JPH0577972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a spectrophotometer, and more particularly to a position adjustment mechanism for a light source in a spectrophotometer.

(Prior Art) In measurements using a spectrophotometer, it is desirable to make the light emitted from a light source enter the spectrometer as efficiently as possible in order to improve measurement sensitivity.
For this reason, when assembling and adjusting the spectrophotometer at the factory, optical members such as mirrors that guide the light from the light source to the spectrometer must be installed so that the light from the light source enters the spectrometer in the most efficient manner. Although it is common practice to adjust the mounting position, if the light source is replaced due to deterioration of the sunlight source, the mounting position of the light source may shift. However, in such a case, it is difficult to determine whether or not the light source position has shifted, and if it has shifted, to readjust the light source so that it most efficiently enters the spectroscope. For this reason, some spectrophotometers are equipped with an adjustment mechanism as shown in FIG. This adjustment mechanism serves both as a switching mechanism between the two internal light sources of the spectrophotometer and as an adjustment mechanism for making the light from each light source enter the spectrometer most efficiently. In this figure, D is a first light source, for example a deuterium lamp, W is a second light source, for example a tungsten lamp, and 1 directs the light emitted from these sources onto the input slit S1 of the spectrometer M. A condensing mirror that condenses light, which can be rotated about a point O on an axis perpendicular to the plane of the diagram, and is rotated by a motor when using the light from the first light source D. In this case, the normal line at the point O of the condenser mirror is directed in the N1 direction, and when the light from the second light source W is used, it is directed in the N2 direction of the normal line, thereby switching between the two types of light sources. P is a photodetector that receives the light beam emitted from the exit slit S2 of the spectrometer M. For example, when using the first light source D, the center normal of the condensing mirror 1 should be oriented in the N1 direction, and the spectrometer should be adjusted to make the light from the light source enter the spectrometer in the most efficient manner. and set it to the N1 position.
The collector mirror 1 is rotated over a certain angular range around the direction, and the output of the photodetector P is maximized.
The direction of the condenser mirror is detected and the direction of the condenser mirror is set in that direction. This adjustment operation is automatically performed by a control device built into the spectrophotometer as an initial operation when the spectrophotometer is powered on.

(Problems to be Solved by the Invention) As mentioned above, in a spectrophotometer, adjustments are made during assembly and adjustment at the spectrophotometer factory in order to make the light from the internal light source of the spectrophotometer most efficiently enter the spectrometer. However, there is a problem in that it is difficult to readjust the light source when replacing the light source.In the conventional device shown in Figure 5, the above-mentioned adjustment is automatically performed when the spectrophotometer is powered on, so when the light source is replaced, However, the initial operation when the power is turned on is to search for the optimal position of the light source, so there is a problem that the initial operation takes time, and it also requires measuring the spectral characteristics of an arbitrary light source. Although an internal light source is not required in such cases, an internal light source is required to complete the initial operation when the power is turned on, and the internal light source must be removed after the initial operation is completed, making it difficult for the operator to However, there is a problem in that the starting operation of the spectrophotometer becomes very troublesome.

The present invention aims to solve the above-mentioned problems in spectrophotometers.

(Means for Solving the Problem) A light source or an optical element that guides light from the light source to a spectroscope is made variable in position, and a pulse motor for changing the position of the variable-position light source or optical element; a position detecting means for detecting a reference position of the light source or the optical element; and a position detecting means for detecting a reference position of the light source or the optical element; and when the photodetector output of the spectrophotometer reaches a maximum while driving the variable-position light source or the optical element from the reference position. By detecting the number of driving pulses of the pulse motor and writing the number of pulses in the memory, the position-variable light source or optical element is written in the memory from the reference position by turning on the spectrophotometer and the appropriate position detection operation mode. The spectrophotometer is provided with a light source having an initial operation mode in which the light source is moved by driving the pulse motor by a number of pulses, or a position adjusting means for an optical element that introduces light from the light source into the spectrometer.

(Function) In the conventional example shown in Fig. 5, the condenser mirror is rotated to make adjustments so that the light from the light source enters the spectrometer most efficiently, but this adjustment requires adjusting the position of the light source. It is also possible by In the case of the conventional example above, the initial operation when the spectrophotometer is turned on is to move the condenser mirror within a certain range each time to search for the position where the output of the spectrophotometer's photodetector is maximum. Although the initial operation takes time, in the case of the present invention, there is a means for detecting the reference position of the light source or the optical element that introduces the light from the light source into the spectrometer, and the initial operation is performed by moving the light source or the optical element to the reference position. Since the actuator is driven by a predetermined amount from the position stored in the memory in advance, the time required for the initial operation is shortened compared to searching for an appropriate position one by one. The data stored in the memory is determined by detecting the amount of drive from the reference position of the light source or the optical element until the output of the photodetector of the spectrophotometer reaches its maximum in the proper position adjustment operation mode. Since this drive amount is stored in memory, the light source or optical element can be set to the appropriate position by the initial operation each time the same light source is used, and when the light source is replaced, the You only need to perform the proper position detection operation once, and the proper position can be readjusted automatically when you replace the light source, so even when using an external light source,
Since the internal light source does not need to be lit for initial operation,
The spectrophotometer can be started just as if using an internal light source.

(Embodiment) FIG. 1 shows a main part of an embodiment of the present invention. This embodiment is equipped with a first light source D such as a deuterium lamp and a second light source W such as a tungsten lamp as internal light sources, and switching between these two light sources is performed by rotating the condenser mirror 1. This point is the same as the conventional example shown in FIG. 2 is a pulse motor for rotating the condensing mirror 1, and 3 is a speed reducer for decelerating the rotation of the pulse motor and transmitting it to the rotating shaft 4 of the condensing mirror 1. A pin 5 protrudes from the rotating shaft 4, and the pin 5 is detected by a photoelectric detector 6 fixed to the device on the side of the rotating shaft, and the condenser mirror 1 is rotated. The position of the condenser mirror 1 when the pin 5 is detected by the photoelectric detector 6 becomes the reference position. Since the position detection accuracy of the reference position detection means consisting of the pin 5 and the photoelectric detector 6 is not very high, in this embodiment, one excitation pattern of the pulse motor 2 (for example, every 8 steps in 1-2 phase excitation) is used. ), and the signal of the specific excitation pattern that is emitted first after the rise (or fall) of the detection signal of pin 5 in the photoelectric detection means is used as the reference position detection signal. 7 biases the shaft 4 in one direction to reduce the speed reducer 3
This is a spring that eliminates the bump caused by
8 is a limit switch which detects the initial position of the condenser mirror 1 when the pin 5 hits it.

FIG. 2 is a block diagram showing the overall configuration of the spectrophotometer according to the above embodiment. L denotes a light source section, which is composed of the various parts shown in FIG. M is a spectrometer and C
is a sample chamber, through which the light emitted from the spectrometer M passes, and a sample can be placed on the optical path. The PM consists of a photodetector, an amplifier, etc. that receives the spectrometer output light that has passed through the sample chamber C in the photometry section, and the control section CPU takes in the photometry output of the photometry section PM and performs data processing and control of the entire device. Controls measurement operations. Reference character K is an operation unit that inputs various data, instructs the operation mode, instructs the start of operation, etc. to the control unit CPU by key operations. DSP displays measurement results on a display device.

When performing normal measurements with the above device, the operator first presses the power on key. Then the control section
The CPU supplies power to the light source section, spectrometer, photometry section, display section, etc., performs initial operation of the light source section, and then puts the entire device into a standby state. Thereafter, the operator specifies the type of light source to be used by operating keys on the operation section K, specifies the measurement wavelength range, etc. When the operator sets the sample in the sample chamber C and presses the start key on the operating section, the measurement operation begins. When performing the operation for detecting the proper position of the light source, the operator presses a key on the operating section K that instructs the operation mode for detecting the proper position of the light source. Then, the proper position of the condensing mirror 1 is detected for each of the two light sources D and W, and the data of the drive amount of the pulse motor 2 corresponding to each light source from the reference position is stored in the built-in nonvolatile memory.

Figure 3 shows the initial operation of the light source unit described above.
This is a flowchart showing the operation of the CPU. This operation starts when the power on key is pressed, first driving the pulse motor to return the rotating shaft 4 of the condenser mirror 1 to its initial position (a), then driving the pulse motor in the forward direction (rotation). ), check whether a pin detection signal is output by the photoelectric detector 6 (c), rotate the pulse motor forward until the pin detection signal is output, and step (c) is completed.
When this step becomes YES, check whether the pulse motor is in the specified excitation pattern or not, and when this step becomes YES, count the pulse motor drive pulses.
Checks whether the count of the counter built into the CPU reaches a predetermined count value for the selected light source, which is stored in advance in non-volatile memory for the selected light source, until the judgment in the same step becomes YES. The pulse motor is driven, and the drive pulses of the motor are counted by the counter (f), and when the determination in step (e) becomes YES, the pulse motor is stopped (g) and the initial operation is completed. When measuring using an external light source, the same initial operation as above is performed, and in step (e), the count value when either light source D or W, for example W, is selected is used.

Figure 4 is a flowchart of the operation of the CPU during proper light source position detection operation, and this operation causes the CPU's built-in non-volatile memory to store the count value used in step (e) in the operation shown in Figure 3. It will be done. When the key for proper position detection of the light source is pressed, the pulse motor is driven to return the condenser mirror 1 to its initial position (a), the light source W is turned on (b), and the pulse motor is driven in the forward direction (a). c) Next, check the presence or absence of the pin 5 detection signal from the photoelectric detector 6, and
When is detected, it is checked whether the excitation pattern of the pulse motor 2 is a predetermined pattern (e), and if the judgment in this step becomes YES, the CPU built-in counter starts counting the drive pulses of the pulse motor 2 (f).
Then, the pulse motor 2 is driven to rotate the focusing mirror 1 to near the appropriate position with respect to the light source W.
(g) After that, the photometric output of the photometric unit PM is sampled every step of driving the pulse motor 2, and the maximum value of the same output is detected (for example, by comparing the latest sampling data with the previous sampling data, It is assumed that the maximum value is detected when the data becomes equal to or smaller than the previous sampling data (H), and when the maximum value is detected, the counter count value at that time is stored in the CPU's built-in non-volatile memory. be stored as a predetermined count value for
(li) Continue driving the pulse motor, continue counting pulse motor drive pulses, stop sampling of photometric output, turn on light source D (nu), until the condenser mirror 1 approaches the appropriate position relative to light source D. When this happens, sampling of the output of the photometry section starts again (ru), and the operation ends after going through the same steps (o) and (wa) as in (ch) and (li) above. The operation shown in FIG. 4 only needs to be performed once, such as when replacing the light source.

(Effects of the Invention) According to the present invention, in the initial operation at the time of measurement, the proper position of the light source or the optical element that guides the light from the light source to the spectrometer is not searched for, but the amount of motor drive from the reference position to the proper position is determined in advance. Since the position of the light source or the above-mentioned optical element is set by memorizing the drive amount from the reference position and setting the position of the light source or the above-mentioned optical element, the initial operation can be completed in a short time, improving the efficiency of analysis. The amount of motor drive to reach the proper position is stored in memory during the light source or optical element proper position detection operation, so even after replacing the light source, once you have performed the light source, etc. proper position detection operation, you can repeat the above initial operation again. The proper position of the light source, etc. is set in this way, and there is no need for troublesome readjustment after replacing the light source.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts of an apparatus according to an embodiment of the present invention;
Figure 2 is a block diagram showing the whole of the same embodiment;
This figure is a flowchart of the initial operation in the above embodiment, FIG. 4 is a flowchart of the proper position detection operation, and FIG. 5 is a schematic plan view of an example of the conventional device. 1...Condensing mirror, 2...Pulse motor, 3...Reducer,
4... Axis, 5... Pin, 6... Photoelectric detector, 8... Limit switch, D... First light source, W... Second light source, L
...Light source section, M...Spectrometer, C...Sample chamber, PM...Photometry section, CPU...Control section, K...Operation section, DSP...Display section.

Claims (1)

[Claims] 1. A light source or an optical element that guides light from the light source to a spectroscope is variable in position, a pulse motor for changing the position of the variable light source or optical element, and a reference for the variable position light source or optical element. a position detecting means for detecting a position, and detecting the number of pulse motor drive pulses when the photodetector output of the spectrophotometer reaches a maximum while driving the variable position light source or optical element from the reference position. Then, by entering the proper position detection operation mode in which the number of pulses is written in the memory and turning on the power of the spectrophotometer, the pulse motor is activated to move the variable position light source or optical element from the reference position by the number of pulses written in the memory. A spectrophotometer comprising a light source having an initial operation mode in which the light source is moved by driving, or a position adjusting means for an optical element that introduces light from the light source into a spectrometer.