JPH0495478A - Readout system for all-picture element readout type solid-state image pickup element - Google Patents

Abstract

PURPOSE:To secure the positions of upper lines of two horizontal lines which are paired with each other in even fields by transferring the upper horizontal lines paired in the even fields to a vertical register after shifting the horizontal lines by the quantity of two-horizontal lines. CONSTITUTION:Of the two horizontal lines which are paired in even fields, upper lines B0, B1, B2,... are transferred to a vertical register 1 from photodetector elements 2, 2,... as shown in Fig. A. Then signal charges from the photodetecctor elements are shifted downward by the quantity of two lines as shown in Fig. B. When the signals A0, A1, A2, A3,... of untransferred photodetector elements are transferred to the register 1 as shown in Fig. C, the signals are stored in the register 1. When the signals of the even fields are transferred as shown in Fig. A, B, and C and the signals of odd fields are normally transferred, the signals of the photodetector elements 2, 2,... are necessarily outputted to the same circuit system through a horizontal register 3.

Description

[Detailed description of the invention] The present invention will be described in the following order.

A. Industrial field of application B1 Overview of the invention C0 Background art [Figure 3] a. Structure [Figure 3] b. Operation 0 Problem to be solved by the invention [Figure 4] E1 Solving the problem Means for F1 Effect G, Embodiment [Figures 1 and 2] H0 Effects of the invention (A, industrial application field) The present invention provides a readout method for an all-pixel readout solid-state image sensor;
In particular, a large number of light receiving elements arranged in a matrix, a plurality of vertical registers arranged in parallel to vertically transfer signal charges generated in the light receiving elements, and vertical registers arranged in parallel on the output end side of the vertical registers, The present invention relates to a readout method for an all-pixel readout solid-state image sensor that has two horizontal registers that transfer signal charges from the registers in parallel and performs interlaced readout.

(B. Summary of the Invention) The present invention provides a method for outputting signals from the same light-receiving element (pixel) from different output units (horizontal registers) for odd and even fields in the readout method of the above-mentioned all-pixel readout solid-state image sensor. In order to prevent this, in one field, for example an odd field, signals are read out to the vertical register according to the vertical arrangement order of the light receiving elements and vertical transfer is performed, but in the other field, for example an even field, The signal charges on the upper line of the two upper and lower horizontal lines are read out to the vertical register, then the read signal charges are transferred vertically for two lines to the vertical register, and then the signal charges on the lower line are transferred vertically. After reading data into a register, vertical transfer is performed. By doing so, the vertical arrangement order of the signal charges on the two bare horizontal lines is reversed between the light-receiving element and the vertical register. In other words, the signal charges of the same pixel can always be output from the same output section.

(C, Background Art) [Figure 3] In solid-state imaging devices such as COD, signals are generally read out using a field readout method, but to further increase resolution, it is recommended to read out all pixels. There is a need to. In order to read out all pixels, it is necessary to read out two horizontal lines of signals within an IH (horizontal period).

By the way, in order to serially read the signals of two horizontal lines within the IH period, it is conceivable to make the frequency of the horizontal transfer clock pulse that drives the horizontal register twice as high as the conventional one.

However, this is almost impossible, at least in the current situation.

A possible solution would be to provide a plurality of horizontal registers and simultaneously horizontally transfer the signal charges on the odd lines and the signal charges on the even lines using separate horizontal registers.

(a, Configuration) [Fig. 3] Fig. 3 shows such a solid-state image sensor. In the figure, a denotes an image section, which includes a large number of light-receiving elements arranged in a matrix, and a vertical register b provided corresponding to each vertical column of the light-receiving elements to transfer signal charges in the vertical direction. It consists of b,... For convenience, the photodetector is not shown in the figure, and the vertical register b is shown in the image area a.
, b, . . . are shown as if there were only them.

C is a first horizontal register disposed below the image area a, d is a second horizontal register disposed parallel to and spaced from the first horizontal register C toward the bottom of the tank; A control gate disposed between the two horizontal registers C and 6 controls the transfer of signal charges between the first and second horizontal registers c and d. Reference character f denotes a channel stopper arranged at a pitch of one pixel at a position below the control gate e on the surface of the semiconductor substrate, and is shown filled in in the figure.

g is a first output section that takes out the signal charge transferred from the first horizontal register C and outputs it; h is a second output section that takes out the signal charge transferred from the second horizontal register d and outputs it;
This is the output part of Note that i is a first CDS circuit (correlated double sampling circuit) that reduces the noise of the output signal from the first output section g, and j is the first CDS circuit that reduces the noise of the output signal from the second output section. 2 CDS circuit, k is the first AGC that amplifies the signal of the first CDS circuit i, β is the second AGC that amplifies the signal of the second CDS circuit j, m is the signal from AGC k and ρ This is a signal processing circuit that samples each color signal and then generates a luminance signal Y and color difference signals RY and BY.

is transferred to the second horizontal register d. Next, the signal charges of the second line counting from the bottom of the image area a are transferred to the first horizontal register C. Thereafter, the signal charges of the first and second lines are simultaneously transferred by the first and second horizontal registers c and d, and the video signals are simultaneously output from the two output sections g and h to the outside of the solid-state image sensor. These operations are repeated every IH period.

In addition, it has two horizontal registers in this way, and from now on two
Regarding a solid-state imaging device capable of simultaneously outputting two video signals, the results of research have been introduced, for example, in Japanese Patent Laid-Open No. 62-92587.

(b, movement) Next, the operation will be explained.

When the accumulation of signal charges in each light-receiving element is completed, the signal charges of the first line counting from the bottom of the image area a are transferred in parallel to the first horizontal register C, and then to the control gate e.
The first line (D, problem to be solved by the invention) [Fig. 4] By the way, when performing interlaced readout, the conventional solid-state image sensor as shown in Fig.
The signal from the pixel (pixel) is transferred by different horizontal registers c, d in odd and even fields and output from different output parts g, h, and passes through different circuit systems, so the gain and linearity between the two circuit systems are changed. There has been a problem in that horizontal stripes and flicker occur due to the difference in color.

This problem will be explained in detail with reference to FIG. 4 as follows. The figure shows one vertical row of light receiving elements (B
Focusing on the signal charges accumulated in the circuits (OlAOlBl, A1, B2, A2), the flow of the signal charges in odd and even fields is compared and shown.

In odd fields, BO and AO are B1 and A1.
However, B2 and A2 form a pair, and the paired signals are read out simultaneously by two horizontal registers c and d. The upper one of the two horizontal line signals in the pair, AO,
AI, A2, . . . are transferred by the first horizontal register C. In FIG. 4 (and also in FIG. 1), the flow of signals transferred by this first horizontal register C is indicated by thick arrows.

On the other hand, the lower one of the two paired horizontal line signals BO, B1, B2, . . . is transferred by the second horizontal register d. In FIG. 4 (and also in FIG. 1) the flow of signals transferred by this second horizontal register d is indicated by thin arrows. Note that whether the arrows are thick or thin does not indicate a difference in the amount of signal charge or the like.

On the other hand, in the even field, AO and B1 and A1 and B2 form a pair, and the paired signals are read out simultaneously by two horizontal registers c and d. Then, the upper one of the two paired horizontal lines, B1,
B2, . . . are transferred by the first horizontal register C, and the lower ones AO1A1, . . . are transferred by the second horizontal register d.

Therefore, the horizontal register to be transferred to each light receiving element differs depending on whether it is an odd field or an even field. That is, AO, A1. A2, . . . are transferred by the first horizontal register C in odd fields and by the second horizontal register d in even fields.

Further, BOlBl, B2, . . . are transferred by the second horizontal register d in odd-numbered fields, and transferred by the first horizontal register C in even-numbered fields.

In this way, when the same signal is processed by different circuit systems (channels) depending on the field, horizontal stripes, flicker, etc. may occur if there is a difference in gain or linearity between the two circuit systems. Although it is preferable that differences in gain and linearity do not occur, in reality they do occur, and the reality is that it is difficult to avoid horizontal stripes and flicker caused by them. This is a big problem.

In particular, in the case of color solid-state image sensors, the color output from the same output section differs for each field due to most color coding, so if there is a difference in gain or linearity between the two circuit systems, one A phenomenon occurs where even if colors match in one field, the colors do not match in the other field.

Furthermore, since the combination of colors of the signals output from the output sections g and h changes from field to field, it is necessary to provide an appropriate switching circuit between the solid-state image sensor and the color signal processing circuit to switch the signal processing. was there.

The present invention has been made to solve these problems, and it is an 8-power section (horizontal register) in which signals from the same light receiving element (pixel) differ between odd and even fields.
The purpose is to prevent output from.

(E. Means for Solving Problems) The readout method of the all-pixel readout solid-state image sensor of the present invention is as follows:
In order to solve the above problem, in one field, for example an odd field, signals are read out to the vertical register according to the vertical arrangement order of the light receiving elements and vertical transfer is performed, but in the other field, for example an even field, they are paired with each other. The signal charges on the upper line of the two upper and lower horizontal lines are read out to the vertical register, then the read signal charges are transferred vertically for two lines to the vertical register, and then the signal charges on the lower line are transferred vertically. The feature is that vertical transfer is performed after reading to a register.

(F. Effect) According to the readout method of the all-pixel readout solid-state image sensor of the present invention, the signal charge on the upper horizontal line of the two paired horizontal lines in one field is higher than that in the other field. Even though the signal charge of the horizontal line one above is paired with the signal charge of the lower side, the signal charge of the upper horizontal line paired in the other field is read out to the vertical register. The horizontal line is vertically transferred, and then the lower horizontal line is read out to the vertical register, so in the other field, the upper signal charge of the paired horizontal line signals is stored in the vertical register. hold your ground. Of the two paired horizontal line signals in any field, the signal on the upper horizontal line to the right in the vertical register is always transmitted to the lower horizontal line in the vertical register by the upper horizontal register. signals are always transferred by the lower horizontal register. Therefore, it is possible to avoid the problem that signal charges generated in one light receiving element are output from different output sections depending on the field.

(G. Embodiment) [FIGS. 1 and 2] Hereinafter, the readout method of the all-pixel readout solid-state image sensor of the present invention will be described in detail according to the illustrated embodiment.

1 and 2 are explanatory diagrams of one embodiment of the readout method of the all-pixel readout solid-state image sensor of the present invention. FIG. 1 shows the signal flow of odd and even fields, and FIG. ) to (C) show the signal flow of even fields in detail.

As shown in the left part of FIG. 1, in an odd field, the signal charges accumulated in the light receiving elements are read out in the vertical register 1 in the vertical arrangement order of the light receiving elements 2, 2, . . . , and are vertically transferred in that order.

That is, in the odd field, AO and BO, A1 and B1, A2 and B2, A3 and B3 form a pair, and the signals AO1A1, A2, . . . on the horizontal line above each pair are the first horizontal line. Transferred by register 3a, BOlBl,
B2, . . . are transferred by the second horizontal register 3b. The path of the signal transferred by the first horizontal register 3a is the first channel Chl, and the path of the signal transferred by the first horizontal register 3a is the first channel Chl.
The path of the signal transferred by b is the second channel Ch2.
Then, the signals are read out as shown in Table 1 below.

Table 1 H in the table is the horizontal scanning period.

There is no difference from the conventional method for reading out odd-numbered fields.

However, in an even field, as shown in the right part of Figure 1, the lower horizontal line of the paired horizontal lines is read out as is into vertical register 1, but the upper horizontal line is read two horizontal lines lower. The data is shifted to the side, read out to vertical register 1, and then vertically transferred.

That is, in the odd field, B1 and AO form a pair, B2 and A1 form a pair, and B3 and A2 form a pair. Then, shift the upper one of the pair B1, B2, B3, . . . downward by two horizontal lines, and the lower one AO1A1, A2, .
. is read out to vertical register 1 as is. Then, in vertical register 1, AO and B1 become A1
and B2, A2 and B3 become a pair, and AOlAl, A2
, . . . occupy the upper side, and B1, B2, B3, . . . occupy the lower side. Therefore, AOlAl, A2,... are the first
are transferred by the horizontal register 3a of B1, B2, B3.
,... is the second horizontal register 3b! It will be forwarded from here. This is shown in Table 2 below.

Table 2 Therefore, the signals of each light receiving element are transferred by the same horizontal register 3 and processed by the same circuit system (channel) regardless of whether it is an odd field or an even field.

In Figures 2 (A) to (C), the lower horizontal line of the horizontal lines forming a pair in an even field is left as is, but the upper horizontal line is shifted downward by two horizontal lines and placed in vertical register 1. It is a flow chart showing a specific reading method.

First, as shown in FIG.
O, B1, B2, . . . are transferred from the light receiving elements 2.2, . . . to the vertical register 1. The lower side, i.e. AO, A1
．． A2, . . . are not transferred.

Therefore, it is assumed that the solid-state image sensor using this readout method is of a type in which the readout electrode wiring is separated for each horizontal line, that is, separated into odd and even lines so that reading can be performed at different timings. It is necessary as

Next, as shown in FIG. 3B, the signal charge from the light receiving element is shifted downward in the vertical direction by two lines in the vertical register 1.

Next, as shown in FIG. 3C, the untransferred signals AO1A1, A2, A3, . . . of the light receiving elements are transferred to the vertical register l. Then, the signal is stored in the vertical register 1 as shown in the right part of FIG. 1 for an even field.

In this way, for even fields, see Figure 2 (
If the signals are transferred as shown in A) to (C), and the signals are transferred normally for odd fields, each light receiving element 2
．． The signals 2, . . . are always outputted to the same circuit system through the same horizontal register 3 regardless of whether it is an odd field or an even field.

Therefore, in the conventional case, the signal of the same light receiving element differs depending on the field (channels Chi, Ch2 (circuit system)).
It is possible to avoid problems such as horizontal stripes and flicker caused by gain differences and linearity differences between channels. Of course, the colors output from the same output section differ from field to field, and due to differences in gain and reality between channels, there is no possibility that even if a color is present in one field, the color will not match in the other field. Furthermore, since the combination of colors of the signals outputted from the output section differs from field to field, there is no problem of providing a circuit for switching signal processing between the solid-state image sensor and the color signal processing circuit.

(H, Effects of the Invention) As described above, the readout method of the all-pixel readout solid-state image sensor of the present invention allows independent readout of odd-numbered horizontal lines and even-numbered horizontal lines. In one of the odd and even fields, the signal charges from each of the light receiving elements are read out to the vertical register in an order according to the vertical arrangement order of the light receiving elements, and then vertically transferred. , in the other field, the signal charges of the upper line of the two upper and lower horizontal lines that are paired with each other are read out to the vertical register, and then the read signal charges are transferred vertically for two lines to the vertical register, and then The signal charges on the lower line of the two upper and lower horizontal lines that form a pair are read out to the vertical register, and the vertical arrangement order of the signal charges on the two upper and lower horizontal lines that form a pair is determined by the light receiving element and the vertical register. The feature is that the data is reversed at the top of the screen, and then vertical transfer is performed.

Therefore, according to the readout method of the all-pixel readout solid-state image sensor of the present invention, the upper horizontal line of the pair of horizontal lines in one field is the horizontal line one level above it in the other field. Even though the upper horizontal line that is paired in the other field is shifted by two horizontal lines and transferred to the vertical register, in the other field Also maintains the position of the upper horizontal line of the two paired horizontal lines in the vertical register. Of the two paired horizontal lines in each field, the upper horizontal line in the vertical register is always transferred by the upper horizontal register, and the other horizontal line is always transferred by the lower horizontal register.

Therefore, in the conventional case, the signal of the same light receiving element differs depending on the field (channels Chi, Ch2 (circuit system)).
It is possible to avoid problems such as horizontal stripes and flicker caused by gain differences and linearity differences between channels. Of course, the colors output from the same output section differ from field to field, and due to differences in gain and reality between channels, even if the colors match in one field, they will not match in the other field (there is no possibility that this will happen). (
Furthermore, since the combination of colors of the signals outputted from the output section differs from field to field, there is no need to provide a circuit for switching signal processing between the solid-state image sensor and the color signal processing circuit.

[Brief explanation of the drawing]

FIGS. 1 and 2 are for explaining one embodiment of the readout method of the all-pixel readout solid-state image sensor of the present invention.
Figure 1 is a signal flow chart for odd and even fields, Figures 2 (A) to (C) are diagrams showing the signal flow for even fields in detail, and Figure 3 is a schematic diagram of a solid-state image sensor showing the background art. FIG. 4 is a conventional odd field and even field signal flow diagram showing the problem to be solved by the present invention. Explanation of symbols 1... Vertical register, 2... Light receiving element (pixel), 3a, 3b... Horizontal register.

Claims (1)

[Claims] (1) A large number of light receiving elements arranged in a matrix,
A plurality of vertical registers arranged in parallel to vertically transfer signal charges generated in the light receiving element, and two vertical registers arranged in parallel on the output end side of the vertical registers to transfer signal charges from the vertical registers in parallel. In the readout method of the all-pixel readout solid-state image sensor, which has a horizontal register of In one of the even fields, the signal charges from each of the light receiving elements are read out to the vertical register in an order according to the vertical arrangement order of the light receiving elements, and then vertically transferred, and then read out from the other field. Then, the signal charges of the upper line of the two upper and lower horizontal lines that form a pair are read out to the vertical register, and then the read signal charges are transferred to the vertical register for two lines in the vertical direction, and then the two lines are paired with each other. The signal charges on the lower line of the upper and lower horizontal lines are read out to the vertical register, and the upper and lower 2 are paired.
A readout method for an all-pixel readout solid-state image pickup device characterized in that the vertical arrangement order of signal charges of two horizontal lines is reversed between the light receiving element and the vertical register, and then vertical transfer is performed.