JPH0383464A - Driving method for solid-state image pickup device - Google Patents

Abstract

PURPOSE:To prevent noise from being generated during signal processing by sweeping out an unnecessary charge in a vertical transfer part from an accumulation part into a semiconductor substrate and afterwards, starting transfer in the accumulation part earlier than the vertical transfer part by several steps. CONSTITUTION:During a video scanning period B1, a vertical transfer pulse J1 is impressed to an accumulation part 43 for each horizontal scanning period K1 and the charge is transferred to a horizontal transfer part 44 for each horizontal scanning period K1. Simultaneously with this transfer, the horizontal transfer pulse of a frequency to once transfer the signal charge on the horizontal transfer part 44 during one horizontal scanning period K1, namely, during the vertical transfer pulse J1 is impressed to the horizontal transfer part 44 and the signal charge is outputted from a signal charge detection part 45. From the start of a vertical flyback erasing period A1 to the impression of a charge pulse D1, a vertical high-speed transfer pulse H1 is impressed to a vertical transfer pulse 42 and the unnecessary charge on the vertical transfer part 42 is swept out from the accumulation part 43. Thus, since for the high-speed transfer pulse to be impressed to the vertical transfer part and accumulation part just after it is stopped to impress a voltage for sweeping out the unnecessary charge to the accumulation part, time difference is generated between a charge for video signal and the unnecessary charge by moving the accumulation part earlier by the several steps and the noise generation caused by signal processing is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for driving a solid-state imaging device.

Conventional technology FIG. 4 shows the configuration of a conventional solid-state imaging device.

The solid-state imaging device includes a photoelectric conversion section 41. Vertical transfer section 42° accumulation section 43. Horizontal transfer section 44. It consists of a signal charge detection section 45. The arrow indicates the direction of normal signal charge transfer.

FIG. 1 is a typical example of a driving pulse for a solid-state imaging device having a storage section. In Fig. 1, a is a compound blanking signal, and b is a vertical transfer pulse (hereinafter φVAI) of the VA1 gate among the four-phase clocks applied to the vertical transfer section during normal imaging.
C is the vertical transfer pulse of the vB1 gate (hereinafter φVB) of the four-phase clock applied to the storage section during normal imaging.
(abbreviated as I), d is φvA1 applied when capturing an image so that a part of the screen is enlarged vertically and horizontally by 2 times (area ratio 4 times) (hereinafter referred to as electronic zoom), and e is φVBI applied during electronic zoom imaging. FIG.

FIG. 3 shows the C1 period of FIG. 1 extended in the time axis direction, where b is normal φvA1, c is normal φVBI,
d is φVAI of electronic zoom, e is φVBI of electronic zoom
It shows.

First, the operation during normal imaging shown in FIGS. Transfer by. Next, the vertical transfer section 42 and the storage section 43 are simultaneously moved by the vertical high-speed transfer pulse E1, and the charge is transferred from the vertical transfer section 42 to the storage section 43 by several stages of the storage section 43.

Next, during the video scanning period B1, 1
The vertical transfer pulse J1 is applied every time, and the charges are transferred to the horizontal transfer unit 44 every horizontal period. At the same time,
A horizontal transfer pulse having a frequency that can transfer one signal charge on the horizontal transfer unit 44 between vertical transfer pulses is transferred to the horizontal transfer unit 44.
, and the signal charge is output from the signal charge detection section 45.

A vertical transfer unit high-speed transfer pulse H1 is applied to the vertical transfer unit 42 from the start of the vertical blanking period A1 until before the charge pulse D1, and unnecessary charges are transferred to the storage unit 43. At the same time, a voltage L1 is applied to the gate of the storage section 43 to sweep out unnecessary charges into the semiconductor substrate.

Further, during electronic zooming, as shown in FIGS. 1d and 3d and 3d and 3d, during the vertical blanking period Al, the photoelectric conversion unit
The charges accumulated in the vertical transfer section 42 are transferred to the vertical transfer section 42 by a charge pulse Di. Next, a high-speed transfer pulse G1 is applied to the vertical transfer section 42 for a number of stitches that is approximately one-fourth of the number of vertical steps,
It is swept out from the storage section 43 into the semiconductor substrate. Thereafter, the high-speed transfer pulse F1 is applied to the vertical transfer section 42 for a number of stitches that is about half the number of vertical steps. At the same time, a high-speed transfer pulse E1 for one screen is applied to the storage section 43, and the signal charge is transferred to the gm section 43. Next, in the subsequent video scanning period B1, a vertical transfer pulse J1 is applied to the storage section 43 once every three horizontal scanning periods at a time approximately in the middle of one horizontal scanning period. At the same time, a horizontal transfer pulse having a frequency that can transfer the signal charge on the horizontal transfer section 44 once between two vertical transfer pulses J1 is applied to the horizontal transfer section 44, and the signal charge is output from the signal charge detection section 35. By this driving, the central part of the screen is stretched for one video scanning period and output. Then, the charges for about one quarter of the number of vertical stages left in the vertical transfer section 42 are transferred to the vertical transfer section 42 at the start of the next vertical blanking period A1.
The high-speed transfer pulse H1 applied to the semiconductor substrate 2 sweeps out the liquid from the storage portion into the semiconductor substrate.

Next, the signal processing circuit performs blanking processing, -horizontal scanning period delay, and averaging processing to interpolate the blank area and display an image that is twice the size of the center of the screen vertically and horizontally on the monitor screen. be able to.

Problems to be Solved by the Invention However, in the above configuration, after the unnecessary charges are swept into the semiconductor substrate, when the application of the voltage for depicting the unnecessary charges to the storage section 43 is stopped, the unnecessary charges cannot be completely swept out and the accumulation section 4
The charge remaining in the drain portion of the video signal 3 becomes accumulated in the storage portion, and during the next high-speed transfer, one horizontal period immediately before the video signal charge becomes unnecessary charge, which becomes a source of noise in the signal processing circuit.

In the present invention, the high-speed transfer pulse applied to the vertical transfer section and the storage section immediately after stopping the application of the voltage for depicting unnecessary charges to the storage section moves the storage section several steps earlier, thereby separating the video signal charge and the unnecessary charge. The present invention provides a method for driving a solid-state imaging device that causes a time difference between the two.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for driving a solid-state imaging device according to the present invention provides a method for driving a solid-state imaging device according to the present invention. From the transfer section N(
N: Positive real number) The transfer is configured to start earlier.

Effect: With this configuration, a time difference occurs between the video signal and unnecessary charges, and noise generation due to signal processing can be suppressed.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 4 shows the configuration of a solid-state imaging device used to realize the driving method of the embodiment of the present invention.

The solid-state imaging device includes a photoelectric conversion section 41. Vertical transfer section 42, storage section 43. Horizontal transfer section 44. This is a frame interline transfer consisting of a signal charge detection section 45.

The operation of the solid-state imaging device configured as described above will be explained.

FIGS. 1 and 2 are examples of driving pulses for the solid-state imaging device in this embodiment. In FIGS. 1 and 2, a is a compound blanking signal, b and d are one of four-phase clocks applied to the vertical transfer section, and are φVA1 in the normal mode and electronic zoom mode, respectively. C and e are one of the four-phase clocks applied to the storage section, and indicate φVBI in the normal mode and in the electronic zoom mode, respectively.

First, the operation in the normal mode will be explained with reference to FIGS. 1 and 2. During the vertical blanking period A1, the accumulated charge is transferred from the photoelectric conversion section 41 to the vertical transfer section 42 using a charge pulse D1. Next, charges are transferred from the vertical transfer section 42 to the storage section 43 by the number of stages of the storage section using the vertical high-speed transfer pulse E1. At this time, the storage section 4
Move 3 three steps faster. In other words, the number of high-speed transfer stages of the storage section 43 is (the number of stages of the storage section)+3 stages. Next, during the video scanning period B1, a vertical transfer pulse J1 is applied to the storage section 43 every horizontal scanning period, and the charges are transferred to the horizontal transfer section 44 every horizontal scanning period Kl. At the same time, a horizontal transfer pulse having a frequency that can transfer the signal charge on the horizontal transfer section 44 once per horizontal scanning period, that is, during the vertical transfer pulse J1, is applied to the horizontal transfer section 44, and the signal charge is detected. It is output from the section 45.

Further, from the start of the vertical blanking period A1 until before the charge pulse D1 is applied, a vertical high speed transfer pulse H1 is applied to the vertical transfer section 42, and unnecessary charges on the vertical transfer section 42 are swept out from the storage section 43. do.

Next, the operation of the electronic zoom mode will be explained with reference to d and e in FIGS. 1 and 2. Vertical blanking period A
1, the charges accumulated in the charge conversion section 41 are transferred to the vertical transfer section 42 by the charge pulse D1. Next, the vertical high-speed transfer pulse G1 sweeps charges from the storage section 43 into the semiconductor substrate by one-fourth of the entire screen. Next, vertical high-speed transfer pulses Fl and El are applied to the vertical transfer section 42 and the storage section 43.
Apply. At this time, the storage unit 43 is operated three stages earlier than the vertical transfer unit 42, and the vertical high-speed transfer pulse F1 applied to the vertical transfer unit 42 is applied to the storage unit 43 by one-half stage of the entire screen.
The vertical high-speed transfer pulse E1 applied to (the number of stages of the entire screen +
3) Post and transfer. Next, the remaining half in the storage section 43
In the following video period B1, the charge for the stage is transferred to the storage section 43 by a vertical transfer pulse J1 at a time approximately in the middle of 1 in the horizontal scanning period.
is applied every three horizontal scanning periods. At the same time, a horizontal transfer pulse having a frequency that can transfer the signal charge on the horizontal transfer section 44 once between two vertical transfer pulses J1 is applied to the horizontal transfer section 44, and the signal charge is output from the signal charge detection section 45. Then, at the end of the video scanning period Bl, the signal charges accumulated in about a quarter stage of the photoelectric conversion section 41 on the opposite side from the accumulation section 43 remain in a part of the vertical transfer section 42. This unnecessary signal charge is removed by the vertical high speed transfer pulse H1 of the vertical transfer section 42 at the start of the next vertical blanking period A1.
It is swept out from the storage section 43 into the semiconductor substrate.

In this embodiment, the storage section is moved three stages earlier than the vertical transfer section, but the number of preceding stages is arbitrary.

Effects of the Invention According to the method for driving a solid-state imaging device of the present invention, after unnecessary charges in the vertical transfer section are swept out from the storage section into the semiconductor substrate, the storage section starts transferring several steps earlier than the vertical transfer section. This creates a time difference between the video signal and unnecessary charges, and no noise is generated during signal processing. Therefore, its practical effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is a pulse waveform diagram for explaining the driving method of the solid-state imaging device of the present invention, and FIG. 2 is a pulse waveform diagram for explaining the driving method of the solid-state imaging device of the present invention. 3 is an enlarged view of the portion 01 in FIG. 1 showing pulses for explaining a conventional driving method of a solid-state imaging device, and FIG. 4 shows the countries in which the solid-state imaging device is constructed. A1... Vertical blanking period, B1...
Video scanning period, Dl...Charge pulse, El
, Fl, Gl. Hl... Vertical high speed transfer pulse, Jl...
・Vertical transfer pulse, K1...Horizontal scanning period, 4
1...Photoelectric conversion unit, 42...Vertical transfer unit, 43...Storage unit, 44...Horizontal transfer unit, 45... Signal charge detection section.

Claims (1)

[Claims] A photoelectric conversion section in which a plurality of photoelectric conversion elements are two-dimensionally arranged, a vertical transfer section that vertically transfers signal charges accumulated in the photoelectric conversion section, and signals of a plurality of horizontal lines transferred from the vertical transfer section. an accumulation section that accumulates charges; a horizontal transfer section that horizontally transfers signal charges for one horizontal line transferred from the accumulation section; and converts the signal charges from the horizontal transfer section into a signal voltage or signal current and outputs the signal charges. After sweeping out unnecessary signal charges in the vertical transfer section from the storage section into the semiconductor substrate, the storage section is connected to the vertical transfer section by N (N: positive real number) steps. A method for driving a solid-state imaging device characterized by starting transfer early.