KR890006330Y1 - Solid state image scanner - Google Patents

Abstract

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Description

Solid-state imaging device

1 is a circuit diagram showing the configuration of a conventional solid-state imaging device.

2 is a sectional view of a pixel of a conventional solid state image pickup device.

3 is a circuit diagram showing the configuration of a solid-state imaging device of the present invention.

4 is a cross-sectional view of a pixel of the solid-state imaging device of the present invention.

5 is a signal processing circuit diagram used in the solid-state imaging device of the present invention.

* Explanation of symbols for main parts of the drawings

30: element for reset switch 31: horizontal scanning shift register

32: vertical scan shift register 33: interlace

34 photodiode 35 element for vertical switch

36: element for horizontal switch 37: horizontal signal line switch

38: horizontal scan line 38 ': signal line

39: vertical scan line 40: horizontal output line

The present invention relates to a solid-state image pickup device, and more particularly, to a solid-state image pickup device that improves resolution by removing smear noise.

1 is a representative example of a conventional solid state image pickup device, in which 1 is a horizontal scanning shift register for outputting a scanning pulse, 2 is a vertical scanning shift register, and 3 is an interlace circuit 4 is a photodiode arranged in a matrix shape. 5 is a vertical read switch transistor (hereinafter referred to as a vertical switch element) for reading an optical signal accumulated in the photodiode 4, and 6 is a horizontal read switch transistor (hereinafter referred to as a horizontal switch element). 7 denotes a vertical scan line, 8 denotes a vertical output line, 9 denotes a horizontal scan line, 10 denotes a horizontal output line, and 11 denotes an area of an array of photodiodes.

FIG. 2 is a cross-sectional view of the solid-state image sensor shown in FIG. 1 with a P layer 18 on the N-type substrate 19, and a P ⁺ diffusion on the P (18) and N ⁺ on the layers 16 and 17. FIG. The gate insulating film 12 is formed to be insulated from the horizontal output line 10 by being diffused 14 and 15, and the vertical signal line 20 is insulated from the horizontal output line 10 and connected to the N ⁺ diffusion layer 15.

In the conventional solid-state imaging device having the above-described circuit configuration, the photodiode 4 receives light and accumulates photoelectrons in the junction capacitance.

Then, the pulses scanned from the vertical scan shift register 2 conduct the vertical switch elements 5 arranged in a horizontal row connected by the interlace circuit 3 to the vertical scan line 7, and then the horizontal scan shift registers. The scanning pulse output from (1) conducts the horizontal switch element 6 sequentially through the horizontal scanning line 9.

At this time, the photoelectrons accumulated in the photodiode 4 are sequentially outputted to the horizontal output line 10 along the vertical output line 8 to form a video signal.

In the conventional image pickup device, smear noise is generated in proportion to the amount of light emitted from the body, and the cause thereof is light infiltrating into the signal line N ⁺ diffusion layer (14 and 15 in FIG. 2), and photoelectron diffuses in the photodiode. This is because a smear trap mixed by capacitive coupling of the photodiode and the vertical signal line is simultaneously read when the photoelectrons accumulated in the photodiode are read out.

Therefore, the object of the present invention is to remove the smear noise and to obtain a high resolution, to integrate the vertical and horizontal switch elements in each pixel of the image pickup device, and to remove the smear charge in each horizontal blanking period through the reset (Reset) switch Between pixels It is to provide a solid-state imaging device that is arranged to move in the horizontal direction by the length.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a circuit diagram showing a solid-state imaging device of the present invention. The difference from the prior art shown in FIG. 1 is that the array of photodiodes, which are pixels arranged in a row, is arranged in the pixel interval. Move horizontally by the length, that is, horizontally shift the pixels listed in the odd-numbered all-day row or horizontally shift the pixels listed in the even-numbered all-day column, and horizontally output lines of the pixels listed in the all-day column By connecting the reset switching elements 30 to each other, smear noise is removed through the reset switch element 30 operated by the reset pulse R _P every blanking period.

The pixel cross-sectional view of the present invention shown in FIG. 4 shows that the vertical and horizontal switch elements are inscribed in each pixel, so that the gate electrodes 42 and 43 of the vertical and horizontal switches are insulated in the gate insulating film 41. Refrigerated, the accumulated smear noise is removed by the reset switch element.

As described above, the circuit operation for removing the smear charge (or smear noise) will be described in detail. The photodiode 34 receives light emitted from the body and accumulates photoelectrons. The vertical switching element 35 is "on" by this, and the vertical switching element 36 is "on" by the pulse scanned by the horizontal scanning shift register 31.

In the above operation, the vertical and horizontal switching elements of the actual pixels are sequentially switched. In this case, the optical signals accumulated in the photodiode 34 are sequentially input to the signal processing circuit through the horizontal output line 40.

However, the smear charge generated in the circuit diagram of the conventional image pickup device described above is applied to the reset switch element 38 by the reset pulse R _P of the logic " 1 " Are removed accordingly.

Therefore, compared with the conventional solid-state imaging device in which smear noise is accumulated in one frame period As much noise is reduced.

In addition, between the pixels (1, 3, 5…) and the even (2, 4, 6…) rows of the pixels arranged in all-day columns, Since they are arranged by length, the horizontal sampling point is doubled even in the same number of pixels, so that a high horizontal resolution can be obtained.

The optical signal from which the smear charge is removed is input to the signal processing circuit through the horizontal output line (40 in FIG. 3), which is shown in FIG. In FIG. 5, the optical signals Ye, W, and Cy input to the signal processing circuit through the horizontal output line 40 pass through the inverting gates G _{1 to} G _3, respectively, and the inverting gates G ₁ and G _2. ), Respectively, is converted into a luminance signal (-Y) by mixing (mixing) with a signal passing through the inversion gate (G ₃ ) through the delay circuits (D ₁ , D ₂ ), respectively. a circuit (D ₂₎ an optical signal (W) is passed through via an inverting gate (G ₄₎ by mixing with a delay circuit (D ₁₎ the light signal (Ye) is subjected to transform into color signals (B).

The signal passing through the inversion gate G ₄ is converted into a color signal R in addition to the signal passing through the inversion gate G ₃ .

The optical signals Ye, W, and Cy applied to the above-described signal processing circuit diagrams show the relational expressions converted into the luminance signal Y and the color signal RB as follows.

Relation

Y = W + Ye + Cy

= (R + G + B) + (R + G) + (B + G)

= 2R + 2B + 3G... (One)

R = W-CY

= (R + G + B)-(G + B)... (2)

B = W-Ye

= (R + G + B)-(G + R)... (3)

W = R + G + B,

Ye = R + G,

Cy = B + G.

As shown in this relation, the optical signals Ye, W and Cy read out from the photodiodes are converted into luminance signals Y and color signals R and B to become video signals.

As described above, according to the present invention, the smear noise is removed by the reset switch element and the horizontal sampling point is increased to obtain a high resolution.

Claims (1)

In the solid-state image pickup device that constitutes a plurality of pixels arranged dimensionally on the semiconductor substrate 42, each pixel includes a vertical switch device 35, a horizontal switch device 36, and a photodiode 34. Pre-execution or even row of each pixel The vertical switch element 35 is connected to the vertical scan line 39, and the horizontal switch element 36 and the horizontal signal line switch 37 are connected to the horizontal scan line 38. And a reset switch (30) for desmearing the signal lines (38 ') arranged in the vertical direction.