JP2002267364A - Low humidity chamber with hygrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that, in a conventional low humidity chamber with a hygrometer, since a battery is increased in size, the size of whole is increased, there is a defect that handling, mounting and demounting thereof are difficult to make, and humidity display is unclear. SOLUTION: In the low humidity chamber with a hygrometer, an electrostatic capacity type hygrometer where a battery and a humidity sensor to effect intermittent measurement of humidity are integrally mounted, and a drying unit for removing humidity are situated in the low humidity chamber having a glass door, a humidity display panel of the electrostatic capacity type hygrometer is removably mounted in the low humidity chamber by a mounting means such that the humidity display panel of the electrostatic capacity type hygrometer is opposed to the inner surface of a glass door. The humidity panel continuously displays humidity in a digital value and when a battery voltage is reduced to 60% or less, the humidity display panel is flickered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low humidity chamber equipped with a hygrometer, and more particularly to a low humidity chamber having a capacitance type hygrometer.

[0002]

2. Description of the Related Art An IC package used for general electronic equipment, when placed in the air, tends to adsorb moisture in the air.
When soldering an IC package that has absorbed a certain amount of water or more, the water accumulated in the IC package expands instantaneously due to the heat of the reflow and destroys the IC package. To prevent this, the IC package is shipped sealed in an aluminum pack with a desiccant and humidity indicator card. This humidity indicator card is for confirming whether or not the inside of the aluminum pack was low in humidity.

[0003] After opening this IC package, the IC package is mounted on a mounting machine and mounted on a printed circuit board. The resulting IC package is stored in a low-humidity container having a humidity of 5% RH or less to prevent moisture from entering the IC package. are doing.

A sensor using an electric resistance method for the sensor of this hygrometer is known. This resistance digital hygrometer utilizes the fact that the impedance of the sensor element changes depending on the amount of moisture in the moisture sensitive material. That is, in the sensor section, the + and-electrodes are arranged in parallel on the polymer moisture-sensitive material, and the impedance change between the two electrodes due to the moisture content due to the increase and decrease of the humidity is taken out as a voltage conversion circuit output (VS). Since this output is an analog value, it is subjected to A / D conversion via a voltmeter IC, sent to the display unit, and converted into a digital value as humidity 5% RH to 100% RH.
Display up to.

[0005] On the other hand, a capacitance-type hygrometer capable of measuring low humidity up to 1% RH is also known. As shown in FIG. 6, the capacitance type digital hygrometer utilizes a change in capacitance (C) due to a change in humidity. A change in capacitance due to the moisture content of the moisture-sensitive film is taken out as a change in the frequency (F) of the oscillation circuit 2, and the frequency change is converted into a voltage change by the frequency / voltage conversion circuit 3 and output (VS). I do. And A
The analog voltage (VS) obtained by A / D conversion by the microcontroller 4 including the / D converter is corrected and sent to the display unit 5 to display the humidity from 1% RH to 100% RH as a digital value. Unlike the resistance method, the capacitance method converts the capacitance that changes with humidity into frequency, so the change in this value is a change in the primary ratio compared to the change in the exponential function of the resistance method. It can also be measured with humidity.

For the purpose of the above correction, since the humidity sensor has a unique non-linear portion, the value of the non-linear portion is converted into a numerical value in order to convert the non-linear portion into a straight line, and the numerical value is taken into a microcontroller to make a straight line. .

As external outputs, digital outputs RS-232 and 1
Two types of output, analog output at 0 mV /%, are obtained.
Digital output RS-232 can be directly input to the computer,
On the other hand, the analog output can be used as an input for a data logger or the like for storing humidity data. Reference numeral 6 denotes a power supply using a battery.

[0008] The reason why such external output is required is that when managing the IC package in a low humidity chamber, it is most important to determine what% RH the humidity was at the time of management, and directly to the personal computer by RS-232 output. Take in the data and save it,
Once data is imported into the data logger, this data is input to a personal computer and saved, and if a failure occurs in the IC package, it is to confirm whether the humidity in the low humidity storage was normal. .

[0009]

However, since the above-mentioned electric resistance value changes exponentially with respect to humidity,
At 5% RH or less, it is difficult to detect the humidity at 5% or less because of high resistance.

In addition, the capacitance type digital hygrometer consumes much electric power as compared with the conventional resistance type digital hygrometer because a conversion circuit for extracting an electric signal from a sensor is complicated. For example, when the humidity is 5% RH, the power consumption is about 400 μA at a voltage of DC 5 V, and the power consumption is about seven times that of the resistance type.

Further, in the conventional display of humidity, a decimal point is also displayed to improve accuracy. However, when used in a low-humidity chamber, the numerical value is viewed at a certain distance, so that the decimal point is not known. Sometimes mistaken for% RH.

Further, since a battery is used as a power source, the size of the battery becomes large, and it becomes an obstacle when the IC package is stored in the storage.
Also, this hygrometer shows the correct value for six months or
In order to remove and calibrate once a year, it is important that they are compact and easy to install and remove, but as described above, they are large and difficult to install and remove.
If an external power supply is used instead of a battery, if it is mounted on the front glass (inside the cabinet) or near the shelf, wiring for power input will be a hindrance when inserting or removing the IC package. .

Further, when selling overseas, the voltage differs for each country, so it is necessary to handle the voltage, so that the battery type must be used.

An object of the present invention is to provide a low-humidity storage with a hygrometer that eliminates the above-mentioned disadvantages.

[0015]

A low humidity chamber with a hygrometer according to the present invention comprises a capacitance type hygrometer containing a battery and a humidity sensor for intermittently measuring humidity, and a drying unit for removing moisture. And a glass door, wherein the capacitance-type hygrometer is detachably mounted in the low-humidity chamber by mounting means so that the humidity display panel faces the inner surface of the glass door. I do.

Further, the low humidity chamber with a hygrometer of the present invention is characterized in that the humidity display panel continuously displays the humidity as a digital value.

Further, the low humidity chamber with a hygrometer according to the present invention is characterized in that the humidity display panel blinks when the battery voltage drops to 60% or less.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a hygrometer 7 and a fixture 8 in the low humidity chamber with a hygrometer of the present invention, and FIGS. 2 and 3 show a low humidity chamber 9 to which these are attached.

2 and 3, 10 is a low humidity cabinet, 11 is a drying unit for removing moisture, 12 is a caster, 13 is a shelf board, and 14 is placed on the shelf board 13.
IC package, 15 is a glass door, 16 is its handle, 17
Is the glass surface.

In FIG. 1, reference numeral 18 denotes a hygrometer case,
Reference numeral 19 denotes a humidity sensor partially exposed at the top of the case 18, reference numeral 20 denotes a power switch, reference numeral 21 denotes a humidity display panel, and reference numeral 22 denotes an external output terminal.

In the present invention, the fixture 8 is attached to the hygrometer 7, and the fixture 8 is attached to the inner surface of the cabinet 10 or the inner surface of the glass door 15 by attaching screws or the like. Is opposed to the inner surface of the glass surface 17.

In another embodiment of the present invention, as shown in FIGS. 4 and 5, a holder 23 for inserting a hygrometer having an open upper surface inside the glass surface 17 is attached.
Insert the hygrometer 7 inside.

The hygrometer 7 may be placed directly on the shelf 13 as long as the humidity display panel 21 can be placed close to the inner surface of the glass surface 17.

The drying unit 11 of such a low-humidity storage is provided.
In, the desiccant is regenerated by a heater for a certain period of time, the shutter is switched between the inside and outside of the refrigerator during the regeneration, the desiccant releases moisture adsorbed from the inside of the refrigerator to the outside, and when the regeneration is over, the shutter is switched, Adsorption of moisture in the refrigerator is started, and thereafter, this cycle is repeated.

In general regeneration, a desiccant is added at about 150 ° C. for about 30 minutes.
Heating for a minute, this regeneration is repeated about every 6 hours, and these operations are performed by a timer. Since the desiccant is automatically regenerated regularly as described above, the humidity in the low humidity chamber can be reduced to 1% RH.

Since the humidity change in the low humidity chamber is gradual except when the door is opened and closed, in the low humidity chamber with the hygrometer of the present invention, the humidity is measured by the microcontroller 4 in order to reduce the power consumption of the hygrometer 7. For example, the measurement is performed intermittently, for example, once every 20 seconds to 30 seconds, and the measurement is performed for about 1 second. During times other than the fixed time, the timer is left, the external output and the display unit are left, and the sleep mode is set. In this way, the size of the battery can be reduced, and the life thereof can be greatly extended.

The value of the humidity is digitally displayed continuously on the humidity display panel. Furthermore, if the battery is used for more than one year, the battery will be exhausted, so it is displayed that the battery has run out. Generally, when the power supply voltage falls below 60%, the humidity display is not accurate. Therefore, the voltage of the battery is constantly measured, and this value is input to the microcontroller 4.
When the voltage drops below 60%, for example, from 6V to 3.6V, the display value of humidity blinks to notify the battery life.

[0029]

As described above, according to the low humidity chamber with a hygrometer of the present invention, the hygrometer for the low humidity chamber is small in size and can be easily attached and removed, and its display can be easily judged through the glass surface of the door. Also, there are great benefits such as a longer battery life.

[Brief description of the drawings]

FIG. 1 is a perspective view for explaining a hygrometer of a low humidity chamber with a hygrometer of the present invention.

FIG. 2 is a side view of the low humidity storage with a hygrometer of the present invention.

FIG. 3 is a front view of a low humidity storage with a hygrometer of the present invention.

FIG. 4 is a front view of a main part showing another embodiment of the low humidity chamber with a hygrometer of the present invention.

FIG. 5 is a side view of a main part of the low humidity chamber shown in FIG.

FIG. 6 is an explanatory diagram of a capacitance type digital hygrometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor part 2 Oscillation circuit 3 Frequency / voltage conversion circuit 4 Microcontroller 5 Display part 6 Power supply 7 Hygrometer 8 Fixture 9 Low humidity storage 10 Cabinet 11 Drying unit 12 Caster 13 Shelf board 14 IC package 15 Glass door 16 Handle 17 Glass surface 18 Hygrometer case 19 Humidity sensor 20 Power switch 21 Humidity display panel 22 External output terminal 23 Holder

Claims (3)

[Claims] 1. A capacitance type hygrometer including a battery and a humidity sensor for intermittently measuring humidity, a drying unit for removing moisture, and a glass door. A low humidity chamber with a hygrometer, wherein the humidity meter is detachably mounted in the low humidity chamber by mounting means so that the humidity display panel faces the inner surface of the glass door. 2. The low humidity storage with a hygrometer according to claim 1, wherein the humidity display panel displays the humidity continuously in a digital value. 3. The low humidity storage with a hygrometer according to claim 1, wherein the humidity display panel blinks when the battery voltage drops to 60% or less.