JPS5847376A - Frame transfer type image pickup element - Google Patents

Abstract

PURPOSE:To permit a frame transfer type image pickup element to operate as a normal video camera for continuous image pickup, by providing a storage part wherein charges are stored in combination to generate an image picture for a share of one picture element, and increasing the capacity of the storage part according to charges. CONSTITUTION:In the 1st field, charges stored in parts (1,1)-(1,4) are transferred to parts [4,1]-[4,4] of a storage part. Then, charges are transferred from parts (2,1)-(2,4). At this time, no pulse voltage is applied to the storage part 3 and when the last one resides, two columns of an image pickup part 1 and added at this cell. After one-line transfer of the storage part 3, two rows of charges of the image pickup part 1 are transferred. Thus, the 1st field is read and then the next field is read. In this case, the cell to be added is shifted by one row and operation is carried out to perform addition between (2,1) and (3,1), and (4,1) and (5,1), thereby obtaining the last field and an interlaced signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frame transfer type solid-state image sensor (hereinafter abbreviated as CCD) K, and particularly to a solid-state image sensor structure that can be used for both high-resolution still image and video shooting. In the conventional frame transfer type area sensor, the number of cells in the vertical direction of the imaging section is 245 cells, which is about half of the 525 scanning lines in the case of the NTSC system.
Also, since each cell has a photosensitive and transfer function, the number of feed elements that can be stored at one time is 245, that is, 1
After reading out the signal charge for one field, the effective photosensitive area of each cell is moved and imaged, and this one field is read out next. This system was very compatible with the NTSC television system, and despite having a small number of cells, it produced an image with excellent resolution. It has the characteristics that can be obtained.

On the other hand, in recent years, there has been research and development into using image sensors such as COD instead of conventional silver halide film, called video still cameras or video photography, to capture images and record them magnetically. Ta.

If a conventional frame transfer type area sensor is used in such a system, it will consist of two fields separated by 1/60 seconds, which will be unsightly if a moving subject is imaged. Only an image can be obtained, and if such development is avoided and one field recording is performed, the resolution in the vertical direction is reduced to about half.

The present invention improves such conventional drawbacks and provides a structure for an imaging device such as a COD that is capable of frame recording suitable for a video still camera and also capable of normal television operation. .

The present invention will be described below with reference to the drawings and embodiments. 1st
The figure is a diagram showing the configuration of a frame transfer type COD according to the present invention. 1 in the figure is a frame transfer type COD imaging unit 0. For example, in the case of the NTSC system, the number of cells in the vertical direction is approximately equal to the number of scanning lines, 490.
It is set to a certain degree.

In other words, it has about twice the number of cells as the conventional frame transfer type COD. The number of cells in the horizontal direction is usually about 390 or 570, which corresponds to the color sub and carrier frequencies. FIG. 1 shows only 9 and 4 of these elements, respectively. Further, reference numeral 2 in the figure is an electrode for applying a voltage to the imaging section for receiving and transmitting light.

Reference numeral 6 denotes a storage section, and the number of cells in the vertical direction is approximately equal to the IA of the imaging section, and the number of cells in the horizontal direction is equal to that of the imaging section. Therefore, this storage section is approximately equivalent to the conventional frame transfer type COD. 04 is an electrode to which a voltage is applied for transferring charges. Reference numeral 5 designates a horizontal transfer register, which is configured as a line of charge transfer units having approximately the same number of cells in the horizontal direction as the number of cells in the imaging section and storage section. O7, which is an electrode to which a voltage is applied, is an amplifier that converts the charge transferred from the horizontal transfer register 5 into a voltage output.

Conventionally, charge transfer methods include single-phase drive, two-phase drive,
There are several methods such as three-phase drive and four-phase drive, and any of them can be adopted in the COD configuration of the present invention, but as a single-phase drive method, for example,
Any method such as that described in Publication No. 94 may be used.

FIG. 2 is a schematic plan view of the imaging device according to the present invention.
indicates a channel stop to prevent charge leakage between cells in the horizontal direction, and the shaded area 21 indicates a polysilicon electrode in the imaging section, and this electrode is located in the first region (1) with different potential states in the silicon. and a second area (It).

Reference numeral 22 denotes a virtual electrode formed in silicon, forming a sixth region (110 and fourth region) having different potential states in silicon.

One cell in the vertical direction is composed of the first to fourth regions.

24 and 25 are configured in the same manner as 21 and 22 of the imaging section.

FIG. 6 is a diagram showing the internal potential state of the COD having the configuration shown in FIG.

Reference numeral 60 indicates a polysilicon electrode of the imaging section corresponding to 21 in FIG. Below the polysilicon electrode 30, as explained in FIG. The solid line in the figure indicates a state where the polysilicon electrode 30 has a high negative potential, and the dotted line indicates a state where the polysilicon electrode 30 has a high negative potential. The 30 potentials represent slightly negative or positive state potentials, respectively.

As shown in FIG. 3, the potential of the virtual electrode portion 22 in FIG. 2 is much higher in the sixth region than in the fourth region. Further, the potential of this portion does not depend on the voltage applied to the electrode 30 and is always kept constant. Therefore, by applying a constant voltage to the polysilicon electrode, charges are accumulated, and by applying a pulsed voltage, the charges are sequentially transferred.

In FIG. 3, numeral 32 indicates a polysilicon electrode of the storage section. The internal potential of this storage section is formed substantially the same as that of the imaging section.

Note that t', n', m', and rv' correspond to the first to fourth (1 to ■) regions of the potential of the imaging unit.

Furthermore, in the present invention, since the capacitances of the second potential regions ■' and ■' in the storage section are set large as shown in the figure, the influence of noise caused by dark current, etc. in the storage section can be kept relatively small. This has the effect of increasing the S/N ratio.

In FIG. 3, numeral 33 indicates a horizontal transfer register, one side of which is closed with a channel stop. 64 indicates the potential state of the channel stop portion.

Next, the movement of charges will be explained based on FIGS. 1 to 6.

The charges accumulated in the imaging section are transferred by applying a pulse voltage to the polysilicon electrode 50, and enter the fourth potential region 25 in FIG.

At this time, when a slight negative or positive potential is applied to the polysilicon electrode 30, the potential state shown by the solid line in the third figure is achieved, and the charges in the fourth region enter the second region through the first region. Next, when a high negative potential is applied to this electrode 30, the charge in the second region is transferred to the
’ area is transferred.

At this time, if a slight negative or positive potential is applied to the polysilicon electrode 32 of the storage section, this region 1'
The potential of the l' region decreases, and the charges accumulated in the ■' region are transferred to the u' region. By repeating this process, the charges transferred to the storage section are transferred to the polysilicon electrode 32 of the storage section. The data is transferred to the horizontal transfer register by applying a cursor-like voltage, and the horizontal transfer register is then explained with reference to FIG. 4 (using at + (b+)).

Figure 4(a) is an operating state diagram when operating as a video/still camera for taking still images, and Figure 4(b) is an operating state diagram when operating as a conventional video camera for taking continuous images. In the state (a-1) in Figure 4 (a), which shows the state diagrams, unnecessary charges accumulated by dark current etc. immediately before the exposure operation are removed through the anti-pluming drain.
Or all-ri 1 to drive COD at high speed and clear it
0 Showing the Noah state Next, a shutter (not shown) opens and the state shifts to the exposure state or the accumulation state of the imaging section (a-2) 0 After the shutter closes, the state shifts to the state (a-3) and the accumulation The resulting charges are, for example, (1, 1) and (1, 2) in FIG.

The signal charge accumulated at (1, 3), (1, 4) is (
4,1), [4,2), (4,3), (4,4), (
2,1).

The signal charges accumulated at (2,2), (2,3), (2,4) are (1,1), (1,2), (1,, lS), (1
, 4), the signal charges accumulated in other picture elements are similarly shifted. This is repeated sequentially, and from the horizontal register (1, 1), (1, 2)... (9, 3), (9, 4
) The signal charges can be output as a time-series signal.

In this case, the signal charge from (1,1) to (4,4) is (
It is also possible to transfer at a frequency different from the readout frequency until moving from 1, 1) to (4, 4). In this way, a still image signal for one frame at the same accumulation point is obtained. I can do things.

Next, we used this device for normal continuous shooting video.

The operation when operating as a camera will be explained.

The state of (b-1) in Figure 4 (1)) is the state of (a-1) in (a).
) indicates an all-clear state corresponding to the operation.

However, this operation is not essential.

Further, in this case, a shutter is not necessary, and the operation is performed by alternately repeating storage and reading. (b 2) + (b-2)
'...indicates the accumulation state, and the darashi symbol indicates the second field. In other words, the charge accumulated at (b-2) is read out at (b-3), and the charge accumulated at (b-2) is read out at (b-3). 2)
The charges accumulated in ' are read out in (b-3)', respectively. The state (b-4) indicates a state in which the charges accumulated in the imaging section are transferred to the storage section.

This frame transfer type COD according to the present invention has 490 cells in the vertical direction of the imaging section and 245 cells in the storage section, so it is different from the normal frame transfer type COD in terms of the operation and interface when transferring from the image pickup section to the storage section. The racing methods are different. This operation will be explained using FIG. 1.

First, the first field is (1,1), (1,2).

The charges accumulated in (1, 3), (1, 4) are transferred to (4, 1), (4, 2), (4, 3), (4, 4) of storage section 3.
will be forwarded to. Then (2,1), (2,2), (2,
Similarly, the charges of 3) and (2°4) become [4,1) and (4
, 2), (4°3), and (4,4). At this time, no pulse voltage is applied to the storage section, and the previous one remains as it is (if done in a filtered manner, two pulse voltages are applied to the imaging section in this cell).
The columns will be added.

Next, one line of the storage section is transferred, and then two lines of the imaging section are transferred, as described above. After reading the first field in this way, when reading the next field, shift the cells to be added by one line, and (2, 1) and (3,
1), (4,1), and (5,1) are respectively added, it is possible to obtain a signal interlaced with the previous field.

As explained above, according to the imaging device of the present invention, it is possible to operate exactly the same as a conventional video camera for normal continuous shooting.

In addition, the present invention provides 1 in video/still camera operation.
It has an excellent ability to obtain high quality image signals for one frame.

In addition, if the subject does not move, it is possible to extract the signal for two frames by moving the picture elements field by field within one cell as in the conventional method. .

In addition, since the image information corresponding to each pixel is obtained by combining the charges of multiple photoelectric conversion units, it is possible to obtain smooth lines down to the details of the image when forming multiple field frames. Imaging using the interline method is possible, so 1
This has the advantage of being able to capture both still images and continuous images using one image sensor.

Furthermore, according to the present invention, the storage capacity in the charge storage section is increased in accordance with the amount of charge transferred from a plurality of corresponding photoelectric conversion sections, so the signal charge amount is fully utilized and the S/N ratio is reduced. This has the effect of allowing charges to be accumulated in a plurality of photoelectric conversion units without any trouble.

By adding and accumulating the charges of multiple photoelectric conversion units, the relative proportion of noise decreases, so the S/N -
The ratio is improved and high quality images can be obtained.

Incidentally, in the embodiment of the present invention, the charges of two photoelectric conversion units are simply added, but they may be weighted and added. Further, operations other than addition may be performed.

It goes without saying that the number of photoelectric conversion sections to be combined may be limited to two.

As explained above, by using the solid-state image sensor structure according to the present invention, it is possible to support both high-quality still image shooting consisting of one non-interlaced frame output and general video shooting consisting of two interlaced field outputs. Has a revolutionary effect 0

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of an embodiment of the present invention, FIG. 2 is a schematic diagram showing a configuration example of the embodiment of the present invention, FIG. 3 is a schematic diagram of internal potential of the embodiment of the present invention, and FIG. a) + (b
1 is a diagram showing an example of a sequence when the present invention is used for still image and video shooting, (al is a sequence diagram for still image shooting, and (b) is a 7-Kejis diagram for video shooting.
is the imaging section, 3 is the storage section, 5 is the horizontal transfer register 0 28 Procedural amendment (method) February 12, 1980 Commissioner of the Japan Patent Office Shima 1) Haruki Tono 1, Indication of the case 1982 Patent Application No. 146585 2. Name of the invention Frame transfer type i-image element 3, Relationship with the amended person's case Patent application masterpiece Place 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100) Canon Co., Ltd. Representative Ryu Kaku Sanbu 4, Agent location fi 146 3-30-2 Shimomaruko, Ota-ku, Tokyo
5. Date of amendment order: January 26, 1980 (shipment date) 6. Specification subject to amendment (full text) 1. Engraving of the amended specification (no change in content)

Claims (1)

[Claims] A storage section is provided that forms an image signal for one pixel by combining and storing the charges of a plurality of photoelectric conversion sections, and the capacity of this storage section is increased in accordance with the amount of charges to be combined. Frame transfer type photography f
l element.