JP3922328B2 - Electronic balance - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic balance, and more particularly, to an electronic balance that includes a weighing chamber that accommodates a weighing pan and includes a balance mechanism directly below the weighing pan.
[0002]
[Prior art]
In an electronic balance in which a balance mechanism is arranged immediately below the weighing pan and is provided with a weighing chamber, a through hole is formed in the ceiling surface of the casing that houses the balance mechanism, and the weighing pan that is engaged with the balance mechanism is A weighing chamber is provided on the casing so as to surround the weighing pan, and is disposed on the top of the tray receiving rod extending upward through the through hole.
[0003]
By the way, in this type of electronic balance, the elements in the circuit generate heat by energizing the electric circuit such as the power supply circuit unit and drive control, and when this electric circuit is housed in the same casing as the balance mechanism, The temperature inside the casing rises and the temperature difference from the weighing chamber provided above the casing increases. This increase in temperature difference leads to generation of an air flow from the inside of the casing to the weighing chamber through a through hole for taking out the weighing dish formed on the upper surface of the casing. This airflow hits the back surface of the weighing pan placed immediately above the through hole, causing the measurement display value to fluctuate and causing the value to include an error.
[0004]
Conventionally, by accommodating the electrical circuit in a casing different from the casing housing the balance mechanism, it is possible to suppress the heat generated by the electrical circuit element from reaching the casing housing the balance mechanism. Measures for reducing the temperature difference between the balance mechanism casing and the weighing chamber as much as possible, or, as shown in the cross-sectional view of the main part in FIG. 2, formed on the upper surface of the casing 201 that houses the balance mechanism and the electric circuit. A windbreak plate 203 is provided above the through hole 202, and when the air heated by the heat generated by the electric circuit element in the casing 201 flows into the weighing chamber 204 through the through hole 202, most of the airflow passes therethrough. A measure or the like is adopted that is guided around the hole 202 so as not to hit the weighing pan 205 directly.
[0005]
[Problems to be solved by the invention]
By the way, of the above conventional measures, the measure for housing the electric circuit in a casing different from the balance mechanism has a problem that a separate dedicated casing is required and the cost is increased, and the windshield is also provided. In order to make the windshield plate function effectively, it is necessary to increase the distance between the upper surface of the casing and the windshield plate, and accordingly, the installation height of the weighing pan increases. In addition to being unpreferable in terms of design, there are cases where operability in a weighing operation or the like deteriorates.
[0006]
The present invention has been made in view of such circumstances, and can suppress fluctuations in measurement values due to heat generation of the electric circuit board without significantly increasing the cost and without impairing the design and operability. The purpose is to provide electronic balances.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the electronic balance of the present invention has a balance mechanism directly under the weighing pan, and the balance mechanism is housed in the same casing as the electric circuit of the electronic balance, and is placed on the casing. An electronic balance provided with a weighing chamber containing a weighing pan taken out of the casing through a through-hole formed in the ceiling surface of the casing, wherein the through-hole and the balance mechanism are provided inside the casing. A region including the power circuit portion of the electric circuit, and a region including other circuit portions other than the power circuit portion are separated from each other by an airflow blocking member, and the casing together in a region where the power supply circuit portion of the are arranged are formed opening for releasing hot air to the outside, the through holes and the balance mechanism Other arrangement region of the circuit portion between the arrangement region of free space and the power supply circuit portion is characterized by being interposed (claim 1).
[0008]
The present invention accommodates the electric circuit in the same casing as the balance mechanism, but does not allow the heat generated by the heat generated by the elements in the electric circuit , particularly the heat generated in the power circuit section, to flow into the balance mechanism and the through hole side, It aims to achieve its intended purpose by letting it directly to the outside.
[0009]
Ie upon the casing, a region including the balance mechanism including a through-hole, the arrangement region of the power source circuit section, a partition and a placement region of the other circuit portion except for the power supply circuit unit in each air flow blockage member, An open part for releasing hot air to the outside is formed in the arrangement area of the power circuit section, and further, the arrangement area of other circuit sections between the arrangement area of the power circuit section and the area including the through hole and the balance mechanism By adopting the configuration that intervenes, the heat generated in the power supply circuit section with the largest amount of heat is released directly to the outside, and the area including the through hole and the balance mechanism is different from the arrangement area of other circuit sections. The air flow blocking member between the other circuit portion and the air flow blocking member between the arrangement region of the other circuit portion and the power supply circuit portion are arranged in the power supply circuit portion and the open portion by the double air flow blocking member. Power supply circuit section because it is partitioned against In addition, the air flow generated in the casing due to heat generation in the other circuit part reaches the placement area of the balance mechanism, and the outside air flowing into the casing through the opening part reaches the placement area of the balance mechanism. It can be surely prevented. As a result, the difference between the temperature in the region where the balance mechanism is arranged and the through-hole communicating with the weighing chamber is formed and the temperature in the weighing chamber is reduced, and flows into the weighing chamber through the through-hole. In addition to suppressing the generation of airflow, the outside air flowing into the casing through the open part is also prevented from reaching the balance mechanism placement area by the double airflow blocking member, and fluctuations in the weighing display value are prevented. It does not occur.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a configuration of an embodiment of the present invention. In FIG. 1, illustrations of wirings connecting the respective parts are omitted.
[0011]
The balance mechanism 1 is housed in the same casing 3 including a balance base 31 and a balance case 32 covering the balance base 31 together with an electric circuit including a power supply circuit unit 21, a control circuit board 22 and a display circuit board 23. . The balance case 32 is fixed to the balance base 31, and a substantially constant gap G is formed between the balance case 32 and the balance case 32. A display 4 for displaying a measured value or the like is attached to one end of the balance case 32.
[0012]
The balance mechanism 1 is provided with a pan receiving rod 11 for supporting the weighing pan 5. The pan receiving rod 11 is attached to the outside of the casing 3 through a through hole 32 b formed in the top surface 32 a of the balance case 32. The weighing pan 5 is placed on the tip of the weighing pan 5 and is disposed above the outside of the casing 3. The weighing pan 5 is accommodated in a weighing chamber 6 provided on the casing 3. The weighing chamber 6 is provided with doors 6a provided on the ceiling portion thereof and doors (not shown) provided on both side walls, and these doors are used for loading the sample to be measured on the weighing pan 5. Done by opening. In FIG. 1, reference numeral 61 denotes a wall supporting member including doors of the weighing chamber 6. The upper edge of the supporting member 61 passes through the end when the ceiling door 6 a is opened. The slit 61a for making it form is formed.
[0013]
The balance mechanism 1 is housed in the casing 3 in a state of being housed in the inner case 7. The inner case 7 has a through-hole 7 a for allowing the pan support rod 11 to pass therethrough, and is used for adjusting the four corner errors of the balance mechanism 1. Holes 7b are formed, and besides these holes, wiring holes (not shown) for connecting the balance mechanism 1 and the control substrate 22 are formed, and the plurality of holes are connected to other regions in the casing 3. Communicate.
[0014]
Of the electric circuits described above, the display circuit board 23 is disposed on one end side in the casing 3 in the vicinity of the display 4, and the power supply circuit unit 21 is disposed on the other end side of the casing 3. A control circuit board 22 is disposed between the power supply circuit unit 21 and the inner case 7 housing the balance mechanism 1. An air flow blocking member 81 whose tip reaches the ceiling surface 32 a of the balance case 32 is provided at the periphery of the ceiling surface 7 c of the inner case 7, and between the power supply circuit unit 21 and the control circuit board 22. Also, air flow blocking members 82 and 83 are provided between the inner case 7 and the display circuit board 23, respectively. Each air flow blocking member 81, 82, 83 is a flat plate member in this example, and any material such as resin, metal, etc. can be adopted as the material, and the inside of the casing 3 is each of these air The flow blocking members 81, 82, and 83 are substantially divided into four regions. In addition, the wiring between each area | region is performed through the hole for wiring (not shown) formed in each airflow interruption | blocking member 81,82,83.
[0015]
The ceiling surface 32 a of the balance case 32 is formed with an open portion 32 c for releasing hot air to the outside in the region where the power supply circuit portion 21 is accommodated. The open portion 32 c is the upper edge of the support member 61 of the weighing chamber 6. It communicates with the outside through a slit 61a provided in the section.
[0016]
In the above embodiment, power is supplied to the control circuit board 22 and the display circuit board 23 by energization of the power supply circuit unit 21, and the operation state is brought about. In particular, the amount of heat generated in the power supply circuit unit 21 becomes large. The surrounding air is heated by the heat generated in the power supply circuit 21, and the hot air mainly generates an upward air flow, but the hot air enters the arrangement area of the control circuit board 22 due to the presence of the air flow blocking member 82. Most of them escape to the outside of the casing 3 without forming convection in the casing 3 through the open portion 32c formed on the ceiling surface 32a of the balance case 32, and further to the outside through the slit 61a. Released. Further, even when outside air flows into the open portion 32 c of the casing 3 through the slit 61 a, the air flow is suppressed from flowing into the arrangement region of the adjacent control circuit board 22 by the air flow blocking member 82. In addition, even if the air flow blocking member 82 has a gap such as a wiring hole for connecting between the power supply circuit unit 21 and the control circuit board 22, the control circuit board 22 slightly passes through the gap. The air flow reaching the arrangement area is prevented from reaching the arrangement area of the balance mechanism 1 by the air flow blocking member 81.
[0017]
On the other hand, the air flow equivalent to the above due to the heat generated in the control circuit board 22 is prevented from entering the placement area of the balance mechanism 1 due to the presence of the air flow blocking member 81, and further, The airflow generated by heat generation is also prevented from entering the arrangement area of the balance mechanism 1 due to the presence of the airflow blocking members 83 and 81. The hot air generated by the heat generated by the control circuit board 22 and the display circuit board 23 is discharged to the outside of the casing 3 through a gap G formed between the balance base 31 and the balance case 32. There is no jealousy.
[0018]
As a result, the temperature of the arrangement region of the balance mechanism 1 is not easily affected by the heat generated by the elements in the power supply circuit unit 21, the control circuit board 22, and the display circuit board 23, and the inflow of airflow hardly occurs. Thereby, the air current flowing into the weighing chamber 6 through the through hole 32b is not generated, and the measurement display value does not fluctuate.
[0019]
【The invention's effect】
As described above, according to the present invention, accommodates the balance mechanism and the electric circuits in the same casing, the arrangement region of the balance mechanism, the arrangement region of the power source circuit portion of the electric circuit, the power supply a placement region of the other circuit portion except for the circuit portions, each partition by the air flow blocking member, an opening communicating with the outside is provided on the distribution depositing area of the casing of the power supply circuit unit, moreover, the power supply circuit section and the balance mechanism Since the arrangement area of the other electric circuit is interposed between the arrangement area of the electric circuit and the hot air generated in the power supply circuit section having the largest heat generation amount flows into the arrangement area of the other circuit section and the arrangement area of the balance mechanism. is directly discharged to the outside through the opening portion without, and, for the outside air flowing into the casing through the opening portion of the casing, the presence of the air flow blocking member to the arrangement region of the balance mechanism It is prevented from reaching. Moreover, the arrangement area of the balance mechanism is partitioned from the power supply circuit part and the open part by the double air flow blocking member, and the effect of blocking the hot air generated in the power supply circuit part on the arrangement area of the balance mechanism, and The blocking effect of the outside air flowing in through the opening portion on the arrangement area of the balance mechanism is ensured. As a result, without providing a casing for electric times Michi専 and without increasing the height from the casing top surface to the weighing dish provided windbreak plate, therefore without increasing the cost, and design Without impairing the operability, it is possible to suppress the generation of the airflow flowing into the weighing chamber through the through hole for taking out the dish on the ceiling surface of the casing, and to prevent the measurement display value from fluctuating.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a configuration of an embodiment of the present invention.
FIG. 2 is an explanatory view of a conventional countermeasure using a windshield plate for suppressing fluctuation of a measurement display value due to an airflow flowing from a casing into a weighing chamber through a through hole.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Balance mechanism 11 Countersink 21 Power supply circuit part 22 Control circuit board 23 Display circuit board 3 Casing 31 Balance base 32 Balance case 32a Ceiling surface 32b Through-hole 32c Open part 4 Display 5 Weighing pan 6 Weighing chamber 7 Inner case 81, 82, 83 Air flow blocking member G Gap

Claims (1)

A balance mechanism is provided directly under the weighing pan, and the balance mechanism is accommodated in the same casing as the electric circuit of the electronic balance. On the casing, through a through hole formed in the ceiling surface of the casing. in electronic balance weighing chamber are thus provided which encloses the weighing pan, which is taken out outside the casing upwards, inside the casing, a region including the through hole and the balance mechanism, the power supply circuit portion of the electric circuit is arranged and regions, and other circuitry are disposed region except the power supply circuit portion is separated from each other by the air flow blocking member respectively, and, in a region where the power supply circuit portion of the casing are disposed hot air together are formed opening for releasing to the outside, and other times between regions and arrangement region of the power supply circuit section including the through holes and the balance mechanism Electronic balance arrangement region parts is characterized in that interposed.

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