JPH0645576A - Solid-state image pick-up device - Google Patents

Abstract

PURPOSE:To impart a high transfer efficiency to a horizontal charge coupled device even if the picture element pitches in an image region are large while horizontal length is long. CONSTITUTION:The title solid-state image pick-up element is provided with a pitch decreased dummy region 4 wherein the pitches between the charge coupling element lines connecting from the vertical charge coupling element 2 lines become smaller toward a horizontal charge coupling element 5. With this decrease in the pitch, the stepped pitch of the horizontal charge coupled device 5 can be made finer thereby enabling the whole length thereof to be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device for converting two-dimensional image information into a time series electric signal.

[0002]

2. Description of the Related Art In a conventional solid-state image pickup device, photodetection elements are two-dimensionally arranged in an image area, and vertical charge-coupled elements are provided between the photodetection element rows. A dummy region is provided between the charge coupled device and the charge coupled device. The pitch of the charge-coupled device rows in this dummy region is the same and constant as the pitch of the vertical charge-coupled device columns in the image region. Therefore, the pixel pitch of the image region and the step pitch of the horizontal charge-coupled devices are the same. Has become.

[0003]

In driving a two-dimensional solid-state image pickup device, all the horizontal transfer stages are performed for each vertical transfer stage, so that the drive frequency of the horizontal charge coupled device is extremely high. Generally, the transfer efficiency of the charge coupled device decreases as the driving frequency increases. Therefore, the quality of the transfer efficiency of the horizontal charge coupled device greatly affects the device performance. Since the electric field inside the channel, which has a strong correlation with the transfer efficiency of the charge-coupled device, is inversely proportional to the square of the channel length, even if the number of stages of the charge-coupled device is the same, if the total length is long and the stage pitch is large, the transfer efficiency will accelerate. to degrade. In the conventional solid-state imaging device, the pixel pitch in the image region and the step pitch of the horizontal charge-coupled device match as described above. Therefore, there is a drawback that the transfer efficiency of the horizontal charge coupled device is deteriorated when the pixel pitch is increased.

An object of the present invention is to provide a solid-state image pickup device which does not deteriorate the transfer efficiency of the horizontal charge coupled device even when the pixel pitch of the image region is large and the horizontal length is long.

[0005]

According to a first aspect of the present invention, photo-detecting elements are arranged two-dimensionally, and photo-signal charges are transferred from the photo-detecting elements by a combination of vertical charge-coupled elements and horizontal charge-coupled elements. In the solid-state imaging device for outputting as a time-series electric signal from the photo-detector, the charge-coupled device array connected from the vertical charge-coupled device array in the image region is provided between the image region where the photodetector is two-dimensionally arranged and the horizontal charge-coupled device. It is characterized in that a pitch-reducing dummy region in which the pitch between them decreases as it approaches the horizontal charge coupled device is provided.

A second aspect of the invention is characterized in that, in the first aspect of the invention, the number of stages of the pitch-reduced dummy region is equal to or more than the total number of stages of the image region and dummy stages associated with the image region.

Furthermore, a third aspect of the present invention is the first aspect of the present invention, further comprising a first read control gate between the image area and the pitch-reducing dummy area, and storing between the pitch-reducing dummy area and the horizontal charge coupled device. And a second read control gate, and the image region and the pitch reduction dummy region are separate drive systems.

[0008]

In the solid-state imaging device of the first aspect of the invention, as the pitch between the charge coupled device rows connected from the vertical charge coupled device row in the image area between the image area and the horizontal charge coupled element approaches the horizontal charge coupled element. Since the dummy area for decreasing the pitch is provided, the step pitch of the horizontal charge coupled device can be made fine and the total length can be shortened even if the pixel pitch becomes large. Therefore, high transfer efficiency can be provided.

When the pitch reduction amount of the pitch reduction dummy area is large, if the number of stages is small, the stage pitch of the charge coupled device at the end becomes extremely large, and there is a risk of defective transfer. For this reason, it is necessary to increase the number of steps of the pitch-reducing dummy area according to the pitch reduction amount. Under the condition that the signal output period and the vertical blanking period are defined, the ratio of the number of stages of the pitch reduction dummy region to the number of vertical stages of the image region does not exceed the ratio of the vertical blanking period and the signal output period. There is no problem if it exceeds, but if it exceeds the pitch reduction dummy area, the transfer frequency must be changed and raised by the number of stages corresponding to the number of dummy areas.

In the solid-state imaging device of the second invention, the transfer frequency is changed because the number of steps in the pitch-reduced dummy area is equal to or more than the number of steps in the image area and the number of dummy steps accompanying the image area. Only by driving the image region and the pitch reduction dummy region with exactly the same drive signal, a delay of one field period occurs, but an output signal satisfying the ratio of the vertical blanking period and the signal output period is obtained. be able to.

The above-mentioned structure has a problem that the element size becomes large when the pitch reduction amount of the pitch reduction dummy region is large. The solid-state imaging device according to the third aspect of the present invention makes it possible to reduce the size of the device, although the drive system is somewhat complicated.
In the solid-state imaging device according to the third aspect of the invention, the image region and the pitch-reducing dummy region have different drive systems, and the first read control gate is provided between the image region and the pitch-reducing dummy region. The storage portion and the second read control gate are provided between the reduced dummy region and the horizontal charge coupled device.

With this structure, each time the charge for one stage in the image area is transferred to the pitch reduction dummy area by the operation of the first read control gate, the pitch reduction dummy area is made to perform several transfer operations at high speed, Carry charge to the storage. Even if it is said to be high speed, it is sufficient to send the charge for one stage to the accumulating portion during the period when the horizontal charge coupled device transfers all the stages, so it is sufficiently slow compared with the horizontal charge coupled device. The charge carried to the storage is transferred to the horizontal charge coupled device by operating the second read control gate. Even if the transfer efficiency of the pitch-reduced dummy area is somewhat poor, the transfer operation can be repeated to transfer all the transfer leakage charges to the storage section. Therefore, even if the pitch reduction amount of the pitch reduction dummy region is large, the number of steps can be reduced and the element size can be reduced.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the solid-state image pickup device of the first invention. In FIG. 1, photo-detecting elements 1 are two-dimensionally arranged in an image region 3, vertical charge-coupled elements 2 are provided between the photo-detecting element rows, and a pitch between the charge-coupled element rows is provided under the photo-detecting element rows. Is provided with a pitch-reducing dummy region 4 that decreases as the position goes downward. The charge coupled device in the pitch reducing dummy region 4 is continuously connected to the vertical charge coupled device 2 in the image region 3. A horizontal charge coupled device 5 is provided below the pitch reduction dummy region 4. Although not shown in FIG. 1 to avoid ambiguity, it is common to provide a read control gate between the pitch-reducing dummy region 4 and the horizontal charge coupled device 5. An output unit 6 is connected to the end of the horizontal charge coupled device 5.

Next, the operation of this embodiment will be described.
The operation of this embodiment is similar to the conventional one. After the signal charge generated by photoelectric conversion in the photodetector 1 is accumulated for a certain period of time, the signal charge is transferred from the photodetector group to the vertical charge coupled device array. After transferring the signal charges, the photodetector element 1 is again in the photoelectric conversion and charge storage operation state. In one horizontal period, the vertical charge-coupled device row and the charge-coupled device group in the pitch reduction dummy region 4 transfer one horizontal line portion to the horizontal charge-coupled device 5 by the charge transfer operation downward by one stage, and the horizontal charge-coupled device 5 is transferred. The operation of sequentially reading out from 5 through the output unit 6 is performed. This reading of one horizontal line is repeated every horizontal period, and all pixels including the dummy are read during the accumulation period of the photodetector 1. Therefore, the signal charges read to the vertical charge coupled device column are sequentially read out to the outside after the horizontal period corresponding to the number of stages of the pitch reduction dummy region 4.

As shown in FIG. 1, in the solid-state image pickup device of the present invention, the step pitch of the horizontal charge-coupled device can be made finer than the pixel pitch of the image area and the total length can be made shorter than the horizontal length of the image area. The efficiency can be increased.

Although not included in the embodiment, a dummy attached to the image area may be provided in addition to the pitch reduction dummy area.

FIG. 2 is a plan view showing an embodiment of the solid-state image pickup device of the second invention. Similar to the image area 3 of the first embodiment of the present invention, photodetector elements are two-dimensionally arranged in the m-stage image area 8, and vertical charge-coupled elements are provided between the photodetector element rows. Further, in the (l + m + n) -step pitch reduction dummy region 10, as in the pitch reduction dummy region 4 of the embodiment of the first invention, a charge-coupled device group whose pitch decreases as it goes downward is provided. These are omitted in FIG. 2 for simplicity. m stage image area 8
A dummy 7 on the 1st stage image area is provided above
An n-step image area lower dummy 9 is provided between the step image area 8 and the (l + m + n) step pitch reduction dummy area 10. The l-th stage image area upper dummy 7 and the n-th stage image area lower dummy 9 are the dummy attached to the image area. Therefore, it is necessary to provide (l + m + n) stages or more, which is the sum of the number of stages of the dummy on the image region, the dummy on the image region, and the dummy on the lower region of the image region.

Next, the operation of this embodiment will be described.
After the signal charge generated by photoelectric conversion in the photodetector in the m-stage image area 8 accumulates for a certain period of time, the signal charge is transferred from the photodetector group to the vertical charge coupled device column. After transferring the signal charge, the photodetector element is again in the photoelectric conversion and charge storage operation state. During the one horizontal period, the dummy 7 on the l-th stage image area and the image area 8 on the m-th stage image area
Vertical charge-coupled device array in the n-stage image area lower dummy 9
And the charge coupled device group in the (l + m + n) stage pitch reduction dummy region 10 transfers one horizontal line portion to the horizontal charge coupled device 5 by the charge transfer operation downward by one stage, and the horizontal charge coupled device 5 outputs the output portion 6 from the horizontal charge coupled device 5. Then, the reading operation is sequentially performed to the outside.

This reading of one horizontal line is repeated every horizontal period, but all the charges in the l-stage image area upper dummy 7, the m-stage image area 8 and the n-stage image area lower dummy 9 are (l + m + n) steps. At the time of moving to the pitch-reducing dummy area 10, the signal charges are transferred from the photodetecting element group to the vertical charge-coupled device row in the m-stage image area 8 again. Therefore, a signal having a vertical blanking period corresponding to the sum of the number of stages of the l-stage image area upper dummy 7 and the n-stage image area lower dummy 9 is output to the outside with a delay of one field period. It The ratio of the required vertical blanking period to the signal output period is (l +
If the ratios of n) stages to m stages are matched, the output signal satisfies the requirement.

If the number of stages of the pitch-reduced dummy area is larger than the total number of steps of the image area and the number of dummy steps associated with the image area, all the charges of the image area and the dummy charges associated with the image area are reduced in pitch. After moving to the dummy area, dummy transfer is performed by the number of excess stages of the pitch-reducing dummy area, and then the signal charges are transferred from the photo-detecting element group to the vertical charge coupled element column in the image area.

As described above, in the present embodiment, even if it is necessary to increase the number of stages because the pitch reduction amount of the pitch reduction dummy area is large, a delay of one field period is required, but the driving is not much different from the conventional driving. Thus, it is possible to obtain an output signal that satisfies the ratio of the vertical blanking period and the signal output period.

FIG. 3 is a plan view showing an embodiment of the solid-state image pickup device of the third invention. In the image area 3,
Similar to the first embodiment of the invention, the photo-detecting elements are arranged two-dimensionally, and the vertical charge coupled elements are provided between the photo-detecting element rows. Also in the pitch reduction dummy region 4, as in the first embodiment of the present invention, a charge-coupled device group whose pitch decreases as it goes downward is provided. These are omitted in FIG. 3 for simplicity. A first read control gate and its electrode 11 are provided between the image area 3 and the pitch reduction dummy area 4, and a storage portion and its control electrode 12 are provided between the pitch reduction dummy area 4 and the horizontal charge coupled device 5.
And the second read control gate and its electrode 13 are continuously provided.

In this embodiment, both the image area 3 and the pitch reduction dummy area 4 have four phases.
Image region vertical charge coupled device drive signal 14 (φV1
φV4) and pitch reduction dummy area charge coupled device drive signal 16 (φD1 to φD4). Further, the horizontal charge-coupled device 5 shows a case of two phases, and is driven by the horizontal charge-coupled device drive signal 19 (φH1, φH4). The type and drive signal of these charge-coupled devices may be in different phases.

Next, the operation of this embodiment will be described.
After the signal charges generated by photoelectric conversion in the photodetection elements in the image area 3 are accumulated for a certain period of time, the signal charges are transferred from the photodetection element group to the vertical charge coupled device column. After transferring the signal charge, the photodetector element is again in the photoelectric conversion and charge storage operation state. In one horizontal period, the vertical charge coupled device column transfers one horizontal line to the pitch reduction dummy region 4 through the first read control gate by the charge transfer operation downward by one stage, and the first read control gate After the closed state, the pitch-reducing dummy region 4 repeats the high-speed transfer operation several times to send one horizontal line portion to the storage unit, and the second read control gate is opened to set one horizontal line from the storage unit to the horizontal charge coupled device 5. The line portion is transferred, and the horizontal charge coupled device 5 and the output unit 6 are sequentially read out to the outside. This reading of one horizontal line is repeated every horizontal period, and all pixels including the dummy are read during the accumulation period of the photodetector.

In the present embodiment, the transfer operation is repeated several times for one horizontal line even if the transfer efficiency of the pitch-reduced dummy area is somewhat poor, so that all transfer leakage charges can be carried to the storage section. Therefore, as shown in FIG. 3, the proportion of the pitch-reducing dummy region can be reduced, and the element size can be reduced.

Although not provided in this embodiment, a dummy attached to the image area may be provided in addition to the pitch reduction dummy area.

[0028]

As described above, in the solid-state imaging device of the first invention, the step pitch of the horizontal charge coupled device can be made finer than the pixel pitch of the image area, and the total length can be made shorter than the horizontal length of the image area. The effect is that the transfer efficiency can be increased.

Further, in the solid-state image pickup device of the second invention, the number of stages of the pitch-reduced dummy region is equal to or more than the number of stages of the image region and the number of dummy stages associated with the image region, so that good transfer can be performed. It has the effect that it can be performed.

Further, in the solid-state image pickup device of the third invention, since the transfer operation is repeated several times for one horizontal line, all the transfer leakage charges can be carried to the storage portion, so that the pitch reduction dummy region can be made small, and the device can be made small. This has the effect of reducing the size.

[Brief description of drawings]

FIG. 1 is a plan configuration diagram showing an embodiment of a solid-state imaging device of the first invention.

FIG. 2 is a plan configuration diagram showing an embodiment of a solid-state imaging device of the second invention.

FIG. 3 is a plan configuration diagram showing an embodiment of a solid-state imaging device of the third invention.

[Explanation of symbols]

 1 Photodetector 2 Vertical charge-coupled device 3 Image area 4 Pitch reduction dummy area 5 Horizontal charge-coupled device 6 Output part 7 l stage image area upper dummy 8 m stage image area 9 n stage image area lower dummy 10 (l + m + n) stage pitch Reduced dummy region 11 First read control gate and its electrode 12 Storage part and its control electrode 13 Second read control gate and its electrode 14 Image region Vertical charge coupled device drive signal 15 First read control signal 16 Pitch reduced dummy region Charge coupled Device drive signal 17 Storage unit control signal 18 Second readout control signal 19 Horizontal charge coupled device drive signal

Claims (3)

[Claims] 1. A solid-state imaging device in which photo-detecting elements are two-dimensionally arranged, photo-signal charges are transferred from the photo-detecting elements by a combination of vertical charge-coupled elements and horizontal charge-coupled elements, and output as time-series electrical signals from an output section. In the device, the pitch between the charge-coupled device rows connected from the vertical charge-coupled device row in the image area approaches the horizontal charge-coupled element between the image area in which the photodetection elements are two-dimensionally arranged and the horizontal charge-coupled element. A solid-state image sensor, comprising: a pitch-reducing dummy region that decreases in accordance with the above. 2. The solid-state imaging device according to claim 1, wherein the number of stages of the pitch-reduced dummy region is equal to or more than the number of stages of the image region and the number of dummy stages accompanying the image region. element. 3. The solid-state imaging device according to claim 1, further comprising a first read control gate provided between the image region and the pitch reduction dummy region, and a storage unit provided between the pitch reduction dummy region and the horizontal charge coupled device. And a second read control gate, wherein the image area and the pitch-reducing dummy area are separate drive systems.