JPH06101482B2 - Driving method for charge transfer device - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for driving a charge transfer device, and more particularly to a method for driving a charge transfer device that performs charge transfer 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 used in a conventional CCD or the like. The electrode (transfer electrode 1) belonging to the first electrode group and the electrode (transfer electrode 2) belonging to the second electrode group are formed on the substrate 7
The charge transfer layers 8 are alternately arranged. A counter electrode 9 is provided on the substrate 7. A pulse signal for driving is given to each electrode, but the waveform of this pulse signal is somewhat rounded due to the capacitance of the electrodes in general. Therefore, even if it is operated at a high speed, the final-stage electrode 3 for taking out electric charges is
Normally, a driving pulse signal of another system is given. The electric charges are guided to the output section 5 via the final stage electrode 3 and the output electrode 4.

FIG. 4 shows a drive pulse signal that has been conventionally used to drive such a charge transfer device. The drive pulse of the transfer electrode 1 is in a form in which the phase is exactly inverted with respect to the drive pulses of the transfer electrode 2 and the final stage electrode 3. The state of charge transfer using such a drive pulse signal is described in the fifth
Shown in the figure. Shows a fifth view of t _1, t _2, t ₃ is a timing t ₁ of FIG. 4 respectively, t _2, the potential at t ₃ distribution and accumulated charge 6. The potential is shown to be higher toward the bottom of the figure. At t ₁ , charges are accumulated under the transfer electrode 2 and the final stage electrode 3 having high potential. At t ₂ , the transfer electrode 1 does not have a higher potential than the transfer electrode 2, so the charges accumulated in the transfer electrode 2 are not transferred. Since the final stage electrode 3 has a higher potential than the output electrode 4, the charges accumulated in the final stage electrode 3 are not transferred. At t ₃ , since the transfer electrode 2 has a lower potential than the transfer electrode 1, the charges accumulated in the transfer electrode 2 are transferred to below the transfer electrode 1 in the transfer direction, and the charges accumulated in the final stage electrode 3 are similarly transferred. It is transferred to the output unit 5.

[Problems of background technology]

The above-mentioned method requires drive pulse signals of three systems as shown in FIG. However, since each of these signals is generated by a separate circuit, it may be slightly deviated from the desired timing as shown in FIG.
The operation when such a timing error occurs is shown in FIG.

At t ₄ , the charges are accumulated below the transfer electrode 2 and the final stage electrode 3 having high potential. At t ₅ , since the potential of the transfer electrode 2 becomes low, the potential of the transfer electrode 1 is also low, so that the charges are not transferred and remain accumulated in the transfer electrode 2 and the final stage electrode 3 as they are. At t ₆ , the potential of the transfer electrode 1 is in the state of becoming high. 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 t ₇ , a part of the charge accumulated in the transfer electrode 2 is transferred and part of the charge is transferred to the transfer electrode 1.
In addition, the remaining charge is mixed and accumulated in the final stage electrode 3. At t ₈ , 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. In this way, if the timing of the driving pulse is deviated, charge may be mixed, which is a serious drawback.

[Object of the Invention]

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

[Outline of Invention]

The feature of the present invention is that the electrodes belonging to the first electrode group and the electrodes belonging to the second electrode group are arranged alternately, and the final stage electrode is arranged further after the last stage electrode of this arrangement, A driving method of a charge transfer device for performing charge transfer between respective electrodes by applying a driving 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 the low level to the high level, the signals applied to the second electrode group and the last-stage electrode are both set to the high level or the low level, and the drive pulse The point is that it operates correctly even if a timing error occurs in the signal.

Example of Invention

The present invention will be described below based on illustrated embodiments. First
The figure shows each drive pulse signal in the method according to the invention. FIG. 1A shows the transfer electrode 2 during the period in which the drive pulse signal of the transfer electrode 1 changes from low level to high level.
The phases of the drive pulse signals are set so that the drive pulse signals of the final stage electrode 3 are both at the high level. In FIG. 1B, 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 are both at the low level during the same period. In the conventional method shown in FIG. 4, two signals in which the phases are just inverted are used. However, in the method according to the present invention, one signal is inverted and then the phase is further increased by a certain amount. The signal is shifted. The fixed amount of shifting the phase is made larger than the phase change based on the timing error of each signal.

A state of charge transfer using the drive pulse signal shown in FIG. 1A is shown in FIG. At t ₉ , charges are accumulated under the electrodes of the transfer electrode 2 and the final stage electrode 3 having high potential. At t ₁₀ , the potential of the transfer electrode 1 is about to increase. Since the potentials of the transfer electrode 2 and the final stage electrode 3 are high, charges are not transferred. At t ₁₁ , the potential of the transfer electrode 1 is high. As with t ₁₀ , no charge is transferred. At t ₁₂ , the potentials of the transfer electrode 2 and the final stage electrode 3 become low, the charges accumulated in the transfer electrode 2 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 unit 5. Transferred.

Next, FIG. 2B shows the state of charge transfer using the drive pulse signal shown in FIG. 1B. At t ₁₃ , the charges are accumulated under the electrodes of the transfer electrode 2 and the final stage electrode 3 having high potential. At t ₁₄ , the potentials of the transfer electrode 2 and the final stage electrode 3 are low. The charges accumulated in the transfer electrode 2 are not transferred because the potential of the transfer electrode 1 is also low. Further, the charges accumulated in the final stage electrode 3 are transferred to the output section 5. At t ₁₅ , the potential of the transfer electrode 1 is in the state of becoming high. The charges accumulated in the transfer electrode 2 are transferred to the transfer electrode 1 in the transfer direction. At t ₁₆ , the potential of the transfer electrode 1 is high, and the 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, the same operation as described above can be performed as long as the phase displacement based on the timing error is equal to or less than the predetermined amount in which the phase is shifted in advance as described above, and the electric charge is mixed as in the conventional method. It does not cause any trouble.

〔The invention's effect〕

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

[Brief description of drawings]

1 (a) and 1 (b) are explanatory views showing a drive pulse signal used in the method according to the present invention, and FIGS. 2 (a) and 2 (b) are explanations showing a state of charge transfer by the method according to the present invention. 3 and 4 are explanatory views of a conventional charge transfer device, FIG. 4 is an explanatory view showing a drive pulse signal used in the conventional method, and FIG. 5 is an explanatory view showing a state of charge transfer by the conventional method,
FIG. 6 is an explanatory diagram showing a state where a timing error occurs in a drive pulse signal used in the conventional method, and FIG. 7 is an explanatory diagram showing a state of charge transfer when a timing error occurs in the conventional method. 1 ... Transfer electrode belonging to first electrode group, 2 ... Transfer electrode belonging to second electrode group, 3 ... Final stage electrode, 4 ... Output electrode, 5 ... Output section, 6 ... Stored charge , 7 ... substrate, 8
... Charge transfer layer, 9 ... Counter electrode.

Claims (1)

[Claims] 1. An electrode belonging to a first electrode group and an electrode belonging to a second electrode group are arranged alternately, and a final-stage electrode is arranged further after the last-stage electrode of the arrangement, and the first-stage electrode is arranged. A driving method of a charge transfer device for performing charge transfer between respective electrodes by applying a driving pulse signal having a predetermined phase to each of the electrode group, the second electrode group, and the final stage electrode, The signals applied to the second electrode group and the final-stage electrode are both high level or low level during the period when the signal applied to the first electrode group changes from low level to high level. A method of driving a charge transfer device, comprising: