Precision scale having a removable climate module

Abstract

A precision balance including a weighing chamber (16); a draft shield (18, 20, 22), which surrounds the weighing chamber (16); a climate module (34), which is detachably disposed in the weighing chamber (16); a processor (32) and a data input unit, which both form part of the overall precision balance; and a data transmission path, over which data is exchanged between the climate module (34) and the processor (32). Also disclosed is a climate module for a precision balance. The climate module (34) forms a self-contained modular unit and includes an air pressure sensor (62), an air humidity sensor (54) and an air temperature sensor (52) The climate module also includes a data transmission path configured to transmit data to a processor external to the climate module, and a mounting mechanism configured to secure the climate module detachably to a weighing module (10).

Claims

1. Precision balance, comprising: a weighing chamber; a draft shield, which surrounds the weighing chamber and which comprises a mechanically resilient shield coupling part; a climate module, which comprises an air pressure sensor, an air humidity sensor and an air temperature sensor, and which further comprises a mechanically resilient module coupling part configured complementary to the shield coupling part, wherein the climate module is configured to be mounted and dismounted in the weighing chamber by attaching to and detaching from the draft shield via the coupling parts; a processor; a data input unit; and a data transmission path, over which data is exchanged between the climate module and the processor.

2. The precision balance as claimed in claim 1, wherein the data transmission path comprises an electrical plug-in connection.

3. The precision balance as claimed in claim 1, wherein the data transmission path comprises a wireless transmission.

4. The precision balance as claimed in claim 1, wherein the climate module further comprises a sensor coupled to the data transmission path and configured to determine a degree of ionization in the weighing chamber.

5. The precision balance as claimed in claim 1, wherein the climate module comprises a light sensor, which is coupled to the data transmission path.

6. The precision balance as claimed in claim 1, wherein the processor is programmed to determine, based on a density of a substance to be weighed, an air buoyancy of a test sample or a buoyancy correction factor from the air pressure, the air humidity and the air temperature in the weighing chamber.

7. The precision balance as claimed in claim 1, wherein the shield coupling part comprises at least one slot in a wall of the draft shield and the module coupling part comprises at least one locking protrusion.

8. The precision balance as claimed in claim 7, wherein the shield coupling part comprises at least two mutually spaced slots in the wall of the draft shield and the module coupling part comprises at least two mutually spaced locking tabs configured to insert respectively into the at least two slots.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Additional features and advantages of the invention will become apparent from the following description and from the following drawings, to which reference is made. The drawings show in:

(2) FIG. 1 an exploded view of a precision balance, according to the invention,

(3) FIG. 2 a perspective view of an inventive climate module, which can be used in the precision balance of the invention,

(4) FIG. 3 a side view of the climate module from FIG. 2 without the outer housing, and

(5) FIG. 4 a plan view of the climate module from FIG. 2, also without the outer housing.

DETAILED DESCRIPTION

(6) FIG. 1 shows a high resolution electronic balance (precision balance) that in this exemplary embodiment permits mass comparisons to be performed for the accuracy classes E1-F2 in compliance with OIML R 111-1.

(7) However, the invention relates, in general, to any high resolution electronic balance of high accuracy, i.e., with a measuring resolution in the range of micrograms down to nanograms.

(8) The precision balance comprises a load cell 14 with a base 12. In addition, the load cell 14 comprises a weighing chamber 16, which is formed by a draft shield with adjustable side walls 18, a front wall 20 and a rear wall 22. The weighing chamber 16 is separated from the surrounding area by the draft shield. A weighing dish 24 is used to hold the sample to be weighed. These components together form a weighing module 10.

(9) An electronic evaluation system 26, which is designed as a separate part in this embodiment, is electronically coupled to the load cell 14 via a cable 28. A display unit 30, which is coupled to the evaluation system 26, is used both as a display and as a data input unit. While the electronic evaluation system 26 and the display 30 are embodied as components physically separated from the weighing module 10 in the illustrated embodiment, other embodiments can incorporate one or both of these components 26 and 30 into the weighing module 10.

(10) The electronic evaluation system 26 houses, among other things, a processor 32, which receives data from the load cell 14.

(11) The weighing chamber 16 has a climate module 34, which is designed as a structurally separate unit and which can be mechanically coupled to the rear wall 22 through a disconnectable plug-in connection (hence, is attached in a manner allowing the climate module to be disconnected without destroying it), and, in particular, preferably without the aid of a tool.

(12) For this purpose the rear wall 22 has two slots 36, which are spaced apart from each other and in which flexible locking hooks 38 (see also FIG. 2) engage with the outer housing 40 of the climate module.

(13) FIGS. 2 to 4 show the climate module 34 in more detail.

(14) The outer housing 40 has a number of apertures 42, through which the interior of the outer housing 40 changes over into the weighing chamber 16 and becomes a part of the weighing chamber 16, so that the climate inside the weighing chamber 16 corresponds to the climate inside the outer housing 40.

(15) The climate module 34 is electronically coupled via an electrical plug-in connection to a corresponding plug receptacle 44 in the rear wall 22. The plug receptacle 44 is electrically connected to the processor 32. A plug 46 with contacts 48 is plugged into the plug receptacle 44 on the climate module 34. As a result, the plug 46 forms a module-sided part of the electrical plug-in connection.

(16) As an alternative to an electrical plug-in connection, a wireless transmission, such as WLAN or Bluetooth, can be used.

(17) The electrical plug-in connection (or the wireless transmission used as an alternative) forms a data transmission path, over which the data can be transferred from the climate module 34 to the processor 32 and, if desired, can be transferred back to the climate module.

(18) The plug 46 is preferably a section of a circuit board 50, on which a plurality of sensors for detecting the climate in the weighing chamber 16 are disposed. Therefore, an air temperature sensor 52, an air humidity sensor 54, a light sensor 56, which is arranged directly in the vicinity of an aperture 42, and a sensor 58 for detecting the degree of ionization in the weighing chamber 16 are provided on the circuit board 50, and an electronic memory 60 is also provided on the circuit board. An air pressure sensor 62 is mechanically and electrically coupled to the circuit board 50 with a bracket 64.

(19) A plurality of the sensors can also be combined into combined sensors.

(20) A wall 66 closes the shell-like outer housing 40, so that the narrow tongue-like section of the circuit board 50, which is located to the right of the wall 66 in FIG. 4, can be inserted into the rear wall 22 and the plug receptacle 44.

(21) Each sensor is coupled to the processor 32 via corresponding contacts 48. Similarly the memory 60 is coupled to the processor 32. During the weighing operation the density of the sample to be weighed can be entered into the precision balance, for example, using the display unit 30, which is also used simultaneously as a data input unit by way of, for example, the touch screen. As an alternative, the density of the sample to be weighed can have already been stored.

(22) Then a sample to be weighed is placed on the weighing dish 24.

(23) The air pressure, the air humidity and the air temperature are determined by the sensors 62, 54 and 52, respectively; and the corresponding data are then transmitted to the processor 32.

(24) The air density is determined in the processor 32. The input densities are used in the processor to determine the air buoyancy correction factor and/or the air buoyancy of the sample to be weighed, as a function of the air pressure, the air humidity, the air temperature as well as the density of the sample to be weighed; and the conventional weighing result of the sample to be weighed, i.e., the mass of the sample to be weighed that is corrected by its air buoyancy, is determined and displayed in the display unit 30.

(25) In addition, the weighing value of the sample to be weighed can be corrected via additional parameters, for example, by a known effect of the varying air humidities or temperatures on the weighing result. This feature permits the accuracy of the weighing result to be even higher.

(26) In addition, the calibration values and the correction values for the climate module 34, which had been input during the calibration of the climate module 34, are stored in the memory 60.

(27) This calibration is performed outside of the precision balance. To this end the climate module 34 is simply unplugged from the weighing chamber 16 without having to disconnect a wire connection. Then the climate module 34 is sent to an appropriate calibration institute that stores the number of the calibration certificate, i.e., the new calibration values, the calibration date, the name of the calibration laboratory, the name of the person in charge and the calibration history, in the memory 60. These values are read out later by the application program, when the climate module 34 is once again in the precision balance, and flow directly into the computation. Even the values of the light sensor 56 and the sensor 58 for determining the degree of ionization in the weighing chamber 16 are determined.

(28) For example, when the level of incident light increases, a corresponding signal will be shown on the display that, for example, the measurement is uncertain due to increased exposure to sunlight and, thus, due to a temperature change in the weighing chamber. As a result, the processor sends an output signal as a function of the exposure to incident light.

(29) As soon as the degree of ionization is too high, an ionization device is activated; and this ionization device ionizes the air in the weighing chamber and makes sure that the sample to be weighed is discharged, or a warning about an excessive charge of the sample to be weighed is sent.

(30) The memory 60 is preferably an EEPROM.

(31) In addition, the connection between the climate module 34 and the rest of the precision balance is implemented using an I.sup.2C bus.

(32) The climate module 34 can be connected to a computer via a USB adapter, into which the climate module is inserted, in order to calibrate the sensors 52 to 58 and 62 without having to connect the climate module 34 to the weighing module 10.

(33) As can be seen, the climate module is designed so that it can also be used as a stand-alone unit external to a balance and can be connected to a USB port of a PC using an I.sup.2C bus.

LIST OF REFERENCE NUMERALS

(34) 10 weighing module 12 base 14 load cell 16 weighing chamber 18 side wall 20 front wall 22 rear wall 24 weighing dish 26 evaluation system 28 cable 30 display unit 32 processor 34 climate module 36 slots 38 locking hooks 42 apertures 46 plug 48 contacts 50 printed circuit board 52 air temperature sensor 54 air humidity sensor 56 light sensor 58 sensor 60 memory 62 air pressure sensor 64 bracket 66 wall