JP2008157841A - Reliability improving method of photodetection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for measuring light intensity of transmitted light and reflected light, even if disturbance light enters by suppressing an influence. <P>SOLUTION: The on/off state of light irradiated at a light intensity measuring time is switched periodically, and an output from a photodetector is taken repeatedly synchronously with a period of irradiation/non-irradiation, and an integrated value of output values at the non-irradiation time is subtracted from an integrated value of the output at the irradiation time, to thereby eliminate an influence of the output value caused by disturbance light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photodetection device that irradiates an object to be measured with ultraviolet, infrared, or visible light, measures light intensity such as transmitted light, reflected light, and fluorescence generated at that time, and identifies components contained in the object to be measured.

  When a measurement is performed on an object, the measurement value always includes variation. In order to reduce the influence of this variation, it is said that measurement by the same operation is performed many times, and an average value in the result is calculated as a measured value.

  FIG. 1 is a block diagram showing a system capable of improving the accuracy of a detection value by repeatedly performing light detection. Reference numeral 1 denotes an object to be measured. Reference numeral 100 denotes a spectroscopic measuring instrument that can measure absorbance, and includes a light emitting unit 101 and a light receiving unit 102. The timing controller 3 controls the same object to be measured repeatedly a predetermined number of times. Each measurement result (absorbance value) is integrated by the integrator 2, an average value is calculated, and is output to the monitor 4 or other output device as measurement data in the form of a numerical value or a graph. Reference numeral 5 denotes a device having a function of reading a noise level, that is, a noise level detector, which reads a noise level from an output (averaged measurement data) of the integrator 2 and outputs a noise level value N. . The comparator 6 compares the noise level value N of the measurement data with a noise level reference value Rn set in advance as a parameter. If N is smaller than Rn, the comparator 6 transmits an output signal Rc to the timing controller 3. . Upon receiving this signal Rc, the timing controller 3 controls the spectroscope 1 to stop repeated measurements and also stops the integration in the integrator 2. The above procedure can be thought of as program processing on a computer equipped with software. Sequential processing is performed as in the flowchart of FIG. The storage device 8 executes setting of the reference value Rn and storage of the noise level value N.

JP 2001-330469 A

  In the above method, the integrator functions effectively for single noise generated during measurement, and it is possible to detect with high reliability by repeatedly measuring. However, when measuring light other than irradiation light, for example, ambient light such as room lights, the detection value is almost uniformly positive, so it is not possible to handle it. Will be. In such a case, the measurement part is usually dealt with by making it a dark room state in which ambient light does not enter. However, it may be difficult to completely put the light detection unit in a dark room due to problems such as operability in the light detection unit incorporated in the multifunctional clinical examination apparatus. In some cases, I was affected by the influences.

  In the invention of claim 1, in order to solve the above-mentioned problem, in a light detection device for measuring the light intensity of transmitted light, reflected light, fluorescence, etc. obtained from the object to be measured, and identifying the substance contained in the object to be measured , Means for periodically switching between irradiation and non-irradiation, means for repeatedly capturing the output of the photodetector in synchronization with the period of irradiation and non-irradiation, and subtracting the output value during non-irradiation from the output value during irradiation Since it has means, it becomes possible to eliminate an increase in output value due to disturbance light.

  According to the second aspect of the present invention, the detection of the output of the photodetector is continuously executed at a fixed period until immediately before the start of irradiation, the repetition at the time of irradiation, and the repetition immediately after the end of irradiation, and the repetition at the time of irradiation. In order to calculate the measured value from the value obtained by subtracting the average from the average of acquisition until just before the start of irradiation and the total average of repeat acquisition immediately after the end of irradiation, in addition to eliminating the increase in output value due to ambient light, the noise generated instantaneously The influence can also be reduced.

  Even when disturbance light enters and an offset occurs in the detected value, timely correction can be made and the influence of disturbance light can be eliminated.

  When a change occurs in the light receiving characteristics of the photodetector over time, the offset adjustment is always performed, so that accurate light detection is possible.

(Overall configuration of the embodiment)
Embodiments will be described below with reference to the drawings.

  FIG. 3 is a block diagram showing one embodiment of the present invention. In the spectroscope (1), the light irradiated from the light source (3) reaches the object to be measured, and at that time, the light generated from the object to be measured is selected (only a specific wavelength is transmitted), and transmitted light, reflected light, fluorescence, etc. Only the wavelength components that can be considered necessary are guided to the light receiving surface of the photoelectric converter (2). Subsequently, the detection light photoelectrically converted into an electrical signal is selected so as to be integrated into either the integrator A (7) or the integrator B (8) by the integrator switching (6). The noise levels obtained in the integrator A (6) and the integrator B (7) are compared with a predetermined noise level allowable value in the noise level detection (10). If the comparison result is outside the allowable range, the irradiation light ON / OFF (12) is controlled by the timing controller (11) at a preset period, and the light source (3) is transmitted via the irradiation light lighting driver (4). Functions to irradiate the object to be measured with light, and performs a light detection cycle in the same manner as described above. When the comparison result of the noise level detection (10) falls within the allowable value range, the light detection value correction processing unit (9 ), A correction calculation process is performed, and a result as a light detection value is output. Since the integrator switching (6) to the irradiation light ON / OFF (12) can be realized as software in a microcomputer, the microcomputer (100) is included.

FIG. 4 is a flowchart showing the sequence in the embodiment shown in FIG. In the microcomputer (100), the noise level allowable value R of the S1 light detection value is recorded in the noise level detection (10) by reading from the external storage device or by key input (not shown). It progresses to S2 measurement operation | movement and transfers to the optical detection (sampling) by a photoelectric converter (2). It is determined whether or not the S3 light detection data is in a state where irradiation light from the light source (3) is emitted. In the S4 irradiation state, integration of the light detection data is performed by the integrator A (7), and in the S5 non-irradiation state, integration of the light detection data is performed by the integrator B (8). As S6 noise level detection, the noise levels NA and NB of the integrator A (7) and the integrator B (8) are calculated. S7 Noise levels NA, NB and allowable value R are compared. If either NA or NB is greater than or equal to the allowable value R, the S8 irradiation light lighting time is increased (accumulators A and B are also added), and remeasurement is performed. The correction calculation is executed based on the integrated values SA and SB of the device B (8), the light detection value is calculated (output), and the process ends. As for the correction calculation process, light detection is executed a plurality of times at a fixed period in the non-irradiation state for a time ½ of the lighting time Ton before the irradiation light is turned on at the timing of FIG. At this time, integration of light detection data is performed by the integrator B (the integrated value at this time is set to ΣSoff1). Subsequently, after shifting to the irradiation light lighting state, light detection is performed a plurality of times at a constant cycle similar to that in the non-irradiation state, and integration is performed by the integrator A. (The integrated value at this time is set to ΣSon.) After the transition to the non-irradiation state again, the light detection is performed a plurality of times at a constant period for a half of the lighting time Ton as before the lighting. At B, the integration of the photodetection data (the integration value at this time is ΣSoff2, and ΣSoff = ΣSoff1 + ΣSoff2) is restarted. After the Toff time has elapsed, the light detection value S is calculated as S = ΣSon−ΣSoff. FIG. 6 is a graph showing the result of alternately performing the presence or absence of disturbance light incident during 10 repeated measurements of a plurality of specimens containing the same substance at different concentrations in relation to the concentration and the light detection value. . Error bars represent a range of ± 3σ (standard deviation). The left graph shows the photodetection value as the integrated value (ΣSon) only during irradiation, and the right graph shows the integrated value during irradiation−non-irradiated integrated value (ΣSon−ΣSoff).
(Other embodiments)
FIG. 7 is a block diagram showing another embodiment of the present invention. The spectroscope (101) is irradiated with light from the light source (103) and reaches the object to be measured. At that time, the light generated from the object to be measured is selected (only a specific wavelength is transmitted), and transmitted light, reflected light, fluorescence, etc. Only the wavelength components that can be considered necessary are guided to the light receiving surface of the photoelectric converter (102). Subsequently, the detection light photoelectrically converted into an electric signal is selected so that either addition or subtraction is performed in the adder / subtractor (107) by the addition / subtraction switching (106). The noise level obtained in the adder / subtractor (107) is compared with a predetermined noise level tolerance in the noise level detection (110). If the comparison result is out of the allowable range, the irradiation light ON / OFF (112) is controlled by the timing controller (111) at a preset period, and the light source (103) is transmitted via the irradiation light lighting driver (104). Functions to irradiate the object to be measured with light, and performs a light detection cycle in the same manner as described above. If the comparison result of the noise level detection (110) is within the allowable range, the light detection value correction processing unit (9) performs correction calculation processing based on the calculation data of the adder / subtracter (107). And output the result as a light detection value. In addition, since addition / subtraction switching (106) to irradiation light ON / OFF (112) can be realized as software in a microcomputer, these are included in the microcomputer (200).

  FIG. 8 is a flowchart showing a sequence in the other embodiment shown in FIG. In the microcomputer (200), the noise level allowable value R of the S11 light detection value is recorded in the noise level detection (110) by reading from the external storage device or by key input (not shown). Proceeding to S12 measurement operation, the process proceeds to photodetection (sampling) by the photoelectric converter (102). S13: It is determined whether the light detection data is in a state in which irradiation light from the light source (103) is emitted. In the S14 irradiation state, the addition / subtraction unit (107) adds the light detection data, and in the S15 non-irradiation state, the addition / subtraction unit (107) subtracts the light detection data. In S16 noise level detection, the noise level NC of the adder / subtracter (107) is calculated. S17 Comparison with noise level NC and allowable value R. If NC is greater than or equal to the allowable value R, the S18 irradiation light lighting time is added (plus the number of additions / subtractions of the adder / subtractor), and the measurement is re-measured. The calculation of the value is executed, and the calculation of the light detection value is finished (output).

It is a block diagram of the conventional photon detection apparatus. It is an operation | movement flowchart of the conventional photon detection apparatus. It is a block diagram of the photon detection apparatus of this invention. It is an operation | movement flowchart of the photon detection apparatus of this invention. It is light detection value calculation explanatory drawing of this invention. It is a graph which shows the precision at the time of measuring the measurement object CY5 by the conventional photodetector and the photodetector of this invention. It is a block diagram of the photon detection apparatus by the other form of this invention. It is an operation | movement flowchart of the photon detection apparatus by the other form of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spectrometer 2 Photoelectric converter 3 A / D converter 4 Light source 5 Illumination light lighting driver 6 Accumulator switching 7 Accumulator A (execution when light source is lit)
8 Accumulator B (Executed when the light source is turned off)
9 Light detection value correction calculation section
10 Noise level detection
11 Timing controller
12 Irradiation light ON / OFF controller
100 microcomputer

Claims (2)

  In a light detection device that measures the light intensity of transmitted light, reflected light, fluorescence, etc. obtained from a measurement object by irradiating the measurement object, and identifies the substance contained in the measurement object, Means to periodically switch the irradiation, means to repeatedly capture the output of the photodetector in synchronism with the irradiation / non-irradiation period, and means to subtract the non-irradiation output value from the irradiation output value Characteristic photo detector.   The light detection device according to claim 1, wherein the detection of the output of the light detector is continuously executed repeatedly at a fixed period until immediately before the start of irradiation, at the time of irradiation, and immediately after the end of irradiation. A photodetection method characterized in that a measurement value is calculated from a value obtained by subtracting a repeat average from repeated acquisition average immediately before the start of irradiation and a total average repeat acquisition immediately after the end of irradiation.

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