JP2020020713A - Static eliminator and electronic balance - Google Patents

Abstract

To provide a static eliminator and an electronic balance that have a wide static elimination range and a small variation in ion balance.SOLUTION: A static elimination time determination unit 62 performs operation based on a predetermined ratio for a set static elimination time and thereby determines: a first static elimination time in which positive voltage and negative voltage are alternately applied to a discharge unit 3 at a first frequency; and a second static elimination time in which positive voltage and negative voltage are alternately applied to the discharge unit 3 at a second frequency higher than the first frequency. A static elimination control unit 63 alternately applies positive voltage and negative voltage to the discharge unit 3 at the first frequency for the first static elimination time; and after that, alternately applies positive voltage and negative voltage to the discharge unit 3 for the second static elimination time at the second frequency, thereby causing positive ions and negative ions to be discharged from the discharge unit 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a static eliminator provided with a discharge section for emitting positive ions and negative ions, and an electronic balance provided with the same.

  The electronic balance is provided with a weighing dish on which the measurement target is placed, and a weighing unit that measures the mass of the measurement target placed on the weighing dish. Since the mass of the measurement object measured by the measuring unit fluctuates due to the influence of static electricity, it is preferable to remove static electricity from the measurement object using a static eliminator (for example, see Patent Document 1 below).

  As the static eliminator, two types, an AC system and a DC system, are known. In an AC type static eliminator, when an AC voltage is applied to one electrode (discharge needle), positive and negative ions are emitted from the electrode in equal amounts. On the other hand, in the DC type static eliminator, when a DC voltage is applied to each of the positive electrode and the negative electrode, positive ions are emitted from the positive electrode and negative ions are emitted from the negative electrode.

  When a DC type static eliminator is used, when one of the positive electrode and the negative electrode is degraded, the amount of ions emitted from each electrode varies, resulting in a problem that the ion balance is deteriorated. For this reason, it is preferable to use an AC type static eliminator instead of a DC type in an electronic balance requiring more accurate measurement.

JP-A-2006-170176

  In the AC type static eliminator, positive ions and negative ions are emitted from one electrode, and thus are easily combined with each other immediately after the positive ions and negative ions are emitted. Therefore, there is a problem that it is difficult for the positive ions and the negative ions to reach far, and the charge removal range is narrow.

  Therefore, if the frequency of the AC voltage applied to one electrode is reduced, the positive ions and the negative ions can be easily transmitted to a long distance, so that the charge removal range can be widened. However, in this case, since the fluctuation of the ion balance becomes large, there is a problem that the mass of the measurement object measured by the measuring unit varies.

  The present invention has been made in view of the above circumstances, and has as its object to provide a static eliminator and an electronic balance having a wide static elimination range and a small fluctuation in ion balance.

(1) A static elimination device according to the present invention includes a discharge unit, a setting reception unit, a static elimination time determination unit, and a static elimination control unit. The discharge unit emits positive ions and negative ions. The setting receiving unit receives a setting of a static elimination time. The static elimination time determining unit performs an arithmetic operation based on a predetermined ratio with respect to the set static elimination time, so that a first static elimination time in which a positive voltage and a negative voltage are alternately applied to the discharge unit at a first frequency, and And determining a second static elimination time in which a positive voltage and a negative voltage are alternately applied to the discharge unit at a second frequency higher than the first frequency. The static elimination control unit applies a positive voltage and a negative voltage to the discharge unit alternately at the first frequency during the first static elimination time, and then applies a positive voltage and a positive voltage to the discharge unit during the second static elimination time. By applying a negative voltage alternately at the second frequency, positive ions and negative ions are emitted from the discharge unit.

  According to such a configuration, during the first static elimination time in which the positive voltage and the negative voltage are alternately applied to the discharge unit at the relatively low first frequency, the positive ions and the negative ions can easily reach far. Therefore, the range of static elimination can be expanded. Further, during the second static elimination time after which the positive voltage and the negative voltage are alternately applied to the discharge unit at the relatively high second frequency, the fluctuation of the ion balance can be reduced. Thereby, after performing static elimination over a wide range in a short time during the first static elimination time, static elimination can be performed while suppressing fluctuations in the ion balance during the second static elimination time. It is possible to do.

(2) The electronic balance according to the present invention is provided with the static eliminator, a main body having a weighing chamber from which positive ions and negative ions are released from the static eliminator, and the weighing chamber, on which the object to be measured is mounted. A weighing dish to be placed.

  According to such a configuration, the static elimination range is wide, and, using a static eliminator having a small variation in ion balance, static elimination of the measurement target placed on the weighing dish is performed, and the mass of the measurement target is reduced. Can be measured. Thereby, the mass of the measurement object can be measured with higher accuracy.

  According to the present invention, during the first static elimination time, the neutralization range can be expanded, and during the subsequent second static elimination time, the fluctuation of the ion balance can be reduced.

FIG. 1 is a block diagram illustrating a configuration example of an electronic balance according to an embodiment of the present invention. FIG. 4 is a diagram for explaining a relationship between a voltage applied to a discharge unit and ions emitted from the discharge unit, and shows a case where a voltage is applied at a relatively high frequency. FIG. 4 is a diagram for explaining a relationship between a voltage applied to a discharge unit and ions emitted from the discharge unit, and shows a case where a voltage is applied at a relatively low frequency. It is a figure for explaining control of the voltage applied to the discharge part at the time of the conventional static elimination. FIG. 9 is a diagram showing a change over time of the surface potential of a measurement target when static electricity of the measurement target is removed by conventional static elimination. It is a figure for explaining control of the voltage applied to the discharge part at the time of static elimination in this embodiment. FIG. 4 is a diagram illustrating a change over time of a surface potential of a measurement target when static electricity of the measurement target is removed by static elimination in the present embodiment. 9 is a flowchart illustrating an example of control by a control unit when measuring the mass of the measurement target.

1. FIG. 1 is a block diagram showing a configuration example of an electronic balance according to an embodiment of the present invention. This electronic balance is for measuring the mass of the measurement object W, and includes a weighing dish 1, a load detection unit 2, a discharge unit 3, an operation unit 4, a display unit 5, a control unit 6, and the like.

  An object W to be measured is placed on the upper surface of the weighing dish 1. In the electronic balance according to the present embodiment, in addition to the sample made of powder, various types of measurement objects W can be placed on the weighing dish 1 to measure the mass. The periphery of the weighing dish 1 is covered with, for example, an openable / closable windshield case (not shown), and a weighing chamber 8 is formed in the windshield case.

  The load detection unit 2 detects the load of the measurement target W placed on the weighing dish 1 provided in the weighing chamber 8. By detecting the load that the weighing dish 1 receives from the measurement target W by the load detection unit 2, the mass of the measurement target W can be measured based on the load. As a method of detecting the load in the load detecting section 2, an electromagnetic method or a load cell method can be exemplified.

  When the load detection unit 2 is an electromagnetic type, for example, a magnet, a coil, and the like are provided in the load detection unit 2. In this case, by applying a current to the coil to apply an electromagnetic force so as to balance the load of the measurement target W placed on the weighing dish 1, the load of the measurement target W is determined based on the current amount at that time. Can be detected.

  When the load detector 2 is a load cell type, the load detector 2 is provided with a strain body formed of, for example, aluminum or the like. In this case, when the object to be measured W is placed on the weighing dish 1, the flexure element flexes, and the amount of flexure is detected as an electric signal using a strain gauge or the like, so that measurement is performed based on the electric signal. The load on the object W can be detected. However, the load detection unit 2 is not limited to the electromagnetic type or the load cell type, and may be configured to detect the load by another detection method such as a tuning fork type.

  The discharge unit 3 removes static electricity of the measurement target W placed on the weighing dish 1 by emitting positive ions and negative ions into the weighing chamber 8. The discharge unit 3 is configured by an AC type static eliminator (ionizer), and includes one electrode (discharge needle) 31. When an AC voltage is applied to the electrode 31, positive ions and negative ions are emitted from the electrode 31 in equal amounts. By the positive ions and the negative ions released from the discharge unit 3, static electricity of the measurement object W on the weighing dish 1 can be neutralized and removed in a non-contact manner.

  The operation unit 4 includes, for example, a plurality of keys. The user can perform various setting operations by operating the operation unit 4. The display unit 5 is configured by, for example, a liquid crystal display. The display unit 5 displays various information such as the measurement result of the mass of the measurement target W.

  The control unit 6 is configured to include, for example, a CPU (Central Processing Unit). The control unit 6 is electrically connected to the load detection unit 2, the discharge unit 3, the operation unit 4, the display unit 5, and other components. The control unit 6 functions as a setting receiving unit 61, a static elimination time determining unit 62, a static elimination control unit 63, a display processing unit 64, and the like when the CPU executes the program.

  The setting receiving unit 61 receives setting information input by operating the operation unit 4. For example, when the user operates the operation unit 4 to set the time for discharging the positive ions and the negative ions from the discharge unit 3 to perform the charge elimination (the charge elimination time), the setting of the charge elimination time is accepted. Accepted by the unit 61.

  The static elimination time determining unit 62 determines a first static elimination time and a second static elimination time based on the setting of the static elimination time received by the setting receiving unit 61. That is, the set static elimination time is divided into two static elimination times (a first static elimination time and a second static elimination time) by the static elimination time determination unit 62. The static elimination time determining unit 62 calculates a first static elimination time and a second static elimination time by multiplying the set static elimination time by a predetermined ratio. However, if the static elimination time determination unit 62 is configured to perform an operation based on a predetermined ratio with respect to the set static elimination time, the first static elimination time and the second static elimination time are calculated by an operation other than multiplication. Is also good. Further, the ratio may be arbitrarily set and changed.

  The static elimination control unit 63 causes the discharge unit 3 to emit positive ions and negative ions by controlling the voltage applied to the electrode 31 of the discharge unit 3. The charge removal control unit 63 controls the voltage applied to the electrode 31 in a different manner between the first charge removal time and the second charge removal time. Thereby, the positive ions and the negative ions released from the discharge unit 3 can be changed between the first static elimination time and the second static elimination time during the set static elimination time.

  The display processing unit 64 controls display on the display unit 5. Specifically, the display processing unit 64 causes the display unit 5 to display the measurement result of the mass of the measurement target W based on the detection signal of the load detection unit 2. The display processing unit 64 can also perform display on the display unit 5 according to control by the charge removal control unit 63.

  The discharge unit 3 and the control unit 6 in the present embodiment constitute a static eliminator for removing static electricity from the measurement target W. The static eliminator is provided in a main body 9 of the electronic balance, and positive ions and negative ions are emitted from the static eliminator into a weighing chamber 8 formed in the main body 9. The main body 9 is configured by a housing including the windshield case described above.

2. Control of Discharge Unit The voltage applied to the electrode 31 of the discharge unit 3 is alternately switched between a positive voltage and a negative voltage at a predetermined frequency. That is, when removing static electricity from the measurement target W, the charge removal control unit 63 performs control so that a positive voltage and a negative voltage are alternately applied to the discharge unit 3 at a predetermined frequency. The neutralization control unit 63 can also apply a voltage by changing the frequency.

  2A and 2B are diagrams for explaining the relationship between the voltage applied to the discharge unit 3 and the ions emitted from the discharge unit 3. FIG. FIG. 2A shows a case where a voltage is applied at a relatively high frequency, and FIG. 2B shows a case where a voltage is applied at a relatively low frequency.

  As shown in FIG. 2A, when a positive voltage and a negative voltage are alternately applied at a relatively high frequency, positive ions and negative ions are emitted from the discharge unit 3 during a relatively short cycle T. This cycle T is divided into a period T / 2 in which positive ions are emitted and a period T / 2 in which negative ions are emitted. In the AC type static eliminator of the present embodiment, positive ions and negative ions are emitted from one electrode 31. Therefore, if positive ions and negative ions are switched and emitted in a short period T / 2, positive ions and negative ions are emitted. And easily bind to each other immediately after the negative ions are released. In this case, it is difficult for the positive ions and the negative ions to reach far, and the charge removal range is narrowed.

  As shown in FIG. 2B, when a positive voltage and a negative voltage are alternately applied at a relatively low frequency, positive ions and negative ions are emitted from the discharge unit 3 during a relatively long period T ′. This period T 'is divided into a period T' / 2 in which positive ions are released and a period T '/ 2 in which negative ions are released, and in each period, more positive ions and negative ions than in FIG. Ions are released. As described above, if the period T ′ / 2 in which the positive ions and the negative ions are respectively released is long, it is difficult to bond the positive ions and the negative ions to each other immediately after the positive ions and the negative ions are released. This makes it easier to extend the range of static elimination.

3. Conventional static elimination FIG. 3 is a diagram for explaining control of a voltage applied to the discharge unit 3 at the time of conventional static elimination. FIG. 4 is a diagram showing a change over time of the surface potential of the measurement target W when static electricity of the measurement target W is removed by conventional static elimination.

  At the time of the conventional static elimination, as shown in FIG. 3, the voltage applied to the discharge unit 3 is alternately switched to a positive voltage and a negative voltage at a constant cycle. The absolute values of the applied positive voltage and negative voltage are the same, for example, the positive voltage is 8 kV and the negative voltage is -8 kV.

  In this case, the positive ions and the negative ions are easily bonded to each other immediately after being released, and the positive ions and the negative ions are hard to reach far. Therefore, as shown in FIG. 4, it takes a relatively long time A until the surface potential of the measurement target W is sufficiently lowered. Then, even after the surface potential of the measurement object W is sufficiently lowered, the positive ions and the negative ions are continuously and alternately emitted, so that the ion balance fluctuates. The surface potential changes periodically to a positive potential and a negative potential.

4. FIG. 5 is a diagram for explaining control of a voltage applied to the discharge unit 3 at the time of static elimination in the present embodiment. FIG. 6 is a diagram illustrating a change with time of the surface potential of the measurement target W when static electricity of the measurement target W is removed by static elimination in the present embodiment.

  As shown in FIG. 5, the static elimination time according to the present embodiment includes a time (first static elimination time T1) in which a positive voltage and a negative voltage are alternately applied to the discharge unit 3 at a relatively low frequency (first frequency). The period is divided into a period (second discharging time T2) in which a positive voltage and a negative voltage are alternately applied to the discharge unit 3 at a relatively high frequency (second frequency). The first frequency is lower than the frequency at the time of the conventional static elimination shown in FIG. 3 (for example, the cycle is twice), and the second frequency is higher than the frequency at the time of the conventional static elimination shown in FIG. 1/3). In the first static elimination time T1 and the second static elimination time T2, the absolute values of the applied positive voltage and negative voltage are the same, for example, the positive voltage is 8 kV and the negative voltage is −8 kV.

  The first frequency is, for example, 50 to 500 Hz. The second frequency is, for example, 100 to 1000 Hz. However, the first frequency and the second frequency are not limited to the above values.

  The first charge elimination time T1 and the second charge elimination time T2 are determined by the charge elimination time determination unit 62. For example, if the neutralization time for which the setting is received by the setting receiving unit 61 is 5 sec, the first static elimination time T1 is set to 4 sec, and the second static elimination time is calculated by performing a calculation based on a predetermined ratio with respect to the neutralization time. T2 is determined to be 1 second. In this example, the first charge elimination time T1 is longer than the second charge elimination time T2. However, the present invention is not limited to this. The second charge elimination time T2 may be longer than the first charge elimination time T1.

  In the present embodiment, after the positive voltage and the negative voltage are alternately applied to the discharging unit 3 at the first frequency during the first discharging time T1, the positive voltage and the negative voltage are applied to the discharging unit 3 during the second discharging time T2. The voltage is alternately applied at a second frequency higher than the first frequency. Thus, positive ions and negative ions are emitted from the discharge unit 3 during the set charge elimination time (T1 + T2).

  In this case, during the first static elimination time T1 in which the positive voltage and the negative voltage are alternately applied to the discharge unit 3 at the relatively low first frequency, the positive ions and the negative ions are not easily combined with each other immediately after being released, and the positive ions are hardly combined. It is easy for ions and negative ions to reach far. Therefore, as shown in FIG. 6, the surface potential of the measuring object W can be sufficiently reduced in a relatively short time B.

  During the second static elimination time T2 in which a positive voltage and a negative voltage are alternately applied to the discharge unit 3 at a relatively high second frequency thereafter, the fluctuation of the ion balance is smaller than that of the conventional static elimination (see FIG. 4). can do. Thereby, after performing static elimination over a wide range in a short time during the first static elimination time T1, it is possible to perform static elimination while suppressing fluctuations in ion balance during the second static elimination time T2. It is possible to remove static electricity. As a result, the mass of the measuring object W can be measured with higher accuracy.

5. FIG. 7 is a flowchart illustrating an example of control by the control unit 6 when measuring the mass of the measurement target W. After placing the measurement target object W on the weighing dish 1, the user operates the operation unit 4 to set the static elimination time. When the charge elimination time is set (Yes in step S101), the first charge elimination time T1 and the second charge elimination time T2 are determined by performing a calculation based on a predetermined ratio with respect to the charge elimination time. (Step S102).

  After the first static elimination time T1 and the second static elimination time T2 are determined, when the user operates the operation unit 4 to start static elimination (Yes in step S103), the display unit 5 indicates that static elimination is being performed. While being displayed (step S104), the control of the discharge unit 3 is performed to start the charge elimination (step S105). The measurement of the mass of the measurement object W is performed during the charge elimination, but the measurement result is not displayed on the display unit 5 during the charge elimination.

  Thereafter, when the set static elimination time (the first static elimination time T1 and the second static elimination time T2) elapses (Yes in step S106), the control of the discharge unit 3 ends, and the measurement result of the mass of the measuring object W is displayed. It is displayed on the unit 5 (step S107). At this time, the display indicating that the charge is being removed is deleted from the display unit 5.

6. Modification In the above embodiment, the case where the static eliminator according to the present invention is applied to an electronic balance has been described. However, the present invention is not limited to such a configuration, and the static eliminator according to the present invention can be applied to devices other than the electronic balance. Further, the static eliminator according to the present invention is not limited to the configuration incorporated in the device, and may be configured as a single static eliminator.

REFERENCE SIGNS LIST 1 weighing dish 2 load detection unit 3 discharge unit 4 operation unit 5 display unit 6 control unit 8 weighing room 9 main body 31 electrode 61 setting reception unit 62 static elimination time determination unit 63 static elimination control unit 64 display processing unit T1 first static elimination time T2 2 Static elimination time

Claims (2)

A discharge unit that emits positive ions and negative ions,
A setting reception unit that receives the setting of the static elimination time;
By performing an operation based on a predetermined ratio with respect to the set static elimination time, a first static elimination time in which a positive voltage and a negative voltage are alternately applied to the discharge unit at a first frequency, and a frequency higher than the first frequency. A static elimination time determining unit that determines a second static elimination time for alternately applying a positive voltage and a negative voltage to the discharge unit at a high second frequency;
A positive voltage and a negative voltage are alternately applied to the discharge unit at the first frequency during the first charge elimination time, and then a positive voltage and a negative voltage are applied to the discharge unit during the second charge elimination time. A static eliminator comprising: a static elimination controller configured to discharge positive ions and negative ions from the discharge unit by alternately applying a frequency. A static eliminator according to claim 1,
A main body in which a weighing chamber from which positive ions and negative ions are released from the static eliminator,
An electronic balance, comprising: a weighing dish provided in the weighing chamber, on which an object to be measured is placed.

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