JP2011007600A - Measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring instrument which can perform high-precision measurement.SOLUTION: The measuring instrument 1 includes: a housing 2 which incorporates a measuring circuit 3 having a semiconductor device 32 for performing measurement processing and has a hermetically sealed structure; a fan 6 for stirring the gas within the housing 2; a dehumidifying agent 7 for removing the water within the housing 2; a first heat sink 4 which is provided in close contact with the semiconductor device 32 to radiate the heat of the semiconductor device 32 into the inside of the housing 2; and a second heat sink 5 which is provided on the inner surface of the housing 2 to radiate the heat within the housing 2 into the outside of the housing 2.

Description

  The present invention relates to a measuring instrument incorporating a measuring circuit.

Conventionally, a housing structure containing a semiconductor component (measurement circuit) or the like that generates heat by performing a predetermined process is known (see, for example, Patent Documents 1 and 2).
The housing structure described in Patent Document 1 includes a cover that closes an opening formed above the housing, and includes a bottomed cylindrical body so as to be close to a built-in semiconductor component. The cover has a vent hole at a position facing the opening of the bottomed cylindrical body. Thereby, the heat generated from the semiconductor component is transmitted from the bottomed cylinder to the air in the bottomed cylinder. Further, since the vent is provided in the cover, the air in the bottomed cylinder is discharged from the vent to the outside. As described above, excessive heat generation is suppressed by releasing the heat of the semiconductor component to the outside through the bottomed cylinder, the inside of the cylinder, and the vent hole.

  The casing described in Patent Document 2 has a hermetically sealed structure, and absorbs and dehumidifies material that allows only moisture to flow back and forth inside the casing, air blowing means that circulates the air in the casing, and cools the air in the casing And a cooler. In this housing, the moisture in the housing absorbs or releases moisture according to the humidity in the housing to control the humidity in the housing. Moreover, the cooler prevents the temperature in the housing from becoming high.

JP-A-8-125364 Japanese Patent Laid-Open No. 9-138044

Here, as a semiconductor component, for example, there is a measurement circuit that measures a minute current, and such a measurement circuit has an error in a measurement result because a semiconductor element constituting the circuit is affected by temperature and humidity changes. It is easy to occur.
By the way, in the housing | casing structure of patent document 1, since the heat | fever from a semiconductor component is thermally radiated outside via a ventilation hole, the temperature rise in a housing | casing can be suppressed, but the structure which adjusts the humidity in a housing | casing Not equipped. Since the cover only blocks the opening of the housing, there is a possibility that external air may enter the housing, and it is affected by the humidity environment of the external air, and the humidity inside the housing can be kept constant. There is a problem that you can not. Therefore, when the measurement circuit is provided in the housing structure as in Patent Document 1, there is a problem that an error occurs in the measurement result due to the influence of the humidity change.
Moreover, in the housing | casing described in patent document 2, although a cooler is provided in a housing | casing and the air in a housing | casing is cooled, there exists a possibility that condensation may generate | occur | produce in a cooler. Further, since the casing has a sealed structure, there is a problem that the humidity in the casing tends to increase when condensation occurs. Therefore, similarly to Patent Document 1, when a measurement circuit is provided in a conventional casing as in Patent Document 2, there is a problem that an error occurs in the measurement result of the measuring circuit due to the influence of humidity change in the casing.

  The objective of this invention is providing the measuring device which can implement a highly accurate measurement.

  The measuring instrument of the present invention has a built-in measurement circuit provided with a semiconductor element for performing measurement processing, removes moisture in the casing, a casing having a sealed structure, a fan for stirring the gas in the casing, and the like. A dehumidifying agent is disposed in close contact with the semiconductor element, a first heat dissipating means for radiating the heat of the semiconductor element into the casing, and an inner surface of the casing to dissipate the heat in the casing. And a second heat radiating means for radiating heat to the outside of the housing.

In the present invention, since the casing has a sealed structure, external air does not enter the casing and is not affected by humidity outside the casing, so that a change in humidity inside the casing can be prevented. In addition, since the dehumidifying agent is provided in the housing, the humidity in the housing can be kept low. As a result, the influence of humidity on the measurement circuit can be effectively reduced, voltage fluctuation due to humidity change in the semiconductor element does not occur, and inconvenience such as an error in the measurement result can be prevented.
Further, since the first heat radiating means is disposed in close contact with the semiconductor element, the first heat radiating means can dissipate heat generated from the semiconductor element into the housing and is disposed within the housing. The gas in the housing is agitated by the fan. As a result, the temperature distribution in the housing becomes uniform, and high-temperature gas is not trapped in the vicinity of the measurement circuit, so that the temperature influence on the measurement circuit can be reduced. And the 2nd thermal radiation means arrange | positioned at the inner surface of a housing | casing transfers the heat | fever in a housing | casing to the outer surface of a housing | casing, and the said heat is radiated | emitted from the outer surface of a housing | casing to the exterior. Thereby, the temperature in a housing | casing can be reduced uniformly and a temperature rise can be suppressed more effectively.
Therefore, it is possible to improve the measurement accuracy of a measuring instrument including a measurement circuit that easily causes an error in measurement results due to temperature and humidity changes.

  In the measuring instrument of the present invention, in the housing, a first region in which the first heat dissipation unit and the measurement circuit are disposed, a second region in which the second heat dissipation unit is disposed, And a partition plate provided to face the measurement circuit, and communicates between the first region and the second region across a central portion of the partition plate facing the measurement circuit. A pair of openings is formed, and the fan passes through the first region, one of the pair of openings, the second region, and the other of the pair of openings again to return to the first region. Preferably, the second heat radiating means is disposed in the flow path of the gas flowing in the second region.

In the present invention, the inside of the housing is partitioned into a first region and a second region by a partition plate, and a flow path for circulating the gas in the housing from the first region to the second region is formed by a fan. Therefore, the temperature distribution in the housing can be made more effective and uniform.
Further, the gas that has absorbed the heat released from the first heat dissipating means disposed in the first region flows toward the second heat dissipating means disposed in the second region. Here, since the second heat radiating means is disposed in the flow path, that is, between the pair of openings of the partition plate, the heat of the gas flowing in from the first region is reliably supplied to the second heat radiating means. It is absorbed and dissipated outside the housing.
As described above, the temperature inside the housing can be more effectively uniformed and the heat radiation from the second heat radiating means can be surely radiated to the outside of the housing, so that the influence on the measurement circuit due to the temperature rise can be further suppressed. .

  In the measuring instrument of the present invention, it is preferable that the fan is disposed in the second region, and at least one pair of the second heat radiation means is disposed with the fan interposed therebetween.

  In the present invention, since a pair of the second heat radiating means are disposed, the heat in the housing can be radiated efficiently from the outside. In addition, since the fan is disposed between the second heat radiating means, when the gas that has traced one of the second heat radiating means passes through the fan in the second region, the partition plate serves as a wall surface. Therefore, the flow path for directing the gas to the other second heat radiating means can be formed reliably, and the temperature in the housing can be made more uniform.

In the measuring instrument of the present invention, it is preferable that a gas having a specific gravity larger than that of the air outside the casing is enclosed in the casing.
In the present invention, a gas whose specific gravity is larger than the specific gravity of the air outside the housing is sealed in the housing, so air intrusion from outside the housing into the housing can be more reliably suppressed due to a difference in specific gravity inside and outside the housing. can do. Therefore, the humidity change of the gas in the housing can be more reliably suppressed, the influence of the humidity on the measurement circuit can be effectively eliminated, and the measurement accuracy can be improved.

The figure which shows typically the inside of the measuring device which concerns on one Embodiment of this invention. The figure which shows typically the inside of the measuring device which concerns on the modification of this invention.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
[Configuration of measuring instrument]
FIG. 1 is a diagram schematically showing the inside of the measuring instrument 1.
The measuring instrument 1 in this embodiment is a small measuring instrument that detects a minute current, voltage, and the like, and can be used for, for example, a portable current-voltage measuring instrument. The measuring device 1 is not limited to this, and can be applied to any measuring device that measures other physical quantities by measuring a weak current or voltage, such as a light meter using a photoelectric exchange element. It can also be applied to. Note that “upper”, “lower”, “left”, and “right” described below correspond to upper, lower, left, and right in the view of FIG.
As shown in FIG. 1, the measuring instrument 1 includes a housing 2, a measurement circuit 3 built in the housing 2, a first heat sink 4 as a first heat radiating means, and a second heat radiating means. The second heat sink 5, the fan 6, and the dehumidifying agent 7 are provided. The power supply such as a button battery that supplies power to the measurement circuit 3 and the like, and the control board that is connected to the measurement circuit 3 and controls the fan 6 and the like are not particularly illustrated.

The housing 2 constitutes the exterior of the measuring instrument 1 and has a sealed structure that blocks outside air. Further, third heat sinks 8 are respectively disposed on the back surfaces (outer surface) of the pair of second heat sinks 5 disposed on the inner surface side of the upper surface of the housing 2. The third heat sink 8 radiates the heat in the housing 2 transmitted to the outer surface of the housing 2 to the outside. In the present embodiment, the third heat sink 8 is integrated with the housing 2, but may be attached to the housing 2 via grease having high thermal conductivity. Moreover, although the example where the housing 2 is provided with the third heat sink 8 is shown, any heat radiating means for radiating the heat transmitted to the housing to the outside may be used. For example, a heat radiating sheet, a heat pipe, etc. A configuration in which heat dissipation means is provided, or a combination of these with a heat dissipation sheet, a heat pipe, a heat sink, or the like may be used.
Although not particularly illustrated, the housing 2 includes a lid and a main body closed by the lid, and the lid and the main body are sealed with a sealing material such as an O-ring, for example. ing.

The housing 2 is divided into a lower first region SP1 in which the first heat sink 4 and the measurement circuit 3 are disposed, and an upper second region SP2 in which the second heat sink 5 is disposed. A partition plate 9 is disposed.
The partition plate 9 is disposed at a central portion in the housing 2 in a side view so as to follow the upper surface and the lower surface of the housing 2. In addition to supporting the fan 6 and the dehumidifying agent 7, the partition plate 9 prevents the gas sucked into the fan 6 and the gas discharged from the fan 6 from flowing out below the partition plate 9. Further, a gap 10 as an opening is provided between the left and right end portions of the partition plate 9 and the left and right wall surfaces of the housing 2.
The gap 10 is a space provided for securing a gas flow path, which will be described later.

  An inert gas having a specific gravity larger than that of the air outside the housing 2 is enclosed in the housing 2, and argon gas is used in the present embodiment. In addition, for example, nitrogen gas or carbon dioxide gas may be used. The inert gas is preferably enclosed in the housing 2 at a pressure higher than atmospheric pressure. Thereby, it can suppress more reliably that the air outside the housing | casing 2 penetrate | invades in the housing | casing 2. FIG.

The measurement circuit 3 has a terminal (not shown), and connects a probe connected to the terminal to a measurement object to measure a power supply voltage. The measurement circuit 3 includes a circuit board 31 disposed on the lower surface of the housing 2 and semiconductor elements 32 mounted at two locations on the upper surface of the circuit board 31, and a control board (not shown) described above. It has.
The circuit board 31 is activated by power supply from a power source (not shown). A sensor S for measuring the temperature and humidity in the housing 2 is attached to the back surface of the circuit board 31.
The sensor S is activated when power is supplied to the circuit board 31 and outputs a signal corresponding to the temperature and humidity values to a control board (not shown). And a control board controls the rotation speed of the fan 6 according to the output signal. Further, when the temperature or humidity in the housing 2 exceeds a predetermined value, the start of the measuring instrument 1 is stopped by the control board.
The semiconductor element 32 is disposed on the circuit board 31 and is activated when power is supplied to the circuit board 31. Examples of the semiconductor element 32 include a CPU (Central Processing Unit) that controls the overall operation of the measuring instrument 1, a memory such as a RAM and a ROM that supports the processing of the CPU, and other various integrated circuits. Thus, the process of measuring the weak current input from the terminal is performed. The first heat sinks 4 are arranged in close contact with these semiconductor elements 32. The first heat sink 4 may be provided, for example, with respect to all the semiconductor elements 32 to be provided. For example, a CPU whose temperature rise is particularly increased by electronic processing, for example, a predetermined temperature or higher. Alternatively, it may be arranged only in the semiconductor element 32 that generates heat. With such a first heat sink 4, even when the semiconductor element 32 generates heat as a result of current measurement, the heat can be effectively radiated into the housing 2.

The first heat sink 4 is attached in close contact with the semiconductor element 32 in the first region SP1. The first heat sink 4 has a plurality of unillustrated radiating fins, and radiates heat generated from the semiconductor element 32 into the housing 2 from these radiating fins. Note that the first heat sink 4 may be attached to the semiconductor element 32 via a heat dissipation grease, a heat dissipation sheet, or the like having high thermal conductivity.
In the second region SP2, a pair of the second heat sinks 5 are disposed on the inner surface side of the upper surface of the housing 2 with the fan 6 sandwiched in the housing 2, and in a gas flow path (in FIG. 1). The white arrow). Similar to the first heat sink 4, the second heat sink 5 includes a plurality of heat-dissipating fins (not shown), absorbs heat in the housing by the heat-radiating fins, and transmits the heat to the outer surface of the housing 2. The heat transmitted to the outer surface of the housing 2 is radiated to the outside by the third heat sink 8 as described above. In the present embodiment, the second heat sink 5 is configured integrally with the housing 2. However, as with the first heat sink 4, the housing 2 is disposed via a heat radiation grease, a heat radiation sheet, or the like having high thermal conductivity. It may be attached to.
Each of the heat sinks 4, 5, and 8 described above includes a plurality of plate-like heat radiation fins, but may have other shapes that can secure a large surface area. In addition to the configuration in which each of the first heat sink 4 and the second heat sink 5 functions as a heat radiating unit, the heat radiating sheet, the heat radiating grease, the first heat sink 4 and the second heat sink 5 In addition, for example, the heat dissipating means may have a structure in which only a heat dissipating sheet or heat dissipating grease is provided, or a structure using a heat dissipating pipe. Furthermore, as described above, a heat sink may be provided via a heat radiating sheet or heat radiating grease, and a heat pipe may be connected to the heat sink, or a heat radiating fan may be provided on the heat sink to improve heat dissipation efficiency. .

The fan 6 is agitated by circulating the air in the housing 2 along a flow path as shown in FIG. 1, and includes a suction port 61 and a discharge port 62. The fan 6 is located between the pair of second heat sinks 5 </ b> A and 5 </ b> B and is supported by the upper surface of the housing 2 and the partition plate 9.
The dehumidifying agent 7 removes moisture in the housing 2. As this dehumidifier 7, silica gel etc. can be used, for example. The dehumidifying agent 7 is disposed on the suction port 61 side and the discharge port 62 side of the fan 6, and is attached on the partition plate 9. Note that the dehumidifying agent 7 loses its dehumidifying effect after a certain period of time, so that the lid of the housing 2 is removed and replaced as appropriate.

[Gas flow path in the housing]
Next, the gas flow path in the housing 2 will be described in more detail with reference to FIG. A white arrow in FIG. 1 indicates a gas flow path. In the present embodiment, the gas in the housing 2 is circulated counterclockwise. However, the present invention is not limited to this. For example, a configuration in which the inside of the housing 2 is circulated clockwise may be employed.
When the measuring instrument 1 is activated, power is supplied from the power source to the circuit board 31 and the fan 6 is driven.
And since the gas in the housing | casing 2 is sucked toward the suction inlet 61 of the fan 6 arrange | positioned in 2nd area | region SP2, the 2nd upstream of the arrangement | positioning arrange | positioned in the position facing the suction inlet 61 is carried out. The heat sink 5 </ b> A is traced and discharged toward the second heat sink 5 </ b> B on the downstream side disposed at a position facing the discharge port 62. At this time, the gas that has followed one of the second heat sinks 5A travels toward the second heat sink 5B on the downstream side while moisture is removed by the dehumidifying agent 7 along the partition plate 9 on which the fan 6 is supported. Flowing.
Next, since the gas that has traced the other second heat sink 5B is directed again to the suction port 61, it follows the lower side of the partition plate 9 to absorb the heat released from the first heat sink 4, It flows toward the second heat sink 5A on the upstream side.

According to the measuring instrument 1 of this embodiment mentioned above, there exist the following effects.
In the present embodiment, since the housing 2 has a sealed structure, external air does not enter the housing 2 and the humidity in the housing 2 is prevented from changing due to moisture contained in the external air. it can. Moreover, since the dehumidifying agent 7 is provided in the case 2 having a sealed structure, the humidity in the case 2 can be kept low by the dehumidifying agent 7. For this reason, the semiconductor element 32 of the measurement circuit 3 can be prevented from being affected by humidity, so that measurement errors can be prevented, and highly accurate measurement can be performed.
Furthermore, since the first heat sink 4 is disposed in close contact with the semiconductor element 32, the first heat sink 4 radiates heat generated from the semiconductor element 32 into the housing 2. The fan disposed in the housing 2 agitates the gas in the housing 2 and the second heat sink 5 disposed on the inner surface of the housing 2 heats the housing 2. The heat is transferred to the outer surface of the housing 2 and the heat is radiated from the outer surface of the housing 2 to the outside. Thereby, the temperature in the housing | casing 2 can be made uniform, suppressing the temperature rise in the housing | casing 2. FIG.
As described above, errors in measurement results due to temperature and humidity changes can be prevented, and the measurement accuracy of the measuring instrument 1 can be improved.

Moreover, the inside of the housing | casing 2 is divided into 1st area | region SP1 and 2nd area | region SP2 by the division board 9, and the gas in a housing | casing is circulated from 1st area | region SP1 to 2nd area | region SP2 with the fan 6. FIG. Since the flow path is formed, the temperature distribution in the housing 2 can be made more effective and uniform.
Further, the gas that has absorbed the heat released from the first heat sink 4 disposed in the first region SP1 flows toward the second heat sink 5 disposed in the second region SP2. Here, since the second heat sink 5 is disposed in the gas flow path in the housing 2, the heat of the gas flowing in from the first region SP1 is reliably absorbed by the second heat sink 5. To dissipate heat outside the housing. As described above, the temperature in the housing 2 can be made more effective and uniform, and the heat can be reliably radiated from the second heat sink 5 to the outside of the housing 2. Can be suppressed.

In addition, since a pair of the second heat sinks 5 are provided, the heat in the housing 2 can be efficiently radiated from the outside. The fan 6 is disposed in the second region SP2 and is attached to the partition plate 9. According to this, when the gas which followed one 2nd heat sink 5A passes the fan 6, since the division board 9 plays the role of a wall surface, it can prevent flowing out below the division board 9. FIG. And the flow path which makes gas go to the other 2nd heat sink 5B can be formed reliably, and the temperature in the housing | casing 2 can be made more uniform.
Furthermore, since argon gas whose specific gravity is larger than the specific gravity of air outside the housing 2 is sealed in the housing 2, the housing 2 moves from the outside of the housing 2 into the housing 2 due to the difference in specific gravity inside and outside the housing 2. Intrusion of air can be suppressed. Therefore, the humidity change of the gas in the housing | casing 2 can be suppressed more reliably.

Further, since the third heat sink 8 is provided on the outer surface of the housing 2, the third heat sink 8 efficiently externally transfers the heat in the housing 2 transferred to the outer surface of the housing 2 by the second heat sink 5. Can dissipate heat. Therefore, the temperature rise in the housing 2 can be further suppressed.
Further, since a pair of the dehumidifying agents 7 are disposed at positions sandwiching the fan 6, the gas that has traced the first region SP1 is dehydrated by the dehumidifying agent 7 disposed on the upstream side of the fan 6, The removed gas is discharged from the discharge port 62, and moisture is further removed by the dehumidifying agent 7 disposed on the downstream side of the fan 6. Therefore, since the dried gas flows from the second region SP2 to the first region SP1, the dried gas can always be flowed to the measurement circuit 3, and the error in the measurement result of the measurement circuit 3 caused by the humidity change can be further increased. It can be surely prevented.

[Modification of Embodiment]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
Here, FIG. 2 is a schematic diagram showing the inside of the measuring instrument 1 according to a modification of the embodiment.
As shown in FIG. 2, the optical measurement circuit 11 may be provided in the housing 2 of the measuring instrument 1 of the embodiment.
The light measurement circuit 11 transmits a photodiode 111 of a semiconductor element that operates as a photodetector, a circuit board 112 on which the photodiode 111 is mounted, a lens array 113 that transmits incident light from the outside, and the lens array 113. And an optical filter 114 that amplifies the frequency of incident light.
In this configuration as well, the humidity in the housing 2 can be kept low as in the above-described embodiment, so that the optical filter 114 that easily deteriorates due to humidity can be prevented from being deteriorated.
In addition to the optical filter 114, another optical component that is affected by changes in temperature and humidity may be provided.

In the embodiment, the partition plate 9 is disposed in the housing 2, but a configuration in which the partition plate 9 is not disposed may be employed. Also in this structure, the gas in the housing | casing 2 is stirred by the fan 6, and the temperature distribution in the housing | casing 2 can be made uniform.
In the embodiment, the third heat sink 8 is disposed on the outer surface of the housing 2, but the third heat sink 8 may not be disposed. In this case, the heat in the housing 2 is transmitted from the second heat sink 5 to the outer surface of the housing 2 and is radiated to the outside.

In the embodiment, the gap 10 is provided between the left and right end portions of the partition plate 9 and the wall surface of the housing 2. However, the opening portions are provided directly in the partition plate 9, and the left and right end portions of the partition plate 9 are provided. It is good also as a structure which supports a wall surface. Also with this configuration, the gas in the housing 2 can flow through the opening, and a gas flow path can be secured in the housing 2.
In the above embodiment, the fan 6 is disposed between the second heat sinks 5, but may be disposed in the vicinity of the measurement circuit 3. According to this configuration, the flow velocity of the gas in the vicinity of the measurement circuit 3 where the temperature is highest can be increased, and the heat of the first heat sink 4 can be efficiently radiated. Therefore, heat accumulation in the vicinity of the measurement circuit 3 can be more reliably prevented, and the influence of heat on the semiconductor element 32 can be more reliably reduced.

In the above embodiment, only one fan 6 is provided, but a plurality of fans 6 may be provided according to the space in the housing 2, and according to this configuration, the flow velocity of the gas flowing in the housing 2 The temperature distribution in the housing 2 can be made more uniform.
In the above-described embodiment, the dehumidifying agent 7 is disposed at a position sandwiching the fan 6. However, the present invention is not limited to this, and the dehumidifying agent 7 may be disposed at an arbitrary position in the gas flow path.

  DESCRIPTION OF SYMBOLS 1 ... Measuring device, 2 ... Housing | casing, 3 ... Measurement circuit, 4 ... 1st heat sink (1st heat radiating means), 5, 5A, 5B ... 2nd heat sink (2nd heat radiating means), 6 ... Fan , 7 ... Dehumidifying agent, 9 ... Partition plate, 10 ... Gap (opening), 32 ... Semiconductor element, SP1 ... First region, SP2 ... Second region.

Claims (4)

A housing having a built-in measurement circuit provided with a semiconductor element for performing measurement processing, and having a sealed structure;
A fan that stirs the gas in the housing;
A dehumidifying agent for removing moisture in the housing;
A first heat dissipating means disposed in close contact with the semiconductor element and dissipating heat of the semiconductor element into the housing;
A measuring instrument, comprising: a second heat dissipating means disposed on an inner surface of the housing and dissipating heat inside the housing to the outside of the housing. The measuring instrument according to claim 1, wherein
The housing is partitioned into a first region in which the first heat radiating means and the measurement circuit are disposed and a second region in which the second heat radiating means is disposed, and the measurement is performed. Comprising a partition plate provided facing the circuit;
A pair of openings are formed to communicate between the first region and the second region across the central portion of the partition plate facing the measurement circuit,
The fan forms a flow path that returns to the first region again through the first region, one of the pair of openings, the second region, and the other of the pair of openings,
The measuring device, wherein the second heat radiating means is disposed in the flow path of the gas flowing in the second region. The measuring instrument according to claim 2,
The fan is disposed in the second region;
At least one pair of the second heat dissipating means is disposed across the fan. The measuring instrument according to any one of claims 1 to 3,
A gas having a specific gravity greater than that of air outside the casing is enclosed in the casing.

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