Synchronization signal detection unit and temperature measurement device using the same

Abstract

To provide a synchronization signal detection unit capable of detecting synchronization signals without providing synchronization signal forming marks on a rotating plate having filter regions and a temperature measurement device using the same.SOLUTION: A synchronization signal detection unit comprises: a first filter and a second filter having mutually-different spectral transmission characteristics, provided in one or more sets in a circumferential direction; a light source disposed on one side of a rotating plate without synchronization signal forming marks and a light-receiving sensor disposed on the other side of the rotating plate; and a third filter having the same spectral transmission characteristic as the first filter or the second filter, provided in an optical path from the light source to the light-receiving sensor, or in the light-receiving sensor itself or in the light source itself. A synchronization signal in the rotating plate is detected on the basis of the comparison between a first output of the light-receiving sensor through the first filter and the third filter and a second output of the light-receiving sensor through the second filter and the third filter.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention provides a rotating plate having a filter region including at least one pair of a first filter and a second filter having different spectral transmission characteristics arranged in a circumferential direction, and having no marks for forming synchronization signals, wherein: The present invention relates to a synchronization signal detection unit capable of detecting a synchronization signal and a temperature measurement device using the same. [Background technology]

[0002] Known temperature measurement devices use the two-color temperature method, which converts temperature from the ratio of radiance using two different wavelengths that are close to each other. Among various specific methods using the two-color temperature method, one is known that measures temperature at low cost by providing a first filter and a second filter with different spectral transmittance characteristics in the filter area of ​​a rotating plate in the optical path from the measurement object to the sensor (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 61-011368 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, the rotating plate is provided with a plurality of filter regions and a synchronization signal forming mark. Specifically, the edges of the transmission windows in the circumferential direction of the rotating plate are considered to correspond to the synchronization signal forming mark. When the synchronization signal forming mark is provided on the rotating plate in this way, the filter region other than the synchronization signal forming mark inevitably becomes narrower, which is an inconvenience.

[0005] An object of the present invention is to provide a synchronization signal detection unit capable of detecting a synchronization signal without providing a mark for forming a synchronization signal on a rotating plate having a filter region, and a temperature measuring device using the same. [Means for solving the problem]

[0006] The synchronization signal detection unit of the present invention is a synchronization signal detection unit for a rotating plate that has a filter area that includes one or more pairs of a first filter and a second filter with different spectral transmittance characteristics arranged circumferentially, but does not have a mark for forming a synchronization signal, and has a light source provided on one side of the filter area on the rotating plate, a light receiving sensor provided on the other side, and a third filter that is provided in the optical path from the light source to the light receiving sensor, or is provided on the light receiving sensor itself or the light source itself, and has the same spectral transmittance characteristics as the first filter or the second filter, and is characterized in that it detects the synchronization signal on the rotating plate based on a comparison between a first output at the light receiving sensor via the first filter and the third filter and a second output at the light receiving sensor via the second filter and the third filter.

[0007] Furthermore, the temperature measuring device according to the present invention is characterized by comprising the above-mentioned synchronization signal detection unit, the rotating plate, a second light receiving sensor for receiving light emitted from the object to be measured and measuring the temperature of the object to be measured, and a light guiding means for guiding the first light from the object to the second light receiving sensor via the rotating plate through the first filter and the second light through the second filter in a time series manner. [Effects of the Invention]

[0008] According to the present invention, the rotating plate having the filter area does not have a mark for forming a synchronization signal, so that the filter area can be made wider. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating the overall configuration of a temperature measuring device using a synchronization signal detection unit according to an embodiment of the present invention. [Figure 2]1 is a block diagram of a temperature measurement device using a synchronization signal detection unit according to an embodiment of the present invention. [Figure 3] 1A and 1B are diagrams showing the configuration of a rotary plate equipped with different filters according to an embodiment of the present invention, in which (a) shows a two-wavelength, four-division configuration, and (b) shows a two-wavelength, 20-division configuration. [Figure 4] 10 is an explanatory diagram of a synchronization signal detection unit according to an embodiment of the present invention in which a rotating plate does not have a mark for forming a synchronization signal. FIG. [Figure 5] FIG. 10 is a diagram illustrating an output of a trigger sensor according to an embodiment of the present invention. [Figure 6] 5A to 5C are explanatory diagrams of image addition processing and averaging processing of the image addition processing in the temperature measuring device according to the embodiment of the present invention. [Figure 7] FIG. 10 is an explanatory diagram of a comparative example in which a rotating plate has a mark for forming a synchronization signal. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0011] (First embodiment) Prior to a specific description of this embodiment, the two-color thermometry method will be described first.

[0012] (Two-color thermometry) The concept of two-color thermometry is explained below. To measure the temperature of high-temperature workpieces above 300°C without contact, the electromagnetic radiation emitted by the object is measured and the temperature is calculated from its intensity. This method is commercially available as a radiation thermometer, which obtains temperature from visible or infrared light, or as a thermograph, which measures temperature distribution. The object is generally a non-blackbody, and to obtain the true temperature from a radiation thermometer or a thermograph, correction must be made for the emissivity, which is the ratio of the amount of radiation to that of a blackbody. However, the emissivity of a non-blackbody generally varies depending on its material, shape, and temperature, making it difficult to obtain an accurate temperature.

[0013] Therefore, two-color thermometry is used. Two-color thermometry focuses on the fact that the emissivity of radiation at two closely spaced wavelengths is the same, and since the ratio of the radiation amounts at the two wavelengths is functionally related to the true temperature, the radiation amounts at the two wavelengths are measured to calculate the true temperature. This can be explained using the following formula:

[0014] The Wien radiation formula for the amount of radiation Mλ at wavelength λ is:

[0015]

number

[0016] where c1: First radiation constant = 2πc2h = 3.741844 x 10-16 [Wm2] λ: Wavelength μm c2: Second radiation constant = 1.438769X10-2[m K] T: Absolute temperature (Kelvin) Let the two wavelengths to be measured, λ1 and λ2, their emissivities, ε1 and ε2, and the radiation amounts of both, M1 and M2, respectively. Let R be the ratio of the radiation amounts at both wavelengths (output ratio at the image sensor). R can be expressed by equation (2).

[0017]

number

[0018] When the condition ε1=ε2 is met, equation (2) becomes equation (3).

[0019]

number

[0020] By rearranging both sides, the temperature T can be obtained by equation (4).

[0021]

number

[0022] Here, C3 and C4 are constants calculated from both wavelengths and are expressed by the following formula.

[0023]

number

[0024] Even if the emissivity at two wavelengths or the transmittance of an inclusion differs, if the ratio does not change with temperature, the true temperature of an object whose temperature changes can be determined by correcting the ratio with a black body.

[0025] (Rotating filter type temperature measurement) Figure 1 shows the overall configuration of a temperature measurement device according to an embodiment of the present invention, which is composed of a measurement head and a computer. The measurement head includes an objective lens 1, a rotary filter 2, an image sensor unit 3, a wavelength-specific image distribution circuit 4, an image addition / non-addition processing circuit 5, a memory bank 6, a trigger light source 8, a trigger sensor 9, and a motor 10 for rotating the rotary filter 2 at a constant speed. A computer 7, which performs at least exposure time instruction and two-color temperature processing, is equipped with computer hardware and software. The image sensor unit 3 includes an image sensor 3a (a second light-receiving sensor separate from the trigger sensor 9), an analog amplifier 3b, and an A / D conversion element 3c.

[0026] These components are numbered the same as in the block diagram of FIG.

[0027] In this embodiment, in order to reduce costs, a rotary filter 2 is provided as a rotary plate between the objective lens 1 and the image sensor 3a. The rotary filter 2 functions as a bandpass filter and includes a first filter region and a second filter region adjacent to each other in the rotational direction, through which a first light and a second light having different wavelengths pass, respectively, and multiple sets of these filter regions are provided in the rotational direction.

[0028] In Fig. 3(a), the filter is divided into four parts, with two sets of a first filter 12 and a second filter 13. In Fig. 3(b), the filter is divided into 20 parts, with ten sets of a first filter 22 and a second filter 23.

[0029] While conventional two-color thermometers measure one point or one area in one dimension, this embodiment uses an image sensor and measures a large number of points, such as 300,000 points (640x480).

[0030] Furthermore, while conventional two-color thermometers rely on analog signal processing with floating elements to measure temperature from the radiation ratio of two wavelengths, this embodiment is able to perform accurate numerical processing based on Wien's radiation law to calculate the temperature of each of the approximately 300,000 pixels.

[0031] In this embodiment, the image sensor 3a is a single image sensor with two-dimensional pixels and a global shutter in which each pixel is simultaneously exposed to light and outputs a digital signal. The global shutter method is adopted because, when performing dynamic imaging with the rotary filter 2 interposed, it is preferable that each pixel be simultaneously exposed to light and output a digital signal.

[0032] The objective lens 1 captures an image of the object to be measured on the image sensor 3a through a bandpass filter configured on the rotating plate of the rotary filter 2. In this way, the objective lens 1 functions as a light guiding means that guides the first light and second light from the object to the image sensor 3a in a time-series manner via the rotary filter 2. As the light guiding means, a glass fiber image guide tube is provided on the focal plane of the objective lens, and a lens is placed at the end of the image guide fiber, which transmits the light to the image sensor through the rotating filter plate. This makes it possible to perform temperature measurement while avoiding stray light from around the object to be measured.

[0033] Here, prior to temperature measurement, the computer 7 instructs the image sensor unit 3 to set an exposure time, and the image sensor 3a can set the exposure time using the global shutter function.

[0034] In the image sensor unit 3, the output of each pixel of the image sensor 3a is amplified by the analog amplifier 3b, and then sent as 12- to 16-bit digital data by the A / D converter 3c to the wavelength-specific image distribution circuit 4. The images are then stored in each wavelength region of the memory bank 6 as images of wavelengths identified by the trigger signal, which is the output of the trigger light-receiving sensor 9 (Fig. 2).

[0035] Regarding data reading, the image adding / non-adding processing circuit 5 reads the required two pairs of wavelength data from the memory bank 6, and after adding or non-adding the data for each pixel according to a command from the computer 7, outputs it to the computer 7. The computer 7 then performs two-color temperature processing on the non-added or added image data, and then outputs a signal for display or control.

[0036] Regarding image addition in the image addition / non-addition processing circuit 5, which serves as an output addition unit, when the required exposure time is longer than 1 / (P × Q) seconds, two pairs of memory values ​​read from the memory bank 6 are added together (Figure 7), where P revolutions per second (RPS) is the rotation speed of the rotary plate of the rotary filter 2 and Q is the number of filter divisions. For example, if the rotation speed of the rotary plate of the rotary filter 2 is 2400 RPM (40 revolutions per second) and the number of filter divisions is 4 (the rotary plate is divided into four), the exposure time per wavelength is 1 / 40 × 1 / 4 × 1000 = 6.25 milliseconds (ms), but by adding two images for each wavelength, the exposure time per wavelength can be extended to 12.5 milliseconds (ms).

[0037] In this embodiment, when the object to be measured is on the low temperature side (for example, below 500°C), the amount of light emitted from the object to be measured is small, so that the amount of exposure to the image sensor is increased by rotating a rotating plate with a small number of filter divisions at a slower speed, and further by performing the image addition process shown in Figure 6, the sensor output can be increased using the output of the output addition unit.

[0038] On the other hand, if the measurement target is on the high temperature side (for example, 500°C or higher), the rotating plate with a large number of filter divisions is rotated at high speed. Then, by performing the averaging process of image addition shown in Figure 6, the accuracy of temperature measurement can be improved by using the averaging of the output of the output adder.

[0039] (Sync signal detection) In the rotary filter 2 as a rotating plate, a synchronization signal with the filter position is required so that the image sensor can capture an image when the filter area that transmits a predetermined wavelength is in front of the image sensor.

[0040] 1 and 4, in this embodiment, a trigger light source 8 is provided as a light source on one side of the filter region on the rotating plate, and a trigger light receiving sensor (photodiode) 9 is provided as a light receiving sensor on the other side. The synchronization signal is detected by comparing the outputs when light from the trigger light source 8 is received by the trigger light receiving sensor (photodiode) 9 via the trigger filter 50 (FIG. 4).

[0041] That is, the trigger filter 50, which has the same spectral transmittance characteristics as the first or second filter, is the same filter (same spectral transmittance characteristics) as one of the different filters on the rotating plate as the third filter, so when the filter on the optical path of the rotating plate is the same as the trigger filter 50, the output of the trigger light-receiving sensor 9 is turned on. On the other hand, when the filter on the optical path of the rotating filter 2 is different from the trigger filter 50, the output of the trigger light-receiving sensor 9 is turned off.

[0042] That is, a synchronization signal on the rotating plate is detected based on a comparison between a first output of the light receiving sensor via the first filter and the third filter and a second output of the light receiving sensor via the second filter and the third filter.

[0043] Such a trigger filter 50 is provided as a third filter, separate from the first and second filters, in the optical path from the trigger light source 8 to the trigger light-receiving sensor 9. Alternatively, the trigger filter 50 may be provided on the trigger light-receiving sensor itself or the trigger light source itself, or the trigger filter 50 may be attached to the trigger light-receiving sensor 9 or the trigger light source 8 and integrated with them.

[0044] In this embodiment, the synchronization signal can be detected in this manner, and the image signals can be sorted by wavelength by the wavelength-specific image distribution circuit 4 and stored in a predetermined memory area of ​​the memory bank 6 (FIG. 2).

[0045] In this embodiment, regardless of the number of divisions (even if the number of filter divisions is increased), there is no need to assign a trigger detection area to the rotary filter 2, and a wide filter area can be used (Figures 3(a) and (b)).

[0046] In other words, since there are no synchronization signal forming marks in either the circumferential or radial direction of the rotating plate, a wide filter area can be provided.Incidentally, in the comparative example shown in Figure 7, since synchronization signal forming marks 16 to 19 are provided in the radial direction of the rotating plate, a wide filter area cannot be provided in the radial direction of the rotating plate.

[0047] 7, 14b is an image sensor, 32 is a first filter, 33 is a second filter, and two sets of the first filter 32 and the second filter 33 are provided. A light source and a sensor for reading the synchronization signal formation marks 16 to 19 are provided on either side of the rotating plate of the rotary filter, and the trigger light source 8 and the trigger detection sensor 9 in FIG. 4 are used with the trigger filter 50 removed.

[0048] In this manner, in this embodiment, by widening the filter area, the output of the image sensor can be increased, enabling highly accurate temperature measurement.

[0049] The output of the trigger detection sensor in this embodiment is shown in Fig. 5. Image sensor 14a transitions from an output state in which light of the first wavelength λ1 is received (ON) and light of the second wavelength λ2 is not received (OFF) to an output state in which light of the first wavelength λ1 is not received (OFF) and light of the second wavelength λ2 is received (ON).

[0050] In this embodiment, the above-mentioned synchronization signal (trigger signal) is obtained, and the image signals are sorted by wavelength using the signal and stored in a predetermined memory area (memory bank 6) shown in FIG. Light of wavelength λ1 that passes through the filter is stored in memory areas 1-1, 1-2, ... 1-n in sequence as the rotary filter 2 rotates. Also, light of wavelength λ2 that passes through the λ2 filter is stored in memory areas 2-1, 2-2, ... 2-n in sequence as the rotary filter 2 rotates.

[0051] (Variation) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

[0052] For example, in the above-described embodiment, the rotating plate is provided with two or more sets of a first filter and a second filter arranged in the circumferential direction, but it may also be provided with one set of a first filter and a second filter arranged in the circumferential direction.

[0053] Furthermore, in the above-described embodiment, an image sensor with two-dimensional pixels is used as the temperature measurement device, but it is also possible to measure the temperature of the object to be measured using a line sensor with one-dimensional pixels, a photodiode arranged in a dotted pattern, or the like. [Explanation of symbols]

[0054] 1 Objective lens, 2 Rotating filter, 3 Image sensor unit, 3a Image sensor, 3b Analog amplifier, 3c A / D conversion element, 4 Wavelength-specific image distribution circuit, 5 Image summation / non-summation processing circuit, 6 Memory bank, 7 Computer, 8 Trigger light source, 9 Trigger light receiving sensor, 10 Motor, 41 Measurement head

Claims

1. A synchronization signal detection unit for a rotating plate having one or more pairs of a first filter and a second filter having different spectral transmission characteristics arranged in a circumferential direction as a filter region, and not having a synchronization signal forming mark, a light source provided on one side of the rotary plate across the filter area; a light receiving sensor provided on the other side; a third filter that is provided in an optical path from the light source to the light-receiving sensor, or that is provided in the light-receiving sensor itself or the light source itself, and that has the same spectral transmittance characteristics as the first filter or the second filter; and A synchronization signal detection unit characterized by detecting a synchronization signal on the rotating plate based on a comparison between a first output of the light receiving sensor that has passed through the first filter and the third filter and a second output of the light receiving sensor that has passed through the second filter and the third filter.

2. 2. The synchronization signal detection unit according to claim 1, wherein the third filter is attached to the light receiving sensor itself or the light source itself.

3. a synchronization signal detection unit according to claim 1; The rotating plate; a second light-receiving sensor for receiving light emitted from the measurement object and measuring the temperature of the measurement object; a light guiding means for guiding the first light from the measurement object through the first filter and the second light through the second filter to the second light receiving sensor via the rotating plate in a time-series manner; A temperature measuring device comprising:

4. 4. The temperature measuring device according to claim 3, wherein the second light receiving sensor is an image sensor.

5. The optical system includes two or more sets of the first filter and the second filter in a circumferential direction, and has an output adder that adds outputs of the first light passing through the plurality of first filters in units of each pixel, and adds outputs of the second light passing through the plurality of second filters in units of each pixel, 5. The temperature measuring device according to claim 4, wherein the temperature of the object to be measured is measured based on the output of the output adder or an average of the outputs of the output adder.

6. 6. The temperature measuring device according to claim 3, wherein the light guiding means is an objective lens.

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