JPH0643951B2 - Deposit detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deposit detection device for detecting whether or not substances such as particles and dust exist in an atmosphere by deposition, and more specifically, to a deposit detection device. The present invention relates to a deposit detecting means that locally heats and thermally decomposes a substance such as a carbide present in an atmosphere to generate a secondary product, and detects deposition of the secondary product. In particular, the present invention relates to a deposit detector suitable for use as a dust detector, a soot detector, a window glass haze detector, an oil film detector, and the like.

Conventional technology Most conventional dust detectors and soot detectors directly measure the presence of substances present in the atmosphere, and their devices are often large and complicated, making their usage difficult. There were many problems such as the cost and the cost.

The present invention has been made in view of the above points, and a detection device capable of detecting the presence of a substance in an atmosphere based on a novel principle by solving the above-mentioned drawbacks of the conventional technology. The purpose is to provide.

Configuration According to the present invention, the atmosphere is locally heated to deposit the substance existing in the atmosphere, and the presence of the substance in the atmosphere is detected by monitoring the deposition state. Particularly, in a preferred embodiment of the present invention, a carbon compound existing in the atmosphere is detected, and the carbon compound is heated to be thermally decomposed and the secondary product thereof is deposited at a predetermined position. Detects the presence of carbon compounds. That is, in the present invention, when the carbon compound gas or mist is present in the atmosphere such as the air, it is thermally decomposed by being heated by the heater and the decomposed substance is deposited around the heater. The present invention has been made by paying attention to such a phenomenon, and it is possible to easily confirm the presence of a carbon compound floating in an atmosphere such as air, and from the deposition state to the atmosphere. It is also possible to measure the content of carbides included in the.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a deposit detecting apparatus constructed according to one embodiment of the present invention, which has a substrate 1 made of a predetermined substance, for example, silicon, and an insulating layer on the upper surface thereof. As a result, a silicon dioxide layer 2 is deposited.
The insulating layer 2 is patterned into a desired shape by using a known photolithography technique, and the substrate 1 is selectively etched using the patterned insulating layer 2 as a mask.
A recess 1a is defined in the substrate 1 and a bridge structure 2a is formed. In this embodiment, the crosslinked structure 2a is formed of a part of the patterned insulating layer 2.
Therefore, the crosslinked structure 2a has a shape protruding in the air,
Its heat capacity is extremely small. Moreover, the etching of the substrate 1 may be a combination of isotropic etching and anisotropic etching.
Alternatively, only anisotropic etching may be used.

The bridge structure 2a extends in the air for a predetermined length by the recess 1a, and a heater 3 as a heating unit is attached and formed on the bridge structure 2a. The heater 3 can be formed, for example, by adhering a desired substance such as Pt, and in the present embodiment, an electric current is passed through the heater 3 to cause Joule heat generation, and the heat causes the ambient temperature to increase. Heat the atmosphere. Note that the heater 3 can be configured to surround the periphery thereof with an insulating material such as silicon dioxide. The current applied to the heater 3 may be continuous, but it is preferable to apply it as a pulse current.

In the structure as described above, when an electric current is applied to the heater 3, the heater 3 generates heat and heats the surrounding atmosphere, and as a result, the substance existing in the atmosphere is also heated to cause thermal decomposition and secondary generation. A substance is generated and deposited as a deposit 5 on the surface of the substrate 1 or the insulating layer 2 around the heater 3. In this case, since the heater 3 is in a high temperature state, the deposit 5 is hardly deposited, but since the heater 3 is formed on the bridge structure 2a and its heat capacity is small, the insulating layer 2 and the substrate around the heater 3 are formed. The influence of the radiant heat on 1 is considerably small, and the insulating layer 2 and the substrate 1 around the heater 3 are maintained at a considerably low temperature as compared with the heater 3 and the bridge structure 2a.
Therefore, the substance in the atmosphere locally heated by the heater 3 is deposited as the deposit 5 on the surfaces of the insulating layer 2 and the substrate 1 around the heater 3. Therefore, in this embodiment, light from a light source (not shown) is reflected by the deposit 5,
It is detected that the deposit 5 is deposited by monitoring the reflected light. In this case, the deposition amount of the deposit 5 is related to the intensity of the reflected light, and therefore the amount of the deposit 5 and the content in the atmosphere can be measured from this reflected light.

FIG. 2 shows a deposit detecting device constructed according to another embodiment of the present invention. Since this embodiment also has basically the same configuration as the apparatus of FIG. 1 described above, the same numbers are attached to the same elements. That is, the apparatus of FIG. 2 also has a substrate 1 made of a substance such as silicon,
An insulating layer 2 made of silicon dioxide or the like is formed on the upper surface thereof. In this embodiment, a selected portion of the substrate 1 is etched from its bottom to the insulating layer 2 to form a removed portion 1b. By providing the removed portion 1b, the bridge structure 2a is defined in a part of the insulating layer 2. A heater 3 is formed at least partially on the bridge structure 2a, so that the heat capacity of the heater 3 is minimized as much as possible. As in the case of FIG. 1,
The heater 3 is made of a desired substance, and is configured to generate Joule heat by passing an electric current through it. If desired, the heater 3 may be surrounded by an insulating material such as silicon dioxide.

In the configuration of FIG. 2, the heater 3 locally heats the atmosphere, so that the deposit 5 is deposited on the insulating layer 2 in the vicinity of the heater 3 from the substance existing in the atmosphere. Therefore, the detection light beam 8 from the light source (not shown) is irradiated from the lower side of the bridge structure 2a of the insulating layer 2, and the resistant material 5 exists based on the transmittance of the beam through the deposit 5. And, if desired, the amount is detected. In this way, the second
The illustrated embodiment is a light-transmissive type, and has a crosslinked structure 2a of the insulating layer 2.
Since light is transmitted therethrough, it is desirable that the insulating layer 2 is transparent at least in the portion of the crosslinked structure 2a.

FIG. 2 shows a reflection type detection device 10 applicable to the present invention. This detection device 10 has a light source 11 composed of a light emitting diode or the like and a light receiving element 12 such as a phototransistor or CdS. The light emitted from the light source 11 is reflected by the insulating layer 2, and the reflected light is received by the light receiving element 12 to detect that a deposit is deposited on the insulating layer 2. On the other hand, FIG. 4 shows a transmission type detection device 10, which also has a light source 11 and a light receiving element 11, but the deposit is in the optical path from the light source 11 to the light receiving element 12. The amount of light that is positioned and that passes through the deposit is measured to detect the deposition state.

FIG. 5 shows a specific example of the reflection-type structure of the present invention, in which the deposit detection chip 13 is arranged in the center of the base 15, and a pair of columns are provided from the bottom of the base 15. 16,
16 are extended. A holding frame 17 is further mounted on the upper surface of the base 15, and holds the light source 11 and the light receiving element 12 in a juxtaposed relationship with each other. Furthermore,
A protective net 18 is provided so as to surround the whole thereof. In this configuration, the light emitted from the light source 11 is reflected by the deposition portion of the chip 13, and the reflected light is incident on the light receiving element 12. Also, chip 13
It is possible to use the one having the structure shown in FIG. 1, that is, the heater 3 as the heating unit, and
It has a deposition part composed of the insulating layer 2 and the like on which the deposit 5 is deposited. Therefore, it is possible to detect the presence and the amount of such a deposit deposited on such a deposit by the reflected light received by the light receiving element 12.

Similarly, FIG. 6 shows a specific example of the transmissive type of the present invention, which basically has the same configuration as the reflective type of FIG. Therefore, the same reference numerals are given to the same components. In the case of this example, the light source 1
1 is arranged in the center of the base 15, and the chip 13 is provided on the light source 11. Further, the light receiving element 1
2 is held by a holding frame 17 positioned vertically above the light receiving element 11. The chip 13 is, as described above,
The heating unit and the deposition unit adjacent to the heating unit are provided. In this configuration, the light from the light source 11 passes through the deposition portion of the chip 13 and enters the light receiving element 12.

7 and 8 show another embodiment of the transmission type device of the present invention, and FIG. 8 is a schematic sectional view taken along line xx shown in FIG. This apparatus also has a substrate 1 made of a substance such as silicon, and an insulating layer 2 made of silicon dioxide or the like is deposited on the upper surface of the substrate 1.
The insulating layer 2 is patterned into a predetermined shape to form an opening and a cantilever-shaped overhanging portion 2b pattern. The substrate 1 is selectively etched from this opening to form a recess 1a, and thus the overhanging portion 2b formed by a part of the insulating layer 2 is configured to overhang in the air. The heater 3 is formed by depositing a predetermined substance on the insulating layer 2 including the overhanging portion 2b.
Has a heating portion 3a formed on the overhanging portion 2b and a pair of heater electrode portions 3b, 3b extending from the heating portion 3a and formed on the insulating layer 2. The heat generating portion 3a includes the heater 3
It is formed to be narrower than the other portions, and is configured to generate Joule heat when the resistance value in that portion is increased and current is applied. In addition, in the present embodiment, the heat generating portion 3a is formed in a meandering shape to obtain the heat generation amount per unit area. With such a configuration, the heater 3 can be formed of the same material, which is advantageous in manufacturing.

A light receiving element layer 22 made of a photosensitive material is formed on the insulating layer 2 at a predetermined position around the recess 1a. In this example, this layer 22 is composed of CdS. in this case,
CdS is applied and then it is sintered. A pair of output electrodes 21a connected to both ends of the light receiving element layer 22,
21b is provided, and the bonding wire 23 is connected to the other end of the output electrode 21b. On the other hand, as shown in FIG. 8, a light source 11 such as a light emitting diode is arranged above the light receiving element layer 22. In addition, these output electrodes 21
It is preferable that a and 21b are formed of the same material as the heater 3.
The light receiving element layer 22 functions as a deposition portion, as described later.

In such a configuration, the surrounding atmosphere is locally heated by passing a current through the heater 3. In this case, the heating portion 3a of the heater 3 and the overhanging portion 2b carrying the heating portion 3 are in a high temperature state, but since their heat capacity is small and the radiant heat is small, the other portions are kept in a relatively low temperature state. To be done. Therefore, the light receiving element layer 22 is also maintained at a relatively low temperature, and as a result, the secondary product generated by the thermal decomposition of the substance in the atmosphere locally heated by the heater 3, particularly the carbon compound, is Light receiving element layer 2
2 is deposited on. Therefore, the light receiving element layer 22 acts as a deposition portion and deposits a deposit on the surface thereof. Thus, when the deposit is deposited on the light receiving element layer 22, the light source 1
Since the amount of light received from No. 1 changes, it is possible to detect the presence or absence of deposits and the amount thereof, and thus substances such as carbon compounds existing in the atmosphere.

FIG. 9 shows an example of the system of the device of the present invention,
The transmission type deposit detection device 31 includes a light source 11 and a light receiving element 1.
It is interposed between the two. The device 31 has a micro-heater-shaped heating unit as described above and a deposition unit that deposits a deposit that is deposited by heating to an atmosphere. Light from the light source 11 passes through the deposition unit and the light receiving element. It is incident on 12. The light source 11 is connected to the power source 33 via the resistor R, and a drive current is supplied to the light source 11 based on a predetermined timing from the timing circuit 34. Device 31
A heater power supply 35 for applying a pulse current to the heater is provided and is connected to a timing circuit 36. Therefore, the pulse current is applied from the heater power supply 35 to the heater of the device 31 at a predetermined timing. The output from the light receiving element 12 is amplified by the amplifier 32 and supplied to the signal generator 37.

According to the present invention, it is possible to detect a trace amount of component contained in the atmosphere in a short time, and as shown in FIG. 10, the detection output Vout depends on its concentration.
It is possible to calculate the content of that component. Tenth
As shown by the solid line in the figure, when the heater is not driven, the detected output Vout shows almost no change over time, but when the heater is driven, the detected output Vout is the concentration of carbon compound contained in the atmosphere. Is 1 ppm or 10 pp
Depending on whether it is m or 100 ppm, it changes as shown by the dotted line, the one-dot chain line, and the two-dot chain line, respectively. Therefore, it is understood that the concentration can be calculated from the output Vout.

Effect As described above in detail, according to the present invention, it is possible to detect the presence or absence and the amount of the deposit. It is also possible to detect substances present in the atmosphere, especially carbon compounds. According to this device, it is possible to detect deposits with high accuracy and at high speed.

The specific embodiments of the present invention have been described above in detail, but the present invention should not be limited to these specific examples, and various modifications can be made without departing from the technical scope of the present invention. Of course, it is possible.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a reflection type detection device constructed according to one embodiment of the present invention, and FIG. 2 is a transmission type detection device constructed according to another embodiment of the present invention. 3 is a schematic sectional view showing a reflection type detection optical system, and FIGS. 3 and 4 are explanatory views showing reflection type and transmission type detection optical systems, respectively. FIG. 5 is a schematic view showing an example of the reflection type detection device of the present invention. FIG. 6 is a schematic view showing an example of the transmission type detection device of the present invention, and FIG. 7 is a schematic plan view showing an embodiment in which a light receiving element is integrally incorporated in the transmission type detection device, FIG. 8 is a schematic view showing a cross section along the line xx shown in FIG. 7 and a positional relationship with the light source 11, and FIG. 9 is an example of a system of the transmission type detection apparatus of the present invention. The explanatory diagram shown in FIG. 10 is a graph showing the detection characteristics of the present invention. (Explanation of Codes) 1: Substrate 2: Insulating Layer 2a: Crosslinked Structure 2b: Overhanging Part 3: Heater 5: Deposit 10: Detection Optical System

Claims (8)

[Claims] 1. A heating section for heating an atmosphere, a deposition section located in the vicinity of the heating section, for depositing a substance existing in the atmosphere by heating by the heating section, and a deposition section on the deposition section. A deposit detecting device for detecting whether or not a deposit has been deposited. 2. An apparatus according to claim 1, wherein said detecting means is an optical detecting means. 3. The heating unit according to claim 1 or 2, wherein a cross-linking structure is formed on a part of the substrate, and the heating unit is formed by adhering at least on the cross-linking structure. And the device. 4. The crosslinked structure according to claim 3, wherein an insulating layer is formed on the substrate, the insulating layer is patterned into a predetermined shape, and the substrate is selectively etched. A device characterized by being formed. 5. The insulating layer according to claim 3, wherein an insulating layer is formed on one surface of the substrate, and the substrate is selectively etched from the opposite surface to form the crosslinked structure. A device characterized by. 6. The apparatus according to claim 3, wherein the deposition section is also set on the substrate. 7. The apparatus according to claim 2, wherein the optical detecting means is of a reflection type, and the degree of deposition is detected by the degree of reflection of light on the deposition portion. 8. The optical detecting means according to claim 2, wherein the optical detecting means is a transmission type, and the degree of deposition is detected by the degree to which light passes through the deposits deposited on the depositing portion. And the device.