JPS60137174A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To simplify constitution and suppress a smear by driving vertical transfer parts and storage areas in common all the time. CONSTITUTION:A charge which is converted photoelectrically by and stored in a photoelectric converting element 3 is read to a vertical transfer part 5 by a readout gate part 4, which is applied with a transfer pulse phiTG to transfer the signal charge from the photoelectric converting element part 3 to the vertical transfer part 5 and then transfer it to a storage part 6. Simultaneously, the charge of a smear component remaining at the storage part 6 is swept out of a horizontal transfer part 7. The smear is therefore improved according to the transfer speed.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a solid-state imaging device using a charge transfer element.

In particular, the present invention relates to a method for improving interline transfer type smear and easily driving a solid-state image sensor.

[Description of prior art]

Since the interline transfer type charge transfer device has a photoelectric conversion element section and a vertical transfer section adjacent to each other, a smear phenomenon occurs, which is one of the major problems in improving this type of device. Conventionally, to improve this smear phenomenon, for example, as shown in FIG. A structure has been proposed that includes an accumulation section 6 for accumulating , a horizontal transfer section 7 , a smear drain drain 1 , and an overflow control gate 2 .

The driving method for the charge transfer element having this structure is to first sweep out the charge of the smear component generated in the vertical transfer section 5 in the previous field during the vertical blanking period through the overflow control gate 2 to the smear drain 1 at high speed. At this time, the drive pulses δΦ■, -Φv4 of the vertical transfer unit 5 are in a mode for transferring from the bottom to the top in the figure.

Next, the readout gate section 4 is opened in the vertical transfer section 5 from which the smear component has been swept out, and the charges accumulated in the previous field are read out in the light weight and conversion element section 3, and then the charges in the vertical transfer section 5 are read out at high speed. The data is transferred to the storage unit 6. At this time, the drive pulses Φv1 to Φ■4 of the vertical transfer section 5 are in a mode in which the data is transferred from the top to the bottom in the figure, contrary to the above-mentioned sweep operation.

The signal charges accumulated in the accumulation section 6 in this manner are sent to the horizontal transfer section 7 every horizontal scanning period and output at the rate of a standard television signal.

In the structure shown in FIG. 1, since the driving of the vertical transfer section 5 and the storage section 6 are different, the routing of the pass line becomes complicated due to the increase in the number of electrodes, the number of package pins increases, and the area adjacent to the vertical transfer section 5 becomes Furthermore, since the vertical register 5 sweeps out smear in the opposite direction to the standard transfer direction, when the light source is imaged, the amount of remaining smear after improvement by the light source differs between the top and bottom of the screen. There was a drawback.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for driving a solid-state imaging device, which improves these drawbacks, facilitates vertical transfer driving, and has a simplified element structure.

[Features of the invention]

The present invention includes an imaging area including a photoelectric conversion element section, a vertical transfer section using a charge transfer element, a readout gate section, and an accumulation area using a charge transfer element having the same or more number of transfer stages as the vertical transfer section. The solid-state imaging device is characterized in that it includes circuit means for applying a common drive signal to a charge transfer element in the imaging region and a charge transfer element in the storage region, thereby making it possible to suppress smear.

[Explanation based on examples]

Next, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram showing a driving method according to an embodiment of the present invention, and FIG. 6 is a driving timing chart of a device according to an embodiment of the present invention. As shown in FIG. 2, the embodiment of the present invention includes a photoelectric conversion element section 3, a vertical transfer section 5, a readout section 4 for transferring charges photoelectrically converted and accumulated in the photoelectric conversion element section 3 to the vertical transfer section 5;
an accumulation section 6 that accumulates charges transferred from the vertical transfer section 5;
and a horizontal transfer section that receives and outputs charges from the storage section 6. Compared to the conventional example shown in FIG. 1, the present invention is characterized in that the smear drain 1 and the overflow control gate 2, the direct transfer section 5 and the storage section 6 are driven by a common signal.

FIG. 5 shows a timing chart of driving.
During the period 1, the charges in the vertical transfer section 5 and the storage section 6 are sequentially transferred every horizontal scanning period, and are transferred to the horizontal transfer section 7! l
l Output at standard television rate. Time T,
In this case, all the signal charges imaged in the previous field are output, and the vertical transfer section 5 and storage section 6 accumulate charges only for the smear component at the standard transfer rate.

Next, in the period t2, the vertical transfer section 5 and storage section 6 are operated at high speed, and the smear components are swept out through the horizontal transfer section 7. Therefore, at this time T2, the smear component is reduced by high-speed transfer in at least all the transfer means of the vertical transfer section 5.

Here, a transfer pulse ΦTG is applied to the readout gate section 4 to transfer the signal charge of the photoelectric conversion element section 3 to the vertical transfer section 5, and then during a period t, the charges of the vertical transfer section 5 are transferred to the storage section 6.
At the same time, the charge of the smear component remaining in the storage section 6 is swept out from the horizontal transfer section 7, and at t5, standard transfer of the next field is performed in the same manner as tl and tl. It turns out. Therefore, smear is improved according to the transfer speed. In this drive, since the smear is swept out through the horizontal transfer section 7, the smear sweeping drain 1 and the overflow control foot 2 are not required, making the structure simple. When sweeping out through the horizontal transfer unit 7, the vertical transfer unit 5 operates at high speed, so the horizontal transfer unit 7 receives N loads from the vertical transfer unit 5 more times than in normal standard transfer, so the smear component is When the amount of charge is large, the horizontal transfer section 7 will cause pluming.

Such a drawback is that the number of stages of the storage section 6 is limited to the vertical transfer section.

This problem can be solved by creating a structure with more than 5 stages so that the period in which blooming occurs does not intersect with the video signal period. At this time, the number of stages required for the storage section 6 is determined depending on the amount of smear of the element.

In addition, the drive is common to the vertical transfer section 5 and the storage section 6 at all timings, and the voltage is also the same at all timings.

The number of poles is exactly the same as that of conventional interline charge transfer devices, so the package can also be shared, and since transfer is performed in the same direction and with the same clock the same number of times, adjacent parts of the vertical transfer section that occur when transfer is performed in the opposite direction No shading occurs.

〔Effect of the invention〕

As described above, the present invention has the excellent effect of significantly suppressing smear with a simple configuration by driving the vertical transfer section and the storage region in common at all timings.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional driving method having a smear drain structure. FIG. 2 is a block diagram showing a driving method according to an embodiment of the present invention. Figure $3 is a drive timing chart of the device according to the present invention. DESCRIPTION OF SYMBOLS 1... Smear sweeping drain, 2... Overflow control gate, 3... Photoelectric conversion element part, 4
...Reading gate, 5...Vertical transfer section, 6...
Storage section, 7--Horizontal transfer section. Patent Applicant NEC Corporation Agent Patent Attorney Nao Ide Takashi φ■1 兇 1 Fig. φv2 φTG 32 Fig. 3 ro

Claims (1)

[Claims] (1) Completely equipped with an imaging region including a photoelectric conversion element section, a vertical transfer section using a charge transfer device, a readout gate section, and an accumulation region using a charge transfer device having the same or more number of transfer stages as the vertical transfer section. What is claimed is: 1. A solid-state imaging device comprising circuit means for applying a common drive signal to a charge transfer element in the imaging area and a charge transfer element in the storage area.