Liquid collection and injection device

Abstract

This liquid collection and injection device for collecting a liquid and injecting the liquid into a predetermined place includes: a tubular tip (153) for suctioning and discharging the liquid in a state in which the leading end of the tip is directed downward; movement mechanisms (160, 181, 182) for moving the tip in a three-dimensional space; an imaging unit (155) for imaging the leading end of the tip; a photoelectric sensor (170) having a light projection unit (171) and a light reception unit (172); and a position specifying unit (123) for specifying a position in the three-dimensional space of the leading end of the tip on the basis of an image of the leading end of the tip imaged by the imaging unit and detection information obtained by detecting the leading end of the tip by means of the photoelectric sensor.

Description

liquid collection injection device

[0001] The present invention relates to a liquid collection and injection device.

[0002] Atomic absorption spectrophotometers are used to quantify elements such as metals in liquids such as drinking water. In an atomic absorption spectrophotometer, a liquid sample is thermally decomposed to generate atomic vapor, which is then irradiated with light to obtain an absorption spectrum, thereby performing qualitative and quantitative analysis of the sample.

[0003] An atomic absorption spectrophotometer includes a measurement unit and an autosampler. The measurement unit includes a sample heating unit consisting of a graphite furnace, a light source that irradiates light onto atomic vapor generated in the sample heating unit, and a detector that detects the light that has passed through the atomic vapor. The sample heating unit is provided with a sample injection port for injecting liquid samples. The autosampler includes a sample mounting unit on which multiple sample containers containing liquid samples are set, a capillary tip for aspirating and dispensing the liquid sample, an arm to which the tip is attached, and a movement mechanism for moving the arm vertically and horizontally. During analysis, the tip attached to the arm of the autosampler is inserted into the sample container to collect the liquid sample. The arm is then moved to insert the tip of the tip into the sample injection port, and the liquid sample is injected into the sample heating unit.

[0004] With such autosamplers, repeated use can cause tip degradation, resulting in errors in sample injection volume, or clogged tips, resulting in previously measured liquid samples remaining in the tip, leading to contamination. To prevent these issues, analysts must replace tips at appropriate times. Furthermore, the sample heating unit also deteriorates with repeated use, requiring analysts to replace the unit at appropriate times. When replacing the tip or sample heating unit, analysts must manually install the unit, potentially resulting in installation errors 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 sample injection port has a diameter of approximately 1.5 mm to 2.0 mm, and the outer diameter of the tip is approximately 0.8 mm to 1.5 mm. Therefore, the allowable radial error (tolerance) of the tip is very small. If the installation error exceeds this tolerance, the tip will come into contact with the periphery of the sample injection port. Therefore, after replacing a tip, a procedure called teaching was previously required, in which the arm movement control was adjusted so that the tip's tip was positioned directly above the center of the sample injection port. Patent Document 1 describes a method in which an image acquired by a camera positioned to simultaneously capture both the tip of the chip and the sample injection port is displayed on a monitor, and an analyst performs teaching while checking the image. Patent Document 2 describes a method in which, during teaching, the position of the tip of the chip and the center position of the sample injection port are identified by analyzing an image acquired by a camera positioned to simultaneously capture both the tip of the chip and the sample injection port.

[0005] International Publication No. 2021 / 124513 International Publication No. 2023 / 188553

[0006] However, there are cases where the position of the tip of the chip in the depth direction of the field of view of the camera cannot be accurately identified from an image captured by a single camera. If multiple cameras are used to capture images of the tip of the chip and the tip position is identified from the multiple images obtained, it would be possible to identify the position with high accuracy, but this would result in a problem of increased manufacturing costs.

[0007] This problem is not limited to the autosampler of the atomic absorption spectrophotometer, but is common to any liquid collection and injection device that collects liquid using a tubular tip and injects it into a predetermined location.

[0008] The problem to be solved by the present invention is to realize, at low cost, accurate identification of the tip end position in a liquid collection and injection device that collects liquid using a thin tubular tip and injects it into a predetermined location.

[0009] The liquid collection and injection device of the present invention, which has been made to solve the above-mentioned problems, is a liquid collection and injection device that collects liquid and injects it into a predetermined location, and has: a tubular tip that aspirates and dispenses liquid with the tip facing downwards; a movement mechanism that moves the tip within three-dimensional space; an imaging unit that photographs the tip of the tip; a photoelectric sensor having a light-emitting unit and a light-receiving unit; and a position identification unit that identifies the position of the tip of the tip in three-dimensional space based on the image of the tip of the tip photographed by the imaging unit and detection information obtained by detecting the tip of the tip with the photoelectric sensor.

[0010] According to the liquid collection and injection device of the present invention having the above-mentioned configuration, it is possible to accurately identify the tip end position at low cost.

[0011] FIG. 1 is a schematic configuration diagram of an atomic absorption spectrophotometer according to a first embodiment of the present invention. FIG. 2 is a side view of a tip movement mechanism in the same embodiment. FIG. 3 is a perspective view showing the tip of an arm and a photoelectric sensor in the same embodiment. FIG. 4 is a schematic view showing a light receiving unit of a photoelectric sensor in the same embodiment. FIG. 5 is a flowchart showing the procedure for determining the center position of a sample injection port and the tip position of a tip in the same embodiment. FIG. 6 is a schematic configuration diagram showing another example of the configuration of an analytical unit in the same embodiment. FIG. 7 is a schematic configuration diagram of an atomic absorption spectrophotometer according to a second embodiment of the present invention. FIG. 8 is a side view of a tip movement mechanism in the same embodiment. FIG. 9 is a flowchart showing the procedure for determining the center position of a sample injection port and the tip position of a tip in the same embodiment. FIG. 10 is a side view of another example of a tip movement mechanism in the same embodiment. FIG. 11 is a graph showing the relationship between working distance and arm height during detection. FIG. 12 is an image showing the result of aligning the tip tip and the sample injection port using only an image captured by a camera. FIG. 13 is an image showing the result of aligning the tip tip and the sample injection port based on an image captured by a camera and the detection results of a photoelectric sensor.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the drawings are drawn at a scale different from the actual scale and some components are omitted in order to clearly show the configuration of the main parts.

[0013] [First Embodiment] Figure 1 is a schematic diagram of an atomic absorption spectrophotometer according to a first embodiment of the present invention. This atomic absorption spectrophotometer is a frameless (electrically heated) atomic absorption spectrophotometer that atomizes a sample without using a flame, and is equipped with an analysis unit 110 having a measurement unit 140 and an autosampler 150, and a control / processing unit 120 that controls the operation of the analysis unit 110 and processes data acquired by the analysis unit 110. Note that in Figure 1, the analysis unit 110 is shown as viewed from above.

[0014] The measurement unit 140 includes a sample heating unit 141 (corresponding to the heating furnace in the present invention), a light source 142 that irradiates light onto the atomic vapor generated in the sample heating unit 141, and a detection unit 143 that detects the light that has passed through the atomic vapor by dispersing it. The sample heating unit 141 is an electrically heated cylindrical furnace with both ends open, and a sample injection port 144, which is a circular hole for injecting a sample, is formed on the circumferential surface near the center of its length. The sample heating unit 141 is attached to the measurement unit 140 with its axis aligned substantially horizontally, one end facing the light source 142, the other end facing the detection unit 143, and the sample injection port 144 facing upward. In this embodiment, the size of the sample heating unit 141 is, for example, 3 to 7 mm in diameter and 1.5 to 3 cm in length, but is not limited thereto. The dimensions of the sample injection port 144 are small so as not to diffuse the atomic vapor generated in the sample heating unit 141, and its diameter is, for example, 1.5 mm to 2.0 mm. The optical path from the light source 142 to the detection unit 143, except for the vicinity of the sample injection port 144, is covered with a light-shielding and heat-insulating member 145 for light-shielding and heat-insulating purposes.

[0015] The autosampler 150 includes a turntable 152 on which a plurality of sample containers 151 containing liquid samples are set, a tip moving mechanism 160 for moving a tip 153 for aspirating and dispensing the liquid sample along a predetermined rotational orbit and up and down (the Z-axis direction in FIG. 1 ), a photoelectric sensor 170, a stage 181 on which the turntable 152 and tip moving mechanism 160 are mounted, and a stage drive unit 182 for moving the stage 181 in two mutually perpendicular axial directions (the X-axis direction and the Y-axis direction in FIG. 1 ) within a horizontal plane. The tip moving mechanism 160, the stage 181, and the stage drive unit 182 correspond to the moving mechanism in the present invention.

[0016] As shown in Figure 2, the chip moving mechanism 160 includes an arm 161 extending horizontally, an axial member 162 extending downward from one end (base end) of the arm 161, and an arm drive unit 163 that rotates the axial member 162 to pivot the arm 161 and moves the axial member 162 up and down to move the arm 161 up and down.

[0017] A tip mounting portion 154 is provided on the underside near the tip of the arm 161, and a thin tubular tip 153 is attached to the tip mounting portion 154 with its tip facing downward. One end of a liquid delivery tube (not shown) is connected to the base end of the tip 153, and the other end of the liquid delivery tube is connected to a suction / discharge mechanism (not shown), such as a syringe. The outer diameter of the tip portion of the tip 153 is smaller than the diameter of the sample injection port 144, and is, for example, approximately 0.8 mm to 1.5 mm. Note that, while FIG. 2 shows the tip 153 having a constant outer diameter along its entire length, this is not limiting, and the tip 153 may have a tapered shape in which the outer diameter gradually decreases toward the tip.

[0018] As shown in FIG. 2 , a camera 155 (corresponding to the imaging unit in the present invention) is attached to the underside of the arm 161, closer to the base end than the tip mounting portion 154. The camera 155 is attached so that the tip of the tip 153 is included in its field of view. It may be attached facing directly downward as shown in FIG. 2 , or it may be attached in an inclined position so that the tip of the tip 153 is located near the center of the field of view. Furthermore, a light 156 is attached to the underside of the arm 161, closer to the tip end than the tip mounting portion 154. The light 156 is attached so that it can illuminate the tip of the tip 153. It may be attached facing directly downward as shown in FIG. 2 , or it may be attached in an inclined position so that the tip of the tip 153 is located near the center of the area illuminated by the light 156. The light 156 may be, for example, an LED, but is not limited to this.

[0019] The arm 161 can be moved by the tip moving mechanism 160 to an initial position shown by a solid line in Fig. 1 , a sample collection position shown by a dashed line, and an imaging position shown by a dashed line. Furthermore, the arm 161 can be moved by the tip moving mechanism 160 and the stage driving unit 182 to a detection position shown by a two-dot chain line in Fig. 1 and a sample injection position shown by a three-dot chain line. When the arm 161 is in the sample collection position, the tip of the tip 153 is inserted into the sample container 151 located at a predetermined position on the turntable 152, and when the arm 161 is in the detection position, the tip of the tip 153 is inserted between the light projecting unit 171 and the light receiving unit 172 of the photoelectric sensor 170. Furthermore, when the arm 161 is in the sample injection position, the tip of the tip 153 is inserted into the sample injection port 144. When collecting a sample from the sample container 151, the tip moving mechanism 160 moves the arm 161 to the sample collection position, and then the above-mentioned suction and discharge mechanism aspirates the sample into the tip 153. When injecting the aspirated sample into the sample injection port 144, the tip moving mechanism 160 and the stage driving unit 182 move the arm 161 to the sample injection position, and then the above-mentioned suction and discharge mechanism discharges the sample into the sample heating unit 141. The above-mentioned photographing position is a position where the camera 155 can capture an image that includes the tip of the tip 153 but does not include the sample injection port 144.

[0020] Furthermore, the arm 161 can be moved to an offset position (not shown), which is a position offset by a predetermined distance in a predetermined direction from the sample injection position, by the action of the tip moving mechanism 160 and the stage driving unit 182. The offset position is a position where the camera 155 can photograph the sample injection port 144 without overlapping with the tip 153, and may be a position where the arm 161 is moved upward by a predetermined distance from the sample injection position, or may be a position where the arm 161 is rotated by a predetermined angle from the sample injection position. Hereinafter, the above-mentioned sample collection position, photographing position, detection position, sample injection position, and offset position may be collectively referred to as target positions.

[0021] As shown in FIG. 1 , the photoelectric sensor 170 is a so-called transmission-type (groove-shaped) photoelectric sensor having a light-emitting unit 171 and a light-receiving unit 172, which are arranged facing each other at a distance from each other. As shown in FIG. 3 , the light-emitting unit 171 and the light-receiving unit 172 are housed in a U-shaped housing 173 (however, the light-receiving unit 172 is not shown in the figure), and are configured so that light emitted from the light-emitting unit 171 strikes the light-receiving unit 172. The photoelectric sensor 170 is fixed at a predetermined height within the autosampler 150 by a support member 174. Note that, although the photoelectric sensor 170 is disposed at a position away from the stage 181 in FIG. 1 , the photoelectric sensor 170 may also be disposed on the stage 181. The light-emitting unit 171 may be, for example, an LED element, and the light-receiving unit 172 may be, for example, a photodiode, but this is not a limitation. As shown in Fig. 4, the light receiving surface of the light receiving unit 172 of the photoelectric sensor 170 is divided into two regions. Hereinafter, one region of the divided light receiving surface will be referred to as a first region 175, and the other region will be referred to as a second region 176. As shown in Figs. 1 and 4, the photoelectric sensor 170 is arranged so that the light projecting unit 171 and the light receiving unit 172 are located in substantially the same horizontal plane, and the first region 175 and second region 176 of the light receiving unit 172 are aligned in the lateral direction (horizontal direction).

[0022] The control / processing unit 120 includes functional blocks, such as a position information acquisition control unit 121, an image analysis unit 122, a position identification unit 123, a teaching information generation unit 124, an analysis control unit 125, and a measurement data processing unit 126. The control / processing unit 120 also includes a storage unit 127. The functions of the control / processing unit 120 are realized by a computer including a CPU, memory, a large-capacity storage medium (e.g., a hard disk), and the like. While the computer may be a dedicated computer for the atomic absorption spectrophotometer, a general-purpose computer such as a personal computer is typically used. A predetermined program is pre-installed on the computer, and the functions of the above functional blocks are realized in software by the CPU executing the program. The function of the storage unit 127 is also realized by the large-capacity storage medium. The computer is connected to an input unit 128 through which a user (analyst) inputs various instructions and a display unit 129 for displaying various information. The display unit 129 is configured, for example, by a liquid crystal display, and the input unit 128 is configured, for example, by a keyboard, a pointing device such as a mouse, or a touch panel attached to the display unit 129 .

[0023] The storage unit 127 stores various measurement conditions used when measuring a sample with the atomic absorption photometer according to this embodiment (for example, information associating a measurement target element with the type of light source used when measuring the element and the wavelength of light detected by the detection unit 143). The storage unit 127 also stores, as information (driving information) required to move the arm 161 to each of the above-mentioned target positions, coordinates of the initial position and each target position in an absolute coordinate system (world coordinate system) that represents the three-dimensional space of the analysis unit 110, or drive amounts of the arm drive unit 163 or the stage drive unit 182 required to move the arm 161 from the initial position to each target position (or from one target position to another).

[0024] The analysis control unit 125 reads out the measurement conditions stored in the memory unit 127 in response to input operations by the analyst, and controls the operation of each unit constituting the measurement unit 140 and autosampler 150 to measure the sample. The measurement data processing unit 126 analyzes the measurement data of the sample acquired by the measurement unit 140 by performing appropriate processing on the measurement data. The analysis control unit 125 and the measurement data processing unit 126 are similar to those provided in conventional atomic absorption photometers, and therefore a detailed description thereof will be omitted.

[0025] As described above, with an atomic absorption spectrophotometer, the chip 153 deteriorates with repeated use, resulting in errors in the amount of sample injected, or the chip 153 becomes clogged, causing previously measured liquid sample to remain in the chip 153 and resulting in contamination. To prevent these problems, analysts must replace the chip 153 at appropriate times. Furthermore, the sample heating unit 141 also deteriorates with repeated use, so analysts must replace the sample heating unit 141 at appropriate times. When replacing the chip 153 or sample heating unit 141, analysts must manually replace the chip 153 or sample heating unit 141, which can result in installation errors, such as the chip 153 being attached to the arm 161 at an angle or the sample heating unit 141 being attached in a misaligned position.

[0026] Therefore, in the atomic absorption spectrophotometer according to this embodiment, after an analyst replaces the tip 153 and / or the sample heating unit 141, the analyst identifies the tip position of the tip 153 and the center position of the sample injection port 144 in the following procedure. The position information acquisition control unit 121 provided in the control / processing unit 120 controls the arm driving unit 163, the stage driving unit 182, the camera 155, and the lighting unit 156 in the process of confirming the tip position of the tip 153 and the center position of the sample injection port 144. The image analysis unit 122 performs predetermined processing on the image captured by the camera 155 and analyzes the processed image to identify the tip position of the tip 153 and the center position of the sample injection port 144 in the image. The position identification unit 123 identifies the actual tip position of the tip 153 and the center position of the sample injection port 144 based on the results of the analysis by the image analysis unit 122 and the output from the photoelectric sensor 170. The teaching information generating section 124 generates teaching information, which will be described later, based on the actual tip position of the tip 153 and the center position of the sample injection port 144 identified by the position identifying section 123 .

[0027] FIG. 5 is a flowchart showing the procedure for identifying the position of the tip of the tip 153 and the center position of the sample injection port 144 in the atomic absorption spectrophotometer according to this embodiment.

[0028] First, when the analyst operates the input unit 128 to instruct the identification of the tip position of the chip 153 and the center position of the sample injection port 144, the arm driving unit 163 moves the arm 161 from a predetermined position (for example, the initial position described above) to the above-mentioned photographing position under the control of the position information acquisition control unit 121 (step 11). As described above, the photographing position is a position where the sample injection port 144 is not within the field of view of the camera 155. Next, the position information acquisition control unit 121 turns on the light 156 to illuminate the area near the tip of the chip 153 while causing the camera 155 to photograph the tip of the chip 153 (step 12), and stores the obtained image in the memory unit 127.

[0029] Next, the position information acquisition control unit 121 moves the arm 161 from the shooting position to the detection position described above using the arm driving unit 163 and the stage driving unit 182, thereby inserting the tip of the chip 153 between the light-projecting unit 171 and the light-receiving unit 172 of the photoelectric sensor 170 (step 13). As a result, the light emitted by the light-projecting unit 171 is partially blocked by the tip of the chip 153 and enters the light-receiving unit 172. The control / processing unit 120 acquires the output of the photoelectric sensor 170 at this time, i.e., an output signal indicating the difference or ratio between the amount of light received in the first region 175 and the amount of light received in the second region 176 of the light-receiving unit 172, as the detection result of the photoelectric sensor 170 (step 14), and stores it in the storage unit 127.

[0030] Next, under the control of the position information acquisition control unit 121, the arm driving unit 163 and the stage driving unit 182 move the arm 161 to the offset position described above (step 15). As described above, the offset position is a position where the sample injection port 144 can be photographed without overlapping with the chip 153. Next, the position information acquisition control unit 121 turns on the light 156 to illuminate the periphery of the sample injection port 144 while causing the camera 155 to photograph the sample injection port 144 (step 16), and stores the obtained image in the memory unit 127.

[0031] Thereafter, the image analysis unit 122 reads out the data of each image acquired in step 12 and step 16 from the storage unit 127, performs processing such as noise removal as necessary, and then determines the tip position of the tip 153 in the image acquired in step 12 and the center position of the sample injection port 144 in the image acquired in step 16 (step 17). Specifically, for example, the contours of the tip 153 and the sample injection port 144 are extracted based on the brightness distribution in the image, and the tip position of the tip 153 and the center position of the sample injection port 144 are determined based on the extracted contour lines. In this case, for example, the center position of the ellipse defined by the contour line of the sample injection port 144 can be determined as the center position of the sample injection port 144. Furthermore, when determining the tip position of chip 153, for example, a center line of chip 153 can be drawn midway between two lines extending vertically on the contour line of chip 153, and the intersection of the part of the contour line connecting the lower ends of the two lines (i.e., the contour line of the tip portion of chip 153) and the center line can be determined as the tip position of the chip.

[0032] Next, the position identifying unit 123 identifies the actual center position of the sample injection port 144 based on the center position of the sample injection port 144 in the image identified in step 17 (step 18). Note that the correspondence between the center position of the sample injection port 144 in the image acquired at the offset position and the actual center position of the sample injection port 144 is determined in advance and stored in the storage unit 127. Here, the actual center position of the sample injection port 144 can be expressed, for example, as the coordinates of the center of the sample injection port 144 in an absolute coordinate system (world coordinate system) that represents the three-dimensional space of the analysis unit 110.

[0033] Next, the position identifying unit 123 identifies the actual tip position of the tip 153 based on the tip position of the tip 153 in the image identified in step 17 and the detection result by the photoelectric sensor 170 acquired in step 14 (step 19). Here, the actual tip position of the tip 153 can be expressed, for example, as the relative position of the tip of the tip 153 with respect to the arm 161, and this relative position can be expressed, for example, as the coordinates of the tip of the tip 153 in a three-dimensional coordinate system (local coordinate system) with a reference point on the arm 161 (for example, the center of the tip attachment portion 154) as the origin.

[0034] For example, if information on the correspondence between the tip position of tip 153 in the image captured at the shooting position and the actual tip position of tip 153 is stored in memory unit 127 in advance, the actual tip position of tip 153 can be estimated based on the tip position of tip 153 in the image identified in step 17 and the information on the correspondence. However, as described above, the image captured by camera 155 does not allow for accurate identification of the tip position of tip 153 in the depth direction of the field of view. For example, as shown in the example of FIG. 2, when the tip of tip 153 is located at point a, point b, or point c on axis A extending from the tip of the lens of camera 155, the tip of tip 153 will all be located at the same pixel in the image. Therefore, it is not possible to identify where the tip of tip 153 is located on axis A from the image alone. Therefore, in the atomic absorption photometer according to this embodiment, the position of the tip of chip 153 is identified based on the detection result by photoelectric sensor 170 acquired in step 14, in addition to the image captured by camera 155. As described above, the detection result by photoelectric sensor 170 (i.e., the output signal of the photoelectric sensor acquired in step 14) reflects the difference or ratio between the amount of light incident on first region 175 of light-receiving unit 172 and the amount of light incident on second region 176. For example, as shown in FIG. 4 , when the center of chip 153 and the boundary line between first region 175 and second region 176 overlap in a front view, the amount of light incident on first region 175 and the amount of light incident on second region 176 are equal. On the other hand, when the center of chip 153 deviates from the boundary line toward second region 176, the amount of light incident on first region 175 becomes larger relative to the amount of light incident on second region 176, and conversely, when the center of chip 153 deviates from the boundary line toward first region 175, the amount of light incident on first region 175 becomes smaller relative to the amount of light incident on second region 176. Therefore, by storing in advance in memory unit 127 the relationship between the difference or ratio in the amount of received light and the relative position in the horizontal direction (arrangement direction of first region 175 and second region 176) between the boundary line between first region 175 and second region 176 and the central axis of chip 153, the position of chip 153 in the horizontal direction can be identified from the output signal of photoelectric sensor 170 acquired in step 14.2 described above, if the position of the tip of the tip 153 in the horizontal direction (the left-right direction in the figure) can be identified, it is possible to identify the position of the tip of the tip 153 on the axis A. In this way, in the atomic absorption spectrophotometer according to this embodiment, when identifying the position of the tip of the tip 153, the detection result by the photoelectric sensor 170 is used in addition to the image acquired by the camera 155, thereby making it possible to identify the position of the tip of the tip 153 with high accuracy. Furthermore, since the photoelectric sensor 170 is less expensive than the camera 155, this embodiment makes it possible to reduce manufacturing costs compared to when multiple cameras are provided in the analysis unit 110.

[0035] After the actual center position of the sample injection inlet 144 and the tip position of the tip 153 have been identified as described above, the teaching information generator 124 generates driving information (teaching information) that takes into account the installation error by correcting the driving information stored in the memory unit 127 based on the information on the actual center position of the sample injection inlet 144 determined in step 18 and the information on the actual tip position of the tip 153 determined in step 19. Specifically, for example, based on the information on the actual positions of the center of the sample injection inlet 144 and the tip of the tip 153 determined above and information on the respective positions of the center of the sample injection inlet 144 and the tip of the tip 153 assumed to be free of the installation error (these positions are referred to as reference positions), the direction and magnitude of the deviation between the reference positions and the actual positions are derived for each of the center position of the sample injection inlet 144 and the tip position of the tip 153. Note that the information on the reference positions is determined in advance and stored in the memory unit 127. Then, the teaching information generation unit 124 corrects the driving information stored in the storage unit 127 based on information on the direction and magnitude of the deviation (positional deviation information), thereby generating teaching information and storing it in the storage unit 127. Then, in subsequent sample measurements, the analysis control unit 125 controls the arm driving unit 163 and the stage driving unit 182 based on the teaching information. This makes it possible to accurately insert the tip of the tip 153 into the center of the sample injection port 144 when introducing the sample collected by the tip 153 into the sample heating unit 141.

[0036] In the above embodiment, the first region 175 and the second region 176 are arranged in the horizontal direction on the light receiving surface of the photoelectric sensor 170, but the arrangement direction of the first region 175 and the second region 176 is not limited to this, and for example, the first region 175 and the second region 176 may be arranged in the vertical direction on the light receiving surface. In this case, the arm 161 is moved to a position where the tip of the chip 153 comes to the boundary between the first region 175 and the second region 176, assuming that there is no positional deviation of the tip of the chip 153. Based on the ratio or difference between the amount of light received by the first region 175 and the amount of light received by the second region 176 at this time, the vertical position of the tip of the chip 153 (i.e., the amount of deviation from the boundary) can be determined. 2, even if the tip position of the tip 153 in the vertical direction can be identified, the tip position of the tip 153 on the axis A can also be identified, so even when a photoelectric sensor 170 having such a configuration is used, it is possible to accurately identify the tip position of the tip 153. Furthermore, a photoelectric sensor 170 having a light-receiving surface divided into two directions (for example, the horizontal direction and the vertical direction) may be used. In this case, information on the tip position of the tip 153 in these two directions can be obtained, so the tip position of the tip 153 can be identified more accurately.

[0037] Furthermore, in the above embodiment, the photoelectric sensor 170 is configured to be provided inside the autosampler 150. Alternatively, as shown in FIG. 6, a photoelectric sensor 270 may be provided above the sample injection port 244 of the measurement unit 240. Note that in FIG. 6, components that are the same as or correspond to those shown in FIG. 1 are assigned reference numerals with the same last two digits. In this case, the photoelectric sensor 270 is disposed so that the first region 275 and the second region 276 of the light receiving unit 272 of the photoelectric sensor 270 are aligned in the extension direction of the arm 261 at the sample injection position (the position indicated by the three-dot chain line in FIG. 6), and the boundary line between the first region 275 and the second region 276 coincides with the central axis of the sample injection port 244 when viewed from a direction perpendicular to the light receiving surface. Then, arm 261 is moved so that the tip of chip 253 is above photoelectric sensor 270, and then arm 261 is lowered so that the tip of chip 253 is between light-emitting portion 271 and light-receiving portion 272 of photoelectric sensor 270. Then, the position of arm 261 is adjusted so that the tip of chip 253 is located directly above sample injection port 244 on an image captured by camera 255 attached to arm 261, and so that the difference between the amount of light received by first region 275 and the amount of light received by second region 276 in photoelectric sensor 270 becomes 0 (or so that the ratio between the amount of light received by first region 275 and the amount of light received by second region 276 becomes 1). This allows the tip of chip 253 to be accurately aligned on the central axis of sample injection port 244.

[0038] Second Embodiment Next, the configuration of an atomic absorption spectrophotometer according to a second embodiment of the present invention will be described with reference to FIGS. 7 and 8. In FIGS. 7 and 8, components that are the same as or correspond to those shown in FIGS. 1 and 2 are designated by reference numerals with the same last two digits, and descriptions thereof will be omitted where appropriate. The atomic absorption spectrophotometer according to this embodiment is similar to the atomic absorption spectrophotometer according to the first embodiment described above, except for the structure of the photoelectric sensor 370 and the method for identifying the leading end position of the tip 353. Therefore, the following description will focus on the differences from the first embodiment, and descriptions of other aspects will be omitted where appropriate.

[0039] In the atomic absorption photometer according to this embodiment, as shown in Fig. 8, the camera 355 is attached to the arm 361 with its optical axis (the central axis of the lens of the camera 355) X facing directly downward. Furthermore, the photoelectric sensor 370 according to this embodiment has a basic configuration that is substantially the same as that shown in Fig. 3, but the light-receiving surface of the light-receiving unit 372 is not divided, and the photoelectric sensor 370 detects whether or not an object is present in front of the light-receiving unit 372 (i.e., between the light-emitting unit 371 and the light-receiving unit 372) based on the amount of light received by the light-receiving unit 372.

[0040] The procedure for identifying the tip position of the tip 353 and the center position of the sample injection port 344 in this embodiment will be described with reference to the flowchart of Fig. 9. First, under the control of the position information acquisition control unit 321, the arm driving unit 363 moves the arm 361 to the same imaging position as in the first embodiment (i.e., the position indicated by the dashed line in Fig. 7) (step 21). Then, the position information acquisition control unit 321 turns on the light 356 and controls the camera 355 to capture an image including the tip of the tip 353 (step 22). Note that the procedure at this time is similar to steps 11 and 12 in the flowchart of Fig. 5, and therefore a detailed description thereof will be omitted.

[0041] Next, under the control of the position information acquisition control unit 321, the arm driving unit 363 and the stage driving unit 382 move the arm 361 to a predetermined position above the photoelectric sensor 370 (the position indicated by the two-dot chain line in FIGS. 7 and 8) (step 23). At this time, the tip of the chip 353 is positioned above the photoelectric sensor 370 (the height of the tip of the lens of the camera 355 at this time is set to the "initial height P ０ After that, the arm 361 is gradually lowered by the arm driving unit 363 until the front end of the tip 353 is detected by the photoelectric sensor 370. １ is stored in the storage unit 327 (step 24).

[0042] Next, under the control of the position information acquisition control unit 321, the arm driving unit 363 and the stage driving unit 382 move the arm 361 to the same offset position as in Embodiment 1 (i.e., a position offset by a predetermined distance in a predetermined direction from the sample injection position indicated by the three-dot chain line in FIG. 7) (step 25). Subsequently, the position information acquisition control unit 321 turns on the light 356 and controls the camera 355 to take an image including the sample injection port 344 (step 26). Note that the procedure at this time is similar to steps 15 and 16 in the flowchart of FIG. 5, and therefore a detailed description thereof will be omitted.

[0043] Thereafter, the image analysis unit 322 identifies the tip position of the tip 353 in the image acquired in step 22 and the center position of the sample injection port 344 in the image acquired in step 26 (step 27). Then, the position identification unit 323 identifies the actual center position of the sample injection port 344 based on the center position of the sample injection port 344 in the image identified by the image analysis unit 322 (step 28). The above steps 27 and 28 are similar to steps 17 and 18 in the flowchart of FIG. 5, and therefore a detailed description thereof will be omitted.

[0044] Next, the position specifying unit 323 determines the tip position of the tip 353 in the image specified in step 27 and the amount of descent L of the arm 361 specified in step 24. １ Based on this, the actual tip position of the tip 353 is identified (step 29). Specifically, the distance L from the initial height P0 to the upper limit of the height that can be detected by the photoelectric sensor 370 is determined in advance. ０ is identified and stored in the storage unit 327, and the distance L ０ From the above-mentioned descent amount L １ By subtracting , the distance from the tip of the lens of the camera 355 to the tip of the tip 353 in the direction of the optical axis X of the camera 355 is determined. Hereinafter, this distance will be referred to as the working distance (WD). As described above, if the tip position of the tip 353 in the image and the WD are known, the actual tip position of the tip 353 can be uniquely determined.

[0045] In addition, the above distance L０ Alternatively, information on the distance (hereinafter referred to as the reference WD) from the tip of the lens of camera 355 to the tip of a predetermined chip 353 (hereinafter referred to as the reference chip) when the reference chip is attached to arm 361 without the above-described positional deviation, and information on the height (hereinafter referred to as the reference arm height) of arm 361 when the tip of the reference chip is detected by photoelectric sensor 370 as arm 361 to which the reference chip is attached is lowered from above photoelectric sensor 370 may be stored in advance in storage unit 327. In this case, in step 24, instead of the amount of lowering, the height of arm 361 when the tip of chip 353 (hereinafter referred to as the target chip) whose position is to be identified is detected by photoelectric sensor 370 is identified, and in step 29, the difference in WD between the reference chip and the target chip is identified from the difference between the reference arm height and the height of arm 361 identified in step 24. Then, the WD for the target chip is identified based on the difference in WD and the reference WD. The relationship between the difference in WD and the difference in height of the arm 361 when the leading end of the tip 353 is detected by the photoelectric sensor 370 is specified in advance and stored in the storage unit 327 .

[0046] In this way, according to the atomic absorption spectrophotometer of this embodiment, in addition to the image acquired by the camera 355, information obtained by detecting the tip of the tip 353 with the photoelectric sensor 370 (i.e., the above-mentioned amount of descent L １ ) the actual tip position of the tip 353 can be accurately determined.

[0047] Thereafter, the teaching information generator 324 generates teaching information by correcting the driving information stored in the memory 327 based on the actual center position of the sample injection port 344 identified in step 28 and the actual tip position of the tip 353 identified in step 29. This process is similar to that described in the first embodiment above, and therefore a detailed description thereof will be omitted.

[0048] In the second embodiment, as shown in FIG. 8, the camera 355 is attached to the arm 361 with its optical axis X facing directly downward. Alternatively, as shown in FIG. 10, the camera 455 may be attached to the arm 461 with its optical axis X tilted relative to the vertical direction. In this figure, components that are the same as or correspond to those shown in FIG. 8 are assigned reference numerals with the same last two digits. When the camera 455 is arranged tilted in this way, the working distance for the chip (target chip 453) whose position is to be specified can be calculated using trigonometric functions. Specifically, for example, as shown in FIG. 10, the working distance for the chip (reference chip 457) attached to the arm 461 without causing the above-mentioned positional deviation can be calculated using WD. ０ , the working distance for the target chip 453 to be located is WD １ θ1 is the angle formed by the plane perpendicular to the optical axis X of the camera 455 and the horizontal plane, θ2 is the angle formed by the optical axis X and axis A, which is the line connecting the tip of the lens of the camera 455 and the tip of the chip 453, and L is the difference in height of the arm 461 when the tips of the reference chip 457 and the target chip 453 are detected by photoelectric sensors (not shown) (i.e., the difference in tip positions of the reference chip 457 and the target chip 453 in the height direction). Then, the difference in working distance between the reference chip 457 and the target chip 453 (i.e., WD １ -WD ０ ) can be expressed as L*(1 / SIN(90°-θ1-θ2))*COSθ2. The value of θ2 is identified from the tip position of the tip 453 in the image identified in step 27 above. Therefore, by storing in advance in a storage unit (not shown) the values ​​of WD0 and θ1, and the height of the arm 461 when the tip of the reference tip 457 is detected by the photoelectric sensor, and also storing in the storage unit the correspondence between the tip position of the tip 453 in the image and the value of θ2, in step 29 above, WD0 can be calculated from these values ​​and the value of the height of the arm 461 when the tip of the target tip 453 is detected by the photoelectric sensor in step 24. １(i.e., the working distance for the target chip 453) can be calculated.

[0049] In the above-mentioned first and second embodiments, the tip positions of the chips 153, 253, 353, and 453 are identified using images acquired at the shooting positions, and the center positions of the sample injection ports 144, 244, and 344 are identified based on images acquired at the offset positions. However, instead, both the tip positions of the chips 153, 253, 353, and 453 and the center positions of the sample injection ports 144, 244, and 344 may be identified based on images acquired at the offset positions. Furthermore, in the first and second embodiments, the cameras 155, 255, 355, 455 are attached to the base end side of the arms 161, 261, 361, 461, and the lights 156, 256, 356, 456 are attached to the tip end side of the arms 161, 261, 361, 461, but the cameras 155, 255, 355, 455 may be attached to the tip end side of the arms 161, 261, 361, 461, and the lights 156, 256, 356, 456 may be attached to the base end side of the arms 161, 261, 361, 461. Furthermore, in the first and second embodiments, the camera 155, 255, 355, 455 and the lighting 156, 256, 356, 456 are attached to the arm 161, 261, 361, 461, but the camera 155, 255, 355, 455 or the lighting 156, 256, 356, 456, or both, may be attached to another location within the analysis unit 110, 210, 310. Furthermore, in the above embodiments, only one camera 155, 255, 355, 455 is provided, but two or more cameras may be provided and the tip of the chip 153, 253, 353, 453 and the sample injection port 144, 244, 344 may be photographed by separate cameras.

[0050] Furthermore, in the above-described first and second embodiments, a transmissive photoelectric sensor 170, 270, 370 is used, and light emitted from the light-emitting portion 171, 271, 371 and partially blocked by the chip 153, 253, 353, 453 is detected by the light-receiving portion 172, 272, 372. However, the present invention is not limited to this, and a reflective photoelectric sensor 170, 270, 370 may be used, and light emitted from the light-emitting portion of the photoelectric sensor and reflected by the chip 153, 253, 353, 453 may be detected by the light-receiving portion of the photoelectric sensor. Alternatively, photoelectric sensors 170, 270, 370 may be of a recursive reflection type having a light-emitting section, a reflecting section, and a light-receiving section, and the light emitted from the light-emitting section of the photoelectric sensor, reflected by the reflecting section, and then partially blocked by chips 153, 253, 353, 453 may be detected by the light-receiving section.

[0051] In the above-described first and second embodiments, the present invention is applied to an autosampler for an atomic absorption spectrophotometer, but the present invention is not limited to this and can also be applied to autosamplers for other analytical devices (for example, liquid chromatographs or gas chromatographs). Furthermore, the liquid collection and injection device according to the present invention can also be used as a device that collects a liquid other than a sample and supplies it to a predetermined location (for example, a device that collects a culture medium containing cells and dispenses it into a predetermined container).

[0052] Experiments conducted to confirm the effects of the present invention will be described with reference to FIGS.

[0053] 11 is a graph showing the height of arm 361 when the tip of tip 353 is detected by photoelectric sensor 370 when arm 361 is lowered from a predetermined height above photoelectric sensor 370 in the atomic absorption spectrophotometer according to embodiment 2 (hereinafter referred to as "arm height at detection"). The vertical axis of the graph shows the distance from the tip of the lens of camera 355 to the tip of tip 353 (i.e., the working distance), and the horizontal axis shows the arm height at detection as a position in the z-axis direction (up and down direction) when the predetermined height is set to 0. As can be seen from the graph, the arm height at detection changes linearly depending on the working distance, and the reproducibility is also good. ２It was confirmed that the value was high at 0.9979.

[0054] 12 and 13 are images showing the results of aligning the tip of the chip 353 with the sample injection port 344 in the atomic absorption spectrophotometer according to the second embodiment. However, these images were taken using a plate with an opening (referred to as an "injection hole" in the figure) of the same dimensions as the sample injection port 344, instead of the sample heating unit 341. FIG. 12 shows the results of aligning the tip of the chip 353 with the sample injection port 344 based solely on the image captured by the camera 355, while FIG. 13 shows the results of aligning the tip of the chip 353 with the sample injection port 344 based on the image captured by the camera 355 and the working distance determined by the method of the second embodiment. As is clear from these figures, it was confirmed that more accurate alignment can be achieved by using the working distance in addition to the image.

[0055] Aspects It will be apparent to those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0056] (Item 1) A liquid collection and injection device according to one aspect of the present invention is a liquid collection and injection device that collects liquid and injects it into a predetermined location, and includes: a tubular tip that aspirates and dispenses liquid with the tip facing downward; a movement mechanism that moves the tip within three-dimensional space; an imaging unit that photographs the tip of the tip; a photoelectric sensor having a light-emitting unit and a light-receiving unit; and a position identification unit that identifies the position of the tip of the tip in three-dimensional space based on the image of the tip of the tip photographed by the imaging unit and detection information obtained by detecting the tip of the tip with the photoelectric sensor.

[0057] (Clause 2) The liquid collection and injection device according to clause 2 is the liquid collection and injection device according to clause 1, wherein the photoelectric sensor has a plurality of regions in which the light receiving surfaces of the light receiving unit are arranged in a predetermined direction, and outputs a detection signal according to the difference or ratio of the amount of light received in each of the plurality of regions, and the position identification unit uses the detection signal of the photoelectric sensor when the tip of the chip is positioned on the path of the light emitted from the light projecting unit as the detection information.

[0058] (Item 3) The liquid collection and injection device according to item 3 is the liquid collection and injection device according to item 1, wherein the position identification unit uses, as the detection information, information on the amount of descent of the tip when the tip is lowered from above the photoelectric sensor to a position where the tip end is detected by the photoelectric sensor.

[0059] (4) The liquid collection and injection device according to 4 is the liquid collection and injection device according to any one of 1 to 3, wherein the liquid collection and injection device is an autosampler for collecting a liquid sample from a sample container and injecting it into a sample injection port provided in a sample heating section of an electrically heated atomic absorption spectrophotometer.

[0060] According to the liquid collection and injection devices of paragraphs 1 to 4, the tip tip position can be determined with high accuracy by utilizing the detection information obtained by detecting the tip of the tip with a photoelectric sensor in addition to the image captured by the imaging unit. Furthermore, since photoelectric sensors are relatively inexpensive, the liquid collection and injection devices of paragraphs 1 to 4 make it possible to determine the tip tip position with high accuracy without significantly increasing manufacturing costs.

[0061] DESCRIPTION OF SYMBOLS 110: Analysis unit 120: Control / processing unit 121: Position information acquisition control unit 122: Image analysis unit 123: Position identification unit 124: Teaching information generation unit 127: Memory unit 140: Measurement unit 141: Sample heating unit 144: Sample injection port 150: Autosampler 151: Sample container 152: Turntable 153: Tip 155: Camera 160: Tip movement mechanism 161: Arm 162: Shaft member 163: Arm drive unit 170: Photoelectric sensor 171: Light projecting unit 172: Light receiving unit 175: First area 176: Second area 181: Stage 182: Stage drive unit

Claims

1. A liquid collection and injection device that collects liquid and injects it into a specified location, comprising: a tubular tip that aspirates and dispenses liquid with the tip facing downwards; a movement mechanism that moves the tip within three-dimensional space; an imaging unit that photographs the tip of the tip; a photoelectric sensor having a light-emitting unit and a light-receiving unit; and a position identification unit that identifies the position of the tip of the tip in three-dimensional space based on the image of the tip tip captured by the imaging unit and detection information obtained by detecting the tip of the tip with the photoelectric sensor.

2. A liquid collection and injection device as described in claim 1, wherein the photoelectric sensor has a plurality of regions in which the light receiving surface of the light receiving unit is arranged in a predetermined direction, and outputs a detection signal corresponding to the difference or ratio of the amount of light received in each of the plurality of regions, and the position identification unit uses the detection signal of the photoelectric sensor when the tip of the tip is positioned on the path of the light emitted from the light projection unit as the detection information.

3. A liquid collection and injection device as described in claim 1, wherein the position identification unit uses as the detection information information on the amount of descent of the tip when the tip is lowered from above the photoelectric sensor to a position where the tip of the tip is detected by the photoelectric sensor.

4. The liquid collection and injection device according to claim 1, which is an autosampler for collecting a liquid sample from a sample container and injecting it into a sample injection port provided in the heating furnace of an electrically heated atomic absorption spectrophotometer.

Images