JP2002310790A - Chopping device and optical measuring instrument using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a chopping device to perform chopping at a high speed. SOLUTION: The chopping device 20 is provided with two discoid chopper plates 20a and 20b which are arranged coaxially with respect to their center axes. In the plates 20a and 20b, light transmitting openings 21a and 21b are respectively arranged at regular intervals along their circumferences. The second chopper plate 20b is fixed and the first chopper plate 21a is rotated. A measuring luminous flux 23 passes through the lapping sections of the openings of the chopper plates 20a and 20b and data are processed synchronously to the period of rotation of the first chopper plate 20a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a sample with a measurement light beam in a desired wavelength range from ultraviolet / visible to infrared.
By detecting reflected light, transmitted light, fluorescence, etc. from the sample due to the interaction between the measurement light and the sample, an optical measurement device that measures the physical properties and concentration of the sample, and such an optical measurement device, The present invention relates to a chopping device used to improve the signal-to-noise ratio (S / N).

[0002]

2. Description of the Related Art A chopping device is often provided on a measurement optical path in order to perform measurement with an S / N ratio increased by an optical measuring device. The chopping device intermittently intermits the luminous flux at a constant cycle by rotating a notched circular plate or an arc-shaped chopper plate, or by reciprocating a notched chopper plate in a linear direction. Processing the detection signal, the S / N caused by disturbance light
The ratio is prevented from dropping.

A light source used in an optical measuring device has an area of several mm in diameter even if it is optically converged, unlike an ideal point light source. If a pinhole mask is provided, it is possible to reduce the cross-sectional area of the light beam, but this is not an effective measure because the amount of light is reduced. For this reason, in order to mechanically generate light and darkness with a chopper using one disk or chopper plate, it is necessary that the opening and closing of the chopper have a size larger than the light flux.

As a mechanism for driving a mechanical chopper, a motor is used in a rotating system, and a voice coil or a piezo element is used in a linear moving system. The motor has a limit in high-speed rotation, and the one used in the optical device is generally about 10000 rpm in a no-load state. Usually, it is often used at a further reduced speed. Although voice coils and piezo elements can be driven at higher speeds than motors, it is difficult to drive a large chopper mechanism because it is basically a drive mechanism that moves linearly and many have a small driving force. It is.

It is possible to perform high-speed chopping by increasing the number of cutouts in the chopper. You have to make it bigger. This makes it difficult to perform high-speed chopping, which is an obstacle to increasing the measurement speed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a chopping device which enables high-speed chopping and an optical measuring device using the same.

[0007]

The chopping apparatus of the present invention includes first and second two chopper plates and a movement drive mechanism for driving the movement of the first chopper plate. The two chopper plates are adjacently arranged in parallel with each other, the light transmission openings are arranged in a line at equal intervals in the first chopper plate, and the first chopper plate is arranged in the second chopper plate. At least one opening is formed at a position overlapping the opening of the plate, the second chopper plate is fixed,
The first chopper plate is moved by the moving drive mechanism so that the overlapping portion of the openings of both chopper plates opens and closes.

[0008] In one aspect of the present invention, both of the two chopper plates may be disc-shaped. In that case, 2
The chopper plates are arranged with the central axis coaxial,
The openings of the first chopper plate are arranged along the circumference, and the first chopper plate is adapted to be rotated by the moving drive mechanism with its center axis as a rotation axis. it can.

In another aspect of the present invention, the openings of the first chopper plate are arranged in a straight line, and the first chopper plate is moved by the moving drive mechanism so as to reciprocate along the linear direction. It can be adapted to be moved.

In order to ensure that the light beam is interrupted by the intermittent light beam by the chopping device, an opening formed in one of the chopper plates should be formed as follows.
It is set smaller than the closed portion between the openings formed in the other chopper plate.

An optical measuring apparatus according to the present invention comprises a light source optical system for irradiating a sample with a measurement light beam and a light receiving optical system for receiving and detecting light from the sample. The above-described chopping device of the present invention is provided on the optical path of the measurement light beam reaching the optical system.

In order to improve the S / N ratio, the frequency determined by the number of openings provided in the first chopper plate and the driving cycle of the first chopper plate is centered.
It is preferable to include a data processing device for performing a filtering process on the detection signal by the light receiving optical system.

Further, in order to eliminate the influence of variations in the openings provided in the first chopper plate, the data processing device has a function of integrating detection data over an integral multiple of the driving cycle of the first chopper plate. It is preferable to have.

[0014]

FIG. 1 schematically shows an optical measuring apparatus according to an embodiment, in which a first embodiment of a chopping apparatus is also shown. Chopping device 20
Has two chopper plates 20a and 20b. Each of these choppers 20a and 20b has a disk shape and is arranged coaxially with the center axis. In the first chopper plate 20a, light transmission openings 21a are arranged at equal intervals along the circumference of the chopper plate 20a. Openings 21b are also arranged on the second chopper plate 20b at equal intervals along the circumference of the chopper plate 20b, corresponding to the openings 21a of the first chopper plate 20a. I have. The chopper plate 20b is fixed to the optical measuring device, and the chopper plate 20a is rotated at a constant speed by a motor 18 as a moving drive mechanism with its center axis as a rotation axis. In order to detect the rotation of the chopper plate 20a,
The photo interrupter 24 is located around the chopper plate 20a.
Is provided. As shown later in FIG. 2, a hole 25 detected by the photo interrupter 24 is formed in the chopper plate 20a on the outer periphery of the chopper plate 20a.

The measurement light beam 23 is supplied to the chopper plates 20a and 20b.
Through the overlapping portions of the openings. Chopper plate 20
The transmission of the light beam is interrupted by the rotation of a. A detector 22 is disposed to detect the measurement light beam 23 passing through the chopper mechanism 20. A detection signal of the detector 22 is converted into a digital signal by an A / D conversion circuit 30 through amplification circuits 26 and 28. , And a microcomputer unit 32 that performs signal processing.

The detection signal of the photo interrupter 24 is taken into an amplifier circuit 28, and the amplifier circuit 28 converts only the frequency synchronized with the frequency of the signal of the photo interrupter 24 into an A / D signal.
It is sent to the conversion circuit 30. The amplifying circuit 28 is a filter circuit, and increases the S / N ratio of the signal by synchronizing and modulating the signal with the detection signal of the photo interrupter 24. The part that amplifies the signal of the detector 22 and processes it as a digital signal is a data processing device. In this example, the amplifier circuit 26,
28, A / D conversion circuit 30, microcomputer unit 3
Contains 2.

The optical measuring devices to which the present invention is applied are various optical measuring devices for measuring the interaction of the sample with the measuring light, such as the absorbance, reflectance, fluorescence, etc. in any of the ultraviolet, visible, and infrared regions. Contains. Although not shown in the drawing, a spectral filter, a diffraction grating, and other spectral elements can be arranged on the optical path as needed. Light sources and detectors can be used by selecting appropriate ones according to the respective wavelength ranges.

One example of the application of the optical measuring device of the present invention in the measurement in the infrared or near-infrared region is the use of plastics such as plastic bottles or sheet-like plastic waste to recycle plastic materials. A material discriminating apparatus that separates and collects materials can be used. In the material discriminating device, the plastic material is irradiated with light in the near infrared region,
Light reflected or transmitted from a plastic material is received, and the material is determined from its spectral characteristics. At that time, by using the chopping device of the present invention, material discrimination can be performed at high speed.

FIG. 2 illustrates the rotating chopper plate 20a in this embodiment. Chopper plate 20
Openings 21a are arranged at equal intervals along the circumference of a. A hole 25 for detecting a reference position of the chopper plate 20a by the photo interrupter 24 is formed outside the arrangement of the openings 21a. Chopper plate 20a
A hole 40 for passing the rotation shaft of the motor 18 and a hole 42 for fixing the chopper plate 20a to the rotation shaft are formed in the center of the hole.

The other chopper plate 20b is a chopper plate 20
An opening 21b is provided at the same size, the same size, and the same interval at the corresponding position. Chopper plate 2
The reference numeral 0b is fixed to the optical measuring device, and does not rotate, so that the hole 25 for detecting the reference position is not provided.
A hole is formed in the center of the chopper plate 20b for passing the rotation shaft.

The specific dimensions of the chopper plates 20a and 20b are approximately 130 mm, and the openings 21a and
1b is formed so as to have an arc angle of 2 °, and the closed portion between the openings is set to have a larger arc angle of 3 °. Two chopper plates 20a,
By setting the closing portion of the opening 20b to be larger than the opening as described above, the light beam can be reliably blocked on the optical path of the measurement light beam.

In the fixed chopper plate 20b, at least one opening is required in a portion through which the measurement light beam passes, but no opening may be provided in a portion through which the measurement light beam does not pass.

FIG. 3 schematically shows a second embodiment of the chopper device. Two chopper plates 40a and 40
b is a rectangle, and openings 42a and 42b are arranged at regular intervals on a straight line. The chopper plates 40a and 40b are arranged parallel to each other, and have openings 42a and 42b.
Correspond to the positions. The chopper plate 40a is driven by a voice coil motor, a piezo element, or the like in a reciprocating direction on a straight line along the arrangement of the openings 42a as indicated by arrows. The openings 42a and 42b are also set so that the size of the closed part is larger than that of the opening as in the embodiment of FIG.

FIG. 4 shows a detection signal in the embodiment of FIG. In the range shown as chopper 1 rotation data in the lower side of FIG. 2A, the reference position of the chopper plate 20a is detected by the photo interrupter 24 through the hole 25,
This represents a detection signal for one rotation until the next detection. In the one rotation data, a number of signals corresponding to the number of the openings 21a are detected. (B) is an enlarged view of the time axis for one part of the signal, and the position indicated by a black circle on the time axis indicates the A / D conversion timing.

In the data processing apparatus, data of an integral multiple of the region indicated as chopper one rotation data is integrated or further averaged, so that variations in the openings due to the position of the chopper plate can be averaged. it can.

[0026]

According to the chopping device of the present invention, two chopper plates are arranged adjacent to each other and parallel to each other, and light transmitting openings are arranged in a line at equal intervals in the first chopper plate.
At least one opening is formed in the chopper plate at a position overlapping with the opening of the first chopper plate, the second chopper plate is fixed, and the first chopper plate is overlapped with the openings of both chopper plates. Since the moving drive mechanism is used to open and close the portion, high-speed chopping becomes possible. Since the optical measuring device of the present invention includes the chopping device of the present invention on the optical path of the measuring light beam from the light source optical system to the light receiving optical system, it is possible to perform high-speed measurement when performing various measurements. Operation efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram schematically showing a chopping device and an optical measurement device according to one embodiment.

FIG. 2 is a front view showing a rotating chopper plate in the embodiment.

FIG. 3 is a schematic perspective view showing another embodiment of the chopper device.

4A and 4B are waveform diagrams showing detection signals in the embodiment of FIG. 1, wherein FIG. 4A shows a signal in a wide time range,
(B) is an enlarged view of the time axis for one part of the signal.

[Explanation of symbols]

 Reference Signs List 18 motor 20 chopping device 20a, 20b, 40a, 40b 21a, 21b, 42a, 42b light transmission opening 22 detector 23 measurement light beam 24 photo interrupter 26, 28 amplification circuit 30 A / D conversion circuit 32 microcomputer section

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noboru 14-5 Shimogitacho, Neyagawa-shi, Osaka Kurashiki Textile Co., Ltd. (72) Hiroshi Yokota 14-5 Shimogitacho, Neyagawa-shi, Osaka No. F-term in Kurashiki Textile Co., Ltd. Technical Research Laboratory (reference) 2G059 AA05 BB08 EE01 EE02 EE07 EE12 HH01 HH02 HH03 JJ02 JJ05 JJ24 KK01 LL04 MM01 NN01 2G065 AB02 AB04 AB05 AB22 AB23 AB30 BA01 BB26 BC28 BC02 BC28 BC02 AA04 AB05 AC01 AC04 AZ01 AZ05

Claims (7)

[Claims] A first chopper plate and a movement drive mechanism for driving the movement of the first chopper plate, wherein the two chopper plates are adjacently arranged in parallel with each other; The first chopper plate has light transmission openings arranged in a line at equal intervals, and the second chopper plate has at least one opening formed at a position overlapping with the opening of the first chopper plate. A chopping device in which a second chopper plate is fixed, and the first chopper plate is moved by the moving drive mechanism so as to open and close an overlapping portion of the openings of both chopper plates. 2. The two chopper plates are both disk-shaped, are arranged coaxially with a central axis, and the openings of the first chopper plate are arranged along the circumference. 1
The chopping device according to claim 1, wherein the chopper plate is rotated by the movement driving mechanism about a center axis thereof as a rotation axis. 3. The opening of the first chopper plate is arranged in a straight line, and the first chopper plate is moved by the moving drive mechanism so as to reciprocate along the linear direction. 6. The chopping device according to 1. 4. An opening formed in one of the chopper plates of the two chopper plates is set to be smaller than a closing portion between openings formed in the other chopper plate. The chopping device according to any one of the above. 5. An optical measuring apparatus comprising: a light source optical system for irradiating a sample with a measurement light beam; and a light receiving optical system for receiving and detecting light from the sample, wherein the light source optical system is connected to the light receiving optical system. An optical measuring device comprising the chopping device according to claim 1 on an optical path of a measuring light beam. 6. Data for performing a filtering process of a detection signal by the light receiving optical system around a frequency determined by the number of openings provided in the first chopper plate and a driving cycle of the first chopper plate. The optical measuring device according to claim 5, further comprising a processing device. 7. The optical measurement device according to claim 6, wherein the data processing device has a function of integrating detection data over a time period that is an integral multiple of a driving cycle of the first chopper plate.