from the memory 7 by an output means 8. In this case, odd/even photodetector arrays are switched and selected for the purpose of realizing 2:1 interlace scanning to execute the high-speed shutter function.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a solid-state imaging device having a shutter function that does not use a film or a light shielding mechanism such as a mechanical shutter.

(Background of the Invention) Conventionally, a solid-state image sensor has been capable of electronically realizing a shutter function by driving it, that is, an electronic shutter. Since it is not possible to capture a still image of a subject moving at high speed with high resolution, electronic still cameras using solid-state image carriers are used in combination with a mechanical shutter.

To explain in more detail the reason why a solid-state imaging device and a mechanical shutter are used in combination in this way, solid-state imaging devices have conventionally transferred and read out signal charges using 2:1 interlaced scanning, known as the television vision scanning method. This drive method does not cause any major problems when shooting moving images like a video camera, but when shooting still images, especially objects that move at high speed, like an electronic still camera, the resolution of the electronic shutter is lower. When taking a good photo, the image becomes blurry.

In other words, in order to obtain high image quality, it is necessary to obtain one frame image with signals for two fields consisting of an odd field and an even field. However, when a solid-state image carrier is driven using the television method, the odd field For example, the time difference between obtaining a signal and obtaining an even field signal is 1/60 sec.
In the case of a fast-moving subject, the lines of the subject are doubled due to the time delay of the field signal, resulting in a still image.

In order to prevent this blurring, it is sufficient to obtain only one field signal and perform field/frame conversion to convert the field signal into a frame signal by using this field signal twice. However, it is not possible to obtain a high-resolution, high-quality still image with a frame image in which one field signal is used twice.

Therefore, conventionally, it has been proposed to provide a mechanical shutter in front of a solid-state image sensor and realize a high-speed shutter by controlling the exposure amount by controlling the opening and closing of the mechanical shutter.

That is, the mechanical shutter is opened to expose all pixels of the solid-state imager to generate signal charges for one frame, and after the mechanical shutter is closed, the signal charges of all pixels are stored, and the odd field is first exposed. Transfer reading is performed, and then even-numbered field transfer reading is performed to obtain one frame of image.

(Problems to be Solved by the Invention) However, in such a conventional image carrier using a mechanical shutter and a solid-state image sensor, image blurring is likely to occur due to mechanical vibration caused by shutter operation.
Furthermore, in electronic still cameras that have the function of simultaneously recording audio, the loud operating noise of the shutter becomes a problem.

Furthermore, since solid-state imaging devices usually use an optical low-pass filter to prevent moiré, it is not possible to place a mechanical shutter just in front of the light-receiving surface of the solid-state imaging device, which reduces shutter efficiency. However, high-speed shutters had their limitations and required space, which was an obstacle to miniaturization.

(Object of the Invention) The present invention has been made in view of these conventional problems, and provides a shutter that does not require a mechanical shutter and is capable of high-speed shutter operation that allows high-resolution, high-quality still images to be obtained. The purpose of the present invention is to provide a solid-state image transfer device having the following functions.

(Summary of the Invention) In order to achieve this object, the present invention provides first and second charges that sequentially accumulate transfer charges for one field, which is 1q in 2:1 interlaced scanning, in the solid-state image carrier itself. A storage section is provided, and when the exposure time is reached, the odd number (first
) fields are transferred to the second charge storage section via the first charge storage section, and at the timing when the transfer of the signal charges of the odd field to the second charge storage section is completed, the even number ( 2) The light-receiving generated charge of the field is transferred to the first charge storage section, and the idle time for charge transfer between the first field and the second field from the light-receiving charge generation section is extremely short, which corresponds to the charge transfer time of two times. This prevents blurring of still images even when the shutter is operated at high speed due to time constraints.

(Example) FIG. 1 is an explanatory diagram showing a solid-state image sensor used in the present invention in functional blocks.

First, the configuration will be explained. Reference numeral 1 denotes a light-receiving charge generating section that generates charges upon receiving light from an object, and also has a function of holding the generated charges.

The light-receiving charge generating section 1 is an odd-numbered light-receiving element row 2a that is composed of a plurality of two-dimensionally arranged light-receiving element rows.

2b, 2c, . . . and even-numbered light receiving element rows 3a.

3b, 3c, . . . are arranged alternately in sequence.

4 is a first charge transfer means, and in order to realize 2:1 interlaced scanning in the television system, odd-numbered and even-numbered light-receiving element rows in the light-receiving charge generation section 1, for example, a light-receiving element row. 2a and 3a, and the signal charge obtained by one of the light receiving element rows is transferred to the first stage provided in the next stage.
The data is transferred to the memory 5 of. A second charge transfer means 6 is provided following the first memory 5, and transfers the odd or even signal charges accumulated in the first memory 5 to the second memory 7.

Here, the first memory 5 and the second memory 7 store signal charges for one field corresponding to the number of signal charges of odd-numbered light-receiving element rows or even-numbered light-receiving element rows in the light-receiving charge generation section 1. storage capacity.

Furthermore, a signal output means 8 is connected to the second memory 7, so that the contents of the second memory 7 can be taken out as a time-series signal.

In FIG. 1, parallel transfer is used to shorten the transfer time of the first and second charge transfer means 4.6, but time-series serial transfer may also be used.

FIG. 2 is a flowchart showing the shutter control operation of the solid-state image carrier used in the present invention, which has the functions shown in blocks in FIG. 1.

- When the shutter of the electronic still camera is released due to the dark shadow for a frame, the shutter control operation shown in the flowchart of FIG. 2 is started, and first blocks 9 and 1
Over a td time of 0.11, unnecessary charges that have been generated in the light-receiving charge generating section 1 are discharged.

That is, in block 9, the odd-numbered light-receiving element array 2a constitutes an odd-numbered field in the light-receiving charge generating section 1.

The charges 2b, 2C, . Subsequently, in block 11, even-numbered light-receiving element rows 3a, 3b,
3c, . The odd field charges previously transferred to the second memory 7 in block 10 are discharged to the outside before the even field signal charges are transferred by the signal output means 8. The even field charges transferred to are also discharged to the outside by the signal output means 8.

On the other hand, exposure of odd fields starts from the time of transfer to the first memory 5 shown in block 9, while for even fields, exposure starts from the time of transfer to the first memory 5 of block 11. , light-receiving charges are generated in accordance with the elapse of exposure time in odd-numbered fields and even-numbered fields in the light-receiving charge generating section 1, respectively.

Therefore, a delay time td occurs between the start of exposure of odd-numbered fields and the start of exposure of even-numbered fields, so the charge transfer of the first memory 5 shown in blocks 9 and 11 is made as fast as possible Timing delay time td must be kept to a minimum.

Next, in determination block 13, it is determined whether or not the exposure to the solid-state image element has reached the appropriate exposure amount using a separately provided photometry means.When the appropriate exposure amount is reached, the second exposure shown in blocks 14 onward is performed. charge transfer is performed.

That is, the light receiving element rows 2a, 2 which provide the odd field of the light receiving charge generating section 1 whose exposure was first started in block 14
The charges generated at points b, 2c, . . . are transferred to the first memory 5 by the first charge transfer means 4. At the time of the transfer to the "th" memory 5, the exposure of the odd field is completed, and the exposure time te1 is obtained. Next, in block 14, the odd field charges transferred to the first memory 5 are further transferred to the second memory 5.
The charge transfer means 6 transfers the charge to the second memory 7.

Next, in block 16, even-numbered light-receiving element arrays 3a, 3b, 3 that provide an even field in the light-receiving charge generating section 1 are arranged.
The generated charges of c, . . . are transferred to the first memory 5 by the first charge transfer generating means 4.

At the time of this transfer, the exposure of the even field is completed, and by matching the timing with the transfer of the odd field, the same exposure time te2 can be obtained for the even field.

Next, in block 17, odd field output is performed in which the odd field charges stored in the second memory 7 are outputted to the outside in time series by the signal output means 8, and when the odd field output is completed, the process proceeds to block 18. Second
The transfer means 6 transfers the even field charges accumulated in the first memory 5 to the second memory 7, and in the next block 19, the signal output means 8 outputs the even field charges in time series. End the shadow action.

As long as it has the charge transfer and charge storage functions shown in Figure 1 and the shutter control function shown in Figure 2, any solid-state image carrier can be used. For example, taking COD as an example, frame interline transfer COD can be used. In addition, in the case of a solid-state image carrier with a multilayer structure, the first layer serving as the surface layer becomes the light-receiving charge generating section 1, and the next second layer serves as the first and second layer.
It is conceivable that the memories 5 and 7 are used as the memories 5 and 7.

FIG. 3 is an explanatory diagram schematically showing a frame interline transfer COD as a solid-state imaging device that can be applied to the solid-state image pickup device having a shutter function of the present invention as clarified in the embodiments of FIGS. 1 and 2. Components corresponding to those in FIG. 1 are shown with the same reference numerals.

In the case of the frame interline transfer COD shown in FIG. 3, the data is transferred from the odd field light receiving element rows 2a to 2C and the even field light receiving element rows 3a to 3C to the vertical transfer section which becomes the first memory 58 to 5C. The time required for transfer is several microseconds, and the time required for transfer from the first memories 5a to 5C to the second memories 7a to 7C can be several tens of microseconds. The delay time td between odd and even fields given in the flowchart in the figure is extremely short, and a high-speed shutter operation of 1/10000 seconds or more can be realized.

FIG. 4 is a time chart showing the release pulse, transfer pulse, and external output pulse when the shutter control operation shown in FIG. 2 is performed for the frame interline transfer COD in FIG. After that, charge transfer to the first memory is performed by transfer pulse φ2 to discharge unnecessary charges in the odd field.

Subsequently, the transfer pulse φ4 transfers unnecessary charges to the second memory 7.
The data is transferred to the second memory 7 and discharged from the second memory 7 by an output pulse. Second memory 7 by transfer pulse φ4
When the transfer to is completed, the discharge of unnecessary charges in the odd field by the transfer pulse φ3 is similarly started.

Therefore, for odd-numbered fields, exposure is started from the time of transfer by transfer pulse φ2, while for even-numbered fields, exposure is started from the time of transfer by transfer pulse φ3 after delay time td.

Note that even during exposure, the transfer pulse φ4 and the output pulse φ5 are output as they are. Exposure time t for obtaining the appropriate exposure amount for the odd field where exposure is first started
When el has elapsed, a transfer pulse φ2 is issued again to transfer the odd field charges to the first memory 5, and then a transfer pulse φ4 transfers the charges from the first memory 5 to the second memory 7.
After this transfer is completed, a transfer pulse φ3 is generated to transfer the even field charges to the first memory 5.

Subsequently, the signal charge of the odd field is taken out from the second memory 7 by the output pulse φ5,
Furthermore, a transfer pulse φ is transferred from the first memory 5 to the second memory 7.
4, the even field charges are transferred, and finally the even field signal charges are taken out from the second memory 7 by the output pulse φ5.

Incidentally, the time chart in FIG.
A plurality of transfer pulses φ4 are used to transfer data to the memory 7, but if the first memory 5 and the second memory 7 are arranged adjacently in pixel units, transfer can be performed with one pulse. can be done.

Furthermore, the transfer pulses φ2 to φ shown in the time chart of FIG.
4 corresponds to the drive pulse of the frame incline transfer COD in FIG. 3, the transfer pulse φ2. φ3 corresponds to a transfer pulse from the light receiving section to the vertical transfer COD, transfer pulse φ4 corresponds to a transfer pulse for the vertical transfer COD, and output pulse φ5 corresponds to a transfer pulse for the horizontal transfer COD.

In the present invention, the charge structure from the first memory 5 to the second memory 7 and the transfer from the even-numbered light receiving column 3 to the first memory 5 are performed sequentially, but depending on the element, this may be done simultaneously in parallel. There is no problem even if this is done, and the transfer timing delay td can be further shortened by this.

(Effects of the Invention) As described above, according to the present invention, solid-state image carriers having first and second memory functions corresponding to odd fields and even fields in the light receiving charge generating section are used. Since the shutter control operation is performed using 2:1 interlace scanning, the difference in exposure time between odd and even fields is extremely short, and the solid-state image sensor itself realizes an ultra-high-speed shutter function, resulting in high resolution and high image quality. It is possible to realize a solid-state imaging device with a shutter function that can obtain still images, and eliminates image blur and shutter operation noise that were problems with conventional ratio imaging devices that also used a mechanical shutter. Therefore, it is particularly effective when used in devices such as electronic still cameras that require both high-speed shutter function and high image quality, or devices that require simultaneous operation of the shutter function and recording function.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the functional blocks of the solid-state image sensor used in the present invention, and FIG. 2 is a flowchart showing the shutter control operation of the present invention using the solid-state image sensor of FIG.
FIG. 3 is a schematic explanatory diagram of a frame interline transfer COD that can be used in the present invention, and FIG. 4 is a time chart showing a pulse signal that causes the frame interline transfer COD of FIG. 3 to perform the shutter control operation of the present invention. be. 1: Light-receiving charge generation section 2a, 2b, 2c: Light-receiving element row (odd field) 3
a, 3b, 3c: Light receiving element row (even field) 4:
First charge transfer section 5: First memory 6: Second charge transfer section 7: Second memory 8: Signal output means

Claims (1)

[Scope of Claims] An imaging device that sequentially outputs odd field signals and even field signals by 2:1 interlaced scanning includes: a light receiving charge generating section having a two-dimensional arrangement of a plurality of light receiving pixels; and the light receiving charge generating section. a first charge transfer means for transferring the signal charge for each field; a first charge storage section having a storage capacity for one field for accumulating the transfer charge from the first charge transfer means; a second charge transfer means for transferring the signal charges of the first charge accumulation section; a second charge accumulation section having a storage capacity for one field for accumulating the transferred charges from the second charge transfer means; , a signal output means for sequentially outputting a signal according to the signal charge from the second charge storage section in time series on a field-by-field basis; The odd field signal charges generated in the light receiving charge generating section of the first
The signal charges of the even field generated in the photodetection charge generation section are transferred to the second charge storage section via the charge storage section of What is claimed is: 1. A solid-state imaging device having a shutter function, characterized in that it is provided with electronic shutter control means for transferring charge to one charge storage section.