JPH02194780A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To perform an electronic shutter operation without generating a false signal to be the cause of color shading by sweeping out previously unnecessary electric charge existing in the vertical transfer part of the image pickup part to a swept drain part by using a horizontal flyback line period or a vertical flyback line period. CONSTITUTION:Before the unnecessary electric charge of the vertical transfer CCD 4 of the image pickup part 1 is swept out to the swept drain part 8 at the time of the start of exposure, a CCD drive control part 9 outputs a sweep transfer pulse to the vertical transfer CCD 4 of the image pickup part 1 by using the horizontal flyback line period or the vertical flyback line period, and transfers and sweeps out the unnecessary electric charge in the vertical transfer CCD 4 to the swept drain part 8. Accordingly, before the unnecessary electric charge is transferred from a photoelectric converting part 3 to the vertical transfer CCD 4, the unnecessary electric charge in the vertical CCD 4 can be sufficiently discharged. Thus, even if the electronic shutter operation is performed, the generation of the false signal to be the caused of the color shading can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a solid-state imaging device using a solid-state carrier image.

(Prior art) Conventionally, a frame interline transfer type COD image carrier (
The FIT CCD (hereinafter referred to as FIT CCD) is equipped with a means to change the timing of reading out the signal charge accumulated in the pupil image element, thereby increasing the exposure time of the image reproduced in one field of a television receiver from the usual 1/60 second. The length is also shortened to enable electronic shutter operation.

FIG. 5 is a diagram showing an example of the configuration of a conventional FIT CCD. 1 is the imaging section, 2 is the storage section, 3 is the photoelectric conversion section, 4 is the vertical transfer COD of the imaging section 1, and 5 is the vertical transfer CO of the storage section 2.
D, 6 is a horizontal transfer CC017 is an output section, and 8 is a sweep drain section.

FIG. 6 is a signal waveform diagram showing the electronic shutter operation of the FIT CCD. (A) is the composite blanking signal,
(B) shows the transfer pulses (hereinafter referred to as field shift pulses) 11 and 12 that transfer the signal charge of the photoelectric conversion unit 3 to the vertical transfer CCD 4 of the imaging unit 1, and (C) shows the signal of the vertical transfer COD of the image carrier 1. Transfer pulses (hereinafter referred to as imaging section vertical transfer pulses > 14.15) for sequentially transferring charges to the horizontal transfer CCD 6 or the sweep drain section 8, (D) horizontally transfer the signal charges of the vertical transfer CCD 5 of the storage section 2. A transfer pulse (
(hereinafter referred to as storage unit vertical transfer pulses) 16 and 17, (
E) indicates a pulse (hereinafter referred to as a horizontal transfer pulse) for transferring the signal charge of the horizontal transfer CCD 6 to the output section 7.

Here, the operation of the above conventional example will be explained. First, unnecessary charges photoelectrically converted in the photoelectric converter 2 during the non-exposure period 19 shown in FIG.
Furthermore, this unnecessary charge is transferred to the imaging section vertical transfer pulse 14 (hereinafter referred to as the sweep transfer pulse 14) and the storage section vertical transfer pulse 16 (hereinafter referred to as the sweep transfer pulse 16) that occur during the vertical retrace period. ) to the horizontal transfer CCD 6 or sweep drain section 8.Next, the signal charges photoelectrically converted in the photoelectric conversion section 2 during the exposure period 18 are transferred vertically to the image carrier 1 by the field shift pulse 12 at the end of exposure. The signal charges are transferred to the transfer CCD 4.Furthermore, this signal charge is transmitted to the imaging section vertical transfer pulse 15 and the storage section vertical transfer pulse 17.
The image is transferred from the vertical transfer CCD 4 of the imaging section 1 to the vertical transfer CCD 5 of the storage section 2. In this way, the signal charges transferred to the vertical transfer CCD 5 of the storage section 2 are sequentially transferred to the horizontal transfer CCD 5.
The signal charge is sent to the CD 6, and further read out from the horizontal transfer CCD 6 via the output section 7 by the horizontal transfer pulse shown in FIG. 6(E).

However, in the FIT CCD described above, the photoelectric conversion section 3
In order to intensively transfer and discard unnecessary charges in a short period of time by the sweep transfer pulse 14.16, the vertical transfer C of the image carrier 1 is
Unnecessary charges that could not be transferred remain within the CD4. Therefore, at the end of exposure, the unnecessary charge remaining in the vertical transfer C0D4 is mixed with the signal charge read out from the photoelectric conversion unit 3 by the field shift pulse 12, and this becomes a false signal that causes image quality deterioration. . This false signal causes color shading as shown in FIG. 3, for example. Note that the false signal that appears when a high-brightness subject is photographed and the upper part of the camera monitor screen turns white has already been improved using technology disclosed in Japanese Patent Application Laid-Open No. 62-95077, etc. No improvements have been made to the color shading mentioned above.

(Problems to be Solved by the Invention) As mentioned above, when an electronic shutter operation is performed in a conventional FIT CCD, unnecessary charges that cannot be discarded remain in the vertical transfer CCD 4 of the Wi image section 1. When the signal charges are read out, they are read out together, resulting in a false signal, and this false signal causes color shading, which deteriorates the image quality. SUMMARY OF THE INVENTION In view of the above drawbacks, it is an object of the present invention to provide a solid-state imaging device that can perform an electronic shutter operation without generating false signals that cause color shading.

[Structure of the Invention (Means for Solving the Problems)] The present invention transfers signal charges from a photoelectric conversion section to a vertical transfer section of an imaging section during a vertical retrace period, and further transfers the signal charges to a vertical transfer section of an accumulation section. After transferring the signal charge to the storage section, the signal charge is transferred from the vertical transfer section of the storage section to the horizontal transfer section during the horizontal retrace period,
The solid-state imaging device further performs an operation of sequentially extracting the signal charges from the horizontal transfer section, and also performs an operation of sweeping out unnecessary charges in the vertical transfer section of the imaging section to a sweep drain section at the start of exposure when performing an electronic shutter operation. At the start of the exposure, before the unnecessary charges in the vertical transfer section of the image pickup section are swept out to the sweep drain section, the unnecessary charges in the vertical transfer section of the m image section are removed using the horizontal blanking period or the vertical blanking period. It has a configuration in which a sweeping means is provided to sweep out charges to a sweeping drain section in advance.

(Function) In the solid-state imaging device of the present invention, the sweeping means uses the horizontal blanking period or the vertical blanking period to sweep out unnecessary charges in the vertical transfer sections of the two front imaging sections to the sweep drain section in advance.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings, in which the same parts as those of the conventional example are denoted by the same reference numerals. FIG. 1 is a block diagram showing an embodiment of a FITCCD and its driving circuit to explain the solid-state m-image device of the present invention. 1 is the imaging section, 2 is the storage section, 3 is the photoelectric conversion section, and 4 is the vertical transfer COD of the imaging section 1.
, 5 is the vertical transfer COD of the storage section 2, and 6 is the horizontal transfer COD.
, 7 is the output section, 8 is the sweep drain section, and FIT CC
It constitutes D. 9 is a COD drive control section that generates various pulses to drive this FIT CCD.

FIG. 2 is a generation time chart of various signals and pulses showing the operation of the COD drive control section.

(A) and (B) are composite retrace signals, (C) are field shift pulses 11.12, (D) are imaging unit vertical transfer pulses 13, 14, and 15, and (E) are storage unit vertical transfers. Pulses 16 and 17 are shown, and (F) shows the horizontal transfer pulse. Here, the Wi image section vertical transfer pulses (hereinafter referred to as sweep transfer pulses) 13 and 14 and the storage section vertical transfer pulses (hereinafter referred to as sweep transfer pulses) 16 are shown in the vertical transfer CCDJ shown in FIG. This pulse transfers unnecessary charges to the drain section 8 in the opposite direction to the arrow shown in FIG. On the other hand, the image carrying section vertical transfer pulse 15 and the storage section vertical transfer pulse 17 are pulses that transfer signal charges from the R image section 1 to the storage section 2 in the same direction as the arrow shown in the vertical transfer CCD 4.

Next, the operation of this embodiment will be explained. Near the end of the non-exposure period 19, the CCD drive control unit 9 operates as shown in FIG.
As shown, a sweep transfer pulse 13 is output to the vertical transfer CCD 4 of the image carrier 1, and unnecessary charges in the vertical transfer CCD 4 are transferred to the sweep drain section 8 and swept out. The bond, C
At the start of the exposure period 18, the CD drive control section 9 operates as shown in FIG.
), a field shift pulse 11 is output to the photoelectric conversion unit 3 to transfer unnecessary charges photoelectrically converted during the non-exposure period 19 from the photoelectric conversion unit 3 to the vertical transfer CCD 4 of the image carrier 1. Next, the CCD drive control section 9 operates as shown in FIG.
D) and the sweep transfer pulse 14 as shown in FIG. 2(E).
．． 16 is output to the vertical transfer CCD 4 of the am image section 1 and the vertical transfer CCD 5 of the storage section 2 within the vertical retrace period.
Unnecessary charges in the CD 4 and the vertical transfer CCD 5 are swept out to the sweep drain section 8.

Thereafter, during the exposure period 18, the charges photoelectrically converted in the photoelectric conversion section 3 are transferred to the vertical transfer CCD 4 of the imaging section 1 by a field shift pulse 12 generated from the CCD drive control section 9 as shown in FIG. 2(C). will be forwarded to. Next, the CCD
The drive control section 9 transmits the imaging section vertical transfer pulse 15 and the storage section vertical transfer pulse 1 at the timing shown in FIG. 2 (D>, (E)).
7 to transfer the signal charge from the vertical transfer CCD 4 to the vertical transfer CCD 5, and further transfer this signal charge to the horizontal transfer CCD 6. Thereafter, this signal charge is read out from the horizontal transfer CCD 6 via the output section 7.

However, the above-mentioned sweep transfer pulse 13 is shown in FIG. 2(A).

As shown in (D), it does not fit within the vertical retrace period and extends into the video period. Therefore, as shown in FIG. 2(B), the vertical blanking period is extended by several horizontal scanning periods to correct the above-mentioned problem. However, the width of the vertical retrace period should be such that it does not cover the effective picture frame of a home television receiver.

According to this embodiment, unnecessary charges are swept out from the vertical CCD 4 of the imaging section 1 not only at the start of exposure, but also at the sweep transfer pulse 13 before the unnecessary charges are transferred from the photoelectric conversion section 3 to the vertical transfer CCD 4. Therefore, unnecessary charges in the vertical CCD 4 can be sufficiently discarded.

Therefore, even if an electronic shutter operation is performed, the above-mentioned unnecessary charges will not be mixed in and read out when signal charges are read out, making it possible to prevent the generation of false signals that cause color shading, and to produce high-quality images. Obtainable.

FIG. 3 is a time chart explaining another embodiment of the present invention. (A> is the composite retrace signal, (B) is the field shift pulse 11.12, (C) is the imaging section vertical transfer pulse 14.15, (D) is the storage section vertical transfer pulse 16
．． 17 and (E) respectively show horizontal transfer pulses. Also in this example, unnecessary charges in the vertical transfer CCD of the imaging section are swept out to the sweep drain section using the sweep transfer pulse 14 shown in FIG. 3(C) during the vertical retrace period. This operation is similar to the conventional and previous embodiments. In this example, as shown in FIG. 4, which is an enlarged view of part A in FIG. 3, during the horizontal retrace period 20,
A sweep transfer pulse 21 is generated, this pulse 21 is sent to the vertical transfer COD of the image carrier section, and unnecessary charges in the vertical transfer CCD are swept out to the sweep drain section. As a result, in this embodiment, as in the previous embodiment, unnecessary charges in the vertical transfer CCD can be sufficiently swept out, generation of false signals that cause color shading can be prevented, and electronic shutter operation can be performed. The actual image can be maintained in high quality.

It goes without saying that the same effect can be obtained even if the two embodiments described above are implemented together.

[Effects of the Invention] As described above, according to the solid-state imaging device of the present invention, an electronic shutter operation can be performed without generating false signals that cause color shading.

[Brief explanation of the drawing]

Figure 1 shows an FIT C to which the solid-state imaging device of the present invention is applied.
Block diagram showing one embodiment of a CD and its drive unit, Part 2
The figure is a generation time chart of various signals and pulses that drive the FIT CCD shown in Figure 1, Figure 3 is a time chart explaining another embodiment of the present invention, and Figure 4 is a partially enlarged view of Figure 3. , FIG. 5 is a block diagram showing an example of a conventional FIT CCD, and FIG. 6 is a signal and pulse generation time chart showing the operation of FIG. 5. 1... Wi image section 2... Accumulation section 3...
Photoelectric conversion section 4, 5... Vertical transfer CCD 6...
Horizontal transfer COD 7... Output section 8... Sweeping drain section 9... COD drive control section agent Patent attorney
Noriyuki Ken Yudo Uji HiroshiFigure 4Figure 1Figure 5

Claims (1)

[Claims] After transferring the signal charge from the photoelectric conversion section to the vertical transfer section of the imaging section during the vertical retrace period and further transferring this signal charge to the vertical transfer section of the storage section, the signal charge is transferred to the vertical transfer section of the storage section during the horizontal retrace period. The signal charges are transferred to the horizontal transfer section from the image pickup section, and the signal charges are sequentially taken out from the horizontal transfer section. In addition, when performing an electronic shutter operation, unnecessary charges in the vertical transfer section of the imaging section are removed at the start of exposure. In a solid-state imaging device that performs a sweeping operation to a sweep drain section, a horizontal blanking period or a vertical blanking period is used before sweeping unnecessary charges in a vertical transfer section of the imaging section to a sweep drain section at the start of the exposure. 2. A solid-state imaging device, further comprising a sweeping means for sweeping out unnecessary charges in a vertical transfer section of the imaging section to a sweeping drain section in advance.