JPS6032489A - Solid-state image pickup element - Google Patents

Abstract

PURPOSE:To make sampling pitch of each picture element and blind sector equal simply by setting to make the center of a blind sector and adjoining center of picture element equal distance. CONSTITUTION:In the structure of image pickup section of a solid-state image pickup element, the distance between the centers of image pickup cells PE shown by arrows and the distance between centers of blind sectors US including antiblooming drain ABD are equal T. Signals G (green transmission), R (red transmission), Cy (cyan transmission) and BL (black signal) are transferred respectively to corresponding shift register 30, and read out for each horizontal line in horizontal transfer frequency. Thus, sampling pitch of each picture element and blind sector can be made equal simply. Accordingly, moire caused by phase deviation of sampling is hard to occur when forming luminance signals by signals from picture elements through color separation filters.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a solid-state image sensor, and particularly to a solid-state image sensor having an anti-blooming drain (hereinafter referred to as ABD) in a tM image area.

(Prior Art) In conventional charge transfer type solid-state image sensors, an AB D structure is sometimes provided in order to reduce the influence of excessively moving incident light. In such a case, if one ABD is provided for one horizontal imaging cell, the area occupied by the ABD increases in proportion to the number of horizontal imaging cells, resulting in a very low utilization rate. Therefore, a method is also known in which the above-mentioned drawbacks are eliminated by providing an ABD for each predetermined color phase. However, in this case, there is an ABD with no sensitivity, that is, a dead zone, between the horizontal imaging cells, so when the subject image is spatially sampled with the imaging cells, the sampling interval becomes an unequal pitch of 1, and moiré occurs. This has the disadvantage that it is more likely to occur.

Hereinafter, the above-mentioned drawbacks will be explained by taking a frame transfer type CCD as an example. FIG. 1 is a schematic diagram of a frame transfer type COD, in which 10 is an imaging section, 20 is a part of memory, 60 is a horizontal shift register, and 40 is an output amplifier. Figure 2 (A)
, (B) shows the imaging cell of the imaging unit 10 of the GCD in FIG.
They are a schematic potential diagram near BD and its sensitivity diagram. In the same figure (A), 11 is an anti-pluming barrier (AB), and 12 is an ABD. The shaded areas are photoelectrically converted charges that are temporarily accumulated in each imaging cell. By the way, the sensitivity of the imaging unit has a sensitivity distribution as shown in FIG.
It is located at positions such as I, C2, and 03.

If the pitch Sl, 32.83, of each imaging cell is the same, the distance TI, T2 of the sensitivity center of gravity is the same, but since there is a dead zone US including ABD between T3, T3 > TI = T2. becomes. On the other hand, the number of transfer stages of the horizontal shift register 60 is the same as the number of imaging cells except for the number of empty read stages, and periodic pulses are used for the transfer pulses, so in the end, the spatial sampling phase and signal readout horizontal shift register readout The disadvantage is that moiré occurs when the phases are different.

Conventional methods used for such phase adjustment require very complex clock generators and/or signal separation circuits. Furthermore, even if the original spatial zangling phase can be adjusted, the phase between the projection cells used for the luminance signal is different from the phase that cancels out the sideband signal, resulting in a small amount of aliasing distortion.
It has been difficult to obtain high-resolution luminance signals.

(Objective) The present invention aims to eliminate the drawbacks of the prior art as described above. Another object of the present invention is to provide a solid-state imaging device in which the spatial zangling phase between each imaging cell is substantially the same.

(Example) The present invention will be described in detail below based on Examples.

6(A) and 6(B) are diagrams of the first embodiment of the present invention, FIG. 4 is a signal processing block diagram of the embodiment of FIG. 6, and FIG.
The figure is an explanatory diagram of signal processing timing. In this embodiment, for colorization, green transmission (G), red transmission (R), and green transmission (Cy) filters are provided on each imaging cell PE as a picture element (c color filters (not shown). ), 4
- Charges corresponding to the aforementioned color filters are obtained from the image cell PE, but here they are used as signals G, R, ay
It is called. Further, there is a light shielding layer on ABDJ2, from which a light signal (BL) can be obtained.

The sampling phase of each of the above signals Ct, R, Cy, and BL is shown in Fig. 6 (if the imaging unit structure is such that each angle is 90° like a slope, then there will be a phase difference of 180'' from the signal G on the 01 side). Therefore, it becomes easy to form a luminance signal from the G and Gy signals of the
The horizontal transfer frequency is 10.7MH2, which is 6 times that of C), but if the ABD is also considered to be an imaging cell as in this embodiment, the horizontal transfer frequency is 14.7MH2. FSMH2, which is the same as the master frequency of a general clock generator, which is very convenient.

FIG. 6 (Bl is a diagram showing the structure of the imaging section of the solid-state imaging device of the present invention, in which the centers of each imaging cell PE indicated by arrows and the center 17jl of each dead zone US including ABD are all spaced at equal intervals at T. be.

Signals G, , R, ay and BL obtained from each imaging cell
. is transferred to the corresponding horizontal shift register 60, and read out at a transfer frequency of 14.3 MHz for each horizontal line.

4th. The signal processing method will be briefly explained using FIG.

Thread image section 1 that performs sampling at equal intervals as shown in Fig. 6 (B)
The CCD 5 with 0 is driven by a voltage converting pulse from the clock generator 7 =<6. The G signal 6θ is separated from the GCD output signal 1θ by a sample and hold circuit (S/H) 52 using a command pulse 2e shown in FIG. Similarly KR multiplied signal e, Cy
Signal 5e is separated by S/Hs 51 and 53 by command pulses 7e and 5e shown in FIG. and G signal 6θ
and ay signal 5e are switched by a switch circuit 58 at the timing of G switch pulse 8e and Cy switch pulse 9e shown in FIG. 5, respectively, and output signal 10θ. That is, the signal 10e, the signal Qy, the signal 7, and the signal 16M"tTz are repeated, and the band pass filter 59 passes only the signal of 3.5M[Iz from iMTIz, resulting in a high-frequency luminance signal YH.

In addition, the G and Cy multiplied signals 1 pass through low-pass filters 55 and 56 having passbands of 4J(z) to become color signals G and ay, and by subtracting K, respectively, in a subtracter 57, 5(=cy -G) is obtained.R signal 7θ is also low-pass filter 5
4 and then the color signal R and 11.

As described above? The reflected color signals are comma, white,
The luminance signal, which is converted into color difference signals R-YL and B-YL through a process circuit 60 that performs black processing, matrix processing, etc., is formed from the high-frequency luminance signal Yl-1 and R, G, and B that have been processed. The adder 61 adds the low-band luminance signals YL. If these luminance signal Y and color difference signal are input to an encoder (not shown), NT
SC signals etc. can be formed.

In FIG. 6, the COD shown in FIG. 1 has two horizontal shift registers, a first shift register 61 and a second shift register 62. By using two horizontal shift registers, the horizontal transfer frequency is lowered to facilitate the GCD structure and signal separation.

FIGS. 7(A) and 7(B) are diagrams explaining an embodiment in which the signals from the imaging cells are distributed, and FIG. This is the case where the transfer frequency is increased seven times. The transfer frequency of this method is 7.16M, compared to 1CJ and 7kHz of the conventional method.
Since it is I-Iz, it has the feature that it can be easily formed by simply dividing the frequency of 14.3 MH2 into 2. FIG. 2B shows a case where the horizontal shift registers are driven at different frequencies, and in this case, no register for BL is provided. By doing so, it has a feature that the degree of amplification of the R signal can be increased.

FIG. 8 is a signal processing block diagram in the case of the embodiment of FIG. 7(B). The circuit is simpler than the embodiment shown in FIG. 4, and the YH multiplier signal can be directly obtained from the output SR1 of the first shift register without providing a switch circuit.

To explain the configuration shown in Figure 8, the output signal SRI of the first shift register contains G and Gy signals alternately, so by bandpass filtering this with BPF59 of I MH2-3 and 5MH2, A high frequency i component is obtained.

In addition, a sample hold circuit f? holds the G signal and the Cy multiplied signal alternately. The G signal and Cy multiplied signal are then passed through an LPF55.56 to remove unnecessary high-frequency components.

Also, LPF55! 156 to the subtractor 57
By subtracting, the B signal is obtained.

Also, since only the R signal is output from the output SR2 of the second shift register 32, the unnecessary high-frequency components of the R signal are removed by the LPF 54, and then the signal is input to the process circuit 60 together with the G and B signals. , low-frequency luminance signal YL and color difference 'F3
Obtain R-YL and B-YL. Further, YL and YH are added in an adder 61 to form a composite n-degree signal Y.

(Effects) As mentioned above, the present invention has anti-blooming drain (A
In a solid-state image sensor in which a dead zone including BD is provided at a predetermined period for each picture element, the center of the dead zone and the center of each picture element are set to be equidistant between adjacent picture elements. and the sampling pitch of the dead zone can be made equal very easily.

Therefore, when a luminance signal is formed from signals from each picture element via a color separation filter, moiré due to sampling phase shift is less likely to occur.

FIG. 1 is a schematic diagram of a conventional COD, FIG. 2 is an explanatory diagram of a conventional imaging unit having a flooded anti-blooming drain structure, FIG. 3A is a sampling phase diagram of the first embodiment of the present invention, and FIG. Figure CB) is 8′! COD schematic diagram of 1st example, 4th
The figure is a signal processing block diagram of the first embodiment, FIG. 5 is a signal waveform explanatory diagram of FIG. 4, FIG. 6 is a schematic diagram of the second embodiment of the present invention, and FIGS. 2. Signal distribution to horizontal shift registers is a diagram showing an embodiment of the method, and FIG.
It is a signal processing block diagram of the example of figure (B).

5 is a CCD, 10 is an imaging unit, 50 + 61, 32 is a horizontal shifter, 51, 52, 53 is an assembled circuit, 58 is a switch circuit, US is a dead zone, PE
Imaging cell as a picture element.

Claims (1)

[Claims] (1) A solid-state imaging device in which a dead zone including an overflow drain is periodically provided for each predetermined number of photosensitive picture elements, and the distance between the center of each dead zone and the center of each picture element is set to be equal intervals for adjacent picture elements. 0