JPS5918688Y2 - Charge transfer device for imaging - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a composite charge transfer device for imaging in which charge transfer devices are two-dimensionally arranged in series and parallel.

A typical two-dimensional array of a charge transfer device (hereinafter abbreviated as CCD) is a series-parallel-series structure (SPS structure), which is used in memories, image pickup devices, and the like.

When the above two-dimensional array is constructed using a conventional straight channel type CCU (hereinafter referred to as a normal CCD) in which a large number of transfer electrodes are arranged in the charge transfer direction, a series-parallel or parallel-series conversion section is formed. Since the charge transfer directions are orthogonal, there are many problems in electrode arrangement, bus wiring, channel connection, and other points, and the structure becomes complicated.

The meandering channel type charge transfer device (hereinafter abbreviated as MCCD) previously provided in Japanese Patent Application Laid-Open No. 52-55478 utilizes this feature because the charge transfer direction (hereinafter referred to as MCCD) has an elongated structure. Then, the MCCD and the normal CCD
The present inventor previously proposed a two-dimensional array structure by combining the following.

An example is shown in FIG. The channel C of a normal CCD is controlled by the channel stop C5 formed on the semiconductor substrate.
H1°CH2... and MCCD channel CH are formed.

El, E2... are normally CCD transfer electrodes, and are connected to the common bus lines B□, B2 every other time, and are connected to the first
Receives phase transfer voltage φ1 and second phase transfer voltage φ2.

The MCCD includes two transfer electrodes E, , E, and a two-phase transfer voltage φ8. φ5 is applied.

The channel is usually CCD channel CH1°CH
A drain diffusion region is provided at the output end in communication with 2....

To explain the operation of this image sensor, the electrode E1 of the CCD section. When a charge accumulation mode voltage is applied to E2... and an optical image is projected, channels CH1 and CH2
Charges are generated depending on the brightness of the optical image.

Then, when a two-phase transfer voltage is applied to the electrodes E, E2, . . . , as the voltage changes, the charges are transferred in the direction shown by the arrow and enter the channel CH of the MCCD.

In the transfer mode, the MCCD voltages Ea and Eb also have a two-phase transfer voltage φ8. φ5 is applied, and this transfer voltage φ
8. The frequency of φ is set to the value nf, where n5 is the number of channels in the imaging CCD section, and f is the frequency of the transfer voltage φ1゜φ2 of the normal CCD.
Every time signal charges are sent from the D section, all these charges are transferred to the output terminal.

Since a gate electrode Ga and a drain Db are provided at the output end, if the gate electrode Ga is in a passing state, these charges are extracted from the drain D5 to an external circuit.

By combining a normal CCD and an MCCD in this way, the charge transfer directions can be made orthogonal, the structure is not particularly complicated, and a gap is created in the conversion section of the two types of CCDs to transfer charges. A two-dimensionally arrayed charge transfer device that does not cause problems such as reduced efficiency can be realized.

However, due to the demand for larger imaging units, CCD
When attempting to enlarge the area, that is, increase the number of channels and the number of transfer electrodes, the power capacity required for the drive power source increases, the power source becomes larger, and the manufacturing cost also increases.

The present invention aims to solve this problem, and the above-mentioned SPS
The present invention provides a large-sized imaging device in which a plurality of structural imaging units are arranged adjacent to each other, an uneven pixel pitch is prevented from occurring between the imaging units, and the device can be driven by a small-capacity power source. be.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

Note that parts equivalent to those in FIG. 1 are given the same reference numerals.

FIG. 2 shows an embodiment of the imaging charge transfer device according to the present invention, in which the imaging device of FIG. 1 is used as one imaging unit, and three units are arranged adjacently.

That is, the imaging unit consisting of an 8-channel normal CCD and the transfer unit consisting of an MCCD are considered as one imaging unit, and the imaging units are arranged vertically in the drawing, and each imaging unit is separated by a channel stop C3. , each output signal is connected to the drain diffusion layer DA, DB, DC.
is extracted from to the external circuit.

Fig. 3 is a partially enlarged view of Fig. 2, in which a light receiving section is located under every other transfer electrode of a normal CCU configured as a two-phase drive type, and in order to improve its resolution, light is emitted only from a small light receiving area. A window W is provided to allow light to pass through, and the rest is covered with a light shielding layer.

Furthermore, as is clear from the figure, since the window W is also provided in some predetermined bits of the MCCD, continuous captured images without any breaks can be obtained even at the boundaries of the imaging units.

Next, to explain the operation of this image sensor, the electrodes EAI, EA□..., EBI of one group of the normal CCD section
.

E8゜..., E cl, E C2...
・, and one transfer electrode EAa, EBa of MCCD
, Eca, and EDa are applied with a charge storage mode voltage and an optical image is projected, charges corresponding to the brightness of the optical image are generated and stored in the light receiving section under these electrodes.

This charge is sequentially taken out to an external circuit by time-division driving as described below.

First, with the accumulation mode voltage still applied to the electrodes of all imaging units SA, SB, and So, the MCCD
A transfer voltage φ8. is applied to the electrodes EAa and EAb. When φ5 is applied, the charge under the electrode is taken out from DA to the external circuit.

Note that at this point, the transfer gate charge TGA is given a potential corresponding to blocking, for example, zero potential, and normally CC
Charges in section D are not transferred to section MCCD.

When all the charges in the MCCD section are discharged to the outside as output, the transfer voltage φ1. Simultaneously with the application of φ2, a transfer voltage φT6 is applied to the transfer gate electrode TGA in synchronization therewith, so that the charge □ is transferred in the direction of the arrow and enters the channel CHA of the MCCD.

Note that the transfer mode voltage φ8. is applied to the electrodes E Aa and E Ab of the MCCD section. φb remains applied, and its frequency is set to the value nf, where the number of channels of the imaging CCD section is n9, and the frequency of the transfer voltage of the normal CCD is f, so that the MCCD receives charges from each imaging CCD section. All of these charges are transferred to the output terminal each time the charge is received.

An output gate electrode GA and a drain diffusion layer D are provided at the output end.
B is provided, so if the output gate electrode GA is in the passing state, these charges are transferred from the drain DA to the output signal S.
.

It is taken out to the external circuit as. When the electric signal of unit SA is taken out, the transfer electrode EB is used to take out the signal charge of unit S8 to the external circuit.
When a two-phase transfer voltage is applied to . Taken out to the circuit.

After the same process, unit)S.

The signal charge is the drain D. After being taken out to the external circuit, all the imaging units are reactivated.

S8. Transfer electrode of Sc and electrode EAa of MCCD.

An optical image is projected while an accumulation mode voltage is applied to EBa and ECa.

In this way, the signal charges corresponding to the optical image are sequentially extracted in a time-division manner to form a video signal.

FIG. 4 shows the drive voltage waveform in the above-described embodiment.

Of the transfer voltages φ8°φ5 applied to the transfer electrodes of the MCCD, φ8 performs charge transfer in the CCD by single-phase driving set at a constant level.

The transfer method in a normal CCD is also a single-phase drive method in which φ1 is set at a constant level.

Note that as a method for time-divisionally driving the imaging units SA, SB, and Sc as described above, for example, an imaging unit selection signal φ4. φ8. φ.

There is a method of sequentially driving the imaging units using .

These selection signals are at a high level during a period during which all signal charges stored in each imaging unit are taken out to an external circuit, that is, a period corresponding to four periods of the transfer gate electrode voltage φ16.

φ4. φ8. φ. are imaging units SA and SB, respectively.
, SC is a selection signal for selectively driving the selection signals φ4. φ8. −〇 and the aforementioned drive signal φ1. φ
2. φTG, φ8 and φゎ as shown in FIG.
By calculating the logical product using the ND circuit, the drive signal is supplied only to the imaging unit (SA) during the period when φ is at a high level, so the signal charge stored in the SA is sequentially taken out to the external circuit. (imaging unit) SB and SC have an accumulation mode voltage φ8. Only φ□ is applied.

Similarly, during periods TB and Tc, the imaging units) S, , S
C are drive signals φ1, φ2, respectively. Driven by φTG, φ8 and φ5.

In the above embodiment, the number of light receiving sections on the imaging surface is 8 x 4 per imaging unit (3 imaging units).
Although SA, SB, and SC are arranged adjacent to each other, it is possible to further widen the imaging area by increasing the number of photosensitive elements per imaging unit and by increasing the number of imaging units.

As is clear from the above explanation, since the imaging device according to the present invention uses both a normal CCD and an MCCD, electrode arrangement is easy and a large imaging surface can be constructed without creating a cut between adjacent units. This has the advantage that the power supply capacity required to drive the entire device is small.

[Brief explanation of the drawing]

Figure 1 is a conventional composite charge transfer device, Figure 2 is a composite charge transfer device according to the present invention, Figure 3 is an enlarged view of the main part of Figure 2, Figure 4 is a driving waveform, and Figure 5 is a FIG. 6 is a time division drive circuit diagram.

Claims (1)

[Scope of utility model registration request] A straight line that has a plurality of channels parallel to each other, transfer electrodes common to each channel are arranged regularly in the direction of charge transfer along the channels, and light-receiving areas are defined below the transfer electrodes in a predetermined order. a channel type charge transfer device; and a pair of transfer electrodes extending in a charge transfer direction configured to transfer output charges corresponding to each channel in series on the output side of the linear channel type charge transfer device. A meandering channel type charge transfer device and a meandering channel type charge transfer device are arranged adjacently so that their respective transfer electrodes are parallel to form an imaging unit, and a predetermined portion of the image pickup unit under one electrode of the meandering channel type charge transfer device is provided. Also, multiple imaging units are placed adjacent to each other with a defined light receiving area,
A charge transfer device for imaging, characterized in that the arrangement pitch of the light receiving sections is approximately equal between these adjacent imaging units.