JP2004031496A - Linear image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear image sensor that needs no highly accurate mechanical mechanism and enables photographing in high optical resolution and high sensitivity. <P>SOLUTION: The linear image sensor comprises a red diode array 11, a green diode array 12 and a blue diode array 13, and the green diode array 12 positioning between the red diode array 11 and the blue diode array 13 is arranged in a direction of array with a displacement of about a half pitch in a direction of a photodiode array, as illustrated. A signal electric charge detected by the photodiodes R1 to Rn, G1 to Gn and B1 to Bn are read by vertical transfer channels 21a to 2na and 21b to 2nb, and it is transferred in a vertical direction. Then, the electric charge is sent to a horizontal transfer channel 30 through a vertical/horizontal transfer area 40, and furthermore it is sent in a horizontal direction and it is output from an output end OUT. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear image sensor including a photoelectric conversion element array in which photoelectric conversion elements are linearly arranged on a semiconductor substrate, and more particularly to a linear image sensor suitable for color photography including a plurality of photoelectric conversion element arrays.
[0002]
[Prior art]
A linear image sensor used in various devices such as a facsimile, an electronic copying machine, an image scanner, and a barcode reader has an imaging unit formed on a semiconductor substrate. The imaging unit includes a photoelectric conversion element array in which photoelectric conversion elements such as photodiodes are arranged substantially linearly, and a charge transfer unit formed in the vicinity of the photoelectric conversion element array. The charge transfer unit includes a charge transfer channel for transferring a signal charge detected by the photoelectric conversion element, and a plurality of charge transfer electrodes for controlling the signal charge transfer. The signal charge transferred by the charge transfer unit is sent to an output unit such as a floating diffusion amplifier and output as a voltage signal.
[0003]
A linear image sensor for color image capturing has red, green, and blue color filters formed on each photoelectric conversion element, and each photoelectric conversion element has signal charges corresponding to red light, green light, and blue light, respectively. To detect.
[0004]
FIG. 24 shows a schematic configuration of an example of an imaging unit of a conventional linear image sensor for color image imaging. The linear image sensor of FIG. 21 has three rows of photodiode rows 511, 512, and 513 in which substantially rectangular photodiodes 500 are arranged in a straight line. The photodiode rows 511, 512, and 513 include a charge transfer unit 521. 522 and 523 are juxtaposed. Output portions 531, 532, and 533 including floating diffusion amplifiers are formed at one ends of the charge transfer portions 521, 522, and 523, and correspond to signal charges detected by the photodiode 500 from the output terminals 541, 542, and 543. Output voltage.
[0005]
The photodiode rows 511, 512, and 513 output signals corresponding to red light, green light, and blue light, respectively. That is, a red filter (not shown) is formed for each photodiode forming the photodiode array 511, and a green filter (not shown) is formed for each photodiode forming the photodiode array 512, and the photodiode. A blue filter (not shown) is formed on each photodiode forming the column 513.
[0006]
Therefore, since the signals as shown in FIG. 25A are output from the output terminals 541, 542, and 543, after performing AD conversion and other processing, color imaging as shown in FIG. 25B is performed. It can be used as a signal. 25, Rn, G1, G2,..., Gn, B1, B2,..., Bn are the same as R1, R2,..., Rn, G1, G2,. This shows a signal detected by a photodiode provided with Gn, B1, B2,..., Bn, and the same applies to the following description.
[0007]
However, in the linear image sensor of FIG. 24, since it is necessary to provide the charge transfer units 521 and 522 between the photodiode rows 511 and 512 and between the 512 and 513, between the photodiode rows 511, 512, and 513. The interval cannot be reduced. Therefore, in order to perform high-resolution imaging, the direction (hereinafter simply referred to as the sub-scanning direction) intersecting the arrangement direction of the photodiode rows 511, 512, and 513 (hereinafter sometimes simply referred to as the main scanning direction). Position accuracy is required). The accuracy in the sub-scanning direction depends on the mechanical accuracy of the sub-scanning mechanism, and it is generally difficult to obtain a highly accurate mechanism at low cost.
[0008]
FIG. 26 is a diagram illustrating a schematic configuration of another example of an imaging unit of a conventional linear image sensor for imaging a color image. The linear image sensor of FIG. 23 has two rows of photodiode rows 611 and 612 in which substantially rectangular photodiodes 600 are arranged in a straight line. The photodiode rows 611 and 612 are provided close to each other, and the charge transfer units 621 and 622 are provided outside the photodiode rows 611 and 612. In addition, output units 631 and 632 including floating diffusion amplifiers and the like are formed at one ends of the charge transfer units 621 and 622, and voltages corresponding to the signal charges detected by the photodiode 600 are output from the output terminals 641 and 642, respectively. .
[0009]
A red filter and a blue filter (not shown) are alternately formed on each photodiode forming the photodiode row 611, and a green filter (not shown) is formed on each photodiode forming the photodiode row 612. The
[0010]
Therefore, since the signals as shown in FIG. 27A are output from the output terminals 641 and 642, after performing AD conversion and other processing, the calculation of the color signal is performed and FIG. It can be used as a color imaging signal as shown.
[0011]
In the linear image sensor of FIG. 26, since the photodiode rows 611 and 612 are provided close to each other, the mechanical accuracy of the sub-scanning mechanism is not necessarily required. However
H1, H2 Horizontal transfer electrode
Is difficult. That is, if the number of photodiode rows is increased to increase detection sensitivity, the charge transfer unit is arranged in the photodiode row, and the resolution deteriorates.
[0012]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides a linear image sensor capable of high-resolution and high-sensitivity imaging without requiring a high-precision mechanical mechanism.
[0013]
[Means for Solving the Problems]
The linear image sensor of the present invention is a sensor including a plurality of photoelectric conversion element arrays in which a plurality of photoelectric conversion elements are linearly arranged on a semiconductor substrate, and charges from the photoelectric conversion elements are converted into the photoelectric conversion elements. A first charge transfer section that transfers in a direction intersecting the conversion element array direction; a second charge transfer section that transfers charges from the first charge transfer section in the photoelectric conversion element array direction; An output unit that outputs a signal corresponding to the charge transferred by the two charge transfer units, and the photoelectric conversion elements included in the adjacent photoelectric conversion element columns are mutually connected within the photoelectric conversion element column The photoelectric conversion elements are arranged approximately ½ of the pitch between the photoelectric conversion elements and shifted in the photoelectric conversion element array direction, and the first charge transfer unit includes the photoelectric elements included in one or more of the photoelectric conversion element arrays. Corresponding to the conversion element on the semiconductor substrate A first charge transfer channel formed and a plurality of first charge transfer electrodes formed to intersect each of the charge transfer channels in plan view, the first charge transfer channel comprising: It is formed close to the photoelectric conversion elements so as to exhibit a meandering shape extending in a direction intersecting with the photoelectric conversion element array direction as a whole. If comprised in this way, the gap between photoelectric conversion element rows can be made small, and the detection accuracy in the sub-scanning direction substantially orthogonal to the row direction as a whole can be improved. Therefore, even if the allowable range of mechanical sub-scanning accuracy is widened, high-accuracy imaging can be performed.
[0014]
In the linear image sensor of the present invention, the first charge transfer electrode is formed between the photoelectric conversion elements so as to exhibit a meandering shape extending in the photoelectric conversion element array direction as a whole. In this way, the first transfer electrodes corresponding to the photoelectric conversion elements of the plurality of photoelectric conversion element arrays can be formed as one body, and the transfer pulse supply wiring for the transfer electrodes can be easily formed.
[0015]
In the linear image sensor of the present invention, four first charge transfer electrodes are provided corresponding to the photoelectric conversion elements.
[0016]
The photoelectric conversion element array in the linear image sensor of the present invention is composed of photoelectric conversion elements that detect charges corresponding to specific monochromatic light.
[0017]
The photoelectric conversion element rows in the linear image sensor of the present invention are provided in a plurality of rows corresponding to the same monochromatic light. With this configuration, it is possible to improve the resolution in the main scanning direction and increase the detection sensitivity.
[0018]
Further, the photoelectric conversion element arrays corresponding to the monochromatic light in the linear image sensor of the present invention are provided in even columns adjacent to the same monochromatic light. With this configuration, the number of first charge transfer units can be reduced. In addition, since signal charges can be added in the first charge transfer section, the number of stages of the second charge transfer section can be reduced and the detection sensitivity can be increased.
[0019]
Moreover, the monochromatic light in the linear image sensor of the present invention is three types of red light, green light, and blue light.
[0020]
In the linear image sensor of the present invention, the photoelectric conversion element array includes a single-color photoelectric conversion element array including a photoelectric conversion element that detects a charge corresponding to one monochromatic light, and a charge corresponding to each of a plurality of other single-color lights. And a multi-color photoelectric conversion element array composed of photoelectric conversion elements to be detected.
[0021]
In the linear image sensor of the present invention, the single-color photoelectric conversion element array and the multiple-color photoelectric conversion element array are alternately arranged, and the number of the multiple-color photoelectric conversion element arrays is equal to that of the single-color photoelectric conversion element array. More than a number.
[0022]
In the linear image sensor of the present invention, the one single-color light is green light, and the other plurality of single-color lights are red light and blue light, and a photoelectric conversion element for red light and blue light are used. The photoelectric conversion elements are alternately arranged in the column direction.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0024]
(First embodiment)
FIG. 1 shows a schematic configuration of a part of an imaging unit of the linear image sensor according to the first embodiment. The linear image sensor shown in FIG. 1 includes red light detection photodiodes R1, R2,..., Rn−1, Rn (red diode line 11), and green light detection photodiodes G1, G2, respectively. ,..., Gn-1, Gn (green diode row 12), blue light detection photodiodes B1, B2,..., Bn-1, Bn (blue diode row 13). As shown in the drawing, the green diode row 12 positioned between the red diode row 11 and the blue diode row 13 is disposed so as to be shifted in the column direction by about ½ of the pitch in the photodiode row direction.
[0025]
Charges constituting a first charge transfer unit (hereinafter also referred to as “vertical transfer unit”) for transferring signal charges detected by the photodiodes R1 to Rn, G1 to Gn, and B1 to Bn. The transfer channels (hereinafter also referred to as “vertical transfer channels”) 21a to 2na and 21b to 2nb are for transferring in a direction crossing the photodiode column direction. The charge transfer channels 21a to 2na are formed close to the photodiodes R1 and B1, R2 and B2,..., Rn and Bn, respectively, and the charge transfer channels 21b to 2nb are formed close to the photodiodes G1 to Gn, respectively. It has a meandering shape extending in a direction intersecting with the main scanning direction (hereinafter also referred to as “horizontal direction”) (hereinafter also referred to as “vertical direction”). Then, the signal charges read from the corresponding photodiodes at a predetermined timing are transferred to the charge transfer channel (hereinafter sometimes referred to as “horizontal transfer channel”) 30 via the vertical horizontal transfer region 40. To do. The signal charges read to the vertical transfer channels 21a to 2na and 21b to 2nb are predetermined on a first charge transfer electrode (hereinafter also referred to as “vertical transfer electrode”) not shown in FIG. Are transferred in the vertical direction.
[0026]
The second charge transfer channel 30 constitutes a second charge transfer unit together with a second charge transfer electrode (hereinafter also referred to as “horizontal transfer electrode”) not shown in FIG. By supplying a predetermined shift pulse to the second charge transfer electrode, the signal charges detected by the photodiodes R1 to Rn, G1 to Gn, and B1 to Bn are transferred in the main scanning direction. The signal charge is output from the output terminal OUT.
[0027]
The vertical and horizontal transfer region 40 is provided to transfer signal charges from the vertical transfer channels 21a to 2na and 21b to 2nb to the horizontal transfer channel 30. By giving a predetermined shift pulse to a transfer electrode (not shown). Be controlled. This shift pulse has a predetermined relationship with the shift pulse supplied to the vertical transfer electrode and the horizontal transfer electrode, and the signal charges from the photodiodes R1 to Rn, G1 to Gn, and B1 to Bn are transferred horizontally. It is transferred to a predetermined area of the channel 30.
[0028]
Signal charges from the photodiodes R1 to Rn, G1 to Gn, and B1 to Bn are read out to the horizontal transfer channel in a relative positional relationship as shown in FIG. Therefore, signal charges are output from the output terminal OUT in the order of B1, R1, G1, B2, R2, G2, B3,..., Bn, Rn, Gn. These signal charges are converted into voltage signals at an output section (not shown) and output as color signals for each photodiode. Note that the signal charge transfer position in the horizontal transfer channel of FIG. 1 is schematically shown, and there may be a region where some signal charges are not transferred.
[0029]
The output color signal for each photodiode corresponds to each color signal at the detection position as shown in FIG. 2, and the green (G) signal is shifted by about 1/2 pitch, so that it is used as a color image signal. Are corrected to red (R), green (G), and blue (B) signals as shown in FIG. FIG. 3A shows a correction based on the position of the green diode row 12, and the R signal and the B signal are average values of the outputs of two adjacent diodes. FIG. 3 (b) is a correction based on the positions of the red diode row 11 and the blue diode row 13, and the G signal is the average value of the outputs of two adjacent diodes. Although the correction processing here is performed outside the linear image sensor, the correction processing is not limited to the method described here, and other methods may be used.
[0030]
Next, a more detailed configuration of the first and second charge transfer units and a mechanism for reading signal charges to the charge transfer channel and transferring charges to the output terminal will be described. FIG. 4 shows the imaging unit of the linear image sensor of FIG. 1 in more detail, and illustrates vertical transfer electrodes on the vertical transfer channels 21a to 2na and 21b to 2nb, and horizontal transfer electrodes on the horizontal transfer channel. ing. Four charge transfer electrodes V1, V2, V3, and V4 are provided corresponding to one photodiode, and are driven at a timing shifted by a quarter cycle. Some of the charge transfer electrodes V1, V2, V3, and V4 are substantially unnecessary depending on the number of photodiode rows, and some of them are omitted in FIG.
[0031]
In FIG. 4, the vertical transfer electrodes V1 to V4 are schematically shown as single ones corresponding to the respective photodiodes for the vertical transfer channels 21a to 2na and 21b to 2nb. As shown in FIG. 5, the common conductor is used. In FIG. 5, channel stop regions 51, 52, 53, 54, 55, and 56 for separating the photodiodes R1 to Rn, G1 to Gn, and B1 to Bn of the respective colors are formed on the semiconductor substrate on which the photodiodes are formed. The vertical transfer channel 21a is between the channel stop regions 51 and 52, the charge transfer channel 21b is between the channel stop regions 52 and 53, and the charge transfer channel 22a is between the channel stop regions 53 and 54. A vertical transfer channel 22b is formed between the channel stop regions 55 and 56, and a charge transfer channel 223a is formed between the channel stop regions 55 and 56. The vertical transfer electrodes V1 to V4 are formed between the photodiodes so as to exhibit a meandering shape extending in the main scanning direction as a whole.
[0032]
As shown schematically by arrows in FIG. 4 and FIG. 5, the read gate portion that reads signal charges from the photodiode to the vertical transfer channel is the vertical transfer electrode V1 in the red diodes R1 to Rn and the blue diodes B1 to Bn. It is formed between the lower vertical transfer channels 21a to 2na, and in the green diodes G1 to Gn, it is formed between the vertical transfer channels 21b to 2nb below the vertical transfer electrode V3. The read gate electrode is also used as the vertical transfer electrodes V1 and V3, and the signal charge accumulated in the photodiode is transferred to the vertical transfer channels 21a to 21 by supplying a read pulse having a higher potential than the shift pulse to the vertical transfer electrodes V1 and V3. 2na, 21b to 2nb.
[0033]
On the horizontal transfer channel 30, two types of horizontal transfer electrodes H1 and H2 driven at a timing shifted by a half cycle are alternately provided to sequentially transfer and hold signal charges. As schematically shown in FIG. 4, two horizontal transfer electrodes H1 and H2 are formed between the vertical transfer channels. Therefore, two signal charges are transferred and held between each vertical transfer channel. In FIG. 4, regions where signal charges are held are indicated by numbers from 0 to 11 for convenience.
[0034]
The transfer electrodes on the vertical and horizontal transfer regions 40 are not shown, but the signal charges from the vertical transfer channels 21a to 2na and 21b to 2nb are transferred to the holding regions indicated by odd numbers in the horizontal transfer channel 30. Arranged to forward.
[0035]
Next, a signal charge reading operation and a charge transfer operation from the photodiode will be described with reference to a time chart of FIG. As shown in FIG. 6, a four-phase shift pulse shifted by a quarter cycle is applied to the vertical transfer electrodes V1 to V4, and a two-phase shift shifted by a half cycle is applied to the horizontal transfer electrodes H1 and H2. A pulse is applied. Further, a pulse represented by reference sign VH is a shift pulse supplied to the transfer electrode on the vertical and horizontal transfer region 40.
[0036]
At time t1, when the read pulse is superimposed on the shift pulse V3, the signal charges of the photodiodes G1 to Gn are read to the vertical transfer channels 21b to 2nb via the read gate. At time t2, when the read pulse is superimposed on the shift pulse V1, the signal charges of the photodiodes R1 to Rn and B1 to Bn are read to the vertical transfer channels 21a to 2na via the read gate.
[0037]
The signal charges read to the vertical transfer channels 21a to 2na and 21b to 2nb are sequentially transferred and transferred to the horizontal transfer channel 30 at time t3. Accordingly, signal charges as shown in FIG. 7A are held in the respective regions of the horizontal transfer channel 30 at time t3. At time t4, when the shift pulse VH becomes high level again, the signal charge is transferred to the horizontal transfer channel 30 again. At this time, the signal charges transferred at the time t3 are transferred in the horizontal direction by the shift pulses H1 and H2, and each region of the horizontal transfer channel 30 at the time t4 is as shown in FIG. 7B. The signal charge is held.
[0038]
Thereafter, when the shift pulses H1 and H2 are supplied, signal charges are output from the output terminal OUT in the order shown in FIG. Note that “-” in FIG. 7B indicates a portion where there is no signal charge, and the signal in this portion may be ignored during signal processing.
[0039]
As described above, in the linear image sensor according to the first embodiment, a plurality of adjacent diode rows are arranged so as to be shifted from each other by about ½ pitch of the photodiode interval, and the vertical transfer channel is arranged as a whole. Since the arrangement is such that the meandering shape extends in the direction crossing the photodiode column direction, the interval between columns is not widened even if a photodiode column for detecting RGB color signals is provided.
[0040]
(Second Embodiment)
FIG. 8 shows a schematic configuration of a part of the imaging unit of the linear image sensor according to the second embodiment. The linear image sensor of FIG. 8 has a red detection photodiode, a green light detection photodiode, and a blue light detection photodiode arranged in two rows. In FIG. 8, the vertical and horizontal transfer areas and the horizontal transfer channel are not shown.
[0041]
Red light detection photodiodes R1a, R2a,..., Rn-1a, Rna arranged in a row and red light detection photodiodes R1b, R2b,..., Rn-1b, Rnb in a row. The arranged red diode rows 11b are arranged adjacent to each other and shifted in the row direction by about ½ of the pitch in the photodiode row direction. Similarly, green light detection photodiodes G1a, G2a,..., Gn-1a, Gna arranged in a row, and green light detection photodiodes G1b, G2b,..., Gn-1b, Gnb , Bn-1a, Bna are arranged in a row, and blue light detection photodiodes B1b, B2b are arranged in a row. ,..., Bn-1b and Bnb are arranged in a row, and the blue diode row 13b is also arranged adjacently and shifted in the row direction by about ½ of the pitch in the photodiode row direction. Further, the red diode row 11b and the green diode row 12a, and the green diode row 12b and the blue diode row 13a are also arranged so as to be shifted in the column direction by about ½ of the pitch in the photodiode column direction.
[0042]
Vertical transfer channels 21a to 2na, 21b constituting a vertical transfer unit for transferring signal charges detected by the photodiodes R1a to Rna, R1b to Rnb, G1a to Gna, G1b to Gnb, B1a to Bna, B1b to Bnb ˜2nb is transferred in a direction crossing the photodiode column direction. The charge transfer channels 21a to 2na are formed close to the photodiodes R1a and G1a and B1a, R2a and G2a and B2a,..., Rna, Gna and Bna, respectively. G1b and B1b, R2b and G2b and B2b,..., Rnb, Gnb and Bnb are formed close to each other and have a meandering shape extending in the vertical direction.
[0043]
Then, the signal charges read from the corresponding photodiodes at a predetermined timing are transferred to the horizontal transfer channel via a vertical horizontal transfer region (not shown in FIG. 8), transferred in the horizontal direction, and output. In this example, data is read from the vertical transfer channel to the horizontal transfer channel in a relative positional relationship as shown in FIG. Reading in such a relative positional relationship is possible by changing the arrangement density of the horizontal transfer electrodes. It is also necessary to change the number of shift pulses supplied to the vertical transfer electrodes and the transfer electrodes on the vertical and horizontal transfer regions.
[0044]
The output color signal for each photodiode corresponds to each color signal at the detection position as shown in FIG. As is apparent from FIG. 10, the red signals R1a to Rna, the green signals G1a to Gna, and the blue signals B1a to Bna are about the red signals R1b to Rnb, the green signals G1b to Gnb, and the blue signals B1b to Bnb, respectively. Since the pitch is shifted by 1/2 pitch, as shown in FIG. 11, when (R1a, G1a, B1a), (R1b, G1b, B1b), (R2a, G2a, B2a),. The resolution in the scanning direction can be doubled the arrangement pitch of the photodiodes. It is also possible to use by adding as shown in FIG. 12. In this case, the resolution in the main scanning direction is the same as the arrangement pitch of the photodiodes, but the sensitivity is doubled. Can do.
[0045]
(Third embodiment)
FIG. 13 illustrates a schematic configuration of a part of the imaging unit of the linear image sensor according to the third embodiment. The linear image sensor shown in FIG. 13 includes two red diode rows 11a and 11b, two green diode rows 12a and 12b, and two blue diode rows 13a and 13b. This is the same as the second embodiment. In FIG. 13, the vertical and horizontal transfer areas and the horizontal transfer channel are not shown.
[0046]
The difference from the second embodiment is the configuration of the vertical transfer channel. In the linear image sensor of FIG. 13, the vertical transfer channels 21b to 2nb are omitted and the position of the charge readout gate is changed. In the linear image sensor of FIG. 13, as indicated by arrows in FIG. 14, the red diode row 11a, the green diode row 12a, and the blue diode row 13a are located between the vertical transfer channels 21a to 2na below the vertical transfer electrode V1. The red diode row 11b, the green diode row 12b, and the blue diode row 13b are formed between the vertical transfer channels 21a to 2na below the vertical transfer electrode V2.
[0047]
As shown in FIG. 14, the vertical transfer channel 21a is formed between the channel stop regions 57 and 58 formed in the semiconductor substrate on which the photodiode is formed, and the charge reading channels of the photodiodes R1a, G1a, and B1a are charged. The charge readout channels of the photodiodes R1b, G1b, and B1b are formed between the transfer electrode V1 and the charge transfer electrode V2.
[0048]
Since the charge readout channel is provided at a position corresponding to the charge transfer electrodes V1 and V2, a readout pulse having a higher potential than the shift pulse is superimposed on the shift pulses V1 and V2. When such driving is performed, the signal charges of the photodiodes R1a and R1b, G1a and G1b, and B1a and B1b are added and transferred by the vertical transfer channel 21a.
[0049]
Therefore, the color signal for each photodiode that is read and output from the vertical transfer channel to the horizontal transfer channel in the relative positional relationship as shown in FIG. 15 is a highly sensitive color image signal as shown in FIG. Can be used as In addition, since signal addition is performed using signal charges, the number of horizontal transfer units can be reduced, and the amount of signal processing can be reduced.
[0050]
(Fourth embodiment)
In the above embodiment, photodiodes for detecting the same color light are arranged in one row. However, the linear image sensor of the fourth embodiment includes photodiodes for detecting light of different colors in the same column. Composed. FIG. 16 illustrates a schematic configuration of a part of the imaging unit of the linear image sensor according to the fourth embodiment. The linear image sensor shown in FIG. 16 includes red / blue diode arrays in which red light detection photodiodes R1, R2,..., Rn and blue light detection photodiodes B1, B2,. 211 and a green diode row 212 in which photodiodes G1, G2,..., G2n-1 and G2n for detecting green light are arranged in a row. As shown in the figure, the green diode row 212 is arranged so as to be shifted in the row direction by about ½ of the pitch in the photodiode row direction with respect to the red / blue diode row 211.
[0051]
Vertical transfer channels 21a-2 constituting a vertical transfer unit for transferring signal charges detected by the photodiodes R1-Rn, G1-Gn, B1-Bn included in the red / blue diode row 211 and the green diode row 212 (2n) a is formed close to the photodiodes R1 and G1, B1 and G2, R2 and G3,..., Rn and Gn-1, and Bn and G2n, and has a meandering shape extending in the vertical direction.
[0052]
The signal charges read from the corresponding photodiodes at a predetermined timing are transferred to the horizontal transfer channel 30 via the vertical and horizontal transfer region 40, transferred in the horizontal direction, and output. In this example, data is read out to the horizontal transfer channel 30 in a relative positional relationship as shown in FIG.
[0053]
The output color signal for each photodiode corresponds to each color signal at the detection position as shown in FIG. When used as a color image signal, RGB three-color signals are required, so the color signal of the undetected portion is obtained by interpolation as shown in FIG. As is clear from FIG. 18, since the G signal is shifted by about ½ pitch with respect to the R signal and the B signal, correction processing is further performed to obtain an RGB signal as shown in FIG. Such image signal processing is performed outside the linear image sensor. Further, the processing method is not limited to this method.
[0054]
(Fifth embodiment)
FIG. 19 shows a schematic configuration of a part of the imaging unit of the linear image sensor according to the fifth embodiment. The linear image sensor of FIG. 19 includes a red / blue diode row and a green diode row as in the linear image sensor of the fourth embodiment, but differs from the fourth embodiment in that a plurality of rows are provided.
[0055]
The red / blue diode array is a red / blue diode in which red light detection photodiodes R1a, R3a,..., Rn-1a and blue light detection photodiodes B2a, B4a,. .., Bn-1b and red light detection photodiodes R2b, R4b,..., Rnb alternately arranged in one row, red / blue diode row 211b, red , Rn-1c and blue light detection photodiodes B2c, B4c,..., Bnc are alternately arranged in one row, and the red / blue diode row 211c is included. The diode array 211b differs from the red / blue diode arrays 211a and 211c in the arrangement order of the diodes.
[0056]
The green diode array includes green light detection photodiodes G1a, G2a,..., G2n-1a, G2na arranged in a line, and green light detection photodiodes G1b, G2b,. , G2nb are arranged in a row, and a green diode row 212b is included. The green diode row 212a is disposed between the red / blue diode rows 211a and 211b, and the green diode row 212b is disposed between the red / blue diode rows 211b and 211c. Further, the green diode rows 212a and 212b are arranged so as to be shifted in the column direction by about ½ of the pitch in the photodiode row direction with respect to the red / blue diode rows 211a, 211b, and 211c.
[0057]
The vertical transfer channels 21a to 2na constituting the vertical transfer unit for transferring the signal charges detected by the photodiodes included in the red / blue diode rows 211a, 211b and 211c and the green diode rows 212 and 212b are respectively photodiodes. R1a and B1b and R1c, B2a and R2b and B2c,..., Rna, Bnb and Rnc are formed in the vicinity. The vertical transfer channels 21b to 2nb are formed close to the photodiodes G1a and G1b, G2a and G2b,..., Gna and Gnb, respectively, and have a meandering shape extending in the vertical direction.
[0058]
The signal charges read from the corresponding photodiodes at a predetermined timing are transferred to the horizontal transfer channel 30 via the vertical and horizontal transfer region 40, transferred in the horizontal direction, and output. In this example, data is read out to the horizontal transfer channel 30 in a relative positional relationship as shown in FIG.
[0059]
The output color signal for each photodiode corresponds to each color signal at the detection position as shown in FIG. When used as a color image signal, a signal subjected to addition calculation as shown in FIG. 23 is used as a detection color signal. Further, as apparent from FIG. 22, since the G signal is shifted by about ½ pitch with respect to the R signal and the B signal, correction processing is further performed to obtain an RGB signal as shown in FIG. Such image signal processing is performed outside the linear image sensor. Further, the processing method is not limited to this method.
[0060]
Since the linear image sensor of the fifth embodiment uses a signal obtained by adding signal charges of a plurality of photodiodes as a detection color signal, the detection sensitivity can be increased. When compared with the third and fourth embodiments, the sensitivity can be increased by reducing the number of columns. In addition, since the positions of the photodiodes to be added are dispersed, unnatural color signals caused by signal addition can be avoided.
[0061]
【The invention's effect】
As apparent from the above description, according to the present invention, it is possible to provide a linear image sensor capable of high-resolution and high-sensitivity imaging without requiring a high-precision mechanical mechanism.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a part of an imaging unit of a linear image sensor according to a first embodiment.
FIG. 2 is a diagram illustrating a correspondence relationship between an output color signal and a detection position by the linear image sensor according to the first embodiment.
FIG. 3 is a diagram illustrating a color image signal calculated from an output color signal by the linear image sensor according to the first embodiment.
FIG. 4 is a diagram showing a part of the imaging unit of the linear image sensor according to the first embodiment in more detail.
FIG. 5 is a diagram illustrating a configuration example of charge transfer electrodes of the linear image sensor according to the first embodiment.
FIG. 6 is a time chart showing a read operation and a charge transfer operation of the linear image sensor according to the first embodiment.
FIG. 7 is a diagram illustrating a relative position of a signal charge in a horizontal transfer channel of the linear image sensor according to the first embodiment.
FIG. 8 is a diagram illustrating a schematic configuration of a part of an imaging unit of a linear image sensor according to a second embodiment.
FIG. 9 is a diagram illustrating a relative position of a signal charge in a horizontal transfer channel of the linear image sensor according to the second embodiment.
FIG. 10 is a diagram illustrating a correspondence relationship between an output color signal and a detection position by the linear image sensor according to the second embodiment.
FIG. 11 is a diagram illustrating an example of a color image signal obtained from an output color signal by the linear image sensor according to the second embodiment.
FIG. 12 is a diagram showing another example of a color image signal obtained from an output color signal by the linear image sensor according to the second embodiment.
FIG. 13 is a diagram illustrating a schematic configuration of a part of an imaging unit of a linear image sensor according to a third embodiment.
FIG. 14 is a diagram showing in detail a part of the imaging unit of the linear image sensor according to the third embodiment.
FIG. 15 is a diagram illustrating a relative position of signal charges in a horizontal transfer channel of the linear image sensor according to the third embodiment;
FIG. 16 is a diagram showing a schematic configuration of a part of an imaging unit of a linear image sensor according to a fourth embodiment.
FIG. 17 is a diagram illustrating a correspondence relationship between an output color signal and a detection position by the linear image sensor according to the fourth embodiment.
FIG. 18 is a diagram illustrating an example of a color image signal calculated from an output color signal by the linear image sensor according to the fourth embodiment.
FIG. 19 is a diagram showing a schematic configuration of a part of an imaging unit of a linear image sensor according to a fifth embodiment.
FIG. 20 is a diagram illustrating an example of a relative position of a signal charge in a horizontal transfer channel of the linear image sensor according to the fourth embodiment.
FIG. 21 is a diagram illustrating another example of the relative position of the signal charge in the horizontal transfer channel of the linear image sensor according to the fourth embodiment.
FIG. 22 is a diagram illustrating a correspondence relationship between an output color signal and a detection position by the linear image sensor according to the fourth embodiment.
FIG. 23 is a diagram illustrating an example of a color image signal calculated from an output color signal by the linear image sensor according to the fifth embodiment.
FIG. 24 is a diagram showing a schematic configuration of an example of a conventional linear image sensor.
25 is a view showing an output signal of the linear image sensor in FIG. 24. FIG.
FIG. 26 is a diagram showing a schematic configuration of another example of a conventional linear image sensor.
27 is a view showing an output signal of the linear image sensor of FIG.
[Explanation of symbols]
11, 11a, 11b ... red diode array
12, 12a, 12b ... green diode array
13, 13a, 13b ... Blue diode array
21a to 2na, 21b to 2nb, 21 to 23, 21a to 23c ... charge transfer channel (vertical transfer channel)
30 ... Charge transfer channel (horizontal transfer channel)
40 ... vertical and horizontal transfer area
OUT ... Output terminal
51-58 ... Channel stop region
V1 to V4 ... Vertical transfer electrodes
H1, H2 Horizontal transfer electrode
211, 211a to 211c: Red / blue diode array
212, 212a to 212c ... Green diode array
500, 600... Photodiode
511-513,611,612 ... Photodiode row
521 to 523, 621, 622... Charge transfer unit
531 to 533, 631, 632... Output unit
541-543, 641, 642... Output terminal

Claims (10)

A linear image sensor including a plurality of photoelectric conversion element arrays in which a plurality of photoelectric conversion elements are linearly arranged on a semiconductor substrate,
A first charge transfer unit that transfers charges from the photoelectric conversion elements in a direction crossing the photoelectric conversion element row direction;
A second charge transfer unit configured to transfer charges from the first charge transfer unit in the photoelectric conversion element array direction;
An output unit that outputs a signal corresponding to the charge transferred by the second charge transfer unit;
The photoelectric conversion elements included in the adjacent photoelectric conversion element arrays are arranged so as to be shifted from each other in the photoelectric conversion element array direction by about ½ of the pitch between the photoelectric conversion elements in the photoelectric conversion element array. And
The first charge transfer unit includes a first charge transfer channel formed on the semiconductor substrate corresponding to the photoelectric conversion element included in one or a plurality of the photoelectric conversion element arrays, and each of the charge transfer channels. A plurality of first charge transfer electrodes formed so as to intersect with each other in plan view,
The linear image sensor, wherein the first charge transfer channel is formed close to the photoelectric conversion element so as to exhibit a meandering shape extending in a direction intersecting with the photoelectric conversion element array direction as a whole. The linear image sensor according to claim 1,
The linear image sensor formed between the photoelectric conversion elements so that the first charge transfer electrode as a whole has a meandering shape extending in the photoelectric conversion element array direction. The linear image sensor according to claim 1 or 2,
Each of the first charge transfer electrodes is a linear image sensor provided with four corresponding to the photoelectric conversion elements. The linear image sensor according to any one of claims 1 to 3,
Each of the photoelectric conversion element arrays is a linear image sensor including photoelectric conversion elements that detect charges corresponding to specific monochromatic light. The linear image sensor according to claim 4,
The said photoelectric conversion element row | line | column is a linear image sensor provided in multiple rows | lines corresponding to the same monochromatic light. The linear image sensor according to claim 5,
The photoelectric conversion element array corresponding to the monochromatic light is a linear image sensor provided with an even number of columns adjacent to each other for the same monochromatic light. The linear image sensor according to any one of claims 4 to 6,
The monochromatic light is a linear image sensor having three types of red light, green light, and blue light. The linear image sensor according to any one of claims 1 to 3,
The photoelectric conversion element array includes a single-color photoelectric conversion element array that includes a photoelectric conversion element that detects a charge corresponding to one monochromatic light, and a photoelectric conversion element that detects a charge corresponding to each of a plurality of other monochromatic lights. A linear image sensor including a multi-color photoelectric conversion element array. The linear image sensor according to claim 8,
The single-color photoelectric conversion element array and the multiple-color photoelectric conversion element array are alternately arranged,
A linear image sensor in which the number of the multi-color photoelectric conversion element arrays is larger than the number of the single-color photoelectric conversion element arrays. The linear image sensor according to claim 8 or 9, wherein
The one monochromatic light is green light,
The other plurality of monochromatic lights are red light and blue light, and the photoelectric conversion elements for red light and the photoelectric conversion elements for blue light are alternately arranged in the column direction.

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