JP2020134452A - Electronic force balance - Google Patents

Abstract

To provide an electronic force balance capable of reducing before using the error factor in weighing not more than 0.1 mg.SOLUTION: The electronic force balance includes: a balance body including a built-in load measuring mechanism; a door mechanism for opening and closing a door with a drive unit, which is arranged in an upper area of the balance enclosing the weighing chamber; a windshield having a static eliminator to remove static electricity behind the weighing chamber; a timer unit that detects the arrival of a set time or a fixed timing; and a control unit that controls the opening and closing of the door and the operation of the static eliminator based on the detection.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electronic balance.

As a balance for precisely measuring the mass of powder and other various samples, an electromagnetic balance type balance with a windshield (hereinafter, an electromagnetic balance type balance) for measuring by installing a sample weighing part in a windshield is referred to as an "electronic balance". ) Is often used.

In order to improve workability, a balance with a windshield is disclosed in which the opening and closing of the door can be easily switched between manual opening and closing and the opening and closing movement of the door is extremely smooth and inexpensive. For example, Patent Document 1).

Further, the door is provided with a control means for generating a trigger signal at predetermined time intervals, or when a predetermined temperature change or a predetermined humidity change occurs, and a door opening / closing mechanism that automatically opens and closes the door by the trigger signal. (For example, Patent Document 2) discloses an electronic balance that opens and closes a door to execute a convection time measurement mode when a problem occurs. Upon receiving the trigger signal, the electronic balance automatically opens the door of the windshield, and after a lapse of a predetermined time, automatically closes the door to generate convection in the windshield in the same manner as when manually performed. Eventually, it is detected that the load change due to convection is within a predetermined range, and the time elapsed from closing the door until the convection is settled is updated as the convection time Tco. By automating the processing of the convection time measurement mode in this way, the update of the convection time is forgotten, the opening and closing operation of the door for causing the convection is unified, the variation is eliminated, and the measurement accuracy is improved.

Japanese Unexamined Patent Publication No. 09-015031 International Publication No. WO2006 / 082915

In an electronic balance with a weighing sensitivity of 0.1 mg or less, for example, when the ambient temperature change exceeds 2 ° C./hour, convection increases in the weighing chamber, which affects the weighing pan.

Further, when the temperature difference between the weighing chamber and the inside of the housing becomes large, the temperature difference between the periphery of the built-in weight and the weighing chamber becomes large. In this way, when the temperatures inside the weighing chamber and the balance body are different, the air densities inside the weighing chamber and the balance body are different, and there is a difference in the buoyancy received by the object to be placed on the weighing dish and the calibration weight. Occurs and causes an error in the measured value.

Furthermore, when the air flow in the weighing chamber caused by the opening and closing of the windshield door and the above temperature difference comes into contact with the glass wall surface forming the weighing chamber, static electricity is generated on the glass surface, and the sensitivity is calibrated (adjusted). There will be an error during measurement.

In response to this problem, in Patent Document 2, the door is automatically opened and closed by a trigger signal generated at predetermined time intervals, or when a predetermined temperature change or a predetermined humidity change occurs, and the influence of convection is exerted. Although it is suppressed, it does not disclose anything about static electricity, and it is not possible to deal with measurement errors caused by static electricity generated in the windshield.

The present invention provides, as one aspect, an electronic balance that reduces an error factor in weighing 0.1 mg or less before the user uses it.

The electronic balance according to one aspect of the present invention includes a balance body having a built-in load measuring mechanism, a door mechanism arranged on the upper part of the balance body, surrounding a weighing chamber, and opening and closing a door by a drive unit. A windshield having a static eliminator that removes static electricity behind the weighing chamber, a timekeeping unit that detects the arrival of a set time or a certain timing, opening and closing the door and opening and closing the static eliminator based on the detection. It is characterized by including a control unit for controlling the operation.

The control unit is characterized in that the door is opened based on the detection, the door is closed after a predetermined time has elapsed, and the static elimination unit is driven.

The electronic balance further includes a humidity detection unit for measuring humidity, and when the door is closed, the control unit charges the static elimination unit according to the measurement result by the humidity detection unit and the setting of the user. It is characterized by being driven.

The balance further includes a temperature detection unit for measuring temperature and a setting unit for setting time, temperature change, and humidity change, and the control unit can be used with the set time, temperature change, or humidity change. It is characterized in that the opening and closing of the door and the operation of the static eliminator are controlled based on the detection result by the time measuring unit, the humidity detecting unit or the temperature detecting unit.

According to one aspect of the present invention, the error factor in weighing 0.1 mg or less can be reduced before the user uses it.

It is a perspective view which shows an example of the electronic balance in this embodiment. It is a block diagram which shows the structural example of the electronic balance main body in Example 1 of this Embodiment. It is a flowchart which shows the door opening-opening and static elimination processing of a control part in Example 1 of this Embodiment. It is a block diagram which shows the structural example of the electronic balance main body in Example 2 of this Embodiment. It is a flowchart which shows the static elimination process of the control part in Example 2 of this Embodiment.

FIG. 1 is a perspective view showing an example of an electronic balance according to the present embodiment. The electronic balance 1 includes a windshield 2 and an electronic balance main body 4. The windshield 2 is formed of, for example, a top plate 2a, a left side wall 2b, a right side wall 2c, a front side wall 2d, and a rear side wall 2e. The top plate 2a, the left side wall 2b, the right side wall 2c, and the front side wall 2d are made of, for example, transparent glass or plastic. The rear side wall 2e is made of, for example, glass, metal or plastic.

The top plate 2a, the left side wall 2b, and the right side wall 2c are each mounted on rails provided on a frame body constituting the windshield so as to be slidable, and handles 3a, 3b, and 3c are provided, respectively. When the handles 3a, 3b, 3c are slid toward the rear side wall 2e, the top plate 2a, the left side wall 2b, and the right side wall 2c are also slid as doors, and the sample is placed on the measuring plate 5 of the electronic balance body 4. can do.

Further, the top plate 2a, the left side wall 2b, and the right side wall 2c can be automatically opened and closed by sliding by power as described later.

A weighing pan 5 is installed in the center of the upper part of the electronic balance main body 4, and a sample to be weighed can be placed on it. Further, an input unit 6 and a display unit 7 are provided on the front surface of the electronic balance body 4. The input unit 6 is used when giving an instruction to start weighing, starting a calibration process, or inputting an instruction when operating the electronic balance 1. The display unit 7 displays a measurement result, a menu corresponding to the input by the input unit 6, and the like.

Further, a static eliminator (ionizer) is attached to the rear side wall 2e in order to remove static electricity generated in the windshield 2.

FIG. 2 is a block diagram showing a configuration example of the electronic balance main body according to the first embodiment of the present embodiment. The electronic balance body 4 includes a weighing mechanism 11, a door opening / closing mechanism 12, a static elimination unit 14, a control unit 15, a timer 19, and a memory 20 in an internal space partitioned by a metal housing.

The weighing mechanism 10 is an electromagnetic force equilibrium portion including a lever, a fulcrum, an electromagnetic coil (force coil), and a permanent magnet. The electromagnetic coil is a movable electromagnetic coil of an electromagnetic force generator fixed to the other end of the lever. The permanent magnet is fixed to the metal housing of the electronic balance body 4. When an electric current flows through the electromagnetic coil, a magnetic field is generated and becomes an electromagnet, and a repulsive force / attractive force acts with the permanent magnet. The magnitude of the electromagnetic force varies depending on the strength of the current flowing through the electromagnetic coil.

When measuring the mass of the object to be measured, the displacement detector detects the displacement of the lever, and the current flowing through the electromagnetic coil is feedback-controlled so that the lever does not displace. In this case, the larger the mass of the object to be measured, the larger the current value flowing through the electromagnetic coil. Therefore, the mass of the object to be measured can be measured based on the current value flowing through the electromagnetic coil.

The door opening / closing mechanism 12 includes a motor 13 and is a mechanism for opening / closing the top plate 2a, the left side wall 2b, and the right side wall 2c of the windshield 2. The door opening / closing mechanism 12 has, for example, a rack provided on a side (edge) horizontal to the sliding direction of the top plate 2a, the left side wall 2b, and the right side wall 2c, and the rack is slid in the sliding direction by a pinion provided on the motor 13. It may be a mechanism to move to. Further, the door opening / closing mechanism 12 may include a speed reducer in order to obtain a required torque and rotation speed from the motor 13.

Further, when the motor 13 is not driven, the door opening / closing mechanism 12 may include a clutch mechanism so that the top plate 2a, the left side wall 2b, and the right side wall 2c can be opened and closed manually. The clutch mechanism may be used to remove one of the gears that are in mesh with each other in the power transmission system from the motor 13 to the pinion that drives the rack. As a result, since no load is applied to the power transmission system while the gear is disengaged by the clutch mechanism, the top plate 2a, the left side wall 2b, and the right side wall 2c can be manually opened and closed.

Further, in the door opening / closing mechanism 12, for example, a wire is fixed to a side (edge) horizontal to the sliding direction of the top plate 2a, the left side wall 2b, and the right side wall 2c, and the wire is wound by a motor. A mechanism may be used in which the top plate 2a, the left side wall 2b, and the right side wall 2c are used as doors to move along the rail in the sliding direction. When this configuration is adopted, for example, two wires are fixed to both ends of the side (edge), and when the door is opened, the wire fixed to one end of the side (edge) is wound by the first motor. When closing the door, the wire fixed to the other end of the side (edge) may be wound by the second motor. At this time, the other motor that does not wind up may be configured to be separated from the power transmission system so as not to give a load to the motor used at the time of winding, or if it is not driven, the shaft of the motor rotates. It may be movable.

The door opening / closing mechanism 12 may include a potentiometer, a position detection sensor, and the like, whereby the amount of movement of the top plate 2a, the left side wall 2b, and the right side wall 2c in the sliding direction may be adjusted. Further, the electronic balance body 4 may be provided with a door open / close detection sensor that detects whether the top plate 2a, the left side wall 2b, and the right side wall 2c are in a closed state. The door opening / closing mechanism 12 described above is an example, and is not limited thereto.

The control unit 15 is a processor that controls the overall operation of the electronic balance 1, and is, for example, a central processing unit (CPU). The control unit 15 functions as a measuring unit 16, a door opening / closing mechanism control unit 17, and a static elimination control unit 18.

The weighing unit 18 calculates the displacement of the other end of the lever based on the detection signal detected by the optical position sensor in the weighing mechanism 11, so that the displacement of the other end of the lever becomes 0. Control is performed to determine the magnitude of the current supplied to the electromagnetic coil. At the same time, the measuring unit is placed on the object to be measured or the calibration weight tray placed on the measuring tray due to the magnitude of the current flowing through the electromagnetic coil in the equilibrium state where the displacement of the other end of the lever becomes zero. Control is performed to obtain the load of the calibration weight.

The door opening / closing mechanism control unit 17 drives the motor 13 to operate the door opening / closing mechanism 12 based on a command by a predetermined program, the arrival of a predetermined timing by a timer (not shown), a command from the input unit 6, or the like. The doors (top plate 2a, left side wall 2b, and right side wall 2c) are opened and closed.

The memory 20 is a non-volatile storage device such as a flash memory, and stores information such as measured values and calibration contents. The timer 19 measures the date and time, the time, and the fixed time.

FIG. 3 is a flowchart showing the door opening / closing and static elimination processing of the control unit in the first embodiment of the present embodiment. The user sets in advance the time for executing the process according to the present embodiment by the input unit. The set time information is stored in the memory 20.

The door opening / closing mechanism control unit 17 acquires the time information measured by the timer 19 (S1). The door opening / closing mechanism control unit 17 reads the time information from the memory 20 and compares it with the time information from the timer 19 to determine whether the set time has arrived (S2). If the set time has not arrived (NO in S2), the process returns to S1.

When it is determined that the set time has arrived (YES in S2), the door opening / closing mechanism control unit 17 drives the motor 13 in the direction in which the door opens and slides the door so as to open the predetermined width door (S3). When the predetermined width door is opened, the door opening / closing mechanism control unit 17 stops driving the motor 13 (S4).

The door opening / closing mechanism control unit 17 waits in the state of S4 until T1 elapses for a predetermined time (NO in S5). When the predetermined time T1 has elapsed (YES in S5), the door opening / closing mechanism control unit 17 drives the motor 13 in the direction in which the door closes (S6). When the door is closed, the door opening / closing mechanism control unit 17 stops driving the motor 13 (S7).

When the static elimination control unit 18 has not yet operated the static elimination device 14 in this flow (NO in S8), the static elimination control unit 18 operates the static elimination device 14 (S9). The static elimination control unit 18 waits until T2 elapses for a predetermined time in a state where the static elimination device 14 is operated (NO in S10). When the predetermined time T2 has elapsed (YES in S10), the static elimination control unit 18 stops the operation of the static elimination device 14 (S11).

The static elimination control unit 18 waits until a predetermined time T3 elapses after stopping the driving of the motor 13 in S7 (NO in S12, YES in S8).

After the elapse of the predetermined time T3, this process ends (YES in S12).

The flowchart shown in FIG. 3 is an example of the processing according to the present embodiment, and is not limited to this. For example, in S1 to S2, the processing of S3 or higher may be performed at regular time intervals.

According to the first embodiment, for example, the door is left open for 30 minutes, then closed for 5 minutes, and the static eliminator 24 is operated for 1 minute to remove static electricity generated by friction between the air flow such as convection and the glass. can do. As a result, among the error factors that cause problems in weighing 0.1 mg or less, sensitivity adjustment error, convection error, and error due to static electricity can be reduced before the user uses the error. In particular, since the static electricity generated by the convection in the windshield 2 can be removed, the error due to the static electricity can be reduced.

Further, when the humidity or temperature around the electronic balance changes while the door is closed, the static eliminator may be operated. In the second embodiment below, this case will be described.

FIG. 4 is a block diagram showing a configuration example of the electronic balance main body according to the second embodiment of the present embodiment. The electronic balance 1a of FIG. 4 is obtained by adding a door open / close detection sensor 31, a humidity sensor 32, and a temperature sensor 33 to the electronic balance 1 of FIG. The door open / close detection sensor 31 is a sensor for detecting the open / closed state of the door (top plate 2a, left side wall 2b, and right side wall 2c). The humidity sensor 32 is a sensor that measures humidity. The temperature sensor 33 is a sensor that measures the temperature.

FIG. 5 is a flowchart showing a static elimination process of the control unit according to the second embodiment of the present embodiment. The user sets in advance a threshold value for humidity and a threshold value for temperature as condition information by the input unit 6. The set condition information is stored in the memory 20. The threshold value may be set in advance at the time of shipment from the factory, for example.

When the static elimination control unit 18 detects that the doors (top plate 2a, left side wall 2b, and right side wall 2c) are closed by the door open / close detection sensor 31 (YES in S21), the static elimination control unit 18 is a humidity sensor. The measurement result from the 32 and / or the temperature sensor 33 is acquired (S22).

The static elimination control unit 18 reads condition information from the memory 20 and compares it with the measurement results from the humidity sensor 32 and / or the temperature sensor 33, and determines whether the measurement results satisfy the conditions included in the condition information (S23). If the measurement result does not satisfy the condition (NO in S23), the process returns to the process of S22.

When the measurement result satisfies the condition (YES in S23), the static elimination control unit 18 operates the static elimination device 14 (S24). For example, when the humidity at the present time is lower than the threshold value set by the condition or when the temperature at the present time is lower than the threshold value set by the condition, the static elimination control unit 18 operates the static elimination device 14.

The static elimination control unit 18 operates the static elimination device 14 for a predetermined time (NO, S24 in S25), and stops the static elimination device 14 after a predetermined time elapses (S26).

According to the second embodiment, among the error factors that cause a problem in weighing 0.1 mg or less, the sensitivity adjustment error, the convection error, and the error due to static electricity can be reduced before the user uses the error. In particular, by paying attention to humidity and temperature, even if static electricity is generated after the door is closed, the static electricity eliminator 14 can be operated to remove the static electricity, so that the error due to the static electricity can be reduced.

As described above, the electronic balance (for example, electronic balances 1, 1a) according to the present embodiment is
A balance body (for example, an electronic balance body 4) with a built-in load measuring mechanism,
A door mechanism (eg, the top plate 2a, the left side wall 2b, and the right side wall 2c, if hired) that is arranged on the upper part of the balance body, surrounds the weighing chamber, and opens and closes the door (if hired, the top plate 2a, the left side wall 2b, and the right side wall 2c) by a drive unit (for example, a motor 13). , A door opening / closing mechanism 12) and a windshield (for example, windshield 2) having a static eliminator (for example, a static eliminator 14) for removing static electricity behind the weighing chamber.
A timekeeping unit (for example, timer 19) that detects the arrival of a set time or a fixed timing,
A control unit (for example, control unit 15) that controls the opening / closing of the door and the operation of the static eliminator based on the detection.
To be equipped.

With this configuration, the error factor in weighing 0.1 mg or less can be reduced before the user uses it. In particular, since static electricity generated by convection in the windshield 2 can be removed, an error due to static electricity can be reduced. In addition, since the error factor can be removed before the user uses it, the user can use the electronic balance immediately when he / she wants to use it, and does not have to wait for the time to remove the error factor.

The control unit opens the door based on the detection, closes the door after a lapse of a predetermined time, and drives the static elimination unit.

With this configuration, among the error factors that cause problems in weighing 0.1 mg or less, sensitivity adjustment error, convection error, and error due to static electricity can be reliably reduced before the user uses it.

The electronic balance further
A humidity detector (for example, a humidity sensor 32) for measuring humidity is provided.
When the door is closed, the control unit drives the static eliminator (for example, the static eliminator 14) according to the measurement result by the humidity detection unit and the setting of the user.

With this configuration, even if the humidity becomes such that static electricity is likely to be generated after the door is closed, the static eliminator can be driven to remove the static electricity, so that the user can use the error due to static electricity. Can be mitigated before.

The balance is further
A temperature detector (for example, a temperature sensor 33) that measures the temperature,
It is equipped with a setting unit (for example, input unit 6) for setting the time, temperature change, and humidity change.
The control unit (for example, the control unit 15) has the door based on the set time, the temperature change or the humidity change, and the detection result by the timekeeping unit, the humidity detection unit or the temperature detection unit. Controls the opening and closing of the static eliminator and the operation of the static eliminator.

With this configuration, by setting the time, temperature change, humidity change, etc. in advance, the door can be automatically opened and closed and the static eliminator can be operated when the conditions are met. Therefore, among the error factors that cause problems in weighing 0.1 mg or less, the sensitivity adjustment error, the convection error, and the error due to static electricity can be reduced before the user uses the error. Therefore, when the user uses the electronic balance, it is not necessary for the user to perform the work of removing the error factor in advance, so that the measurement work can be performed efficiently.

The present embodiment has been described above based on the embodiments and modifications, but the embodiments of the above-described embodiments are for facilitating the understanding of the present embodiment, and do not limit the present embodiment. This aspect can be modified or improved without departing from its purpose and claims, and this aspect includes its equivalents. Moreover, if the technical feature is not described as essential in this specification, it may be deleted as appropriate.

1 Electronic balance 2 Windshield 4 Electronic balance body 5 Weighing pan 6 Input unit 7 Display unit 11 Weighing mechanism 12 Door opening / closing mechanism 13 Motor 14 Static eliminator 15 Control unit 16 Weighing unit 17 Door opening / closing mechanism Control unit 18 Static elimination control unit 19 Timer 20 Memory 31 Door open / close detection sensor 32 Humidity sensor 33 Temperature sensor

Claims (4)

The balance body with a built-in load measuring mechanism and
A door mechanism arranged on the upper part of the balance body, which surrounds the weighing chamber and opens and closes the door by a drive unit, and a windshield having a static eliminator in the weighing chamber to remove static electricity.
A timekeeping unit that detects the arrival of a set time or a certain timing,
A control unit that controls the opening and closing of the door and the operation of the static eliminator based on the detection.
An electronic balance characterized by being equipped with. The electronic balance according to claim 1, wherein the control unit opens the door based on the detection, closes the door after a lapse of a predetermined time, and drives the static elimination unit. The electronic balance further
Equipped with a humidity detector that measures humidity
The electronic balance according to claim 1 or 2, wherein the control unit drives the static elimination unit when the door is closed, according to the measurement result by the humidity detection unit and the setting of the user. .. The balance is further
A temperature detector that measures the temperature and
Equipped with a setting unit to set the time, temperature change, and humidity change
The control unit opens and closes the door and the static eliminator based on the set time, the temperature change or the humidity change, and the detection result by the timekeeping unit, the humidity detection unit or the temperature detection unit. The electronic balance according to claim 3, wherein the operation of the electronic balance is controlled.

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