JPS6026169B2 - Spectrophotometer filter switching mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter switching mechanism for a spectrophotometer, particularly an infrared spectrophotometer.

In an infrared spectrophotometer, a diffraction grating is used to obtain monochromatic light over a wide wavelength range, but to block higher-order light, multiple interference filters are sequentially switched and inserted into the optical path.

Conventional filter switching mechanisms use a combination of electrical circuits and mechanical systems, making them relatively complex and expensive. Infrared spectrophotometers can be classified into the following three types depending on the wavelength range used.
They can be classified into different types, and the number of high-order light blocking filters used also differs.

Popular type: 4000-650 skin - 1 with 3 filters.
Standard type...4000 to 40 ratio Ne-1 with 4 filters.
Luxury type: 4000-200 or 2550 skin-1 with 5-6 filters. FIG. 1 is a perspective view illustrating a conventional filter switching mechanism.

This switching mechanism shows an example using five interference filters, and the five interference filters 5 to 9 have a trapezoidal shape and are attached around one disc-shaped filter base 4. ing.
Furthermore, five microswitches 10 to 14 are arranged around the switch cam 3 in contact with it. The filter stand and the switch cam 3 are attached to the drive shaft 2 of the filter drive motor 1 in the same phase. Therefore, when the drive shaft 2 rotates once in the direction of the arrow, the five filters are sequentially inserted into the optical path, but the rotation of the drive motor stops each time the contacts of the microswitches 10 to 14 enter the notches of the switch cam 3. do. FIG. 2 is an explanatory diagram of a starting means for the drive motor shown in FIG. 1. In addition to the filter switching mechanism shown in FIG. 1, there is a wave number drive shaft 23 which is constantly rotating during wavelength scanning, and switch cams 19 to 22 are mounted on this shaft at varying mounting angles. Also, this switch cam 19~
Microswitches 15 to 18 are installed in contact with each of the microswitches 22 . FIG. 3 is an electrical circuit diagram used with the filter sliding mechanism shown in FIG.
The same members as those shown in the drawings are given the same reference numerals.

The filter switching operation will be explained mainly with reference to FIG. first,
When the measurement by the filter 5 shown in FIG. 1 is completed and the scanning of the next wave number range is to be started, the switch cam 19 shown in FIG. When the drive motor rotates, the contact of the microswitch 13 shown in FIG. 1 falls into the notch of the switch cam 3 and the microswitch 13 is turned off, the rotation of the drive motor 1 is stopped and the filter 6 is inserted into the optical path. . Next, when finishing the measurement using the filter 6 and moving on to scanning the next wave of light, use the same machine and switch cam 2.
0 connects the microswitch 16 and rotates the drive motor 1 to put the filter into the optical path.

When the measurement of the wave number range light handled by the filter 7 is completed, the contact of the microswitch 12 falls into the notch of the switch cam 3, the electric circuit is cut off, and the drive motor is stopped.
As described above, the conventional filter switching means is complicated and expensive, combining mechanical parts with electric circuits.

Further, it takes a lot of time to adjust the filter switching mechanism, and there is a drawback that reliability is lacking in terms of the life of the microswitch. The purpose of the present invention is to provide a new filter switching mechanism that is inexpensive, simple, and highly reliable, and is characterized by the fact that it employs a filter switching mechanism that uses only a cam and a bar without using an electric circuit system. It is in. FIG. 4 is a diagram illustrating a filter switching mechanism which is an embodiment of the present invention, and the same members as in FIG. 1 are given the same reference numerals.

The filter part is the same, but there is a pulley 28 on the drive shaft 2.
is attached and the drive system 30 is wound around it. One end of this drive system 30 is attached to a lever 25 having a fulcrum 27, and the other end is attached to a point C 27 of the lever 25 via a tension spring 26.
It is installed on the opposite side across the board. A roller 26 is provided at the end of the lever 25 on the side where the tension spring 29 is stopped, and the roller 26 is always brought into contact with the cam surface of the filter switching cam 24. This filter switching cam 24 has 5
It has a stepped cam height and was made for use with five filters. To explain the operation of the filter switching mechanism configured as above, when the wave number drive roller 23 rotates and the roller 26 falls to the next force height, the lever 25 is pulled by the tension spring 29 about the fulcrum 27. The filter 6 is inserted into the optical path by rotating the drive shaft 2 by a certain angle.

As the wave number scanning progresses and the roller 26 falls to the next cam height of the filter switching cam, the filter 7 is similarly inserted into the optical path. In this way, five filters are inserted into the optical path one after another to complete the series of scanning of the wide-wave normal school. At this time, the filter and filter switching cam positions are returned to their initial states in preparation for the next measurement. The filter cutter depth mechanism of the following embodiments does not require an electrical system and can be operated only by a cam and a bar, so the mechanism has the advantage of being simple, reliable, and extremely inexpensive.

FIG. 5a is a plan view of a filter switching cam used in a filter switching mechanism according to another embodiment of the present invention, in which four filters are used, that is, for use in a standard infrared spectrophotometer. It is something.

An auxiliary disk 31 having a radius equal to the height of the fourth stage cam is attached in close contact with the filter switching cam 24. If the length of the roller 26 is set so that it also contacts this disc, the range of the height of the fifth stage cam shown by the broken line is eliminated, and it can be used as a four-sheet filter. Of course, the angular range of each cam height must match the mounting angle of the filter. FIG. 5b is a plan view of an auxiliary disk used in a filter switching cam for a three-filter filter, which is a modification of this embodiment.

Since the radius of this auxiliary disk 32 is equal to the height of the third stage cam in FIG.
That is, it can be used as a filter switching cam for a popular type infrared spectrophotometer. By adding an auxiliary disk to the filter switching cam for high-end models, the filter switching cam of this example can be easily used for spectrophotometers with different filter numbers, and has the effect of improving mass productivity. It is occurring.

As described above, the filter switching mechanism of the present invention has the remarkable effect that it is possible to construct a simple, inexpensive, and highly reliable filter switching mechanism for a spectrophotometer without using any electrical system using microswitches or the like.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating a conventional filter stamp removal mechanism;
FIG. 2 is a diagram illustrating the starting means for the drive motor shown in FIG. 1;
3 is an electric circuit diagram used together with the filter cutting mechanism shown in FIG. 1, FIG. 4 is a diagram illustrating a filter cutting mechanism according to an embodiment of the present invention, and FIG. FIG. 5b is a plan view of a filter switching cam used in the filter switching mechanism according to the embodiment, and FIG. be. 2... Drive shaft, 4... Filter stand, 5-9... Filter stand, 23... Wave number drive shaft, 24... Filter switching cam,
25... lever, 26... roller, 27... fulcrum, 28... pulley, 29... tension spring, 30... drive system, 31, 32... auxiliary disc. Multiple diagrams, multiple 2 diagrams, multiple J diagrams, multiple 4 diagrams, multiple diagrams

Claims (1)

[Claims] 1. A plurality of filters with different characteristics for blocking high-order diffraction light are attached around a filter stand attached to a rotatable drive shaft, and the plurality of filters are sequentially inserted into the optical path to generate a series of wide-range beams. A filter switching mechanism for a spectrophotometer that uses a diffraction grating for extracting wavenumber light as a dispersion element includes a pulley attached to the drive shaft, a drive system that includes a tension spring wound around this pulley, and this drive system. A lever with both ends attached to both sides of a fulcrum, a filter switching cam having a plurality of cam heights that contact rollers provided at the tip of the lever in stages, and a wave number drive shaft that rotates this filter switching cam. A filter switching mechanism for a spectrophotometer, characterized in that the filters are sequentially inserted into an optical path by rotating the wavenumber drive shaft and performing wavenumber scanning. 2. The filter switching mechanism for a spectrophotometer according to claim 1, wherein the filter switching cam is a filter switching cam having a cam surface with different cam heights in stages equal to the number of filters. 3 The filter switching cam is a filter in which a circular plate having a radius equal to the height of the cam surface of the number of stages equal to the number of filters is attached to the filter switching cam having a cam surface with different cam heights in stages greater than the number of filters. The spectrophotometer filter switching mechanism according to claim 1 or 2, which is a switching cam.