JP2002118247A - Solid-state image pick up element and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the amount of dealing charge in a vertical transfer part and simplify picture element structure and circuit constitution in a solid-state image pick up element and its driving method. SOLUTION: This solid-state image pick up element 1 is provided with a sensor 2 where photoelectric transducers are arranged in a matrix type, a vertical transfer 3 which is connected with the sensor and transfers vertically signal charges stored in the sensor, and an electrode 4 connected with the transfer. The number of electrodes in the transfer to one picture element in the sensor is made one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device and a method of driving the same, which increases the amount of charges handled by a vertical transfer section to increase the amount of saturation signals and allows signals of all pixels to be read out independently. Related to technology.

[0002]

2. Description of the Related Art A conventional solid-state image sensor, for example, an interline transfer (IT) type CCD solid-state image sensor (hereinafter abbreviated as IT image sensor) a whose structure is shown in FIG. It has the arranged vertical transfer section c. In general, a four-phase driving method is adopted in which the vertical transfer section c has four-phase gates, and a driving pulse is applied to each of these gates.

The four-phase drive type IT image pickup device a has an advantage that the amount of charge handled by the vertical transfer section is large (two electrodes = charge storage portion / sensor pixel / pixel).
(Parts hatched in FIG. 4). However, the IT imaging element a needs a drive pulse applied to each gate, that is, four different drive pulses V1 to V4 shown in FIG. 5, and thus has a problem that the drive circuit is complicated. Was.

In the case of a so-called Bayer type color filter array, which is often used in a primary color solid-state image pickup device, one frame = two fields shown in FIG.
In the case of the B) configuration, the signal output in each single field is only the R or B line. For this reason, a driving mode for pixel thinning for separately outputting the R and B lines at a time is required in the circuit configuration of the driving circuit, and there is a problem that the driving circuit becomes complicated.

Further, a conventional all-pixel reading type IT imaging device d shown in FIG. 7 has a sensor unit e and a vertical transfer unit f arranged in an interline system. A three-phase drive system having three-phase gates is employed.

[0006] The IT image pickup device d of the above all pixel readout method
As shown in FIG. 8, the drive circuit is driven by three drive pulses V1 to V3 applied to each gate, as compared with the IT image pickup device a which requires the four drive pulses. However, the amount of charge handled by the vertical transfer portion f is small (one electrode = charge storage portion for 1/3 pixel of sensor / portion shaded in FIG. 7). There was a point. Also,
Since one frame is equal to one field (A), a pixel thinning drive mode is separately required as shown in FIG.
There is a problem that the driving circuit is complicated.

Further, in the conventional IT image pickup device a and the IT image pickup device d of the all-pixel readout method, two or three vertical transfer portions c are required for one pixel of the sensor, so that the electrode structure of the vertical transfer portion c is required. However, there is also a problem that it becomes finer.

[0008]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to increase the amount of electric charges handled by a vertical transfer unit and to simplify a pixel structure and a circuit configuration.

[0009]

In order to solve the above-mentioned problem, the present invention provides a solid-state imaging device in which the number of electrodes of a vertical transfer unit for one pixel of a sensor unit of a solid-state image sensor is one, and a signal charge is read out. One frame employs an n-field (n ≧ 3) configuration and an n-phase drive system.

Therefore, it is possible to increase the amount of electric charges handled by the vertical transfer section.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the solid-state imaging device and the method of driving the same according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows a configuration of a solid-state image pickup device (hereinafter, simply referred to as an image pickup device) 1 according to the present invention.

The image sensor 1 has an interline transfer (IT) having a three-phase drive type vertical transfer CCD as described later.
As shown in the figure, a sensor unit 2 in which photoelectric conversion elements such as photodiodes are arranged in a matrix, and the sensor unit 2 is connected to the sensor unit 2 in an interline manner, and It has a vertical transfer section 3 for transferring the stored signal charges in the vertical direction, and electrode sections 4 individually connected to the vertical transfer CCDs 3a, 3a,... Of the vertical transfer section 3.

The vertical transfer section 3 is controlled by the electrode section 4.
Are applied with read and transfer drive pulses, respectively. The signal charge read out by the application of the driving pulse and stored in the vertical transfer unit 3 is transferred to an image processing circuit (not shown).

The number of electrodes of the vertical transfer CCD 3a per pixel of the sensor unit 2 is one, and the number of electrodes per pixel of the conventional IT image sensor or the sensor of the all pixel IT image sensor shown in FIGS. Has a simplified structure as compared with the number of electrodes of the vertical transfer CCD of 2 or 3.

Therefore, the charge storage portion in the vertical transfer section 3 is equivalent to one electrode = one pixel of the sensor (the hatched portion in FIG. 1), and the amount of charge handled by the vertical transfer section 3 can be increased. It becomes possible.

In general, the saturation signal amount of the CCD solid-state imaging device is determined by a trade-off between the magnitude of the amount of charge handled in the sensor unit and the vertical transfer unit, that is, the area ratio between the sensor unit and the vertical transfer unit.

Therefore, in the image sensor 1, since the amount of electric charges handled by the vertical transfer section 3 can be increased as described above, the area ratio of the sensor section 2 can be increased accordingly. . As a result, in an imaging apparatus such as a video camera to which the present invention is applied, an increase in the saturation signal amount, which has conventionally been a problem, can be expected to increase the dynamic range for light and dark.

As described above, the driving of the image pickup device according to the present invention employs the structure of 1 frame = n fields (n ≧ 3), and the vertical transfer unit is of the n-phase driving system. . The image sensor 1 in the present embodiment uses one frame = 3 fields, and the vertical transfer unit 3 uses a three-phase drive system.

FIG. 2 shows an example of driving pulses (V1 to V3) applied to the gates 4a, 4a,... Of the electrode section 4 to drive the image pickup device 1. That is, the image pickup device 1 can output data of all the pixels by reading out data of 1/3 of all the pixels in each of the fields A, B, and C, and synthesizing these data by a signal processing block (not shown) at the subsequent stage. It has been. When the readout lines are rearranged in the signal processing block, data can be output in a normal interlace mode.

The image pickup device 1 has a structure of one frame = three fields and employs a three-phase drive system in the vertical transfer unit 3. Therefore, only three drive pulses V1 to V3 are used, and a drive circuit (not shown) is used. It is possible to reduce power consumption and simplify the circuit scale. As a result, in an imaging device such as a video camera to which the present invention is applied, it is possible to reduce power consumption and simplify the circuit scale. Also, in an imaging device such as a video camera to which the present invention is applied,
The circuit scale can be simplified.

Further, in the case of a Bayer type color filter array which is often used in a primary color CCD solid-state image pickup device, the configuration of 1 frame = n fields (n ≧ 3) is further limited, and 1 frame = m With the field (odd number of m ≧ 3) configuration, the signal output in each single field includes the R and B lines. FIG. 3 shows an example in which one frame = 3 fields.

That is, in each of the fields A, B and C,
The R and B lines are included alternately, and by repeating this single field drive, it becomes possible to perform pixel thinning drive.

Therefore, in the above-described configuration of 1 frame = m fields (m odd number of m.gtoreq.3), since the R and B lines are already present in the signal output in each field, the pixel thinning drive mode is unnecessary. As a result, the circuit scale of the drive circuit can be simplified. As a result, in an imaging device such as a video camera to which the present invention is applied,
The circuit scale of the drive circuit can be simplified.

By the way, in order to increase the number of pixels of the CCD solid-state imaging device and to reduce the optical size, miniaturization of the manufacturing process of the sensor section and the electrode section is a subject to be solved in the future. In the structure of the CCD solid-state imaging device according to the present invention, the number of electrodes of the vertical transfer unit for one pixel of the sensor is set to two in the conventional art.
Since the number of simplifications is reduced from three to one, it is very advantageous in the manufacturing process of the electrode part.

As described above, in the present invention, the number of electrodes of the vertical transfer unit for one pixel of the sensor is reduced to one, and one frame = n fields (n ≧ 3). It is possible to simultaneously increase the saturation signal amount, reduce the power consumption of the driving circuit, and simplify the driving circuit, which were difficult to realize with the element.

It should be noted that the specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples for embodying the present invention. The scope should not be construed as limiting.

[0028]

As described above, the solid-state imaging device according to the present invention comprises a sensor unit having photoelectric conversion elements arranged in a matrix, and a signal charge connected to the sensor unit and accumulated in the sensor unit. It has a vertical transfer unit for transferring data in the vertical direction and an electrode unit connected to the vertical transfer unit, and the number of electrodes of the vertical transfer unit for one pixel of the sensor unit is one. One pixel of the sensor serves as a charge storage portion, and the amount of charge handled by the vertical transfer portion can be increased.

According to the second aspect of the present invention, one frame is composed of n fields (n.gtoreq.3) and an n-phase driving method is used for reading out signal charges, so that power consumption is reduced and driving is performed. The circuit can be simplified.

The method for driving a solid-state image pickup device according to the present invention comprises: a sensor unit having photoelectric conversion elements arranged in a matrix;
A method for driving a solid-state imaging device, comprising: a vertical transfer unit connected to the sensor unit and vertically transferring a signal charge stored in the sensor unit; and an electrode unit connected to the vertical transfer unit. The number of electrodes of the vertical transfer unit for one pixel of the unit is set to one, and the signal charge is read out.
Since one frame employs the n-field (n ≧ 3) configuration and the n-phase driving method, the number of electrodes of the vertical transfer unit for one pixel of the sensor unit is one, and one electrode, that is, one sensor pixel is used. As a charge storage portion, the amount of charge handled by the vertical transfer section of the solid-state imaging device can be increased, and power consumption can be reduced and the drive circuit can be simplified.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a solid-state imaging device and a driving method thereof according to the present invention together with FIGS. 2 and 3;
It is a figure which shows the structure of D solid-state image sensor schematically.

FIG. 2 is a diagram showing driving pulses.

FIG. 3 is a diagram showing a state of pixel thinning when one frame is composed of three fields.

FIG. 4 shows an example of a conventional CCD solid-state imaging device together with FIGS. 5 and 6, and FIG. 4 schematically shows the structure of the CCD solid-state imaging device.

FIG. 5 is a diagram showing a driving pulse.

FIG. 6 is a diagram illustrating a state of pixel thinning.

FIG. 7 shows an example of a conventional all-pixel readout type CCD solid-state imaging device together with FIGS. 8 and 9; FIG.
FIG. 2 is a diagram schematically illustrating a structure of a CD solid-state imaging device.

FIG. 8 is a diagram showing a drive pulse.

FIG. 9 is a diagram illustrating a state of pixel thinning.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor, 2 ... Sensor part, 3 ... Vertical transfer part,
4 ... Electrode section

Claims (3)

[Claims] A sensor unit in which photoelectric conversion elements are arranged in a matrix; a vertical transfer unit connected to the sensor unit and transferring signal charges accumulated in the sensor unit in a vertical direction; A solid-state imaging device, comprising: an electrode portion connected to the transfer portion; and one electrode of the vertical transfer portion for one pixel of the sensor portion. 2. One frame is read by n for reading signal charges.
The solid-state imaging device according to claim 1, wherein a field (n ≧ 3) configuration and an n-phase driving method are adopted. 3. A sensor unit in which photoelectric conversion elements are arranged in a matrix, a vertical transfer unit connected to the sensor unit and vertically transferring signal charges stored in the sensor unit, and the vertical transfer. A method for driving a solid-state imaging device having an electrode unit connected to a unit, wherein the number of electrodes of a vertical transfer unit for one pixel of a sensor unit is one, and one frame is used for reading signal charges by n fields. (N
≧ 3) A method of driving a solid-state imaging device, which employs a configuration and an n-phase driving method.