JPH01127921A - Switching device for spectrophotometer - Google Patents

Abstract

PURPOSE:To decrease the number of parts and to improve the reliability of a switching device by driving a member to be switched by using a stepping motor, providing a stopper and fixing an angle of a motor shaft and determining the direction of a reflected luminous flux. CONSTITUTION:In order to switch light beams from a tungsten lamp 13 used in a visible area and light beams from a heavy hydrogen discharge tube 14 used in an ultraviolet area, a stepping motor 9 is attached. In this state, a current is allowed to flow in order to a winding of the motor 9 only when a reflecting mirror 1 is rotated, and in case a regular reflecting mirror 1 is fixed and used, the current is allowed to flow to only a specific winding. In such a way, a stable point is set at a position of a specific angle as a characteristic of the stepping motor 9, and the motor shaft tries to rotate to this stable point, and by this rotational force, a movable side stopper 12 is pressed against a fixed side stopper 10, the direction of the reflecting mirror 1 is determined, and the direction of the reflected luminous flux can be determined with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spectrophotometer, and particularly to a highly reliable switching device for a spectrophotometer.

[Conventional technology]

In a conventional spectrophotometer, a mechanism using an electromagnet 2, as shown in FIG. 6, was used to move a member to be switched, such as a reflecting mirror 1. In order to rotate the reflecting mirror 1, a pulley 3 is attached to a rotating shaft 4, and a wire 5 wound around the pulley 3 is pulled by an electromagnet 2 to rotate it. That is, when the electromagnet 2 is not activated, it is oriented in one direction due to the elastic force of the spring portion 8 in the wire 5, but when the electromagnet 2 is activated, it is rotated through the pulley 3 against the elastic force of the spring portion 8. The shaft 4 rotates so that the reflecting mirror 1 faces in the other direction. A pair of stoppers 6 are provided to determine the rotation angle. The position of this stopper 6 can be adjusted by means of a screw structure, and the position of the stopper 6 can be adjusted by adjusting the position of the light ray 7 reflected from the reflecting mirror 1.
The direction can be adjusted.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology uses an electromagnet 2° wire 5. Since the spring portion 8 and the pulley 3 are required, there are problems in that the structure is complicated, the number of parts is large, and the reliability is poor.

An object of the present invention is to provide a highly reliable spectrophotometer switching device with a reduced number of parts.

[Means for solving problems]

The present invention provides a switching device for a spectrophotometer that includes a switching device that rotates a member to be switched around an axis to switch the switching device.
Directly connecting the shaft of the switching member to a motor shaft of a stepping motor, providing a movable stopper on the switching member, and providing a fixed stopper with which the movable stopper comes into contact with the switching member at a predetermined regulating position; The movable stopper is pressed against the fixed stopper at a position offset from the torque stability point of the stepping motor.

[Effect]

A stepping motor is used as a drive unit for moving a member to be switched such as a reflecting mirror, and a stopper is provided to stop the rotation of the stepping motor. Furthermore, a predetermined winding of the stepping motor is kept in an energized state, and at this time, by pressing the stopper with the rotational force that causes the motor to rotate to a stable torque point, the angle of the motor shaft is fixed and one reflected light beam is generated. determine the direction of

〔Example〕

First, a case where the member to be switched is a reflecting mirror will be outlined. The easiest way to rotate the reflector 1 is to
As shown in the figure, this is a method in which the reflecting mirror 1 is directly attached to a stepping motor 9 and rotated. By rotating the motor 9, the direction of the light reflected from the reflecting mirror 1 can be changed. However, as it is, it is impossible to accurately set the direction of the reflected light. That is, the accuracy of the step angle of the stepping motor 9 is 0.1
The angle is about 0.01', which is required here. Further, the direction of the light reflected by the reflecting mirror 1 cannot be finely adjusted. In order to make this fine adjustment possible, a fixed stopper 10 is provided, the rotation of the motor shaft 11 is stopped, and the direction of the reflected light beam can be adjusted by moving the position of the stopper 1o. However, if current is applied to several windings of the motor 9 in sequence and the motor 9 continues to rotate, vibrations and noise will occur.

Therefore, current is passed through the windings of the stepping motor 9 in order only when rotating the reflector 1, and when the regular reflector 1 is used fixedly, the current is passed through only specific windings. put. By doing so, a stable point is created at a specific angle position as a characteristic of the stepping motor 9, and the motor shaft 11 attempts to rotate to this stable point. By using this rotational force to press the movable stopper 12 provided on the member on the reflector 1 side against the fixed stopper 10, the direction of the reflector 1 attached to the motor shaft 11 is determined, resulting in a simple structure. The direction of the reflected light beam can be determined with high precision.

Hereinafter, one embodiment of the present invention will be explained in detail with reference to FIG.

This embodiment is an example in which the present invention is applied to a concave mirror that switches the light source of a spectrophotometer. In a spectrophotometer, the light source must be switched depending on the wavelength to be measured. In this example,
Light from a tungsten lamp 13 used in the visible range,
This is a mechanism for switching the light from the deuterium discharge tube 14 used in the ultraviolet region. In FIG. 1, light emitted from a tungsten lamp 13 is reflected by a reflection area 1 and irradiated in six directions. Generally, in a switching device used in a spectrophotometer, in order to switch with high precision, a fixed stopper 10 whose position is adjustable is provided so that the angle of reflected light can be adjusted.

The feature of this embodiment is that a stepping motor 9 with a tip angle of 15° is used to drive the rotation of the axis of the reflecting mirror, and the rotation of the reflecting mirror 1 is fixed at 22.5° with respect to the A direction. It is.

The stepping motor 9 of this embodiment has four excitation states from ■ to ◎. The relationship between each excitation state, rotation angle, and motor generated torque is shown in FIG. Here,■
In the case of phase excitation, the motor 9 has stable points at -30@ and +30'' positions, and is attracted to these positions.Here, the fixed stopper 10 is moved to the 22.5° position. If the reflector 1 is installed nearby, the reflector 1 will always be pressed against the stopper 10. Therefore, by adjusting the position of the stopper 10, the angle of the reflector 1 can be adjusted.

Furthermore, in order to switch from the currently set tungsten lamp 13 to the deuterium discharge tube 14, the excitation phase is switched in the order of ■→■→◎→◎→■. By doing so, it is possible to rotate by 15 degrees in each excitation state and switch the direction.

Furthermore, in this embodiment, in order to reduce the heat generation of the stepping motor 9, the voltage supplied to the stepping motor 9 is kept low except when switching directions. In other words, current is passed only to specific windings.

FIGS. 4 and 5 are a side view and a front view showing another embodiment of the present invention, and this embodiment is used to sequentially automatically switch five filters corresponding to the measurement wavelength range of a spectrophotometer. , is an example to which the present invention is applied. As shown in FIG. 4, a disk 16 on which five filters 15 are installed is fixed to the motor shaft 11 of the stepping motor 9. As shown in FIG.

As shown in FIG. 5, the five filters 15 are 60
They are placed at 6 intervals. Further, a movable stopper 12 is installed on the five-disc plate 16, and a fixed stopper 10 is installed on the motor stand 17.

The feature of this embodiment is that a stepping motor 9 with a step angle of 15 degrees is used, and the movable stopper 12 hits the fixed stopper 10 at a position 20'' from the torque stability point of the motor 9. be.

In the stepping motor 9 of this embodiment, there are four excitation states from ■ to ◎, as shown in the third @. In the case of phase excitation, the motor 9 has stable points at -30'' and +30'' positions. Therefore, no matter where the filter 15 is located, the stepping motor 9 rotates in six directions by a preset number of pulses, the movable stopper 12 flashes several times on the fixed stopper 10, and the stepping motor 9 stops. . Since this stopped state is subjected to phase excitation, the movable stopper 12 is reversed by 20 degrees and reaches the stable point 1.
Stops at 8. Since the filter 15 is installed at a position 60" from this stable point 18, the filter 15 always stops at the initial position 19 with high precision. After initialization is completed, the excitation phase of the stepping motor 9 is switched to the third
By switching in the order of →■→◎→◎→■ in the figure, the motor 9 will rotate by 15 degrees in each excitation state, so switching of each filter can be automatically performed sequentially by sending 4 pulses. Can be done. In Figure 5, 2
0 indicates luminous flux.

〔Effect of the invention〕

According to the present invention, since a stepping motor is used,
A highly reliable light beam direction switching device with a reduced number of parts can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a plan view of one embodiment of the present invention, FIG. 2 is a side view of the same, FIG. 3 is a diagram showing the relationship between the rotation angle of the stepping motor and the motor torque, and FIG. 4 is another embodiment of the present invention. FIG. 5 is a side view of the example, FIG. 5 is a front view thereof, and FIG. 6 is a perspective view of a conventional example. DESCRIPTION OF SYMBOLS 1... Reflector (switched member), 9... Stepping motor, 1o... Fixed side stopper, 11... Motor shaft, 12... Movable side stopper, 15... Filter,
16...disk, 18...stable point.

Claims (1)

[Claims] 1. In a spectrophotometer switching device equipped with a switching device that rotates a member to be switched around a shaft, the shaft of the member to be switched is directly connected to a motor shaft of a stepping motor, and the member to be switched is connected directly to a motor shaft of a stepping motor. A movable stopper is provided on the switching member, and a fixed stopper is provided with which the movable stopper comes into contact with the switched member at a predetermined regulating position, and the movable stopper causes the fixed stopper to deviate from the stable torque point of the stepping motor. A switching device for a spectrophotometer, which is characterized by pressure contact at a fixed position. 2. The switching device for a spectrophotometer according to claim 1, wherein two fixed stoppers are provided, and the movable stopper reciprocates between the two fixed stoppers. 3. A switching device for a spectrophotometer according to claim 1, in which the number of fixed stoppers is one, and the initial position of the member to be switched is determined based on the contact point of both stoppers. 4. A switching device for a spectrophotometer according to claim 2, which reduces the voltage supplied to the stepping motor when both stoppers are in contact with each other.