JP5402839B2 - Electronic balance - Google Patents

Description

  The present invention relates to an electronic balance with a windshield case, and particularly to an electronic balance with a windshield that is low-cost, lightweight, and (reading 1 mg or less).

  Conventionally, in electronic balances with high accuracy and high resolution (reading of 1 mg or less), the external air flow has a great influence on the weighing accuracy. Therefore, a method of surrounding the weighing pan with a draft shield case to eliminate these error factors. Has been adopted. FIG. 7 is a top view (A) and a side view (B) showing an external appearance example of an electronic balance with a windshield case. As shown in the figure, the electronic balance 101 generally includes a lower case 102 that houses an electric circuit for measuring a sample weight, a display unit for displaying a measurement value, and the like, and an upper case 103 that is attached to the lower case 102. A windshield case 105 is disposed on 104 (see, for example, Patent Document 1).

  The windshield case 105 has a pair of L-shaped frames 106A and 106B erected on the upper case 103, a cylindrical structure 107 erected on the rear, and upper portions of the L-shaped frames 106A and 106B. A frame 109 composed of a four-sided frame screwed to the upper part of the cylindrical structure 107, a windshield 110 disposed on the front surface of the frame 109, and movable back and forth when an object is taken in and out The upper slide glass 111, the right slide glass 112, and the left slide glass 113 are included, and the weighing pan 114 is enclosed in a sealed state.

JP 2001-99699 A

  Conventionally, in the electronic balance, an aluminum alloy is often used as the material of the main body case 104, but recently, resin has been used as the material of the upper case 103 due to increasing needs for cost reduction and weight reduction. Yes. When the material of the main body case 104 is a metal material such as an aluminum alloy, the main body case 104 and the cylindrical structure are electrically connected, so the influence on the measurement accuracy of external electromagnetic waves and static electricity is small. Although it can be ignored, when the upper case 103 is made of resin, there is a problem that the measurement accuracy is greatly affected by the intrusion of electromagnetic waves from the outside and the generation of static electricity.

  Further, when the upper case 103 is made of resin, it is easily deformed due to the influence of aging and environmental conditions, and when the upper case 103 around the lower portion of the cylindrical structure 107 shown in FIG. The body 107 may tilt backward. When the tubular structure 107 is tilted rearward, the front of the frame body 109 is lifted, and a gap is formed between the upper portion of the windshield 110 and the frame body 109, and the sealing performance of the windshield case is destroyed, which affects the measurement accuracy and the windshield. There is a problem that rattling occurs. Further, since the casing is made of resin, insufficient rigidity becomes a problem.

  The electronic balance according to the present invention is provided with a lower case made of metal and an upper case made of resin, a load detection unit for detecting the load of an object to be measured, and a windshield provided on the load detection unit and the main body case. An electronic balance for placing an object to be weighed on a weighing pan in a windshield case and weighing the weight thereof, and a metal tubular structure constituting a rear wall of the windshield case, and the tubular shape A conductive structure that electrically connects the structure and the lower case is provided.

Furthermore, a metal plate disposed on the upper surface of the upper case in the windshield case and a metal member for connecting the metal plate and the cylindrical structure are provided.
Furthermore, the conductive structure has a vertical reinforcing portion that prevents the upper case from being deformed.

  Since the electronic balance includes a conductive structure for conducting the lower case and the cylindrical structure, and a metal member for conducting the cylindrical structure and the metal plate on the upper surface of the upper case in the windshield case, the electromagnetic balance from the outside Since the static electricity passes through the outer shell of the main body case of the electronic balance from the cylindrical structure through the conductive structure and the metal member, interference with the internal electric circuit is eliminated. Further, since the conductive structure has a vertical reinforcing portion that prevents the upper case from being deformed, it is possible to prevent the windshield case from being lifted in front of the upper part. As a result, a low-cost, lightweight and highly accurate electronic balance with a windshield can be obtained while preventing insufficient strength.

1A and 1B are a central cross-sectional view (A) and a cross-sectional view A-A (B) showing a configuration of a housing of an electronic balance according to the present invention. It is the top view (A) and right view (B) of the bracket which concern on an Example. It is the top view (A) and right view (B) of the bracket which concern on an Example. It is the back view (A) of the cover by other Examples, its BB sectional drawing (B), and CC sectional drawing (C). It is the top view (A) and right view (B) of the bracket which concern on an Example. It is the top view (A) and right view (B) of the bracket which concern on an Example. They are a top view (A) and a right side view (B) of a conventional electronic balance with a windshield case.

  Embodiments of an electronic balance according to the present invention will be described below with reference to the drawings. FIG. 1 is a central sectional view (A) and a sectional view A-A (B) in the front-rear direction of the casing of the electronic balance of the present invention. 2 and 3 are a top view (A) and a right side view (B) of the brackets 16 and 17 according to the embodiment. The housing 1 forms a storage chamber 2a that stores a load detection unit that detects the load of the object to be weighed and an electric circuit that converts an electric signal detected from the load detection unit into weight value data of the object to be weighed. A main body case 6 composed of a lower case 2 made of metal and a resin upper case 5 and the like, which are attached to the lower case 2 and joined by two screws 3 and 4 respectively, are disposed on the upper surface thereof. The windshield case 7 is configured.

  The windshield case 7 includes a pair of L-shaped frames 8A and 8B standing at both ends of a groove 5a provided in the upper case 5, a pair of mold members 91 and 92 and metal plates 93 and 94 standing rearward. A cylindrical structure 9 having a housing chamber 9a surrounded by a four-side frame attached to the heads of the L-shaped frames 8A and 8B and fastened to the heads of the mold members 91 and 92 with screws 10 A frame 11 is configured. A windshield 12 is fitted to the frame, and a right slide glass 13, a left slide glass 14, and an upper slide glass 15 are fitted so as to be movable back and forth.

  Brackets 16 and 17 as a pair of metal conductive structures shown in FIGS. 2 and 3 are disposed on the back surface of the upper case 5. Small holes 16 a and 16 b are formed in the bracket 16, and small holes 17 a and 17 b are formed in the bracket 17. As shown in FIG. 1, the bracket 16 is connected to the cast member 91 via the upper case 5 by screws 18 that pass through the small holes 16 a, and the rear part abuts against the lower case 2, and the upper case 5 is connected to the lower case 2 by screws 4. They are connected together. Thereby, the cylindrical structure 9 is electrically connected to the lower case 2 electrically. Similarly, the mold member 92 is electrically connected to the lower case 2 by the bracket 17.

  Further, the metal plate 19 attached to the upper surface of the upper case 5 in the windshield case 7 contacts the metal member 20 fixed to the metal plate 93, and the metal plate 19 and the lower case 2 are electrically connected. Yes.

  A metal plate 21 is attached to the upper surface of the storage chamber 2a of the lower case 2 in a conductive state, and the storage chamber 2a is electrically shielded. The accommodating chamber 9a in the cylindrical structure 9 accommodates a substrate for measurement, but is electrically connected to the accommodating chamber 2a. Therefore, external radio noise is generated from the cylindrical structure 9 and the lower case 2. Interference with the internal electric circuit is prevented by passing through. Further, since the metal plate 19 is also electrically connected to the lower case 2, the influence of the measured value of static electricity induced on the metal plate 19 is prevented. Note that an interface circuit with a power source circuit or an external device may be disposed in the storage chamber 9a.

  Another embodiment of the upper case 5 used for the main body case 6 will be described with reference to FIGS. 4, 5 and 6. FIG. 4 is a rear view (A), a BB sectional view (B) and a CC sectional view (C) of the upper case 5A according to another embodiment, and FIGS. 5 and 6 are a bracket 22 and a bracket 23 according to the embodiment. It is each top view (A) and right side view (B).

  The brackets 22 and 23 are provided with vertical reinforcement portions 22a and 22b and vertical reinforcement portions 23a and 23b, which are perpendicular to the back surface of the upper case 5A, to the brackets 16 and 17, so that the load due to deformation of the windshield case 7 and the upper case 5A This is an improvement in the vertical prevention strength. Further, the upper case 5A is provided with a protruding portion 5b and a protruding portion 5c in which a recess for fitting one end of the bracket 22 and the bracket 23 is formed at a symmetrical position.

  By fixing the mold member 91 to the upper case 5A with the screw 18 with one end of the bracket 22 inserted into the recess of the protrusion 5b of the upper case 5A, the upper case on the protrusion 5b with respect to the fixing portion of the mold member 91 is secured. Displacement in the vertical direction of the part of 5A is suppressed. Further, the mold member 92 is fixed by the screw 18 via the upper case 5A in a state where one end of the bracket 23 is inserted into the recess of the protruding portion 5c. Accordingly, the periphery of the mold members 91 and 92 of the upper case 5A is reinforced by the vertical reinforcement portions 22a and 22b of the bracket 22 and the vertical reinforcement portions 23a and 23b of the bracket 23, and the inclination factor of the mold members 91 and 92 is removed.

  In addition, this invention is not limited to the said Example, For example, as a fixing method of the said brackets 22 and 23, small holes 22c and 23c are opened as shown in FIG.5, FIG.6, and the screw 24 is used as shown in FIG. You may screw to upper case 5A. One end of the bracket 22 may be embedded in the upper case in advance.

  Low cost, lightweight and high precision electronic balance with draft shield.

DESCRIPTION OF SYMBOLS 1 Housing | casing 2 Lower case 2a Accommodating chamber 3 Screw 4 Screw 5 Upper case 5A Upper case 5a Groove 5b Protruding portion 5c Protruding portion 6 Main body case 7 Windshield case 8A L-shaped frame 8B L-shaped frame 9 Cylindrical structure 9a Accommodating chamber DESCRIPTION OF SYMBOLS 10 Screw 11 Frame 12 Front glass 13 Right slide glass 14 Left slide glass 15 Upper slide glass 16 Bracket 16a Small hole 16b Small hole 17 Bracket 17a Small hole 17b Small hole 18 Screw 19 Metal plate 20 Metal member 21 Metal plate 22 Bracket 22a Vertical reinforcement part 22b Vertical reinforcement part 22c Small hole 23 Bracket 23a Vertical reinforcement part 23b Vertical reinforcement part 23c Small hole 24 Screw 91 Mold member 92 Mold member 93 Metal plate 94 Metal plate 101 Electronic balance 102 Lower case 10 3 Upper case 104 Main body case 105 Windshield case 106A L-shaped frame 106B L-shaped frame 107 Cylindrical structure 109 Frame 110 Front glass 111 Upper slide glass 112 Right slide glass 113 Left slide glass 114 Weighing pan

Claims (3)

  A metal lower case and a resin upper case are provided, and a load detection unit for detecting the load of the object to be weighed and a windshield case provided on the main body case are provided on the weighing pan in the windshield case. In an electronic balance on which an object to be weighed is placed and weighed, a metal cylindrical structure constituting a rear wall of the windshield case, and the cylindrical structure and a lower case are electrically connected to each other. An electronic balance comprising a conductive structure.   2. The electronic balance according to claim 1, further comprising: a metal plate disposed on an upper surface of the upper case in the windshield case; and a metal member that connects the metal plate and the cylindrical structure.   3. The electronic balance according to claim 1, wherein the conductive structure has a reinforcing portion that prevents deformation of the upper case.

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