JPS61156880A - Driving system for charge transfer device - Google Patents

Abstract

PURPOSE:To enable accurate action even when timing errors generate to drive pulse signals, by a method wherein the phase of drive pulse signals is previously shifted in a given amount. CONSTITUTION:During the period when the drive pulse signal of a transfer electrode 1 changes from low level to high level, the phase of each drive pulse signal is set so that the drive pulse signals of the transfer electrode 2 and the final stage electrode 3 both may come into high level. With the respect to charge transfer using these drive pulse signals, at a timing t9 charges accumulate under the transfer electrode 2 of higher potential and the final stage electrode 3. At timings t10, t11 charges are not transferred because of high potentials of the transfer electrode 2 and the final stage electrode 3. At a timing t12 the potentials of the electrodes 2 and 3 decrease, and the charges having accumulated in the transfer electrode 2 are transferred to the transfer electrode 1 in the transfer direction, whereas the charges having accumulated in the final stage transfer electrode 3 are transferred to the output part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for driving a charge transfer device, and particularly to a method for driving a charge transfer device that transfers charge between a plurality of electrodes using drive pulse signals having different phases. .

[Technical background of the invention]

FIG. 3 shows an example of a charge transfer device conventionally used in COD and the like. Electrode belonging to the first electrode group (transfer electrode 1)
and electrodes belonging to the second electrode group (transfer electrodes 2) are alternately arranged on the charge transfer layer 8 on the substrate 7. Board 7
A front electrode 9 is provided. - A driving pulse signal is given to each electrode, but generally the volume of the electrode,
Therefore, the waveform of this pulse signal is somewhat distorted. In order to prevent the waveform rounding from causing an adverse effect even if the device is operated at high speed, a drive pulse signal of a different system is usually applied to the final stage electrode 3 for extracting the charge. The charge passes through the final stage electrode 3 and is led to the output section 5 via the output electrode 4.

FIG. 4 shows a drive pulse signal conventionally used to drive such a charge transfer device.

The drive pulse for the transfer electrode 1 has a phase exactly inverted with respect to the drive pulse for the transfer electrode 2 and the final stage electrode 3. FIG. 5 shows how charge is transferred using such a drive pulse signal. 1, 12, and 13 in FIG. 5 correspond to timing 1, 1, 1, and 13 in FIG. 4, respectively. 1. The potential distribution and accumulated charge 6 at 1 are shown. Note that the potential is shown to increase as it goes downward in the diagram. At tl, charges are accumulated under the transfer electrode 2 and the final stage electrode 3, which have a high potential.

At t2, the potential of transfer electrode 1 is not higher than that of transfer electrode 2, so the charges accumulated in transfer electrode 2 are not transferred. Since the final stage electrode 3 has a higher potential than the output electrode 4, the charge accumulated in the final power supply 1i3 is not transferred. At t3, transfer electrode 2 has a lower potential than transfer electrode 1, so the charge accumulated on transfer electrode 2 is transferred to the bottom of transfer electrode 1 in the transfer direction, and similarly, the charge accumulated on final stage electrode 3 is output. Transferred to Department 5.

[Problems with Background Art] The method described above requires three systems of drive pulse signals, as shown in FIG. However, since each of these signals is generated by a separate circuit, the timing may deviate somewhat from the desired timing, as shown in FIG.

The operation when such a timing error occurs is not shown in FIG.

At °t4, charges are accumulated under the transfer electrode 2 and the final stage electrode 3, which have a high potential. At t5, the potential of the transfer electrode 2 is low, and the potential of the transfer electrode 1 is also low, so the charges are not transferred and remain accumulated in the transfer electrode 2 and the final stage electrode 3. 1 at t6. This is a state in which the potential of the transfer electrode 1 is about to increase.

The charges accumulated in the transfer electrode 2 are transferred to the final stage electrode 3 through the transfer electrode 1, and are mixed with the charges accumulated in the final stage electrode 3. At t7, all the charges accumulated in the transfer electrode 2 have been transferred, but some of them are transferred to the transfer electrode 1.
The remaining charges are mixed and accumulated in the final stage electrode 3. At t8, the potential of the final stage electrode 3 becomes low, and the charges accumulated in the final stage electrode 3 are transferred to the output section 5.

As described above, if the timing of the drive pulse is shifted, charge may be mixed in, which is a serious drawback.

(Objective of the Invention) Therefore, an object of the present invention is to provide a method for driving a charge transfer device that operates accurately even if a timing error occurs in a driving pulse signal.

[Summary of the invention]

The characteristics of the present invention are that electrodes belonging to the first electrode group and electrodes belonging to the second electrode group are arranged alternately, and a final stage electrode is arranged further after the last stage electrode of this arrangement, and In the method of driving a charge transfer device, the charge transfer device performs charge transfer between each electrode by applying a drive pulse signal having a predetermined phase to each of the electrode group, the second electrode group, and the final stage electrode. During the period in which the signal applied to the first electrode group changes from low level to high level, the signals applied to the second electrode group and the final stage electrode are both at high level or both at low level, and the drive pulse The point is that it operates accurately even if a timing error occurs in the signal.

[Embodiments of the invention]

The present invention will be described below based on illustrated embodiments. 1st
The figure shows each drive pulse signal in the method according to the invention. Fig. 1<8) shows that during the m period in which the drive pulse signal of transfer electrode 1 changes from low level to high level, the drive pulse signal of transfer electrode 2 and the final stage is controlled so that both the drive pulse signal of pole 3 becomes high level. Sets the phase of the drive pulse signal.

In FIG. 1(b), the phase of each drive pulse signal is set so that the drive pulse signals of the transfer electrode 2 and the final stage electrode 3 both become low level during the same period.

In the conventional method shown in FIG. 4, two signals whose phases are exactly inverted are used, but in the method according to the present invention, one signal is further in phase by a certain amount after being inverted. The signal is shifted. The fixed amount by which this phase is shifted is made larger than the phase displacement based on the timing error of each signal.

FIG. 2(a) shows the state of charge transfer using the drive pulse signal shown in FIG. 1(a). At t9, charges are accumulated under the transfer electrode 2 and the final stage electrode 3, which have a high potential. tlor is a state in which the potential of the transfer electrode 1 is about to rise. Transfer electrode 2 and final stage electrode 3
Since the potential of is high, no charge is transferred. tl
At 1, the potential V of the transfer electrode 1 is high. t
l Uniformly, no charge is transferred. At t1□, transfer electrode 2
The potential of the final stage electrode 3 is low (and the potential of the transfer electrode 2
The charges accumulated in the final stage electrode 3 are transferred to the transfer electrode 1 in the transfer direction, and the charges accumulated in the final stage electrode 3 are transferred to the output section 5.

Next, FIG. 2(b) shows the state of charge transfer using the drive pulse signal shown in FIG. 1(b). At t13, charges are accumulated under the transfer electrode 2 and the final stage electrode 3, which have a high potential. At t14, the potentials of the transfer electrode 2 and the final stage electrode 3 are low. The charge accumulated in transfer electrode 2 is transferred! Since the potential of fil is also low, it is not transferred. Furthermore, the charges accumulated in the final stage electrode 3 are transferred to the output section 5. At t15, transfer electrode 1
The potential is on the verge of increasing.

The charge accumulated in transfer electrode 2 is transferred to transfer electrode 1 in the transfer direction.
will be forwarded to. At t16, the potential of the transfer electrode 1 is high, and charges are accumulated in the transfer electrode 1 and the output section 5.

Here, it is assumed that a timing error occurs in each pulse signal shown in FIG. 1(a) or (b). Even in this case, as long as the phase shift due to the timing error is less than a certain amount by shifting the phase in advance as described above, the same operation as described above is possible, and the charges will not be mixed as in the conventional method. There will be no problems such as

〔Effect of the invention〕

As described above, according to the present invention, in the method for driving the charge transfer device, the phase of the drive pulse signal is shifted by a certain amount in advance, so that accurate operation is possible even if a timing error occurs in the drive pulse signal.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are explanatory diagrams showing drive pulse signals used in the method according to the present invention, and FIGS. 2(a) and (b)
) is an explanatory diagram showing the state of charge transfer by the method according to the present invention, FIG. 3 is an explanatory diagram of a conventional charge transfer device, FIG. 4 is an explanatory diagram showing the drive pulse signal used in the conventional method, and FIG. is an explanatory diagram showing the state of charge transfer by the conventional method;
The figure is an explanatory diagram showing a state in which a timing error occurs in the drive pulse signal used in the conventional method, and FIG. 7 is an explanatory diagram showing the state of charge transfer when a timing error occurs in the conventional method. 1... Transfer electrode belonging to the first electrode group, 2... Second
transfer electrode belonging to the electrode group, 3... final stage electrode, 4...
... Output electrode, 5... Output section, 6... Accumulated charge, 7
... Substrate, 8... Charge transfer layer, 9... Counter electrode. Figure 1 (α9 (b) Figure 2 (α9 Figure 2 (b) Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] Electrodes belonging to a first electrode group and electrodes belonging to a second electrode group are arranged alternately, and a final stage electrode is arranged further after the last stage electrode of this arrangement, 1 electrode group, the second electrode group
A method for driving a charge transfer device that performs charge transfer between each electrode by applying a drive pulse signal having a predetermined phase to each of the electrode group and the final stage electrode, the method comprising: It is characterized in that during a period in which the signal applied to the group changes from low level to high level, the signals applied to the second electrode group and the final stage electrode are both at high level or both at low level. A method of driving a charge transfer device.