JPH0545213A - Method and apparatus for detecting error in light quantity measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] To detect the cause of an error due to the life of the light source in advance, to facilitate the maintenance of the light quantity measuring device, and to improve the reliability of the measurement data. When starting, the subroutine A is first executed for white plate correction, the correction coefficient is obtained, and then the sample is measured.
Process the data and output the result. In subroutine A,
Corrective measurement is performed M times on the white board, and if the maximum and minimum values are within the allowable range, processing is performed to obtain a correction coefficient, and the process returns. If no, a correction measurement error is displayed and the process goes to the end. The present invention jumps to the subroutine B before the correction processing, calculates the dispersion value showing the variation of the light emission amount of the light source, and returns if it is within the allowable range, but if it is not, displays a light source error and returns to the end. go.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error detecting method and apparatus for a light quantity measuring apparatus, in which the quantity of light emitted from a light source is reflected or scattered by a sample or transmitted through a sample is received by a photoelectric conversion element to measure the error quantity. The present invention relates to a method and an apparatus for detecting an error due to the life of a light source or the like.

[0002]

2. Description of the Related Art A light quantity measuring device for irradiating a sample with a light source and measuring the quantity of light reflected or scattered by the sample or transmitted through the sample by a photoelectric conversion element (hereinafter also referred to as "sensor") is used. Reflectance meter mainly by reflection, densitometer, transmittance meter mainly by transmission, densitometer,
Widely applied to turbidity meter, gloss meter by reflection and scattering, suspended matter detection device in gas or liquid mainly by scattering, and spectroscopic reflectance meter, spectroscopic transmittance meter, colorimeter, etc. which have a problem of spectral characteristics Has been done.

In a relatively simple device, an incandescent lamp is used as a light source, and a sensor such as a non-accumulation type Se photovoltaic cell utilizing a photoelectromotive force or photoconductivity, a Si diode, a CdS photoconductor is used. In addition, by using a flash light source with a much larger instantaneous light intensity and a storage type sensor than other light sources, and shortening the measurement cycle, the effect of stray light due to dark current and external light is reduced, Some have improved operability.

However, regardless of whether an incandescent lamp or a flash light source is used, the amount of emitted light varies a little from measurement to measurement due to slight fluctuations in the power supply voltage, so that modulation such as reflection, scattering, or transmission by the sample occurs. In addition to the sensor that receives the received measurement light amount, a sensor that directly monitors the light source is provided, and the influence of the variation in the light emission amount is excluded by dividing the measurement data by the monitor data, that is, normalizing.

Further, in the case where the sensitivity (photoelectric conversion rate) of the sensor or the spectral characteristic such as a colorimeter is a problem, the influence of the temporal change in the spectral characteristic of the light source and the sensor is excluded, so that the white plate correction is performed before the sample measurement That is, a standard white plate is used for reflection, and a colorless transparent substance (hereinafter collectively referred to as “white plate”) is measured for transmission, and the measured data at 100% (value if calibration data is known) is obtained. The data was stored and corrected when the sample was measured.

Further, there has been a method in which the white plate is measured a plurality of times and the average value of the measured data is stored to perform the white plate correction. Alternatively, in a plurality of white board measurements, by determining whether the maximum value and the minimum value of the monitor data corresponding to the light emission amount of the light source or the measurement data before normalization are within preset ranges, respectively. In some cases, it was checked whether the light source was inferior or the white board was measured correctly, and if there was an error, it was displayed.

[0007]

However, if the allowable range of the maximum value and the minimum value, which are the criteria for the above judgment, is set to be too narrow, an error is displayed even if the data can be sufficiently covered by the normalization by the bending angle monitor data and the white plate correction. There is a problem of frequent occurrence. On the contrary, if the allowable range is set to be wide, there is a problem in that it is not possible to detect an aging change of the light source or its power source, that is, an error due to the life.

The present invention has been made in view of the above points, and it is possible to detect the cause of an error due to the life of the light source in advance, facilitate the maintenance of the light quantity measuring device, and improve the reliability of the measurement data. The purpose is to

[0009]

In order to achieve the above-mentioned object, the first invention is to irradiate a sample with a light source and photoelectrically convert the amount of light reflected or scattered by the sample or transmitted through the sample. In the error detection method of the light amount measuring device which receives and measures by the conversion element, the correction measurement for the white plate correction is performed a plurality of times prior to the sample measurement, and the plurality of data corresponding to the light emission amount of the light source obtained thereby is obtained. It is determined whether the dispersion value is within a preset range, and if it is within the range, the measurement routine is continued, and if it is not within the range, a light source error is output.

A second aspect of the present invention comprises a light source for irradiating a sample and a photoelectric conversion element, and a light amount measurement for measuring the light amount of the irradiation light of the light source reflected or scattered by the sample or transmitted through the sample by the photoelectric conversion element. In the error detection device of the device, it corresponds to the correction measurement control means for controlling the correction measurement for the white plate correction prior to the sample measurement so as to perform the preset multiple times, and the light emission amount of the light source obtained by the multiple correction measurements. Computation means for calculating a required variance value from a plurality of data, determination means for determining whether or not the variance value calculated by the computation means is within a preset range, and the determination means for no At the same time, an error output means for emitting a light source error alarm or displaying or printing a message is provided.

[0011]

In general, a light source that has reached the end of its life tends to gradually decrease its light emission amount. However, the light source tends to become unstable and the light emission amount tends to vary more remarkably.

Therefore, according to the error detecting method of the light quantity measuring device according to the first aspect of the present invention, it is determined whether the dispersion value of the data corresponding to the light emission quantity of the light source of the correction measurement performed a plurality of times is within the preset range. It is determined whether or not it is within the range, and a light source error is output. Therefore, highly accurate error detection is performed.

In the error detecting device of the light quantity measuring device according to the second aspect of the invention, the correction measurement control means controls the correction measurement a plurality of times, and the calculating means obtains a plurality of data corresponding to the light emission amount of the light source. Calculate the variance. The determination means determines whether or not the variance value is within a preset range,
If the result is negative, the error output means issues a light source error alarm or displays or prints a message, so the operator can easily know that the light source is approaching the end of life and take measures such as light source replacement. Can be done.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing an example of an optical system of the spectral transmittance meter which is an embodiment of the present invention.

The flash light source 1 composed of a cold cathode xenon discharge tube, for example, is connected to a capacitor charged to a relatively high voltage (not shown) and a trigger circuit. When a high voltage trigger signal is applied from the trigger circuit, the flash light source 1 is applied to the capacitor. The charged electric charge is discharged and a strong flash light is emitted in a short time of about several tens to several hundreds of μs.

The emitted light is converted into parallel light by the collimator lens 2 and irradiates the sample 3, and the parallel transmitted light that has passed through the sample 3 is separated by the diffraction grating 4 and then is formed by the imaging lens 5 in the photodiode array. (Photoelectric conversion element group) Photodiode P which is a plurality of photoelectric conversion elements
A spectrum, that is, a spectral light amount distribution image is formed on the light receiving surface composed of 1, P2 ... Pn.

The spectral light amount distribution is converted into a current or an electric charge by each of the photodiodes P1 to Pn corresponding to each spectral region and measured by a measuring circuit (not shown) in the subsequent stage. Generally, the spectral sensitivity of the photodiode is not always uniform. However, since the materials constituting the photodiode, such as Se, Ge, Si, etc., show different characteristic spectral sensitivity characteristics, correct spectral transmittance characteristics cannot be obtained as they are.

Therefore, white plate correction is performed before measuring the sample. That is, a colorless and transparent material whose optical characteristics are close to those of the sample, that is, if the sample is, for example, a photographic filter, a gelatin film or optical glass, and if it is a liquid sample, a standard sample (white plate) such as its solvent or an equivalent liquid is measured. Correct spectral transmittance characteristics can be obtained by taking the ratio with the measured data.

On the other hand, in the photodiode array 6, another photodiode Pn + 1 is provided adjacent to the photodiode Pn for light source monitoring.
The open end 7a of the optical fiber 7 is in close contact with the photodiode Pn + 1, and the other open end 7b is passed through the ND (neutral density) filter 8 to the flash light source 1
Is facing.

Therefore, when the flash light source 1 emits light, a part of the emitted light is transmitted through the sample 3 and is dispersed into the photodiodes P1 to Pn, and at the same time, another part of the emitted light is emitted from the ND filter 8 and the optical. It is incident on the monitoring diode Pn + 1 through the fiber 7. The ND filter 8 is provided to balance the amount of light that is split into the photodiodes P1 to Pn by attenuating the monitor light.

FIG. 3 is a circuit diagram showing a structural example of an electric system of the embodiment (spectral transmittance meter) shown in FIG. The electrical system shown in FIG. 3 is roughly divided into a light source unit 10, a light receiving unit 11, and
The measuring unit 12 is a measuring unit, and the control unit 20.

The light source unit 10 supplies the flash light source 1 and light emission power to the flash light source 1, and also emits a light emission signal F.
The flash power supply 14 outputs a trigger signal according to S, and the flash power supply 1 receives the light emission signal FS.
A flash light source 1 emits a flash light of a predetermined light amount determined by the capacity of a power capacitor (not shown) in 4 and its charging voltage.

The light receiving section 11 is composed of a photodiode array 6
And the photodiodes P1 to Pn + 1 that compose it
And a battery 15 for applying a reverse bias DC voltage to the. The capacitors C1 to Cn + 1 shown in parallel with the photodiodes P1 to Pn + 1 are junction capacitances,
Although its capacity is very small, it accumulates electric charges generated in proportion to the amount of received light, and discharges the electric charges during measurement to be cleared.

The measuring section 12 as a measuring means is composed of a multiplexer (analog) 16, a charge amplifier 17 and an A / D converter 18. Multiplexer 1
6, the address is cleared according to the input of the measurement signal MC,
While counting up the address according to the clock CLK, the charge accumulated in the junction capacitance Ck of the photodiode Pk corresponding to the address k is taken out and output to the charge amplifier 17 in the next stage. When the address reaches its maximum value, it does not count up even if the clock CLK is input.

The charge amplifier (integrating amplifier) 17 is a sample and hold circuit which is basically composed of an operational amplifier OP and a parallel circuit of a capacitor C and a switch SW inserted in a feedback circuit of the operational amplifier OP. The charging voltage Vs of the capacitor C, which is proportional to the amount of electric charge serially output in synchronism with, is output to the A / D converter 18 in the next stage.

A switch S composed of, for example, a semiconductor switch
W is the A / D converter 18 in synchronization with the clock CLK.
Holds the voltage Vs for a time required for conversion, and then both ends of the capacitor C are momentarily short-circuited to discharge and prepare for the measurement of the amount of electric charge to be input next. The A / D converter 18 converts the analog output voltage Vs of the charge amplifier 17 into, for example, 8 to 16-bit digital measurement data and sends it to the next-stage microcomputer (hereinafter referred to as “MCP”) 21 without needing to explain it again. Output.

The control unit 20 is composed of an MCP 21 and a control logic circuit 22. MCP21 is CPU2
3, ROM 24, RAM 25, etc., and the CPU 23 controls the entire apparatus based on a program stored in advance in the ROM 24, and outputs a measurement start signal MST to the control logic circuit 22 in accordance with an operator's instruction.
Start the measurement.

Further, the CPU 23, which is an arithmetic means, temporarily stores the measurement data output by (the A / D converter 18 of) the measuring section 12 in the RAM 25, which is a data storage means, and then averages the plurality of data. The calculation of the statistic or the ratio (relative value) of the statistic to the average value is performed, and calculation such as dividing the measurement data by the monitor data and normalizing is executed, and the obtained data is stored in the RAM 25.
To store.

The control logic circuit 22 receives the clock CLK output from an internal oscillator (not shown) or input from the CPU 23 of the MCP 21, and switches SW and A of the multiplexer 16 and the charge amplifier 17 constituting the measuring section 12.
The clock C is output to the / D converter 18
The LK is counted to form the measurement signal MC and the light emission signal FS, and the multiplexer 16 and the flash power supply 14 are respectively provided.
And output to.

That is, when the measurement start signal MST is input, the control logic circuit 22 outputs the first measurement signal MC1 to the multiplexer 16, and the multiplexer 16 responds to the clock CLK and the junction capacitances C1 to Cn + 1 of the photodiodes P1 to Pn + 1. The charge accumulated in is taken out and cleared. On the other hand, the control logic circuit 22 counts the clock CLK after outputting the measurement signal MC1,
When (n + 1) is exceeded (when the photodiode has been cleared), the light emission signal FS is output to the flash power supply 14, and counting is continued to stop the emission of light from the flash light source 1 (several + to several hundred μs). Then the second measurement signal M
C2 is output to the multiplexer 16.

The flash light source 1 emits light in response to the light emission signal FS, and the light transmitted through the sample 3 and dispersed by the diffraction grating 4 is incident on the photodiodes P1 to Pn and is attenuated by the ND filter 8 to pass through the optical fiber 7. The monitor light thus passed enters the photodiode Pn + 1. The amount of charge accumulated by each of the incident lights is measured signal MC2.
1 that operates according to the clock and the clock CLK
While serially taken out by 6 and sample-held by the charge amplifier 17, each digital measurement data (1 to n) is taken by the A / D converter 18.
And monitor data (n + 1) and stored in the RAM 25 of the MCP 21.

FIG. 1 is a flow chart showing an example of a measurement routine program stored in advance in the ROM 24. The vertical flow from "start" to "end" on the left side shows the main routine of measurement, and the central flow The vertical flows following A and B on the right side show subroutines for whiteboard correction and variance verification, respectively, except for the error display routine when an error occurs.

When the main routine starts, the white plate correction (subroutine A) is executed after the white plate for white plate correction is set. Next, if necessary, the reference color measurement is executed after the reference color plate is set, as indicated by the broken line.

White plate correction, reference color measurement and sample measurement are
The operation of the operator and the routine for storing the measured data in the RAM 25 are exactly the same, and the processing of the stored data thereafter is different. Therefore, the operator (for example, by a changeover switch (not shown)) switches each mode of (1) white plate correction, (2) reference color measurement, and (3) sample measurement, and then enters each measurement operation. → (2)
→ (3) or (1) → (3) You can choose either course.

Also in the sample measurement, the measurement is performed (usually a plurality of times) after the sample is set, and the data processing is started. The n pieces of measurement data obtained by the photodiodes P1 to Pn are simultaneously detected by the photodiode Pn + 1.
After eliminating the influence of the variation of the light emission amount of the flash light source 1 by normalizing each with the monitor data obtained by, the correction data obtained by the white plate correction corresponding to each photodiode, that is, each spectral region, is performed. However, correct spectral distribution characteristic data excluding the influence of each variation factor can be obtained.

If the light quantity measuring device is a colorimeter, a process of calculating chromaticity coordinates x, y or u, v of the CIE XYZ color system or the UCS color system from the spectral distribution characteristic data is added. Finally, the result of the obtained spectral distribution characteristic data or the chromaticity coordinates is displayed or printed as a table or a graph to finish.

When jumping to the subroutine A in the white plate correction, first, a preset M times of correction measurement is executed, and each measurement data and monitor data are stored in the RAM 25 for each time. Next, for example, the maximum value and the minimum value of the sum (M pieces) of the measurement data for each time are detected, and compared with the allowable maximum value and the allowable minimum value that are preset for the white board, and both are within the range. It is determined whether or not

The allowable maximum and minimum values are set wide enough to correct the variation in the light emission amount of the flash light source 1 by normalizing each measurement data with the monitor data. Although it is not judged as an error, if the white board is not set correctly,
If you have accidentally set a different correction plate, or if external light is mixed in, it will be judged as an error by exceeding the allowable limit, and an error output means (not shown) such as an electronic buzzer, display or printer will A correction measurement error alarm will be output, a message will be displayed or printed out, and you will go to the end.

Therefore, in the above determination, it is difficult to determine the life of the light source unless the light amount is significantly reduced. Therefore, in the present invention, the variance test as described below is performed on the data in which the maximum value and the minimum value are within the allowable range.

When jumping from the variance test to the subroutine B, M pieces of monitor data corresponding to the light emission amount of the flash light source 1 among the data obtained by the measurement (for example, the measurement data or the sum of the measurement data is a white plate). (May be used instead), and a variance value such as a range R (= maximum value-minimum value) or σ (standard deviation) indicating the average value and the variation is calculated.

Generally, the range R is suitable when M is small, and σ is suitable when M is large. Also, the range R or σ
By taking the relative dispersion value by dividing by, the variation due to instability can be excluded and the variation due to instability can be more accurately captured.

Next, the range R or σ selected as the variance value
Alternatively, it is determined whether or not any one of the relative values is within the range set corresponding to the preselected variance value, and if it is within the range, the process returns to the subroutine A variance test, and the result is NO. If there is, a light source error alarm or message is output and the process goes to the end. Therefore, the operator may investigate the cause of the light source error (first is the life of the flash light source) and take a corrective action.

If there is no error in the correction measurement or the light source, and the procedure returns to the dispersion test, the process proceeds to the next correction process, and each measurement data is divided by the monitor data obtained at the same time to normalize it, and then M for each photodiode. Find the reciprocal of the average of the normalized data. In the case of white plate correction, a correction coefficient can be obtained by multiplying the inverse number by 100.

These correction coefficients are for obtaining corrected correct spectral light quantity characteristics by multiplying the corresponding normalized measurement data at the time of sample measurement. When the correction coefficient for each of the N photodiodes corresponding to each spectral region is obtained, the correction process ends and the subroutine A returns to the white plate correction of the main routine.

As described above, according to the present invention,
Since the life of the light source is determined by verifying the variation of the light emission amount due to the instability of the light source, it is possible to perform the determination with higher accuracy than that of the conventional method of decreasing the light emission amount.

Further, as shown in the embodiment, it goes without saying that the accuracy of the determination can be further improved by using it together with the conventional determination based on the decrease in the light emission amount.

[0047]

As described above, according to the present invention,
It is possible to detect the cause of an error due to the life of the light source in advance, facilitate the maintenance of the light quantity measuring device, and improve the reliability of the measurement data.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a program of a measurement routine in an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of an optical system of a spectral transmittance meter that is an embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration of an electric system of the embodiment shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Flash light source (light source) 3 Sample 6 Photodiode array 10 Light source part 11 Light receiving part 12 Measuring part 20 Control part 23 CPU (correction measurement control means, calculation means, determination means) P1, P2 ... Pn, Pn + 1 Photodiode (photoelectric conversion element)

Claims (2)

[Claims] 1. A method for detecting an error in a light quantity measuring device, which comprises irradiating a sample with a light source, and measuring the quantity of light reflected or scattered by the sample or transmitted through the sample by a photoelectric conversion element. Is performed a plurality of times of correction measurement for white plate correction prior to, it is determined whether the dispersion value of the plurality of data corresponding to the light emission amount of the light source obtained thereby is within a preset range, If it is within the range, the measurement routine is continued, and if it is not within the range, a light source error is output. 2. A light quantity measurement device comprising a light source for irradiating a sample and a photoelectric conversion element, wherein the light quantity of the irradiation light of the light source reflected or scattered by the sample or transmitted through the sample is received and measured by the photoelectric conversion element. In the error detection device of the device, correction measurement control means for controlling correction measurement for white plate correction prior to sample measurement to be performed a plurality of times set in advance, and the light emission amount of the light source obtained by the plurality of correction measurements. Calculating means for calculating a required variance value from a plurality of data corresponding to, determining means for determining whether the variance value calculated by the calculating means is within a preset range, and the determining means Error detection means for emitting a light source error alarm or displaying or printing a message when the determination is made. Location.