JPH01276875A - One-dimensional image sensor - Google Patents

Abstract

PURPOSE:To reduce the effect of transmission efficiency and to facilitate a layout by possessing a one-dimensionally arranged photoelectric converting element and a reading CCD to read an output value, and alternately arranging the reading CCD on the both sides of the arrangement of the photoelectric converting element. CONSTITUTION:The title image sensor is equipped with NXM pieces of one- dimensionally arranged photoelectric converting elements 1 and M sets of reading CCDs 21-23 to read the output value of the N pieces if photoelectric converting elements 1, and the reading CCD 21-23 are alternately arranged on the both sides of the arrangement of the photoelectric converting elements. The output from the photoelectric converting element 1 is transferred through divided three transfer gates 31, 32 and 33 and the CCD 21, 22 and 23. Thereafter, it is successively transferred through the CCDs 21-23, and read through output amplifiers 41-43. That is, the reading CCD of the one-dimensional image sensor is divided into plural pieces, a transmission distance in the respective CCDs becomes shorter, and the mutual distance between the respective CCDs is made more separate than before. Thus, the effect of the transmission efficiency is reduced, and the layout is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a one-dimensional image sensor (hereinafter referred to as a "linear image sensor") with a small loss in transfer efficiency.

[Conventional technology]

FIG. 3 is a block diagram showing the structure of a conventional linear image sensor. In the figure, l is a photoelectric conversion element such as a photodiode, 2 is a CCD for reading, and 3 is a photoelectric conversion element 1.
A transfer gate 4 controls charge transfer from the CCD 2 to the CCD 2, and 4 is a charge detection amplifier.

Next, the operation will be explained. After photoelectrically converting the optical signal for a certain period of time and accumulating the signal, the signal charge is transferred from the photoelectric conversion element 1 to the CCD 2 through the transfer gate 3. Thereafter, the CCD 2 is operated, and the signal charges are sequentially transferred and outputted from the amplifier 4. The signal charge is repeatedly transferred to the CCD 2 and is transferred to the photoelectric conversion element farthest from the amplifier 4 (
In the photoelectric conversion element 1 (on the right end in FIG. 3), the signal is output after passing through at least a number of transfer stages greater than the number of photoelectric conversion elements.

However, the transfer efficiency of the CCD 2 is finite, and if the transfer efficiency per stage is η, then the overall transfer efficiency ηLot is as follows: η=η8 (1). Here, ·N is the number of transfer stages of the CCD 2.

[Problem to be solved by the invention]

Conventional linear image sensors range from 1ooo to 2000 ([
1i1 photoelectric conversion element, but 5000 to 1000
When integrating 0 photoelectric conversion elements, for example, 10000
Considering the number of photoelectric conversion elements, even if the transfer efficiency per groove is 0.99995, from equation (1), η,. −
], C6 becomes worse. The transfer efficiency of the photoelectric conversion element 1 on the side closer to the amplifier 4 is η, since the number of transfer stages is small. , is almost 1
The transfer efficiency η of the photoelectric conversion element 1 on the right end is close to . ,−
0.61, leading to non-uniformity.

Therefore, in order to reduce the effect on transfer efficiency, conventional
A linear image sensor as shown in FIG. 5 has been proposed.

FIG. 4 shows a configuration in which CCDs 5.6 are arranged on both sides of a photoelectric conversion element 1, and the output value of the photoelectric conversion element 1 is distributed to two CCDs 5.6 for every other pixel and read out. 7 is a transfer gate for transferring signal charges to CCD 6, and 8 is a transfer gate for transferring signal charges to CCD 5. In the case of this configuration, the number of transfer stages is halved, but the transfer distance per one stage groove of C0D5.6 becomes longer, making it difficult to increase the speed. Note that 9.10 is an output amplifier.

FIG. 5 shows a case where the COD from which signal charges are read out is divided into a plurality of pieces. In the same figure, the whole is divided into three parts, and each CC
Read signal charges from DII, 12.13. 14,1
5.16 is an output amplifier.

However, in this configuration, it is difficult to layout the boundaries between C0D11 to C0D13. That is, it is necessary to separate the CCD and layout the electrodes at the portion indicated by A in FIG. 5 at a pitch of one photoelectric conversion element, which is not practical.

The present invention has been made in view of these points, and an object thereof is to obtain a linear image sensor that has less influence on transfer efficiency and is easy to layout.

[Means to solve the problem]

In order to achieve such an object, the present invention includes N×M photoelectric conversion elements arranged in the − dimension, and M sets of readout CCDs for reading output values of the N photoelectric conversion elements. The readout CCDs are arranged alternately on both sides of the array of photoelectric conversion elements.

[Effect]

The readout CCD of the one-dimensional image sensor according to the present invention is divided into a plurality of parts, and the transfer distance in each COD is shortened.
Furthermore, the distances between the CODs are greater than in the past.

〔Example〕

FIG. 1 is a configuration diagram showing an embodiment of a linear image sensor according to the present invention. In the figure, 1 is a photoelectric conversion element arranged linearly, 21, 22, and 23 are readout CCs.
D, 31, 32.33 are transfer gates, 41.4
2.43 is an output amplifier.

In FIG. 1, the output from the photoelectric conversion element 1 is transferred through three divided transfer gates 31, 32.33 and three C0Ds 21, 22.23. after that,
Transferred sequentially through CCDs 21 to 23 and output to output amplifiers 41 to 41.
43. In this embodiment, since the COD is divided and arranged alternately on both sides of the array of photoelectric conversion elements, the layout problem that occurs when dividing is eliminated. Further, since signal charges can be read out simultaneously from a plurality of CODs, signals can be continuously output at high speed.

In the above embodiment, the CCD readout direction is the same direction to the left in the drawing, but the direction may be changed depending on external signal processing. Further, although the case where the number of divisions is three has been described, it may be divided into any number of divisions.

Further, in the example of FIG. 1, the signal charge is transferred to one CCD in each divided block, but it is also conceivable that the signal charge is further divided into a plurality of CCDs and read out, as shown in FIG. Figure 2 shows two parallel CCDs 21a and 21b.
23a, 23b is used to output signals for every other pixel from amplifiers 41a, 41b to 43a, 43b. FIG.

〔Effect of the invention〕

As explained above, the present invention provides N×
Equipped with M photoelectric conversion elements and M sets of readout CODs that read out the output values of the N photoelectric conversion elements, each readout CCD is arranged alternately on both sides of the array of photoelectric conversion elements. The transfer distance in the CCD can be shortened, and each CC
Since the distances D can be made greater than in the past, there is an effect that transfer efficiency is less affected, signals can be read out at high speed, and a one-dimensional image sensor that can be easily laid out can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of a linear image sensor according to the present invention, Fig. 2 is a block diagram showing another embodiment, and Figs. 3 to 5 are block diagrams showing a conventional linear image sensor. It is. ■...Photoelectric conversion element, 21-23...COD, 31
~33...Transfer gate, 41~43...Amplifier.

Claims (1)

[Claims] N×M photoelectric conversion elements arranged one-dimensionally and M sets of reading CCs for reading output values of the N photoelectric conversion elements
D, wherein the readout CCDs are alternately arranged on both sides of the array of photoelectric conversion elements.