JPH04101581A - Solid state image pickup device - Google Patents

Abstract

PURPOSE:To reduce the smear quantity of both a 1st and a 2nd fields and to obtain a still picture with a clear frame without generating a flicker by individually driving a vertical transfer part and a charge accumulation part. CONSTITUTION:To individually drive a vertical transfer part 2 and a charge accumulation part 3, this solid state image pickup device is provided with a pulse input terminal 6 for driving the vertical transfer part and a pulse input terminal 7 for driving the charge accumulation part in respective parts. Thus, a vertical transfer part transfer pulse (d) of the vertical transfer part 2 and a charge accumulation part transfer pulse (e) of the charge accumulation part 3 are input separately. Therefore, when the signal charge of the 1st field at the charge accumulation part 3 transferred at high speed from the vertical transfer part 2 is being read by an ordinary read pulse x2, the transfer pulse of the vertical transfer part 2 is stopped, and after the whole signal charge of the 1st field is read, a high-speed transfer pulse z3 is input to the vertical transfer part 2, thus transferring at high speed the whole signal charge of the 2nd field to the charge accumulation part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a solid-state image sensor that is most suitable for capturing still images.

BACKGROUND OF THE INVENTION In recent years, solid-state imaging devices have been developed to include a plurality of light receiving sections having a photoelectric conversion function, a vertical transfer section that vertically transfers the signal charges of the light receiving sections, and a vertical transfer section that transfers the signal charges transferred from the vertical transfer sections. Frame interline transfer CCD (FIT-
CCD) is often used.

Hereinafter, a conventional solid-state image sensor will be explained based on the configuration diagram of FIG. 5.

A conventional solid-state image sensor has a first field light receiving element IA.
and a light receiving section l consisting of a second field light receiving element IB,
A vertical transfer section 2 that vertically transfers the signal charges photoelectrically converted by the light receiving section 1; a charge storage section 3 that accumulates the signal charges transferred from the vertical transfer section 2; It consists of a line transfer section 4 that reads signal charges, and a vertical drive pulse input terminal 8 is connected to the vertical transfer section 2 and the charge storage section 3.
A vertical transfer pulse is input from the horizontal drive pulse input terminal 5 to the line transfer section 4, and a horizontal transfer pulse is input from the horizontal drive pulse input terminal 5 to the line transfer section 4.

The operation of capturing a still image using the solid-state image sensor will be described using the time chart shown in FIG. In FIG. 6, the signal a is the vertical blanking pulse, and the signal
The first field charge pulse, signal C, transfers the charge of the field light-receiving element IA to the vertical transfer section 2. The second field charge pulse, signal C, transfers the charge of the second field light-receiving element IB to the vertical transfer section 2. f is vertical transfer section 2
The vertical transfer pulse f is a vertical transfer pulse that transfers the signal charge of the charge storage section 3 in the vertical direction, and the vertical transfer pulse f is a normal read pulse Before the first field charge pulse b, there is a sweep pulse y which is faster than the normal read pulse It consists of three pulses: a high-speed transfer pulse Z that transfers the signal charge in the vertical transfer section 2 to the charge storage section 3.

In addition, in FIG. 6, the first field charge pulse b, the second field charge pulse C, and the vertical transfer pulse f are shown separately for the sake of explanation.The signals that actually drive the solid-state image sensor are these pulses bc, It is a ternary signal that is a combination of f. In addition, the method of transferring signal charges in the vertical transfer section 2 and the charge storage section 3 can be single-phase, two-phase, three-phase, or four-phase, and usually three-phase or four-phase is used, and the number of phases depends on the number of phases. A corresponding signal input is required.

First, when performing imaging, the first field charge pulse b input before a predetermined time (exposure time in FIG. 6)
1 and the second field charge pulse c1.
After transferring unnecessary charges before the start of exposure to the vertical transfer section 2, the subject to be imaged is exposed. Before the first field turn pulse b2 is output at the end of the exposure time, the sweep pulse yl is used to eliminate unnecessary dark components accumulated before the start of exposure and smear components during exposure in the vertical transfer section 2 and charge storage section 3. The charge is swept to the line transfer section 4. After sweeping out all unnecessary charges in the vertical transfer section 2 and the charge storage section 3, the first field light receiving element I accumulated during the exposure time by the first field charge pulse b2
The signal charges of A are transferred to the vertical transfer section 2, and transferred at high speed to the charge storage section 3 in a short period of time by a high-speed transfer pulse Z2.

After all the signal charges of the first field are transferred to the charge storage section 3 at high speed, the signal charges of the second field light receiving element IB are transferred to the vertical transfer section 2 by the second field charge pulse C2. Then, the signal charge of one field is sequentially read from the charge storage section 3 to the line transfer section 4 by the normal read pulse x2 synchronized with the horizontal synchronization signal, and at the same time, the signal charge of the second field is stored from the vertical transfer section 2. Sequentially transfer to section 3. The signal charges read out to the line transfer section 4 are sequentially output by horizontal drive pulses.

Before the start of the second vertical blanking period after the end of exposure, all the signal charges in the first field are read into the line transfer section 4, and at the same time, all the signal charges in the second field are also transferred to the charge storage section 3. . During the second vertical blanking period after the end of exposure (Fig. 6 m), the sweep pulse y and the high-speed transfer pulse Z are stopped, and then the signal charges of two fields are sequentially read out by the normal read pulse X3 synchronized with the horizontal synchronization signal. is read by the charge storage section 3 to the line transfer section 4. The signal charges read by the line transfer section 4 are sequentially output by horizontal drive pulses.

Problems to be Solved by the Invention However, in the configuration of the conventional solid-state image sensing device described above, the signal charges of the vertical transfer section 2 and the charge storage section 3 are transferred using the same signal. Therefore, when reading out the signal charge of the first field of the vertical transfer section 2 to the charge storage section 3, since the signal charge is transferred at high speed and in a short time using the high-speed transfer pulse z2, the vertical smear is very small and there is no problem. When reading out the signal charge of the second field of the transfer section 2 to the charge storage section 3, it is normally transferred by the read pulse x2.
A vertical smear component due to light leaking into the vertical transfer section 2 occurs in the signal charge of the second field being transferred from the vertical transfer section 2 to the charge storage section 3, and therefore the amount of smear between the first field and the second field changes. As a result, flickering occurred, and there were problems in that it was impossible to capture still images of frames.

The present invention solves the above problem, and the amount of smear between the first field and the second field is extremely small.
It is an object of the present invention to provide a solid-state image sensor that can obtain clear frame still images without flickering.

Means for Solving the Problems In order to solve the above problems, the solid-state image sensor of the present invention includes a plurality of light receiving sections having a photoelectric conversion function, a vertical transfer section that vertically transfers signal charges of the light receiving sections, and a plurality of light receiving sections having a photoelectric conversion function. A charge accumulation section that accumulates signal charges transferred from the vertical transfer section; and a drive means that drives the vertical transfer section and the charge accumulation section independently of each other, and the vertical transfer section and the charge accumulation section are provided with independent transfer. It is designed to input signals.

Effect With the above configuration, by driving the vertical transfer section and the charge storage section independently of each other, the signal charges of the plurality of light receiving sections, that is, the first field and the second field, which are independently transferred to the vertical transfer section, can be combined. Since it is possible to transfer charge independently to the charge storage section at high speed and in a short time, the amount of smear in both the first and second fields can be extremely reduced, resulting in a still image with a clear frame without flickering. can get.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings. Note that the same components as those in FIG. 5 of the conventional example are given the same reference numerals and explanations are omitted.

FIG. 1 is a block diagram of a solid-state image sensor according to an embodiment of the present invention.

The solid-state image sensor of the present invention includes a vertical transfer section 2 and a charge storage section 3.
In order to drive the vertical transfer section 2 and the charge storage section 3 independently of each other, the vertical transfer section 2 and the charge storage section 3 are provided with a vertical transfer section drive pulse input terminal 6 and a charge storage section drive pulse input terminal 7, respectively.

The operation of capturing a still image using the solid-state image sensor will be explained using the time chart shown in FIG. Signals that are the same as those in the conventional time chart shown in FIG. 6 are denoted by the same reference numerals, and their explanation will be omitted. In FIG. 2, signal d is a vertical transfer section transfer pulse that transfers the signal charge of vertical transfer section 2 in the vertical direction, and signal e is a charge storage section transfer pulse that transfers the signal charge of charge accumulation section 3 in the vertical direction. . Both the vertical transfer unit transfer pulse d and the charge storage unit transfer pulse e are generated before the normal readout pulse A sweep pulse y that is faster than the normal read pulse X and transfers the unnecessary charge in the vertical transfer section 2 and the charge storage section 3 to the line transfer section 4, and a sweep pulse y that is faster than the normal read pulse X and transfers the unnecessary charge in the vertical transfer section 2 to the line transfer section 4. It consists of three high-speed transfer pulses Z that are transferred to the storage section 3.

However, the signal that actually drives the solid-state image sensor is a four-value signal that is a combination of these pulses b, c, d, and e. Furthermore, the method of transferring signal charges in the vertical transfer section 2 and the charge storage section 3 is single-phase, two-phase, three-phase, or four-phase, or usually three-phase or four-phase. A corresponding signal input is required.

First, when performing imaging, the first field charge pulse b input before a predetermined time (exposure time in FIG. 2)
1 and the second field charge pulse cl.
After transferring unnecessary charges before the start of exposure to the vertical transfer section 2, the subject to be imaged is exposed. Before the exposure time ends, a sweep pulse yn is applied from the vertical transfer unit drive pulse input terminal 6 and the charge storage unit drive pulse input terminal 7, respectively.
and the sweep pulse y12 are sent to the vertical transfer section 2 and the charge storage section 3.
and sweep out pulse y11. y12, unnecessary charges such as dark components accumulated before the start of exposure and smear components during exposure in the vertical transfer section 2 and charge storage section 3 are swept out to the line transfer section 4. Vertical transfer section 2 and charge storage section 3
After sweeping out all unnecessary charges in the field, the first field charge pulse b2 charges the first
The signal charge of the field light-receiving element IA is transferred to the vertical transfer section 2, and is transferred at high speed to the charge storage section 3 during a short period of the vertical blanking period by a high-speed transfer pulse Z2.

After all the signal charges of the first field are transferred to the charge storage section 3 at high speed, the signal charges accumulated in the second field light receiving element IB during the exposure period are transferred to the vertical transfer section 2 by the second field charge pulse C2. Forward. Thereafter, the input of the vertical transfer unit transfer pulse d is stopped, and while the signal charge of the second field transferred to the vertical transfer unit 2 is held in the vertical transfer unit 2, the normal read pulse X2 synchronized with the horizontal synchronization signal is used. Only the signal charges of one field are sequentially read from the charge storage section 3 to the line transfer section 4.

The signal charges read out to the line transfer section 4 are sequentially output by horizontal drive pulses.

When the signal charge of the first field is read from the charge storage section 3 to the line transfer section 4, the vertical transfer section transfer pulse d is supplied again, and the vertical transfer section drive pulse input terminal 6 and the charge accumulation section drive pulse input terminal 7, the same high-speed transfer pulse Z3 is input to the vertical transfer section 2 and charge storage section 3, respectively.

This high-speed transfer pulse Z3 causes the signal charges of the second field held in the vertical transfer section 2 to be transferred to the charge storage section 3 at high speed during a short period of the vertical blanking period.

After all the signal charges of the second field are transferred to the charge storage section 3, a normal read pulse x synchronized with the horizontal synchronization signal
3, the signal charges of two fields are sequentially stored in the charge storage section 3.
The signal charges read by the line transfer unit 4 are sequentially output by horizontal drive pulses.

As described above, according to this embodiment, the vertical transfer section transfer pulse d of the vertical transfer section 2 and the charge accumulation section transfer pulse e of the charge accumulation section 3 can be input separately, so that the vertical transfer section 2 can be driven and the charge accumulation The parts 3 can be driven independently of each other. Therefore, while the signal charge of the first field in the charge storage section 3 transferred at high speed from the vertical transfer section 2 is being read using the normal read pulse X2, the transfer pulse of the vertical transfer section 2 is stopped and the first field is After reading out all the signal charges, input the high-speed transfer pulse Z3 to the vertical transfer section 2,
All the signal charges in the second field can be transferred to the charge storage section 3 at high speed, and in this way, both the signal charges in the first field and the signal charges in the second field can be transferred to the charge storage section 3 at high speed. As a result, the amount of smear in both the first field and the second field can be extremely reduced, making it possible to obtain a still image with a clear frame without flickering.

Other embodiments of the present invention will be described below with reference to the drawings.

Note that the same components as in FIGS. 1 and 5 are designated by the same reference numerals, and explanations thereof will be omitted.

FIG. 3 is a configuration diagram of a solid-state image sensor according to another embodiment of the present invention.

The solid-state image pickup device shown in FIG. 3 is provided with a drive changeover switch 9 for switching between stopping and reading the signal charges of the vertical transfer section 2.

The operation of capturing a still image using the solid-state image sensor will be explained using the time chart shown in FIG. Signals that are the same as those in the time charts of FIGS. 2 and 6 are given the same reference numerals, and their explanations will be omitted. In FIG. 4, the signal f' is a vertical transfer pulse that vertically transfers the signal charges of the vertical transfer section 2 and the charge storage section 3, and is a normal readout pulse synchronized with a horizontal synchronization signal for sequentially reading out video signals. X and the first field charge pulse b during the vertical blanking period.
Before this, there is a sweep pulse y, which is faster than the normal read pulse It consists of three high-speed transfer pulses Z for transferring charges to the charge storage section 3. The signal g is a switching signal of the drive changeover switch 9,
When the switching signal g is at high (H) level, the vertical transfer section 2
When the signal is at low (L) level, the vertical transfer section 2 and the charge storage section 3 are driven by the same signal. Signal 1 is a vertical transfer unit transfer pulse that vertically transfers the signal charge of the vertical transfer unit 2 after being switched by the switching signal g.

However, the signal that actually drives the solid-state image sensor is a four-value signal that is a combination of these pulses b, c, and f'2g. Methods include single phase, 2 phase, 3 phase, and 4 phase, or usually 3 phase.
Phase or four-phase is often used, and a signal input corresponding to the number of phases is required.

First, when performing imaging, the first field charge pulse b input before a predetermined time (exposure time in FIG. 4)
1 and the second field charge pulse C1.
After transferring unnecessary charges before the start of exposure to the vertical transfer section 2, the subject to be imaged is exposed. Before inputting the exposure time or the end of the first field charge pulse b1,
The sweep pulse y1 sweeps unnecessary charges such as dark components accumulated before the start of exposure and smear components during exposure in the vertical transfer section 2 and charge storage section 3 to the line transfer section 4.

After sweeping out all unnecessary charges in the vertical transfer section 2 and the charge storage section 3, the first field light receiving element IA accumulated during the exposure time by the first field charge pulse b2
The signal charge is transferred to the vertical transfer section 2, and the high-speed transfer pulse z
2, the charge is transferred to the charge storage section 3 at high speed during a short period of the vertical blanking period. After all the signal charges of the first field are transferred to the charge storage section 3 at high speed, the signal charges accumulated during the exposure period are transferred to the second field light receiving element IB by the second field charge pulse C2 to the vertical transfer section 2.
Transfer to. Thereafter, the drive changeover switch 9 is switched to stop the transfer of the second field signal charge transferred to the vertical transfer section 2, and while the signal charge of the second field is held in the vertical transfer section 2, the horizontal synchronization signal is Only the signal charges of one field are sequentially read out from the charge storage section 3 to the line transfer section 4 by the normal readout pulse x2 synchronized with .

The signal charges read by the line transfer section 4 are sequentially output by horizontal drive pulses.

When all the signal charges of the first field accumulated in the charge accumulation section 3 are read out from the charge accumulation section 3 to the line transfer section 4, the drive changeover switch 9 is switched to start reading out the signal charges of the vertical transfer section 2. Then, the signal charges of the second field held in the vertical transfer section 2 are transferred to the charge storage section 3 at high speed during a short period of the vertical blanking period by the high-speed transfer pulse Z3. After all of the signal charges in the second field are transferred to the charge storage unit 3, two fields of signal charges are sequentially read from the charge storage unit 3 to the line transfer unit 4 using the normal read pulse x3 synchronized with the horizontal synchronization signal. . The signal charges read by the line transfer section 4 are sequentially output by horizontal drive pulses.

As described above, according to this other embodiment, by switching the drive changeover switch 9 and controlling the transfer of signal charges of the vertical transfer section 2, the driving of the vertical transfer section 2 and the driving of the charge storage section 3 are mutually controlled. Can be done independently. Therefore, the signal charge of the first field in the charge storage section 3 transferred at high speed from the vertical transfer section 2 is normally read out by the pulse x2.
During reading, the drive changeover switch 9 stops the transfer of signal charges in the vertical transfer section 2, and after reading out all the signal charges in the first field, the drive changeover switch 9 is switched to transmit the high-speed transfer pulse Z3. All the signal charges of the second field can be input to the vertical transfer section 2 and transferred to the charge storage section 3 at high speed.In this way, both the signal charges of the first field and the signal charges of the second field can be transferred at high speed. Since it can be transferred to the storage section 3, the amount of smear in both the first field and the second field can be extremely reduced.
You can get clear frame still images without flickering.

Further, in contrast to the embodiment shown in FIG. 1, in this other embodiment, a drive changeover switch 9 is configured inside the solid-state image sensor, so that the signal charges of the vertical transfer section 2 and the charge storage section 3 can be transferred independently. Therefore, it is not necessary to have as many separate drive signals for the vertical transfer section 2 as there are phases, and the number of pins of the solid-state image sensor can be reduced.

Note that during the period in which the signal charges of the second field of the imaging period are sequentially read out from the charge storage section 3 to the line transfer section 4 (Fig. 2, Fig. 4 1), the signal transfer of the vertical transfer section 2 is normally read out. The pulse X may be used, or the signal charge transfer pulse may be stopped.

Further, in FIGS. 2 and 4, after the exposure time is changed to field charge pulses bl and cl to transfer unnecessary charges in the light receiving section 1 to the vertical transfer section 2, the next field charge pulse b2. It is possible to set the period until c2 is inputted (1/60 second before) or set it to an arbitrary time by controlling the input interval of field charge pulses b and c by setting the exposure time.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, by driving the vertical transfer section and the charge storage section independently of each other, a plurality of light receiving sections, that is, the first field, which are independently transferred to the vertical transfer section, The signal charges of the first field and the second field can be independently transferred to the charge storage section at high speed and in a short time.
The amount of smear in both the field and the second field is extremely reduced, making it possible to obtain a still image with a clear frame without flicker.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a solid-state image sensor according to an embodiment of the present invention, FIG. 2 is a time chart of the same solid-state image sensor when capturing a still image, and FIG. 3 is a solid-state image sensor according to another embodiment of the present invention. Fig. 4 is a time chart when capturing a still image with the solid-state image sensor shown in Fig. 3, Fig. 5 is a block diagram of a conventional solid-state image sensor, and Fig. 6 shows still image capturing with a conventional solid-state image sensor. This is a time chart of the time. ■... Light receiving section (IA... Light receiving element for the first field. IB... Light receiving element for the second field), 2... Vertical transfer section, 3... Charge storage section, 4... Line transfer Part, 5
...Horizontal drive pulse input terminal, 6...Vertical transfer unit drive pulse input terminal, 7...Charge storage unit drive pulse input terminal, 8...Vertical drive pulse input terminal, 9...Drive changeover switch , a... Vertical blanking pulse, b
...First field charge pulse, C...Second field charge pulse, d...Vertical transfer section transfer pulse, e...Charge storage section transfer pulse, f, f'...
- Vertical transfer pulse, g... switching signal, X... normal read pulse, y... sweep pulse, 2... high speed transfer pulse.

Claims (1)

[Scope of Claims] 1. A plurality of light receiving sections having a photoelectric conversion function, a vertical transfer section that vertically transfers the signal charges of the light receiving sections, and a charge that accumulates the signal charges transferred from the vertical transfer sections. 1. A solid-state image sensing device, comprising: an accumulation section; and a driving means for driving the vertical transfer section and the charge accumulation section independently of each other. 2. The vertical transfer unit transfer signal that transfers the signal charge of the vertical transfer unit and the charge storage unit transfer signal that transfers the signal charge accumulated in the charge storage unit are input from independent signal input terminals. The solid-state imaging device according to claim 1, characterized in that: 3. It is characterized by having means for stopping the vertical transfer section transfer signal that transfers the signal charges of the vertical transfer section independently of the charge accumulation section transfer signal that transfers the signal charges accumulated in the charge accumulation section. The solid-state imaging device according to claim 1.