JP2739585B2 - Driving method of solid-state imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal charge reading method for a solid-state imaging device, and more particularly to a high pixel type having a larger number of pixels in the vertical direction than the number of vertical scanning lines in a standard television system. The present invention relates to a signal charge transfer method in a solid-state imaging device.

[Conventional technology]

In order to more clearly capture the subject image, it is important to increase the number of pixels and the pixel density of the solid-state imaging device. For example, when reproducing a subject image in accordance with a commonly used standard television system such as the NTSC system,
In order to sharpen a reproduced image, it is necessary to take an image with a camera equipped with a solid-state imaging device having a pixel density equal to or greater than the number of vertical scanning lines in this system.

Conventionally, based on such a principle, the present applicant has developed a high pixel type solid-state imaging device having a structure shown in FIG.

First, the structure will be described with reference to FIG. 5. Reference numeral 1 denotes a light receiving unit of an inter-line transfer type charge-coupled solid-state imaging device (IT-CCD). 80 arranged in a matrix
0 × 1000 pixels and 800 vertical charge transfer paths adjacent to these vertically arranged pixel groups are formed.

As shown in the drawing, on the surface of each pixel, green stripe filters (G) extending in the horizontal direction are provided in every other row, and the green stripe filters (G) are provided.
Between them, mosaic filters of red (R) and blue (B) are arranged in a completely checkered pattern.

Reference numeral 2 denotes a vertical scanning circuit, which generates a drive signal for transferring signal charges generated in each pixel of the light receiving section 1 in the vertical direction through the vertical charge transfer path.

Reference numeral 3 denotes a horizontal charge transfer path composed of a CCD, which receives the signal charges transferred from the light receiving section 1 line by line and transfers these signal charges horizontally to the output amplifier 4 to output them as serial time-series signals. Let it.

Reference numeral 5 denotes a horizontal scanning circuit which generates a drive signal for the horizontal charge transfer path 3 to transfer the signal charge to the output side at a predetermined timing in synchronization with the transfer timing of the signal charge transferred from the light receiving unit 1. .

Figure 6 shows a portion of a pixel and the vertical charge transfer path provided on the light receiving portion 1, further illustrating the construction of the light receiving unit 1 in detail with reference to the _{drawing, G 11 ~C 15, G 31} ~G ₃₅ , G ₅₁ -G ₅₅ , G ₇₁ -G
₇₅ is a pixel in which a green stripe filter, the pixel group mosaic filters red and blue are provided between these pixels _{B 22, B 24, B 43} , B 45, B 62, B 64 , B ₈₃ , B ₈₅ and R ₂₁ , R
₂₃ , R ₂₅ , R ₄₂ , R ₄₄ , R ₆₁ , R ₆₃ , R ₆₅ , R ₈₂ , and R ₈₄ are arranged in a complete checkered pattern. These vertical charge transfer paths L ₁ ~L ₅ adjacent to the pixel group arranged in the vertical direction of the pixel group is formed. And these on the upper surface of the vertical charge transfer paths L ₁ ~L _5, is formed a plurality of gate electrodes g ₁ to g ₁₇ extending in the horizontal direction so as not to shield the pixels, these gate electrodes vertical scanning Drive signals φ _1A , φ ₂ , φ generated by circuit 2
_{3A, φ 4, φ 1B,} φ 3B is supplied.

These gate electrodes, two have become one set corresponding to each row of pixel groups (for example, a gate electrode g ₁ and g ₂ are pixels G ₁₁ ~G
Corresponding to _15), to transfer the signal charges to the horizontal charge transfer path 3 by generating a charge transfer elements of two on each vertical charge transfer paths L ₁ ~L ₅ for each pixel.

Here, in the sixth FIG transfer gate T of the pixels G ₁₁
It is shown on behalf of the G _11, but transfer gate for on-off control between each pixel and the vertical charge transfer path adjacent to them are formed.

Although not shown, the portion excluding the vertical charge transfer path, the pixel, and the transfer gate is an isolation region.

Then, the pixel groups of two rows are alternately divided into a first field A and a second field B as a set. For example, the first field A is made to correspond to the odd field of the NTSC system, and the second field B is set. Correspond to the even field.

Next, the operation of the solid-state imaging device will be described based on the timing chart of FIG. 7 and the potential profiles of FIGS. 8 and 9.

Figure 7 shows the timing of the drive signal in each field scanning period, first, to describe the operation of the first field scanning period, at time t _1, the driving signals phi _1A, phi _1B
And φ ₂ to “L” level and φ _3A , φ _3B and φ ₄ to “M” level to generate signal charge transfer elements corresponding to the respective drive signals in the vertical charge transfer path. by the "H" level driving signal phi _3A at t _2, pixels corresponding to the gate electrode g _3, g ₁₁ applied driving signal phi _3A (i.e., the red and blue of the first field a filter (A pixel provided with) is turned on to transfer the signal charge of a predetermined pixel to the signal charge transfer element. Then, at time t _3, the driving signals phi _1A,
By setting φ _1B and φ ₂ to “M” level and φ _3A , φ _3B and φ ₄ to “L” level, the potential of the charge transfer element of the vertical charge transfer path is changed, and the signal charge is transferred to the horizontal charge transfer path side. To one element. Next, at time t ₄
In FIG. 8, only the drive signal φ _{1A is set} to “H” level, thereby the pixels (ie, the first field) corresponding to the gate electrodes g ₁ and g ₉ to which the drive signal φ _1A is applied as shown in FIG. A pixel provided with green stripe filter of A)
Is turned on to transfer the signal charge of a predetermined pixel to the signal charge transfer element. The process of transferring the signal charges to the vertical charge transfer path is completed in a period _TVB corresponding to a vertical blanking period of the NTSC system.

Then, from time t ₅ by a drive signal having a waveform as shown is supplied to the gate electrode between times t _6, the horizontal charge transfer path side signal charges according to the pixels of the first field A Forward. Here, the period τ _S in the figure is NTSC
_HB corresponds to one horizontal scanning period (1H) of the system, τ _HB corresponds to a horizontal blanking period, and each drive signal changes within these periods. Then, every time two rows of signal charges are transferred, the two horizontal charge transfer paths 3 repeatedly transfer signal charges to the output terminal side in each horizontal scanning period to repeat the first step.
The signal charges generated in the pixels in the field A are read out.

Next, the signal charges generated in the pixels of the second field B are read. That is, in the period _TVB corresponding to the next vertical blanking period, the drive signal changes similarly to the processing in the first field scanning period. However, FIG. 9 a signal charge by the second to read out the signal charges generated in pixels of the field B, and driving signals phi _3B and phi _1B at time t ₇ and time t ₈ "H" level is transferred to the predetermined charge transfer elements of the vertical charge transfer path next as shown in (Note that Figure 9 shows the case where the driving signals phi _1B at time t ₈ is at the "H" level). Then, at times t _{9 to} t ₁₀ ,
By applying the previous similar timing drive signals between the time t ₅ ~t ₆ of each gate electrode, reads out a signal charge generated in the pixels of the second field B.

As described above, the pixel signals for one frame are read out by performing the first and second field scans.

[Problems to be solved by the invention]

However, in such a conventional method of driving a solid-state imaging device, as shown in FIG. 8, the position of the electric charge when moving from the photodiode to the vertical transfer path is the first position.
In the field, charge phi _1A corresponding to the green, phi ₂ electrodes under red, charge phi _1B corresponding to blue, but existing under phi ₂ electrode, in the second field, electric charge corresponding to green phi
_1B, under phi ₂ electrodes, red, charge corresponding to the blue phi _1A, are present under the phi ₂ electrodes.

Therefore, when two rows of vertical transfer are performed every one horizontal period as in the prior art, the first field and the second
In the field, the output amplifier of the signal corresponding to green and the output amplifier of the signal corresponding to blue and red are switched,
There is a problem that a signal switching circuit is required to connect to an external circuit, and a field flicker occurs due to a difference in output amplifier characteristics.

The present invention has been made in view of such a conventional problem, and provides a signal charge transfer method which does not cause a field flicker while simplifying and miniaturizing an external circuit for processing an output signal. With the goal.

[Means for solving the problem]

In order to achieve such an object, the present invention includes a plurality of pixels arranged in a matrix along the vertical and horizontal directions, and a plurality of vertical charge transfer paths adjacent to a group of pixels arranged in the vertical direction. A green stripe filter extending in the horizontal direction is provided every other row on the surface of each pixel, and a mosaic filter of red (R) and blue (B) is provided between the green stripe filters (G). The filters are arranged in a complete checkerboard pattern, and have a structure in which the first and second fields are alternately set in the vertical direction with one set of two horizontally adjacent pixel groups extending in the horizontal direction. In the charge-coupled solid-state imaging device that performs two rows of vertical transfer during the period, at the time of starting the vertical transfer in each of the fields, the first vertical transfer is performed only in one of the two fields, Output and blue signals corresponding to the colors, the output signals corresponding to red is to be obtained from the same output amplifier in two fields, respectively.

[Operation] In the present invention for reading out signal charges in such a manner, when reading out signal charges for each field scan in the vertical charge transfer path, the order of reading out signal charges in each field scan is made equal. Therefore, it is convenient to process the output signal, and it is possible to output a signal without electric field flicker, which is electrically uniform in each field scan.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

First, a solid-state imaging device to which the present invention is applied is a high-pixel type solid-state imaging device having a structure similar to that shown in FIGS. In other words, the first and second fields are alternately arranged in the vertical direction by using a structure similar to that of the charge coupled solid-state imaging device of the inter line transfer system, and forming a set of two adjacent rows of pixels extending in the horizontal direction. Are set, and on the surface of each pixel, green stripe filters are provided every other row in the vertical direction, and red and blue mosaic filters are arranged in a completely checkered pattern between these green stripe filters. .

Next, a signal charge reading method of the solid-state imaging device having such a structure will be described with reference to the timing charts of FIGS. 1 and 2 and the potential profiles of FIGS. 3 and 4. For convenience of explanation, a case will be described in which the timing drive signal according to the present invention shown in FIG. 1 is applied to the gate electrode of the device shown in FIGS. 5 and 6.

FIG. 1 shows the timing of the drive signal in each field scanning period. First, the operation of the first field scanning period is the same as that of the conventional first field scanning period (FIG. 7). That is, in time t _4, the signal charges and blue signal charges corresponding to the red corresponding to the green in the first field is transferred to the transfer path as shown in Figure 3. Then, from time t ₆ by a drive signal having a waveform as shown until time t ₈ is supplied to the gate electrode, to the horizontal charge transfer path side signal charges according to the pixels of the first field A Forward. Here, a period τ _S in the figure corresponds to one horizontal scanning period (1H) of the NTSC system, τ _HB corresponds to a horizontal blanking period, and each drive signal changes in synchronization with these periods.
More specifically, the waveforms of the drive signals φ _1A , φ _1B , φ ₂ , φ _3A , φ _3B , φ ₄ in each horizontal blanking period τ _HB are rectangular waves having timings as shown in FIG. As shown in the figure, the signal charges can be transferred for two rows by performing the level inversion twice at a predetermined timing for each drive signal.

Each time two rows of signal charges are transferred, two horizontal charge transfer paths 3 transfer the signal charges to the output terminal side in each horizontal scanning period (1H), so that the signals generated in the pixels of the first field A are generated. Read out the charge.

Next, the signal charges generated in the pixels of the second field B are read. That is, in the period _TVB corresponding to the next vertical blanking period, the drive signal changes similarly to the processing in the first field scanning period. However, in order to read out the signal charges generated in the pixels relating to the second field B, the drive signals φ _1B and φ _3B are set to “H” level at times t ₉ and t ₁₀ , respectively, so that the signal charges are shifted to the adjacent vertical direction. The charge is transferred to a predetermined charge transfer element in the charge transfer path. Then, at time t ₁₁ ~t _12, by applying a drive signal having the same timing as the preceding time t ₆ ~t ₉ to the gate electrode,
The signal charges generated in the pixels in the second field B are read. However, in the first horizontal blanking period including the time t _11, unlike the first field scanning time of the time t ₆ ~t _7, the square wave timing as the drive signal shown in FIG. 2 Is performed only once. FIG. 4 shows the potential at this time.

As a result, in the second field scan, the signal charge generated from the pixel provided with the green stripe filter and the signal charge generated from the pixel provided with the red / blue filter are not reversed at the time of reading.

As described above, the pixel signals for one frame are read out by performing the first and second field scans.

As described above, according to this embodiment, as shown in the timing chart of FIG. 1, when the signal charge transferred to the vertical charge transfer path is transferred and read out to the horizontal charge transfer path side, the signal charge of FIG. as indicated differences in time t ₆ and t _11, since the first field scan and the second field scanning transferring first signal charges transferred by shifting one row, the phase of the respective read signal charges each It can be equal in the field scan. That is, for example, in the first field scan, the green signal charges are read out first, and in the second field scan, the red or blue signal charges are read out first. In the connected signal processing circuit, processing for switching the signal read in each field scan is required. In this embodiment, since the signal charges in each field scan are read out in the same phase, an external circuit is used. It can also be simplified. In addition, since each color signal is obtained from the same output amplifier in two fields, it is possible to read out a signal without electric field flicker having uniform electric characteristics in each field.

〔The invention's effect〕

As described above, according to the present invention, the first and second fields are alternately set in the vertical direction as a set of two adjacent rows of pixel groups extending in the horizontal direction. Green stripe filters are provided every other row in the direction, and red and blue mosaic filters are arranged in a completely checkered pattern between these green stripe filters. Two rows of vertical mosaic filters are arranged in one horizontal period. In a charge-coupled solid-state imaging device that performs transfer, at the start of vertical transfer in each field, the first vertical transfer is performed in only one of the fields, and the output of a signal corresponding to green and the output of signals corresponding to blue and red are performed. Since the signal output is obtained from the same output amplifier in each of two fields, a switching circuit for connection to an external circuit for performing signal processing It is possible to suppress the generation of field flicker caused by the difference of when it comes to simultaneously output amplifier characteristics unnecessary.

[Brief description of the drawings]

FIG. 1 is a timing chart showing an embodiment of a signal charge reading system according to the present invention; FIG. 2 is a timing chart showing an enlarged main part in FIG.
3 and 4 are potential profiles at a specific time in FIG. 1; FIG. 5 is a structural explanatory view of a solid-state imaging device to which the present invention is applied; FIG. 6 is a solid-state imaging in FIG. FIG. 7 is an enlarged view of a main part structure showing the structure of a light receiving portion of the device; FIG. 7 is a timing chart showing an example of a conventional driving method; FIGS. It is a potential profile. Symbols in the figure: φ ₂ , φ ₄ , φ _1A , φ _1B , φ _1A , φ _1B ; drive signal 1; light receiving section 2; vertical scanning circuit 3; horizontal charge transfer path 4; output amplifier 5; horizontal scanning circuit g _{1 to} g ₁₇ ; gate electrodes G _{11 to} G ₁₅ , G _{31 to} G ₃₅ , G _{51 to} G ₅₅ , G _{71 to} G ₇₅ ; pixels R ₂₁ , R ₂₃ , R ₂₅ , R ₄₂ provided with a green stripe filter _{, R 44, R 61, R} 63, R 65, R 82, R 84; pixel B ₂₂ provided with the red _{filter, B 24, B 41, B} 43, B 45, B 62, B 64, R 81, R ₈₃ , R ₈₅ ; Pixel with blue filter

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Tetsuo Toma 798 Miyadai, Kaisei-cho, Ashigara-gun, Kanagawa Fuji Photo Film Co., Ltd. (56) References JP-A-62-159994 (JP, A) JP-A-63-141485 (JP, A)

Claims (1)

(57) [Claims] A plurality of pixels arranged in a matrix along the vertical and horizontal directions; and a plurality of vertical charge transfer paths adjacent to a group of pixels arranged in the vertical direction. Has green stripe filters extending in every other row, and mosaic filters of red (R) and blue (B) are arranged in a completely checkered pattern between the green stripe filters (G). And a structure in which the first and second fields are alternately set in the vertical direction by using a set of two rows of pixel groups adjacent to each other extending in the horizontal direction as a set, and perform two-row vertical transfer in one horizontal period. In the method of driving a charge-coupled solid-state imaging device to be performed, at the time of starting vertical transfer in each of the fields, the first vertical transfer is performed only in one of the fields, and a signal corresponding to green is transmitted. Power and blue driving method of the solid-state imaging device, characterized in that output signals corresponding to red is transferred so as to obtain the same output amplifier in two fields, respectively.