Shimadzu Corporation

Kunio Shimauchi

Hiroshi Hamamoto

Akira Komoto

Atushi Iiduka

Kimitoshi Tamura

Nobuyuki Yoshikuwa

Tsuyoshi Satoh

Akihiro Fukai

Kazuo Nishibayashi

To enhance the precision in balancing measurement, an electronic balance is provided. The electronic balance includes a door open/close detection sensorfor detecting the open/close of a door; a weighing precision setting unit, for setting a weighing precision; a calculation unit, for calculating an average time for balancing measurement that is as short as possible and satisfies the weighing precision or an average number of pieces of data; and a selection unit, for selecting an average time for weight measurement or an average number of pieces of data when the opening of the dooris detected by the sensor, and selecting an average time of normal measurement or an average number of pieces of data when the closing of the dooris detected by the sensor, and an averaging process is performed with the average time or the average number of pieces of data that is being selected.

Target weight balance the selects between different weighing methods after the door has been opened

[Problems] To obtain a stable measurement result in both a measuring-out mode and normal mode, and to obtain a weight value eliminating the influence of convection in the windshield. [Means for Solving Problems] An electronic balance with a windshield, the windshield surrounding a measuring panand having an openable/closable door, for averaging measurement data in a response time and obtaining a weight value based on it, the electronic balance including: a door open/close detection sensorfor detecting an open/close of the door; and a mode changer for switching the measurement mode between a measuring-out mode in which the response time is relatively short when the dooris open, and a normal mode in which the response time is relatively long when the dooris closed. In addition, in a convection time measurement mode, a convection time period since the door is closed with no sample on the measuring panuntil the fluctuation of the measurement data is settled down within a predetermined range is measured and memorized. After the memorized convection time has passed after a sample was put on the measuring panand the doorwas closed in a normal measurement mode, the measurement data is averaged in a predetermined response time and the weight value is calculated.

Electronic balance with windshield

Disclosed is an electromagnetic-force-balancing-type electronic balance having a magnetic circuit which includes a yoke, a first permanent magnet, a pole piece, a second permanent magnetand a cover. A connection membermade of a magnetic material is disposed in an air-gap region included in the magnetic circuit. The connection membermay be disposed between the second permanent magnetand the coveror between the coverand the yoketo facilitate assembling operations. Alternatively, first and second gap-defining membersmade of a non-magnetic material may be disposed, respectively, between the first permanent magnetand the yokeand between the second permanent magnetand the cover, to provide symmetric properties in magnetic sub-circuits so as to counteract an imbalance in hysteresis characteristic. The present invention can suppress adverse influences of a magnetic resistance caused by an air gap existing in the magnetic circuit of the electronic balance.

Electromagnetic-force-balancing-type electronic balance

An electronic balance of an electromagnetic force balancing type comprises electromagnetic force generators for applying electromagnetic forces for controlling to move a balance beam in a longitudinal direction (X axis) and a horizontal direction (Y axis) orthogonal thereto, PID controllers for controlling the electromagnetic force generators by a PID control, and a three axes directions position detector for detecting displacements in three directions of X, Y axes directions of the balance beam and a gravitational force direction.

Electronic balance having a position control mechanism

In electronic balance, an analog computation portion determines at least a differential control signal according to an amount of displacement of a beam. A digital computation portion determines at least an integral control signal is determined by after the amount of displacement of the beam is digital-converted. The control signal component determined by the digital computation portion is analog-converted. Thereafter, a synthetic PID control signal is determined by being synthesized from a resultant signal and the control signal component, which is determined by the analog computation portion. Subsequently, a coil current based on the synthetic PID control signal is passed through the coil. A weight value is obtained according to the control signal component determined by the digital computation portion.

Electric balance with synthetic PID control signal

A floor portion separates a weighing chamber encircled by a windshield case and accommodating a weighing pan, and a balance body accommodating a load detecting section, an incorporated weight, etc. A plurality of vents is provided through the floor portion. A movable floor is arranged to be able to move back and forth on supporting members. A plurality of vents is provided through the movable floor on the rear side of the floor portion so that number and center position of the vents of the movable floor is the same as the vents of the floor portion. When a temperature difference between the temperatures within the weighing chamber and within the balance body is large, the movable floor is moved to permit airflow between the weighing chamber and the balance body.

Electronic balance

In a top scale balance which has a Roberval's chain 10 and a load weight transmitting lever 30 and in which a movable post 13 of the Roberval's chain 10 is connected to a point of force 32 of the lever 30 through an elastic connection fulcrum 51, a horizontal member 12 nearer to the elastic connection fulcrum 51, out of upper and lower horizontal members 11, 12 of the Roberval's chain 10, is greater in rigidity than the other horizontal member 11. Alternately, the upper and lower horizontal members 11, 12 are equal in rigidity and the elastic connection fulcrum 51 is positioned, in the vertical direction, at the center between the upper and lower horizontal members 11, 12. Such an arrangement prevents or reduces the movement of the elastic connection fulcrum 51 in the back-and-forth direction due to an offset placed load. Thus, even though the top scale balance is made in a compact and thin design with the lever ratio increased, the top scale balance is high in precision with a less offset position error.

Top scale balance

Method and apparatus for calibrating the sensitivity and linearity of the weighing means of an electronic balance, wherein a sensitivity calibration is automatically conducted when the ambient temperature has changed a first predetermined amount or a predetermined period of time has passed since the previous calibration was conducted, and when a sensitivity calibration is conducted, it is checked whether or not the temperature change has exceeded a second predetermined amount greater than the first predetermined amount, and only when the temperature change has exceeded the second predetermined amount since the previous linearity calibration was conducted, a linearity calibration is conducted along with the sensitivity calibration.

An electronic balance devised so that the weighing pan of the balance may settle down fast to make the balance indicate a correct value of measurement quickly without being long disturbed by the air turbulence arising when the door of the weighing pan protecting chamber of the balance is opened and continuing for a while after the door has been closed. This electronic balance is provided witha heater on the base portion of the weighing pan protecting chamber so that the heater is located just below the door of the chamber. The heater generates hot air streams rising upward therefrom along the outer surface of the door. When the door is opened, the air streams play a role of an air curtain to prevent a possible air exchange between the hotter chamber warmed by the electronic circuit of the balance and the cooler surrounding atmosphere.

Growing community of inventors

Kyoto, Japan

Kunio Shimauchi