JPS58193439A - Absorptiometer - Google Patents

Abstract

PURPOSE:To attain a simplified structure and high performacne by a method wherein a semiconductor light emitting device of single-wavelength property is driven by a pulse voltage generating power source. CONSTITUTION:When pulse voltage is supplied to an LED of a light source section 6 from a power source circuit 5 comprising a pulse voltage generating circuit, the LED is lit up intermittently in accordance with the frequency of the supply voltage. The projected light becomes a parallel beam through a lens 9 and is then irradiated to a sampled cell 3. With the LED of single-wavelength property being used as one of the light source section 6, a filter for selecting wavelength, a grating, etc. can be dispensed with as compared with the case using an LED of overall-wavelength light emitting property. Use of the power source circuit comprising a pulse voltage generating circuit also eliminates the need of another mechanism such as a rotary sector. Thus, it becomes possible to attain an absorptiometer with a simplified structure and high performance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in spectrophotometers that perform analysis by measuring the absorbance of colored substances.

Conventionally, the detection section of a spectrophotometer that utilizes light absorption of a color-forming substance has a light source 1, a metal interference filter 2 for wavelength selection (or wavelength selection using a prism-slit, or ), sample cell 3, detector (consisting of a photoelectric conversion element, a conversion amplifier for its output, an output indicator, etc.) 11
1, most of them have a basic configuration, and a tungsten lamp, halogen lamp, mercury lamp, etc. are used as the light source. These light sources emit light over a wide range of wavelengths, so you can freely select the desired wavelength. However, tungsten lamps and halogen lamps have short lifespans, and their brightness changes significantly over time. In addition, in order to select the desired wavelength, an expensive and mechanically complex wavelength selection optical system (filter, diffraction grating, prism-slit, etc.) must be provided. As required, etc.
Its maintenance requires a great deal of effort and expense.

The present invention uses a semiconductor light emitting device (light emitting diode, I] ID, hereinafter simply referred to as LED) that emits light of a single wavelength that matches the absorption wavelength range of the test substance component as a light source. Compared to light sources such as 10-gen lamps, it has a longer lifespan and is extremely easy to maintain.
Since the synchrotron radiation has a single wavelength, that is, it has monochromatic properties, there is no need for a complicated optical system for wavelength selection.
By intermittent lighting of the CD light source using a pulsed power source, we provide a spectrophotometer with excellent performance, such as obtaining the optical chopper effect similar to the rotating sector in a conventional spectrophotometer using a tungsten lamp or halogen lamp as a light source. It is possible.

FIG. 2 is a sectional view showing an embodiment of a detection section of an absorption photometer using a single wavelength characteristic LID according to the present invention.

In the figure, 6 is a light source unit using an LED, 7 is a light source unit block for attaching the light source unit 6 to the sample cell, 9 is a lens for irradiating light from the LED in parallel, and 9 is a photoelectric conversion element 10
It is a condenser lens attached to the light receiving block // that focuses light on the light source block 7, and when it is necessary to perform particularly high-precision measurements, a gold jll interference filter g is attached to the lens 9 of the light source block 7. It can also be worn on the front.

When a pulse voltage is supplied to the LED of the light source part B from the power supply circuit S consisting of a pulse voltage generation circuit, the LED lights intermittently according to the frequency of the supplied voltage, and the projected light is converted into a parallel light beam by the lens 9. , the sample cell 3 is irradiated.

Then, it is absorbed by the sample in the sample cell 3, and the light is attenuated and reaches the photoelectric conversion element IO in the light receiving block 11,
The received light is converted into an electrical signal according to its intensity. This electrical signal is amplified and rectified in synchronization with the intermittent pulses of the light source, and then detected by a meter or the like as an electrical signal corresponding to the sample concentration.

Here, if you use the LIC'D of the light source part B with single wavelength emission characteristics, ``compared to the one with full wavelength emission characteristics,
There is no need for wavelength selection filters, diffraction gratings, etc., and the use of a power supply circuit consisting of a pulse voltage generation circuit eliminates the need for mechanisms such as rotating sectors, resulting in a simplified structure and a high-performance spectrophotometer. can be configured. Various types of LEDs with single wavelength emission characteristics are commercially available, and can be selected depending on the purpose and the light absorption characteristics of the sample.
(1... Figure 3 shows an example of the light absorption characteristics of creatinine viclat according to the present invention, measured using a green single-wavelength LED as a light source.

In this example, the sample creatinine vicrate has been color-shifted to red, and its maximum absorption wavelength range is around 1I90XIOrn, which only partially matches the emission wavelength range of the green single-wavelength LED, as shown in the figure. However, it can be seen that the relationship between the creatinine concentration in creatinine picrate and the absorbance has sufficient linearity as shown in FIG. That is, even if the sensitive wavelength range of the substance component to be measured is part of the emission wavelength range of the light source, as long as there is a matching part, concentration measurement can be performed with sufficient linearity.

According to the present invention, by using an LID with a single wavelength emission characteristic as a light source for an absorption photometer, its configuration is significantly simplified.Moreover, since the LICD can be lit in pulses, it can be used in combination with a synchronous rectifier circuit to This eliminates the need for mechanical devices such as sectors, which greatly improves the performance of the spectrophotometer.

LICD has not yet been used as a light source for an absorption photometer, but various high-performance and inexpensive LEDs are currently on the market, and materials are easily available.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a part of the structure of the detection section of a conventional spectrophotometer, FIG. 2 is a sectional view showing an embodiment of the structure of the detection section of the spectrophotometer according to the present invention, and FIG. The figure shows the emission wavelength characteristics of LICE with green single wavelength emission characteristics and the absorbance wavelength characteristics of creatinine picrate as a sample example. Figure 7 shows the light absorption of the present invention using LICD with green single wavelength emission characteristics as a light source. FIG. 2 is a diagram illustrating concentration-absorbance characteristics when the creatinine concentration in creatinine picrate is measured using a photometer. /...Light source, -...Metal interference filter, 3...Sample cell, Da...Detector, S...Pulse voltage supply power supply circuit\6.
・Light source block using LED, ri...
- Gold 11 interference filter, 9...lens, 9'...condenser lens, IO...photoelectric conversion element, /l...light receiving block.

Claims (1)

[Claims] (1) In a spectrophotometer that is equipped with a photoelectric conversion element that irradiates a sample cell with light from a light source, receives the light absorbed by the sample substance in the cell, and converts the amount of light into an electrical signal, the light source part 1. A spectrophotometer, wherein the light source comprises a semiconductor light-emitting element with a single wavelength characteristic, and the power supply circuit for the light-emitting element that causes the light-emitting element to emit light comprises a pulse voltage generation circuit.