JPH02125581A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve the aperture rate and sensitivity by reading out a charge generated in a photodetector section for plural number of times in one field period at a vertical transfer section, adding the charge read by the vertical transfer section at an adder section and transferring the charge to a horizontal transfer section. CONSTITUTION:The transfer of charge from photodetector sections 1a -1l to vertical transfer sections 2a-2c is implemented for plural number of times during exposure period. When the readout is implemented, the charge on the vertical transfer sections 2a-2c is transferred to adder sections 6a-6c. When the exposure is finished, the charge is transferred at a fast speed to readout buffer sections 7a-7c with the same capacity as the adder sections 6a-6c. Then the charge is being read via a horizontal transfer section 3 for each horizontal scanning period. Since the quantity of charge transferred to the vertical transfer sections 2a-2c aside the photodetector sections 1a-1l at each time is small, a small area is enough for the purpose. Thus, the area of the photodetector sections 1A-1l is increased. Then the aperture rate of the CCD is increased and the sensitivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a solid-state image sensor, and more particularly to a solid-state image sensor with improved aperture ratio and sensitivity.

(Background of the invention) Conventional general solid-state image sensor (hereinafter referred to as CCD)
As shown in Fig. 6, an interline CCD (IT
-CCD) and a frame interline COD (FIT-CCD) shown in FIG.

In the IT-CCD, light receiving sections 1a to 1. There are vertical transfer sections 2a to 2C next to N, and the charges accumulated in the light receiving sections 1a to 1-Ω are sequentially shifted within the vertical transfer sections 2a to 2C and transferred to the horizontal transfer section 3. Then, the charges on the horizontal transfer section 3 are shifted horizontally at high speed and read out to the outside.

On the other hand, in the FIT-CCD, vertical transfer sections 2a to
2c and the horizontal transfer section 3, and has memory sections 5a to 5C between the light receiving sections 1a to 1fl to the vertical transfer sections 2a to 2C.
The transferred charges are shifted to the memory sections 5a to 5C at high speed. Then, the data is vertically shifted sequentially from the memory sections 5a to 5C, and read out from the horizontal transfer section 3 via the read amplifier 4.

(Problem to be Solved by the Invention) Both the IT-CCD and FIT-CCD described above have a vertical transfer section next to the light receiving section, but these vertical transfer sections 2a to 2c
It is desirable that the capacitance is the same as the maximum charge storage capacity of the light receiving sections 1a to 1g. This is because the capacitance of the vertical transfer sections 2a to 2C reaches the saturation signal level, so it is desired to make it as large as possible. However, if the vertical transfer sections 2a to 2c with the same capacity are provided next to the light receiving sections 1a to 1g, the light receiving sections 1a to 1g will be relatively
The area of ~1 g becomes smaller, and the aperture ratio becomes smaller.

As a result, there is a problem in that the sensitivity also decreases.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a CCD with excellent aperture ratio and sensitivity;
To realize a CCD capable of photographing a moving image and having an excellent aperture ratio and sensitivity, and a COD having an excellent aperture ratio and sensitivity and capable of realizing an electronic shutter function when photographing a frame of a moving image.

(Means for Solving the Problems) A first invention for solving the above problems includes: a light receiving section that converts incident light into charges; a vertical transfer section that transfers charges from the light receiving section in a vertical direction; An addition section that adds and stores charges from the transfer section, a horizontal transfer section that horizontally transfers the charges from the addition section, and a read amplifier that reads and outputs the charges from the horizontal transfer section, Charges generated in the light receiving section are read out multiple times within one field period by the vertical transfer section, and the charges read out by the vertical transfer section are added on the addition section and then transferred to the horizontal transfer section. It is characterized by:

A second invention that solves the above problem includes a light receiving section that converts incident light into charges, a vertical transfer section that transfers the charges from this light receiving section in the vertical direction, and the charges from this vertical transfer section are added together. a buffer section that temporarily stores the charge from this addition section; a horizontal transfer section that transfers the charge from this buffer section in the horizontal direction; and a horizontal transfer section that reads out the charge from this horizontal transfer section. and a readout amplifier for outputting, the charges generated in the light receiving section are read out multiple times within one field period by the vertical transfer section, the charges read out by the vertical transfer section are added on the addition section, and then the charges are output to the buffer. While reading from the horizontal transfer section, the light receiving section, vertical transfer section, and addition section perform the next exposure,
It is characterized in that it is configured to perform addition.

A third invention for solving the above problem includes a light receiving section that converts incident light into charges, a vertical transfer section that transfers the charges from this light receiving section in the vertical direction, and the charges from the vertical transfer section being added. A solid-state imaging device comprising: an adding section for accumulating charges in the adding section; a horizontal transfer section for horizontally transferring charges from the adding section; and a readout amplifier for reading out and outputting charges from the horizontal transfer section; The present invention is characterized in that two lines of the vertical transfer section and the addition section are provided for the light receiving section.

(Function) In the first invention, the charges generated in the light receiving section are read out multiple times within one field period in the vertical transfer section, and the charges read out in the vertical transfer section are added on the addition section and then transferred to the horizontal transfer section. Move.

In the second invention, the charges generated in the light receiving section are read out multiple times within one field period by the vertical transfer section, and the charges read out by the vertical transfer section are added on the adding section and then sent to the buffer section. While reading from the horizontal transfer section is being performed, the light receiving section, vertical transfer section, and addition section perform the next exposure and addition.

In the third invention, charges generated in the light receiving section are read out alternately from one of the two series of vertical transfer sections for each field, and are added.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention.

In the figure, reference numerals 1a to 1g are light receiving sections that generate charges according to the amount of received light. Here, a case of 3×4 pixels is shown. Vertical transfer sections 28 to 2c vertically transfer charges generated in the light receiving section.

Reference numeral 3 designates a horizontal transfer unit that horizontally transfers charges from read buffer units 78 to 7c, which will be described later. Reference numeral 4 designates a read amplifier that converts the charges transferred from the horizontal transfer unit 3 into a voltage and reads it out to the outside. . Addition units 6a to 6C add charges transferred multiple times from the vertical transfer unit. This addition section 6
8 to 6c correspond to vertical transfer units 28 to 2c, respectively. Reference numerals 7a to 7c are read buffer sections for storing charges added by the adding section. The read buffer sections 7a to 7c correspond to the addition sections 6a to 6c, respectively. The addition sections 6a to 6c and the read buffer sections 78 to 7c are constructed of large-capacity vertical transfer CCDs.

During the exposure period, from the light receiving units 18 to 1g to the vertical transfer units 2a to 2
Charge transfer to C is performed multiple times. When this reading is performed, the charges on the vertical transfer sections 2a to 2c are transferred to the addition sections 6a to 6c. Therefore, each time multiple reads are performed,
The read charges are added by adding units 6a to 6c. When the exposure is completed, the charges are transferred at high speed to read buffer sections 7a to 7C having the same capacity as adders 6a to 6C. After this,
Charges are read out via the horizontal transfer section 3 in each horizontal scanning period. During this readout period, the light receiving units 1a to IN, the vertical transfer units 2a to 2c, and the adding units 6a to 6C are performing exposure, continuation, and addition of images of the next field.
As soon as reading is completed, the next field can be read.

Therefore, it is possible to handle moving images. If the purpose is only still images, the read buffer units 7a to 7c can be omitted.

Since the amount of charge transferred each time to the vertical transfer sections 2a to 2c next to the light receiving sections 1a to 11 is small, the area thereof can be small. For example, when transferring charges from the light receiving section to the vertical transfer sections 2a to 2c in three parts during the exposure period, the vertical transfer sections 28 to 2c
The charge capacity of 2c is only 1/3 that of the conventional one, and its area is also 1/3.
3 is enough. Therefore, the area of the light receiving sections 1a to 1fI can be increased. Therefore, the aperture ratio of the CCD increases and the sensitivity increases.

FIG. 2 is a block diagram showing the structure of another embodiment.

In this figure, the same parts as in FIG. 1 are given the same numbers. This embodiment differs from FIG. 1 in that two lines of vertical transfer sections and addition sections are provided corresponding to each light receiving section, and that there is no read buffer section.

This CCD is also capable of capturing not only still images but also moving images. That is, while charges are being output from the adding section on one side, charges are being read out from the light receiving section to the other vertical transfer section, and addition is being performed from the vertical transfer section to the adding section.

Then, by performing this operation alternately, a moving image is captured.

For example, in the frame accumulation mode, in an even field, the accumulated charges of the B1 and B2 horizontal scanning lines already stored in the adders 68 to 6C are not read out, and at the same time the light receiving sections (la , le, li, lc,
1g, lk) to the vertical transfer section (2b.

2d, 2f) in a plurality of times, and the adder 68 to
Add in the right column of 6c. Then, in the next odd field, the accumulated charges of the A1 and A2 horizontal scanning lines are added to the adding units 6a to 6a.
At the same time as reading from 6C, the light receiving portions (lb, If) on the B and B2 horizontal scanning lines.

lj, ld, lh, 1ll)) are transferred to the light receiving parts 1a to 1.
The data are read out in multiple batches from the vertical transfer section (2a, 2c, 2e) on the left side of g, and added in the left column of addition sections 6a to 6C.

Note that the first readout of charges from the light receiving sections 13 to 1g in each field also includes charges generated by the incident light in the immediately preceding field period.

This is because one odd/even scanning line is read out alternately for each odd/even field.

Therefore, a frame afterimage occurs. To avoid this, in the first readout from the light-receiving section of each field] a to An operation of discarding to the flow train (OF D) is required. (('') When this operation is performed, the exposure time is reduced and the (fiM level is also lowered.

In the case of field accumulation mode, it will be as shown below. In the odd field, the accumulated charges of A, 4-B, and A2. (Not shown) The charges of + A I and B I + A 2 are read out in multiple batches from the vertical transfer section (2a, 2c, 2e) on the left side of the light receiving section, and added in the left column of addition sections 68 to 6C. .

Then, in the next even field, the adders 6a to 6 have already added
B stored in C. +AI+B + + A At the same time as reading the charge of 2, A and +B.

and A2+B2 are read out in multiple batches from the vertical transfer sections (2b, 2d, 2f) on the right side of the light receiving sections 1a to 1g, and added in the right column of the addition sections 6a to 6C. In this case, no frame afterimage occurs, but a sweep operation is required when a high-speed shutter is required.

In the case of still image shooting operation, the vertical transfer units 2a to 2f are simultaneously driven to perform sweeping, reading, and high-speed transfer.

By performing the addition, it becomes possible to realize an electronic shutter function for frame photography. Even with conventional CCDs, an electronic shutter for frame photography is possible by providing two lines of vertical transfer sections, but this has the drawback of increasing the area of the vertical transfer sections and lowering the aperture ratio and sensitivity. On the other hand, in the CCD of the present invention, the vertical transfer sections 2a to 2 on the sides of the light receiving sections 1a to 1Ω
Since the area of f can be small, even if two lines are provided, the conventional vertical transfer section can achieve an aperture ratio equal to or higher than that of a single line CCD.

Further, if a slight deviation in exposure time is allowed, one series of vertical transfer sections may be provided for each light receiving section. For example, when reading the signals of the scanning lines A, , A2, the adder 6
It is sufficient to alternately move the charges to the left side of the adders 6a to 6C, and transfer the charges to the right side of the adder sections 6a to 6C when the signals of the scanning lines B1 and B2 are read out at L-. In this case, the exposure of one field starts and ends earlier by the high-speed transfer time than the exposure of the other field.

In the case where buffer sections 78 to 7C are added, signals can be read out from the readout buffer sections 7a to 7C even during the frame electronic shutter operation.

Since IDTV and EDTV perform non-ink race scanning, a camera is required to pick up an image in non-ink race mode and read out the resulting signal in an ink-lace manner, but this CCD can handle this.

FIG. 4 is an explanatory diagram showing the potential relationship between the light receiving section 1 and the vertical transfer section 2. In FIG. In the figure, the shaded area is the charge. At the potential (C) in this figure, the light receiving part 1
Charges generated in a to 1g are transferred to vertical transfer sections 2a to 2f. In the present invention, this operation is repeated multiple times in one field. Adjacent electrodes of the vertical transfer sections 2a to 2f alternately take the potentials (A) and (B), so that charges are sent in the vertical direction.

Further, FIG. 5 is an explanatory diagram showing the potential relationship between the vertical transfer section 2 and the addition section 6. The electric charge on the vertical transfer section 2 is transferred to the addition section 6 at the potential shown in (C) in this figure. In the present invention, this operation is repeated multiple times in one field to add charges. Also, (A),
By alternately applying the potential of (B) to the adjacent electrodes of the adders 6a to 6C, the charges in the adders 68 to 6C are sent in the vertical direction. In the case of FIG. 4, the wall between the light receiving section 1 and the vertical transfer section 2 changes according to the potential change of the vertical transfer section 2, and in the case of FIG. The wall changes according to the change in the potential of the adding section 6.

As described above, the charges from the light receiving sections 18 to 1g are read out in multiple times by the small capacity vertical transfer sections 2a to 2c (2a to 2f), and the charges from the vertical transfer sections 2a to 2C (2a to 2f) are read out. are added multiple times by the adders 6a to 6C, and the read buffers 7a to 7c and the horizontal transfer units 3. The data is read out to the outside via a readout amplifier 4. For this reason, the light receiving parts 1a to 1g
The area of the vertical transfer sections 28 to 2c (2a to 2f) adjacent to the vertical transfer sections 28 to 2c (2a to 2f) can be small, and the area of the light receiving sections 13 to 1g can be increased.

Further, after performing the above addition, the added charges are transferred to the readout buffers 7a to 7c to be read out to the outside, and the light receiving units ]a to IL vertical transfer units 2a to 2c (2a
~2f), the addition units 6a to 6c perform the following exposures, which can also be applied to video shooting.

By providing two lines each of the vertical transfer units 2a to 2f and the adders 68 to 6c for the light receiving units 1a to 1g, an electronic shutter function for frame photography of still images can be realized. Furthermore, by adding read buffer units 78 to 7c, frame electronic shuttering of moving images becomes possible.

(Effects of the Invention) As described above in detail, in the present invention, the charges from the light receiving section are read out in multiple steps by the small capacity vertical transfer section, and the charges from the vertical transfer section are added up multiple times by the addition section. Then, it is read out to the outside via a read buffer, a horizontal transfer section, and a read amplifier. Therefore, the area of the vertical transfer section adjacent to the light receiving section can be small, and the area of the light receiving section can be increased. Therefore, a CCD with excellent aperture ratio and sensitivity can be realized.

In addition, after performing the addition, the added charge is transferred to the readout buffer and read out to the outside, and the light receiving section, vertical transfer section, and addition section perform the next exposure, making it possible to shoot a video. COD with excellent aperture ratio and sensitivity can be realized.

By providing two lines each of the vertical transfer section and the addition section for the light receiving section, it is possible to realize a COD in which an electronic shutter function for photographing frames of still images can be realized. Furthermore, by adding a read buffer section, it becomes possible to use a frame electronic shutter for moving images, making it compatible with IDTV and EDTV.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an embodiment of the present invention;
The figure is a block diagram showing the structure of another embodiment of the present invention, FIG. 3 is a block diagram showing the structure of still another embodiment of the present invention, and FIGS. 4 and 5 show the potential of the solid-state image sensor. Explanatory diagram,
Figure 6 is a configuration diagram showing the configuration of IT-CCD, Figure 7 is F
FIG. 2 is a configuration diagram showing the configuration of an IT-CCD. 1a to 1g... Light receiving section 2a to 2f... Vertical transfer section 3... Horizontal transfer section 4... Readout amplifier 6
a to 6C... Addition section 7a to 7C... Readout pamphlet 7 cylinder figures 60 to 6C; Kaho 70 to 7C, readout pamphlet section Fig. 2 6a-, 6cH Addition section Fig. 3 60 to 6C; Adding units 70 to 7c, continuous output buffer angle ξ4 Figures (A) (B) (C) Figure 5 (A) (B) (C) Corner 6 Figures 10 to 11; Vertical transfer of light receiving units 20 to 2C Part angle, etc. 7 Figures 1o to 11; Light receiving parts 20 to 2c, vertical transfer parts 5Q to 5C, memory part

Claims (3)

[Claims] (1) A light receiving section that converts incident light into electric charge, a vertical transfer section that transfers the charge from this light receiving section in the vertical direction, an adding section that adds and accumulates the charges from this vertical transfer section, and this addition. a horizontal transfer section that horizontally transfers charges from the light receiving section; and a readout amplifier that reads and outputs the charges from the horizontal transfer section, and transfers the charges generated in the light receiving section to the vertical transfer section within one field period. 2. A solid-state image pickup device, characterized in that the charges are read out a plurality of times in the vertical transfer section, the charges read out in the vertical transfer section are added on the addition section, and then transferred to the horizontal transfer section. (2) A light receiving section that converts incident light into charge; a vertical transfer section that vertically transfers the charges from this light receiving section; an adding section that adds and accumulates the charges from this vertical transfer section; and this addition. a buffer section that temporarily stores charges from the buffer section; a horizontal transfer section that horizontally transfers the charges from the buffer section; and a readout amplifier that reads and outputs the charges from the horizontal transfer section; Charges generated in the light receiving section are read out multiple times within one field period by the vertical transfer section, and the charges read out by the vertical transfer section are added up on the addition section and then sent to the buffer section. Reading is performed sequentially via the horizontal transfer section, and while reading from the horizontal transfer section described above is being performed, the light receiving section, vertical transfer section, and addition section perform the next exposure,
A solid-state imaging device characterized by being configured to perform addition. (3) a light receiving section that converts incident light into electric charges; The charge from this photodetector is transferred vertically. vertical transfer section, Charges from this vertical transfer section are added and accumulated. an addition section for The charge from this adder is transferred horizontally. horizontal transfer section, Read and output the charge from this horizontal transfer section A solid-state image sensor comprising a readout amplifier, The vertical transfer section and the addition section are used as a light receiving section. A solid-state image sensor characterized in that two lines are provided for each line.