JP2004012164A - Spectrophotometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch two photodetectors at low cost, at a high-speed and in a high positional reproducibility. <P>SOLUTION: A pin 18 which is integrally rotated with a spindle of a motor 15 is inserted into an elongated hole 22 of a connection plate 21 which is capable of freely rotating around a shaft 19 as the center. A pin 24 provided vertically on a carriage 3 on which the photodetectors 4 and 7 are disposed is inserted into a cutout 23 of the connection plate 21. The connection plate 21 is biased by a spring 25 toward both sides, in which the boundary is approximately at the center of the rotational range. When the motor 15 is rotated in the clockwise direction, from the state in which the carriage 3 abuts on a position regulation pin 10, the pin 18 rotates the connection plate 21 against the biasing force, and when passing over the boundary, the direction of the energizing force is reversed, and the connection plate 21 is further rotated. Thus, the carriage 3 is moved. Before abutting on a position regulation pin 11, the pin 18 abuts on the rear part of the elongated hole 22, and suppresses the moving velocity of the connection plate 21 against the biasing force. Accordingly, the impact sound of the position regulation pin 11 with the carriage 3 can be suppressed, without deteriorating the high-speed movement. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spectrophotometer such as a visible ultraviolet spectrophotometer, and more particularly, to a spectrophotometer provided with a plurality of photodetectors and light sources that can be switched.
[0002]
[Prior art]
There is known a spectrophotometer which is provided with a switchable photodetector having a detection characteristic according to a wavelength to be used. FIG. 5 is a schematic configuration diagram of such a spectrophotometer. In FIG. 5, light emitted from a light source 31 is introduced into a monochromator 32, and monochromatic light having a predetermined wavelength is extracted and irradiated on a sample 33. The sample 33 has a specific transmission characteristic or reflection characteristic, and the measurement light, which is transmission light or reflection light reflecting the characteristic, is supplied to a photodetector whose position is mechanically changed by a photodetector switching mechanism 34. It is incident on either 4 or 7. The photodetector switching drive unit 35 drives the photodetector switching mechanism 34 under the control of a control unit (not shown). The light receiving signal from the photodetector 4 or 7 is input to the signal processing unit 36, where the arithmetic processing and the like are executed, whereby the transmittance and the reflectance of the sample 33 are calculated.
[0003]
FIG. 6 and FIG. 7 are conventional schematic configuration diagrams of such a photodetector switching mechanism 34, wherein (A) is a top view and (B) is a longitudinal sectional view of a main part.
[0004]
In the example of FIG. 6, a fan-shaped plate 43 is fixed to an output shaft 42 of a motor 41 with a gear head, and two types of photodetectors 4 and 7 are externally mounted on a coaxial circumference of the upper surface thereof using holders 44 and 45, respectively. Installed in the correct orientation. Since the fan-shaped plate 43 is directly rotated by the rotation of the output shaft 42, the reproducibility of the positions (horizontal positions) of the photodetectors 4 and 7 at the time of switching depends on the reduction ratio of the gear head of the motor 41. I do. Therefore, in order to obtain high position reproducibility, the mechanical accuracy of the gear head needs to be high, and the number of components is small, but an expensive motor is required.
[0005]
On the other hand, in the example of FIG. 7, a disk body 52 having a guide pin 53 protruding is fixed to the output shaft 42 of the motor 41 with a gear head. The fan-shaped plate 55 is rotatable about a shaft 54, and the guide pin 53 is inserted into an elongated hole 56 formed to extend substantially in the radial direction. When the guide pin 53 rotates around the output shaft 42 by the rotation of the output shaft 42, a part of the inner wall surface of the elongated hole 56 receives a force via the guide pin 53, whereby the fan-shaped body plate 55 rotates. . Also in this configuration, the mechanical accuracy of the gear head is required to obtain high position reproducibility, as in the example of FIG.
[0006]
[Problems to be solved by the invention]
The conventional photodetector switching mechanism has the following several problems in addition to the high cost.
[0007]
That is, in each of the above-described conventional photodetector switching mechanisms 34, the fixed positions of the photodetectors 4 and 7 are separated from the rotation shaft (the output shaft 42 in FIG. 6 and the shaft 54 in FIG. 7). Then, it is d1 and in the example of FIG. 7, it is d2. For this reason, for example, the effects of bending of the fan-shaped plates 43 and 55 and backlash in the vertical direction due to tightening or the like when the holders 44 and 45 are attached cannot be ignored, and the luminous flux of the measuring light is detected by the It becomes difficult to perform adjustment to irradiate the center of the light receiving surface. For example, the size of the light beam of the measurement light immediately before entering the photodetector is about 1.5 × 2 mm, whereas the size of the light receiving surface of the photodetector is not as large as φ3 mm. Therefore, if the deviation of the vertical position adjustment is large, there is a possibility that a part of the light beam may fall off the light receiving surface.
[0008]
In the above configuration, if the radius of the fan-shaped plates 43 and 55 is reduced and the distance from the rotation center to the fixed position of the photodetectors 4 and 7 is shortened, the influence of the above-described bending and backlash can be reduced. it can. However, in this case, the required rotation angle of the fan-shaped plates 43 and 55 at the time of switching becomes large, and the time required for switching becomes long, which is not practical. Furthermore, in order to ensure the reproducibility of the position in the horizontal direction, it is conceivable to increase the reduction ratio of the gear of the motor 41, but this is also not preferable because the time required for switching becomes long.
[0009]
Some spectrophotometers are provided not with a photodetector but with two light sources having different emission wavelengths so as to be switchable, but it goes without saying that the same problem occurs in such a spectrophotometer.
[0010]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a spectrophotometer including a plurality of photodetectors and light sources which can be switched, and which has a relatively low cost and a high cost. An object of the present invention is to provide a spectrophotometer capable of achieving position reproducibility and high-speed switching. It is another object of the present invention to provide a spectrophotometer which does not generate a loud noise when a photodetector or a light source is switched.
[0011]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problem. An object of the present invention is to provide two optical members of the same kind, such as a light source and a photodetector, to advance one of the two optical members on a predetermined optical path and to retract the other. And a switching means for mechanically switching the optical member by means of a spectrophotometer comprising:
a) linear guide means;
b) a carriage on which two first and second optical members are mounted and which can reciprocate linearly along the guide means;
c) a first position corresponding to the selection of the first optical member, and a selection of the second optical member by being provided on both sides of the movable table in the extending direction of the guide means and abutting the movable table. Position regulating means for regulating the position of the movable table to a second position corresponding to
d) a rotation driving means for driving a driving shaft provided with the engagement portion,
e) an engaged portion that is rotatable about an axis substantially coaxial with the drive shaft and engages with the engaging portion so as to freely rotate within a predetermined angle range with respect to the engaging portion; A rotating body having a power transmission unit for moving the movable table in a direction corresponding to the rotating direction along with the rotating,
f) biasing means for biasing the rotating body in a direction away from the boundary on both sides of the boundary at a point where the rotating body is at a predetermined angular position;
It is characterized by having.
[0012]
Here, the optical member may be a photodetector that receives the measurement light or a light source that emits light that is a source of the measurement light.
[0013]
Further, in the spectrophotometer according to the present invention, when the moving table is moving from the first position to the second position, or vice versa, at least immediately before the moving table contacts the position regulating means, It is preferable that a configuration is provided that includes a control unit that controls the rotation driving unit so as to reduce the rotational speed of the drive shaft and reduce the impact at the time of contact.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
In the spectrophotometer according to the present invention, for example, switching from the state where the first optical member is currently selected (that is, the first optical member is located on the predetermined optical path) to the second optical member is performed (that is, the switching is performed) When the second optical member advances on a predetermined optical path instead of the first optical member), the switching means operates as follows.
[0015]
That is, in the state where the first optical member is selected, the rotating body is urged in the predetermined rotation direction by the urging means, and the movable table abuts on the position regulating means by the force received via the power transmission unit. It is in one position. In this state, when the drive shaft is rotated by the rotation drive means in a direction opposite to the predetermined rotation direction by the urging, the rotational power of the drive shaft is transmitted to the rotating body by the engagement between the engagement portion and the engaged portion. The rotating body rotates in the same direction as the drive shaft against the urging force. Thereby, the carriage starts moving away from the first position toward the second position.
[0016]
When the rotating body reaches and exceeds the predetermined angular position, which is the boundary, the direction in which the urging force is applied by the urging means is reversed and becomes the same as the rotating direction of the rotating body. Therefore, the rotating body is instantaneously rotated by the urging force of the urging means instead of the force from the drive shaft, and the movement of the movable table is promoted. At this time, since the rotating body rotates faster than the drive shaft, the engagement between the engaging portion and the engaged portion is temporarily released, but the angle of free rotation of the rotating body with respect to the engaging portion is limited. Therefore, when the rotating body rotates by that angle, the engaging portion and the engaged portion are engaged again.
[0017]
However, unlike the previous engagement, the rotating body is urged by the urging means in the rotating direction at that time, so that the rotating body is moved from the drive shaft by the engagement between the engaging portion and the engaged portion. Is applied in a direction opposite to the urging force, that is, in a direction opposite to the rotating direction of the rotating body. Therefore, at this time, the engagement between the engaging portion and the engaged portion acts to suppress the rotation of the rotating body due to the urging force, and the rotation speed of the rotating body is increased despite the urging force. It becomes the same as the rotation speed of the drive shaft. Then, when the rotating body reaches the predetermined position with the rotation of the drive shaft, the movable table abuts on the position regulating means and stays at the second position, and the switching from the first optical member to the second optical member is completed. . Therefore, as described above, if the rotational speed of the drive shaft is reduced at least immediately before the moving table contacts the position restricting means, the impact when the moving table contacts the position restricting means can be small.
[0018]
When the second optical member is switched to the first optical member, the direction of rotation of the drive shaft and the rotating body and the direction of movement of the movable table are reversed, but the basic operation is the same as described above.
[0019]
【The invention's effect】
In the spectrophotometer according to the present invention, the movable table is slidably held by the guide means, and the two optical members can be positioned above the guide means. Therefore, even if the movable table moves when the optical member is switched, the optical member does not move up and down or rattle, so that the positional accuracy of the optical member in the vertical direction can be easily increased. Further, since the first position and the second position are determined by bringing the movable table into contact with the position regulating means, the reproducibility of the position in the horizontal direction is very high.
[0020]
Furthermore, since deceleration by the gear head is unnecessary, an inexpensive motor without a gear head can be used. In addition, since the position of the movable table, that is, the position of the optical member can be determined by the position regulating means, there is no need to provide a position sensor for detecting the rotational position even when a stepping motor is used as the motor. Therefore, the cost can be suppressed while improving the position reproducibility as compared with the related art.
[0021]
Further, since a part of the movement of the movable table is achieved by the urging force of the urging means such as a spring, the moving speed during the period is usually very high, and the time required for switching the optical members can be shortened. it can. Furthermore, when the moving table contacts the position regulating means, the urging force by the urging means is suppressed and the moving table contacts the moving speed corresponding to the rotation speed of the rotation driving means. By reducing the speed, the impact noise generated at the time of abutment can be reduced even if both the moving table and the position regulating means are made of metal.
[0022]
【Example】
Hereinafter, an embodiment of the spectrophotometer according to the present invention will be described with reference to the drawings. 1 and 2 are top views showing the configuration of the main part of the photodetector switching mechanism in the spectrophotometer according to the present embodiment, FIG. 3 is a longitudinal sectional view of the main part, and FIG. 4 is the operation of this photodetector switching mechanism. FIG.
[0023]
In this photodetector switching mechanism, a linear guide 2 is fixed on the base 1 as the guide means, and the linear guide 2 is reciprocally movable along the linear guide 2 on the linear guide 2. Carriage 3 is provided. On the upper surface of the carriage 3, a first photodetector holder 5 for holding a PbS detector as a first photodetector 4 and a second photodetector holder for holding an InGaAs detector as a second photodetector 7. The detector holder 8 is fixed with screws 6 and 9, respectively. On the base 1, first and second two positioning pins 10 and 11 are erected as the above-mentioned position regulating means so as to sandwich the carriage 3 in the extending direction of the linear guide 2. The carriage 3 is positioned by bringing the carriage 3 into contact with 10 and 11. Further, on the upper surface of the base 1 on the left side of the linear guide 2, first and second two reflecting mirrors 12, 13 are fixed so that the position and the angle can be finely adjusted. As shown in FIGS. 1 and 2, the measuring mirror S and the reference light R arriving from the right are condensed at the same position (that is, the light receiving surface of the selected photodetector 4 or 7). , 13 are adjusted.
[0024]
An opening 14 is provided in the base 1 on the right side of the linear guide 2 so as to penetrate vertically, and a stepping motor 15 as a rotation driving means is provided on a lower surface of the opening 14 so that the motor shaft 16 projects upward from the opening 14. It is fixed in the state where it was. A substantially cylindrical boss 17 having a guide pin 18 erected thereon is fixed to the upper portion of the motor shaft 16, and the upper portion of the boss 17 is connected to a shaft 19 which is coaxial with the motor shaft 16 via a bearing 20 with a flange. A rotatable connecting plate 21 is mounted as the rotating body. An elliptical elongated hole 22 is formed at a predetermined position of the connecting plate 21, and the guide pin 18 is inserted into the elongated hole 22. Therefore, the guide pin 18 functions as the engaging portion, and the elongated hole 22 functions as the engaged portion. A notch 23 extending in the radial direction is formed at the outer edge of the connecting plate 21, and a cylindrical pin 24 erected on the upper surface of the carriage 3 is inserted movably in the notch 23. Therefore, the notch 23 functions as the power transmission unit in cooperation with the pin 24. Further, a tension coil spring 25 is provided between the movable post 26 on the upper surface of the connecting plate 21 and the fixed post 27 provided on the base 1 as the urging means.
[0025]
In the above configuration, the long hole 22 of the connecting plate 21 limits the moving range of the guide pin 18, and when the boss 17 rotates by driving the motor 15, the guide pin 18 comes into contact with the edge of the long hole 22. By pushing the lever, rotational power is applied to the connecting plate 21. Further, when the connecting plate 21 rotates, the peripheral portion of the notch 23 presses the pin 24, so that the carriage 3 moves linearly along the linear guide 2 by the force. The range of the reciprocating movement of the carriage 3 is determined by the positions at which the front end surface and the rear end surface of the carriage 3 abut on the first and second positioning pins 10 and 11, thereby restricting the rotation range of the connecting plate 21. . Further, while the connecting plate 21 rotates about the shaft 19, the fixed end (fixed post 27) of the coil spring 25 is located farther from the shaft 19 when viewed from the moving end (moving post 26). For this reason, the coil spring 25 extends the most at substantially the center of the rotation range of the connecting plate 21, and applies a compressive urging force to the connecting plate 21 in either the right or left rotation direction from there.
[0026]
Next, a switching operation of the photodetector in the photodetector switching mechanism having the above configuration will be described with reference to FIG.
Now, it is assumed that the initial positions of the carriage 3, the boss 17, and the connecting plate 21 are the positions depicted in FIG. At this time, the connecting plate 21 is urged in the counterclockwise direction by the compressive force of the coil spring 25, whereby the carriage 3 is urged in the forward direction and is stopped at the position where it comes into contact with the first positioning pin 10. ing. This state is the same as that of FIG. 2, and the light reflected by the reflecting mirrors 12 and 13 is introduced to the first photodetector 4.
[0027]
When switching from the first photodetector 4 to the second photodetector 7 is instructed, a control signal for driving the motor 15 to rotate clockwise is input to the motor 15. As a result, the motor shaft 16 rotates and the boss 17 also rotates clockwise, but the guide pin 18 first moves in the circumferential direction inside the elongated hole 22, so that the guide pin 18 , The connecting plate 21 and the carriage 3 remain stationary. For example, the angle corresponding to the movement of the guide pin 18 in the elongated hole 22 is about 13.5 °.
[0028]
As described above, when the guide pin 18 moves and comes into contact with the edge of the elongated hole 22 in the traveling direction (see FIG. 4B), the guide pin 18 rotates around the shaft 19 in the clockwise direction. Start pressing. At this time, the connecting plate 21 receives a counterclockwise force due to the compressive force of the coil spring 25, but the rotational power of the motor 15 rotates the connecting plate 21 clockwise against the urging force of the spring 25. Let it. When the connecting plate 21 rotates clockwise in this manner, the carriage 3 moves in the depth direction. When the guide pin 18 rotates about 35.5 °, the coil spring 25 extends most (see FIG. 4C). Until then, the connecting plate 21 is constantly subjected to a counterclockwise force by the coil spring 25.
[0029]
When the connecting plate 21 passes through the rotational position where the coil spring 25 extends most, the compressive force of the coil spring 25 acts to rotate the connecting plate 21 clockwise. Therefore, the connecting plate 21 is instantaneously largely rotated clockwise, for example, about 19 ° by the urging force of the coil spring 25 (see FIG. 4D). At this time, since the rotation speed of the connection plate 21 is much higher than the rotation speed of the motor 15, the guide pin 18 abuts on the rearward edge of the elongated hole 22 of the connection plate 21. The rotation is temporarily stopped. Although a small impact sound is generated at the time of this contact, the impact sound is small since the rotation stroke of the connecting plate 21 is small.
[0030]
Further, the motor 15 is driven in the clockwise direction, so that the guide pin 18 rotates at the same speed as the motor shaft 16. Since the guide pin 18 prevents the rotation of the connecting plate 21 by the coil spring 25, the connecting plate 21 also rotates clockwise in accordance with the rotation of the guide pin 18. When the carriage 3 moves in the depth direction according to the rotation of the connecting plate 21 and comes into contact with the second positioning pin 11, the rotation of the connecting plate 21 stops (see FIG. 4E). Then, when the motor 15 is further driven to rotate, the guide pin 18 moves inside the elongated hole 22 and hits the edge in the traveling direction (see FIG. 4F). This state is the same as that in FIG. 1, and the light reflected by the reflecting mirrors 12 and 13 is introduced to the second photodetector 7.
[0031]
As described above, when the carriage 3 moves from the front side to the back side, the carriage 3 moves at a high speed in the middle due to the urging force of the coil spring 25, but its speed becomes slow before colliding with the second positioning pin 11, and the motor 15 Abuts on the second positioning pin 11 at a slow speed corresponding to the rotation speed of. Therefore, it is possible to avoid generating a loud collision sound at the time of contact.
[0032]
In the above description, the operation is performed at the time of switching from the first photodetector 4 to the second photodetector 7. However, it is apparent that the same operation is performed at the time of reverse switching.
Although the above embodiment is an example in which the present invention is applied to switching of a photodetector, a similar configuration can be used for switching other optical members of a spectrophotometer, specifically, switching of a light source. Is natural.
[0033]
The above embodiment is an example, and it is apparent that changes and modifications can be made as appropriate within the scope of the present invention.
[Brief description of the drawings]
FIG. 1 is a top view showing a configuration of a main part of a photodetector switching mechanism in one embodiment of a spectrophotometer according to the present invention.
FIG. 2 is a top view illustrating a configuration of a main part of a photodetector switching mechanism according to the embodiment.
FIG. 3 is a vertical cross-sectional view showing a configuration of a main part of a photodetector switching mechanism in the present embodiment.
FIG. 4 is an explanatory diagram of the operation of the photodetector switching mechanism in the embodiment.
FIG. 5 is a schematic configuration diagram of a spectrophotometer provided with a switchable photodetector.
FIG. 6 is a top view and a vertical sectional view showing a schematic configuration of a conventional photodetector switching mechanism.
FIG. 7 is a top view and a vertical sectional view showing a schematic configuration of a conventional photodetector switching mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Base 2 ... Linear guide 3 ... Carriage 4 ... First photodetector 5 ... First photodetector holder 6, 9 ... Screw 7 ... Second photodetector 8 ... Second detector holder 10, 11 ... Position regulation Pins 12, 13 Reflecting mirror 14 Opening 15 Stepping motor 16 Motor shaft 17 Boss 18 Guide pin 19 Shaft 20 Flanged bearing 21 Connection plate 22 Slot 23 Notch 24 Pin 25 Coil Spring 26: Moving post 27: Fixed post

Claims (4)

A spectrophotometer comprising: two optical members of the same type; and switching means for mechanically switching the optical members by advancing one of the two optical members onto a predetermined optical path and retracting the other. The switching means
a) linear guide means;
b) a carriage on which two first and second optical members are mounted and which can reciprocate linearly along the guide means;
c) a first position corresponding to the selection of the first optical member, and a selection of the second optical member by being provided on both sides of the movable table in the extending direction of the guide means and abutting the movable table. Position regulating means for regulating the position of the movable table to a second position corresponding to
d) a rotation driving means for driving a driving shaft provided with the engagement portion,
e) an engaged portion that is rotatable about an axis substantially coaxial with the drive shaft and engages with the engaging portion so as to freely rotate within a predetermined angle range with respect to the engaging portion; A rotating body having a power transmission unit for moving the movable table in a direction corresponding to the rotating direction along with the rotating,
f) biasing means for biasing the rotating body in a direction away from the boundary on both sides of the boundary at a point where the rotating body is at a predetermined angular position;
A spectrophotometer comprising: The spectrophotometer according to claim 1, wherein the optical member is a photodetector that receives measurement light. The spectrophotometer according to claim 1, wherein the optical member is a light source that emits light that is a source of measurement light. When the movable table is moving from the first position to the second position, or vice versa, at least immediately before the movable table comes into contact with the position regulating means, the rotational speed of the drive shaft is reduced and the contact is made. The spectrophotometer according to any one of claims 1 to 3, further comprising control means for controlling the rotation driving means so as to reduce a shock at the time.

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