Atomic absorption spectrophotometer

Abstract

An atomic absorption spectrophotometer (1) comprises: a sample collecting part (24) to which a chip (25) for collecting and discharging a sample is attached; a sample heating part (11), wherein an opening (14) into which the sample is injected is provided on the top surface of the sample heating part; a moving mechanism (27) that moves the sample collecting part between a first position at which the sample is collected into the chip and a second position at which the sample is injected from the chip into the opening; a light irradiation part (29) that irradiates the opening with light from a predetermined direction; and an image acquisition part (26) that images the opening from an optical axis direction different from the central axis of light emitted from the light irradiation part.

Description

Technical Field

[0001] The present invention relates to an atomic absorption photometer.

Background Art

[0002] An atomic absorption photometer is used to quantify elements such as metals contained in a liquid sample such as drinking water (for example, Patent Document 1). In an atomic absorption photometer, a liquid sample is thermally decomposed to generate atomic vapor, and the atomic vapor is irradiated with light to measure the absorbance.

[0003] An atomic absorption photometer includes a measurement unit and an autosampler. The measurement unit includes a sample heating unit, a light source that irradiates the atomic vapor generated in the sample heating unit with light, and a detector that detects the light that has passed through the atomic vapor. A sample injection unit for injecting a liquid sample is provided in the sample heating unit. The autosampler includes a sample placement unit on which a plurality of sample containers containing a liquid sample are set, and an 、 tubular no chi tip is attached to the tip of the arm, and a moving mechanism that moves the arm between a sample collection position and a sample injection position. During analysis, a chip attached to the arm of the autosampler is inserted into the inside of the sample container to collect a liquid sample, and the arm is moved to tip inserted into the sample injection unit to inject the liquid sample into the sample heating unit. In many cases, a graphite furnace having an opening that is the sample injection unit provided on the upper surface is used in the sample heating unit.

[0004] In such autosamplers, repeated use can lead to tip deterioration, resulting in errors in sample injection volume, or tip clogging, causing contamination due to previously measured liquid sample remaining inside the tip. To prevent these issues, analysts need to replace the tips at appropriate intervals. Similarly, the sample heating unit also deteriorates with repeated use, requiring analysts to replace it at appropriate intervals. However, because the analyst manually replaces the tips and sample heating unit, mounting errors can occur, such as the tip being attached to the arm at an angle or the sample heating unit being misaligned. In atomic absorption spectrophotometers, for example, the opening size of the sample injection section is 1.8 mm in diameter, and the outer diameter of the tip is 1.5 mm, meaning the allowable error on both sides of the tip's radial direction is very small, less than 0.15 mm. If the mounting error is larger than this, the tip will come into contact with the sample injection section. Therefore, conventionally, after replacing a tip, it was necessary to perform a process called teaching, which involves adjusting the arm's movement control so that the tip of the tip is directly above the sample injection section. Patent documents 2 and 3 describe a method in which images acquired by a camera positioned to simultaneously capture both the tip of the chip and the sample injection section are displayed on a monitor, and the analyst performs teaching while reviewing the images. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Utility Model Registration No. 3127657 [Patent Document 2] International Publication No. 2021 / 124513 [Patent Document 3] Japanese Patent Publication No. 2012-32310 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] During teaching, the sample injection section is photographed with a camera, and the tip is positioned correctly relative to the opening of the sample injection section while checking the image. However, in atomic absorption spectrophotometers, the area around the sample injection section is covered with insulating material to prevent heat from escaping from the sample heating section. In addition, the light source and detector, which are positioned on either side of the sample heating section, are covered with light-shielding material. Furthermore, as mentioned above, the sample heating section is a graphite furnace, and its surface is black. Therefore, even when viewing an image of the graphite furnace surface taken in a dark place covered with insulating and light-shielding material, it is difficult to determine the position of the opening on the surface, and thus it is difficult to align the tip correctly with respect to the opening.

[0007] The problem that this invention aims to solve is to provide a technology that allows the tip to be easily aligned to the correct position relative to the opening of the sample injection section provided in the sample heating section of an atomic absorption spectrophotometer. [Means for solving the problem]

[0008] The atomic absorption spectrophotometer according to the present invention, which was developed to solve the above problems, A sample collection unit to which a tip for collecting and dispensing a sample is attached, The aforementioned sample From the sampling unit, the sample An opening into which the substance is injected is provided on the top surface. , to excite the sample Sample heating section, A moving mechanism moves the sample collection unit between a first position for collecting a sample on the tip and a second position for injecting the sample from the tip into the opening. predetermined illumination A light irradiation unit that irradiates light into the opening from a certain direction, The aforementioned illumination direction An image acquisition unit that captures the aperture from a different optical axis direction. It is equipped with. [Effects of the Invention]

[0009] In the atomic absorption spectrophotometer according to the present invention, the light irradiation unit is predetermined illumination While irradiating light from that direction into the opening provided on the upper surface of the sample heating section, The direction of illuminationThe aperture is photographed by the image acquisition unit from a direction different from the optical axis. In the atomic absorption photometer according to the present invention, the aperture of the sample heating unit is Direction acquired using a light irradiation unit and an image acquisition unit having different The picture optical axes. Therefore, the position of the aperture can be easily confirmed and the chip can be aligned to the correct position.

Brief Description of the Drawings

[0010] [Figure 1] Schematic configuration diagram of an embodiment of the atomic absorption photometer according to the present invention. [Figure 2] Diagram explaining the positional relationship of the aperture, camera, LED, etc. in the atomic absorption photometer of this embodiment [Figure 3] Diagram explaining the relationship between the area irradiated with light from the LED and the field of view of the camera in this embodiment. [Figure 4] Flowchart of the procedure for determining the center position of the aperture and the tip position of the chip in this embodiment. [Figure 5] An example of extracting the area including the tip of the chip in this embodiment. [Figure 6] An example of obtaining the outer contour line of the partial image of the tip of the chip in this embodiment. [Figure 7] An example of obtaining the intersection point of the outer contour line of the chip and the center line of the chip in this embodiment. [Figure 8] An example of the result of determining the tip position of the chip in this embodiment. [Figure 9] An example of extracting an edge from a partial image of the area including the aperture in this embodiment. [Figure 10] Diagram explaining the Hough transform. [Figure 11] An example of extracting the area of the aperture in this embodiment. [Figure 12] An example of the result of determining the center position of the aperture in this embodiment. [Figure 13] A modification for specifying the tip position of the chip.

Mode for Carrying Out the Invention

[0011] An embodiment of the atomic absorption spectrophotometer according to the present invention will be described below with reference to the drawings. In the drawings described below, the main components are shown at a different scale than the actual ones, and some components are omitted from the illustration in order to make the configuration of the main parts easier to understand.

[0012] Figure 1 is a schematic diagram of the atomic absorption spectrophotometer 1 of this embodiment. The atomic absorption spectrophotometer 1 is broadly composed of an analysis unit 3 consisting of a measurement unit 10 and an autosampler 20, and a control / processing unit 4.

[0013] The measuring unit 10 includes a sample heating unit 11, a light source 12 that irradiates the atomic vapor generated in the sample heating unit 11 with light, and a detector 13 that detects the light that has passed through the atomic vapor. The sample heating unit 11 is a cylindrical electric heating furnace with openings on both sides, and an opening 14, which is a sample injection unit, is provided in the center of the top surface. In this embodiment, the size of the sample heating unit 11 is, for example, 5 mm in diameter and 2 cm in length, and the diameter of the opening 14 is, for example, 1.8 mm. Of the optical path from the light source 12 to the detector 13, the portion excluding the vicinity of the opening 14 of the sample heating unit 11 is covered with a light-shielding and heat-insulating member 15 for light shielding and heat insulation.

[0014] The autosampler 20 includes a turntable 21 on which multiple sample containers 22 containing liquid samples are set, an arm 24 with a tip 25 for collecting liquid samples from the sample containers 22 attached to the underside of its tip, and a shaft member 23 to which the base end of the arm 24 is rotatably attached. The autosampler 20 is provided with a moving mechanism 27 for rotating the shaft member 23 and moving it in the horizontal and vertical directions.

[0015] The moving mechanism 27 is configured to allow the arm 24, to which the tip 25 is attached, to move to a first position for collecting a liquid sample (shown by a dashed line in Figure 1), a second position for injecting the liquid sample into the opening 14 of the sample heating unit 11 (shown by a dashed line in Figure 1), and a third position different from the first and second positions (shown by a solid line in Figure 1). For the third position, a location with high contrast with the background when photographing the tip 25 is selected. The arm 24 is moved to the first position and the tip 25 is moved vertically downward to collect the sample from the sample container 22, and the arm 24 is moved to the second position and the tip 25 is moved vertically downward to inject the sample into the opening 14. The outer diameter of the tip 25 used in this embodiment is, for example, 1.5 mm. The tip 25 in this embodiment is tubular (a hollow rod), but it may be of other shapes. Furthermore, for the second position, the arm 24 can also be moved to a position offset by a predetermined length in a predetermined direction from the position when collecting the sample. Hereinafter, the position in which the tip 25 is placed directly above the opening 14 of the sample heating unit 11 when the sample is injected will be referred to as the sample injection position, and the position in which the tip 25 is shifted (offset) by a predetermined distance horizontally and / or vertically from directly above the opening 14 will be referred to as the offset position. The offset position is used when photographing the opening 14 of the sample heating unit 11 with the tip 25 attached to the arm 24. This photography will be described later. Note that moving the arm 24 to the third position is not essential to the present invention, and if the tip position of the tip 25 is determined by photographing the tip 25 at the offset position, it is not necessary to set the third position.

[0016] As shown in Figure 2, a camera 26 is mounted on the underside of the arm 24 closer to the base than the tip 25. An LED 29 (not shown in Figure 1) is mounted on the underside of the arm 24 closer to the tip than the tip 25. The LED 29 is positioned so that its center is off-center from the line connecting the center of the detection surface of the camera 26 and the center of the base of the tip 25. When the arm 24 is in the second position, the LED 29 illuminates the area including the aperture 14 of the sample heating unit 11. The camera 26 is mounted so that, when the arm 24 is in the second position, it captures the area including the aperture 14 of the sample heating unit 11 illuminated by the LED 29 and the tip of the tip 25 in its field of view.

[0017] Figure 3 shows the area illuminated by light from the LED 29 and the field of view of the camera 26 capturing this area when the arm 24 is in the second position. The light emitted from the LED 29 illuminates the area 141 outside the opening 14 on the upper surface of the sample heating unit 11, and also enters through the opening 14 to illuminate a part of the interior area 142 of the sample heating unit 11. The camera 26 captures the illuminated area 141 outside the opening 14 on the upper surface of the sample heating unit 11 and a part of the interior area 143 of the opening 14 in its field of view. The interior area 142 of the sample heating unit 11 illuminated by the LED 29 and the interior area 143 of the sample heating unit 11 captured by the camera 26 are different. Therefore, the image captured by the camera 26 will be bright in the area 141 outside the opening 14 on the upper surface of the sample heating unit 11, and dark in the area 143 inside the opening 14.

[0018] The control and processing unit 4 has a memory unit 41. The memory unit 41 stores various measurement conditions used when measuring with the atomic absorption spectrophotometer 1 (for example, information relating the element to be measured, the type of light source used when measuring that element, and the wavelength of light detected by the detector 13). The memory unit 41 also stores position information for the first position, the second position (including the offset position), and the third position (for example, coordinate information for the second and third positions in a coordinate system with the first position as the origin), and information on the amount of movement of the arm 24 by the movement mechanism 27 when moving the arm 24 between the first position, the second position, and the third position. In addition, the memory unit 41 stores various image processing programs used when determining the center position of the aperture 14 of the sample heating unit 11, filters used for image processing, parameters used for image processing, etc.

[0019] Furthermore, the control and processing unit 4 includes, as functional blocks, an image acquisition unit 42, an image processing unit 43, a position information acquisition unit 44, an analysis control unit 45, and a measurement data processing unit 46. The control and processing unit 4 is essentially a general-purpose personal computer, and the above functional blocks are realized by executing a pre-installed atomic absorption spectrophotometer program on the processor. The control and processing unit 4 is connected to an input unit 51 consisting of a keyboard and mouse, and a display unit 52 consisting of a liquid crystal display.

[0020] The analysis control unit 45 reads the measurement conditions stored in the memory unit 41 in response to input operations by the analyst, and controls the operation of each part constituting the analysis unit 3 to perform the measurement of the sample. The measurement data processing unit 46 analyzes the measurement data of the sample acquired by the analysis control unit 45 by applying appropriate processing to the data. Since the analysis control unit 45 and the measurement data processing unit 46 are the same as those provided in conventional atomic absorption spectrophotometers, a detailed explanation is omitted.

[0021] In the atomic absorption spectrophotometer 1, repeated use can cause the tip 25 to deteriorate, leading to errors in the sample injection volume, or the tip 25 to become clogged, resulting in contamination from previously measured liquid sample remaining inside the tip 25. To prevent these issues, the analyst needs to replace the tip 25 at appropriate intervals. Similarly, the sample heating unit 11 also deteriorates with repeated use, requiring the analyst to replace it at appropriate intervals. Since the analyst manually replaces the tip 25 and the sample heating unit 11, mounting errors can occur, such as the tip 25 being attached to the arm 24 at an angle, or the sample heating unit 11 being misaligned. In the atomic absorption spectrophotometer 1 of this embodiment, the size of the opening 14 of the sample heating unit 11 is 1.8 mm in diameter, and the outer diameter of the tip 25 is 1.5 mm, allowing for a very small radial error of 0.15 mm. If the misalignment between the center position of the tip 25 and the center position of the opening 14 of the sample heating unit 11 is greater than this, the tip 25 will come into contact with the sample injection unit.

[0022] Traditionally, when replacing the tip or sample heating element, both the tip and the opening of the sample heating element were photographed with a camera, and the tip of the tip was aligned with the opening of the sample heating element. However, the sample heating element is located in a recessed position at the bottom of the light-shielding and heat-insulating material, making it difficult to confirm its opening.

[0023] Therefore, in the atomic absorption spectrophotometer 1 of this embodiment, after the analyst replaces the sample heating unit 11 and / or the tip 25, the center position of the opening 14 of the sample heating unit 11 and / or the tip position of the tip 25 are confirmed by the following procedure. Figure 4 is a flowchart of the procedure for confirming the center position of the opening 14 of the sample heating unit 11 and the tip position of the tip 25 in this embodiment.

[0024] When the analyst performs a predetermined input operation to instruct the confirmation of the center of the aperture 14 of the sample heating unit 11 and the position of the tip of the tip 25, the image acquisition unit 42 moves the arm 24 to the third position using the moving mechanism 27 (step 1). The third position is the position shown by the solid line in Figure 1, and when the tip of the tip 25 is photographed at this position, an image can be obtained that shows only the tip of the tip 25 without overlapping with the aperture 14.

[0025] Next, the image acquisition unit 42 lights up the LED 29 to illuminate the area near the tip of the chip 25, and uses the camera 26 to acquire an image of the region including the tip of the chip 25 (step 2), which is then stored in the storage unit 41.

[0026] When the image acquisition unit 42 acquires an image including the tip of the chip 25, the image processing unit 43 first reads the image data from the storage unit 41 and then reads the tip of the chip 25. Department The image (partial image of the chip 25) is extracted (step 3) and displayed on the screen of the display unit 52. The process of extracting a partial image of the chip 25 can be performed, for example, by automatically extracting an image within a predetermined range from the center of the image including the tip of the chip 25. Since the maximum mounting error that may occur when attaching the chip 25 is about a few millimeters, the size of the image to be extracted (the predetermined range mentioned above) can be set in advance so that the tip of the chip 25 is included even if this maximum error occurs. Alternatively, a threshold obtained by statistical processing from the brightness distribution in the image or a predetermined threshold can be used to binarize the brightness value of each pixel constituting the overall image into light / dark, and a partial image including the tip of the chip 25 can be extracted based on attributes corresponding to the shape and area of ​​the tip of the chip 25, such as the area, centroid, outer circumference, and circularity of the clusters of light or dark areas (light areas if the chip 25 is photographed brightly) included in the binarized image.

[0027] Furthermore, as shown in Figure 5, a frame indicating the range of the partial image to be extracted by the above process may be superimposed on the image read from the storage unit 41 and displayed on the screen of the display unit 52, allowing the analyst to change the range of the partial image to be extracted as needed. Note that if the tip of the chip 25 is sufficiently large in the image captured by the camera 26 and there is little extraneous area, or if there are no areas with similar morphological features other than the tip of the chip 25, step 3 may be omitted.

[0028] When a partial image of the chip 25 is extracted, the image processing unit 43 removes noise from that partial image (step 4). For noise removal, for example, noise reduction filters such as median filters and moving average filters, which have been conventionally used in the field of image processing, can be used. If the partial image contains almost no noise, step 4 may be omitted.

[0029] The image processing unit 43 further extracts the largest area cluster from the noise-removed partial image and determines its tip position (step 5). Alternatively, the shape and size of the tip of the chip 25 may be predetermined based on the shape and area of ​​the chip 25 and the magnification during imaging by the camera 26, and clusters that satisfy these shape and size requirements may be extracted.

[0030] When determining the tip position of the chip 25 from a partial image, for example, first, the outline (outline) of the largest area in the partial image is identified (Figure 6). Then, a center line of the chip 25 is drawn midway between the outlines located on both sides of the tip of the chip 25, and the tip position of the chip 25 is determined by finding the intersection point of the center line and the tip of the outline (Figure 7). Figure 8 shows an example of the result of determining the tip position of the chip 25. Once the tip position of the chip 25 is determined by the image processing unit 43, the position information acquisition unit 44 stores the position information in the storage unit 41.

[0031] Once the information of the tip position of the tip 25 is stored in the memory unit 41, the image acquisition unit 42 moves the arm 24 to the second position (offset position) using the movement mechanism 27 (step 6). The second position is originally the position shown by the dashed line in Figure 1, which is the sample injection position where the tip 25 is directly above the opening 14. However, the sample injection When the aperture 14 is photographed at the initial position, the tip 25 overlaps with the aperture 14 in the acquired image. Therefore, the arm 24 is moved to an offset position, which is a predetermined distance and direction from that position. This direction and distance should be determined appropriately, taking into consideration the size and shape of the tip 25, and by taking prior photographs, so that the photographic positions of the tip 25 and the aperture 14 do not overlap.

[0032] Next, the image acquisition unit 42 illuminates the area around the aperture 14 by turning on the LED 29, and acquires an image of the region including the aperture 14 using the camera 26 (step 7), and stores it in the storage unit 41.

[0033] When the image acquisition unit 42 acquires an image including the aperture 14, the image processing unit 43 first reads the image data from the storage unit 41, extracts an image of the area near the aperture 14 (a partial image of the aperture) (step 8), and displays it on the screen of the display unit 52. The process of extracting a partial image of the aperture 14 can be performed, for example, by automatically extracting an image within a predetermined range from the center of the image acquired by the image acquisition unit 42. Since the maximum mounting error of the aperture 14 that may occur when attaching the sample heating unit 11 is only a few millimeters, the size of the image to be extracted (the predetermined range mentioned above) can be set in advance so that the aperture 14 is included even if this maximum error occurs.

[0034] Furthermore, a frame indicating the range of the partial image to be extracted by the above process may be superimposed on the image read from the memory unit 41 and displayed on the screen of the display unit 52, allowing the analyst to change the range of the partial image to be extracted as needed. Note that if the aperture 14 is sufficiently large in the image captured by the camera 26 and there is little extraneous area, or if there are no areas with similar shape features other than the aperture 14, step 8 may be omitted.

[0035] When a partial image of aperture 14 is extracted, the image processing unit 43 removes noise from that partial image (step 9). Noise removal can be performed in the same way as noise removal for the partial image of chip 25. Step 9 may be omitted if the partial image contains almost no noise.

[0036] Next, the image processing unit 43 extracts edges contained in the partial image of the aperture 14 from which noise has been removed (step 10). Edge extraction can also be performed using edge processing filters such as the Sobel filter, Laplacian filter, or Canny filter, which have been conventionally used in the field of image processing. Figure 9 shows an example of a partial image from which edges have been extracted. In this example, edges contained in the partial image from which noise has been removed are extracted, but instead of the edge extraction process, the brightness value of each pixel may be binarized into light / dark using a predetermined brightness threshold or a threshold obtained from the brightness distribution in the image.

[0037] Next, the image processing unit 43 extracts a circular region corresponding to the aperture 14 from the partial image after edge extraction and determines its center position (step 11). The circular region can be extracted, for example, by the Hough transform. Specifically, as shown in Figure 10, in the partial image after edge extraction, circles with radius r are drawn centered on the position of each pixel (edge ​​point) that constitutes the edge, and the intersection point where the most circles overlap is determined as the center position of the aperture 14. Figure 11 shows an example of an image in which the circular region corresponding to the aperture 14 has been extracted. The size of the radius r can be predetermined from the actual radius of the aperture 14 and the magnification factor when the image is acquired by the camera 26. With this method, the center position of the aperture 14 can be determined with pixel-level spatial resolution.

[0038] The above process using the Hough transform in this embodiment is a method for determining the center position of the aperture 14 by so-called majority vote. Therefore, even if a part of the edge of the aperture 14 is missing in the partial image of the aperture 14 after edge extraction, the circle corresponding to the aperture 14 can be detected. In the atomic absorption spectrophotometer 1, the heating furnace constituting the sample heating section 11 deteriorates with repeated use. As a result, the contrast between the inside and periphery of the aperture 14 decreases in the partial image of the aperture 14, and a part of the edge corresponding to the aperture 14 may not be extracted. By using the Hough transform as in this embodiment, the center position of the aperture 14 can be determined even if a part of the edge corresponding to the aperture 14 is not extracted.

[0039] To determine the center position of the aperture 14 with higher resolution, the Hough transform is used to find the intersection point where the most circles overlap, similar to step 11 above. Then, the circle that encloses the edge points (pixels) that draw circles passing through that intersection point (in other words, the circumscribed circle of all edge points that draw circles passing through that intersection point) is determined, and the center of that circumscribed circle is determined as the center position of the aperture 14. This method allows the center position of the aperture 14 to be determined with spatial resolution at or above the pixel level. Once the center position of the aperture 14 is determined by the image processing unit 43, the position information acquisition unit 44 stores the position information in the storage unit 41.

[0040] If, in step 8, only the portion corresponding to aperture 14 has been extracted, the circumscribed circle of each pixel (edge ​​point) constituting the edge may be directly determined from the extracted partial image without performing a Hough transform, and the center of that circumscribed circle may be determined as the center position of aperture 14. Figure 12 shows an example of the result of determining the center position 144 of aperture 14.

[0041] Once the tip position of the tip 25 and the center position 144 of the opening 14 are determined, the position information acquisition unit 44 calculates the distance between them based on the position information stored in the storage unit 41 (step 12) and stores it in the storage unit 41. Then, when measuring the sample thereafter, the moving mechanism 27 moves the arm 24 between the first position, second position, and third position based on the distance information calculated by the position information acquisition unit 44. This eliminates mounting errors that may have occurred when the analyst replaced the sample heating unit 11 or the tip 25.

[0042] The above embodiments are merely examples and can be modified as appropriate in accordance with the spirit of the present invention.

[0043] In the above embodiment, the camera 26 and LED 29 are attached to the arm 24, and the camera 26 and LED 29 move together with the arm 24. However, one or both of the camera 26 and LED 29 may be fixed to the arm 24 without being attached. In that case, the camera 26 and LED 29 may be positioned at the third position and the offset position, respectively.

[0044] In the above embodiment, the tip of the chip 25 was photographed at the third position, but the area including the aperture 14 and the tip of the chip 25 may also be photographed at the same position (an offset position from the second position). However, by photographing at the third position as in the above embodiment, the inclusion of objects other than the chip 25 can be eliminated, and an improvement in the detection accuracy of the tip position of the chip 25 can be expected. In many cases, the chip 25 is made of resin, and when light is shone from the LED 29, the position of the chip 25 becomes bright. Therefore, it is preferable to select a location for the third position where the background is dark and the contrast with the chip 25 is high. Alternatively, a light source that emits light of a wavelength that does not pass through the material (resin, etc.) that makes up the chip 25 may be used, and a position with a bright background may be set as the third position, and the chip 25 may be photographed at that third position to obtain an image in which the chip 25 is dark and the background is bright.

[0045] In the above embodiment, the center position of the aperture 14 and the tip position of the chip 25 were identified by image processing, but image processing is not essential to the present invention, and the image of the tip of the aperture 14 and / or chip 25 is displayed on the screen of the display unit 52. To represent The image may be shown, and the analyst may examine it to determine the center position of the aperture 14 and the tip position of the tip 25.

[0046] Furthermore, if the image obtained after binarizing the luminance values ​​of a partial image of the aperture 14 contains numerous clusters of bright (or dark) areas smaller than the aperture 14, noise can be removed by combining morphological processing or other methods to remove the clusters smaller than the aperture 14 from the image, thereby obtaining a partial image that emphasizes the aperture 14. Moreover, an image pattern corresponding to the shape of the aperture 14 can be stored in the memory unit 41 in advance, and the position of the aperture 14 can be identified by pattern matching to extract a partial image.

[0047] A method different from the above embodiment can be used to determine the center position of the aperture 14. For example, after obtaining the outline (outline) of the aperture 14 by the Hough transform, similar to the above embodiment, the centroid of the multiple pixels on which the outline is located may be determined as the center position of the aperture 14. Alternatively, the equation of the circle that best approximates the outline can be obtained by the least squares method, and the center position of the aperture 14 can be determined from that equation.

[0048] Furthermore, when photographing the chip 25 at the third position, a reference image of only the background at the third position can be stored in the storage unit 41, and a partial image of the chip 25 can be extracted by taking the difference between the reference image and the image obtained by photographing the tip of the chip 25 with the camera 26.

[0049] Furthermore, if, similar to the above embodiment, the chip 25 is photographed at the third position and an image is obtained in which the boundary between the chip 25 and its background is clearly visible, the tip position of the chip 25 may be determined simply by extracting the pixel located at the very tip (or the midpoint of the pixels if there are multiple pixels lined up at the tip), without performing any processing such as extracting the outline. Alternatively, the minimum bounding rectangle of the block constituting the chip 25 may be determined in the partial image, and the midpoint of the short side located on the tip side may be determined as the tip position of the chip 25. Or, as shown in Figure 13, the two minimum bounding rectangles Long side The tip position of the tip of the tip 25 may be identified by the intersection of the line located in the middle (the center line crossing the minor axis of the rectangle) and the boundary portion on the tip side. Furthermore, when photographing the tip 25 at the third position, another camera can be placed directly below the tip 25 to photograph the tip 25, and a shape corresponding to the cross-section of the tip 25 (circular, rectangular, etc.) can be extracted from the image, and its center can be identified as the tip position of the tip 25. When extracting circular or other shapes from the image, various methods that can be used when identifying the aperture 14 can be used.

[0050] In the above embodiment, when the arm 24 is in the second position, the components are arranged so that in a plan view, the LED 29 is located on the opposite side of the opening 14 from the camera 26. However, the components may also be arranged so that the LED 29 and the camera 26 are located on the same side of the opening 14. In that case as well, the optical axes of the LED 29 and the camera 26 are arranged to be different from each other.

[0051] [Aspect] Those skilled in the art will understand that the above-described exemplary embodiments are specific examples of the following embodiments.

[0052] (Section 1) An atomic absorption spectrophotometer according to one aspect of the present invention is A sample collection unit to which a tip for collecting and dispensing a sample is attached, The aforementioned sample From the sampling unit, the sample An opening into which the substance is injected is provided on the top surface. , to excite the sample Sample heating section, A moving mechanism moves the sample collection unit between a first position for collecting a sample on the tip and a second position for injecting the sample from the tip into the opening. predetermined illumination A light irradiation unit that irradiates light into the opening from a certain direction, The aforementioned illumination direction An image acquisition unit that captures the aperture from a different optical axis direction. It is equipped with.

[0053] In the atomic absorption spectrophotometer described in paragraph 1, the light irradiation unit is predetermined illumination While irradiating light from that direction into the opening provided on the upper surface of the sample heating section, The direction of illumination The aperture is photographed by the image acquisition unit from a different optical axis. In the atomic absorption spectrophotometer of paragraph 1, the aperture of the sample heating section is photographed using the light irradiation unit and the image acquisition unit which have different optical axes. of, contrast between light and dark there The position of the aperture can be easily confirmed in order to acquire an image.

[0054] (Section 2) In the atomic absorption spectrophotometer described in paragraph 1, The image acquisition unit is positioned to capture within the aperture a region that is not illuminated by light from the light irradiation unit.

[0055] (Section 3) In the atomic absorption spectrophotometer described in paragraph 1 or 2, In a plan view, the light irradiation unit, the image acquisition unit, and the sample heating unit are arranged such that the light irradiation unit is located on the opposite side of the opening from the image acquisition unit.

[0056] (Section 4) In the atomic absorption spectrophotometer described in paragraph 1 or 2, In a plan view, the light irradiation unit, the image acquisition unit, and the sample heating unit are arranged such that the light irradiation unit and the image acquisition unit are located on the same side with respect to the aperture.

[0057] In the atomic absorption spectrophotometers described in paragraphs 2 to 4, the position of the aperture can be more accurately confirmed by capturing an image with high contrast, where the top surface of the sample heating section is bright and the aperture is dark. In the atomic absorption spectrophotometers described in paragraphs 2 to 4, even when photographing the aperture with a tip attached to the sample collection section, the inside of the aperture can be photographed in darkness while the tip is photographed in brightness, making it easy to distinguish between the two.

[0058] (Section 5) In an atomic absorption spectrophotometer described in any of paragraphs 1 to 4, The moving mechanism further moves the sample collection unit to a third position different from the first and second positions. The image acquisition unit photographs the tip of the chip when the sample collection unit is in the third position.

[0059] In atomic absorption spectrophotometers, resin tips are often used. When a resin tip is photographed, the tip's position becomes brighter. In the atomic absorption spectrophotometer described in Section 5, the tip can be photographed independently of the sample container at the first position and the sample heating unit at the second position. Furthermore, it is preferable to select a location for the third position that has a background with high contrast to the tip. For example, by setting a third position with a dark background and brightly photographing the tip of the tip at this third position, an image with high contrast between the tip and the background can be obtained. If the tip is to be photographed in darkness by irradiating it with light of a wavelength that does not pass through the tip, a third position with a bright background may be set. In addition, the silhouette of the tip may be photographed (transmitted illumination) by irradiating light from the back of the tip.

[0060] (Section 6) In an atomic absorption spectrophotometer described in any of paragraphs 1 to 5, The light irradiation unit and the image acquisition unit are attached to the sample collection unit.

[0061] In the atomic absorption spectrophotometer described in Section 6, the relative positions of the light irradiation unit and the image acquisition unit are fixed, so the aperture can always be photographed under the same conditions.

[0062] (Section 7) In the atomic absorption spectrophotometer described in paragraph 6, The moving mechanism further moves the sample collection unit to an offset position that is offset horizontally and / or vertically from the second position. The aforementioned image acquisition unit, The sample collection unit The aperture is photographed when it is in the offset position.

[0063] In the atomic absorption spectrophotometer described in Section 7, by appropriately determining the offset amount, it is possible to acquire images in which the position of the aperture of the sample heating section and the tip of the chip are shifted.

[0064] (Section 8) In the atomic absorption spectrophotometer described in any of paragraphs 1 to 7, further, Image processing unit determines the center position of the aperture by performing image processing on the image of the aperture captured by the image acquisition unit. It is equipped with.

[0065] (Section 9) In the atomic absorption spectrophotometer described in paragraph 8, The aforementioned opening is circular, The image processing unit extracts the outline of the aperture by performing a process to extract edges included in the image of the aperture or a process to binarize the brightness value of each pixel in the image of the aperture, determines the region corresponding to the aperture by performing a Hough transform based on the position of the pixel corresponding to the outline and the radius value of a predetermined range, and determines the center position of the aperture by identifying the center of the region.

[0066] (Section 10) In the atomic absorption spectrophotometer described in paragraph 8 or 9, The image processing unit extracts the region of the aperture by performing a process to extract edges included in the image of the aperture or a process to binarize the brightness value of each pixel in the image of the aperture, determines the circumscribed circle that encloses the pixels corresponding to the region, and determines the center of the circumscribed circle as the center position of the aperture.

[0067] In the atomic absorption spectrophotometers described in paragraphs 8 to 10, the central position of the aperture is determined by the image processing unit, allowing the analyst to easily determine the central position of the aperture without having to examine the image themselves. Furthermore, as an image processing method for determining the central position of the aperture, for example, as in the atomic absorption spectrophotometer described in paragraph 9, the contour line of the aperture is extracted, and the region of the aperture is extracted by a Hough transform based on the position of the pixel corresponding to the contour line and the radius value of a predetermined range. Alternatively, as in the atomic absorption spectrophotometer described in paragraph 10, the region of the aperture is extracted, and the central position of the aperture is determined by finding the circumscribed circle that encloses the pixels corresponding to that region. Moreover, the methods of the atomic absorption spectrophotometers described in paragraphs 9 and 10 can be combined to extract the region of the aperture by a Hough transform, find its circumscribed circle, and identify the center of the circumscribed circle to determine the central position of the aperture. In the atomic absorption spectrophotometer described in paragraph 9, the central position of the aperture can be determined with pixel-level resolution, while in the atomic absorption spectrophotometer described in paragraph 10, the central position of the aperture can be determined with resolution greater than pixel-level.

[0068] (Section 11) In an atomic absorption spectrophotometer described in any of paragraphs 8 to 10, The image processing unit further determines the tip position of the chip by extracting the outline of the chip and identifying its tip by performing processes such as extracting edges included in the image of the chip captured by the image acquisition unit, binarizing the brightness value of each pixel in the image of the chip, or calculating the difference between a pre-prepared background image that does not include the chip and the image of the chip.

[0069] (Section 12) In the atomic absorption spectrophotometer described in paragraph 11, The image processing unit determines the tip position of the chip by defining the center line of the chip midway between the outline lines of the chip located on both sides of the tip of the contour line and finding the intersection point of the center line and the tip, or by finding a rectangle circumscribing the contour line and identifying the intersection point of the short side of the rectangle located on the tip side of the chip and the center lines of the two long sides of the rectangle.

[0070] In the atomic absorption spectrophotometers described in paragraphs 11 and 12, the tip position of the tip can be determined in addition to the center position of the aperture.

[0071] (Section 13) In an atomic absorption spectrophotometer described in any of paragraphs 8 to 12, further, A position information acquisition unit calculates the distance between the tip of the chip and the center of the opening based on the processing results by the image processing unit. It is equipped with.

[0072] In the atomic absorption spectrophotometer described in paragraph 13, the position information acquisition unit can calculate the distance between the tip of the tip and the center of the aperture after correcting any positional shifts that may have occurred during sample heating or tip replacement, based on the processing results from the image processing unit. [Explanation of Symbols]

[0073] 1...Atomic absorption photometer 10…Measuring part 11…Sample heating section 12...Light source 13… Detector 14...Aperture 15…Light-blocking and heat-insulating materials 20... Autosampler 21... Turntable 22… Sample container 23...Shaft member 24... Arm 25... Tips 26... Camera 27...Movement mechanism 29…LED 3…Analysis Department 4…Control and Processing Unit 41...Storage section 42…Image acquisition unit 43…Image Processing Unit 44...Position information acquisition unit 45…Analysis and Control Section 46...Measurement data processing unit 51...Input section 52…Display section

Claims

1. A sample collection unit to which a vertically extending tip is attached for collecting and dispensing samples, A cylindrical body arranged so as to have holes extending horizontally, a sample heating section having an opening on its upper surface into which the sample is injected from the tip, A moving mechanism moves the sample collection unit between a first position for collecting a sample on the tip and a second position for injecting the sample from the tip into the opening. A light irradiation unit that irradiates light into the aperture from a predetermined illumination direction, An image acquisition unit that captures the aperture from an optical axis direction different from the illumination direction. Equipped with, The region inside the sample heating section illuminated by the light irradiation unit through the aperture is different from the region inside the sample heating section included in the field of view of the image acquisition unit. The image acquisition unit is positioned to capture in its field of view an area inside the aperture that is not illuminated by light from the light irradiation unit, and the chip is positioned above the aperture, with the optical axis tilted from the vertical when photographing the aperture, in this atomic absorption spectrophotometer.

2. The atomic absorption spectrophotometer according to claim 1, wherein, in a plan view, the light irradiation unit, the image acquisition unit, and the sample heating unit are arranged such that the light irradiation unit is located on the opposite side of the aperture from the image acquisition unit.

3. The atomic absorption spectrophotometer according to claim 1, wherein, in a plan view, the light irradiation unit, the image acquisition unit, and the sample heating unit are arranged such that the light irradiation unit and the image acquisition unit are located on the same side with respect to the aperture.

4. The moving mechanism further moves the sample collection unit to a third position different from the first and second positions. The atomic absorption spectrophotometer according to claim 1, wherein the image acquisition unit photographs the tip of the chip when the sample collection unit is in the third position.

5. The atomic absorption spectrophotometer according to claim 1, wherein the light irradiation unit and the image acquisition unit are attached to the sample collection unit.

6. The moving mechanism further moves the sample collection unit to an offset position that is offset horizontally and / or vertically from the second position. The atomic absorption spectrophotometer according to claim 5, wherein the image acquisition unit photographs the aperture when the sample collection unit is in the offset position.

7. moreover, Image processing unit determines the center position of the aperture by performing image processing on the image of the aperture captured by the image acquisition unit. The atomic absorption spectrophotometer according to claim 1, comprising:

8. The aforementioned opening is circular, The atomic absorption spectrophotometer according to claim 7, wherein the image processing unit extracts the contour line of the aperture by performing a process to extract edges included in the image of the aperture or a process to binarize the brightness value of each pixel in the image of the aperture, determines the region corresponding to the aperture by performing a Hough transform based on the position of the pixel corresponding to the contour line and the radius value of a predetermined range, and determines the central position of the aperture by identifying the center of the region.

9. The atomic absorption spectrophotometer according to claim 7, wherein the image processing unit extracts a region of the aperture by performing a process to extract edges included in the image of the aperture or a process to binarize the brightness value of each pixel in the image of the aperture, determines a circumscribed circle that encloses the pixels corresponding to the region, and determines the center of the circumscribed circle as the center position of the aperture.

10. The atomic absorption spectrophotometer according to claim 7, wherein the image processing unit further determines the tip position of the chip by extracting the outline of the chip and identifying its tip by performing a process to extract edges included in the image of the chip captured by the image acquisition unit, a process to binarize the brightness value of each pixel in the image of the chip, or a process to calculate the difference between a pre-prepared background image that does not include the chip and the image of the chip.

11. The atomic absorption spectrophotometer according to claim 10, wherein the image processing unit determines the tip position of the chip by performing a process of defining the center line of the chip in the middle of the outline lines of the chip that are located on both sides of the tip of the contour line and finding the intersection point of the center line and the tip, or by performing a process of finding a rectangle that is circumscribing the contour line and identifying the intersection point of the short side of the rectangle located on the tip side of the chip and the center lines of the two long sides of the rectangle.

12. moreover, A position information acquisition unit calculates the distance between the tip of the chip and the center of the opening based on the processing results from the image processing unit. The atomic absorption spectrophotometer according to claim 7, comprising:

Images