JPS5957563A - Solid-state linear image sensor - Google Patents

Abstract

PURPOSE:To eliminate the need for a large capacity of memory, by approaching photoelectric converting elements at an end of each photodetector arranged on a line so as to be an interval below a prescribed distance. CONSTITUTION:Photodiode arrays 36-39 of plural unit photodetectors 32-35 of an image sensor 30 of multi-chip type are arranged on a line on a board 31. Then, a center distance L of unit elements, e.g., a photodiode 36a at the end and a photodiode 37a at the beginning of the elements 32 and 33, at the end where the elements 32-35 are adjacent to each other, is taken as a length being <=3.5 times the pitch P of the photodiode array. Thus, even if there exists any missing of a picture element, it is corrected by using an output signal at the end of both photoelectric converting elements through the constitution above. Then, a sub- image-sensor for compensation is not required and no large capacity memory is required.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to solid state linear image sensors.

In particular, the present invention relates to a so-called multi-dimensional linear image sensor in which a plurality of light-receiving element chips are arranged in a straight line, and is used in copying machines, facsimiles, OCR, and the like.

[Technical background of the invention and its problems]

A solid-state linear image sensor arranges a plurality of photoelectric conversion elements in a straight line, each i-electric conversion element corresponds to one pixel, and reads out the signal charges generated in response to the original using a well-known method. ” to read the image.

FIG. 1 shows an example of a conventional multi-chip image sensor. Reference numeral 1'' indicates an image sensor, in which a plurality of light receiving element chips 3 to 6 are arranged in a straight line on a substrate 2.

The light receiving element chips 3 to G are, for example, COD linear image sensors, and specifically have a length of about 20 to 30 mm. As can be seen from the figure, gaps are created between the photoelectric conversion element arrays 10 to 13 at the ends of adjacent light receiving elements. This is because it is technically difficult to provide the photoelectric conversion element arrays 10 to 13 extending close to the ends of each of the elements 3 to 6. Therefore, in the past, sub-image sensors 7 to 9 were installed 14 to 1 in portions corresponding to each end.
Reference numeral 6 indicates an arrangement of nine electric conversion elements of sub-image sensors 7 to 90.

In the reading operation, when the original sensor 8) is moved in the y direction, the output signals from each of the light receiving elements 3 to 6 and the output signals from the sub image sensors 7 to 9 are stored in memory, and the output signals are integrated as a whole. It forms and outputs two images.

In such a conventional image sensor, since the sub image sensors 7 to 9 must be formed on the same semiconductor substrate, manufacturing becomes complicated and the price becomes high. Furthermore, a large capacity memory is required to compensate for missing pixels and form a complete image, leading to an increase in the number of parts and a complicated configuration. In addition, using a memory requires a lot of signal processing time and has problems in terms of characteristics. [Objective of the Invention] Therefore, the present invention requires adjacent light receiving elements to be placed as close as possible and a memory with a large capacity. The purpose of the present invention is to provide a contact type linear image sensor that does not

[Summary of the invention]

In order to achieve the above object, the image sensor of the present invention has a center distance between the photoelectric conversion elements at the end of each of the linearly arranged light receiving elements, which is set to 3.
The feature is that the points are arranged so that the distance is 5 times or less.

By arranging the pixels in this manner, although pixel loss still occurs at the edge, it can be corrected with optical accuracy using the output signal of the photoelectric conversion element in the vicinity.

〔Effect of the invention〕

According to the configuration of the present invention, even if a pixel is missing, it can be corrected, so there is no need for a sub-image sensor for compensation as in the conventional case, and therefore there is no need for a large-capacity memory. .

In other words, it is sufficient to correct the amount based on the information of the photoelectric conversion elements near the missing pixel. Furthermore, it is C, which reduces memory capacity (as much as possible, reduces processing time and contributes to faster reading speeds).

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to illustrative examples.

First, FIG. 2 shows the structure of a unit light receiving element of the image sensor of the present invention. In FIG. 2, PN junction photodiodes (hereinafter referred to as photodiodes) 22a to 22g, which are photoelectric conversion elements, are arranged linearly on a semiconductor substrate 21, and in the vicinity thereof, a vertical electric charge transfer section and a charge transfer section are arranged. A transfer type shift register is provided. 24 is an output section.

Here, what should be noted is the photodiode array 22a~
22g is provided to extend close to the edge of the semiconductor substrate 21. Regarding this point, in the past, the photodiode array had to be placed inside the end due to the signal charge reading section and the wiring.

Therefore, in the unit light receiving element 20 according to the present invention, the transfer stage pitch of the charge transfer type shift register is made smaller than the pitch of the photodiode arrays 22a to 22g, and the output section 24 and the shift register are moved in the X direction (photodiode array 22a to 22g). On the other hand, photodiode arrays 22a to 22g
are arranged to the very edge, avoiding defective areas near the edges that occur when the wafer is cut 1i, li and divided into chips 21. For example, 4 to 70 mm from the cut end surface of the chip 21.
The transfer stage pitch of each shift register is smaller than each pitch of the photodiode arrays 22a to 22g, and the vertical charge transfer unit 5 transfers the signal charge to compensate for the difference in pitch before shifting. This vertical charge transfer section is provided with channels diagonally so as to connect the photodiode arrays 22a to 22g and the corresponding transfer stage of the shift register B.Although not shown in the drawings, The vertical charge transfer section 5 is provided with transfer electrodes.

By applying a clock ξ pulse to this transfer electrode, the signal charge is transferred to the photodiode array 22 by normal charge transfer operation.
A DC voltage is transferred from a to 22g to the shift register B, or a DC voltage is applied toward the shift register B so that the well of Ili order 'it becomes deeper.

FIG. 3 shows another example of a unit light-receiving element, and the same reference numerals as in FIG. 2 are used for each part. The difference from the one shown in FIG. 2 is that the end of the shift register 23 is bent and an output section 2A is provided at the end. By doing so, it is possible to provide the seven Otodiode single arrays 22a to 22g close to the end of the chip.

Next, FIG. 4 shows an embodiment of a multi-chip image sensor according to the present invention using the unit light receiving elements as described above. In FIG. 4, a multi-chip image sensor 3
0, a plurality of unit light-receiving elements 32 to 35 are arranged on a substrate 31 so that the photodiode arrays 36 to 39 are linearly thin as shown in FIG. 2 or 3.
(X direction). The X direction is the document moving direction. Of course, whether the document moves vertically or the image sensor moves is a problem that differs depending on the application device.

Here, at the ends of adjacent elements of each of the unit light receiving elements 32 to 35, as shown in FIG.
and the beginning i>+! The distance between the centers of the four diodes 37a is set to be 3.5 times or less the pitch P of the photodiode array. This value of 3.5 times indicates the limit for correcting pixel loss caused by the gap between the end photodiode arrays 36a and 37a, as will be described later.

Next, explain the merits t-t=, c (1';-fi,-4
- The digital sensor 30 is used as a so-called fine gradient sensor, and reads an original image using a 1:1 optical system. In that case, the output signals from each of the unit light receiving elements 32 to 35 may be read out simultaneously in parallel, or may be read out for each unit light receiving element.

Now, although the seven photodiode arrays 36 to 39 of each of the unit light receiving elements 32 to 35 are extended to near the ends as shown in FIG. 2 or 3, there is no gap at all. Therefore, in the present invention, the following signal correction is performed.

When the intermediate spacing is 1.5 times or less the pitch P of the photodiodes (hereinafter expressed as L≦1.5P), the end gap, that is, the dead area N, is equal to 1/2 pixel. Since it is below the maximum, it is sufficient to connect the output signals of the unit light receiving elements 32 to 35 as they are. In this case, image distortion due to the loss of 1/2 pixel does not pose a practical problem. The output signal state in this case is expressed as follows.

Photodiodes 36G, 36b, 36a, 37a, 3
The output signals of 7b and 37c are respectively Xl g X2 I X3 tsu X5 X6 ν
When X7, the composite signal is Xl, X2, X3 . It becomes X59X69X7.

Next, in the case of 1.5P≦L≦2.5P, the length of the insensitive part N is approximately one pixel, so the output signal corresponding to this insensitive part N is converted into the adjacent signal X3 or X4. Replace or average value of both X3 and X4 (X3 + X4)/2
Make corrections. In this case, the composite signal is: X1 x29x3gh x4x5. x6 or Xl・X2IX3jX4・X4・X5tsuX6 or X□, X2. X3. (X3+X4)/2. X4. X5.
It becomes X6.

Next, in the case of 2.5P≦L≦3°5P, the length of the non-photosensitive portion N is approximately 2 pixels, so the output signal corresponding to the non-photosensitive portion N is converted to the signal X3. Replace using X4. That is, the composite signal is X□, X2. X3. X3. X4. X4. X5. X6 or XI r X2 + X3+ (X3 +X4)/2
+CX3 +X4)/2.

X4. X5. X6 becomes.

[Modified example]

Although examples of unit light receiving elements are shown in FIGS. 2 and 3, the present invention is not limited thereto.

For example, the image sensor may be a combination of a photodiode and a MOS (MOS) switch circuit in addition to a charge transfer type image sensor. Further, shift register devices may be provided on both sides of the photodiode arrays 22a to 22g.

In the above explanation, an example was shown in which black and white photodiodes were used as photoelectric conversion elements, but for example, one with red, green, and blue needle sensitivity characteristics could be used, and each photodiode could be connected as shown in Figure 6. Even when using image sensors arranged in a repetitive array, the following composite signal can be corrected. In addition, 1.36e, 36h s 36k p
37g s 37J is a photodiode sensitive to red, 36f, 36i, 37e, 371i,
37 is a photodiode sensitive to green, 36g,
36j.

37f and 37i are photodiodes sensitive to blue. Here, the pitch of the three color photodiodes is P
, the distance between the centers of a set of three-color photodiodes at the ends of the connection parts of the unit light-receiving elements 32 and 33 is defined as L (L≦1.5P), (1,5P≦L
≦2.5P) and (2,5P≦L≦3.5P), signal correction can be performed in the same manner as in the six examples described above.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the structure of a conventional multi-chip solid-state near image sensor, and FIG. 2 is a partial view showing the structure of a unit light-receiving element used in the multi-chip solid-state near image sensor according to the present invention. 3 is a partially omitted plan view showing the configuration of another 713-position receiving element; FIG. 4 is a plan view showing an embodiment of the multi-chip solid-state near image sensor according to the present invention. , Fig. 5 is a partially enlarged view showing the connection between the ends of adjacent unit light-receiving elements, and Fig. 6 is a partial enlarged view showing the connection between the ends of unit light-receiving elements using photoelectric conversion elements having minute sensitivity characteristics. FIG. 30...Multi-chip type fixed near image sensor,
31... Substrate, 32-35... Unit light receiving element, 36
~39...7 Otodiode array, 36a,
37a...Photodiode at end, P...Pitch of photodiode, L...Center spacing, N...Insensitive yC section.

Claims (1)

[Claims] 1. A unit photodetector in which photoelectric conversion elements for one pixel that generate signal charges in response to an original are arranged linearly on a semiconductor substrate. It becomes a straight line to 5
A solid-state linear image characterized in that a plurality of photoelectric conversion elements are arranged, and the center distance between the photoelectric conversion elements at the end of each adjacent unit light-receiving element is 3.5 times or less the pitch of each photoelectric conversion element. sensor. 2. In the sensor according to claim 1, the photoelectric conversion element has a predetermined spectral sensitivity characteristic, and the center-to-center spacing is 3.5 times or less than the pitch of the photoelectric conversion element.
Solid-state linear image sensor. 3. A solid-state linear image sensor according to claim 1 or 2, wherein the photoelectric conversion elements have the same spectral sensitivity characteristics. 4. In the sensor according to claim 1, 2, or 3, the center spacing is set to 1.5 times or less of the pitch P of the photoelectric conversion elements, and the output signal of each unit light receiving element is 1. An all-in-one linear image sensor characterized in that a signal is processed as having a 1:1 correspondence with the actual arrangement position of each unit light receiving element. 5.% liver In the sensor according to claim 1 or 3, the center spacing is 1.5 of the pitch P of the photoelectric conversion elements.
The output signal for one pixel missing at the adjacent end of each unit light receiving element is set to 2.5 times to 2.5 times the output signal of the photoelectric conversion element at the end of one adjacent unit light receiving element, or A solid-state linear image sensor characterized in that correction is performed using an average value of output signals of photoelectric conversion elements at the ends of both adjacent unit light receiving elements. 6. In the sensor according to claim 1 or 3, the center spacing is 2.5 of the pitch P of the photoelectric conversion element.
It is set to 3.5 times to 3.5 times, and the signal for two pixels missing at the adjacent end of each unit light receiving element is corrected by the output signal at the end of both adjacent photoelectric conversion elements. Solid-state linear image sensor.