JPH0222974A - Solid-state image pickup device driving method - Google Patents

Abstract

PURPOSE:To obtain a still picture with improved resolution and to miniaturize a device by performing the readout of a signal charge equivalent to a frame picture. CONSTITUTION:At the time of reading out the signal charge as also performing an electronic shutter operation by an electronic still camera, frame transfer readout are applied on the signal charges generated in all the image elements. For example, the signal charges of one frame, i.e., the signal charges generated in all the image elements generated in a period to from a time t1 to a time t16. are read out. Thus, since the signal charge equivalent to the frame picture is read out, it is possible to obtain the still picture with superior resolution, and to miniaturize the device.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a driving method for reading out signal charges of a charge storage type solid-state imaging device applied to an electronic still camera.
In particular, the present invention relates to a driving method for reading signal charges while also using an electronic shutter operation.

[Conventional technology]

A frame interline transfer system as shown in FIG. 2 has been devised as a system for a charge accumulation type surface area imaging device (so-called COD, BBD, etc.) applied to an electronic still camera.

First, to explain the structure, in the same figure, a plurality of light receiving elements (pixels) PAII, PA12 to PA+-1PBg,
, PB22-Pe2. , PA31. PA32~P
A3-1PB41. PB, ~PBo etc.) IJ
The light receiving elements PAz and F in odd rows are arranged in a hook shape.
A+z~PA+-, PA31. PA32 to PAsh, etc. are odd-numbered fields, and even-numbered row light receiving elements PB...
BX2 to PB2, Pa, PB, 2 to Pa, etc. are even fields. L, 1. ~11. etc. are charge transfer paths formed in the vertical direction between these light receiving elements, and the upper surfaces of these charge transfer paths 1=, lx to 11, etc. are blocked from light by a shielding film.

Between each light receiving element and the charge transfer path adjacent to it, there is a transfer gate for transferring the signal charge generated in the light receiving element to the charge transfer path.
21~G2□, G3++Gko2~G1n5 G41+
G42 to Gam, etc. are provided. Also, charge transfer path 1
1°12~1r1 etc., charge transfer elements HAII, HAI2~ corresponding to these transfer gates are installed.
HA,,,Ha21. HB2z~He,,,)lA3
1. Further, charge transfer elements LAAll+ LA12 to LA,..., LB21 are provided between the transfer gates for generating HA32 to HAs-, etc., and these charge transfer elements.
．． LB22~LB2-1LA3+, LA32~LA
Other transfer gates are formed for generating 3R and the like.

The region where these light receiving element groups and charge transfer path groups are arranged is a light receiving section for performing imaging, and an accumulation section consisting only of charge transfer paths is provided below the light receiving section. Transfer gates are also provided in the charge transfer path so that the same number of charge transfer elements as in the charge transfer path of the light receiving section are formed. Incidentally, each transfer gate of the light receiving section is provided with a drive signal V I P * V 2Pe V 3P based on a so-called four-phase drive system.
- Drive signals Vlp, V2p, and V3p are applied to each transfer gate of the 1 storage section to which V4F is applied.

Drive signal V I using a four-phase drive force formula with the same period as V4p
s, V2L vss, and V4S are applied.

The upper surface of the storage section is shielded to prevent light from entering.

Furthermore, a horizontal CCD connected to the charge transfer element at the final end of the storage section is provided, and the signal charge transferred from the storage section is converted into a drive signal φ3. It is serially transferred to the output amplifier according to φ2.

Next, the shutter operation and readout operation of this solid-state imaging device will be explained based on FIG. 3.

First, a reset operation is performed to sweep out unnecessary signal charges to the outside. That is, at a certain time 1. , the drive signal V
r p + v3 F I V 4 F is set to "M" level (a level between "H" level and "L" level described later), drive signal V2F is set to "L" level, and further at time t.
2, transfer gates GIlsG12-G, G311G32-G located in odd fields are set to "H" level for a certain period of time by driving signal VIP.
sh, Gs+, G42 to G4n, etc. are turned on and the odd field light receiving elements PAII, PAI2 to PAt are turned on.
-1PA3 r, PA32~PAs-1PAs+,
Unnecessary signal charges such as PAs2 to PAs- are transferred to the charge transfer element, and then, at time t, the drive signal V3 is transferred.
Transfer gate G21+6 located in an even field by setting P to the "H" level for a certain period of time
22~G11ts G41+ G42~G4n, G
gl+ G62 to G11n etc. are turned on and the even field light receiving elements FB2+, PR22 to PB,...P
a...

Transfer unnecessary signal charges such as P842 to Pa, , PB, , pa, □ to PH to the charge transfer element. Then, during a predetermined period TI from the next time t4 to time t, the drive signals VI P # V 2 F, V 2 P +
By performing four-phase driving force type charge transfer using V 4 P, unnecessary signal charges in the light receiving section are transferred to the storage section side, and a reset operation is achieved.

In addition, all the transfer gates are in the off state during this reset operation period, that is, the charge transfer period To for sweeping out the unnecessary signal charges, so that all the light receiving elements perform a photoelectric conversion operation. Then, at a certain time t6, the drive signals V, , V, , are set to "M" level, and the drive signal is set to V3P+.
By setting V4P to the "L" level and further setting the drive signal VIP to the "H2 level" at time t7, the light receiving element PA++ of the odd field.

P A l 2 ~ P A r-1PAst, PA32
~PA! 1, , PAS1, PAS2 to P'As, etc., are transferred to the charge transfer element. Therefore, the - period Ts from time t2 to time t becomes a shutter period for the light receiving elements arranged in odd fields. Next, at time t@, drive signal vsp is set to “H”.
'' level, even field photodetector P
B, l, pet□~PBi, PB31. PB32~
The signal charges generated in PBs1%, PBs+, PBsz to PBs-, etc. are transferred to the charge transfer element.

Therefore, the period T from time t3 to time t6 becomes a shutter period for the light receiving elements arranged in an even field. Note that by making the period from time t2 to time t equal to the period from time t3 to time t, the shutter periods of odd and even fields are made equal.

Next, a predetermined period T from time ts to time tlo.

, all the signal charges of the charge transfer element are transferred to the storage section at high speed, and then, during a period T from time t11 to time t12, serial transfer by the horizontal CCD is performed while parallel transfer is performed row by row to the horizontal CCD. By doing so, the output amplifier outputs the output in chronological order.

The period TO from time t to time t13 is a period during which one still surface is imaged by the electronic still camera.

In this way, the interval Ts between the opening and closing operations of the transfer gate
The shutter period is determined by setting .

[Problem to be solved by the invention]

However, in such conventional solid-state imaging devices, when the signal charges generated in each pixel are transferred to the charge transfer element facing the pixel, the signal charges of two pixels each in the odd field and even field are mixed. Since the signals are transferred, it is essentially possible to obtain only the signal charges of the field image.

As a result, the vertical resolution is 1 of the actually arranged pixels.
There was a problem that the resolution decreased to /2. Further, since the charge transfer path of the storage section requires at least the same number of charge transfer elements as the charge transfer path of the light receiving section, the area occupied by the storage section becomes large, resulting in a problem that the semiconductor chip size becomes large.

[Means to solve the problem]

The present invention has been made in view of such problems,
It is an object of the present invention to provide a driving method that can read out signal charges corresponding to a frame image in an interline type solid-state imaging device having a storage section, and that enables miniaturization of the device.

To achieve this object, the present invention provides a method for driving a solid-state imaging device that detects stationary surface signals using a frame interline transfer type charge accumulation type solid-state imaging device. a first processing step of transferring the signal charge generated in the pixel to the charge transfer path of the light receiving section and then transferring it to the storage section;
a second processing step in which the signal charges generated in the pixels of the remaining field are transferred to the charge transfer path of the light receiving section while the signal charges are held in the storage section; A third processing step of outputting the signal charges in the storage section in time series via the horizontal COD, and a third processing step in which the signal charges corresponding to the pixels of the remaining field held in the charge transfer path are transferred to the storage section and then The signal charge in the storage section is converted to horizontal CC
It was decided that signal charges corresponding to a frame image would be read out by the fourth processing step of outputting them in time series via D.

[Effect]

According to such a driving method, signal charges generated in all pixels can be transferred and read out in a frame, so that a still surface with improved resolution can be obtained. Furthermore, since the area of the charge transfer path in the storage section is half that of the charge transfer path in the light receiving section, it is possible to downsize the device.

〔Example〕

An embodiment of the method for driving a solid-state imaging device according to the present invention will be described below with reference to the drawings. It is assumed that the solid-state imaging device to which the driving method of this embodiment is applied is the same solid-state imaging device as shown in FIG.

Next, the shutter operation and readout operation of this solid-state imaging device will be explained based on FIG. 1.

First, a reset operation is performed to sweep out unnecessary signal charges to the outside. That is, at a certain time t1, the drive signal vl
Pe V3PT V4F at “M” level (intermediate level between “H” level and “L” level), drive signal V2F
is set to "L" level, and furthermore, at time t2, the drive signal VIP is set to "H" level for a certain period of time, so that the transfer game (G+) located in an odd field is set to "L" level.
, G+i~G1°, G21*G22~G31%
NGTurn on G5llG32~GSh etc. and turn on the odd field light receiving elements PAII, PA12~PAt-,
PAs+.

P to sz~PAs,,PASl, PAS2~PAS-
, etc., are transferred to the charge transfer element, and then,
At time t3, drive signal V3F is set to “H” for a certain period of time.
``transfer game located in an even field by setting the level) G21,622~G20,G41+
642 to G411, G@t, G@2 to G61, etc. are turned on to turn on the even number, I-yield light receiving element PB21. P
e2a-PB2. ,,Pe4t,Pa4i~PB,,,
Unnecessary signal charges such as Pa5t and Pe2a to PB2a are transferred to the charge transfer element. Then, the next time t.

The drive signal VIPs is applied during a predetermined period To from to time ts.
By performing moving blade type (D charge transfer) in the four phases of V2Ps, V3P, and v4P, unnecessary signal charges in the light receiving section are transferred to the horizontal CCD, and a reset operation is achieved.

In addition, all the transfer gates are in the off state during this reset operation period, that is, the charge transfer period To for sweeping out the unnecessary signal charges, so that all the light receiving elements perform a photoelectric conversion operation. Then, at a certain time ts, the item drive signal V Itm V3PI V4F is set to "M'" level.
By setting the drive signal V2F to "L" level and further setting the drive signal VIP to "H" level at time t, the odd field light receiving elements PA++, PA++~PA+1
1, P^31 + P A 32 ~ P A 3 n s
The signal charges generated in P A S l +PA■ to PAs-, etc. are transferred to the charge transfer element. Therefore, the period Ts from time t2 to time t7 becomes a shutter period for the light receiving elements arranged in odd fields.

Next, during the period TRI from time t8 to time t9, the drive signal VIP* V2P* V3P+ V by the four-phase movable blade type is applied.
At 4P+VIL V2S*V3S+V4S, all signal charges in the charge transfer path of the light receiving section are transferred to the storage section. During this period T'g+, all the transfer gates are off, so only signal charges of odd fields are transferred to the storage section.

Next, a predetermined shutter period T starts from time t.

Time t, which has elapsed. In, the drive signal V, .

By setting V2F to "L" level, drive signal V3F to "H" level, and drive signal V4F to "M" level, the transfer game (G21, 6) located in an even field is set.
22 ~G2n, G41tG42 ~G,. , G1
11. G12 ~Gin~ etc. are turned on and the even field light receiving elements PB2I, PL2 ~ P870, B4
1. B42~Pa,l,,Pe5t.

Transfer signal charges such as PBs□ to Pa to charge transfer elements. In this way, time 1. At time tlo, when a predetermined shutter period T has elapsed, the drive signal V, ,
, V, , to "L" level, drive signal V sp to g H
By setting the +'' level drive signal V4F to the "M" level, the shutter period can be made equal to the shutter period for an even field, thereby preventing deterioration in image quality when a - frame image is reproduced.

Next, a predetermined period Ti from time tll to time t12
+I: Alongside drive signal VIIF* V2Pm V3
Drive signal V1 while holding P+ V4F at a constant level.
g. Performs a four-phase partial moving blade type charge transfer operation using only V2SIV3S+V4S, transfers the signal charges for one row of the storage section to the horizontal CCD, and further transfers the horizontal CCD drive signal φ8.
By serially transferring this to the output amplifier by φ2, it is outputted from the output amplifier in time series, and by repeating this output operation for all the signal charges in the storage section, the signal charges of odd fields are outputted in time series.

During this period, the drive signals VIp, V2p, V3p,
By keeping V4p at a constant level, signal charges in the charge transfer path of the light receiving section accumulate in the row of photodiodes from which they are read out, making it possible to suppress the reduction in smear that causes vertical streaks compared to the conventional method. can.

Next, during the period TI2 from time t13 to time t14, the four-phase movable blade type knurl drive signal VIPI V2PI V3PI
At V4PIVIS+V2S+V3$+V4S, all signal charges in the charge transfer path of the light receiving section are transferred to the storage section. During this period TH2, all the transfer gates are off, so only the signal charges of even fields are transferred to the storage section.

Next, during the period T12 from time t15 to time tI6, the drive signal V IS+ v2st V3S+ V
A 4-phase movable blade type charge transfer operation using only 4S is performed, and the signal charges for two rows of the storage section are transferred to the horizontal CCD, and the horizontal CCD drive signal φ1. By serially transferring this to the output amplifier by φ2, it is output from the output amplifier in time series, and by repeating this output operation for all signal charges in the storage section, even field signal charges are output in time series.

Time 1 explained above. Period To from to time tlli
Since the signal charges for one frame, that is, the signal charges generated in all pixels can be read out, the resolution can be doubled compared to the conventional method.

In this embodiment, the case where the signal charges of the odd field are read out first and then the signal charges of the even field are read out, but depending on the mode of use, the signal charges of the even field are read out first and then the signal charges of the odd field are read out. It is clear that signal charges of can be read out.

〔Effect of the invention〕

As explained above, according to the present invention, in the driving method of a solid-state imaging device that detects a stationary surface signal using a frame transfer interline type charge storage type solid-state imaging device, either an odd field or an even field is detected. The first processing step involves transferring the signal charges generated in the pixels of the field to the charge transfer path of the light receiving section and then transferring them to the storage section. a second processing step of transferring the signal charge to the charge transfer path of the light receiving section; and a third processing step of outputting the signal charge of the storage section in time series via the horizontal COD while retaining the signal charge in the charge transfer path. and a fourth step of transferring the signal charges corresponding to the pixels of the remaining field held in the charge transfer path to the storage section and then outputting the signal charges of the storage section in time series via the horizontal CCD. Since the signal charges corresponding to the frame image are read out through the processing steps, it is possible to obtain a still surface with improved resolution. Further, in a conventional solid-state imaging device equipped with a storage section, the light receiving section and the storage section are approximately the same size due to the driving method, but according to the present invention, the storage section can be made approximately half the size of the light receiving section. Therefore, the size can be reduced compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a timing chart for explaining an embodiment of the method for driving a solid-state imaging device according to the present invention, FIG. 2 is a block diagram symbolically showing the structure of the solid-state imaging device, and FIG. 3 is a conventional solid-state imaging device. 2 is a timing chart for explaining the drive device of FIG. PAII, P^, 2~PA1, 1, PA3+, PAI2~PA,,, PAs+, PAsa~PAs-; Photodetector (odd field) Pe2t, PBz*~PH,,, Pe4t, PB42~PR4,, Pe5t, Peg2~Pa,; Light receiving element (even field) Gll・G32~G3h s G31・G32
~G3h 5Gs1. Gs2~Gs! I, G21. G
22~Gth 5G41+G42~G4R, G@1sG
12~G6°; Transfer gate 111.1z---I! , ;charge transfer path HAI1. H.A.
12~HA+-5HA31. HA32~HA3-1HA
s+, HAs2~) IAshSHBz+, HB22~H
B2-1HB,,, )1842~Ha,,,HB=+
, Ha, 2~He; charge transfer element-4'

Claims (1)

[Claims] In a method for driving a solid-state imaging device for detecting stationary surface signals using a frame interline transfer type charge storage solid-state imaging device, a signal generated in a pixel of either an odd field or an even field is provided. A first processing step in which the signal charge is transferred to the charge transfer path of the light receiving section and then transferred to the storage section, and a signal charge generated in the pixels of the remaining field is transferred to the light receiving section while the signal charge is held in the storage section. a second processing step of transferring the signal charges to a charge transfer path; and a third processing step of outputting the signal charges in the storage section in a time-series manner via a horizontal CCD while retaining the signal charges in the charge transfer path of the light receiving section. and a fourth processing step of transferring the signal charges corresponding to the pixels of the remaining fields held in the charge transfer path to the storage section and then outputting the signal charges of the storage section in time series via the horizontal CCD. A method for driving a solid-state imaging device, characterized in that signal charges corresponding to a frame image are read out by: