JPS61237026A - Switching of filter - Google Patents

Abstract

PURPOSE:To insert a desired filter into an optical path, by forming an origin hole with the diameter smaller than any filters on a turrent fitted with a plurality of filters to make the reference position point detecting it utilizing a measuring system. CONSTITUTION:When the type of filters is specified, a microcomputer 19 sets the gain of an amplifier 17 so that the output signal as obtaind when the light passing through an origin hole 30 is measured will approach the saturation value of the amplifier 18. The output signal of a photo detector 14 digitized with an A/D converter 18 after amplified with the amplifier 17 and inputted into the microcomputer 19 which compares the measured value with a specified value alpha and the measured value is larger than alpha when the origin hole 30 enters an optical path 16. At this point, the step feeding of a turret 15 is stopped. With this reference position A as origin, the number of steps at which individual filters 27-29 are inserted into the optical path 16 are memorized into a ROM of the microcomputer 19. With such an arrangement, a drive pulse corresponding to the filter selected is outputted to a pulse motor 21 from the microcomputer 19 to insert a desired filter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a filter switching method used in optical equipment such as a colorimeter.

[Conventional technology]

When performing colorimetric photometry on a sample using a colorimeter, a filter is inserted between the sample and a photodetector to extract only light in a predetermined wavelength range for photometry. When measuring light in different wavelength ranges, a turret equipped with bipolar filters is used, and the turret is rotated by a pulse motor to insert the desired filter onto the light beam. Conventionally, a single small hole is formed on the outside of the filter to indicate the origin position, and an origin detection sensor is provided to detect this origin hole.
The number of steps of the pulse motor required to insert each filter into the optical path of the measurement system is determined in advance using this origin hole as a reference, and when switching filters, the turret is rotated to detect the origin hole, and this After detecting the hole, a preset number of drive pulses are generated to rotate the pulse motor, and a desired filter is inserted into the optical path of the measurement system. However, this filter switching method requires an origin detection sensor for detecting the origin hole, which has the disadvantage of making the structure complicated and increasing costs.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a filter switching method that has a simple structure and can reduce costs by detecting the origin hole using a measurement system.

[Means for solving problems]

In order to achieve the above object, the present invention is such that an origin hole having a smaller diameter than the filter is formed in the turret and the origin hole is detected using a measuring system.

There are two ways to detect the origin hole: one is to utilize the difference in transmittance between the origin hole and the filter, and the other is to detect the size of the origin hole. I can do it.

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

(Example) In FIG. 1 showing a chemical analysis device, a chemical analysis slide 1 is for quantifying a test component present in a liquid sample, and includes a sheet-shaped measuring element 2 and a measuring element 2. The measuring element 2 is composed of a slide frame 3 for storing and holding.The measuring element 2 has at least a reagent holding layer coated on a transparent support, onto which a liquid sample is spotted. The completed chemical analysis slide 1 is placed on a thermostatic plate 4 and incubated at a predetermined temperature, for example, 37°C, for a certain period of time.This incubation allows the test components and reagents contained in the liquid sample to be sufficiently absorbed. It reacts and develops a color at a concentration that corresponds to the content of the test component.

A density/measuring section 5 is provided below the thermostatic plate 4, and the density measuring section 5 measures the color density of the chemical analysis slide 1. After this measurement, the push-out lever 6 moves forward to push out the chemical analysis slide 1 in the normal position and place the receiver in the tray 7. A white part 6a to which ceramic or the like is attached is provided on the lower surface of the push lever 6. When the push lever 6 is in the forward position, the reflected light is measured by the density measuring part 5, and the obtained density is used as the reference density. used.

The concentration measurement section 5 includes a dark box 10, in which a plurality of lamps 11 are arranged concentrically, and illuminate the measurement element 2 at an angle of 45 degrees through a heat shielding filter 12. The light reflected by the measurement element 2 passes through the heat shield filter 12 again and then enters the lens 13, and an image of the measurement element 2 is formed on the photodetector 14. A turret 15 holding a plurality of interference filters (hereinafter simply referred to as filters) is arranged between the lens 13 and the photodetector 14. A desired filter is inserted into the optical path 16, and a predetermined filter is inserted into the optical path 16. Only light in the wavelength range is incident on the photodetector 14.

The output of this photodetector 14 is amplified by an amplifier 17, then converted to a digital signal by an A/D converter 18, and input to a microcomputer 19. The gain of this amplifier 17 is adjusted by a microcomputer or computer 19 depending on the selected filter. The turret 15 is rotatably held by a shaft 20, and a gear 15a is formed on the outer periphery of the turret 15. This gear 15a meshes with a gear 23 that is supported on a rotating shaft 22 of a pulse motor 21. The microcomputer 19 sends a driving pulse to the driver 24 to rotate the pulse motor 21, thereby rotating the turret 15 and inserting a desired filter into the optical path 16.

Further, this microcomputer 19 sends a drive signal to the drive unit 25 to operate the extrusion plate 6.

As shown in FIG. 2, in the turret 15, bipolar filters 27 to 29 that transmit different wavelength ranges and an origin hole 30 having a diameter smaller than these are arranged on a concentric circle. In this embodiment, the filter 27 has a dominant wavelength of 510
The filter 28 has a main wavelength of 540 nm.
The filter 29 transmits light having a dominant wavelength of 600 nm. Note that the photodetector 14 is also shown for convenience.

FIG. 3 shows the output of the photodetector 14 when the turret 15 is rotated with the white part 6a of the push lever 6 inserted into the optical path 16, and the vertical axis is the output of the photodetector 14. The horizontal axis is the number of stethos of the turret 15 (the number of drive pulses of the pulse motor 21). Origin” hole 3
0 can be detected by using the difference between the measured values of the origin hole 30 and each filter, and by detecting from the difference in size between the origin hole 30 and each filter. In the former case, the output α between the origin hole 30 and the output of the filter 29 is used as the reference output, and in the latter case, the output β is used, which is sufficient to eliminate the effects of dark current etc. It will be done. Here, the size of each filter is 26 steps, and the light-shielding section located between them is 22 steps.

Further, the size of the origin hole 30 is 4 steps, and the size of the photodetector 14 is about 6 steps.

FIG. 4 shows the filter switching procedure in an embodiment in which the origin hole is detected only from the output of the measurement system. When you specify the type of filter, the microcomputer 19
The gain of the amplifier 17 is set so that the output signal when the light transmitted through the origin hole 30 is measured is close to the saturation value of the amplifier 18. Next, the drive unit 25 is operated to advance the push lever 6 and insert the white part 6a into the optical path 16. This white portion 6a is illuminated by a lamp 11, and the reflected light is photoelectrically converted by a photodetector 14. The output signal of this photodetector 14 is amplified by an amplifier 17 and then
It is converted into a digital signal by the D converter 18 and taken into the microcomputer 19. The microcomputer 19 determines whether the captured measured value is larger than α. If this measured value is smaller than α, it means that the origin hole 30 is not included in the optical path 16. If the measured value is smaller than α, the microcomputer 19
sends the drive pulse to the driver 24 and the pulse motor 21
Rotate one step. When the pulse motor 21 rotates one step, the turret 15 rotates one step via the gear 23.

After rotating the turret 15 by one step, the measurement is performed again, and it is checked whether this measured value has become larger than α.

During the step feed of the turret 15, the origin hole 30
When α enters the optical path 16, the measured value becomes larger than α, so the step feed of the turret 15 is stopped at this point. In this case, the reference position A in FIG. 3 is detected by the photodetector 14.

The number of steps for inserting each of the filters 27 to 29 into the optical path 16 with this reference position A as the origin is as follows.

Filter 27...24 steps Filter 28...72 step filter 29...120 steps This number of steps is predetermined and stored in the ROM of the microcomputer 19.

Therefore, when the reference position A is detected, the number of steps of the selected filter is read from the ROM. For example, if filter 27 is selected, the number of steps is "24".
is read out, and the microcomputer 19 generates a corresponding drive pulse using software. This drive pulse is sent to the driver 24 and drives the pulse motor 21 to 24.
The filter 27 is inserted into the optical path 16 by rotating it by a step. If the filter 29 is selected, the pulse motor 21 rotates 120 steps to insert the filter 29 into the optical path 16.

FIG. 5 shows an embodiment in which the origin hole is detected from the number of steps in the light transmission section. In the same manner as in FIG. 4, the measured values are checked while the turret 15 is being moved step by step. If this measured value is smaller than β, a part of the turret 15 is in the optical path 16. When the measured value becomes larger than β during step feeding of the turret 15, the origin hole 30. This is when any of the filters 27 to 29 enters the optical path 16. From the time when this measured value becomes larger than β, the microcomputer 19 moves the turret 15 further in steps while counting the number of drive pulses. Then, when the measured value becomes smaller than β, the step feed of the turret 15 is stopped. When this step feeding is stopped, the number of driving pulses counted is checked. The number of steps of the origin hole 30 is "6", but if the number of drive pulses is "3 to 7" considering measurement errors etc., it is determined that the origin hole 30 is the origin hole 30. Furthermore, if the number of driving pulses is 3 to 7 or more, it is one of the filters 27 to 29, so step feed is started again and the measured value is lower than β according to the procedure described above. A large section is detected and its drive pulse is examined to determine whether the origin hole is 3 degrees or not.

When the origin hole 30 is detected, the reference position B is in the optical path 16, so the number of steps to insert each filter 27 to 29 into the optical path IM with this reference position B as the origin is as follows. It is as follows.

Filters 27...21 steps Filters 28...69 Step filters 29...117 steps Then, this step number is read out from the ROM, the pulse motor 21 is rotated, and a desired filter is inserted into the optical path 16.

After switching the filter using these steps,
Measure chemical analysis slide 1. First, the gain of the amplifier 17 is set according to the selected filter, for example, the filter 27. Next, the push lever 6 is operated to position the chemical analysis slide 1 at the measurement position. The reflected light from this measurement element 2 is transmitted through a lens 13 and a selected filter 2.
After passing through 7, the light enters the photodetector 4, and only the light in the wavelength range selected by the filter 27 is photoelectrically converted. The output signal of this photodetector 14 is amplified by an amplifier 17, and then
The A/D converter 18 converts it into a digital signal, and this digital signal is taken into the microcomputer 19.

When the measurement of the chemical analysis slide 1 is completed, the push lever 6 moves forward to receive the slide and discharge it to the IL 7. While the pushing lever 6 is moving forward, the reflection density of the white portion 6a is measured. After this measurement, the push-in lever 6 is moved back and measurement is performed again in this state. When the push-in lever 6 is in the retracted state, a black-painted cover (not shown in Figure 1) is located directly above the measurement position, so the reflection density of this cover is measured and used as the black reference density. Using these white and black reflection densities as reference values, the measured values of the chemical analysis slide 1 are corrected to calculate correct reflection densities. Since the microcomputer 19 stores in its memory a calibration curve showing the relationship between optical density and substance concentration, it refers to this calibration curve and outputs the substance concentration.

In addition, in the above example, the measurement system is a reflective type, but
The present invention can also be used for transmission type devices.

〔Effect of the invention〕

The present invention provides a turret equipped with a plurality of filters.
By forming an origin hole with a smaller diameter than this and measuring the output of the measurement system while stepping the turret, it is possible to detect that the origin hole has entered the optical path 16, and determine which position is the reference position. As a result, the turret is rotated by the number of steps required to insert the desired filter into the optical path, so the origin hole detection sensor used conventionally is no longer necessary. Therefore, the structure can be simplified, the cost can be reduced, and the device can be downsized by the space required to install the sensor.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a chemical analysis apparatus implementing the present invention. i'Im is a plan view of the turret. FIG. 3 is a graph showing the number of steps of the turret and the output of the photodetector. FIG. 4 is a flowchart showing a procedure for detecting a reference position from the measured values of the measurement system and switching the filter. FIG. 5 is a flowchart showing the procedure for detecting a reference position from the size of the origin hole and switching the filter. 1...Chemical analysis slide 2...Measuring element 6...Push lever 6a...White part 4...Photodetector 15...Turret 21...Pulse motors 27 to 29...Filter. Figure 4

Claims (3)

[Claims] (1) A turret driven by a pulse motor is placed on the optical path of the measurement system including the photodetector, and multiple filters are placed concentrically on this turret, and an origin hole with a smaller diameter than these filters is installed. The turret position when the measurement system detects this origin hole is used as a reference position, and the number of steps of the turret required to insert each filter into the optical path of the measurement system from this reference position is determined in advance. While stepping the turret when switching the filter, check the output of the measurement system to detect the reference position,
A filter switching method characterized in that after this reference position is detected, the turret is rotated by a predetermined number of steps to insert a desired filter into the optical path. (2) Check the output when measuring the filter that gives the maximum output of the measurement system and the origin hole, set the reference output so that it falls between these outputs, and adjust the rotation of the turret. 2. The filter switching method according to claim 1, wherein the reference position is detected at the point in time when the output of the measurement system reaches the reference output. (3) While the turret was rotating, the number of steps in the light transmission section where the output of the measurement system exceeded a certain level was measured, and the reference position was detected when this number of steps matched the number of steps in the origin hole. A filter switching method according to claim 1, characterized in that: