JP2000205945A - Infrared line sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared line sensor without a dead area. SOLUTION: Two lines 1A, 2A of infrared detection elements arranged at predetermined intervals to one another are aligned parallel to each other and an interval of the same size as the infrared detection 12 of each infrared detection element is region formed between the infrared detection regions 12 of each adjacent pair of infrared detection elements, with the detection regions of the other line located in the intervals. A delay circuit 21 is connected to each infrared detection element of the line 2A. The delay circuit corrects the offset of output signals by means of a correction time calculated on the basis of the center distance L between the lines 1A, 2A and scanning speed. Therefore, detection signals of the leading line 2A are outputted at the same timing as signals outputted from the line 1A, and signal outputs with no time difference are made possible. Also, the scanning regions 20' of the infrared detection elements are in close contact with one another, forming scanning regions with no dead areas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared line sensor constituted by arranging a plurality of infrared detecting elements.

[0002]

2. Description of the Related Art As an infrared line sensor, for example, a sensor configured by arranging thermal infrared detecting elements in a line is used. However, in such a configuration, a non-detection area is formed between detection areas of adjacent infrared detection elements.
This is for the following reason.

FIGS. 7 and 8 show the structure of a thermal infrared detecting element. FIG. 7 is a top view, and FIG.
It is an enlarged view of -A section. A diaphragm 3 having low thermal conductivity is formed on a semiconductor substrate 1. Eight sets of p-type semiconductors 4 and n-type semiconductors 5 serving as thermopiles are arranged on the diaphragm 3 in a cross shape by arranging two sets each having a band-like pattern. From a set of n-type semiconductors and p-type semiconductors connected to output terminals 9 and 10 on the side B of the semiconductor substrate, adjacent n-type semiconductors and p-type semiconductors are sequentially connected by metal electrodes 7 and 8. . The inner metal electrode 7 is a hot junction and the outer metal electrode 8 is a cold junction.

[0004] Since the infrared detection signal is proportional to the temperature difference between the hot junction and the cold junction, it is etched from the etching hole 6 so as to improve the thermal separation between the hot junction and the cold junction. Except for removing a part of the semiconductor substrate, a cavity 2 for separating the diaphragm from the semiconductor substrate is formed. An infrared absorbing portion 26 that absorbs infrared light is formed smaller than the cavity 2 so as to cover the hot junction formed by the metal electrode 7 with the insulating layers 11 and 17 interposed therebetween. In FIG. 7, in order to show the structure of the thermopile, the infrared absorbing portion 26 is taken and its position is shown by a virtual line. As described above, the thermal type infrared detecting element has a cavity for heat separation structurally, and the infrared absorbing section for absorbing infrared light is provided in the cavity area, so that the area occupied by the infrared absorbing section is the detection area. , Its surrounding area becomes a non-detection area.

[0005]

Therefore, in the infrared line sensor in which the thermal infrared detecting elements are arranged in a line with the detecting surfaces having infrared absorbing portions aligned on the same surface,
As shown in FIG. 9A, a non-detection area X formed by the peripheral area 27 between the detection areas 12 of the adjacent infrared detection elements 20 is formed on the infrared detection surface.

When the infrared line sensor detects infrared rays by scanning in a scanning direction perpendicular to the column, the scanning area corresponds to the detection area 12 of each infrared detection element as shown in FIG. An output signal is obtained only from the scanned area 20 ', and a dead area D where no output signal is obtained between the scan areas 20' due to the non-detection area. Due to the generation of the dead area, infrared rays are not detected during the dead area. Therefore, the detectable area (detection area) in a predetermined area is limited, and there is a problem that the detection sensitivity cannot be improved. The present invention has been made in view of the above conventional problems,
It is intended to provide an infrared line sensor having no dead area.

[0007]

According to the present invention, a plurality of infrared detecting element rows in which a plurality of infrared detecting elements having a detecting area shorter than the element length are arranged are provided in parallel, When the detection element rows are viewed from the scanning direction, each infrared detection element row is shifted so that the detection area of another infrared detection element row is located in the non-detection area between the infrared detection elements in each infrared detection element row. It was arranged.

In the invention according to claim 2, the number of infrared detecting element rows is set according to the size of the non-detection area and the detection area of the infrared detecting element row, and the infrared detecting element rows are sequentially shifted. It was taken.

According to a third aspect of the present invention, the intervals between the infrared detecting elements in each infrared detecting element row are set so that the detection areas of the respective infrared detecting element rows do not overlap when viewed from the scanning direction. did.

According to a fourth aspect of the present invention, a diaphragm having low thermal conductivity is provided on the surface of the semiconductor substrate, and a plurality of infrared absorbing sections are arranged at predetermined intervals on the surface of the diaphragm. When viewed from a scanning direction perpendicular to the row, the infrared absorption sections of the other infrared absorption section rows are located in the non-detection areas between the infrared absorption sections in each infrared absorption section row, and the adjacent infrared absorption sections Are set so that opposing sides thereof are on the same straight line, and a cavity is formed in the semiconductor substrate under the diaphragm so as to include the array of infrared absorbing parts. Hot junction, a thermopile having a cold junction located on the peripheral side other than the cavity is formed in the scanning direction, and a through-hole penetrating through the cavity is formed on both sides in the column direction of each of the infrared absorbing sections, Previous Infrared absorption portion and the thermopile on both sides thereof is configured as a single infrared detector, it was that by integrating a plurality of infrared detection elements to a region where the infrared absorbing section occupied the infrared detection region on a single semiconductor substrate.

According to a fifth aspect of the present invention, a delay means for correcting a time lag of output is connected to all the infrared detecting element rows except for a predetermined infrared detecting element row.

According to a sixth aspect of the present invention, a correction infrared detecting element is arranged on the same scanning line as a predetermined infrared detecting element in the predetermined infrared detecting element row, and is arranged on the same scanning line as the correcting infrared detecting element. A time lag calculating means for detecting a time lag is connected to an output of the predetermined infrared detecting element, and the delay means is connected to the connected infrared detecting element row and the predetermined infrared detecting element row in accordance with the detected time lag. The correction time is calculated based on the distance between the correction and the correction.

[0013]

According to the first aspect of the present invention, the infrared detection element array for compensating for the non-detection area is provided so that the detection area of another infrared detection element is located in the non-detection area between the infrared detection elements. Since it is provided, a two-dimensional distribution of infrared rays can be detected without causing a dead area when scanning. Accordingly, this improves the detection sensitivity.

According to the second aspect of the invention, in addition to the effect of the first aspect, the size of the non-detection area between the infrared detection elements and the size of the detection area of the infrared detection elements in the infrared detection element array is increased. Since the number of infrared element rows is set correspondingly and the infrared detection element rows are sequentially shifted, even if the non-detection area is large, the non-detection area can be covered by overlapping the rows.

According to the third aspect of the present invention, the distance between the infrared detecting elements in each infrared detecting element row is set so that the detection areas of the respective infrared detecting element rows do not overlap when viewed from the scanning direction. In order to cover the non-detection area, the number of infrared detection element rows required is the smallest.

According to the fourth aspect of the present invention, since each infrared detecting element is formed on one semiconductor substrate and shares the same cavity, the infrared absorbing sections of each row can be arranged without any gap in the scanning direction. As a result, the time lag of the detection signal of each column is minimized, and the accuracy of correction is improved. In addition, since through holes are formed in both sides of each infrared absorbing portion in the column direction so as to penetrate the hollow portion, heat conduction between the infrared absorbing portions is prevented, and detection accuracy of infrared light is improved.

Further, in the invention according to claim 5, a delay means for performing time correction is connected to all the infrared detecting element rows except for a predetermined infrared detecting element row to correct a time lag. Therefore, it is possible to obtain the same effect as when each infrared detecting element detects infrared rays from the same row. As the correction time, for example, a value calculated based on the distance between the infrared detection element rows and the scanning speed can be used.

According to the sixth aspect of the present invention, there is provided the fifth aspect.
In addition to the effects of the invention described in the above, since the correction infrared detection element is provided on the same scanning line as the predetermined infrared detection element, during scanning, the same output signal as the predetermined infrared detection element is output from the correction infrared detection element. can get. By comparing these two output signals, the time lag of the signals can be detected. Since the time lag of the signal corresponds to the distance between the two elements, using the detected time lag and the distance between the elements, the distance between the infrared detection element row to be corrected and the predetermined infrared detection element row is The time lag can be calculated. The delay means can correct the time lag between the infrared detecting element arrays due to the time lag. This makes it possible to correct the time lag even if the scanning speed is not known in advance.

[0019]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 shows a first embodiment. A plurality of thermal infrared detecting elements having the same configuration as in the related art are arranged in two rows at a predetermined interval, and are formed on the same substrate by a semiconductor process. When this is viewed from the infrared detection surface, as shown in FIG. 1A, the infrared detection element rows 1A and 2A are adjacent to each other without a gap, and are detected between the detection areas 12 of the adjacent infrared detection elements 20 in each row. An interval equal to the length of the area 12 is formed, and the detection area 1 of the adjacent row is formed at the interval.
2 is located. Here, the infrared detecting element has an outer shape having a length L in the column direction, and the length M in the column direction of the detection region 12 is half or more of L. The distance between the centers of the infrared detecting element arrays 1A and 2A is L. As a result, the infrared detection elements are continuous without overlapping the detection areas 12 in the column direction. When the column is scanned in the vertical direction, as shown in FIG. 1B, the scanning regions 20 'of the infrared detecting elements are adjacent to each other without a gap, and form a scanning region having no dead area.

On the other hand, since the infrared detecting element rows 1A and 2A occupy different positions in the scanning direction, there is a time lag in signal output. In order to correct this, a delay circuit 21 as a delay means is connected to the output terminal of each infrared detection element of the infrared detection element array 2A which advances. Infrared detector row 1
Since the distance between A and the center of the column 2A is L, the amount of time shift of the output signal is determined by the distance L and the scanning speed. The calculation method is as follows.
c], assuming that the distance between the infrared absorbing parts is L [μm], the time shift t [sec] is calculated by the following equation. t = L × 10 ⁻⁶ / v If this time lag t is set in the delay circuit 21, the signal output of the infrared detecting element that proceeds forward is corrected so as to be delayed.

The infrared line sensor of this embodiment is configured as described above, and the non-detection area between the infrared detection elements is supplemented by the detection area of another infrared detection element row. Accordingly, when the infrared line sensor scans and detects a two-dimensional distribution of infrared rays, it is possible to perform detection without a dead area. Further, by supplementing the non-detection area, the detection sensitivity is also improved.

In the embodiment, since the length M of the detection area is at least half of the length L of the outer shape, complete interpolation can be achieved by providing one row of infrared detecting elements. If the length is less than half the length, it will not be possible to completely interpolate in one column. In such a case,
As shown in FIG. 2, the number of columns can be increased to, for example, three in accordance with the size of the non-detection region and the detection region, and the non-detection region can be supplemented by being sequentially shifted in the column direction. The distance between the infrared detection elements in each row is adjusted so that the detection areas of the other rows are located within the range of the non-detection area when viewed in the scanning direction as in the embodiment.

Infrared detecting element array 3 in front of the scanning direction
A delay circuit 31 is connected to each infrared detection element also at A.
The delay time of this row is calculated according to the distance from the infrared detection element row 1A, similarly to the infrared detection element row 2A.
Here, since the infrared detecting elements have the same dimensions, the distance from the infrared detecting element row 1A is 2L, so that the correction time may be twice as long as that of the delay circuit 21.

Next, a second embodiment will be described with reference to FIG. In this embodiment, the array of infrared detecting elements of the first embodiment shown in FIG. 1 is used, and the infrared detecting element array 1A is arranged on the same scanning line K as the infrared detecting element 20B outside the infrared detecting element array 2A. The correction infrared detection element 20C is provided on the opposite side with respect to. The correction infrared detection element 20C is in close contact with the infrared detection element row 1A, and the distance between the detection area 12 and each detection area 12 of the infrared detection element row 1A, 2A is L, 2L, respectively.

A time lag calculating device 50 as time lag calculating means is connected to the correction infrared detecting element 20C and the infrared detecting element 20B. A delay circuit 22 with a variable correction time is connected to each infrared detection element of the infrared detection element array 2A.
The delay circuit 22 is connected to the time lag operation device 50. When the infrared detecting element array scans in the scanning direction, the infrared detecting element 20B and the correcting infrared detecting element 20C are on the same scanning line, and therefore, output signals having the same waveform. The time lag calculating device 50 detects the time lag by analyzing the signal. For example, when the signal shown in FIG. 4 is obtained, the time lag t2 can be detected from the peak signal having the same surrounding components and the same intensity E. Delay circuit 22
Performs a correction by setting a correction time according to the detected time lag t2 and the distance between the connected infrared detection row 2A and the infrared detection element 1A. Here, since the distance between the infrared detecting element array 2A and the infrared detecting element 1A is half L of the correcting infrared detecting element 20C, the correction time is set to t.
It may be set to 2/2.

This embodiment is constructed as described above, and a correction infrared detecting element is provided on the same scanning line as one infrared detecting element in the infrared detecting element row, and a time lag calculation is performed based on the detection signals of these two elements. Since the apparatus detects the time lag and the delay circuit sets the correction time according to the detected time lag, correction is possible even if the scanning speed is unknown. In each of the above embodiments, a thermopile thermal infrared detecting element is used. However, the present invention is not limited to this. For example, a porometer type infrared detecting element such as a porometer type infrared detecting element may be applied to any element whose detection area is smaller than the element (outer shape). it can.

Next, a description will be given of a third embodiment in which each infrared detecting element is formed on one semiconductor substrate and the time lag is minimized. FIG. 5 and FIG. 6 are views showing the structure of an infrared line sensor configured by integrating respective infrared detection elements. FIG. 5 is a top view, and FIG. 6 is BB in FIG.
It is sectional drawing. A diaphragm 43 having low thermal conductivity is provided on the surface of the semiconductor substrate 41, a region for forming an infrared detecting element is set on the surface of the diaphragm 43, and the infrared absorbing portions 26 are arranged in two rows as shown in FIG. ing.
An interval of the same size as the infrared absorbing section is formed in the column direction of the infrared absorbing section 26, and another row of infrared absorbing sections is located at the interval when viewed in a scanning direction perpendicular to the row. The right side of each infrared absorption section 26 in the row and the left side of each infrared absorption section 26 in the right row are on a straight line S.

In the formation region of each infrared detecting element, here, four pairs of p-type semiconductors 44 and n-type semiconductors 45 are arranged on both sides in the scanning direction of the two sets of infrared absorbing portions. One end of each of the p-type semiconductor 44 and the n-type semiconductor 45 of each set is connected by the metal electrode 7. The other end of one set is connected to the output terminals 9 and 10, and the other end of the other set of the p-type semiconductor 44 and the n-type semiconductor 45 is connected by the metal electrode 8. The metal electrode 7 serves as a hot junction, and the metal electrode 8 serves as a cold contact. The four sets of p-type semiconductors 44 and n-type semiconductors 45 constitute a thermopile. The difference in heat propagation speed caused by the difference in semiconductor length between the left and right sides can be adjusted by reducing the number of shorter semiconductor groups.

On the diaphragm 43, insulating layers 51, 5
After the formation of 3, the infrared absorbing portion 26 is formed at a predetermined position. Holes 13 and 14 for etching are formed at the four corners of the semiconductor substrate 41, and between the infrared absorbing portions 26 in the column direction and near the straight line S adjacent to the infrared absorbing portion 26. Until the etching hole 15 is formed. From these etching holes, a cavity 42 for thermal separation is formed by micromachining technology so as to cover each infrared absorbing portion 26 except for the peripheral portion where the cold junction is located.

The present embodiment is configured as described above. Since each infrared detecting element is formed on the same semiconductor substrate and has a common cavity, the infrared absorbing elements between the rows of the infrared detecting elements are formed. The distance between them becomes the shortest, the time lag of the output signal at the time of scanning is small, and high correction accuracy can be obtained. Further, since the etching holes are provided on both sides of the infrared absorbing section, heat conduction of the infrared absorbing section is prevented. This prevents heat conduction between the elements from affecting each other.

[Brief description of the drawings]

FIG. 1 is a diagram showing a detection region of an infrared line sensor and a scanning region during scanning in a first embodiment.

FIG. 2 is an explanatory diagram showing a configuration when a detection area of an infrared detection element is small.

FIG. 3 is a diagram showing a second embodiment.

FIG. 4 is a diagram showing detection signals of two infrared detection elements having the same position in the scanning direction.

FIG. 5 is a configuration diagram of an infrared line sensor according to a third embodiment.

FIG. 6 is a sectional view showing a configuration of a third embodiment.

FIG. 7 is a diagram showing a configuration of a thermal infrared detection element.

FIG. 8 is a cross-sectional view illustrating a configuration of a thermal infrared detection element.

FIG. 9 is a diagram showing a detection area of a conventional infrared line sensor and a scanning area during scanning.

[Explanation of symbols]

 1, 41 Semiconductor substrate 2, 42 Cavity 3, 43 Diaphragm 4, 44 P-type semiconductor 5, 45 n-type semiconductor 6, 13, 14, 15 Etching hole 7, 8 Metal electrode 9, 10 Output terminal 11, 17, 51 , 53 Insulating layer 12 Detecting area 20, 20B Infrared detecting element 20 'Scanning area 21, 22, 31, Delay circuit 26 Infrared absorbing section 27 Peripheral area 50 Time shift calculating device 1A, 2A, 3A Infrared detecting element array 20C Infrared detecting for correction Element D Dead area S, K Straight line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Morita F-term (reference) 2G065 AB02 BA14 BA15 BA34 CA30 DA05 2G066 BA04 BA13 BA14 BB20 in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa

Claims (6)

[Claims] A plurality of infrared detecting element rows in which a plurality of infrared detecting elements having a detection area shorter than the element length are arranged are provided in parallel, and when the infrared detecting element rows are viewed from a scanning direction, each infrared detecting element is detected. An infrared line sensor, wherein each of the infrared detection element rows is shifted so that a detection area of another infrared detection element row is located in a non-detection area between the infrared detection elements in the element row. 2. The method according to claim 1, wherein the number of infrared detection element rows is set in accordance with the size of the non-detection area and the detection area of the infrared detection element row, and the infrared detection element rows are sequentially shifted. Item 7. An infrared line sensor according to Item 1. 3. An interval between the infrared detecting elements in each infrared element row is set so that the detection areas of each infrared detecting element row do not overlap when viewed from the scanning direction. Or the infrared line sensor according to 2. 4. A diaphragm having low thermal conductivity is provided on a surface of a semiconductor substrate, and a plurality of rows of infrared absorbing sections are arranged at predetermined intervals on the surface of the diaphragm, and the infrared absorbing sections are arranged perpendicularly to the infrared absorbing sections. When viewed from the scanning direction, in the non-detection region between the infrared absorbing sections in each infrared absorbing section row, the infrared absorbing sections of the other infrared absorbing section rows are located, and opposing sides of the adjacent infrared absorbing sections are located. The semiconductor substrate is set so as to be on the same straight line, and a cavity is formed in the semiconductor substrate under the diaphragm so as to include the infrared absorption unit row. A thermopile in which a cold junction is located on the peripheral side of the infrared absorbing portion is formed in the scanning direction, and a through hole penetrating the hollow portion is formed on both sides in the column direction of each of the infrared absorbing portions. Both The thermopile on the side is constituted as one infrared detecting element, and a plurality of infrared detecting elements having an area occupied by the infrared absorbing portion as an infrared detecting area are integrated on one semiconductor substrate. 3. The infrared line sensor according to 3. 5. An infrared sensor according to claim 1, wherein a delay means for correcting a time lag of an output is connected to all the infrared detecting element rows except for a predetermined infrared detecting element row. Line sensor. 6. A correction infrared detecting element is arranged on the same scanning line as a predetermined infrared detecting element in the predetermined infrared detecting element row, and a predetermined infrared detecting element on the same scanning line as the correction infrared detecting element is provided. The output terminal is connected to a time lag calculating means for detecting a time lag, and the delay means, according to the detected time lag, by a distance between the connected infrared detecting element row and the predetermined infrared detecting element row, 6. The infrared line sensor according to claim 5, wherein the correction is performed by calculating a correction time.