JPH0625735B2 - Zero correction device in optical measuring instrument - Google Patents

Description

TECHNICAL FIELD The present invention relates to a zero correction device in various optical measuring instruments such as a differential refractometer and a spectrophotometer. That is, most of the detection mechanisms in the optical measuring device are of a system that converts the difference between the energy level of light before the start of measurement and the energy level of light at the time of measurement into an electric signal. Therefore, in this case, as a matter of course, it is necessary to set the output before the start of measurement to display zero, and the mechanism for setting this output to zero is called a zero correction mechanism (device).

<Prior art> As a mechanism for automatically performing this kind of zero correction, an optical auto-zero method in which light incident on a photoreceptor is controlled by an optical correction mechanism and a voltage corresponding to an error voltage before the start of measurement are externally supplied. There is an electrical auto-zero method that cancels by giving it from. Since the optical auto-zero method can always make the light energy the same before the measurement is disclosed, the linearity and linearity of the calibration curve showing the relationship between the sample concentration and the output at the time of measurement accompanying the fluctuation of the energy level Although it has the advantage that the range is always constant, the optical correction mechanism for adjusting the amount of light incident on the photoreceptor and the optical axis must be driven by the control motor, so it takes time to perform zero correction work and it can be driven quickly. There is a problem that the accuracy of zero correction is reduced.
Also, in the electric auto-zero method, the zero correction time is fast, but since the optical energy level balance correction is not performed,
There is a problem that it is necessary to correct the measured value with the fluctuation of the calibration curve.

<Problems to be Solved by the Invention> The present invention has been made in view of such conventional problems, and the time required for zero correction can be greatly reduced as compared with the conventional optical auto-zero method. At the same time, the accuracy of zero correction can be made comparable to the conventional optical auto-zero method, and the balance of the optical energy level is not always the same before starting the measurement. An object of the present invention is to provide a zero correction device in an optical measuring device that can be held constant.

<Means for Solving the Problems> In order to achieve the above object, the zero correction device in the optical measuring instrument of the present invention electrically connects the control circuit of the optical correction mechanism for controlling the light incident on the photoreceptor to the photoreceptor. In addition to that, an electrical zero correction circuit for externally applying a voltage corresponding to the error voltage before the start of measurement to cancel the voltage is connected to the output side of the control circuit.

<Examples> Examples of the present invention will be described below with reference to the drawings.

Fig. 1 shows an example of a differential refractometer, and Fig. 3 shows an example of a spectrophotometer. This value also shows the difference between the energy level of light before the start of measurement and the energy level of light at the time of measurement. It will be easily understood from the following description that the device of the present invention can be applied to any optical measuring device having a detection mechanism for converting into a signal.

In FIG. 1, reference numeral 1 in the drawing is a light source lamp, and light P from this light source lamp 1 passes through a sample cell 2, is reflected by a reflecting mirror 3 installed behind the sample cell 2, and passes through a glass plate 4 to receive a light receiver 5 Incident on. The light energy incident on the light receiver 5 is converted into electric energy by the light receiver 5, amplified by the control circuit 6 and output to the electrical zero correction circuit 7. In the optical system from the reflecting mirror 3 to the light receiving body 5, a control motor 8 is driven by a signal from the control circuit 6 to move the angle of the glass plate 4 to move the optical axis incident on the light receiving body 5 in parallel. Optical zero correction is performed before the start of measurement. That is, the optical correction mechanism that controls the light P ₁ incident on the light receiver 5 is composed of the glass plate 4, the control motor 8 for moving the glass plate 4, and the control circuit 6 for driving the control motor 8. The control circuit 6 is electrically connected to the light receiving body 5, and the light P ₁ incident on the light receiving body 5 composed of the sample side light receiving element and the reference side light receiving element in the state before the measurement is compared with the sample side light receiving element. When the light is not evenly incident on the side light receiving element, a signal corresponding thereto is output from the light receiving body 5 and applied to the control circuit 6, and the signal causes light to be transmitted to the sample side light receiving element and the control side light receiving element. The glass plate 4 is moved through the control motor 8 so that the light is evenly incident, and the optical axis incident on the light receiver 5 is moved in parallel to perform optical zero correction.

Next, the electrical zero correction circuit 7 is connected to the output side of the control circuit 6 to perform electrical zero correction. This electrical zero correction circuit 7 is a circuit for canceling by externally applying a voltage corresponding to the error voltage before the start of measurement. Specifically, as shown in FIG. The comparator 20 for discriminating the magnitude of the voltage (plasma minus), the up / down counter 21 for adding / subtracting the voltage according to the discrimination of the comparator 20, and the differential amplifier 22 for canceling the error voltage. Composed of and. However,
When the light P _{1 that} has entered the photodetector 5 before the start of measurement is not evenly incident on the sample-side photodetector and the control-side photodetector, the photodetector 5 outputs a corresponding signal. , That signal to one input terminal of the differential amplifier 22
It is input from 23 and its output is input to the comparator 20. The comparator 20 compares and determines the difference between the voltages of the input signals with respect to zero V on the HIGH side or the LOW side, and according to the determination result, the up / down counter 21
Therefore, when it is HIGH, addition is performed, and when it is LOW, subtraction is performed. When the + IN and -IN inputs are balanced, the up / down counter 21 balances and maintains a balanced state, and outputs it to the differential amplifier 22. If the up / down counter 21 is latched when it is in a balanced state, its output voltage will continue to hold this voltage even if the input voltage changes until the latch voltage is released. With this, electrical zero correction is performed.

Further, FIG. 3 shows an example of a spectrophotometer. In the figure, 9 is a half mirror for distributing the incident light P to the sample side light receiving body 5a and the control side light receiving body 5b, and 10 and 10b are Photoreceptors 5a, 5b
It is a diaphragm (slit) for adjusting the amount of light incident on, and the same reference numerals as those in FIG. 1 denote the same constituent members. In this example, the optical correction mechanism for controlling the light P incident on the light receivers 5a and 5b is composed of a half mirror 9, a control motor 8 for moving the half mirror 9, and a control circuit 6 for driving the control motor 8. It On the other hand, when the amount of light incident on the sample-side photoreceptor 5a and the control-side photoreceptor 5b is not equal in the state before the start of measurement, a signal corresponding to that is output to the control circuit 6 and the sample-side photoreceptor 5a. Control side photoreceptor 5b
Optical zero correction is performed by changing the reflection angle of the half mirror 9 via the control motor 8 so that the energy (light amount) of the light incident on and becomes uniform. Even when a single light receiving body that does not require the control side light receiving body 5b is used, optical zero correction can be performed by changing the amount of light reaching the sample cell 2 in the same manner. Then, the output of the control circuit 6 is output through the electrical zero correction circuit 7 described above.

<Effects of the Invention> Since the zero-correction device in the optical measuring instrument of the present invention is configured in this way, if the zero-correction operation is performed before the start of measurement, the optical correction mechanism (optical auto-zero mechanism) and the electrical zero-correction circuit (electric Automatic zero mechanism), so that electrical zero correction can be performed while maintaining optical balance, and the output can be swiftly and accurately corrected without causing a deviation in output magnitude caused by optical imbalance. Correction can be done. In other words, the optical correction mechanism works only to restore the optical balance within the range where the calibration curve does not change, so the speed limit for improving the accuracy is greatly relaxed, and as a result, the time required for zero correction is reduced. It can be greatly shortened compared to the optical auto-zero method. Further, since the correction range of electrical zero can be limited to the correction range of optical zero, the accuracy of zero correction can be maintained at the same level as or higher than that of the conventional optical auto-zero method.

Moreover, since the basic zero correction is performed by the optical correction mechanism (optical auto-zero mechanism), the balance of the optical energy level is not always the same before the measurement is started, and the linearity of the calibration curve and the linearity range are always maintained. It can be held constant, and there is no risk of causing a change in the calibration curve caused by poor optical balance due to the accumulation of repeated corrections. Fourth
The figure is a graph showing this effect, the vertical axis shows the magnitude of the output, the horizontal axis shows the magnitude of the deviation of the optical balance, of the output signal obtained by the sample concentration caused by the poor optical balance. It is understood that there is no change in size.

Therefore, the intended purpose can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram showing an embodiment of an electrical zero correction circuit according to the present invention, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a schematic diagram for explaining the effect of the device of the present invention. In the figure, 5 and 5a and 5b are photoreceptors, 6 is a control circuit, and 7 is an electrical zero correction circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Nagai 2985 Negishi, Kawaguchi City, Saitama Prefecture Elma Kawaguchi Factory (72) Inventor Tokuto Fukunaga 2985 Negishi, Kawaguchi City Saitama Prefecture Elma Kawaguchi Factory (56) (56) References Japanese Patent Laid-Open No. 51-98090 (JP, A)

Claims (1)

[Claims] 1. A control circuit of an optical correction mechanism for controlling light incident on a photoreceptor is electrically connected to the photoreceptor, and a voltage corresponding to an error voltage before the start of measurement is provided on the output side of the control circuit. A zero-correction device in an optical measuring instrument, characterized in that an electrical zero-correction circuit for externally applying and canceling is connected.