JP2010107338A - Mirror surface cooling type dew point meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mirror surface cooling type dew point meter for measuring a dew point of a gas to be measured based on a condensing state on the mirror surface whose temperature is adjusted, capable of improving measurement accuracy of the dew point of the gas to be measured, and measuring the dew point of the gas to be measured in a short time. <P>SOLUTION: This dew point meter includes: a measuring chamber 2 for circulating the gas to be measured inside by supplying/discharging the gas G to be measured; a mirror 3 stored and installed inside the measuring chamber, to be exposed to the circulating gas to be measured; a temperature adjusting means 4 for adjusting the temperature of the mirror; a temperature measuring means 5 for measuring the temperature of the mirror; a light source 9 for illuminating the mirror surface; an imaging camera 10 for imaging the mirror surface; an image analysis means 101 for determining a condensation/frost generation state on the mirror surface based on image information from the imaging camera; and a temperature control means 102 for controlling operation of the temperature adjusting means 4 in order to keep the mirror temperature constant based on a determination result by an image analysis part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention provides a mirror-cooled dew point configured to measure a dew point of a gas to be measured based on a situation in which a mirror is installed inside a measurement chamber through which the gas to be measured flows and condensation occurs on the surface of the mirror whose temperature has been adjusted. It is about the total .

    For example, a dew point meter that can accurately measure the dew point of gas is used for humidity control in clean rooms, dry rooms, etc. in the industrial field where strict humidity control is required, such as semiconductor or battery manufacturing and biotechnology. is needed.

Here, as a dew point meter that can measure the dew point of gas with a small measurement error, a mirror-cooled dew point meter that has traditionally adopted a primary detection method (a method that directly determines the dew point by measuring the temperature of an object) (for example, , See Patent Document 1).

FIG. 10 shows a configuration of a conventional mirror-cooled dew point meter . The mirror-cooled dew point meter A includes a measurement chamber C through which the gas to be measured G is supplied / exhausted and circulates. Inside, a mirror M whose temperature is adjusted by the thermoelectric module E is accommodated and installed.

  The measurement chamber C is provided with a light source La that illuminates the mirror M and a light receiving element Ra that receives reflected light from the mirror M, and further includes a light source Lb that emits reference light, and a light source Lb from the light source Lb. A light receiving element Rb that directly receives the reference light is provided.

In the above-described mirror-cooled dew point meter A, the measurement gas G is continuously supplied to the measurement chamber C (continuous sampling), and the surface Ma of the mirror M is exposed to the flowing measurement gas G. The temperature of the mirror M is controlled (cooled) by the thermoelectric module E in order to forcibly condense the moisture in the gas G to be measured on the surface Ma.

  When condensation occurs on the surface Ma of the mirror M, the light emitted from the light source La is diffusely reflected by condensation, and the amount of light received by the light receiving element Ra is reduced, so that the light received from the light source Lb is directly received by the light receiving element Rb. The balance with the reference light is lost.

  Here, the thermoelectric module E is controlled by the temperature adjustment unit J of the controller H based on the result of comparison in the comparison unit I of the controller H of the imbalance between the light amounts received by the light receiving element Ra and the light receiving element Rb. The temperature of the mirror M is controlled so that the amount of condensation on the surface Ma of M is constant.

In this way, the temperature of the mirror M (surface Ma) in a state where the same amount of dew condensation has occurred becomes the dew point temperature of the gas G to be measured, and this temperature is detected by the temperature sensor S installed in the vicinity of the mirror M. The output from the temperature sensor S is displayed numerically by the temperature meter T.
JP 2003-194756 A

As described above, in the conventional mirror-cooled dew point meter A, in the situation where condensation is formed over the entire surface Ma of the mirror M, the light quantity received by the light receiving element Ra and the light receiving element Rb is imbalanced. The dew point temperature of the measurement gas G is detected by determining the occurrence of dew condensation on the surface Ma of the mirror M and adjusting the temperature of the mirror M based on the above-described light quantity imbalance. Yes.

Here, in the conventional mirror-cooled dew point meter described above, the entire surface Ma of the mirror M on which condensation is formed is the object of observation, and is based on an imbalance in the amount of light received by the light receiving element Ra and the light receiving element Rb. Since the dew point temperature of the gas G to be measured is detected, it is difficult to capture the extremely small and small amount of dew condensation on the surface Ma of the mirror M from the amount of light received by the light receiving element Ra and the light receiving element Rb. Therefore, there is a problem that the measurement accuracy of the dew point temperature is not necessarily sufficient.

Further, in the conventional mirror-cooled dew point meter , since the entire surface Ma of the mirror M on which condensation is formed is to be observed, measurement work is started (supply of the gas G to be measured to the measurement chamber C is started). For example, when the diameter of the mirror M is about 10 mm before the condensation is generated on the entire surface Ma of the mirror M, it takes a long time of about 2 hours depending on the moisture content of the gas G to be measured. Therefore, there is an inconvenience that a very long waiting time is required from the start of the measurement operation to the detection of the dew point temperature of the gas G to be measured.

In view of the circumstances the present invention described above, it is possible to improve the dew point measurement accuracy of the gas to be measured, it possible to implement the measurement of the dew point in the gas to be measured in a short time together, cooled mirror dew point meter It is intended to provide.

In order to achieve the above object, a mirror-cooled dew point meter according to the first aspect of the present invention includes a measurement chamber that supplies / discharges a gas to be measured and causes the gas to be measured to flow therein, and is accommodated in the measurement chamber. A mirror that is exposed to a gas to be measured that is installed and circulated; a temperature adjusting means that adjusts the temperature of the mirror; a temperature measuring means that measures the temperature of the mirror; a temperature display means that displays the temperature of the mirror; A light source that illuminates the surface, an imaging camera that captures the surface of the mirror, an image analysis unit that determines the occurrence of condensation / frost formation on the surface of the mirror based on image information from the imaging camera, and the image analysis unit And a temperature control means for controlling the operation of the temperature adjusting means to keep the temperature of the mirror constant based on the result of the determination by the above.

Also, cooled mirror dew point meter relating to the invention of claim 2 is the cooled mirror dew point meter relating to the invention of claim 1, the image analysis means, first photographed image taken in a time series by an imaging camera By comparing the brightness of all pixels (pixels) with the brightness of all pixels (pixels) in the second and subsequent shot images in order, and comparing the absolute values of the brightness differences of the same pixels It is characterized in that the luminance gradation of each photographed image is obtained and the occurrence of condensation is detected based on the change over time of the luminance gradation in each photographed image.

Moreover, chilled mirror dew-point meter according to the invention of claim 3 is the cooled mirror dew point meter according to the invention of claim 1, the image analysis means, by color analysis of the image information from the imaging camera, the mirror It is characterized by identifying condensation and frost generated on the surface.

Moreover, chilled mirror dew-point meter according to the invention of claim 4 is the cooled mirror dew point meter according to the invention of claim 1, it is characterized in that the imaging camera is provided with a long focal length type optical system.

Moreover, chilled mirror dew-point meter according to the invention of claim 5 is the cooled mirror dew point meter according to the invention of claim 1, the imaging camera is characterized in that it comprises an optical system of the microscope type.

According to the mirror- cooled dew point meter relating to the invention of claim 1, an image obtained by photographing the surface of the mirror is analyzed with respect to a conventional mirror-cooled dew point meter that measures the dew point based on the amount of light reflected on the mirror. By doing so, it is possible to improve the measurement accuracy of the dew point in the gas to be measured, and to measure the dew point in the gas to be measured in a short time.

According to the mirror-cooled dew point meter relating to the invention of claim 2, in the image analysis means, the luminance of all the pixels (pixels) in each of the first and second captured images taken in time series is sequentially The dew point measurement accuracy in the measured gas can be improved by comparing and comparing dew condensation based on the change over time in the luminance gradation of each captured image obtained by the absolute value difference method. It becomes possible to measure the dew point in the gas to be measured over time.

According to the mirror-cooled dew point meter relating to the invention of claim 3, the image information from the imaging camera is color-analyzed by the image analysis means, thereby easily identifying the condensation and frost formed on the mirror surface. Thus, when calculating the humidity from the temperature to another parameter, an appropriate saturated vapor pressure based on the dew point or frost point can be selected.

According to the mirror-cooled dew point meter relating to the invention of claim 4, since the imaging camera has a telescopic optical system, for example, the peripheral wall of the measurement chamber is extremely thick for the purpose of pressure resistance, and from the mirror surface to the imaging camera Even when the distance is large, the surface of the mirror can be effectively photographed, and the dew point can be reliably measured.

According to the mirror-cooled dew point meter relating to the invention of claim 5, since the imaging camera is equipped with a microscope optical system, it is possible to take an image effectively even if the surface of the mirror is extremely small. The entire dew point meter can be made compact, and the overall capacity of the dew point meter can be reduced, resulting in a good response to temperature changes during temperature adjustment. Due to the reduction in volume, the sampling amount of the gas to be measured at the time of dew point measurement can be reduced.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments.
FIG. 1 shows a first embodiment of a mirror-cooled dew point meter according to the present invention. This mirror-cooled dew point meter 1 includes a measurement chamber 2, a mirror 3, a thermoelectric module (temperature adjusting means) which will be described in detail later. ) 4, LED (light source) 9, imaging camera 10, controller 100, etc., and these components are housed in a casing (not shown) to be built as a portable device that can be carried freely. Yes.

As shown in FIG. 1, a mirror-cooled dew point meter 1 in this embodiment is equipped with a measurement chamber 2 through which a gas to be measured G is supplied / exhausted, and this measurement chamber 2 is connected to an inlet 2i and a discharge port. The measurement gas G is supplied / discharged as shown by the arrow i and the arrow o through the inlet 2i and the outlet 2o.

  Further, inside the measurement chamber 2 is housed a mirror 3 for condensing / frosting moisture in the gas G to be measured, and this mirror 3 is located above the thermoelectric module 4 as temperature adjusting means. Based on the operation of the thermoelectric module 4, the temperature is adjusted based on the operation of the thermoelectric module 4, and in particular, the surface 3a of the mirror 3 is adjusted to a desired temperature.

  Further, a temperature sensor 5 as temperature measuring means for measuring the temperature of the mirror 3 (specifically, the temperature of the surface 3a) is installed in the vicinity of the mirror 3 in the support 4s. An output from the temperature sensor 5 is numerically displayed as a dew point temperature by a temperature meter 6 as a temperature display means connected to.

  Further, the thermoelectric module 4 in which the mirror 3 and the like are provided on the support 4s described above is fixedly installed on the base plate 7, and the whole is made of rigid foam urethane in a form in which the mirror 3 is exposed from the upper part of the support 4s. It is surrounded by a heat insulating block 8 made of a heat insulating material such as.

  On the other hand, the measurement chamber 2 is provided with a light source 9 such as an LED (light emitting diode) for illuminating the surface 3 a of the mirror 3, and the surface 3 a of the mirror 3 illuminated by the light source 9 is provided. More specifically, an imaging camera 10 is provided for capturing an image of the condensation / frost formation occurring on the surface 3a of the mirror 3 as an image.

  Incidentally, the imaging camera 10 includes a digital video camera, a digital still camera capable of time-lapse photography, and the like because it is necessary to shoot images in time series as will be described later, in addition to being capable of color photography for reasons described later. Further, the imaging camera 10 has a specification that allows the captured image information to be directly input to a processing device such as a personal computer described later.

  The imaging camera 10 is connected to a controller 100 composed of a control PC (personal computer) or the like, and image information from the imaging camera 10 is sent to an image analysis unit (image analysis means) 101 of the controller 100, Based on the analysis result in the image analysis unit 101, a control signal is sent from the temperature control unit (temperature control unit) 102 of the controller 100 to the thermoelectric module (temperature adjustment unit) 4, and the temperature with respect to the mirror 3 (surface 3 a) described above. The adjustment is executed.

Here, the mirror-cooled dew point meter 1 having the above-described configuration is described as follows: “Measured gas based on the situation when a mirror is installed inside the measurement chamber through which the measured gas flows and the surface of the cooled mirror is condensed. Although it is the same as the conventional mirror-cooled dew point meter (see FIG. 10), the image of the dew / frost formation on the surface 3a of the mirror 3 is provided in the measurement chamber 2. It differs greatly from the conventional mirror-cooled dew point meter in that it is determined by taking a picture directly with the camera 10 and observing the taken image (image analysis).

To measure the dew point temperature of the measurement gas G in the above-described mirror-cooled dew point meter 1, first, at the start of measurement (“step 1” in the flowchart shown in FIG. 2), the measurement gas G is measured in the mirror 3. In order to circulate on the surface 3a, the measurement gas G is continuously supplied into the inside of the measurement chamber 2 (continuous sampling) through the inlet 2i and the outlet 2o as indicated by arrows i and o.

  Next, the temperature of the mirror 3 (surface 3a) is controlled by the thermoelectric module 4 so that moisture in the gas G to be measured is forcibly condensed on the surface 3a of the mirror 3 ("step 2" in the flowchart of FIG. 2). ). Specifically, in a state where the measurement gas G is continuously sampled inside the measurement chamber 2, control is performed to gradually decrease the temperature of the mirror 3.

  As described above, in the situation where the temperature control of the mirror 3 is being performed, the surface 3a of the mirror 3 is directly photographed by the imaging camera 10 (“step 3” in the flowchart of FIG. 2). Specifically, interval shooting is executed in a time series every 1/30 sec.

  An image (image information) taken by the imaging camera 10 is sent to the image analysis unit 101 of the controller 100, and the image analysis unit 101 performs image analysis in a manner described in detail later (in the flowchart of FIG. 2). “Step 4”), it is determined whether or not condensation has occurred (“step 5” in the flowchart of FIG. 2).

  After condensation occurs on the surface 3a of the mirror 3, the operation of the thermoelectric module 4 is controlled by the temperature controller 102 of the controller 100 ("step 6" in the flowchart of FIG. 2), and the amount of condensation on the surface 3a of the mirror 3 Is adjusted so that the temperature of the mirror 3 (surface 3a) is constant.

  In this way, the temperature of the mirror 3 (surface 3a) in a state where the same amount of dew condensation is generated becomes the dew point temperature of the gas G to be measured, and this temperature is detected by the temperature sensor 5 installed in the vicinity of the mirror 3. Then, the output from the temperature sensor 5 is numerically displayed as a dew point temperature by the temperature meter 6, and reading this numerical value ends the measurement of the dew point temperature of the gas G to be measured ("step 7" in the flowchart of FIG. 2).

  Hereinafter, a specific image analysis method (absolute value difference method) for determining condensation in the image analysis unit 101 of the controller 100 will be described in detail.

  As described above, in the situation where the temperature control (cooling) of the mirror 3 is being performed, the surface 3a of the mirror 3 is photographed by the imaging camera 10, and an image obtained by photographing the surface 3a of the mirror 3 as shown in FIG. X is composed of a number of pixels (pixels) “Aa” to “Rr” which are numbered in the vertical direction and numbered in the horizontal direction and numbered in the horizontal direction, and arranged in the vertical and horizontal directions.

  Needless to say, the total number of pixels of the image captured by the imaging camera 10 can be arbitrarily set based on the resolution required for the captured image and the processing capability of the image analysis unit 101.

On the other hand, in the situation where the temperature control (cooling) of the mirror 3 is being performed, as described above, the surface 3a of the mirror 3 is interval photographed in time series every 1/30 sec by the imaging camera 10, and the image of the photographing screen is displayed. In the analysis, first, the first photographed image and the second photographed image are compared, and then the first photographed image and the third photographed image are compared. A process (difference process) for comparing the nth photographed image with the image is performed.
Incidentally, the first photographed image that has been interval photographed as described above is referred to as X1, the second photographed image as X2, the... Nth photographed image as Xn.

  In the image analysis, first, the pixels “Aa” to “Rr” of the first photographed image X1 shown in FIG. 4A and the pixels “Aa” to “Rr” shown in FIG. ) Are compared with the respective pixels “Aa” to “Rr” of the second photographed image X2, and the difference in luminance between all the pixels “Aa” to “Rr” is detected.

Here, if the difference in luminance at the same pixel between the first photographed image X1 and the second photographed image X2 is an absolute value Δt,
For example, the absolute value Δt in the pixel “Aa” is
| X1 “Aa” −X2 “Aa” | = Δt “Aa”
The absolute value Δt in the pixel “Rr” is
| X1 "Rr" -X2 "Rr" | = Δt "Rr"
The following relational expression holds.

By detecting Δt (absolute value of luminance difference) in all the pixels “Aa” to “Rr” and decomposing the absolute value Δt of the difference in each pixel “Aa” to “Rr” into 256 gradations, 1 A “histogram (brightness distribution diagram)” of the second photographed image X2 with respect to the first photographed image X1 is created.
Incidentally, a pixel having a luminance difference of “0” (no luminance change) is canceled (ignored).

  Thereafter, similarly, the third and subsequent captured images X3, Xn (nth captured image)... Are sequentially compared with the first captured image X1, and the difference processing is performed. Based on the absolute value Δt of the luminance difference in “Rr”, the “histogram” of each of the compared captured images (the third captured image X3 for the first image, the nth captured image Xn for the first image,...). ".

  Here, as the measurement progresses, condensation occurs on the surface 3a of the mirror 3, and the n-th image shown in FIG. 4B is taken with respect to the first image X1 shown in FIG. 4A. When a water drop (dew) V is photographed on the image Xn, the central pixel “Lc” to which the water drop V has adhered and the peripheral pixels “Kb”, “Kc”, “Kd”, “Lb”, “ The luminances of “Ld”, “Mb”, “Mc”, and “Md” are remarkably increased, and the “histogram” in the n-th photographed image Xn is the “histogram” of the previous photographed image X (n−1). It will change greatly with respect to “histogram”.

  FIG. 6 is a graph in which “average”, “standard deviation”, and “change amount” of each “histogram” created as described above are plotted in time series. It can be seen that the “average”, “standard deviation”, and “change amount” in the histogram are changing greatly.

  As is apparent from the graph of FIG. 6 described above, based on the change over time of the luminance gradation in the “histogram” of the captured images taken in time series, in detail, the above-mentioned luminance gradation has changed greatly, and therefore condensation has occurred. The occurrence of condensation can be detected and the point in time when condensation has occurred can be specified.

  When detecting the occurrence of condensation, for example, if the “average” value of the “histogram” in the photographed image at a certain point in time is greater than or equal to the “average” value of the “histogram” in the previous photographed image. Needless to say, the detection sensitivity can be arbitrarily set, such as “copied that condensation has occurred”.

Further, as a method for detecting the occurrence of condensation, a conventional method is used in which a histogram in which the luminance (saturation) of each pixel is decomposed into 256 gradations detects condensation based on the movement of the average value or peak value over time. It is also possible to employ a detection method similar to that of a mirror-cooled dew point meter .

As described above, according to the mirror-cooled dew point meter 1 having the detailed configuration, by observing the entire surface 3a of the mirror 3 with the imaging camera 10, by detecting dew condensation occurring on a very part of the surface 3a, Compared with the conventional mirror-cooled dew point meter , which measures the dew point in a state where condensation is formed on the entire surface of the mirror, it can capture minute changes related to the occurrence of condensation. It is possible to greatly improve the accuracy related to G dew point measurement.

Further, according to the mirror-cooled dew point meter 1 having the above-described configuration, the surface 3a of the mirror 3 is always observed over the entire surface with the imaging camera 10, and the mirror is detected when it is detected that condensation has occurred on a very small part. Since the dew point temperature of the gas G to be measured can be measured by adjusting the temperature 3, “the dew point is measured in a state where condensation is formed on the entire surface of the mirror ”. Compared to the cooling dew point meter , the dew point of the gas G to be measured can be measured in a short time by controlling the temperature at an early time when the dew condensation starts after the measurement work is started.

Further, according to the mirror-cooled dew point meter 1 configured as described above, by analyzing an image obtained by photographing the surface 3 a of the mirror 3, in detail, the first image photographed in time series by the image analysis unit 101. The luminance gradation of each photographed image obtained by the absolute value difference method with time is sequentially compared between the photographed image X1 and the brightness of all the pixels (pixels) in the second and subsequent photographed images X2, X3. By detecting dew condensation based on the above, it is possible to improve the measurement accuracy of the dew point in the gas G to be measured, and to measure the dew point in the gas G to be measured in a short time.

Furthermore, according to the mirror-cooled dew point meter 1 having the above-described configuration, since the analysis of images taken in time series by the imaging camera 10 is performed in real time, a change in dew amount, in other words, occurrence of dew condensation is 1 It becomes possible to capture with a response of / 30 sec. Therefore, it is possible to eliminate the delay in response at the time of measurement, which has been pointed out as a fatal defect in the conventional specular cooling dew point meter.

By the way, in the conventional mirror-cooled dew point meter (for example, see FIG. 10), it was difficult to deal with contamination on the mirror surface, but in the mirror-cooled dew point meter 1 of the above-described embodiment, the mirror 3 An image analysis unit 101 of the controller 100 takes a first photographed image X1, which is a reference in which no condensation occurs, and the second and subsequent photographed images X2, Xn,. By performing the differentiation process in step S1, it is possible to remove contamination, adhesion of chemical substances, and the like on the surface 3a of the mirror 3 from the image information (data).

  For example, as shown in FIGS. 4 (a) and 5 (a), when a stain W appears in the pixel “Fp” in the first photographed image X1, this stain W is shown in FIG. 4 (a). Although present in the pixel “Fp” of the second photographed image X2 and the n-th photographed image Xn shown in FIG. 5B, as described above, the second and subsequent images with respect to the first photographed image X1. As for the captured images X2, Xn..., Pixels whose luminance difference is “0” are canceled (ignored).

  As described above, the image processing (difference processing) as described above removes noise components of image information caused by dirt, scratches, etc., and prevents erroneous detection, thereby detecting the sensitivity of condensation / frost formation. As a result, the measurement accuracy can be greatly improved.

  As described above, the first photographed image X1 and the second and subsequent photographed images X2, Xn,. Needless to say, the scratches and dirt of the optical system (lens) 10 can be canceled from the image information (data) in the same manner, and the measurement accuracy can be greatly improved.

  In addition, the second and subsequent captured images X2, Xn... With respect to the first captured image X1 as described above are differentiated, and the captured image captured in time series by the imaging camera 10 is always immediately before. It is possible to cancel the contamination (experimental contamination) on the mirror surface caused by contamination of the gas G to be measured supplied during the measurement by performing the difference process on the captured image taken in the measurement. A significant improvement in accuracy can be achieved.

On the other hand, in the above-described mirror-cooled dew point meter 1, in the situation where moisture in the gas to be measured adheres to the surface 3a of the mirror 3, condensation occurs when the temperature of the mirror 3 (surface 3a) is 0 ° C. or higher. If the temperature of the mirror 3 (surface 3a) is 0 ° C. or less, frost is formed.

Here, in the above-described mirror-cooled dew point meter 1, the image analysis unit 101 of the controller 100 performs color analysis on image information (colored captured image) sent from the imaging camera 10, so that the surface 3 a of the mirror 3 is analyzed. It is possible to identify whether condensation has occurred or whether frost has formed.

That is, in the mirror-cooled dew point meter 1 having the above-described configuration, a function for discriminating between the dew point and the frost point can be obtained. When calculating the humidity from the temperature to other parameters, the dew point or the frost point can be obtained. Based on this, it becomes possible to select an appropriate saturated vapor pressure.

7 and 8 show a second embodiment of the mirror-cooled dew point meter according to the present invention. This mirror-cooled dew point meter 1 'is a high-pressure vessel such as a dew point of hydrogen gas in a pressure tank, for example. It is the apparatus provided in order to measure the dew point temperature of the to-be-measured gas in the inside.

A mirror-cooled dew point meter 1 'of this embodiment is equipped with a measurement chamber 2' that constitutes a pressure vessel, and the measurement chamber 2 'is provided with an inlet 2i' and an outlet 2o '. The gas to be measured G is supplied / discharged through the inlet 2i ′ and the outlet 2o ′ as indicated by the arrows i and o.

  The mirror 3 'accommodated in the measurement chamber 2' is installed at the tip of a rod-shaped support 4s', and the temperature adjusting means 4 installed at the base end of the support 4s' penetrating the measurement chamber 2 '. ′, The mirror 3 ′ (surface 3a ′) is adjusted to a desired temperature.

  A temperature sensor (temperature measuring means) 5 'is installed in the vicinity of the mirror 3' in the support rod 3r ', and an output from the temperature sensor 5' is provided by a temperature meter 6 'connected to the temperature sensor 5'. (The temperature of the mirror 3 ') is displayed numerically.

  On the other hand, outside the measurement chamber 2 ', a light source 9' composed of an LED (light emitting diode) or the like and an imaging camera 10 'for photographing the surface 3a' of the mirror 3 'illuminated by the light source 9' are installed. The light source 9 'and the imaging camera 10' are arranged in such a manner that they face the projection glass window 2l 'and the observation glass window 2c' installed on the peripheral wall 2w 'of the measurement chamber 2', respectively. Yes.

  The imaging camera 10 'is connected to a controller 100', and image information from the imaging camera 10 'is sent to an image analysis unit (image analysis means) 101' of the controller 100 ', and an analysis result in the image analysis unit 101'. Based on the above, a control signal is sent from the temperature control section (temperature control means) 102 'of the controller 100' to the thermoelectric module 4 'to adjust the temperature of the mirror 3' described above.

Here, in the above-described mirror-cooled dew point meter 1 ′, for example, since the dew point is measured under a high pressure of 40 MPa or more, the thickness t of the peripheral wall 2w ′ in the measurement chamber 2 ′ takes pressure resistance into consideration. Accordingly, the observation glass window 2c ′ installed on the peripheral wall 2w ′ is also set to a thickness of about 10 to 20 mm in consideration of the pressure resistance.

For example, when hydrogen gas is handled as a gas to be measured, a light receiving element (photo sensor) in a conventional mirror-cooled dew point meter or the imaging camera 10 in the present embodiment, due to disadvantages such as strong corrosivity and hydrogen embrittlement. Since it is difficult to install a precision instrument such as' inside the measurement chamber 2 ', the imaging camera 10' is arranged outside the measurement chamber 2 'in the mirror-cooled dew point meter 1' of this embodiment. It corresponds by that.

On the other hand, as described above, the imaging camera 10 'is arranged outside the measurement chamber 2', so that the thick wall (about 10 to 20 mm) of the peripheral wall 2w 'and the observation glass window 2c' are sandwiched, so that an image is taken from the mirror 3 '. There is a disadvantage that the photographing distance to the camera 10 'is remarkably increased. Incidentally, in the conventional mirror-cooled dew point meter (see FIG. 10), the distance between the light source (LED), the mirror and the light receiving element cannot be set long, and is usually installed at a short distance of 5 cm or less.

Therefore, in the mirror-cooled dew point meter 1 ′ in the present embodiment, the surface 3a ′ of the mirror 3 ′ can be reliably photographed even through the observation glass window 2c ′ having a thickness (about 10 to 20 mm). The imaging camera 10 'employs a long focal length type optical system.

According to the mirror-cooled dew point meter 1 ′ having the above-described configuration, by adopting a long focal length type in the optical system of the imaging camera 10 ′, for example, measurement of the wall thickness in order to perform dew point measurement under high pressure. The dew point of the gas to be measured can be measured even in a situation where the distance from the mirror to the imaging camera is set large, such as a mirror-cooled dew point meter equipped with a chamber.

Here, chilled mirror dew-point meter 1 described above 'configuration of the image pickup camera 10' than the optical system is long focal length type, a chilled mirror dew-point meter 1 of the first embodiment shown in FIG. 1 There is basically no change, and the operation mode (image analysis, temperature control, etc.) for measuring the dew point of the gas to be measured is basically the same as the mirror-cooled dew point meter 1 in the first embodiment. There is no place.

That is, in the mirror-cooled dew point meter 1 ′ in the second embodiment, the optical system of the imaging camera 10 ′ is a long focal length type, so that even if it has a structure equipped with a thick measurement chamber, there is no problem. It becomes possible to measure the dew point of the gas to be measured under high pressure (for example, 40 MPa).

Further, in the mirror-cooled dew point meter 1 ′ in the second embodiment, the measurement accuracy of the dew point in the measurement gas G can be improved in the same manner as the mirror-cooled dew point meter 1 in the first embodiment described above. It is possible to measure the dew point in the gas G to be measured in a short time.

FIG. 9 shows a third embodiment of the mirror-cooled dew point meter according to the present invention, and this mirror-cooled dew point meter 1 ″ is an apparatus provided for the purpose of making the appearance shape as compact as possible. It is.

The mirror-cooled dew point meter 1 ″ of this embodiment is equipped with a measurement chamber 2 ″ through which the gas G to be measured is supplied / exhausted, and the measurement chamber 2 ″ includes an inlet 2i ″ and an outlet 2o. ”, And the gas G to be measured is supplied / discharged through the inlet 2i ″ and the outlet 2o ″ as indicated by the arrows i and o.

  The mirror 3 ″ housed in the measurement chamber 2 ″ is installed at the tip of a support 4s ″ having a rod shape with a diameter of 2 mm to 3 mm, and temperature adjusting means such as a coil heater provided on the support 4s ″. 4 ″ adjusts the mirror 3 ″ (surface 3a ″) to a desired temperature.

  The base end of the rod-shaped support 4s ″ described above is fixedly installed on a base 4b ″ that closes the measurement chamber 2 ″, and air-cooling fins 4f ″ for heat radiation are provided outside the base 4b ″. ing.

  Further, a temperature sensor (temperature measuring means) 5 ″ is installed in the vicinity of the mirror 3 ″ in the support 4s ″, and a temperature meter 6 ″ connected to the temperature sensor 5 ″ is used to remove the temperature sensor 5 ″ from the temperature sensor 5 ″. The output (temperature of mirror 3 ″) is displayed numerically.

  On the other hand, the measurement chamber 2 ″ is provided with a light source 9 ″ composed of an LED (light emitting diode) and the like, and an imaging camera 10 ″ for photographing the surface 3a ″ of the mirror 3 ″ illuminated by the light source 9 ″. Yes.

  The imaging camera 10 ″ is connected to a controller 100 ″, and image information from the imaging camera 10 ″ is sent to an image analysis unit (image analysis unit) 101 ″ of the controller 100 ″, and an analysis result in the image analysis unit 101 ″. Based on the above, a control signal is sent from the temperature control section (temperature control means) 102 ″ of the controller 100 ″ to the temperature adjustment means 4 ″, and the temperature of the mirror 3 ″ (surface 3a ″) is adjusted.

Here, in the mirror cooled dew point meter 1 ″ of this embodiment, the diameter of the mirror 3 ″ installed at the tip of the support 4s ″ is set to a very small dimension of about 2 mm to 3 mm. The support 4s "has a thin rod shape corresponding to 3".

Further, in the mirror-cooled dew point meter 1 ″ of the present embodiment, since the diameter is about 2 mm to 3 mm as described above, the surface 3a ″ of the mirror 3 ″ having an extremely small area can be reliably photographed. A microscope type optical system is employed for the imaging camera 10 ″.

By the way, the diameter of the mirror in a general mirror-cooled dew point meter is usually larger than that of the mirror 3 ″ of the mirror-cooled dew point meter 1 ″ in this embodiment, and is set to a diameter of about 6 mm to 10 mm, for example. Yes. Incidentally, in the conventional mirror-cooled dew point meter (see FIG. 10), the optical axis for illuminating the mirror cannot be narrowed down to a diameter of 5 mm or less because of the structure of the light source (LED).

For this reason, in the conventional general mirror-cooled dew point meter , the surface area of the mirror is large due to the large diameter, and after the start of supply of the gas to be measured, condensation is formed on the surface of the mirror, There is an inconvenience that a long measurement time of, for example, about 1 to 2 hours is required until the dew point temperature of the gas to be measured is detected.

On the other hand, in the mirror surface cooling type dew point meter 1 ″ in this embodiment, the diameter of the mirror 3 ″ is small and the area of the surface 3a ″ of the mirror 3 ″ is narrow as described above. The measurement time from the start of supply to the detection of the dew point temperature of the gas G to be measured after dew condensation is formed on the surface 3a "of the mirror 3" can be significantly reduced to, for example, about 30 minutes. It becomes possible.

Also, in the general mirror-cooled dew point meter , the diameter of the mirror is large as described above, which leads to an increase in the shape of the entire apparatus, and in particular to the increase in the size of the components that make up the periphery of the mirror. Along with this, the heat capacity increases, resulting in inconvenience that the responsiveness during heating / cooling is poor and the temperature adjustment is difficult.

On the other hand, in the specular cooling type dew point meter 1 ″ in this embodiment, the diameter of the mirror 3 ″ is as small as about 2 mm to 3 mm as described above, and the support 4s ″ supporting the mirror 3 ″ has a thin rod shape. As a result, the heat capacity of the components that form the periphery of the mirror is greatly reduced, and the response (temperature followability) during heating / cooling is extremely good.

Incidentally, in the mirror cooled dew point meter 1 ″ of the present embodiment, a coil heater as the temperature adjusting means 4 ″ is wound around the thin rod-shaped support 4s ″, and a sheath type temperature sensor as the temperature sensor 5 ″ is incorporated. As a result, the components constituting the periphery of the mirror 3 ″ are made as compact as possible to suppress the heat capacity to a small level, thereby achieving good responsiveness to the temperature change during heating / cooling.

Further, in the mirror-cooled dew point meter 1 ″ according to the present embodiment, since the diameter of the mirror 3 ″ is small as described above, the entire apparatus can be made compact. In particular, the measurement chamber 2 through which the measurement gas G is supplied / exhausted. Since "" is reduced in size and the internal volume of the measurement chamber 2 "is reduced, a very small amount of the measurement gas G to be sampled at the time of measurement is sufficient.

Furthermore, in a general mirror-cooled dew point meter , when measuring the dew point of the gas to be measured with a low water content, the dew point requires 3 to 4 hours for dew condensation. In the mirror-cooled dew point meter 1 ″ of the present embodiment that achieves this, the waiting time until condensation can be shortened to about 30 minutes by downsizing the measurement chamber 2 ″.

Here, the configuration of the above-described mirror-cooled dew point meter 1 ″ is the same as that of the mirror-cooled dew point meter 1 in the first embodiment shown in FIG. 7. There is basically no difference from the mirror-cooled dew point meter 1 'in the second embodiment shown in FIG. 8, and the operation mode for measuring the dew point of the gas to be measured (image analysis, temperature control, etc.) ) Is basically the same as the above-described mirror-cooled dew point meter 1 and mirror-cooled dew point meter 1 ′.

That is, in the mirror-cooled dew point meter 1 ″ in the third embodiment, the optical system of the imaging camera 10 ″ is a microscope type, thereby minimizing the diameter of the mirror 3 ″ (the surface 3a ″ area). The time required for measuring the dew point of the measurement gas G can be greatly shortened. In addition, the mirror 3 ″ and the components around the mirror 3 ″ are miniaturized as much as possible to keep the heat capacity small, and during heating / cooling Responsiveness to the amount of temperature change can be improved.

Further, the cooled mirror dew point meter 1 "in the third embodiment, similarly to the chilled mirror dew-point meter 1 'in the first chilled mirror dew-point meter 1 in the embodiment of, and the second embodiment described above Of course, the measurement accuracy of the dew point in the gas to be measured G can be improved, and the dew point in the gas to be measured G can be measured in a short time.

  In each of the embodiments described above, an example is shown in which image information captured by an imaging camera is processed by an image analysis method using an “absolute value difference method” to determine whether or not condensation has occurred. However, it goes without saying that various image analysis methods other than the above-described “image analysis method using the absolute value difference method” can also be effectively employed.

  Further, in each of the above-described embodiments, each has an imaging camera equipped with a dedicated optical system, but the optical system (interchangeable lens) can be exchanged for the camera body, and the standard type, long focal length By selecting an appropriate optical system (interchangeable lens) such as a type or a microscope type and attaching it to the camera body, it is possible to deal with dew point meters of various specifications.

Furthermore, the range of use of the “ mirror-cooled dew point meter ” related to the present invention is not limited to the above-described embodiments. For example, low dew point gas measurement in a dry room, performance confirmation of a dry air line, various gas cylinders It can be effectively applied in various technical fields, such as moisture content measurement, dew point management in carburizing furnace and temperature and humidity chamber, humidity data management in R & D field, and humidity calibration standard (humidity standard). Of course.

1 is a cross-sectional side view conceptually showing a first embodiment of a mirror-cooled dew point meter according to the present invention. The flowchart which shows the measurement process of the dew point in the mirror surface cooling-type dew point meter of this invention. The conceptual diagram which shows the picked-up image by the imaging camera of the mirror surface cooling-type dew point meter concerning this invention. (a) And (b) is a conceptual diagram which shows the 1st picked-up image by an imaging camera, and the 2nd picked-up image. (a) And (b) is a conceptual diagram which shows the 1st picked-up image by an imaging camera, and the n-th picked-up image. The graph which showed the brightness | luminance gradation of each picked-up image at the time series at the time of measurement of the specular cooling type dew point meter concerning this invention. Sectional side view which shows notionally 2nd Example of the mirror surface cooling-type dew point meter in connection with this invention. VIII-VIII sectional view taken on the line in FIG. Sectional side view which shows notionally 3rd Example of the mirror surface cooling-type dew point meter concerning this invention. The conceptual cross section side view which shows the conventional mirror surface cooling dew point meter .

Explanation of symbols

1, 1 ', 1 "... mirror cooled dew point meter ,
2, 2 ', 2 "... measurement chamber,
2i, 2i ', 2i "... inlet,
2o, 2o ', 2o "... discharge port,
3, 3 ', 3 "... mirror,
3a, 3a ', 3a "... surface,
4 ... Thermoelectric module (temperature adjustment means)
4 ', 4 "... temperature adjusting means,
4s, 4s', 4s "... support,
5, 5 ', 5 "... temperature sensor (temperature measuring means),
6, 6 ', 6 "... temperature meter (temperature display means),
7 ... Base plate,
8 ... Insulation block,
9, 9 ', 9 "... light source,
10, 10 ', 10 "... imaging camera,
100, 100 ', 100 "... controller,
101, 101 ′, 101 ″... Image analysis unit (image analysis means),
102, 102 ′, 102 ″... Temperature control unit (temperature control means),
X1, X2,... Xn ... taken image,
Aa to Rr: Pixel (pixel),
G: Gas to be measured.

Claims (5)

A measurement chamber for supplying / exhausting the gas to be measured and circulating the gas to be measured inside;
A mirror that is housed and installed inside the measurement chamber and is exposed to the gas to be measured flowing;
Temperature adjusting means for adjusting the temperature of the mirror;
Temperature measuring means for measuring the temperature of the mirror;
Temperature display means for displaying the temperature of the mirror;
A light source that illuminates the surface of the mirror;
An imaging camera for photographing the surface of the mirror;
Image analysis means for determining the occurrence of condensation / frost formation on the surface of the mirror based on image information from the imaging camera;
Temperature control means for controlling the operation of the temperature adjusting means to keep the temperature of the mirror constant based on the result of determination by the image analysis means;
A surface-cooled dew point meter comprising: The image analysis means sequentially compares the luminance of all pixels in the first photographed image taken in time series by the imaging camera with the luminance of all pixels in each of the second and subsequent photographed images. Obtaining the luminance gradation of each captured image by the absolute value difference method that compares the absolute values of the luminance differences in pixels, and detecting the occurrence of condensation based on the change over time of the luminance gradation in each captured image The surface-cooling type dew point meter according to claim 1. The surface-cooling type dew point according to claim 1, wherein the image analysis means distinguishes condensation and frost generated on the surface of the mirror by performing color analysis on image information from the imaging camera. Total. The surface-cooled dew point meter according to claim 1, wherein the imaging camera is provided with a long focal length type optical system. The surface-cooling dew point meter according to claim 1, wherein the imaging camera includes a microscope type optical system.

Images