JP6794045B2 - Electromagnetic balanced weight sensor - Google Patents

Description

The present invention relates to an electromagnetically balanced weight sensor.

Conventionally, there is a weighing device such as an electronic balance that uses an electromagnetic equilibrium type weight sensor (see, for example, Patent Document 1).

In this electromagnetic equilibrium type weight sensor, a reverbal mechanism composed of an elastic body, a lever that is displaced in conjunction with the displacement of a movable part of the reverbal mechanism, a displacement detecting means for detecting the displacement of the lever, and a lever in an equilibrium state ( Some have an electromagnetic force generator (coil, magnet, etc.) that returns the displacement to 0). Here, in the electromagnetic force generator, a coil is provided in a magnetic circuit that generates a static magnetic field, and the coil is attached to the lever so as to be displaced together with the lever. Then, when a load is applied to the moving part of the reverbal mechanism, a current is passed through the coil of the electromagnetic force generator so that the displacement of the lever becomes 0, and based on the current value when the displacement of the lever becomes 0. It is configured to calculate the magnitude of the load (mass value of the object to be measured).

Japanese Patent No. 4035724

In the electromagnetic equilibrium type weight sensor as described above, the displacement detecting means for detecting the displacement of the lever is configured by using a light emitting element and a light receiving element arranged in the vicinity of the lever. Since such a light emitting element and a light receiving element generate heat, if the heat affects the magnetic field of the electromagnetic force generator, it causes a measurement error and adversely affects the measurement accuracy.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electromagnetically balanced weight sensor capable of improving weighing accuracy.

In order to achieve the above object, the electromagnetic equilibrium weight sensor according to an embodiment of the present invention is interlocked with a displacement detection unit that detects the displacement of the reverbal mechanism and the displacement of the reverbal mechanism in a magnetic circuit that generates a static magnetic field. The displacement detecting unit is provided with an electromagnetic force generator in which a current is passed through the coil so that the displacement detected by the displacement detecting unit approaches 0, and the displacement detecting unit is provided with the reversal mechanism. A light passing path that is displaced in conjunction with the displacement of the light emitting element, a light emitting element, a light receiving element that is emitted from the light emitting element and incident with light that has passed through the light passing path, and one end thereof is connected to the light emitting element. A light emitting side optical fiber that propagates light emitted from a light emitting element and emits light from the other end to the light passage path, and one end connected to the light receiving element, emitted from the light emitting element, and passed through the light passage path. One or both of the light receiving side optical fibers that incident and propagate light from the other end and incident on the light receiving element, and a displacement calculation unit that obtains the displacement of the reverbal mechanism based on the amount of light incident on the light receiving element. have.

According to this configuration, by using either one or both of the light emitting side optical fiber and the light receiving side optical fiber, the light emitting element, the light receiving element, or both can be arranged away from the electromagnetic force generator. Therefore, it is possible to eliminate the influence of the heat generated by the light emitting element and the light receiving element on the magnetic field of the electromagnetic force generator, suppress the measurement error caused by the heat generation, and improve the measurement accuracy.

A displacement member in which the displacement of the reverbal mechanism appears at the tip portion is further provided, and the light passage path is a through hole provided through the tip portion of the displacement member in a direction intersecting the direction in which the tip portion is displaced. The light receiving side optical fiber and the light receiving element are provided so as to correspond to each other, and the two light receiving side optical fibers are arranged adjacent to each other side by side in the direction in which the tip portion of the displacement member is displaced. The displacement calculation unit may be configured to obtain the displacement appearing at the tip portion based on the difference in the amount of light incident on the two light receiving elements.

According to this configuration, by providing two light receiving side optical fibers and two light receiving elements, it is possible to obtain the displacement appearing at the tip portion of the displacement member based on the difference in the amount of light incident on each light receiving element. Since the displacement direction can be easily determined, it becomes easy to obtain the current value and the direction of the current flowing through the coil.

A load calculation unit that calculates the magnitude of the load applied to the reverbal mechanism based on the current value flowing through the coil when the displacement detected by the displacement detection unit is 0 or substantially 0, and the reverbal mechanism. A temperature sensor for measuring the ambient temperature or the temperature of the displacement mechanism itself may be further provided, and the load calculation unit may be configured to correct the magnitude of the load based on the temperature measured by the temperature sensor. ..

According to this configuration, by correcting the magnitude of the load based on the temperature measured by the temperature sensor, it is possible to suppress the measurement error caused by the temperature characteristics of the reverbal mechanism and the like.

The present invention has an effect that it is possible to provide an electromagnetically balanced weight sensor having the configuration described above and capable of improving the weighing accuracy.

FIG. 1 is a front view of an electromagnetically balanced weight sensor according to an embodiment of the present invention. FIG. 2A is a perspective view of the electromagnetically balanced weight sensor of FIG. 1, and FIG. 2B is an enlarged perspective view of a displacement detection portion of the electromagnetically balanced weight sensor and a portion in the vicinity thereof. 2 (C) is a schematic plan view of the displacement detection unit of the electromagnetic equilibrium type weight sensor and its vicinity as viewed from above. FIG. 3A is a schematic cross-sectional view of the electromagnetic force generator, FIG. 3B is an external perspective view of the electromagnetic force generator, and FIG. 3C is a yoke of the electromagnetic force generator. It is a figure which shows the state which the lid is removed. FIG. 4A is a perspective view of the electromagnetic force generator of another example, and FIG. 4B is a side view of the electromagnetic force generator of another example.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and duplicate description thereof will be omitted. Moreover, the present invention is not limited to the following embodiments.

(Embodiment)
FIG. 1 is a front view of an electromagnetically balanced weight sensor according to an embodiment of the present invention. FIG. 2A is a perspective view of the electromagnetically balanced weight sensor of FIG. 1, and FIG. 2B is an enlarged perspective view of a displacement detection portion of the electromagnetically balanced weight sensor and a portion in the vicinity thereof. 2 (C) is a schematic plan view of the displacement detection unit of the electromagnetic equilibrium type weight sensor and its vicinity as viewed from above.

This electromagnetic equilibrium type weight sensor A is used in a weighing device B such as an electronic balance, and a fixing portion 11 constituting a reverbal mechanism described later is fixed to a stationary member (for example, a base portion B1 of the weighing device B). ) Is fixed by a bolt or the like, and the movable portion 12 is fixed to the mounting portion B3 that supports the object to be placed portion B4 such as a plate by the bolt or the like. For example, when the object to be measured is placed on the object to be placed B4, a load is applied to the movable portion 12.

The electromagnetic balance type weight sensor A includes a mechanism 1, a displacement detection unit 2, an electromagnetic force generator 3, a stopper mechanism 4, and a controller 5.

The controller 5 is installed inside the weighing device B (for example, the base portion B1) away from the mechanism 1, and is configured to include, for example, a microcontroller or the like, and controls the entire weighing device B. The controller 5 is connected to the light emitting element 21a and the light receiving elements 22a and 22b of the displacement detection unit 2, and controls the driving (light emission) of the light emitting element 21a and corresponds to the amount of light received from each of the light receiving elements 22a and 22b. Enter the current to be Further, the controller 5 is connected to the coil 37 of the electromagnetic force generator 3, and a current is passed through the coil 37. Further, the controller 5 is connected to a display unit (not shown) of the weighing device B that displays the mass value of the weighted object mounted on the weighted object mounting unit B4, and the display unit is connected to the display unit (not shown). Control.

The mechanism body 1 includes a reverbal mechanism 1R and a displacement amplification mechanism 1A (lever mechanism 1L and arm portion 1B).

The reverbal mechanism 1R connects the fixed portion 11 that is statically fixed, the movable portion 12 that is horizontally separated from the fixed portion 11 and is arranged in parallel and is loaded with a load, and the fixed portion 11 and the movable portion 12, and connects each other. It includes upper and lower beam portions 13 and 14 arranged in parallel. The upper portions of the fixed portion 11 and the movable portion 12 are connected to each other by the upper beam portion 13 via the thin-walled portions 13a and 13b, and the lower portions thereof are connected to each other by the lower beam portion 14 via the thin-walled portions 14a and 14b. ing. In such a reverbal mechanism 1R, as is well known, when a load is applied to the movable portion 12, the movable portion 12 is lowered with respect to the fixed portion 11 while maintaining its posture (a state parallel to the fixed portion 11). It is designed to be displaced (vertically). The vertical length of the reverbal mechanism 1R is longer than the length in the direction in which the fixed portion 11 and the movable portion 12 are separated (longitudinal direction of the beam portions 13 and 14), and as shown in FIG. It has a vertically long shape that is approximately rectangular and long in the vertical direction.

The mechanism body 1 is provided with a displacement amplification mechanism 1A having a lever mechanism 1L and an arm portion (displacement member) 1B inside the reverbal mechanism 1R in order to amplify the vertical displacement of the movable portion 12. ..

In order to form the displacement amplification mechanism 1A, particularly the lever mechanism 1L, the mechanism body 1 has protrusions 11a and 11b protruding inward from the fixed portion 11 and protrusions 12a protruding inward from the movable portion 12. It is provided. Then, in order to form the lever mechanism 1L, first and second lever portions 16 and 18 extending in the horizontal direction and connecting portions 15 and 17 extending in the vertical direction are provided to form the arm portion 1B. The arm portion constituent member 19 of the above is provided.

The lever mechanism 1L has a first lever portion 16 and a second lever portion 18. One end of the first lever portion 16 is connected to the protruding portion 12a on the movable portion 12 side by a connecting portion 15 having narrowed portions 15a and 15b formed at both ends, and a portion slightly closer to the fixed portion 11 side than the one end is formed. It is connected to the protruding portion 11a on the fixing portion 11 side via the narrowed portion f1 that serves as the fulcrum. As a result, the first lever portion 16 is swingably connected to the fixed portion 11 via the narrowed portion f1, one end is connected to the movable portion 12 via the connecting portion 15, and the other end is movable. The vertical displacement of the portion 12 is amplified and appears.

The second lever portion 18 is arranged below the first lever portion 16. The portion of the second lever 18 near the fixing portion 11 is connected to the lower portion of the other end of the first lever 16 by a connecting portion 17 having narrowed portions 17a and 17b formed at both ends, and further near the fixing portion 11. Is connected to the protruding portion 11b on the fixed portion 11 side via the narrowed portion f2 that serves as the fulcrum of the lever. As a result, the second lever portion 18 is swingably connected to the fixed portion 11 via the narrowed portion f2, and one end is connected to the other end of the first lever portion 16 via the connecting portion 17. , The vertical displacement of the other end of the first lever 16 is amplified and appears at the other end.

An arm portion component 19 extending downward is connected to a portion of the second lever portion 18 near the movable portion 12 with a bolt. The arm portion component 19 is attached to the second lever portion 18 and extends parallel to the second lever portion 18 toward the movable portion 12 side, and the lever attachment portion 19x is below the end portion of the lever attachment portion 19x on the movable portion 12 side. It has an arm body portion 19v extending in the direction and an arm tip portion 19h extending in the horizontal direction from the lower end portion of the arm body portion 19v toward the fixing portion 11.

The arm portion component 19 constitutes an arm portion 1B that converts the vertical displacement of the movable portion 12 amplified by the lever mechanism 1L into a substantially horizontal displacement and amplifies it. The portion of the mechanism 1 other than the arm component 19 is composed of a single component, and the width (thickness) in the direction of arrow e in FIG. 2A is the same.

It may be considered that the lever mounting portion 19x of the arm portion constituent member 19 is included in the second lever portion 18, and the arm portion 1B is formed by the arm main body portion 19v and the arm tip portion 19h.

Further, in this example, only the arm portion constituent member 19 is configured as a separate component in the mechanism body 1, but the entire mechanism body 1 including the arm portion constituent member 19 may be configured as a single component. Good. The mechanism 1 is made of, for example, an aluminum alloy.

As described above, when a load is applied to the movable portion 12, the movable portion 12 is displaced downward. As a result, one end of the connecting portion 15 and the first lever portion 16 is displaced downward (strictly speaking, displaced in an arc shape) as shown by the arrow a, and the other end of the first lever portion 16 and the connecting portion 17 are displaced. However, as shown by the arrow b, it is largely displaced upward (strictly speaking, it is displaced in an arc shape). Then, the portion of the second lever 18 near the movable portion 12 is displaced more upward (strictly speaking, it is displaced in an arc shape) as shown by the arrow c, and the arm portion component 19 is indicated by the arrow d. As shown, it rotates around the narrowed portion f2, which is the fulcrum of the second lever portion 18, and swings toward the movable portion 12. At this time, the displacement that appears in the portion of the second lever 18 near the movable portion 12 by the arm portion 1B is changed by 90 degrees in the displacement direction and is amplified and appears in the arm tip portion 19h, and the arm tip portion 19h is substantially abbreviated. Displace in the horizontal direction. Although the arrows a to d indicating the displacement directions are shown in large size, the actual displacement is very small.

Then, when the displacement of the arm tip portion 19h is detected by the displacement detecting unit 2, a current flows through the coil 37 of the electromagnetic force generator 3 so that the displacement approaches zero.

As shown in FIGS. 1 and 2, for example, the displacement detection unit 2 is provided on the light emitting unit 21, the light receiving unit 22, the light emitting side optical fiber 23, the light receiving side optical fibers 24 and 25, and the arm tip portion 19h. It has a light passage hole (light passage path) 19a and a displacement calculation unit (function of the controller 5). The light passing hole 19a is displaced together with the arm tip portion 19h in conjunction with the displacement of the reverbal mechanism 1R (displacement of the movable portion 12). Then, the displacement detection unit 2 detects the displacement of the reverbal mechanism 1R by detecting the displacement of the arm tip portion 19h.

The light emitting unit 21 is configured to include, for example, one light emitting element 21a made of an LED or the like, and the light receiving unit 22 is configured to have, for example, two light receiving elements 22a, 22b made of a light emitting diode or the like. .. The light emitting element 21a and the light receiving elements 22a and 22b are attached at least at a location away from the electromagnetic force generator 3 so that the heat generated by them does not affect the magnetic field of the electromagnetic force generator 3.

In this embodiment, the arm tip 19h, which is the displacement detection location, is in the vicinity of the electromagnetic force generator 3, so that the light emitting element 21a and the light receiving elements 22a, 22b are both the arm tip 19h and the electromagnetic force generator 3. It is installed at a position away from. Specifically, these are attached to the substrate of the controller 5 or the base portion B1 or the like in the vicinity thereof. Alternatively, it may be attached near the upper end of the fixing portion 11.

The incident end 23a of the light emitting side optical fiber 23 is connected to the light emitting element 21a of the light emitting unit 21. Further, in the two light receiving side optical fibers 24 and 25, their respective emission ends 24b and 25b are connected to each of the light receiving elements 22a and 22b. Then, the end face of the emission end 23b of the light emitting side optical fiber 23 and the end faces of the incident ends 24a, 25a of the two light receiving side optical fibers 24, 25 face each other with the light passing hole 19a of the arm tip portion 19h interposed therebetween. The emission end 23b side portion of the light emitting side optical fiber 23 and the incident end 24a, 25a side portions of the light receiving side optical fibers 24, 25 are attached to appropriate positions of the attachment member 6 so as to be arranged in the above position. It is fixed. The mounting member 6 is fixed to the fixing portion 11 with bolts.

The light passage hole 19a of the arm tip 19h is a small through hole provided so as to penetrate in a direction intersecting (for example, orthogonal to) the direction in which the arm tip 19h is displaced. The end faces of the incident ends 24a and 25a of the two light receiving side optical fibers 24 and 25 are arranged adjacent to each other side by side in the direction in which the arm tip portion 19h is displaced.

The light emitted from the light emitting element 21a of the light emitting unit 21 propagates through the light emitting side optical fiber 23, further passes through the light passing hole 19a, and further propagates through the light receiving side optical fibers 24 and 25. A signal (hereinafter, referred to as “light receiving signal”) corresponding to the amount of light received by the light receiving elements 22a and 22b and received by the light receiving elements 22a and 22b is input to the controller 5.

Further, a rod-shaped (cylindrical) stopper member 4a for forming the stopper mechanism 4 is fixed to the mounting member 6. The arm tip 19h is provided with a through hole 19b having a diameter slightly larger than the diameter of the stopper member 4a, which penetrates in a direction intersecting (for example, orthogonal to) the direction in which the arm tip 19h is displaced. The stopper member 4a is inserted into the through hole 19b with a gap from the inner surface (wall surface) of the through hole 19b. The stopper mechanism 4 is composed of the through hole 19b of the arm tip 19h and the stopper member 4a. By this stopper mechanism 4, the displacement amount of the arm tip portion 19h is restricted to be equal to or less than the gap between the inner surface of the through hole 19b and the stopper member 4a, so that an excessive load is applied to the movable portion 12 (excessive load). It is possible to prevent damage such as deformation of the mechanism 1 caused by load) or the like. In particular, it is possible to prevent damage such as deformation due to overloading of a portion where a large force is applied, such as a narrow portion f1 and f2 which is a fulcrum of the lever mechanism 1L. The distance (the size of the gap) between the inner surface of the through hole 19b and the stopper member 4a can appropriately suppress the force applied to the narrowed portions f1, f2, etc., which are the fulcrums of the lever mechanism 1L, by using CAE or the like. It can be set to be an interval.

By providing the stopper mechanism 4 at the arm tip 19h at the tip of the displacement amplification mechanism 1A where a larger displacement occurs with respect to the displacement of the reverbal mechanism 1R (displacement of the movable portion 12), a through hole constituting the stopper mechanism 4 is formed. The distance between the inner surface of 19b and the stopper member 4a can be increased, and the stopper mechanism 4 can be easily manufactured. Further, in the stopper mechanism 4, since the stopper member 4a is inserted into the through hole 19b, the stopper function works with respect to the displacement in the forward and reverse directions.

Next, the electromagnetic force generator 3 will be described with reference to FIG. 3 (A) is a schematic cross-sectional view of the electromagnetic force generator 3, FIG. 3 (B) is an external perspective view of the electromagnetic force generator 3, and FIG. 3 (C) is an electromagnetic force generator 3. It is a figure which shows the state which removed the lid 36 of the yoke of.

The electromagnetic force generator 3 includes a magnetic circuit 31 that forms a static magnetic field, and a coil (force coil) 37 that is arranged in the magnetic circuit 31.

The coil 37 is attached to a predetermined position of a portion closer to the tip (lower end) from the central portion of the arm main body portion 19v via a coil mounting bracket 38. The coil mounting bracket 38 is fixed to the arm body 19v with screws 39.

The magnetic circuit 31 is composed of, for example, two magnets (permanent magnets) 32 and 33, a pole piece 34, a yoke 35, and a yoke lid 36. The yoke 35 has a bottom portion having a bottomed cylindrical shape having an open end fixed to the fixing portion 11. The lid 36 of the yoke is made of the same metal as the yoke 35, such as iron, and is fixed to the opening side of the yoke 35.

A magnet 32, a pole piece 34, and a magnet 33 are stacked and fixed to the inner bottom of the yoke 35 in this order. The lid 36 of the yoke is each provided with two through holes 36h for inserting the coil mounting bracket 38. Further, the lid 36 of the yoke is divided into two semi-disc portions 36a and 36b, and the lid 36 (36a, 36b) can be closed after the coil 37 is arranged inside the yoke 35. ..

In this measuring device B, when a load is applied to the movable portion 12 by placing the object to be measured on the object placing portion B4, the movable portion 12 is displaced downward, and the arm tip portion 19h at this time. The displacement of is detected by the displacement detection unit 2. At this time, the controller 5 drives the light emitting element 21a in advance, and always displaces the arm tip 19h based on the difference in the amount of light received by the two light receiving elements 22a and 22b (difference in the light receiving signal). Displacement direction and displacement amount) are obtained (function as a displacement calculation unit of the controller 5).

Then, in order to generate an electromagnetic force that is balanced with the load of the movable portion 12 by the movement of the coil 37 in the opposite direction, the amount of light received by the two light receiving elements 22a and 22b is made equal (of the arm tip portion 19h). A current is passed through the coil 37 by feedback control (PID control) so that the displacement approaches 0). Then, the controller 5 uses a current mass conversion formula to determine the current value flowing through the coil 37 when the amount of light becomes substantially equal (when the displacement approaches 0 or becomes 0), and the object to be measured. Converted to the mass value (magnitude of load) of (function as load calculation unit of controller 5). Then, the mass value is output to a display unit (not shown) of the measuring device B and displayed. The controller 5 stores in advance the above-mentioned current-mass conversion formula, which is a conversion formula for converting the current value flowing through the coil 37 into a mass value, but the current flowing through the coil 37 is converted by a resistor. It may be taken out in the form of a voltage and the taken out voltage may be converted into a mass.

The electromagnetic balance type weight sensor A of the present embodiment uses the light emitting side optical fiber 23 and the light receiving side optical fibers 24 and 25 for the displacement detecting unit 2, and emits light to the light passing hole 19a of the arm tip portion 19h which is the displacement detecting point. Since the light from the light emitting element 21a is emitted through the side optical fiber 23 and the light passing through the light passing hole 19a is received by the light receiving elements 22a and 22b via the light receiving side optical fibers 24 and 25, the light is received by the light receiving elements 22a and 22b. The light emitting element 21a and the light receiving elements 22a and 22b can be arranged away from the electromagnetic force generator 3. Therefore, it is possible to eliminate the influence of the heat generated by the light emitting element 21a and the light receiving elements 22a and 22b on the magnetic field of the electromagnetic force generator 3, suppress the measurement error caused by the heat generation, and improve the measurement accuracy.

Further, in the present embodiment, by providing two light receiving side optical fibers 24 and 25 and two light receiving elements 22a and 22b, the tip of the displacement amplification mechanism 1A is based on the difference in the amount of light incident on the respective light receiving elements 22a and 22b. Since the displacement appearing in the portion (arm tip 19h) can be obtained and the displacement direction can be easily determined, it becomes easy to obtain the current value and the direction of the current flowing through the coil 37. In the present embodiment, when the amount of light received by the light receiving element 22a connected to the light receiving side optical fiber 24 is larger than the amount of light received by the light receiving element 22b connected to the light receiving side optical fiber 25, the tip of the arm The displacement direction of the portion 19h is the direction approaching the movable portion 12, and in the opposite case, the displacement direction of the arm tip portion 19h is the direction away from the movable portion 12.

Instead of the two light receiving side optical fibers 24 and 25 and the light receiving elements 22a and 22b, one light receiving side optical fiber and the light receiving element may be provided. In this case, for example, the end face of the incident end of one light receiving side optical fiber is arranged so as to face the end face of the emitting end 23b of the light emitting side optical fiber 23 with the arm tip 19h interposed therebetween. Then, instead of the light passing hole 19a, the light receiving side optical fiber is provided to the arm tip 19h according to the direction in which the arm tip 19h is displaced (whether the direction approaches the movable portion 12 or the opposite direction). An optical passage path may be provided so that the amount of light that propagates and is received by the light receiving element increases or decreases.

For example, as a light passage path, a rectangular through hole long in the displacement direction is provided in the arm tip portion 19h. When the displacement of the arm tip 19h is 0, the light emitted from the light emitting side optical fiber 23 passes through a substantially half region of the rectangle of the light passage path, and when the light is displaced in the direction approaching the movable portion 12, the light is emitted. By also shifting the passage path, the area through which light passes in the light passage path increases (or decreases), and when the light passage path is displaced in the direction approaching the movable portion 12, the light passage path is also displaced, so that the inside of the light passage path is also displaced. The light passage path may be provided so that the area through which light passes is reduced (or increased).

Further, the characteristics of the mechanical body 1 including the reverbal mechanism 1R change depending on the temperature of its constituent member (elastic body). Therefore, a temperature sensor (for example, a thermistor) for measuring the ambient temperature of the reverbal mechanism 1R or the temperature of the reverbal mechanism 1R itself is provided, and the controller 5 calculates based on the current value of the coil 37 based on the measured temperature. The mass value of the object to be measured may be corrected. For example, the corrected mass value may be calculated using a predetermined calculation formula for temperature correction. By correcting in this way, it is possible to suppress the measurement error caused by the temperature characteristics of the reverbal mechanism 1R and the like.

Further, in the present embodiment, the displacement amplification mechanism 1A is composed of a lever mechanism 1L and an arm portion 1B, the arm portion 1B is provided so as to extend downward from the lever mechanism 1L, and the coil 37 of the electromagnetic force generator 3 is an arm. Since it is configured to be displaced in conjunction with the portion 1B, the arm portion 1B and the electromagnetic force generator 3 are arranged below the lever mechanism 1L to form a long structure in the vertical direction, and the occupied area (installation area) can be reduced. It can also be used for weighing devices with a small installation space.

Further, in the present embodiment, the lever mechanism 1L is configured to have two lever portions 16 and 18, but it may have one or more lever portions. For example, the lever mechanism 1L may have only one lever portion 16 and the arm portion 1B may be connected to the lever portion 16. When the lever mechanism 1L has two lever portions 16 and 18, the displacement detection accuracy can be improved and the displacement can be brought closer to 0 as compared with the case where only one lever portion 16 is provided. The current flowing through the coil 37 can be reduced.

Further, since the reverbal mechanism 1R has a vertically long shape that is long in the vertical direction, an eccentric load is applied to the movable portion 12, for example, because the object to be measured is unevenly placed on one end of the object to be placed B4. It is possible to improve the twist resistance at the time.

In the present embodiment, the reverbal mechanism 1R has a vertically long shape, and a displacement amplification mechanism 1A (lever mechanism 1L and arm portion 1B) or the like is provided inside the reverbal mechanism 1R, but the displacement amplification mechanism is not limited to this configuration. All or part of 1A may be outside the displacement mechanism 1R. For example, the reverbal mechanism 1R may have a horizontally long shape, and a displacement amplification mechanism 1A, a displacement detection unit 2, an electromagnetic force generator 3, a stopper mechanism 4, and the like may be provided below the lower beam portion 14 of the reverbal mechanism 1R. ..

Further, the displacement amplification mechanism 1A may be configured to be provided with an extended portion in which the tip portion of the lever mechanism 1L is extended in the horizontal direction instead of the arm portion 1B extending downward. In this case, an electromagnetic force generator 3 is provided for the stretched portion, a displacement detecting portion 2 is provided for detecting the displacement of the tip portion of the stretched portion, and a stopper mechanism 4 is provided for the tip portion of the stretched portion. do it.

Further, the electromagnetic force generator 3 may have another configuration, for example, a magnetic circuit may be configured by using one magnet. FIG. 4A is a perspective view of the electromagnetic force generator 3A of another example, and FIG. 4B is a side view of the electromagnetic force generator 3A of another example. In FIG. 4, the parts corresponding to those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. The electromagnetic force generator 3A has a configuration in which the magnet 33 and the lid 36 of the yoke are removed from the electromagnetic force generator 3 described above. In this case, the magnetic circuit is composed of a magnet 32, a pole piece 34, and a yoke 35.

The electromagnetic equilibrium type weight sensor A in the present embodiment can be used for a weighing device such as a digital precision balance such as the above-mentioned weighing device B, and for example, each of a combination scale having a plurality of weighing hoppers. It can also be used for weighing hoppers and the like. For example, in the case of a weighing hopper, the hopper that temporarily holds and discharges the object to be measured is connected and supported by the movable portion 12 of the reverbal mechanism 1R.

From the above description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed only as an example and is provided for the purpose of teaching those skilled in the art the best aspects of carrying out the present invention. The details of its structure and / or function can be substantially changed without departing from the spirit of the present invention.

The present invention is useful as an electromagnetically balanced weight sensor or the like that can improve weighing accuracy.

1R Reverbal mechanism 1A Displacement amplification mechanism 1L Lever mechanism 1B Arm part 2 Displacement detection part 3, 3A Electromagnetic force generator 4 Stopper mechanism 4a Stopper member 5 Controller 11 Fixed part 12 Movable part 13, 14 Beam part 15, 17 Connecting part 16 1st lever 18 2nd lever 19 Arm component 19v Arm body 19h Arm tip 19a Light passage hole 19b Through hole 21a Light emitting element 22a, 22b Light receiving element 23 Light emitting side optical fiber 24, 25 Light receiving side optical fiber 31 Magnetic circuit 37 coil

Claims (3)

A displacement detector that detects the displacement of the reverbal mechanism,
A coil that is displaced in conjunction with the displacement of the reverbal mechanism is provided in a magnetic circuit that generates a static magnetic field, and an electromagnetic force is applied through the coil so that the displacement detected by the displacement detection unit approaches zero. With the generator
With
The displacement detection unit
An optical passage that is displaced in conjunction with the displacement of the reverbal mechanism
Light emitting element and
A light receiving element that emits light emitted from the light emitting element and is incident with light that has passed through the light passage path.
One end is connected to the light emitting element, the light emitting side optical fiber that propagates the light emitted from the light emitting element and is emitted from the other end to the light passing path, and one end is connected to the light receiving element, and the light emitting element One or both of the light receiving side optical fibers that are emitted from the light and propagate through the other end of the light passing path and are incident on the light receiving element.
And have a displacement calculation unit that calculates a displacement of the Roberval mechanism based on the amount of light incident on the light receiving element,
A lever mechanism provided inside the reverbal mechanism and amplifying the vertical displacement of the reverbal mechanism,
An arm body portion provided inside the reverbal mechanism and connected to the lever mechanism and extending downward, and an arm portion having an arm tip portion extending horizontally from the lower end portion of the arm body portion.
With more
The electromagnetic force generator is arranged inside the reverbal mechanism and below the lever mechanism.
The arm tip portion is arranged below the electromagnetic force generator and is provided with the light passage path.
Electromagnetic balanced weight sensor. Before Symbol light passage is a through hole which the arm tip to the arm tip portion is provided through in a direction intersecting the direction of displacement,
Two light-receiving optical fibers and two light-receiving elements are provided.
The two light-receiving optical fibers are arranged adjacent to each other side by side in the direction in which the tip of the arm is displaced.
The displacement calculation unit is configured to obtain the displacement that appears at the tip of the arm based on the difference in the amount of light incident on the two light receiving elements.
The electromagnetically balanced weight sensor according to claim 1. A load calculation unit that calculates the magnitude of the load applied to the reverbal mechanism based on the current value flowing through the coil when the displacement detected by the displacement detection unit is 0 or substantially 0.
Further provided with a temperature sensor for measuring the ambient temperature of the reverbal mechanism or the temperature of the reverbal mechanism itself.
The load calculation unit
It is configured to correct the magnitude of the load based on the temperature measured by the temperature sensor.
The electromagnetically balanced weight sensor according to claim 1 or 2.

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