JP2578989B2 - Driving method of solid-state imaging device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a driving method of a solid-state imaging device.

2. Description of the Related Art FIG. 4 shows a configuration of a conventional solid-state imaging device. The solid-state imaging device includes a photoelectric conversion unit 41, a vertical transfer unit 42, a storage unit 43, a horizontal transfer unit 44, and a signal charge detection unit 45. Arrows indicate the normal signal charge transfer direction.

FIG. 1 is a typical driving pulse example of a solid-state imaging device having a storage unit. In FIG. 1, a is a composite blanking signal, b is a vertical transfer pulse of the VA1 gate (hereinafter abbreviated as φVA1) of the four-phase clock applied to the vertical transfer unit during normal imaging, and c is a storage unit during normal imaging. Of the four-layer clock applied to the VB1 gate, the vertical transfer pulse of the VB1 gate (hereinafter abbreviated as φVB1), and d represents a part of the screen vertically and horizontally twice (area ratio of 4).
Is a timing chart showing φVA1 and e applied at the time of imaging so that the image is enlarged (to be referred to as electronic zoom) so as to be enlarged (magnification: ×), and φVB1 applied at the time of electronic zoom imaging.

FIG. 3 is an enlarged view of the period C1 in FIG. 1 in the time axis direction, wherein b denotes a normal φVA1, c denotes a normal φVB1, d denotes φVA1 of the electronic zoom, and e denotes φVB1 of the electronic zoom. .

First, the operation at the time of normal imaging in FIGS. 1 b and 3 c and FIGS.
During the vertical blanking period A1, the photoelectric transfer unit 41
The electric charge accumulated in 42 is transferred by the charge pulse D1. Next, the vertical transfer unit 42 and the storage unit 43 are simultaneously moved by the vertical high-speed transfer pulse E1, and charges are transferred from the vertical transfer unit 42 to the storage unit 43 by the number of stages of the storage unit 43. Next, the video scanning period
In B1, a vertical transfer pulse J1 is applied to the storage unit 43 every horizontal period K1, and charges are transferred to the horizontal transfer unit 44 every horizontal period K1. At the same time, the horizontal transfer section 44 between the vertical transfer pulses
A horizontal transfer pulse having a frequency capable of transferring the above signal charge for one time is applied to the horizontal transfer unit 44, and the signal charge is transferred to the signal charge detection unit.
Output from 45.

The vertical transfer unit 42 supplies a vertical transfer unit high-speed transfer pulse H1 from the beginning of the vertical blanking period A1 to the charge pulses D1.
To transfer the unnecessary charges to the storage unit 43. At the same time, the voltage L1 is applied to the gate of the storage unit 43 to sweep out unnecessary charges into the semiconductor substrate.

Also, at the time of electronic zoom, as shown in FIGS. 1d and 3d and FIGS. 3d and 3e, during the vertical blanking period A1, the charge accumulated in the photoelectric conversion unit 41 is transferred to the vertical transfer unit 42 by the charge pulse D1. Forward. Next, a high-speed transfer pulse G1 is applied to the vertical transfer unit 42 by about one-fourth of the number of vertical steps, and the high-speed transfer pulse G1 is discharged from the storage unit 43 into the semiconductor substrate. After that, the high-speed transfer pulse F1 is applied to the vertical transfer unit 42 by about half the number of vertical steps. At the same time, the high-speed transfer pulse E1 for one screen is stored in the storage unit 43.
Is applied to transfer the signal charges to the storage unit 43. Next, in the following video scanning period B1, a vertical transfer pulse J1 is applied to the storage section 43 at a substantially middle time of the horizontal scanning period K1 once in two horizontal scanning periods. At the same time, the horizontal transfer section between two vertical transfer pulses J1
A horizontal transfer pulse having a frequency capable of transferring the signal charges on the one-time transfer is applied to the horizontal transfer unit 44, and the signal charges are output from the signal charge detection unit 35. By this driving, the central portion of the screen is enlarged and output during one video scanning period. The electric charge corresponding to about a quarter of the number of vertical stages remaining in the vertical transfer unit 42 is accumulated by the high-speed transfer pulse H1 applied to the vertical transfer unit 42 at the start of the next vertical blanking period A1. From the part into the semiconductor substrate.

Next, the signal processing circuit performs blanking processing, one horizontal scanning period delay, averaging processing, and interpolates the blank area to display an image in which the center of the screen is enlarged vertically and twice as wide as the entire monitor screen. Can be.

SUMMARY OF THE INVENTION However, in the above-described configuration, the unnecessary charges are swept out into the semiconductor substrate, and then, when the application of the unnecessary charge sweeping voltage to the storage unit 43 is stopped, the unnecessary charges cannot be completely discharged. Part 43
In the next high-speed transfer, the charge remaining in the drain portion becomes unneeded during one horizontal period immediately before the video signal charge, and becomes a noise generation source in the signal processing circuit.

According to the present invention, the high-speed transfer pulse applied to the vertical transfer section and the storage section immediately after the application of the unnecessary charge sweeping voltage to the storage section is stopped, the charge for the video signal and the unnecessary charge are moved by moving the storage section several stages earlier. And 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 problems, a method for driving a solid-state imaging device according to the present invention includes a method of sweeping unnecessary charges in a vertical transfer unit from a storage unit into a semiconductor substrate, and then setting the storage unit in a vertical direction. N from transfer unit
The transfer is started earlier (N: positive real number).

Operation With this configuration, a time difference is generated between the video signal and the unnecessary charges, and generation of noise due to signal processing can be suppressed.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

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

The solid-state imaging device includes a photoelectric conversion unit 41, a vertical transfer unit 42, a storage unit.
This is a frame interline transfer including a reference numeral 43, a horizontal transfer unit 44, and a signal charge detection unit 45.

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

FIGS. 1 and 2 show examples of driving pulses of the solid-state imaging device according to the present embodiment. In FIGS. 1 and 2, a is a composite blanking signal, and b and d are one of four-phase clocks applied to the vertical transfer unit, and are φVA1 in the normal mode and the electronic zoom mode, respectively. c and e are one of the four-phase clocks applied to the storage unit, and represent φVB1 in the normal mode and the electronic zoom mode, respectively.

First, the operation in the normal mode is shown in FIG. 1 and FIG.
This will be described with reference to b and c. During the vertical blanking period A1, the charges accumulated in the vertical transfer unit from the photoelectric conversion unit 41 are transferred by the charge pulse D1. Next, charges are transferred from the vertical transfer unit 42 to the storage unit 43 by the vertical high-speed transfer pulse E1 by the number of stages of the storage unit. At this time, the storage unit 43 is moved three steps earlier. That is, the number of high-speed transfer stages of the storage unit 43 is (the number of stages of the storage unit) +3 stages. Next, in the video scanning period B1, a vertical transfer pulse J1 is applied to the accumulation unit 43 every horizontal scanning period K1, and charges are transferred to the horizontal transfer unit 44 every horizontal scanning period K1.
At the same time, one horizontal scanning period K1, that is, a vertical transfer pulse
During J1, a horizontal transfer pulse having a frequency capable of transferring the signal charge on the horizontal transfer unit 44 for one time is applied to the horizontal transfer unit 44, and the signal charge is output from the signal charge detection unit 45.

Also, charge pulse from the start of vertical blanking period A1
Until D1 is applied, a vertical high-speed transfer pulse H1 is applied to the vertical transfer unit 42, and unnecessary charges on the vertical transfer unit 42 are stored in the accumulation unit 43.
To drain more.

Next, the operation in the electronic zoom mode will be described with reference to FIGS.
This will be described with reference to FIGS. Vertical blanking period A1
During the charge pulse, the charge stored in the photoelectric
The data is transferred to the vertical transfer unit by D1. Next, the electric charge is discharged from the storage section 43 into the semiconductor substrate by one-fourth of the entire screen by the vertical high-speed transfer pulse G1. Next, vertical high-speed transfer pulses F1 and E1 are applied to the vertical transfer unit 42 and the storage unit 43. 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
The vertical high-speed transfer pulse E1 applied to the storage section 43 for one-third stage
Is transferred for (the number of steps of the entire screen + 3) steps. Next, the storage unit 43
The remaining charge of the half-stage remains in the following video period B1,
A vertical transfer pulse J1 is applied to the storage unit 43 at approximately the middle of the horizontal scanning period K1 every two horizontal scanning periods. At the same time, a horizontal transfer pulse having a frequency capable of transferring the signal charge on the horizontal transfer unit 44 for one time is applied to the horizontal transfer unit 44 between the two vertical transfer pulses J1, and the signal charge is output from the signal charge detection unit 45. Then, at the end of the video scanning period B1, the signal charges accumulated in about one quarter of the photoelectric conversion unit 41 on the opposite side to the accumulation unit 43 remain in a part of the vertical transfer unit. This unnecessary signal charge is swept out of the accumulation unit 43 into the semiconductor substrate by the vertical high-speed transfer pulse H1 of the vertical transfer unit 42 at the start of the next vertical blanking period A1.

In the present embodiment, the storage unit is moved three steps earlier than the vertical transfer unit, but the number of preceding stages is arbitrary.

According to the driving method of the solid-state imaging device of the present invention, after the unnecessary charges in the vertical transfer unit are swept out of the storage unit into the semiconductor substrate, the transfer of the storage unit is started earlier than the vertical transfer unit by the number of stages. There is a time difference between the video signal and the unnecessary charge, and no noise occurs during the signal valid period. Therefore, the practical effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a waveform diagram of a pulse for explaining a driving method of the solid-state imaging device of the present invention, and FIG. 2 is a pulse for explaining a driving method of the solid-state imaging device of the present invention. FIG. 3 is an enlarged view of a portion C1 in FIG. 1 for explaining a driving method of the conventional solid-state imaging device, and FIG. 4 is a configuration diagram of the solid-state imaging device. A1… Vertical blanking period, B1… Video scanning period, C1…
Charge pulse, E1, F1, G1, H1 ... vertical high-speed transfer pulse, J1 ... vertical transfer pulse, K1 ... horizontal scanning period, 41 ...
... Photoelectric conversion unit, 42 ... Vertical transfer unit, 43 ... Storage unit, 44 ...
... horizontal transfer section, 45 ... signal charge detection section.

Claims (1)

(57) [Claims] 1. A photoelectric conversion unit in which a plurality of photoelectric conversion elements are two-dimensionally arranged, a vertical transfer unit for vertically transferring signal charges accumulated in the photoelectric conversion unit, and a transfer from the vertical transfer unit. A storage unit for storing signal charges of a plurality of horizontal lines,
A horizontal transfer unit that transfers the signal charges for one horizontal line transferred from the storage unit in the horizontal direction; and a signal charge detection unit that converts the signal charges from the horizontal transfer unit into a signal voltage or a signal current and outputs the signal voltage or signal current. After sweeping out unnecessary signal charges in the vertical transfer unit from the storage unit into the semiconductor substrate, the transfer of the storage unit is started N (N: positive real number) stages earlier than the vertical transfer unit. Driving method of the solid-state imaging device.