JPH0365846B2 - - Google Patents

Description

[Detailed Description of the Invention] In recent years, it has been known that in processing processes such as metal casting, rolling, and annealing, temperature control during processing greatly affects the quality of the product. Automatic temperature control has come to be performed based on the measured values.

Optical thermometers such as color thermometers and brightness thermometers, which can be measured non-contact, are used as a means of measuring temperature, but the optimum temperature for metal processing is only at a certain temperature. Since the allowable error range is extremely narrow, the conditions that must be met for an optical thermometer used for such temperature control are that the measurable temperature range is relatively narrow and the measurable temperature range is It must have good accuracy within the temperature range, and it must not change over time.

Therefore, the present invention has been devised to obtain a color thermometer that can satisfy such conditions.Examples will now be described in detail with reference to the drawings.

As shown in FIG. 1, a light beam 3 radiated from a temperature-measuring object 1 such as a metal lump or a metal plate is transferred to a light receiving lens 5, an optical path switch 6 consisting of a rotary reflector, and two types having different passing wavelengths. A measuring optical system that makes the light ray 4 enter the photoelectric conversion element 7 through a rotary filter 10 having filters 11 and 12, and a standard light source 2 consisting of a light bulb lit with a constant current is passed through an optical path switch 6, It is equipped with a calibration optical system that causes the light to enter the photoelectric conversion element 7 through the rotary filter 10.

This rotary filter 10 is rotated by a motor 8, and a two-phase alternating current generator 9 is connected to the motor 8 in addition to the rotary filter 10.

Furthermore, an amplifier 13 that amplifies the electrical output of the photoelectric conversion element (7), and two outputs A, which correspond to the intensities of the wavelength components of the light beams that have passed through two types of filters 11 and 12, convert the output of this amplifier 13 into two outputs A, A separator 14 that separates the two outputs A and B into DC components, and smoothing circuits 15 and 1 that smooth the two separated outputs A and B into DC components, respectively.
6, and first and second D/A conversion circuits 17, 1, each of which has an output connected to a reference voltage terminal ref, and further has a digital input terminal.
8, and first and second up/down counters 19, 20 connected to respective digital input terminals of these two D/A conversion circuits 17, 18.

Furthermore, the first and second D/A conversion circuits 1
a subtraction amplifier 21 that subtracts each analog output of 7 and 18 and amplifies it; a comparison circuit 22 that compares the output of this subtraction amplifier 21 with a ground potential and generates a positive or negative output; and a subtraction amplifier 21 It is equipped with an absolute value amplifier 23 that amplifies the absolute value of the output of , and a pulse generator 24 driven by the output of this absolute value amplifier 23, and the output of the comparator 22 is
It is connected to the up or down counting direction input terminal of each counter 19, 20, and the output of the pulse generator 24 is connected to the counting input terminal Q of each counter 19, 20.

The first counter 19 has an enable terminal e to which a voltage is applied when the optical path switch 6 is in the calibration operation position shown by the dotted line, and the second counter 20 has an enable terminal e that is connected to the optical path switch 6. When the counter 20 is in the temperature measurement operation position shown by the solid line, there is an enable terminal e to which a voltage is applied, a preset data input terminal S for setting the count value of this counter 20 to a constant value in advance, and a voltage input terminal S during the preset operation. It has a preset terminal P to which is applied. and,
A thumb switch 25 is provided for applying predetermined data to the preset data input terminal S.

The count output of the second counter 20 is the count output of the second D/
In addition to the A conversion circuit 18, it is led to an address terminal of a ROM 26, and the output terminal of the ROM 26 is led to an indicator 27.

Next, the operation of the color thermometer of the present invention configured as described above will be explained.

When the light beam 3 or 4 radiated from the temperature measurement object 1 or the standard light source 2 is incident on the photoelectric conversion element 7 through the rotating filter 10, the intensity of the light beam from the photoelectric conversion element 7 corresponds to the intensity of the light beam that has passed through the rotating filter 10. This generates an electrical output that is amplified by the amplifier 13 to obtain an output with the waveform shown in FIG. When separated into two outputs (A, B in Fig. 2) with peak values a and b corresponding to the intensity of the wavelength components that have passed through 11 and 12, and smoothed by smoothing circuits 15 and 16, the output is proportional to the peak values a and b. DC voltages a' and b' can be obtained, and the DC voltages a' and b' can be obtained from the first and second D/A conversion circuits 17 and 18, respectively.
is applied to the reference voltage terminal ref.

As is well known, a color thermometer determines the color temperature by the ratio of the intensity of two different wavelength components contained in the light beam 3 radiated from the object 1 to be measured. By obtaining the ratio a'/b' of the output voltages a' and b' of the smoothing circuits 15 and 16, the color temperature can be determined.

Therefore, prior to the temperature measurement operation, a calibration operation is performed.The optical path switch 6 is switched to the position shown by the dotted line, and the light beam incident from the object to be measured 1 is
, and the light ray 4 radiated from the standard light source 2,
An optical path is formed so that the light passes through the rotary filter 10 and enters the photoelectric conversion element 7, and the interlocked changeover switches 28 and 29 are switched as shown by dotted lines to supply a constant current to the standard light source 2 to determine the measurable temperature range. Lights up at the center temperature of, for example, 1000℃.

At this time, set the count value corresponding to the count value of 1000℃ on the thumb switch 25, and set the count value corresponding to the count value of 1000℃.
_D1 is applied to the preset data input terminal S of the second counter 20, a voltage is applied to the preset terminal P to preset the second counter 20, and a voltage is applied to the enable terminal e of the first counter 19. is applied to enable the first counter 19 to perform a counting operation.

Reference voltage terminal ref of second D/A conversion circuit 18
Since the voltage b' from the second smoothing circuit 16 is applied to and the preset count value _D1 is applied to the digital input terminal, the second D/A conversion circuit 18 applies the voltage b'. ′, D ₁ is generated.

On the other hand, the voltage a' from the first smoothing circuit 15 is applied to the reference voltage terminal ref of the first D/A conversion circuit 17, and the count value D ₂ of the first counter 19 is applied to the digital input terminal. is applied, so the first
The D/A conversion circuit 17 generates an analog voltage a'·D ₂ .

Since the differential voltage a'·D ₂ to b'·D ₁ between the outputs of each D/A converter circuit 17 and 18 is obtained from the subtracting amplifier 21, unless this differential voltage is zero, the absolute value amplifier 23 outputs the differential voltage. The pulse generator 24 is driven to apply a pulse voltage to both counters 19 and 20, and the comparator 22 compares the difference voltage with the ground potential, and the voltage related to the positive and negative polarities of the difference voltage is applied to both counters 19 and 20.
20 up or down counting direction input terminals.

At this time, since the enable voltage is applied only to the first counter 19, the first counter 1
Only number 9 can perform counting operation, and it stabilizes by performing counting operation until the output of subtracting amplifier 21 becomes zero, but the counted value D ₄ at this stable time is a′・D ₄ = b′D ₁ , D ₄ =b'/a'D ₁ , which is set in the first counter 19.

In this way, the count values of both counters 19 and 20 are set in a relationship corresponding to 1000°C by the light beam 4 radiated from the standard light source 2 which is turned on at 1000°C.

Next, the optical path switch 6 is switched to the temperature measurement position shown by the solid line, and the light beam 3 radiated from the temperature measurement object 1 is
When an optical path is formed so that the light enters the photoelectric conversion element 7 through the rotary filter 10, and the interlocked changeover switches 28 and 29 are switched as shown by the solid line, the first counter 19 changes to the previously set count value. _D4 is held, the second counter 20 is released from its preset state, and a voltage is applied to its enable terminal e to enable counting.

At this time, the voltage from the first smoothing circuit 15 is applied to the reference voltage terminal ref of the first D/A conversion circuit 17.
a'' is applied, and the count value _D4 set before the first counter 19 is applied to the digital input terminal, so the first D/A conversion circuit
Generates an analog voltage of a″・D ₄ .

On the other hand, the voltage b'' from the second smoothing circuit 16 is applied to the reference voltage terminal ref of the second D/A conversion circuit 18, and the count value D ₃ of the second counter 20 is applied to the digital input terminal. is applied, so the second
The D/A conversion circuit 18 generates an analog voltage b″·D ₃ .

Since the difference voltage a″·D ₄ to b′·D ₃ between the outputs of each D/A conversion circuit 17 and 18 is obtained from the subtraction amplifier 21, unless this difference voltage is zero, the difference voltage is obtained by the absolute value amplifier 23. The pulse generator 24 is driven to apply a pulse voltage to both counters 19 and 20, and the comparator 22 compares the difference voltage with the ground potential, and the voltage related to the positive and negative polarities of the difference voltage is applied to both counters 19 and 20.
20 up or down counting direction input terminals.

At this time, since the enable voltage is applied only to the second counter 20, the second counter 20
Only 0 can perform the counting operation, and the output of the subtracting amplifier 21 performs the counting operation until it becomes zero and becomes stable, but the counted value D ₃ at this stable time is a″・D ₄ =b″・From D ₃ , D ₃ =a″/b″D ₄ , which is set in the second counter 20.

In this way, the count value D ₃ of the second counter 20 when stable is the color temperature of the object to be measured 1 obtained based on the count value D ₄ of the first counter 19 calibrated with the standard light source 2. It corresponds to

The ROM 26 to which the output of the second counter 20 is applied to the address terminal stores a correspondence table between the count value D ₄ and color temperature, so that the count value D ₄
By addressing the color temperature, output the color temperature.
This is indicated by the indicator 27.

As explained above, according to the color thermometer of the present invention, temperature measurement operation can be started after calibration. Even if a drift occurs due to temperature, the color temperature instruction is not affected, and an accurate color temperature can be specified.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the color thermometer of the present invention, and FIG. 2 is a waveform diagram used to explain the operation of the color thermometer shown in FIG. DESCRIPTION OF SYMBOLS 1...Temperature measurement object, 2...Standard light source for calibration, 6...Optical path switch, 7...Photoelectric conversion element, 8...Motor, 9...
2-phase alternator, 10... rotary filter, 11, 1
2... Two types of filters, 14... Separator, 15, 1
6... Smoothing circuit, 17, 18... D/A conversion circuit, 1
9, 20... Up/down counter, 21... Subtraction amplifier, 22... Comparator, 23... Absolute value amplifier,
24...Pulse generator, 25...Thumb switch, 2
6...ROM, 27...indicator.

Claims (1)

[Scope of Claims] 1. An optical system that causes one of the light rays radiated from a standard light source for calibration or a temperature measurement object to enter a photoelectric conversion element through two types of filters having different passing wavelengths; first and second D/A conversion circuits each applying two outputs corresponding to the intensities of the light beams that have passed through the two types of filters to reference voltage terminals; and the first and second D/A conversion circuits. While there is a difference between the first and second counters that apply count values to digital input terminals of the circuit, and the analog outputs of the first and second D/A conversion circuits, the first and second counters apply count values to digital input terminals of the circuit; A circuit that applies a pulse voltage to zero the above difference, and operates only one of the two counters according to the calibration operation or temperature measurement operation,
In the temperature measurement operation, the first and second D/A
A color thermometer comprising: means for zeroing out the difference in analog output of a conversion circuit; and means for indicating a count value of a counter operated during a temperature measurement operation in correspondence with color temperature.