JPH05236355A - Driving method for solid-state image-pickup device - Google Patents

Abstract

PURPOSE:To provide a driving method for a solid-state image-pickup device which can reed the partial image information out of a screen at a high speed without adding and special structure. CONSTITUTION:A driving method of a solid-state image-pickup device includes the photoelectric transducers (Pij) arranged in a matrix form and connected to the vertical charge transfer paths (VCCD) arranged in the column direction via the transfer gates (Tg) and a horizontal charge-transfer paths (HCCD) connected to one of both ends of each path (VCCD). In such a constitution, a process (t=0) is provided to apply a field shift signal to a transfer gate and to shift the stored charge of the transducers (Pij) to the paths (VCCD) together with a process (H1) where the charge-transfer signals are applied to the paths (VCCD) even in a horizontal-scanning period and the stored charge of the unnecessary parts are sequentially to the path (HCCD), a process where the stored charge of the necessary parts are transferred to the path (HCCD) by an amount equal to a prescribed number of rows in a horizontal blanking period after the path (HCCD) is cleared (H2), and the processes (H3, H4, H5) where the transfer of charge is stopped to the path (HCCD) from the paths (VCCD) in a horizontal scanning period and the charge of the necessary parts of the path (HCCD) are transferred.

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 more particularly to a solid-state image pickup device including a large number of photoelectric conversion elements.

[0002]

2. Description of the Related Art In an interline type solid-state image pickup device, photoelectric conversion elements are arranged in rows and columns, vertical charge transfer paths are arranged in proximity to respective columns of the photoelectric conversion elements, and one end of the vertical charge transfer path is horizontally aligned. The charge transfer path is connected.

Further, in the FIT type solid-state image pickup device,
A light receiving section having a photoelectric conversion function and a storage section having no photoelectric conversion function are continuously formed to form a vertical charge transfer path, and a horizontal charge transfer path is connected to one end of the charge transfer path of the storage section. It In such a two-dimensional solid-state imaging device, the demand for high resolution increases the number of pixels.

Further, adjustment of automatic exposure / automatic focus (AE / AF) and the like can be performed using the output signal of the solid-state image pickup device. At the time of adjustment, if the image signal of a part of the screen is obtained, adjustment such as AE / AF can be performed.

For example, when the main subject exists in the center of the screen, adjustment can be performed if the image signal of the center of the screen is obtained. The image signals of the other parts are unnecessary for performing the adjustment once.

When obtaining image information of the central portion of the screen for adjustment of AE / AF and the like, in the conventional solid-state image pickup device, the image signal of the entire screen is read out and then the image information of the necessary portion is obtained. .. However, particularly in a multi-pixel solid-state imaging device, it may take too much time to read out information of a necessary portion such as a screen central portion.

In order to solve this point, there has been proposed a solid-state image pickup device having a special structure for selectively reading out image information of only a necessary portion on the screen. In the solid-state imaging device having such a structure, it is possible to selectively read out image information of an arbitrary portion, but the photoelectric conversion time becomes short, and it may be difficult to obtain information of a subject with low illuminance. ..

[0008]

As described above, in the conventional solid-state image pickup device, it was not easy to read only part of the image information in the screen at high speed. Although there is a solid-state imaging device provided with a special mechanism for reading out image information of a part of the screen, it has not always been possible to obtain satisfactory performance.

An object of the present invention is to provide a method for driving a solid-state image pickup device capable of reading out a part of image information in a screen at high speed without adding a special structure.

[0010]

According to a method of driving a solid-state image pickup device of the present invention, photoelectric conversion elements arranged in rows and columns are coupled to vertical charge transfer paths arranged in a column direction via transfer gates to vertically A method of driving a solid-state imaging device, wherein a horizontal charge transfer path is connected to one end of a charge transfer path, the method comprising applying a field shift signal to a transfer gate to shift the accumulated charge of a photoelectric conversion element to a vertical charge transfer path. , A step of applying a charge transfer signal to the vertical charge transfer path even during the horizontal scanning period to transfer the accumulated charges in unnecessary portions to the horizontal charge transfer path one after another, and during the horizontal blanking period after clearing the horizontal charge transfer path. The process of transferring the accumulated charges in the necessary portion to the horizontal charge transfer path for a predetermined row, and stopping the charge transfer from the vertical charge transfer path to the horizontal charge transfer path during the horizontal scanning period, And a step of performing a load transfer.

[0011]

In the adjustment of AE / AF and the like, it suffices to obtain image information of a part of the screen such as the center of the screen. In normal charge reading, the image information for each row is transferred to the horizontal charge transfer path, and the image information for the next one row is transferred to the horizontal charge transfer path after transferring horizontally in the horizontal charge transfer path. Was.

If charges are transferred from the vertical charge transfer path to the horizontal charge transfer path even during the horizontal scanning period in which the horizontal charge transfer path is operated, the transfer speed in the vertical charge transfer path is significantly increased. According to such a transfer method, charge mixing occurs in the horizontal charge transfer path, but no problem occurs in the case of charge signals in a portion that is not originally required.

For example, when there is required image information in the center of the screen, the signal charges in the unnecessary portions above and below the screen are transferred at high speed while causing charge mixing, and are swept away from the horizontal charge transfer path. By transferring the necessary image information in the central portion according to the normal charge transfer method, the image signal required for adjustment can be obtained at high speed.

When it is desired to obtain image information of a screen with low illuminance, it is possible to transfer the image information of a necessary portion to the horizontal charge transfer path at a time for a plurality of lines to obtain amplified image information.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIG.
FIG. 1A is a plan view schematically showing a planar configuration of the solid-state imaging device.

In the figure, a large number of photodiodes Pij
Are arranged in a matrix in the imaging region. Adjacent to each column of the photodiode matrix, a vertical charge transfer path VCCD
And a transfer gate Tg for carrying out charge transfer is formed between the adjacent photodiodes. A horizontal charge transfer path HCCD is connected to one end of the vertical charge transfer path VCCD arranged in each column.

In a normal image pickup apparatus, after the accumulated charge of each photodiode Pij is cleared, an image is irradiated on the light receiving surface, and each photodiode Pij accumulates image information corresponding to the irradiation light intensity.

After the accumulation operation is completed, the transfer gate Tg is triggered to shift the charge accumulated in each photodiode Pij to the vertical charge transfer path VCCD. After that, the charge accumulated in the VCCD is transferred downward in the VCCD and is transferred row by row to the horizontal charge transfer path HCCD, where H
It is transferred horizontally in the CCD. In this way 1
Image information for each line can be obtained. At the time of adjustment for performing AE / AF, it is desired to quickly obtain image information of the center of the screen. The operation of obtaining the image information for three lines in the center of the screen will be described below.

FIG. 1B shows a drive waveform of the solid-state image pickup device when only the image information for three lines in the center of the screen is obtained.
The signal waveform applied to the gate electrode G1 of the vertical charge transfer path is indicated by φ1, and similarly, the gate electrodes G2, G3, G
The signal waveforms applied to 4 are indicated by φ2, φ3, and φ4. Further, the driving signal of the horizontal charge transfer path HCCD is indicated by φH.

In the structure shown in FIG. 1A, two gate electrodes are arranged for each row of photodiodes, and one gate electrode of the VCCD corresponding to two rows of photodiodes constitutes one set to implement four-phase driving.

In this configuration, if image information is read out from all the photodiodes at the same time, one image information per two electrodes is stored in the VCCD.
Phase drive cannot be performed. In this case, HCC
Image information is sequentially read from the side closer to D, and four-phase driving is performed only in the area where the empty packet spreads. When reading one line of two lines or one line of four lines, four-phase driving can be performed as it is.

At the time of adjustment, 4 at time t = 0
A field shift signal is applied to the second gate electrode and the fourth gate electrode of the group of gate electrodes, and the accumulated charges of all the photodiodes Pij are applied to the vertical charge transfer path VCC.
Shifted to D. In the next horizontal blanking period, the image information most sent to the HCCD is transferred to the horizontal charge transfer path HCCD.

Further, in the subsequent horizontal scanning period H1, the vertical charge transfer path VCCD to the horizontal charge transfer path HCC.
The charges are transferred to D one after another. For this reason, charge mixing occurs in the horizontal charge transfer path HCCD, but no problem occurs because the image information in this portion is not used for adjustment such as AE / AF. In this way, by the end of the first horizontal scanning period H1, all the image information of the unnecessary portion in the first half is transferred to the horizontal charge transfer path HCCD.

In the next horizontal scanning period H2, the charge transfer of the vertical charge transfer path VCCD is stopped, and only the charge transfer of the horizontal charge transfer path HCCD is performed. In this way, the horizontal charge transfer path HCCD is cleared. Since the charges read up to this point are unnecessary charges, they are swept away by an appropriate means.

In the second horizontal scanning period H2, after clearing the horizontal charge transfer path HCCD, in the next horizontal blanking period, the image signal of the necessary first row is transferred from the vertical charge transfer path VCCD to the horizontal charge transfer path VCCD. Transfer to HCCD.

In the subsequent horizontal scanning period H3, the charge signal transferred to the horizontal charge transfer path HCCD is transferred in the horizontal direction. Similarly, the image information of the required portion is transferred line by line from the vertical charge transfer path VCCD to the horizontal charge transfer path HCCD during the horizontal blanking period, and horizontally in the horizontal charge transfer path HCCD during the subsequent horizontal scanning period. , Get the required image information.

When the required image information is the image information for the three lines in the central portion, the image information for the three lines is read in this way. After that, the remaining unnecessary charges remaining on the vertical charge transfer paths are sequentially supplied to the vertical charge transfer paths VC during the horizontal scanning period.
The data is transferred from the CD to the horizontal charge transfer path HCCD, and is read out from the horizontal charge transfer path HCCD, so that it is swept away at high speed.

According to such a driving method, the unnecessary charge sweep-off can be performed once within two horizontal scanning periods,
In addition to the time required to read out the image information of a required portion for reading one screen of image information, a total of four horizontal scanning periods are required, two times before and after, two horizontal scanning periods each.

The case where the image information of the required portion is read line by line has been described. However, when the illuminance of the image information of the required portion is low, the image information of the required portion is grouped by a plurality of lines and the horizontal blanking period is performed. It is also possible to read from the vertical charge transfer path VCCD to the horizontal charge transfer path HCCD.

For example, instead of the drive waveform shown in FIG. 1B, in the horizontal blanking period after the horizontal scanning period H2, the image information of a plurality of rows are continuously input to the vertical charge transfer path VCCD.
To the horizontal charge transfer path HCCD, and the amplified image information is stored in the horizontal charge transfer path HCCD.

In the next horizontal scanning period H3, by driving the horizontal charge transfer path HCCD, amplified image information can be obtained. By repeating the same scanning a required number of times, the amplified image information can be obtained for a plurality of lines. Of course, in this case, the necessary portion at the center of the screen is not the three rows, but the number of rows to be read simultaneously × the number of times of reading.

Further, the case where the image information in the central portion of the screen is read has been described, but the image information to be read need not be only in the central portion of the screen. For example, when there is a main subject at the lower part of the screen, the upper part of the screen, etc., only the image information of the relevant part can be read out. It is also possible to set a plurality of areas on the screen and read out the image information of those areas.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to these. For example,
Similar to the interline type solid-state image pickup device, the same drive system can be adopted in the FIT solid-state image pickup device. It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like can be made.

[0034]

As described above, according to the present invention,
At the time of adjustment such as AE / AF, only necessary image information is read as a signal, and unnecessary image information is swept away at high speed, so that necessary information can be read out at high speed.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an example of the present invention. FIG. 1A is a plan view schematically showing a planar configuration of the solid-state imaging device, and FIG. 1B is a graph showing a drive waveform of the solid-state imaging device.

[Explanation of symbols]

 Pij photodiode Tg transfer gate VCDD vertical charge transfer path HCCD horizontal charge transfer path

Claims (3)

[Claims] 1. A solid state in which photoelectric conversion elements arranged in a matrix are coupled to vertical charge transfer paths arranged in a column direction via transfer gates, and a horizontal charge transfer path is connected to one end of the vertical charge transfer path. A method of driving an image pickup device, which comprises a step of applying a field shift signal to a transfer gate to shift accumulated charges of a photoelectric conversion element to a vertical charge transfer path, and a step of applying a charge transfer signal to the vertical charge transfer path even during a horizontal scanning period. Applying and transferring the accumulated charge of unnecessary parts to the horizontal charge transfer path one after another, and after clearing the horizontal charge transfer path, the accumulated charge of the necessary part is transferred to the horizontal charge transfer path for a predetermined row during the horizontal blanking period. And a step of stopping the charge transfer from the vertical charge transfer path to the horizontal charge transfer path during the horizontal scanning period and performing the charge transfer of a necessary portion of the horizontal charge transfer path. Law. 2. A charge transfer signal is applied to the vertical charge transfer paths even after the necessary charges are transferred to the vertical charge transfer paths, so that the remaining charges of the unnecessary parts are transferred to the horizontal charge transfer paths. The method for driving a solid-state imaging device according to claim 1, further comprising a step of performing transfer to a transfer path. 3. The method of driving a solid-state image pickup device according to claim 1, wherein the charges accumulated in a necessary portion during the horizontal blanking period are transferred at once for a plurality of rows.