JP2799003B2 - Driving method of solid-state image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a driving method of a solid-state imaging device such as a CCD.
In particular, the present invention relates to a driving method of a solid-state imaging device capable of realizing electronic zoom.

(Prior Art) At present, home video cameras are mainly CCD type solid-state imaging devices having 300,000 to 400,000 pixels, and high-performance products with an electronic shutter are selling well. Solid-state imaging devices
Since it has features such as small size, light weight, and high reliability compared to the image pickup tube, it is being developed for a next generation high definition (HD) TV camera. The number of pixels is increased from 1.3 million to 2 million pixels.

(Problems to be Solved by the Invention) In the solid-state imaging device as described above, in order to realize a zoom function for enlarging a part of the screen, conventionally, the only way to enlarge an image signal from the solid-state imaging device is to perform the above-described processing. This requires an apparatus for processing the image signal to be enlarged.

Further, when an attempt is made to add an electronic zoom function to the solid-state imaging device itself, specific methods such as a driving method when electronic zoom is not performed, a method of reading an enlarged area during electronic zoom, and a method of processing the enlarged area are used. There was no.

An object of the present invention is to provide a driving method of a solid-state imaging device that can realize electronic zoom using a multi-pixel solid-state imaging device.

[Structure of the Invention] (Means for Solving the Problems) A feature of the present invention is that a plurality of signal charge accumulating sections for storing signal charges obtained by photoelectric conversion on a semiconductor substrate, and the signal charges of each signal charge accumulating section are stored. An object of the present invention is to provide a driving method having a plurality of modes as described below in driving a solid-state imaging device having a plurality of columns of vertical transfer units to be read and a horizontal transfer unit to read signal charges of the vertical transfer units. That is, one mode is a high sensitivity or standard mode, in which two or more pixels are read out from the vertical transfer unit to the horizontal transfer unit during the horizontal blanking period of the video signal. The signal charges added by the horizontal transfer unit are read out by adding two or more pixels in the horizontal direction by the final electrode of the horizontal transfer unit or the signal charge detection unit.

Another mode is a high-resolution or enlargement mode, in which the number of pixels for reading the signal charges of the vertical transfer unit to the horizontal transfer unit during the horizontal blanking period of the video signal with the enlargement area as the center of the element is smaller than in the standard mode. I do. At this time, the signal charges before and after the enlarged area which is not transferred in the vertical effective period of the video signal are read out with the high-speed transfer pulse before and after the vertical blanking period. In the reading of the signal charges in the horizontal transfer unit, the signal charge detection unit can detect the signal charges of a smaller number of pixels than in the standard mode. At this time,
The signal charges before and after the enlarged area that cannot be transferred in the horizontal effective period are read out by overlapping the front and rear by applying a fast horizontal transfer pulse during the horizontal blanking period. A zoom function is realized by appropriately selecting and using these modes.

(Operation) According to the driving method of the solid-state imaging device of the present invention, a novel zoom function different from zoom by arithmetic processing using a special memory and different from optical zoom using a lens is realized.

(Example) Hereinafter, an example of the present invention will be described.

FIG. 1 is a diagram showing an interline transfer type CCD (IT-CCD) image sensor and illustrating a first drive mode according to the present invention.

In the figure, reference numeral 11 denotes a 982 pixel vertical, 1300 horizontal pixel interline transfer CCD image sensor, a photoelectric conversion unit 12 formed in a 1300 × 982 matrix, a vertical CCD 13 provided for each column, It has a horizontal CCD 14, a reset transistor 15, and an output amplifier 16 connected to the respective final ends of the vertical CCD 13. These are integrally formed on a silicon chip.

This element is driven by the four-phase clock pulse φV ₁ , φV ₂ , φV ₃ , φV ₄ for the vertical CCD 13. Horizontal CCD
14 is driven by two-phase clock pulses φH ₁ and φH ₂ , and the final electrode φH ^* is driven independently.

In the first drive mode, the signal charges photoelectrically converted by the photoelectric conversion unit 12 for one field period are vertically transferred in the A field.
Transferred to CCD13. As for the transferred signal charges, signal charges for two pixels SigA1 and SigA2 are transferred to the horizontal CCD 14 during the horizontal blanking period, and are converted into SigA1 + SigA2 signals. The signal charge is read out as SigA3 + SigA4 in the next horizontal blanking period. Thereafter, reading of the entire A field is performed in the same manner. Similar signal reading is performed in the next B field period, but the combination of signal addition is different from the A field in order to increase the vertical resolution by the interlacing operation. For example, during horizontal blanking
Addition of gB2 + SgbB3 is performed and read by the horizontal CCD 14.

The transfer of the horizontal CCD 14 is performed at 24 MHz, and the final electrode φH ^*
Then, the reset electrode RS is driven at 1/2 of 14 MHz. Therefore, charges transferred from the adjacent A field or B field are added by φH ^* . That is, as shown in the figure
The signals SigH ₁ and SigH ₂ transferred at 24 MHz are added at the final electrode to become SigH ₁ + SigH ₂ and output as a voltage by the output amplifier 16. By using this first drive mode, approximately 491 vertical pixels and approximately 650 horizontal pixels can be obtained.
It becomes an image sensor of 320,000 pixels. FIGS. 2 and 3 show timing charts. ΦV ₁ , φV during vertical blanking period
By applying a V _{F S 3,} signal charges are read out of the photoelectric conversion unit 12 to the vertical CCD 13. The signal charge of the vertical CCD 13 is obtained by performing the line shift twice during the horizontal blanking period.
The signal charges for two pixels are transferred to the horizontal CCD 14. In the horizontal effective period of FIG. 3, φH ₁ and φH ₂ are driven at 24 MHz, and φH ^* , R
S is driven at 1/2 its 12 MHz. ΦV ₁ , φV ₂ , φV ₃ and φV ₄ of the vertical CCD 13 perform _two line shift operations during the horizontal blanking period. In FIG. 2, φH ₁ , φH ₂ , φH ^* , R
For simplicity, only sections where signals exist are indicated by hatching. The details of the signals in each section are clear from FIG.

FIG. 4 is a diagram for explaining a second drive mode of this embodiment.

In this mode, only 491 pixels vertically and 650 pixels horizontally are read out during the effective period, and the other high-speed line shift (LS) areas 1 and 2 are read out during the vertical blanking period. Area 2 is read during a horizontal blanking period. The signal charges photoelectrically converted by the photoelectric conversion unit 12 during the vertical blanking period are transferred to the vertical CCD 1
Read to 3. Then, φV ₁ , φV ₂ , φV ₃ , φV ₄ are driven by a high-speed line shift pulse, and 246 of the high-speed LS area 1 is driven.
The signal charges for the pixels are read out by the horizontal CCD. Then, the signal charge of the pixel 491 in the enlarged area is read out during the valid period. In the A field, for example, one pixel of SigA1 is transferred to the horizontal CCD 14 during the horizontal blanking period. In the B field, one pixel of SigB1 is a horizontal CCD during the horizontal blanking period.
Transferred to 14. The signal charge transferred to the horizontal CCD 14 is
First, 325 of the high-speed transfer area 1 within the horizontal blanking period
Pixel signals are read at a high speed of 30 MHz to 60 MHz. This unnecessary charge is appropriately discharged via the reset transistor RS. Next, during the effective period, φH ₁ , φH ₂ , φH ^* , and RS are driven and read out from the 650 pixels in the enlarged area with a horizontal transfer pulse of 12 MHz.
At this time, no horizontal addition is performed. When the enlarged area is read during the valid period, the high-speed horizontal transfer area 2 overlaps with the area 1 and is read while overlapping with the next high-speed horizontal transfer area 1. When 491 pixels of the enlarged area are read during the vertical effective period, the high-speed LS area 2 becomes the same place as the high-speed LS area 1, and the signal charge is read out simultaneously with the next high-speed LS area 1 within the vertical blanking period. By using the second driving method, the center area of the screen can be doubled.
Also, the resolution is about 320,000 pixels of 491 vertical pixels and 650 horizontal pixels,
There is no difference from the first driving method.

FIGS. 5 and 6 show timing charts. .Phi.V ₁ in the vertical blanking period, by applying a V _{F S} in .phi.V _3, reads out the signal charges of the photoelectric conversion unit 12 to the vertical CCD 13. And
The signal charge 246 pixels in which the high-speed LS area 1 and the high-speed LS area 2 one cycle before overlap are continuously subjected to 123 line shifts,
Read by horizontal CCD14. In the horizontal blanking period shown in FIG. 6, first, the line shift operations φV ₁ , φV ₂ , φV ₃ , φV ₄ are set to 1
The signal charge is transferred to the horizontal CCD 14 for one line. Next, the horizontal transfer pulses φH ₁ and φH ₂ are driven at 40 to 60 MHz to read out the signal charges overlapping the high-speed horizontal transfer area 1 + area 2. Next, 650 pixels of the enlarged area are read at 12 MHz.

FIG. 7 shows a second embodiment using an IT-CCD of about 2 million pixels for a high definition (HD) TV. This device has a storage gate BG for one horizontal period at the last electrode of the vertical CCD, and two horizontal CCDs.
A read / horizontal division gate HG is provided.

HD-TV elements have an aspect ratio of vertical: horizontal = 9: 16 and slightly more vertical scanning lines.
982 vertical pixels, 1500 horizontal pixels to achieve an aspect ratio of 3: 4
About 1.5 million pixels are used. The extra 500,000 pixels are vertical
Read during the horizontal blanking period. The signal charges photoelectrically converted by the photoelectric conversion unit 12 in the first drive mode is transferred to the vertical blanking period to the vertical CCD 13, 35 pixels of the high-speed LS area 1 is read is transferred to the horizontal CCD 14 _1, 14 _2.
Signal of the A field in the horizontal blanking period are added by BG gated by line shift twice operation, read after one horizontal period accumulated in the horizontal CCD 14 _1, 14 _2. Then the signal is read by the horizontal CCD 14 _1, 14 ₂ via the BG gate similarly. In the B field, a signal is read in order to perform an interlace operation. The vertical direction is equivalent to 491 pixels obtained by adding two pixels. The transfer of horizontal CCDs 14 ₁ and 14 ₂
After the operation of the line shaft during the horizontal blanking period, the high-speed horizontal transfer area 1 is read at 28 MHz to 60 MHz, and the normal transfer area 1500 pixels are transferred at 14 MHz during the horizontal effective period.
H ^* , φH ₂ ^* , RSA, RSB are driven at 7 MHz, and two pixels in the horizontal direction are added and read by the final electrodes φH ₁ ^* , φH ₂ ^* . The high-speed horizontal transfer area 2 is used for the next horizontal transfer.
And read again.

 FIG. 8 shows a second drive mode of the HD-TV-like element.

In the second drive mode, the enlarged area is vertically 491 pixels, 750 pixels.
Only the pixels are read out during the effective period, and the high-speed LS area 1 and the area 2 are overlapped during the vertical blanking period to read out the high-speed line shift operation. The horizontal transfer pulses φH ₁ and φH ₂ are set to 2
Driving and reading at 8MHz to 60Mhz. Thereafter, the high-speed horizontal transfer area 1 and the area 2 are overlapped during the horizontal blanking period, and 750 pixels of the enlarged area are read at 7 MHz during the horizontal effective period.

 FIG. 9 shows a third embodiment.

In the figure, reference numeral 11 denotes an interline transfer CCD image sensor having 738 vertical pixels and 132 horizontal pixels. The vertical CCD is an image sensor which can perform independent reading of one stage per pixel.

In the first drive mode, signal charges photoelectrically converted by the photoelectric conversion unit 12 are read out to the vertical CCD 13 during a vertical blanking period. The transferred signal charges transfer SigA1, SigA2, and SigA3 to horizontal C during the horizontal blanking period of the A-field cycle.
Transfer to CD14. In the B field period, SigB2, SigB3, and SigB4 are set to horizontal C in order to perform the interlace operation.
Transfer to CD14 and add 3 vertical pixels. Also, horizontal CCD1
Four horizontal pixels are added and read by the final electrode φH ^* of 4. That is, φH ^* and RS are 1/3 of φH ₁ and φH ₂ 24 MHz.
Drive at a frequency of 8 MHz.

FIG. 10 shows an embodiment of a 2 × (2.25 ×) zoom which is the second drive mode. 492 pixels vertically, 868 horizontal
Only the pixels are read out during the valid period, and the 123 pixels in the high-speed LS area 1 and the 123 pixels in the area 2 are overlapped and read out during the vertical blanking period. High-speed horizontal transfer area 1 (217 pixels)
And area 2 (217 pixels) are overlapped and read at 30 to 60 MHz during the horizontal blanking period. The signal charge of the vertical CCD 13 in the enlarged area is SigA in the A field during the horizontal blanking period.
1 and SigA2 are transferred and read as SigA1 + SigA2 by the horizontal CCD 14. In the B field, the data is transferred to and read from the SigB2 and SigB3 horizontal CCDs 14 in order to perform an interlace operation.
The transfer of the horizontal CCD 14 is performed at 16 MHz, and the final electrode φH ^* is
As 8 MHz driving, two pixels in the horizontal direction are added by φH ^* and read. With this drive, a two-fold zoom can be performed.

FIG. 11 shows an embodiment of a 9 × zoom which is the third drive mode. Only the vertical area 246 pixels and the horizontal area 432 pixels are read out during the effective period, and the high-speed LS area 1 (246 pixels) and the area 2 (246 pixels) are read out during the vertical blanking period. Also, high-speed horizontal transfer area 1 (432 pixels) and area 2 (432 pixels) are overlapped and
Read at ~ 60MHz. The signal charge of the vertical CCD 13 in the enlarged area transfers only SigA1 to the horizontal CCD 14 in the A field during the horizontal blanking period. The B field also transfers the same signal SigB1 to the horizontal CCD. Transfer of horizontal CCD14 is 8MHZ
Perform with z. Further, φH ^* and RS of the final electrode are also performed at 8 MHz, and the addition in the horizontal direction is not performed. By this drive, 9
Double zoom can be performed.

While some of the preferred embodiments have been described above, many other embodiments and modifications are possible. Some of them are described below.

In the embodiment, the description has been made of the interline transfer type CCD imaging device. However, the present invention can be applied to a solid-state imaging device having a two-dimensional transfer unit regardless of whether it is a frame transfer type CCD or a stacked type.

In the embodiment, the zoom is set for both the vertical and horizontal directions, and the zoom ratio is the same. However, the zoom may be performed only in the vertical direction, the zoom in the horizontal direction, or the zoom ratio may be changed.

Using an HD-TV element, the aspect ratio can be compressed to 3: 4, and all signals can be output in the NTSC format.

In the embodiment, the data is read in the blanking period except for the enlarged area, but a part of the effective period may be used. At this time,
The signal read during the valid period creates a wide blanking so that no image is displayed on the monitor.

[Effects of the Invention] As described above, by using the driving method of the present invention, a high-performance electronic zoom can be realized in a solid-state imaging device. Therefore, according to the present invention, a high sensitivity mode and a high resolution mode by pixel addition can be selected depending on the subject.
In addition, the image can be enlarged by a zoom lens and further enlarged by an electronic zoom. Further, unlike zooming by image processing, the zooming can be performed in real time, the resolution does not decrease even if zooming is performed, and the zooming can be performed without using a memory or the like by a processing device. Therefore, an inexpensive camera for measurement and monitoring can be obtained. Also, unlike the zoom of the lens, the aspect ratio can be changed only in the desired viewing direction to enlarge the image.

[Brief description of the drawings]

FIG. 1 is a device configuration diagram for explaining a first driving method of the present invention, FIGS. 2 and 3 are timing chart diagrams for explaining a first driving mode, and FIG. FIGS. 5 and 6 are timing charts for explaining the second drive mode, and FIGS. 7 and 8 are diagrams showing the present invention. FIG. FIG. 9, FIG. 10, and FIG. 11 are explanatory views of a third embodiment of the present invention. 11 CCD image sensor, 12 Photoelectric converter 13 Vertical CCD, 14 Horizontal CCD 15 Reset transistor 16 Output amplifier

Claims (2)

(57) [Claims] 1. A photoelectric conversion element formed in a matrix, a plurality of first charge transfer elements for accumulating electric charges formed by the photoelectric conversion elements for each column and transferring the electric charges in a column direction, A second charge transfer element connected to each end of the first charge transfer element for accumulating the transferred charge and transferring the charge in the row direction; and a second charge transfer element connected to the end of the second charge transfer element. A method for driving a solid-state imaging device comprising a device for storing transferred charges and outputting the same as an image signal in two or more types of modes. In the first mode, the first mode is applied to each column. Transfer the charge accumulated in the charge transfer element of a plurality of pixels,
By accumulating the sum of these in the second charge transfer element and sequentially performing column transfer, an image signal for one row is obtained, and this operation is repeated to form an image signal for one sheet. In the mode 2, the electric charge accumulated in the first charge transfer element for each predetermined row of a part of the continuous rows is converted into the length of the entire row and the total continuous column of the photoelectric conversion device. According to the length ratio, image data for one row is obtained by transferring pixels smaller than the plurality of pixels, storing the pixels in the second charge transfer element, and sequentially performing row-direction transfer. Is repeated for the continuous rows to form one image signal. 2. A photoelectric conversion element formed in a matrix, a plurality of first charge transfer elements for accumulating charges formed by the photoelectric conversion elements for each column and transferring the charges in a row direction; A second charge transfer element connected to each end of the first charge transfer element to accumulate the transferred charge and transfer it in the row direction; and a second charge transfer element connected to the end of the second charge transfer element. A method of driving a solid-state imaging device comprising at least two types of modes comprising a device which accumulates transferred electric charges, detects the electric charges, and outputs the same as an image signal, wherein in the first mode, the second electric charge transfer is performed. The charge transfer cycle of the second charge transfer element is an integral multiple of the cycle of the stored charge detection in the output device, so that the charges stored adjacently in the element are detected after being added in the output device. In the second mode, the Method for driving the solid-state imaging device, characterized in that the charge transfer period of the charge transfer device has a small integral multiple than the first mode period of the accumulated charge detection at the output device.