JPS635295A - Positioning device in rotary motion mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a positioning device for positioning a drive mechanism that performs rotational motion.

(Prior Art) Conventionally, for example, in an automatic chemical analyzer, a plurality of reaction tubes are arranged at predetermined positions and photometric analysis is performed while rotating them.

In such devices, the mechanical part that performs rotational movement is usually driven by a pulse motor. Then, pulses are generated periodically, and positioning is performed by controlling rotation based on the number of pulses.

Other than this method, for example, count control using a photocoupler and a cut plate is used. In other words, a cut plate that blocks light is provided in a rotationally driven drive mechanism, and positioning is performed by counting the passage of the cut plate with a photo coupler as it rotates. The method of doing so is used.

However, in the above-mentioned positioning device, for example, in the method of controlling rotation based on the number of pulses, the repeatability of positioning decreases due to errors in the generated pulses, and since only the relative position can be detected, it is difficult to correct operational errors. be. On the other hand, positioning using a combination of a cut plate and a photocoupler has the problem of large detection errors and poor reproducibility because the cut plate itself has a width.

(Problems to be Solved by the Invention) As described above, in conventional positioning devices, the method of controlling rotation from the number of pulses reduces the reproducibility of positioning due to errors in the generated pulses, and only the relative position is detected. Therefore, it is difficult to correct operational errors. On the other hand, positioning using a combination of a cut plate and a photocoupler has the problem of large detection errors and poor reproducibility because the cut plate itself has a width. Due to such problems, for example, the above-mentioned automatic chemical analyzer to which a conventional positioning device is applied has disadvantages such as a decrease in analytical ability. SUMMARY OF THE INVENTION An object of the present invention is to provide a positioning device for a rotary motion mechanism that detects the absolute position of a drive mechanism and has good positioning reproducibility.

[Structure of the Invention] (Means for Solving the Problems) The structure of the present invention for solving the above problems includes, in a rotationally driven drive mechanism, a light source provided at a predetermined position of the drive mechanism; A configuration including a concave diffraction grating that diffracts the received light according to an angle corresponding to the stop position of the light source, and a plurality of light receiving elements arranged on the Rowland circle of the concave diffraction grating and receiving the diffracted light. did.

(Function) The function of the present invention having the above configuration is that the concave diffraction grating has a diffraction angle determined by -i depending on the incident angle of light emitted from a light source provided at a predetermined position on a rotationally driven drive mechanism. Therefore, the diffraction angle of the light from the concave diffraction grating changes as the position of the light source changes, so by detecting this reflected light with a photodetector arranged on a Rowland circle, the absolute position of the light source can be determined. It will be done.

(Example) The present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of an automatic chemical analysis apparatus to which a positioning device in a rotational movement mechanism of the present invention is applied.

In the figure, 1 is a concave diffraction grating which will be described later, 2 is a light source that irradiates the concave diffraction grating in order to determine the rotational position of the drive mechanism, and 3 is a light receiving unit that receives light diffracted from the concave diffraction grating. element, 4 is a reaction tube storage ring in which a plurality of reaction tubes 4a are arranged and rotated in a fixed direction; 5 is a detector that detects light from a light receiving element and calculates the position of the thick light receiving element; 6 is a CPU that controls this device
, 7 is a pulse motor that drives the reaction tube storage ring 4.

The Moeki concave diffraction grating 1 is a diffraction grating in which metal is deposited on the surface of a concave member and scored lines are formed on this surface. This concave diffraction grating 1 becomes a group of equally spaced straight lines when projected lines are projected onto a tangential plane touching at the apex of the spherical surface.

A circle whose diameter is the radius of curvature of a spherical surface and touches the center of the spherical surface is called a Rowland circle. When a slit is provided on the Rowland circle and light is incident, the spectrum is imaged along the Rowland circle. Therefore, by arranging a plurality of light receiving elements along the Roland circumference, light will always form an image on these light receiving elements. Further, when such a concave diffraction grating is used, there is an advantage that no auxiliary optical element is required and there are few aberrations.

Next, concave diffraction grating 1. Light source 2. The relationship with the light receiving element 3 will be explained.

Here, the angle between the normal direction of the concave diffraction grating 1 and the light irradiated from the light source is β, and the angle between the light diffracted from the concave diffraction grating 1 and the normal direction is α.

Assuming that the number of ruled lines is N1, the diffraction order is m, and the long sword wavelength is λ,
Between these, sin a + sin β= N-m-λ
- The relational expression (1) holds true. That is, when the absolute position of the light source 2 provided on the drive mechanism 4 changes, the angle between the light diffracted from the concave diffraction grating 1 and the normal line is α, which uniquely changes with the change in the light source. By calculating the position of the light receiving element that received the diffracted light, the absolute position of the light source 2 can be known.

The light receiving element 3 is arranged on the Rowland circle and receives light emitted from the light source 2 provided at a predetermined position of the drive mechanism 4 and diffracted by the concave diffraction grating 1. Moreover, these plurality of light receiving elements 3 receive light that is rotationally driven! They are arranged to the extent that the accuracy required to detect the position of No. 2 can be obtained. The position of the light-receiving element that has received the light from the concave diffraction grating 1 is detected by the detector 5 connected at the subsequent stage. In other words, the light receiving elements are arranged at fixed angles on the Rowland circle. Therefore, the absolute position of the light source can be calculated by the CPU 6 based on the position of the light receiving element that receives the light. By calculating the absolute position in this way and controlling the rotation by the pulse motor 7 based on the calculation result, it is possible to improve the reproducibility of positioning when stopped, and also to use a concave diffraction grating. This allows for high resolution.

On the other hand, this positioning device may also be used as an aid. Specifically, in order to perform a certain degree of positioning using other positioning means, and then perform accurate positioning using the positioning device of the present invention, the signal from the light receiving element is fed back, and the pulse motor is controlled based on this amount of feedback. Even if the rotation of the drive mechanism is controlled, the stop position of the drive mechanism can be repeatedly and accurately reproduced.

FIG. 2 shows a modification of the embodiment shown in FIG. 1 above.

The difference between the positioning device shown in the figure and the positioning device shown in FIG. 1 is that the concave diffraction grating shown in FIG. The point is that it is attached with the Even when the concave diffraction grating 1 is mounted on the drive mechanism in this way, the concave diffraction grating 1. Light source 2. Since the relationship with the light receiving element is constant, the absolute position of the light source can be calculated.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a positioning device for a rotary motion mechanism that detects the absolute position of the drive mechanism and has good positioning reproducibility.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of an automatic chemical analysis apparatus to which the positioning device in the rotational movement mechanism of the present invention is applied. DESCRIPTION OF SYMBOLS 1... Concave diffraction grating, 2... Light source, 3... Light receiving element, 4... Drive mechanism.

Claims (3)

[Claims] (1) In a rotationally driven drive mechanism, a light source provided at a predetermined position of the drive mechanism, a concave diffraction grating that diffracts received light according to an angle corresponding to the stop position of the light source, and a concave diffraction grating that 1. A positioning device for a rotational movement mechanism, comprising a plurality of light receiving elements arranged on a Rowland circle and receiving diffracted light. (2) A positioning device in a rotational movement mechanism according to claim 1, wherein the concave diffraction grating is fixed at a predetermined position. (3) A positioning device in a rotational movement mechanism according to claim 1, wherein the concave diffraction grating is provided on a drive mechanism.