JPS62104076A - Driving method for charge coupled device - Google Patents

Abstract

PURPOSE:To drive a CCD solid stage image pickup element without disturbance of longitudinal moire by repeating plural times sorting operations of signal charges from vertical shift register group to horizontal shift register group, thereby preventing the transferring efficiency from being deteriorated. CONSTITUTION:Signal charges 11 of vertical shift registers 101, 103, 105 corresponding to a pulse phiH1 at times t13, t14 are transferred to horizontal transfer electrodes 152, 156, 160 of a horizontal shift register 111. signal charges 13 transferred to transfer gate electrode 141 at times t15, t16 are less in the amount corresponding to the remaining charge 12 than the charges 11, the signal charges 13 are transferred and stored to horizontal transfer electrodes 154, 158 corresponding to phiH2 of the horizontal shift register 111, and the signal charges from the shift registers 102, 104, corresponding to phiH2 is transferred and stored to the horizontal transfer electrodes 154, 158 of the register 111. Similar operationis repeated to combine the charge 13 with the remaining charge 12.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for driving a charge-coupled device having a plurality of vertical shift registers and a plurality of horizontal shift registers.

(Prior Art) In recent years, charge-coupled devices (hereinafter abbreviated as COD) have been researched and developed in a wide range of fields against the backdrop of advances in integrated circuit technology, and have been applied to solid-state image sensors, analog delay lines, field memories, etc. In particular, solid-state imaging devices using COD have many features such as small size, light weight, low power consumption, and high reliability, and their development has been active in recent years. Although there are various structures of such CCD solid-state image sensing devices, a recent noticeable trend is the emergence of structures suitable for increasing the number of pixels and increasing the density.

For example, FIG.
33), in which a plan view of a connecting portion between a vertical shift register and a horizontal shift register is shown.

In this example, by arranging two horizontal shift lenses in parallel, the horizontal element pitch is relaxed, increasing the number of pixels and increasing the density. In the same figure, 101 to 105
is the charge transfer channel of the vertical shift register group, 111$
112 is the charge transfer channel of 82 horizontal shift registers, the final transfer electrode of the 121 vertical shift register group, L3LtL41 is the first and second transfer gate electrode, tSt~160 is the transfer electrode covering the horizontal shift register, 161 163 are charge transfer channels connecting the first and second horizontal shift registers, and 171 to 188 are potential barrier regions formed by, for example, ion implantation.

FIG. 4 is a diagram showing the waveform of a drive pulse applied to each electrode during the horizontal blanking period of a television signal in an example of the method for driving the CCD solid-state image sensor shown in FIG. In the figure, φv4 is a pulse (φTG) applied to the final transfer electrode 121 of the vertical shift register group.
1. φTGttj Soretsure 1st. Pulse applied to the second transfer gate electrode 131°141, φH
1jφ□ are the horizontal transfer electrodes 151 to 160, respectively.
This is the pulse applied to. FIG. 5 shows the potential distribution inside the element overflowing the dashed-dotted line A-A' in FIG. 3 at each time in FIG. 4.

Here, using FIGS. 4 and 5, the CC shown in FIG.
The operation of the D solid-state image sensor will be explained.

First, at time t0, the horizontal charge transfer operation of pulses φ[1, φ□,) is stopped, and a horizontal blanking period begins. At this time, the pulse φv4 is in the on state, and the signal charge transferred downward through the vertical shift register group tot-t05 is transferred to the final transfer electrode 12 of the vertical shift register.
It is stored under 1.

Next, at time tt, pulse φV is turned on, and pulse φ↑01
When transitions to the on state, the signal charge is transferred under the first transfer gate electrode 131 and is accumulated under the transfer gate electrode 131 at time t. At time t, the pulse φTG□ is turned off, and the pulse φR1 applied to one transfer electrode of the horizontal shift register is turned on, and at time t4, among the signal charges, the vertical shift registers Lot and LO3* corresponding to φH1 are turned on. 10
The signal charges 19[ stored under the transfer gate electrode 131 in 5] are transferred to the first horizontal shift register ttt.
Horizontal transfer electrode L 52e corresponding to φshi of L 5
The data is transferred and stored under L l 60 (FIG. 4, time ta).

At this time, the pulse φ? applied to the transfer gate electrode 131? Although Gs is in the off state, the pulse φ■ is in the off state and the potential barrier region 171 exists, so the vertical shift register 102,1 corresponding to φH7
The signal charge from 04, for example 192, remains under the transfer gate electrode 131. Rigini time 1. ．．
1. When the pulse φH1 is turned off and the pulse φTGt is turned on, the signal charge 191 is transferred from the horizontal transfer electrode to which φH1 is applied to the second transfer gate electrode 1.
Transferred and stored under 41. At this time, the signal charge 192 is directly transferred to the first transfer gate electrode 131.
is stored below. Next, time 1, . Pulse φTG at 1a! is off and pulse φH3 is on,
The signal charge 191 is transferred from below the second transfer gate electrode 141 to φH8 of the second horizontal shift register 112.
is transferred below the horizontal transfer electrodes 154 and 158 corresponding to the horizontal transfer electrodes 154 and 158. At the same time, the signal charge 192 from the vertical shift register 102° 104 corresponding to φ■ is transferred from below the agate electrode 131 of the first transformer 7 to the horizontal transfer electrode 154 corresponding to φH8 of the first horizontal shift register 111.
．． Transferred below 158. In this way, the signal charges for every two columns of the vertical shift register group are divided into two horizontal shift registers. After this distribution, at time t, the horizontal blanking period ends and the pulse transfer 8. Since φH1 starts the charge transfer operation in the horizontal direction, each signal charge is transferred in the horizontal direction. However, it was discovered that irregular vertical stripes appeared in the reproduced image. This is due to the fact that signal charges are not distributed with good transfer efficiency from the vertical/ft register group to the horizontal shift register group. That is, C.C.
D solid-state imaging devices are generally designed so that the maximum amount of charge transferred by the horizontal shift register is about 2 to 5 times larger than the maximum amount of charge transferred by the vertical shift register.

Furthermore, as is clear from Figure 3, the channel length of the horizontal shift register is limited by the horizontal element pitch, and as a practical matter, signal charges can be efficiently transferred at a driving frequency several hundred times higher than that of the vertical shift register. For this reason, it is better for the channel length to be short. Therefore, in order to secure the required electrode area, the channel width of the horizontal 7-foot resistor is necessarily set large. Therefore, it is shown in FIG. 3 that the horizontal shift register 1110 transfer electrode 152°L 56. The transfer of charge from below the transfer gate electrode 160 to below the second transfer gate electrode 141 tends to be busy and incomplete due to the long path length.
If there is a charge left below 0, then . This leftover charge is at time t in FIG.

Since the signal charges are mixed with adjacent signal charges in the first horizontal shift register 111, vertical stripes appear in the reproduced image.

The present invention eliminates the above-mentioned conventional drawbacks, and its purpose is to provide a new method for driving a CCD solid-state image pickup device that does not cause vertical stripe interference.

(Means for Solving the Problems) Means provided by the present invention to solve the above-mentioned problems includes a plurality of columns of vertical shift register groups using charge-coupled devices, and charge transfer directions of the vertical shift register groups. M rows of horizontal shift registers formed by charge-coupled device traps arranged in the orthogonal direction, and between the vertical 7-ft register group and the first horizontal shift register of the horizontal shift register group, and the M rows of horizontal shift registers. M transfer gate electrodes are arranged between the groups in parallel with the charge transfer direction of the horizontal shift register group, and the signal charges of each M column from the vertical shift register group are horizontally shifted by the M rows. This is a method of driving a charge-coupled device that distributes the signal charges to each register group, and is characterized by repeating a series of transfer operations required for distributing the signal charges a plurality of times.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Since the element configuration to which this example is applied is the same as the conventional example, reference will be made here to the plan view shown in FIG. 3. FIG. 1 is a waveform diagram showing the waveforms of drive pulses applied to each electrode during the horizontal blanking period of a television signal in an embodiment of the method for driving a CCD solid-state image sensor according to the present invention.

In the figure, φv4 is a pulse applied to the final transfer electrode 121 of the vertical shift register group, φ'rG1 tφTG
Goose is the 11th and 2nd transfer gate electrode t, respectively.
3tt Pulse applied to 141, φH1tφH1
is a pulse applied to the horizontal transfer electrode tSt~160. FIG. 2 is a schematic diagram showing the potential distribution and the flow of signal charges along the dashed line A-A' in FIG. 3 at each time in FIG. Here, the driving method according to this embodiment will be explained using FIGS. 1 to 3. First, at time t1°, the horizontal charge transfer operation of the pulse φIseφH1 is stopped, and a horizontal blanking period begins. At this time, the pulse φv4 is in the on state, and the signal charges transferred downward through the vertical shift register groups 101 to 105 are accumulated under the vertical final transfer electrode 121. Next Fl
Pulse φv4 turns off at y time to # ttz, pulse φ? When Gt is turned on, the signal charge is transferred and accumulated under the first transfer gate electrode 131. Time tlfi # Pulse φTGt at t@4
is off and pulse φH8 is on, the vertical shift register tot corresponding to φH8 among the signal charges is
Transfer gate electrode 13 in t toa, tos
The signal charge 11 accumulated under 1 is transferred to the horizontal transfer electrode 15 corresponding to φH1 of the t-th horizontal Kuftre star 111.
21 L 56. Transferred and stored under 160. At this time, although the pulse φ↑G1 applied to the transfer gate electrode 131 is in the off state, the pulse φH1 is in the off state and the potential barrier region 171 exists, so the vertical shift register t corresponding to φH8 02t
The signal charge (not shown) from L 04 remains below the transfer gate electrode 131 . rigini time t
In tittts, pulse φ■1 is off, pulse φTGI
The signal charge 11 is transferred to the horizontal transfer electrode 152 to which φH1 is applied.
, 156° and 160° below the second transfer gate electrode 141. However, as is clear from the description of the conventional example, this transfer is incomplete due to the long path length under the horizontal transfer electrodes, and as a result, the horizontal transfer electrodes 152. There will be 12 charges left behind at L561160.

For this reason, the signal charges 13 normally transferred below the transfer gate electrode 141 are smaller than the original signal charges 11 by the amount of the remaining charges 12. Next, at time J7 y ill, pulse φ7G1+! -φTG
When t is off and pulses φout and φold are turned on, the signal charge 13 is transferred from below the second transfer gate electrode 141 to φH1 of the second horizontal shift register 112.
It is transferred below the horizontal transfer electrode 1541 15g corresponding to . At this time, the remaining charges 12 are transferred directly to the horizontal transfer electrode 152 corresponding to φH1 of the first horizontal shift register 111. It is stored under tsctt 160.

Further, signal charges (not shown) from the vertical shift registers 102 and 104 corresponding to φ□ are transferred from below the first transfer gate electrode 131 to the horizontal transfer electrode 154 corresponding to φH2 of the first horizontal shift register 111. ,158
transferred to the bottom. Next, current events 1tllll tta
Then /< Lus φ1□□ and φ□, force; off, /f Lus φ
τG1 and φTG are turned on, and the time tts tt
, a similar situation is reproduced. Therefore, a portion 14 of the remaining charge 12 is transferred to the first horizontal register 11.
Horizontal transfer electrode 152.1561 corresponding to φMl of 1
The signal is transferred from below the transfer gate electrode 160 to below the second transfer gate electrode 141. However, even at this point, there is a small amount of charge 1 left under the horizontal transfer electrode 152*L56w160.
5 exists. Next, at time tut and tlt, pulses φTGI and φTGt are off, and pulses φout and φH
8 is turned on, and a state similar to that at time tt'r ttta is reproduced.

Therefore, the leftover charges 14 are transferred to the horizontal transfer electrodes 154 and 158 corresponding to φH8 of the second horizontal shift register 1[2] from below through the second transfer gate ti[t4.
It is transferred downward, where it joins with the signal charges 13 previously accumulated on the electrodes 154 and 158 to form signal charges 16. Thereafter, similar operations are repeated from time t9 to t□. Therefore, at time t2. Then, the signal charge 11 which has also merged with the leftover charge 15 is accumulated under the horizontal transfer electrode 154° 158 corresponding to φH1 of the second horizontal shift register 112. Furthermore, from time t1゜
At t, φH! Vertical shift register 1 corresponding to
The signal charge (not shown) from 02, 104 is transferred to the first horizontal shift register [φH! of 11]. continues to be accumulated under the horizontal transfer electrodes 154+158 corresponding to the horizontal transfer electrodes 154+158. In this way, the signal charges for every two columns of the vertical shift register group are
This means that the data is distributed to two horizontal shift registers. After this distribution, at time 'ht, the horizontal blanking period ends and the pulses φH3 and φH3 start the charge transfer operation in the horizontal direction, so that each signal charge is transferred in the horizontal direction. In this embodiment, the operation for distributing the signal charges is repeated three times, but in order to further improve the transfer efficiency, it is better to increase the number of repetitions as much as possible.

(Effects of the Invention) As described above, in the COD driving method according to the present invention, the operation of distributing signal charges from the vertical shift register group to the horizontal shift register group is repeated multiple times.
Deterioration of transfer efficiency can be prevented. Therefore, if the driving method of the present invention is used, a C
OD solid-state sensor can be driven without disturbing vertical stripes. Although the embodiments of the present invention have been explained limited to COD solid-state image sensors, the present invention also applies to COD analog delay lines,
It can also be applied to driving a CCD field memory, etc.

[Brief explanation of drawings]

FIG. 1 is a drive pulse waveform diagram showing an example of the driving method for a CCD solid-state image sensor according to the present invention, and FIG. A schematic diagram showing the potential distribution and signal charge flow along the line, Figure 3 is 2
FIG. 4 is a drive pulse waveform diagram showing the conventional driving method of the CCD solid-state image sensor, and FIG. FIG. 4 is a schematic diagram showing the potential distribution and the flow of signal charges along the dashed-dotted line A-A' in FIG. 3 in accordance with the method. In the figure, IO1 to 105 are charge transfer channels of the vertical shift register, tttt 112 is a charge transfer channel of the horizontal 77 register, 121 is the final transfer electrode of the vertical shift register, t3tt 141 is a transfer gate electrode, and 151 to 160 are horizontal transfer electrodes. , 161-16
3 is a charge transfer channel coupling the horizontal shift register;
171-tss is a potential barrier region. Figure 2 Figure 3 Δ 101~105 101~105 101ft register -51~
160 Toru Kihira (shi*II+), 112 Obtained Shift and Jista 161-163 Confucian Death Tsutomushima 1
1,000 + z + @; ih prisoner d pole 171-188 potential material 131.141) Figure 5

Claims (1)

[Claims] A group of vertical shift registers with multiple columns using charge-coupled devices,
between a horizontal shift register group of M rows including charge-coupled devices arranged in a direction perpendicular to the charge transfer direction of the vertical shift register group, and a first horizontal shift register of the vertical shift register group and the horizontal shift register group; and said M
M transfer gate electrodes are arranged between horizontal shift register groups in a row in parallel to the charge transfer direction of the horizontal shift register group, and the signal charges for each M column from the vertical shift register group are transferred to the A charge-coupled device driving method for distributing signal charges to each of M rows of horizontal shift register groups, the method comprising repeating a series of transfer operations necessary for distributing the signal charges a plurality of times.