JPH0626932A - Colorimeter - Google Patents

Abstract

PURPOSE:To significantly minimize the peak value of a current to be supplied to a pulse light source such as an xenon lamp without causing a spectral shift in pulse light, increase the lamp life, and perform a precise measurement. CONSTITUTION:A current limit resistor R0 is provided between a main capacitor C0 for supplying a current to an xenon lamp 14 and the xenon lamp 14 to minimize the peak current, and the capacity of the main capacitor C0 is minimized to shorten the discharge time in the xenon lamp 14. On the light receiving side, a light receiving element array 24 is of energy accumulating type, and after the energy by emission for plural times is accumulated there, a signal is taken out to perform color calculation in a processing circuit 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colorimeter, and in particular,
The present invention relates to a colorimeter in which a lamp for irradiating a measurement sample has a long life and a spectrum of irradiation light is stable.

[0002]

2. Description of the Related Art Conventionally, as a spectrocolorimeter, a measurement sample is irradiated with pulsed light from a pulsed light source, and reflected light or transmitted light from the measurement sample is received by a light-receiving element array through a spectroscopic means. There is a device in which an output signal of an element is color-calculated by a processing circuit.

A xenon lamp is often used as the lamp of the pulse light source. A light emitting circuit of this xenon lamp is shown in FIG.
In the circuit of FIG. 4, when the contactless relay SR is turned on, the energy charged in the capacitor C ₁ is converted into high frequency and high voltage energy by the trigger coil T and applied to the electrode of the xenon lamp Xe.

As a result, the xenon gas of the xenon lamp Xe is dielectrically broken down, and a rapid discharge is generated between the electrodes of the lamp. Due to this discharge, the energy stored in the main capacitor C ₀ is also discharged by the xenon lamp Xe. The xenon lamp Xe will emit a strong light.

Here, the voltage applied to the main capacitor C ₀ does not start discharging at the xenon lamp Xe,
The trigger coil T is set to a voltage for discharging when dielectric breakdown occurs in the xenon lamp Xe.

[0006]

In a colorimeter, in general, the capacity of the main capacitor C ₀ in the light emitting circuit of the xenon lamp Xe is increased in order to increase the light energy received by the light receiving element array. .

Therefore, a large current flows through the xenon lamp Xe during light emission, and as shown by the symbol A in FIG. 5, for example, when the discharge time is 50 μS, the peak current becomes as large as 5000 A, which causes the electrode wear of the xenon lamp Xe. There is a problem that the lamp life is shortened.

Further, the fact that the peak current is large means that the peak of the sample irradiation light from the xenon lamp Xe is also large. Depending on the material of the sample, if the light intensity is above a certain level, a part of it will Will pass through,
In a colorimeter that measures reflected light from a sample, a problem arises in that accurate measurement cannot be performed.

In order to solve the above problems, an inductance L may be inserted in the light emitting circuit in FIG. By doing so, as indicated by the broken line B in FIG. 5, the problem that the peak current is greatly reduced and the lamp life is extended and part of the light passes through the sample can be solved.

However, when the peak current is lowered, the discharge energy is the same as that in the case of the solid line A, so that the discharge time becomes long as shown by the broken line B in FIG. 5, so that the spectrum shift occurs for each light emission. As a result, there arises a problem that accurate measurement cannot be performed.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a colorimeter capable of improving the life of a lamp without causing a spectrum shift. And

[0012]

The present invention irradiates a measurement sample with pulsed light from a pulsed light source, receives reflected light or transmitted light from the measurement sample through a spectroscopic means by a light-receiving element array, and In a colorimeter provided with a processing circuit for calculating a color by the output of a light receiving element, the light receiving element is an energy storage type element, and the processing circuit is configured to take out the energy stored in the light receiving element for each light receiving element. , The pulsed light source has a light emission time of 50 to 5 μS.
In addition, the energy accumulated in the light receiving element by one light emission is set to be 2 to several times the minimum energy required for color calculation in the processing circuit to achieve the above object. It is a thing.

[0013]

In the present invention, the peak value of the current supplied to the lamp in the pulse light source is made small and the discharge time is made short, the energy is accumulated a plurality of times in the energy storage type light receiving element, and the energy is extracted collectively. As a result, the color calculation is performed as in the conventional case, and it is possible to increase the lamp life, prevent the spectrum shift from occurring by reducing the peak current, and perform accurate measurement.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

A colorimeter 10 according to this embodiment comprises a light emitting circuit 12 and a xenon lamp 14, a pulse light source 18 for irradiating a measurement sample 16, a spectroscopic means 20 composed of a concave grating, and a spectroscopic means 20. An optical system 22 for guiding the reflected light from the measurement sample 16 and a spectroscopic means 2
The light receiving element array 24 receives the spectral light formed by 0, and the processing circuit 26 that processes the output signal of the light receiving element array 24 to calculate the color.

The measurement sample 16 is a xenon lamp 14
Is arranged so as to be detachable so as to face a diffusion chamber (integrating sphere) 28 for making the pulsed light from the sample into diffuse illumination.
It is designed to be taken out to the optical system 22 through A.
Reference numeral 28B in FIG. 1 denotes a baffle for preventing the light from the xenon lamp 14 from directly irradiating the measurement sample 16.

The optical system 22 has a window 28A of the diffusion chamber 28.
The reflected light extracted from the mirrors 22A, 22B, 22
It is led to the spectroscopic means 20 via C.

A beam expander 22D for increasing the diameter of the light beam is provided between the mirrors 22B and 22C. A slit 22E is provided between the mirror 22C and the spectroscopic means 20.

Each light receiving element in the light receiving element array 24 that receives the reflected light from the spectroscopic means 20 is an energy storage type element, and the processing circuit 26 stores the light from the light receiving elements constituting the light receiving element array 24. A multiplexer 30 for extracting the stored energy is provided.

The processing circuit 26 also includes a multiplexer 30.
A hold circuit 32 for sample-holding the signal taken out by the A / D converter, an A / D converter 34 for A / D converting the signal from the hold circuit 32, and an A / D converter.
And a central processing unit 36 including a microcomputer that processes the converted signal to perform color calculation.

Next, the light emitting circuit 12 will be described. In this light emitting circuit 12, the same output terminal of the trigger coil T as in FIG. 4 is connected to the trigger electrode 14A in the xenon lamp 14, and a current limiting resistor R ₀ is provided instead of the inductance L in FIG. is there. Further, the main capacitor C ₀ has a smaller capacity than that in FIG.

Specifically, the xenon lamp 14 is shown in FIG.
In the case of the same specifications as the xenon lamp Xe, the peak current is set to 2000 A by the current limiting resistor R _0, and the capacity of C ₀ is 5000 A at the peak current and 50 μS in the discharge time in the case of the light emitting circuit of FIG. However, in this embodiment, the peak current is 2000 A and the discharge time is 15 μS.

Next, the operation of the apparatus of the above embodiment will be described. The light emitting circuit 12 causes the xenon lamp 14 to emit light with a peak current of 2000 A and a discharge time of 15 μS, as shown in FIG. At this time, discharge and light emission are performed a plurality of times (2 or 3 times is preferable) for one measurement.

The pulsed light from the xenon lamp 14 becomes diffused light in the diffusion chamber 28 to diffusely illuminate the measurement sample 16, and the vertically reflected light from the measurement sample 16 is guided to the optical system 22 through the window 28A. . The pulsed light that has passed through the optical system 22 is
The light is split by the light splitting means 20 and received by the light receiving element array 24.

Since the light receiving element array 24 is composed of energy storage type elements, the xenon lamp 14
The received light energy from a plurality of times of light emission from is accumulated in each light receiving element.

The energy accumulated by a predetermined number of times of light emission is taken out for each element by the multiplexer 30 in the processing circuit 26, sampled and held by the hold circuit 32, and then the signal is A / D converted by the A / D converter 34. It is converted and input to the central processing unit 36.
The central processing unit 36 calculates a predetermined color based on the input signal and displays the result on a display unit (not shown).

In this embodiment, the xenon lamp 14 is discharged at a peak current which is less than half of the conventional peak current, so that the electrodes of the xenon lamp 14 are worn very little and the lamp life is greatly extended. Moreover, since the output light intensity is not too high, the pulsed light does not pass through the measurement sample.

Further, since the discharge time is reduced to ⅓ or less of the conventional value by reducing the capacity of the main capacitor C ₀ , the xenon plan 14 causes a spectrum shift for each light emission even if the peak current is reduced. Never.

Furthermore, even if the xenon lamp 14 has a slight variation in the light emission intensity, the energy generated by a plurality of times of light emission is accumulated in each element of the light receiving element array 24 to obtain information. As a result, variations in emission intensity are averaged, and more accurate measurement is possible.

In the above embodiment, the xenon lamp 14 is used.
Supply peak current to 2000A, discharge time 15μS
However, the present invention is not limited to this, and if necessary, according to the specifications of the xenon lamp, about 1/2 or less of the normal peak current is set as the energization peak current,
Further, the discharge time may be 50 μS at the maximum and 5 μS at the minimum so that the energy accumulated in the light receiving element by one light emission becomes 2 to several times of the required amount.

In the above embodiment, the irradiation lamp of the sample to be measured is a xenon lamp and the spectroscopic means is a concave grating. However, the present invention is not limited to this, and other lamps and spectroscopic means may be used. Good.

[Brief description of drawings]

FIG. 1 is a block diagram including a partial optical system diagram showing an embodiment of a colorimeter according to the present invention.

FIG. 2 is a circuit diagram showing a light emitting circuit in the same embodiment.

FIG. 3 is a diagram showing the relationship between the peak current passed through the xenon lamp and the discharge time in the same example.

FIG. 4 is a circuit diagram showing a conventional xenon lamp light emitting circuit.

FIG. 5 is a diagram showing a relationship between a current-carrying peak current and a discharge time in the conventional xenon lamp.

[Explanation of symbols]

10 ... colorimeter 12 ... light-emitting circuit 14 ... xenon lamp 16 ... sample 18 ... pulse light source 20 ... spectroscopic unit 22 ... optical system 24 ... light-receiving element array 26 ... processing circuit 30 ... multiplexer T ... trigger coil C ₀ ... main capacitor R ₀ … Current limiting resistance

Claims (1)

[Claims] 1. A measurement sample is irradiated with pulsed light from a pulsed light source, reflected light or transmitted light from the measurement sample is received by a light-receiving element array through a spectroscopic means, and color is calculated by the output of the light-receiving element. In a colorimeter equipped with a processing circuit,
The light receiving element is an energy storage type element, the processing circuit is configured to extract the energy stored in the light receiving element for each light receiving element, and the pulse light source emits light for one emission time of 50 to 5 μS. In addition, the energy accumulated in the light receiving element by one light emission is set to be 2 to several times the minimum energy required for color calculation in the processing circuit. Colorimeter.