JP5285350B2 - Weight measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weight measuring apparatus capable of reducing a power consumption consumed for determining whether an object to be measured is put on a mount section in its standby state, while maintaining its convenience. <P>SOLUTION: The weight measuring apparatus which automatically starts a weight measurement when the object to be measured is put on the mount section, includes: a first weight detecting means for detecting whether the object to be measured is put on the mount section; a second weight detecting means for detecting the weight of the object to be measured; and a control means for obtaining the weight of the object to be measured, based on an output value from the second weight detecting means, when making the determination that the object to be measured is put on the mount section, based on an output value from the first weight detecting means. The power consumption of the first weight detecting means is lower than that of the second weight detecting means. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention mainly relates to a weight measurement device, and more particularly to a weight measurement device that automatically starts measuring the weight of a measurement target when the measurement target is placed on a mounting portion of the weight measurement device.

  Conventionally, in view of user convenience, a type of weight measuring device that automatically starts weight measurement when a measurement target is placed on a placement unit has been used. Such a weight measuring device that automatically starts measuring the weight when the object to be measured is placed on the placement unit is such that the object to be measured is placed on the placement unit in a standby state where the weight measurement device is not used. Since it is necessary to determine whether or not there is power, the power required for the determination is always consumed or at predetermined time intervals.

  Accordingly, various proposals have been made to reduce the power consumption of the weight measuring device. For example, there is a weight measuring device that performs an update of the zero point in a standby state every predetermined time, and includes an operation switch that turns on the weight measuring device when a measurement target is placed on the mounting portion. This operation switch has a coil spring and is mechanically operated. When no load is applied to the mounting portion, the switching contact is opened by the repulsive force of the coil spring, the weight measuring device is turned off, and the mounting portion is turned on. When the object to be measured is placed and a load against the repulsive force of the coil spring is applied, the switching contact is closed and the weight measuring device is turned on (for example, Patent Document 1).

JP-A 62-126318

  Even in the conventional weight measuring apparatus as described above, it is possible to reduce power consumption. However, since it is necessary to provide a mechanical operation switch on the leg portion to determine whether the object to be measured is placed on the placement portion, it is difficult to reduce the thickness of the weight measuring device and increase the number of parts. It is also assumed.

  Here, in the weight measuring device, generally, when receiving a load, a strain generating body that deforms according to the load, and depending on deformation (expansion / contraction) of the strain generating part that is attached to the strain generating part of the strain generating body. A load cell including a strain gauge whose output value changes is provided. The weight measuring device measures the weight of the object to be measured based on the difference between the output value of the load cell when the load is not applied (so-called zero point) and the output value when the load is applied. ing.

  Therefore, the circuit for measuring the weight of the object to be measured using the load cell is made to function even in a standby state where the weight measuring device is not used, and it is determined whether or not a load is applied to the mounting portion. However, in order to determine whether or not the object to be measured is placed on the placement unit, the power required for the determination is always consumed or at predetermined time intervals. Therefore, there is a problem in that the power to be measured is actually placed on the mounting portion, and the power consumed in the measurement state for measuring the weight of the measurement target is not much different from the power consumed in the standby state. .

  Therefore, the present invention is a further improvement of the conventional weight measuring device, and realizes convenience, simplification of configuration, and thinning of the weight measuring device, while the measurement target is placed on the mounting portion in the standby state. An object of the present invention is to provide a weight measuring apparatus that can also realize reduction of power consumption for determining whether or not there is.

The weight measuring device of the present invention for solving the above problem is a weight measuring device that automatically starts measuring the weight when the object to be measured is placed on the placement unit, and the object to be measured is placed on the placement unit. Based on output values from the first weight detection means for detecting whether or not it is mounted, the second weight detection means for detecting the weight of the object to be measured, and the first weight detection means. Control means for acquiring the weight of the object to be measured based on an output value from the second weight detection means when it is determined that the object to be measured is placed on the mounting portion, and the first weight The detection means is a load cell in which a first strain gauge is affixed to a strain body, and the second weight detection means is a load cell in which a second strain gauge is affixed to the strain body, The resistance value of the first strain gauge is higher than the resistance value of the second strain gauge. Power consumed by the first weight detecting means being lower than the power consumed by the second weight detecting means.

  Further, the first strain gauge and the second strain gauge in the weight measuring device of the present invention are affixed to the same strain body.

In the weight measuring device of the present invention, the strain body is formed in a bilaterally symmetric shape, and includes a strain section that is disposed in the center of the strain body and extends parallel to the symmetry axis. The gauge is affixed to one of the upper and lower surfaces of the strain-generating portion, and the second strain gauge is affixed to the opposite surface of the strain-generating portion. The weight measuring apparatus of the present invention further includes a switching unit that switches between the first weight detection unit and the second weight detection unit, and the control unit uses the switching unit to detect the first weight detection unit. The means and the second weight detection means are selectively functioned.

  In addition, when the control unit in the weight measuring device of the present invention determines that the measurement target is not placed on the placement unit based on an output value from the first weight detection unit, a predetermined zero point update is performed. It is determined whether or not the time interval has elapsed, and when the predetermined time interval has elapsed, the zero point of the second weight detection unit is updated.

  According to the present invention, the first weight detection means for determining whether or not the measurement target is placed on the mounting portion, the second weight detection means for measuring the weight of the measurement target, And the first weight detecting means is a weight measuring device configured to consume less power than the second weight detecting means. This eliminates the need to mechanically turn on / off the weight measuring device, simplify the configuration and reduce the weight of the weight measuring device, and maintain the convenience for the user of the weight measuring device while waiting. The power consumption for determining whether or not the object to be measured is placed on the placement portion can be reduced.

  Hereinafter, an embodiment in which a weight measuring device according to the present invention is applied to a so-called step-on type weight scale that measures the weight (body weight) of a measurement subject (user) as a measurement target will be described with reference to the drawings. I will explain. 1 is an exploded perspective view showing a configuration of a weight scale according to the embodiment, FIG. 2A is a partially enlarged view showing a portion II of FIG. 1 of the load cell of the weight scale according to the embodiment, and FIG. Fig. 3 is a diagram showing the back surface of Fig. 2 (a), Fig. 3 is a side view showing a part of the load cell viewed from the direction of arrow III in Fig. 2 (a), and Fig. 4 is a control of the weight scale according to the embodiment. FIG. 5 is a diagram showing an example of a control flow of the scale according to the embodiment. FIG. 5 is a diagram showing a block diagram showing the system, a plan view and a rear view of the load cell. In the present invention, the standby state refers to a state in which the weight measuring device of the present invention is not used to measure the weight of the object to be measured, and the measurement state refers to the weight measuring device of the present invention of the object to be measured. The state that can be used to measure the weight.

  The weight scale 1 mainly detects a first weight detection unit 38 as a first weight detection means for detecting whether or not the person to be measured is placed on the placement unit 1a, and the weight of the person to be measured. When it is determined that the person to be measured is placed on the placement portion 1a based on the output value from the second weight detection portion 39 and the first weight detection portion 38 as the second weight detection means for And a control circuit 31 as control means for acquiring the weight of the object to be measured based on the output value from the second weight detection unit 39.

  Each component will be described in detail below. As shown in FIG. 1, the weight scale 1 is formed in a substantially box shape, and includes a leg portion 65 that protrudes from the back side of the weight scale 1 (the back side of the bottom plate member 20 b). On the upper surface of the weight scale 1, a placement unit 1 a on which a measurement subject is placed, a display unit 21, and an operation unit 22 are provided. The weight scale 1 includes a first weight detection unit 38, a second weight detection unit 39, a control circuit 31, a storage unit 33, a power supply unit 34, a switching circuit 35, and a time measuring unit 36. , Multiplexers 82 and 83.

  The weight scale 1 includes a cover member 20a between a cover member 20a formed by molding a resin (for example, ABS resin (acrylonitrile / butadiene / styrene copolymer), glass) and the like, and a metal bottom plate member 20b. A substantially plate-like frame member 40 is interposed so as to be in contact with the back surface side of the cover member, and the cover member 20a and the bottom plate member 20b are joined together to form a substantially box-like appearance as a whole.

  As shown in FIG. 4, the control circuit 31 is electrically connected to the display unit 21, the operation unit 22, the storage unit 33, the switching circuit 35, and the time measuring unit 36, and controls each function. Further, the control circuit 31 is configured such that either the multiplexer 82 and the first weight detection unit 38 or the multiplexer 83 and the second weight detection unit 39 are connected via the switching circuit 35. Based on the output value from the first weight detector 38 or the second weight detector 39, the weight can be calculated according to a predetermined program. Further, display control of the display unit 21, data read / write processing to the storage unit 33, and the like are performed. In the present embodiment, supply detection circuits 80 and 81 are provided for the load cells of the first weight detection unit 38 and the second weight detection unit 39 as described later. The control circuit 31 may serve as the function 81. The same applies to other examples described later.

  In order to selectively connect the first weight detection unit 38 or the second weight detection unit 39 to the control circuit 31, the switching circuit 35 includes the control circuit 31, the first weight detection unit 38, and the first weight detection unit 38. 2 weight detection units 39. Therefore, when the switching circuit 35 receives a control signal from the control circuit 31, the switching circuit 35 is connected to either the first weight detection unit 38 or the second weight detection unit 39 in response to the control signal. Set to

  The display unit 21 is data display means (display means) for displaying data sent from the control circuit 31, and mainly displays the weight of the person to be measured. As an example, the display unit 21 may employ a liquid crystal display such as a full-dot LCD (Liquid Crystal Display), or the display unit 21 and the operation unit 22 may be a liquid crystal display having a touch panel function, for example. You may comprise integrally as a panel. The operation unit 22 is data input means (input means) for performing initial setting of the weight scale 1 and the like. In the present embodiment, as an example, three buttons are configured on the front side of the display unit 21 of the scale 1, but the number, shape, operation method, and arrangement position are not particularly limited thereto, and the operation unit 22 is not limited thereto. It is good also as a structure which does not provide.

  The memory | storage part 33 is a memory | storage means comprised by ROM (non-volatile memory (Read Only Memory)), RAM (volatile memory (Random Access Memory)), etc., and memorize | stores various data. Examples of the data include various data and programs used in processing by the control circuit 31 and acquired biological information for each person to be measured. The control circuit 31 reads and writes data as described above.

  As the power supply unit 34, a battery or an external power supply that supplies power for operating the scale 1 can be used. In the weight scale 1 of the embodiment, in a standby state, the supply of electric power required for the weight measurement process described later is stopped, so-called zero point update processing, or determination of whether or not the subject is placed on the weight scale 1. Only power necessary for processing is supplied. On the other hand, when it is determined that the person to be measured has been placed and the weight scale 1 is switched to the measurement state, power required for the weight measurement process described later is supplied. For this reason, in the standby state, for example, the display unit 21 is not energized and nothing is displayed.

  The time measuring unit 36 measures the passage of a predetermined time and determines whether or not the predetermined time has passed. In the present embodiment, the time measuring unit 36 is an independent component, but is configured to be integrated with the control circuit 31 as a time measuring circuit, and the control circuit 31 itself measures the elapse of a predetermined time or elapses of the predetermined time. You may make it judge whether it is doing.

  The first weight detection unit 38 and the second weight detection unit 39, which are weight detection means, can measure the weight (body weight) of the person to be measured placed on the placement unit 1a of the weight scale 1. . For example, a strain gauge made of a metal member that deforms in response to a load, and a strain gauge that is attached to the strain section of the strain body and whose output value changes according to the deformation (expansion / contraction) of the strain section. And supply detection circuits 80 and 81 for supplying a current to the load cell (especially a strain gauge) and detecting its output value. In the present embodiment, this load cell is configured as follows as an example. Note that the first weight detection unit 38 as the first weight detection unit has a lower power than the power (power consumption) necessary for causing the second weight detection unit 39 to function as the second weight detection unit. In other words, it may be of low output, and its configuration is not particularly limited.

  As shown in FIG. 1, FIG. 2 or FIG. 3, in the present embodiment, the same load cell 60 is provided at each of the four corners of the weight scale 1. Each load cell 60 (60a, 60b, 60c, 60d) has a strain generating body 47, a first strain gauge 48, and a second strain gauge 49. The strain body 47 includes a load element 47a, an attachment element 47b, and a strain generation portion 47c that couples the load element 47a and the attachment element 47b. A first strain gauge 48 is affixed to one surface of the strain generating portion 47c (the surface facing the cover member 20a in FIG. 1, see FIG. 3), and the other surface (the surface facing the bottom plate member 20b in FIG. 1). A second strain gauge 49 is affixed. The first strain gauge 48 may be attached to the surface facing the bottom plate member 20b, and the second strain gauge 49 may be attached to the surface facing the cover member 20a. Further, as shown in FIGS. 2A and 4, the first strain gauge 48 includes, for example, four resistance members R1 (R1a, R1b, R1c, R1d), R2 (R2a, R2b, R2c, R2d). , R3 (R3a, R3b, R3c, R3d) and R4 (R4a, R4b, R4c, R4d) are configured to form a Wheatstone bridge circuit (hereinafter referred to as a bridge circuit). 2B and 4, the second strain gauge 49 includes, for example, four resistance members R5 (R5a, R5b, R5c, R5d), R6 (R6a, R6b, R6c, R6d). , R7 (R7a, R7b, R7c, R7d), R8 (R8a, R8b, R8c, R8d) are configured to form a bridge circuit.

  Furthermore, a supply detection circuit for supplying a current to the bridge circuit and detecting an output voltage (output value) is connected to each bridge circuit. A supply detection circuit 80 (80a, 80b, 80c, 80d) is connected to the bridge circuit configured by the first strain gauge 48, and a supply detection circuit is connected to the bridge circuit configured by the second strain gauge 49. 81 (81a, 81b, 81c, 81d) is connected.

  In the present embodiment, multiplexers 82 and 83 are interposed between the supply detection circuits 80 and 81 and the control circuit 31. By interposing the multiplexer 82 (83), the output signals from the supply detection circuits 80a to 80d (81a to 81d) are sequentially input to the multiplexer 82 (83) and output to the control circuit 35, or the control circuit The control signal output from 35 can be sequentially output to the supply detection circuits 80a to 80d (81a to 81d).

  As described above, in the present embodiment, the first weight detection unit 38 according to the present invention includes the strain generating body 47, the first strain gauge 48 attached to the upper surface of the strain generating unit 47c, and the supply detection circuit 80. The second weight detection unit 39 according to the present invention is configured by the strain generating body 47, the second strain gauge 49 attached to the lower surface of the strain generating portion 47c, and the supply detection circuit 81. That is, the strain generating body 47 of the load cell 60 of the first weight detection unit 38 is configured to use the same strain generating body as the load cell 60 of the second weight detection unit 39.

The load cell 60 as described above is attached inside the scale 1 as follows. The frame member 40 is formed of a material having high strength such as metal (aluminum, for example), and load cells 60 (60a, 60b, 60c, 60d) are placed at four corners of the upper surface (the surface on the cover member 20a side). A mounting recess 41 that can be accommodated and mounted one by one is formed. Further, a circular hole portion 42 through which the leg portion 65 can be inserted is provided in each mounting recess 41. On the other hand, the bottom plate member 20b is provided with holes 20b ₁ , 20b ₂ , 20b ₃ and 20b ₄ through which the legs 65 can be inserted at positions corresponding to the circular holes 42. The load element 47 a of the strain body 47 of each load cell 60 (60 a, 60 b, 60 c, 60 d) is attached with a leg 65 by a screw 67 with a spacer 69 interposed, and the attachment element 47 b has an spacer 69 interposed. It is attached by screws 67 to the inside of each attachment recess 41. FIG. 1 shows a state before the load cell 60a is attached and a state after the load cells 60b, 60c, and 60d are attached. When the frame member 40 in which each load cell 60 is attached to each attachment recess 41 in this manner is disposed between the cover member 20a and the bottom plate member 20b, the holes 20b ₁ , 20b ₂ , 20b ₃ , Since the leg portion 65 attached to each load cell 60 protrudes from 20b ₄ , the weight scale 1 is grounded at the leg portion 65.

  As a result, when the person to be measured is placed on the placement portion 1a of the scale 1, the strain body 47 of the load cell 60 is deformed (stretched) in a substantially S shape in side view at the strain portion 47c. Accordingly, the first strain gauge 48 and the second strain gauge 49 also expand and contract. Since the output value of the load cell 60 changes according to the expansion and contraction of the first strain gauge 48 and the second strain gauge 49, the control circuit 31 outputs the load cell 60 when no load is applied to the mounting portion 1a. The weight is obtained from the difference between the value (so-called zero point) and the output value when a load is applied, and the weight of the subject is measured.

  The resistance members R1 (R1a, R1b, R1c, R1d), R2 (R2a, R2b, R2c, R2d), R3 (R3a, R3b, R3c, R3d), R4 (R4a, R4b, R4c, R4d), and resistance members R5 (R5a, R5b, R5c, R5d), R6 (R6a, R6b, R6c, R6d), R7 (R7a, R7b) constituting the second strain gauge 49 , R7c, R7d), and R8 (R8a, R8b, R8c, R8d) are such that the power consumed by the first weight detector 38 is lower than the power consumed by the second weight detector 39. Is set to

  The first weight detection unit 38 is configured to determine whether or not the measurement subject is placed on the placement unit 1a, and is required to accurately measure the weight of the measurement subject. It is not necessary that the weight detector 39 is as accurate as the weight detector 39, and a relatively inexpensive one can be adopted. Further, since the second weight detection unit 39 detects the body weight of the measurement subject placed on the placement unit 1a, higher measurement accuracy is required than the first weight detection unit 38.

  Further, like the weight scale 1 of the present embodiment, a so-called step-on type weight scale detects that the person to be measured is placed on the placement portion 1 a of the weight scale 1 and measures the weight by the weight scale 1. It is designed to start automatically. As described above, when the step-on type weight scale is configured, the weight scale 1 can always be measured more accurately regardless of when and when the measurement subject is placed on the weight scale 1. It is necessary to set and update the latest zero point of the load cell 60 of the second weight detection unit 39 in advance while is not being used (standby state). Therefore, when the weight scale 1 is in the standby state, the output value from the second weight detection unit 39 is detected, and the output value is sent to the control circuit 31, which controls the second weight detection unit 39. The zero point is updated by replacing the zero point with a newly measured output value.

  Next, a basic control flow when measuring the weight of the person to be measured with the weight scale 1 having the above configuration will be described with reference to FIG. In the flow in FIG. 5, it is assumed that the zero point update in the first weight detection unit 38 and the second weight detection unit 39 is performed in advance.

  First, a control signal is sent from the control circuit 31 of the scale 1 to the switching circuit 35, and the switching circuit 35 is set to the first weight detection unit 38 (step S101). Next, the output value of the first strain gauge 48 is acquired from the first weight detection unit 38 every time a predetermined time interval preset and stored in the storage unit 33 elapses (step S102). Further, the control circuit 31 compares the output value obtained from the first weight detection unit 38 with a predetermined threshold value to determine whether or not the measurement subject is placed on the placement unit 1a ( Step S103).

  If the output value obtained from the first weight detection unit 38 does not exceed the threshold value, it is determined that the measurement subject is not placed on the placement unit 1a (NO in step S103). In this case, after the elapse of a predetermined time interval, the output value from the first weight detection unit 38 is acquired, and these steps are repeated until the output value exceeds a predetermined threshold value.

  When the output value exceeds the threshold value, it is determined that the person to be measured is placed on the placement unit 1a (YES in step S103), and the switching circuit 35 is set to the second weight detection unit 39 ( The process proceeds to step S104), and the function of the first weight detector 38 is stopped.

  In step S104, the switching circuit 35 is set from the first weight detection unit 38 to the second weight detection unit 39 by the control signal from the control circuit 31, and the second weight detection unit 39 functions (measurement state). ) In step S105, the control circuit 31 acquires an output value indicating the load from the second weight detection unit 39, and calculates a difference between this output value and the output value as the zero point of the second weight detection unit 39. Based on the weight of the person to be measured.

  In the weight scale 1 of the above-described embodiment, in the standby state where the person to be measured is not placed on the placement unit 1a, that is, the weight scale 1 is not used for weight measurement, the first weight detection unit 38 is provided. It is made to function, and monitoring whether a to-be-measured person is mounted in the mounting part 1a is performed reliably, suppressing power consumption low. When it is determined that the person to be measured is placed on the placement unit 1a, the second weight detection unit 39 is caused to function as a measurement state, and accurate measurement of the body weight of the person to be measured is started. Therefore, the weight can be secured with high accuracy while suppressing the power consumption of the scale 1 as a whole. A specific example of weight measurement will be described in Example 1 described later.

  Hereinafter, a control flow of the weight scale according to the first embodiment will be described with reference to FIG. The configuration of the weight scale according to Example 1 is the same as that of the above embodiment, and the difference is the control flow. Accordingly, reference is made to FIGS. 1 to 4 as necessary.

  The control flow of the weight scale of Example 1 is the same up to step S102 in which the output value of the first strain gauge 48 is acquired from the first weight detection unit 38 in the control flow of the weight scale 1 according to the embodiment. Next, the control circuit 31 compares the output value obtained from the first weight detection unit 38 with a predetermined threshold value, and determines whether or not the measurement subject is placed on the placement unit 1a (step). S103). If the output value exceeds a predetermined threshold value, it is determined that the person to be measured is placed on the placement unit 1a (YES in step S103), and the switching circuit 35 is set to the second weight detection unit 38. The process proceeds to (Step S104).

  On the contrary, if the output value does not exceed the predetermined threshold value, it is determined that the person to be measured is not placed on the placement unit 1a (NO in step S103), and the zero point of the second weight detection unit 39 is updated. The control circuit 31 determines whether or not a predetermined time interval has elapsed (step S201). If the predetermined time interval has not elapsed (NO in step S201), the process returns to step S102, and the output value from the first weight detection unit 38 is acquired again after the predetermined time interval has elapsed. The time interval for returning to step S102 and reacquiring the output value from the weight detection unit 38 is set in advance.

  In step S201, if a predetermined time interval for updating the zero point has elapsed, if it is determined by the control circuit 31 (YES in step S201), the control circuit 31 sends a control signal to the switching circuit 35, The switching circuit 35 sets the first weight detector 38 to the second weight detector 39 (step S202).

  Further, the control circuit 31 acquires an output value from the second weight detection unit 39 (step S203). The output value acquired at this time is an output value in a state where no load is applied to the placement unit 1a. The output value acquired in step S203 is compared with the output value of the zero point already stored in the storage unit 33 (the latest updated zero point), and it is determined whether the zero point needs to be updated. (Step S204). If the difference between the output value obtained in step S203 and the output value of the zero point already stored in the storage unit 33 does not exceed the predetermined threshold value stored in advance in the storage unit 33, zero is output. It is determined that it is not necessary to perform the point update (NO in step S204), the zero point update is not performed, the process returns to step S101, the control circuit 31 sends a control signal to the switching circuit 35, and the switching circuit 35 The weight detection unit 39 to the first weight detection unit 38 are set.

  Conversely, the difference between the output value from the second weight detection unit 39 acquired in step S203 and the output value of the zero point already stored in the storage unit 33 (the latest updated zero point) is If the predetermined threshold value is exceeded, it is determined that the zero point needs to be updated (YES in step S204), and the process proceeds to the step of updating the zero point (step S205). In the step of updating the zero point (step S205), the latest updated zero point already stored in the storage unit 33 is stored as the latest zero point in the output value newly acquired in step S203. Return to. After returning to step S <b> 101, the control circuit 31 sends a control signal to the switching circuit 35, and the switching circuit 35 sets the second weight detection unit 39 to the first weight detection unit 38.

  If it is determined in step S103 that the person to be measured is placed on the placement unit 1a (YES in step S103), the switching circuit 35 is set to the second weight detection unit 39 (step S104). )

  In step S104, the control circuit 31 sends a control signal to the switching circuit 35, and the switching circuit 35 sets the first weight detection unit 38 to the second weight detection unit 39, so that the second weight detection unit 39 functions. It becomes a state (measurement state). Then, the control circuit 31 acquires an output value indicating the load from the second weight detection unit 39 (step S105), and calculates the difference between the output value and the output value that is the zero point of the second weight detection unit 39. Based on the weight of the person to be measured, the weight is measured (step S106).

  Next, the control circuit 31 displays the weight of the person measured in step S106 on the display unit 21, and notifies the person to be measured of the measured weight (step S107). After the weight is displayed on the display unit 21 and after a predetermined time has elapsed, the output value from the second weight detection unit 39 is acquired again (step S108). If the difference between the output value and the output value that is the zero point does not exceed a predetermined threshold value, the control circuit 31 determines that the person to be measured has descended from the placement unit 1a (YES in step S109). ), The display of the display unit 21 is turned off by the control circuit 31 (step S110). Thereafter, the process returns to step S101 again, the switching circuit 35 is set to the first weight detection unit 38, the weight scale 1 enters a standby state, and the control flow described above is repeated.

  On the other hand, if the difference between the output value and the output value that is the zero point exceeds a predetermined threshold value in step S109, it is determined that the person to be measured is still on the mounting portion 1a ( NO in step S109), the weight display on the display unit 21 is maintained. Then, after a predetermined time interval that has been set in advance, the output value from the second weight detection unit 39 is acquired again (step S108), and it is determined in the control circuit 31 whether or not the measurement subject is placed, It repeats until it determines with a to-be-measured person getting out of the mounting part 1a.

  In the first embodiment, the control flow for returning to step S108 is described when it is determined in step S109 that the person to be measured has not descended from the placement unit 1a (NO in step S109). It is good also as a control flow which returns to step S105 so that a body weight may be measured and displayed again using the output value acquired from the detection part 39 (it shows with the broken line of FIG. 6). Furthermore, after the weight is displayed on the display unit 21 (step S107), the control unit may turn off the display unit 21 after a predetermined time without performing the above-described repeated processing (step S110) and return to step S101.

  As described above, in the weight scale 1, the first weight detection unit 38 that mainly consumes relatively little power is caused to function in a standby state where the measurement subject is not placed on the placement unit 1 a. And it is the structure which shifts to the measurement state set to the 2nd weight detection part 39 which measures the to-be-measured person's body weight only after it discriminate | determines that the to-be-measured person is mounted in the mounting part 1a. Therefore, the power consumption can be relatively reduced in the standby state, and in the measurement state, the second weight detection unit 39 that can secure the required measurement accuracy is caused to function, so that the power consumption can be suppressed as a whole.

  Specific examples of the second strain gauge 49 of the second weight detection unit 39 and the first strain gauge 48 of the first weight detection unit 38 in the first embodiment will be described. As an example, when the resistance members (R5, R6, R7, R8) constituting the second strain gauge 49 are 1 kΩ, the resistance members (R1, R2, R3, R4) constituting the first strain gauge 48 are used. ) Is preferably 3 kΩ or more. According to this, the first weight detection unit 38 can obtain measurement accuracy sufficient to determine that the measurement subject is placed on the placement unit 1a, and in comparison with the second weight detection unit, The power consumption of the first weight detection unit can be kept low.

  Next, a weight scale including a first weight detection unit and a second weight detection unit that adopt a bridge circuit different from the embodiment and the first example will be described as a second example. FIG. 7 is a block diagram illustrating a control system of the weight scale according to the second embodiment.

  As shown in FIG. 7, the control circuit 431 is electrically connected to the display unit 421, the operation unit 422, the storage unit 433, the switching circuit 435, and the time measuring unit 436, as in the above embodiment and example 1. Control each function. Furthermore, the control circuit 431 is selectively connected to the first weight detection unit 438 and the second weight detection unit 439 via the switching circuit 435, and the first weight detection unit 438 or the second weight detection unit 438 is connected. The output value from the detection unit 439 is selectively received, and the weight can be calculated according to a predetermined program. Since the function of each component is the same as that of the above-described embodiment, the details are omitted.

  In order to selectively connect the first weight detector 438 or the second weight detector 439 to the control circuit 431, the switching circuit 435 includes a control circuit 431, a first weight detector 438, and a second weight detector 438. 2 weight detection unit 439. Therefore, when the switching circuit 435 receives a control signal from the control circuit 431, the switching circuit 435 connects to one of the first weight detection unit 438 or the second weight detection unit 439 in response to the control signal. Set to.

  Also in the present embodiment, the same load cell is provided at each of the four corners of the weight scale as in the embodiment shown in FIG. 2 and the first embodiment, and four resistances are provided in the strain generating portion of the strain generating body of each load cell. A first strain gauge 448 and a second strain gauge 449 made of members are respectively attached. The difference between the first embodiment and the first embodiment is that the resistance members R1a to R1d, R2a to R2d, R3a to R3d, and R4a to R4d of the first strain gauge 448 form a bridge circuit as a whole. The resistance members R5a to R5d, R6a to R6d, R7a to R7d, and R8a to R8d of the second strain gauge 449 are configured to form one bridge circuit as a whole, and no multiplexer is required. Is a point. Therefore, the second weight detection unit 439 and the first weight detection unit 438 are each configured to include a single bridge circuit.

  Furthermore, supply detection circuits 480 and 481 for supplying a current to the bridge circuit and detecting an output voltage (output value) are connected to each bridge circuit. A supply detection circuit 480 is connected to the bridge circuit configured by the first strain gauge 448, and a supply detection circuit 481 is connected to the bridge circuit configured by the second strain gauge 449. Further, the resistance members of the second strain gauge 449 and the first strain gauge 448 are set such that the power consumed by the first weight detector 438 is lower than the power consumed by the second weight detector 439. Set the resistance value.

  According to the weight scale including the first weight detection unit 438 and the second weight detection unit 439 configured as described above, there is an advantage that the control and the structure can be simplified as compared with the first embodiment. Since other operations and effects are the same as those of the first embodiment, details are omitted.

  Next, a weight scale including a first weight detection unit 538 and a second weight detection unit 539 adopting a bridge circuit different from the embodiment and Examples 1 and 2 will be described as Example 3. FIG. 8 is a diagram in which a block diagram showing a control system of a weight scale according to the third embodiment is associated with a plan view and a back surface of the load cell 560.

  As shown in FIG. 8, the control circuit 531 is electrically connected to the display unit 521, the operation unit 522, the storage unit 533, the switching circuit 535, and the time measuring unit 536, as in the embodiment and Examples 1 and 2. Control each function. Further, the control circuit 531 is selectively connected to the first weight detection unit 538 and the second weight detection unit 539 via the switching circuit 535, and the first weight detection unit 538 or the second weight detection unit 538 is detected. The output value from the unit 539 is selectively received, and the weight can be calculated according to a predetermined program. Since the function of each component is the same as that of the above-described embodiment, the details are omitted.

  In order to selectively set the first weight detection unit 538 or the second weight detection unit 539 with respect to the control circuit 531, the switching circuit 535 includes the control circuit 531, the first weight detection unit 538, and the first weight detection unit 538. 2 weight detection unit 539. Therefore, when the switching circuit 538 receives the control signal from the control circuit 531, the switching circuit 535 is connected to one of the first weight detection unit 538 or the second weight detection unit 539 in response to the control signal. Set to.

  Also in this embodiment, the same load cell 560 is provided at each of the four corners of the weight scale as in the embodiment shown in FIG. 2 and Examples 1 and 2, but each load cell 560 (560a, 560b, 560c, 560d). A first strain gauge 548 and a second strain gauge 549 made of two resistance members are respectively attached to the strain generating portions of the strain generating body. That is, the first strain gauge 548 includes resistance members R3 (R3a to R3d) and R4 (R4a to R4d), and the second strain gauge 549 includes resistance members R1 (R1a to R1d) and R2 (R2a to R2d). The first strain gauge 548 is a strain generating portion on the plane side of the load cell 560 (see the lower side in FIG. 8), and the second strain gauge 549 is a strain generating portion on the back side of the load cell 560 (see the upper side in FIG. 8). , Each is affixed.

  The difference from the above embodiment and Example 1 is that the resistance members R1a to R1d and R2a to R2d of the first strain gauge 548 form a bridge circuit as a whole, and the resistance of the second strain gauge 549 is different. The members R3a to R3d and R4a to R4d are configured so as to form one bridge circuit as a whole, and a multiplexer is not required. Therefore, the second weight detection unit 539 and the first weight detection unit 538 are each configured to include a single bridge circuit.

  In addition, supply detection circuits 580 and 581 for supplying current to the bridge circuit and detecting an output voltage (output value) are connected to each bridge circuit. A supply detection circuit 580 is connected to the bridge circuit configured by the first strain gauge 548, and a supply detection circuit 581 is connected to the bridge circuit configured by the second strain gauge 549. The resistance members of the second strain gauge 549 and the first strain gauge 548 are configured such that the power consumed by the first weight detection unit 538 is lower than the power consumed by the second weight detection unit 539. Set the resistance value.

  According to the weight scale including the first weight detection unit 538 and the second weight detection unit 539 configured as described above, there is an advantage that the control and the structure can be simplified as compared with the first embodiment. Since other operations and effects are the same as those of the first embodiment, details are omitted.

  The present invention can be applied not only to measuring the weight of a person (a person to be measured), but also to a weight measuring device for measuring the weight of an object (an object to be measured). Thus, hereinafter, a weight measuring apparatus capable of measuring the weight of an object to be measured will be described as a fourth embodiment of the weight measuring apparatus of the present invention. 9A is a partial cross-sectional view showing the internal configuration of the weight measuring device 301, and FIG. 9B shows the load cell 360 of the weight measuring device 301 along the line IX-IX in FIG. 9A. FIG. 10 is a block diagram illustrating a control system of the weight measuring apparatus 301 according to the fourth embodiment.

  Unlike the configuration in which the load cells are provided in four places as in the above-described embodiment and example 1, the weight measuring device 301 has a configuration using one load cell 360, and the load cell 360 is a first weight detection unit. 338 and the second weight detector 339.

  As shown in FIG. 10, the control circuit 331 is electrically connected to a display unit 391, an operation unit 392, a storage unit 333, a switching circuit 335, and a time measuring unit 336, and controls each function. Further, the control circuit 331 is selectively connected to the first weight detection unit 338 and the second weight detection unit 339 via the switching circuit 335, and the first weight detection unit 338 or the second weight detection unit 339 is detected. The output value from the unit 339 is selectively received, and the weight can be calculated according to a predetermined program. In addition, the control unit 331 performs display control of the display unit 391, data read / write processing with respect to the storage unit 333, and the like. In the present embodiment, the first weight detection unit 338 and the second weight detection unit 339 include supply detection circuits 380 and 381, respectively. The operation unit 392 is data input means (input means) for performing initial setting of the weight measuring device 301 and the like. Note that the details of the configuration and function of each element are the same as those in the above-described embodiment, and thus description thereof is omitted.

  In order to selectively set the first weight detector 338 or the second weight detector 339 with respect to the control circuit 331, the switching circuit 335 includes the control circuit 331, the first weight detector 338, and the second weight detector 338. 2 weight detection unit 339. Therefore, when the switching circuit 538 receives a control signal from the control circuit 331, the switching circuit 335 is connected to one of the first weight detection unit 338 or the second weight detection unit 339 in response to the control signal. Set to.

  The load cell 360 according to the fourth embodiment includes a strain generating body 347 made of a substantially rectangular parallelepiped metal member, a first strain gauge 348, and a second strain gauge 349. As shown in FIG. 9, the strain generating body 347 connects the fixed end 325, the movable end 326, the fixed end 325 and the movable end 326, and a connecting portion 321 including the strain generating portions 319a and 319b. Have. The strain generating portions 319a and 319b of the load cell 360 in the fourth embodiment are portions between the fixed end portion 325 and the movable end portion 326, and are arranged on the lower surface of the strain generating body 347 in the short direction of the strain generating body 347. This is a portion having two grooves 322 and 323 provided in parallel on the lower surface. Gauges 348 a and 348 b are attached to the strain generating portions 319 a and 319 b at positions corresponding to the grooves 322 and 323. Each of the gauge 348a and the gauge 348b includes two resistance members R1 and R4, and R2 and R3, and the gauge 348a and the gauge 348b constitute a set to constitute the first strain gauge 348. Further, a gauge 349 a and a gauge 349 b are attached to the first strain gauge 348 in a position corresponding to the groove 322 and the groove 323. Each of the gauge 349a and the gauge 349b includes two resistance members R5 and R8, and R6 and R7, and the gauge 349a and the gauge 349b constitute a pair to constitute a second strain gauge 349. That is, the first strain gauge 348 and the second strain gauge 349 of the load cell 360 in the fourth embodiment are configured to be juxtaposed on the same surface of the same strain generating body 347. As shown in FIG. 10, the resistance members R1, R2, R3, and R4 of the first strain gauge 348 and the resistance members R5, R6, R7, and R8 of the second strain gauge 349 constitute a bridge circuit. ing. Further, the resistance values of the resistance members R1 to R4 are set to be lower than the resistance values of the resistance members R5 to R8. Furthermore, a supply detection circuit for supplying a current to the bridge circuit and detecting an output voltage (output value) is connected to each bridge circuit. A supply detection circuit 380 is connected to the bridge circuit configured by the first strain gauge 348, and a supply detection circuit 381 is connected to the bridge circuit configured by the second strain gauge 349.

  In the present embodiment, the strain body 347, the first strain gauge 348, and the supply detection circuit 380 constitute the first weight detector 338 in the present invention, and the strain body 347, The second strain gauge 349 and the supply detection circuit 381 constitute a second weight detection unit 339 according to the present invention.

  The load cell 360 as described above is attached to the weight measuring device 301 as follows. The fixed end 325 of the strain generating body 347 is fixed to the base 359 through a connecting member 365 by a fixing member (not shown). The base 359 is fixed to the bottom plate of the weight measuring device 301. In addition, a support frame 350 extending in the left-right direction in FIG. 9A is fixed to the movable end portion 326 via a connecting member 345 by a fixing member (not shown). Further, a columnar support portion 351 that protrudes from the inside of the weight measuring device 301 to the outside is fixed at substantially the center in the longitudinal direction of the support frame 350, and the columnar support portion 351 is attached to the mounting portion 301a.

  As a result, when the object to be measured is placed on the placement portion 301a of the weight measuring device 301, the strain body 347 of the load cell 360 is deformed (stretched) in a substantially S shape in side view at the strain portions 319a and 319b. According to the deformation, the first strain gauge 348 and the second strain gauge 349 expand and contract. The output value of the load cell 360 changes according to the expansion and contraction of the first strain gauge 348 and the second strain gauge 349.

  In this manner, a change in the output value of the first strain gauge 348 of the first weight detection unit 338 is detected, and it is determined whether or not the object to be measured is placed on the placement unit 301a. Further, when the control circuit 331 determines that an object to be measured is placed on the basis of the output value from the first weight detection unit 338, the output value from the second strain gauge 349 of the second weight detection unit 339 is set. Based on this, the weight of the object to be measured is measured. The measured weight is displayed on the display unit 391. Details of the control flow of the weight measuring apparatus 301 are the same as those in FIGS. 5 and 6, and thus detailed description thereof is omitted.

  The weight measurement device 301 causes the first weight detection unit 338 that consumes relatively little power to function in a standby state in which the object to be measured is not placed on the placement unit 301a. Only when it is determined that the object to be measured is placed on the placement unit 301a, the second weight detection unit 339 that measures the weight of the object to be measured is set and the measurement state is entered. Therefore, when the weight measuring device 301 is in the standby state, the power consumption can be relatively reduced and the power consumption during standby can be suppressed.

  Next, a weight measuring device using a strain gauge having another configuration will be described as a fifth embodiment. FIG. 11A is a partial sectional view showing a load cell 660 corresponding to FIG. 9B, and FIG. 11B is a block diagram showing a control system of the weight measuring apparatus according to the fifth embodiment. The configuration of the fifth embodiment is the same as that of the fourth embodiment except for the configuration of the strain gauge, and therefore, FIG. 9 is referred to if necessary.

  The load cell 660 according to the fifth embodiment includes a strain generating body 347, a first strain gauge 648, and a second strain gauge 649. As shown in FIG. 11A, the strain generating body 347 is provided with strain generating portions 319a and 319b by forming grooves 322 and 323, and gauges corresponding to the strain generating portions 319a and 319b. 648a and gauge 649a, and gauge 648b and gauge 649b are attached, respectively.

  The gauge 649a has a resistance member R1 and the gauge 649b has a resistance member R2, and the gauge 649a and the gauge 649b constitute a pair to constitute a second strain gauge 649. Similarly, the gauge 648a has a resistance member R3 and the gauge 648b has a resistance member R4, and the gauge 648a and the gauge 648b constitute a first strain gauge 648. As described above, the first strain gauge 648 and the second strain gauge 649 of the load cell 660 according to the fifth embodiment are arranged side by side on the same surface of the same strain generating body 347. Further, the resistance values of the resistance members R1 and R2 are set to be lower than the resistance values of the resistance members R3 and R4.

  Further, a supply detection circuit for supplying current to each circuit and detecting an output voltage (output value) is connected. A supply detection circuit 680 is connected to a circuit constituted by the first strain gauge 648, and a supply detection circuit 681 is connected to a circuit constituted by the second strain gauge 649.

  In the present embodiment, the first weight detector 638 is configured by the strain body 347, the first strain gauge 648, and the supply detection circuit 680, and the strain body 347 and the second strain are provided. The gauge 649 and the supply detection circuit 681 constitute a second weight detection unit 639.

  With the above configuration, when the object to be measured is placed on the placement portion 301a of the weight measuring device 301, the strain body 347 of the load cell 660 is deformed (stretched) in a substantially S shape in side view at the strain portions 319a and 319b. In response to the deformation, the first strain gauge 648 and the second strain gauge 649 also expand and contract. The output value of the load cell 360 changes according to the expansion and contraction of the first strain gauge 648 and the second strain gauge 649.

  In this manner, a change in the output value of the first strain gauge 648 of the first weight detection unit 638 is detected, and it is determined whether or not the object to be measured is placed on the placement unit 301a. Furthermore, if the control circuit 631 determines that an object to be measured is placed based on the output value from the first weight detection unit 338, the output value from the second strain gauge 649 of the second weight detection unit 639 is set. Based on this, the weight of the object to be measured is measured. According to the weight measuring device of the fifth embodiment, the configuration of the load cell can be further simplified as compared with the weight measuring device 301 of the fourth embodiment. Since the functions and effects of the fifth embodiment are the same as those of the fourth embodiment, detailed description thereof is omitted.

  In Examples 4 and 5, a configuration in which the grooves 322 and 323 are provided in the rectangular parallelepiped strain generating body 347 is used. Instead of forming the grooves, a through hole penetrating in the short direction of the strain generating portion is used. It is good also as a structure to form, Furthermore, it is also possible to use the rectangular parallelepiped strain generating body which does not form a groove | channel and a through-hole. In the present invention, the first strain gauge and the second strain gauge to be attached to the strain body of the load cell may be provided on the same surface as in Examples 4 and 5, You may provide in a different surface like Example 1 thru | or 3. On the other hand, the first strain gauge in the embodiment and Examples 1 to 3 has a configuration in which the upper surface of the strain-generating body 47 and the second strain gauge are each pasted on the lower surface of the strain-generating body 47 one by one. Is not limited to this configuration, and the first strain gauge and the second strain gauge may be attached to the same surface of the strain generating body 47.

  In the embodiment and Example 1 described above, the description has been given of the case where four resistance members are provided for each strain gauge, and a bridge circuit is configured for each strain gauge. In the second embodiment, the bridge circuit is configured by using a plurality of strain gauge resistance members. Further, in the third embodiment, the description has been given of the case where two resistance members are provided for each strain gauge, and a bridge circuit is configured by using a plurality of strain gauge resistance members. In the fourth embodiment, two resistance members are provided for each strain gauge, and a bridge circuit is configured using the resistance members of two strain gauges. Further, in the fifth embodiment, one resistance member is provided for each strain gauge, and a so-called half-bulge circuit is configured by using two strain gauge resistance members. However, the present invention is not limited to these configurations, as long as the combination is such that the power consumption when the first weight detection unit functions is less than the power consumption when the second weight detection unit functions. Can be adopted.

  Furthermore, in the said embodiment and Example 1, although it was set as the structure which provided the 1st weight detection part 38 in four places of each corner part of the weight scale 1, the arrangement | positioning location of a 1st weight detection part was measured. The number may be reduced as long as the measurement accuracy to the extent that it is determined whether or not the target is placed on the placement unit is obtained. In addition, as described above, when the first weight detection unit and the second weight detection unit are configured by one load cell having a common strain generating body, it is preferable in that the number of parts can be reduced. The present invention is not limited to this, and each of the first weight detection unit and the second weight detection unit can be configured by a separate and independent load cell.

  Further, in the embodiment and Examples 1 to 3, the weight scale for measuring the body weight of the measurement subject has been described. However, the weight measuring device of the present invention is not limited to the weight scale. The present invention can be widely applied to biological measuring devices such as a meter. In addition, the weight measuring devices described in the fourth and fifth embodiments are more specifically the weight measuring device for cooking, the weight measuring device for experiment, the weight measuring device for baggage for delivery work, etc. Needless to say, the present invention can be applied to apparatuses for various purposes for measuring weight.

  The present invention can be embodied in many forms without departing from its essential characteristics. Therefore, it is needless to say that the above-described embodiments and examples are merely illustrative and do not limit the present invention.

It is a perspective view of a weight scale concerning an embodiment. (A) The elements on larger scale of the II section of FIG. 1 of the load cell of the weight scale which concern on embodiment are shown, (b) is a figure which shows the back surface of the load cell of FIG. 2 (a). It is a side view which shows a part of load cell seen from the arrow III direction of Fig.2 (a). It is the figure which matched the block diagram which shows the control system of the weight scale which concerns on embodiment, and the top view and back view of a load cell. It is a figure which shows an example of the control flow of the weight scale which concerns on embodiment. It is a figure which shows the control flow of the weight scale which concerns on Example 1. FIG. 6 is a block diagram showing a control system of a weight scale according to Embodiment 2. FIG. It is the figure which matched the block diagram which shows the control system of the weight scale which concerns on Example 3, and the top view and back surface of a load cell. (A) is a fragmentary sectional view which shows the internal structure of the weight measuring apparatus based on Example 4, (b) is a fragmentary sectional view which shows the load cell of the weight measuring apparatus along the IX-IX line of Fig.9 (a). is there. FIG. 10 is a block diagram illustrating a control system of a weight measuring apparatus according to a fourth embodiment. FIG. 10A is a partial cross-sectional view showing a load cell corresponding to FIG. 9B, and FIG. 10B is a block diagram showing a control system of the weight measuring apparatus according to the fifth embodiment.

Explanation of symbols

1 Weight scale (weight measuring device)
1a mounting portion 20a covering member 20b bottom plate member _{20b 1, 20b 2, 20b 3} , 20b 4 holes 21,421,521 display 22,422,522 operation unit 31,431,531 control circuit (control means)
33, 433, 533 Storage unit 34, 434, 534 Power supply unit 35, 435, 535 Switching circuit (switching means)
36, 436, 536 Timekeeping section 38, 438, 538 First weight detection section (first weight detection means)
39, 439, 539 Second weight detection unit (second weight detection means)
40 frame member 41 mounting recess 42 circular hole 47 strain generating body 47a load element 47b mounting element 47c strain generating portion 48, 448, 548 first strain gauge 49, 449, 549 second strain gauge 60 (ad) 560 (a to d) Load cell 65 Leg 67 Screw 69 Spacer 80, 81, 480, 481, 580, 581 Supply detection circuit 82, 83 Multiplexer 301 Weight measuring device 301a Mounting part 319a, 319b Straining part 321 Connecting part 322, 323 Groove 325 Fixed end 326 Movable end 338, 638 First weight detector (first weight detector)
339, 639 Second weight detection unit (second weight detection means)
345 connecting member 347 strain generating body 348, 648 first strain gauge 348a, 648a gauge 348b, 648b gauge 349, 649 second strain gauge 349a, 649a gauge 349b, 649b gauge 359 base 360, 660 load cell 365 connecting member R1 (Ad) to R8 (ad) Resistance member

Claims (5)

A weight measuring device that automatically starts measuring a weight when a measurement target is placed on a placement unit,
First weight detecting means for detecting whether or not a measurement target is placed on the mounting portion;
Second weight detection means for detecting the weight of the measurement object;
If it is determined based on the output value from the first weight detection means that the measurement target is placed on the placement section, the weight of the measurement target is acquired based on the output value from the second weight detection means. Control means for
The first weight detection means is a load cell in which a first strain gauge is attached to a strain body,
The second weight detection means is a load cell in which a second strain gauge is attached to a strain body,
The resistance value of the first strain gauge is higher than the resistance value of the second strain gauge,
The weight measuring apparatus characterized in that the power consumed by the first weight detecting means is lower than the power consumed by the second weight detecting means. The weight measuring apparatus according to claim 1 , wherein the first strain gauge and the second strain gauge are attached to the same strain generating body.   The strain body is formed in a bilaterally symmetric shape, and has a strain section disposed in the center of the strain body and extending in parallel with the symmetry axis,
  The first strain gauge is attached to one of upper and lower surfaces of the strain generating portion,
  The weight measuring apparatus according to claim 2, wherein the second strain gauge is attached to a surface opposite to the top and bottom of the strain-generating portion.   Switching means for switching between the first weight detection means and the second weight detection means; and the control means includes the first weight detection means and the second weight detection means by the switching means. The weight measuring device according to claim 1, wherein the weight measuring device is selectively functioned.   If the control means determines that the object to be measured is not placed on the placement section based on the output value from the first weight detection means, whether or not a predetermined time interval for performing zero point update has elapsed. The weight according to any one of claims 1 to 4, wherein when the predetermined time interval has elapsed, the zero point of the second weight detection means is updated. measuring device.

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