JPH0270181A - Driving system for solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve resolution in a horizontal direction, and to obtain the device of the high resolution by moving a solid-state image pickup chip substrate which is made so that a sampling point gets out of position in a vertical direction between fields relatively in a horizontal direction against an incident optical image. CONSTITUTION:The solid-state image pickup chip substrate is made to vibrate relatively against the incident image in the direction corresponding to horizontality in a reproduced picture in one cycle of one frame period. At that time, a signal charge accumulated in a photodiode in each of A, B fields is moved to a vertical electric charge accumulating device (CCD) during a vertical blanking period, and a moving period and the center of vibration of the solid- state image pickup chip substrate are synchronized. As the result, an effective area for light incidence moves from an opening part shown by a full line to the opening part of a dotted line, and the signal charge due to the light incidence is generated and accumulated at these points. Thus, the number of picture elements in the horizontal direction becomes twice effectively, and the high resolution is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a five-power type solid-state imaging device with high-speed shutter operation.

[Prior art and its problems]

Solid-state imaging devices have many advantages over conventional image pickup tubes, such as being smaller, lighter, more reliable, with no shape distortion, less afterimage, and no shading.
, has begun to be widely used for home video cameras,
Particularly recently, applications are being considered for so-called electronic cameras that do not use silver halide film.

However, conventional solid-state imaging devices are driven to comply with, for example, the NTSC standard system, and therefore, in order to reproduce all the pixels of the solid-state imaging device, the shutter of the Nariko camera must be opened for at least 1/30 seconds. It becomes indispensable. However, if the shutter speed is normally 1/30 second, camera shake will occur unless the image is taken by fixing it on a tripod, for example. Therefore, in order to enable high-speed shutter imaging at 1/30 seconds or less, it is necessary to increase the readout frequency and shorten the time per frame. The readout frequency of the pixel sensor is i, 7.161'vfHz, and even if this could be made to 1432MHz for two, the shutter speed would only be 1/60 seconds at most.On the other hand, the shutter speed of the camera is V up to about 1/1000 second is required, and to satisfy such a high-speed shutter operation, the readout frequency must be 240 MHz, making driving and signal processing of the solid-state imaging device extremely difficult.

For this reason, a platform that attempts to perform a single high-speed shutter image using the conventional method has no choice but to take images without performing interlaced imaging.As a result, the number of pixels is halved in the vertical direction, and the resolution is significantly reduced. descend.

The above matters will be explained in more detail with reference to the drawings.

Figure 1 shows C of the well-known interline transfer method.
This figure shows the grooves of a CD (hereinafter referred to as IT-CCD).

This IT-COD has MX2N photosensitive parts ("l 1 +
"11 rP12 r P;2+ "+3 + "'
+ PIN + PIN + P21 + P21 t
``u,'' 221 ``231''' IP2N, P, 2,・
+ PMl + p,, l ”M2 + ”Mtr
2M3 +...r ”MN 1 ”MN) (hereinafter referred to as P
i, Pi') and this photosensitive area (Pi.

Vertical CCDs (C, C2, . . . CM) for reading out signal charges photoelectrically converted and accumulated by Pi') are arranged alternately in the horizontal direction as shown. and vertical C
The signal charges of the CDs (C4, C2,..., CM) are transferred to the horizontal CCD shift register (1) one stage at a time, and after being transferred within the horizontal CCD shift register (1) during the horizontal effective period, they are sequentially transferred to the output section. 12) Here, the number of vertical transfer stages in the vertical CCD (C8, C2, . . . l''M) is half the number of vertical pixels of the photosensitive section (Pi, Pi').

In the normal television standard system, 1 frame is 2
It consists of fields and performs interlace scanning. Therefore, even IT-CCDs perform imaging operations that are compatible with this. That is, assuming the previous two fields iA and B field, in the A field, two PDs (P12.P+:) and (P1
21 ”+2) l-, (P+s, PIN) + (
P2, +P21)+(P2tr P22) +,”
r ("zN + PtN) + "' r ("
lJ+ + "M+) + (PM21PM2') +
The signal charges accumulated in ``' + (PMN l ``MN) are read out together, and in the B field, the signal charges are spatially 180% perpendicular to the two PDs (Pi, Pi) read out in the A field. Two consecutive PDs with different degree phases (P, LP, □), (P+t, P+s),
−, (P21.P2□), ω22 + “23)
+”'(”)j l'+ PM□) + (P)421
The signal charges accumulated in 2M3) are also read out. Such a signal charge transfer mode is called a field accumulation mode. In this case, since the spatial phases of the signals read out in the A and B fields differ by 180 degrees in the vertical direction, 2NXM sample points are obtained from the entire photosensitive area.

Note that from PD (Pi, Pi) to vertical CCD (C, ·
Signal charge transfer to C2 (CM) is performed by PD and vertical CCD.
Field shift gate (hereinafter referred to as FS) installed between
(referred to as G) (4) is performed by applying pulsed magnetic pressure.

Figure 2 (a) is Figure 1 + 7) IT-CCD is LeF
2(b) shows the signal output waveform, and FIG. 2(c) shows the shutter opening/closing during high-speed shutter. That is, as shown in Fig. 21 (al), the high level bottom pressure VH is applied to the FSG (41). At the same time, the signal charge accumulated in the PD is moved to the vertical COD, and as shown in Fig. 2 (bl) For example, the signal charge accumulated in the A field period is read out from the output section (2) during the B field period.If this signal output is 8 people, the signal charge S generated by the signal charge accumulated in the PD in the B field is output.
B is subsequently read out with a delay of one field period.

As explained in FIG. 1, after all the signal loads accumulated in the A field period in all PDs are moved to the vertical CCD, signal accumulation in the B field is newly performed.

Therefore, in order for the signal output SB in the B field to be degraded as shown in FIG. 2(b), some kind of optical input is required during the B field period.

However, as shown in Figure 2(c), for example, 1/1000
In a high-speed shutter operation in which the optical shutter is opened for only a second and light is input during that time, the A-field signal output SA is obtained, but the B-field signal output SB remains unchanged. This means that 2NXM sample points cannot be obtained from the entire photosensitive area as explained in FIG. 1, but only iNXM sample points can be obtained by high-speed shutter operation.

Therefore, in high-speed shutter operation, the number of pixels in the vertical direction is halved as described above, resulting in a significant drop in resolution.

As mentioned above, even if high-speed shutter operation can be performed using conventional methods without reducing resolution, it can only be done up to 1/60 seconds at most, and if you try to perform shutter operation faster than this, the resolution will drop significantly. Therefore, it cannot be put to practical use.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a driving method for a solid-state imaging device that enables high-speed shutter operation without reducing resolution.

[Summary of the invention]

In the present invention, the opening period of the optical shutter for controlling the passage of the incident light image to the solid-state imaging device is set to two times before and after the operation to simultaneously transfer the signal charges accumulated in the photosensitive part to the readout part, and the opening period is the same. [Effects of the Invention] According to the present invention, signal charges are generated and accumulated in the photosensitive section before and after the signal charge transfer operation to the readout section. Therefore, both signal charges are read out from the output section, and a high-speed shutter operation of about 1/1000 seconds can be easily achieved, which is extremely effective especially for the Naruko camera.

[Embodiments of the invention]

The present invention will be described in detail below using the drawings.

FIG. 1 is a diagram showing an embodiment of the driving method in the solid-state imaging device of the present invention. FIG. 1(a): Narita waveform applied to r'f, field shift gate show.

In other words, the FSG (41
PD (PI
, P+ ) accumulated in the total vertical CCD (C
, , C, , , , , CM).

For example, when obtaining image signals for each field continuously as in a video camera, the above VH application pulse is repeatedly applied for each field, but in the case of a video camera, an instantaneous image is captured. , at least two as shown in FIG. 1 (33). Also, the applied pulse width Ts14
During the signal charge movement period from PD to vertical C'CD, 1μ
~10 μsec.

FIG. 1 (bl indicates the shutter opening period. In this embodiment, as shown in this figure, the shutter is opened only for a period To that spans the high level pressure VH holding period. This period To is, for example, 1/1000 seconds. (1 ms).Here, it is desirable that after the To/2 period after the shutter opens, that is, the center time of the opening period, coincides with the end of the voltage holding period Ts when the alO is at a high level (see FIG. 1). This is because the PD is irradiated with light even during the high-level voltage application period shown in FIG. 1 (al), and the signal 4 generated by this light irradiation flows into the vertical CCD during the high-level voltage application period.

In this way, the terminal of high level voltage vH is centered at fcL,
By opening To/2 before and after that, the signal charge generated and accumulated in the PD during the opening period To/2 in the first half is transferred to the vertical CCD by applying a high level pressure Vo[Iol.
The signal charges generated and accumulated in the FD in the second half opening period To/2 are transferred to the next high pelsi pressure VH (11
By application of 3, it is transferred vertically to CC'D. As a result, both the A field signal SA and the B field signal SB are obtained as signal outputs as shown in FIG. 1(C) l/c.

Here, as mentioned above, since the center of the shutter opening period coincides with the end of the high persi pressure ■H, the A field and the B field
The light irradiation periods in the field are the same, so the levels of the signal outputs SA and SB are almost the same.

By adopting this completely new method of opening the shutter and allowing light to enter over the high-level voltage ■H holding period applied to the FSG, for example,
Even when a high-speed shutter operation of 1000 seconds is required, both A and B' tough-field signals can be output. Therefore, it can be applied to a Shiko camera without reducing the resolution.

It should be noted that the above-mentioned terminal point of the VH application pulse and To
It is desirable to completely match the /2 time points, but since the width Ts of the H application pulse is about 1 μsec, if the shutter opening period To is, for example, 1/1000 seconds (1 msec), Ts is the shutter opening time. It is extremely short, about 0.1% of To. Therefore, there may be some deviation between the end of the VH application pulse and the center of the shutter opening period.

FIG. 4 shows another embodiment of the present invention, and FIG.
) shows the voltage waveform applied to the FSG, FIG. 4(fb) shows the shutter opening period, and FIG. 4(C) shows the signal output.

In the case of this embodiment, as shown in FIG. 4 (bl),
The arrow opening is performed during the period TI of the period To. This period TI is located before and after the vH mark.)0 pulse 00. In other words, the VH application pulse 00 is located within the shutter closing period TM during the period To.

Then, the signal charges generated and accumulated in the PD during the shutter open period 12 of $1 are transferred to the vertical COD by the application of the vH pulse aO, and then generated and accumulated in the PL during the second shirt starter open period t131. The signal 4 load is transferred to the vertical CCD by the stamping port of VH Hals αD. Therefore, the output signal is as shown in Fig. 4 (cl, trillion, SB
You can get both.

According to this embodiment, the shutter closing period TM is provided, and the VH pulse is applied (that is, the signal charge is transferred from the PD to the vertical CCD) within this period. There is no problem with light entering inside.
In addition, the VH pulse application is within the period TM (if it is at the C position,
Therefore, there is an advantage that the allowable range for the time phase shift between the shutter opening and the ■H pulse can be widened.

Here, the shutter speed is defined as the period from the start point of the first shutter opening period qz to the end point of the second shutter period 113 (
Corresponds to To).

In this way, in this embodiment 1j, as in the previous embodiment,
High-speed shutter operation is possible without reducing resolution.

As described above, according to the present invention, high resolution can be achieved with a high speed shutter operation, but the present invention can also be very conveniently applied to a method of improving horizontal resolution, which will be described below.

FIG. 5(a) shows some pixel parts in the IT-CCD shown in FIG.
.

(15-2), (15-3), . . . indicate pixels. As shown in this figure, all of these pixels are not in the effective area for light incidence (C) but in the aperture (1) indicated by the solid line in the figure.
6-1).

Only (16-2), (16-3), etc. are valid areas. The method for improving the horizontal resolution described above focuses on this point and moves the solid-state image sensor chip substrate in a direction corresponding to the horizontal direction on the reproduced image for one frame period relative to the incident image llc. This is a method that vibrates as one period. That is, FIG. 5(b) shows an example of the imaging mode of the solid-state image sensor chip, and according to this example, the chip is moved in the X-axis direction (
(horizontal direction) in a triangular wave pattern. Here, the signal charges accumulated in the PD in each field, A field and B field, are moved to the vertical CCD during an arbitrary period during the vertical blanking period, and during this movement period and the above-mentioned solid-state imaging chip substrate Center of motion (A, B, C in Figure 5(b)
) are synchronized.

As a result, for example, in the A field, the effective area for light incidence is located at the apertures (16-1), (15-2), and (16-3) shown by solid lines in FIG. 5(a). Then, in the B field, these openings are at the positions (17-1) shown by the dotted lines in FIG. 5(a),
(17-2) and (17-3), and signal charges are generated and stored at these positions by light incidence. This is because there are two sample points within one pixel in the horizontal direction, so the effective number of pixels is 2.
This means that it has become @, which means that the horizontal resolution will be doubled.

To apply the present invention to such a system, the method shown in FIG. 6 may be used. That is, FIG. 6(a).

(b) is an FSG that is exactly the same as in Figure 1 (aj, (bl)
Fig. 6(C) shows the applied signal to and the shutter opening period.
shows the above vibration. As is clear from FIG. 6(C), the solid-state imaging chip substrate is vibrated in the horizontal direction so that the center of the shutter opening period To (some deviation is allowable) becomes the center of vibration. In addition, Fig. 6 (dl is Fig. 1 f)
c) is a completely circumferential output signal diagram.

By doing this, it is possible to improve not only the vertical resolution, but also the horizontal resolution by vibrating the solid-state imaging chip board in the horizontal direction, and even during high-speed shutter operation, it is possible to improve the resolution in both the vertical and horizontal directions. resolution is achieved.

In this embodiment, the movement of the solid state and the imaging chip substrate is in the form of a triangular wave, but the movement is in the form of two trapezoidal sine waves.

It may be a stepwise change.

FIG. 7 shows a modification of FIG. 6. Figure 7 (a), (b)
l indicates the applied voltage to the FSG and the shutter opening, respectively, and Fig. 7 (C) indicates the vibration mode. In other words, in the case of Fig. 6, the solid-state imaging chip The board was made to vibrate only while the shutter was open, but in the case of Figure 7, as can be seen from Figure 7(C), the vibration was started before the shutter was opened, and the shutter was closed. This vibration will continue from now on.

In this way, shutter opening can be performed in a state where vibrations are stable, and it becomes easy to match the center of the shutter opening period with the imaging center. Furthermore, even if there is a slight deviation between the center of the shutter opening period and the center of oscillation 1, as shown in Figure 7(d) (the area within the shutter opening period is shown by a solid line, and the rest is shown by a dotted line), , output signal S input and SB
The overlapping of the two apparent spatial intra-pixel sensitivity distributions in each pixel reproduced by this method becomes sharp, resulting in only a slight deterioration in resolution, and does not result in the occurrence of horizontal stripes.

FIG. 8 shows another variation of the cedar shown in FIG. That is, in this method, the solid-state imaging chip substrate is moved in one direction relative to the incident optical image during the above-mentioned shutter opening period.

For example, in the shutter opening period To, pixel (15-1)
.

(15-2), I'15-3)... When the horizontal pitch of the PM1 aperture is LA, and the moving speed of the solid-state imaging board is VB, the imaging board is moved according to the following relationship. The artifact, pixel (1
5-1), (15-2), (15-3)... openings (16-1), (16-2).

At the end of the shutter opening period, (16-3) is moved to a position where it contacts the original opening, as shown by the dotted line in the figure. In this way, there is no need to consider the time phase shift with respect to the shutter opening period in relation to the movement of the imaging chip substrate, so there is no need to worry about the resolution deterioration due to the phase shift described in FIG.

Note that when the shutter speed changes, the above-mentioned VB may be changed accordingly.

FIG. 9 is a diagram showing another row when the present invention is applied to the above-described imaging chip substrate vibration method.

Figure 9 (at, (b) is Figure 4 fa), (b)
FIG. 9 fc) is a diagram showing the vibration mode. That is, as shown in FIG. 9, the Id chip board is made to stand still at the first predetermined position during the first shutter opening period (12), and the chip board is vibrated (moved) during the shutter closing period TM, and the second The shutter opening period (131) is stopped at a second predetermined position. Here, the moving @d is determined by the method of forming two sample points in each pixel as described in FIG. As shown, the movement of the imaging board chip is performed within the shutter closing period TM, but To<TM
As long as is satisfied, the time phase difference 1d between the shutter opening and the chip substrate becomes a problem.

As explained in detail above, the present invention is extremely useful for so-called Shiko cameras, which have recently attracted attention.
D is not limited to −°, and any device may be used as long as the signal load generated in the photosensitive area of each pixel is accumulated for an arbitrary period of time and then transferred to the furnace exit at the same time, such as a light guide filter. The present invention can also be applied to a so-called two-story sensor in which photoelectric conversion is performed and signal charge readout is performed using a conventional solid-state image element. Further, in FIG. 1, a case has been described in which the PDs are arranged in a line in the vertical direction and t is also increased, but the effects of the present invention are not impaired in any way even if a plurality of ■H pulses are printed before and after this.

The present invention can also be applied to a Shiko camera that captures color images using one, two, or three solid-state image chip substrates.
In two- or three-element cameras, images with even higher resolution can be obtained by using the present invention and the pixel shifting method.

Further, in the description of the present invention, a two-dimensional sensor has been described, but high resolution can also be achieved with a one-dimensional sensor.

In addition, the I'I'-CCD in FIG. 1 is shown for the case where the number of PDs in the vertical direction is twice the number of stages of vertical C (?D), but in the present invention, the number of PDs in the vertical direction and the number of stages of vertical CCD are the same. It can also be applied to things.

Further, in the embodiment, a case has been described in which the solid-state imaging chip substrate is relatively moved in a direction corresponding to the horizontal direction on the reproduced image, but it goes without saying that the present invention can also be applied to a case in which the solid-state imaging chip substrate is moved in a diagonal direction (C).

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of an interline transfer type CCD.
FIG. 2 is a diagram for explaining the problems when performing a high-speed shutter operation using the COD shown in FIG. 1, and FIG. 1 is a diagram showing an example of the driving method of the uninvented solid-state imaging device. ,
FIG. 4 is a diagram showing another embodiment of the driving method of the solid-state imaging device of the present invention, and FIGS. 5 to 9 are diagrams for explaining the present invention in detail. PII + Pll * PI3 + Pll + ”
' * PMN + P≦: Photosensitive area CI + "2 *
..., CM: Vertical CC'D (1): Horizontal CCD shift register (2): Output section (4): Field shift gate

Claims (5)

[Claims] (1) It has a photosensitive part arranged one-dimensionally or two-dimensionally on a semiconductor substrate, and the signal charges accumulated after photoelectric conversion in the photosensitive part are simultaneously transferred to a readout part and read out. A solid-state imaging device that performs an operation of accumulating signal charges by light irradiation during a period in which a section is connected to the next, and an optical shutter for irradiating an incident optical image to this solid-state imaging device for an arbitrary period, 1. A driving method for a solid-state imaging device, characterized in that the optical shutter is opened for the same period before and after an operation of simultaneously transferring images to the reading section. (2) The opening period of the optical shutter is provided for the same continuous period before and after the end of the control pulse signal for transferring the signal charge accumulated in the photosensitive section to the readout section. A driving method for a solid-state imaging device according to claim 1. (3) The opening period of the optical shutter is set to the same period before and after the control pulse application period, excluding at least the control pulse application period for transferring the signal charge accumulated in the photosensitive section to the readout section. 2. A driving method for a solid-state imaging device according to claim 1, wherein: (4) The solid-state imaging device moves in a direction corresponding to the horizontal direction on the reproduced image, with the solid-state imaging substrate chip moving around an operation period in which signal charges accumulated in the photosensitive section are simultaneously transferred to the readout section. 2. A driving method for a solid-state imaging device according to claim 1, wherein the solid-state imaging device is moved relative to an incident light image. (5) The solid-state imaging device moves in a direction corresponding to an oblique direction on a reproduced image, with the solid-state imaging substrate chip moving around an operation period in which signal charges accumulated in the photosensitive section are simultaneously transferred to the readout section. 2. A driving method for a solid-state imaging device according to claim 1, wherein the solid-state imaging device is moved relative to an incident light image.