Patent Description:
Weighing apparatus are known which convey an article and measure the weight of the article as it is being conveyed. In such weighing apparatus, for example, noise produced by shock when the article is handed over to a conveyance unit can be included in the weigh signal of a detection unit. To reduce the adverse effect that the noise has on the weighing, weighing apparatus sometimes use a filter to reduce the noise included in the weigh signal.

The frequency of the noise included in the weigh signal may vary depending on the properties of the article that is weighed and the conveyance conditions of the article. For that reason, if the weighing apparatus always uses a filter having the same characteristics, this runs the risk of not being able to sufficiently reduce the noise included in the weigh signal, resulting in a drop in the weighing accuracy of the weighing apparatus. To address this problem, for example patent document <NUM> (<CIT>) discloses a technology that enables the filter characteristics to be changed.

<CIT> discloses a weighing device having a weighing unit for weighing an article and for outputting an original signal, a filter unit for performing a filtering process, a control unit for making a waveform of a weighing signal and a storage unit for storing the original signal and the weighing signal.

<CIT> discloses a weighing device having a speed setting unit for setting a conveyor speed, a filter setting unit for setting a filter based on the conveyor speed and a conveyor distance, and an acquiring unit for acquiring a weight of an apparatus from the filtered signal.

<CIT> discloses a weighing apparatus having a conveyance unit for conveying an article, a weighing unit for weighing the article, and a processing unit with a plurality of digital filters set in advance and for processing an original signal from the weighing unit.

However, when using the kind of filter disclosed in patent document <NUM> (<CIT>), it becomes necessary to actually conduct a test operation of the weighing apparatus to set the filter to use. Furthermore, when using the kind of filter disclosed in patent document <NUM> (<CIT>), a filter setting with which a high weighing accuracy can be realized is not easy to achieve unless one is a knowledgeable and experienced technician.

It is an object of the present invention to provide a weighing apparatus that weighs an article as it is being conveyed and with which it is possible to achieve an appropriate filter setting even if one is not a knowledgeable and experienced technician.

A weighing apparatus of a first aspect includes a conveyance unit, a detection unit, an acquisition unit, and a control unit. The conveyance unit is configured to receive and convey an article. The detection unit is configured to detect the weight of the conveyance unit or, in a case where the conveyance unit is conveying the article, the weight of the conveyance unit and a weight of the article on the conveyance unit and output a weigh signal. The acquisition unit is configured to acquire i) a prescribed weight of the article conveyed by the conveyance unit, ii) a speed at which the article is conveyed by the conveyance unit and iii) a length of the article in the direction in which it is conveyed by the conveyance unit. The control unit is configured to determine, based on the prescribed weight of the article, the speed at which the article is conveyed by the conveyance unit and the length of the article in the direction in which it is conveyed by the conveyance unit that the acquisition unit has acquired, a filter setting to use to filter the weigh signal detected by the detection unit.

The weighing apparatus of the first aspect determines the filter setting to use to filter the weigh signal based on the prescribed weight of the article, the conveyance speed of the article and the length of the article in the conveyance direction that it has acquired. For that reason, in the weighing apparatus of the first aspect, it is possible to determine an appropriate filter setting with which a high weighing accuracy can be realized even if one is not a knowledgeable and experienced technician.

According to a preferred embodiment of the weighing apparatus mentioned above, the weighing apparatus further includes a storage unit. The storage unit is configured to store information in which the prescribed weight of the article or the conveyance speed of the article, the length of the article, and the filter setting are associated with each other. The control unit is configured to determine the filter setting further based on the information stored in the storage unit.

In the weighing apparatus of this embodiment, the prescribed weight of the article or the conveyance speed of the article, the length of the article, and the appropriate filter setting are associated with each other and stored in the storage unit. Therefore, the appropriate filter setting can be determined even without conducting an actual operation of the weighing apparatus.

According to another preferred embodiment of any one of the weighing apparatuses mentioned above, the acquisition unit is further configured to acquire information relating to a vibrational characteristic of a constituent part of the weighing apparatus. The control unit is configured to determine the filter setting further based also on the information relating to the vibrational characteristic of the constituent part of the weighing apparatus that the acquisition unit has acquired.

In the weighing apparatus of this embodiment, it is possible to determine an appropriate filter setting with which a high weighing accuracy can be realized even if the vibrational characteristic of the weighing apparatus change due, for example, to replacement of a part. Furthermore, in the weighing apparatus of the third aspect, the control unit can be shared among plural weighing apparatus whose configurations have different physical structures.

According to another preferred embodiment of any one of the weighing apparatuses mentioned above, the information relating to the vibrational characteristic of the constituent part of the weighing apparatus includes at least one of information about a length of the conveyance unit in the conveyance direction and information about a length of the conveyance unit in a direction orthogonal to the conveyance direction.

In the weighing apparatus of the fourth aspect, it is possible to determine an appropriate filter setting with which a high weighing accuracy can be realized even in a case where the vibrational characteristics change due to a difference in the length of the conveyance unit.

The weighing apparatus of the present invention determines the filter setting to use to filter the weigh signal based on the prescribed weight of the article or the conveyance speed of the article and the length of the article in the conveyance direction that it has acquired. Therefore, it is possible to determine an appropriate filter setting with which a high weighing accuracy can be realized even if one is not a knowledgeable and experienced technician.

A weighing apparatus <NUM> pertaining to an embodiment of the weighing apparatus of the invention will be described with reference to the drawings. It will be noted that the embodiment of the weighing apparatus <NUM> described below is merely an example and that many changes in form and detail may be made without departing from the spirit and scope of the disclosure as defined in the claims.

The overall configuration of the weighing apparatus <NUM> will be described with reference to <FIG>. <FIG> is a schematic front elevation view of the weighing apparatus <NUM> seen in a front elevation. <FIG> is a block diagram of the weighing apparatus <NUM>. <FIG> is a schematic plan view of main parts of the weighing apparatus <NUM> seen from above.

The weighing apparatus <NUM> is a weighing apparatus that weighs an article P while conveying the article P.

As shown in <FIG>, the weighing apparatus <NUM> mainly has a conveyance device <NUM> and a detection device <NUM>. As shown in <FIG>, the weighing apparatus <NUM> also has a control device <NUM> that controls the operations of the conveyance device <NUM> and the detection device <NUM>.

The conveyance device <NUM> receives and conveys the article P, which is supplied from an upstream process not shown in the drawings (e.g., a process to manufacture the article P). Specifically, the conveyance device <NUM> conveys the article P to a place where its weight is detected by the detection device <NUM>.

The detection device <NUM> detects the weight of the article P conveyed by the conveyance device <NUM> and outputs a weigh signal corresponding to the weight it has detected to the control device <NUM>. The control device <NUM> calculates a weight W of the article P based on the weigh signal that the detection device <NUM> output when it detected the weight of the article P. The control device <NUM> also determines whether or not the weight W of the article P it has calculated is within an allowable weight range. What is meant by the weight W of the article P being within an allowable weight range is the weight of the article P is equal to or greater than an allowable minimum weight and equal to or less than an allowable maximum weight.

It will be noted that downstream of the weighing apparatus <NUM>, for example a sorting device not shown in the drawings is disposed. The sorting device sorts the article P based on the weight W of the article P calculated by the control device <NUM>. For example, in a case where the weight W of the article P is outside the allowable weight range, the sorting device removes the article P from the conveyance line of the article P.

The weighing apparatus <NUM> will be described in greater detail below.

It will be noted that in the following description expressions such as "front", "rear", "upper", "lower", "right", and "left" may be used when describing directions and positional relationships, but these expressions are used for convenience of description and should not be construed as limiting the content of the invention. Expressions such as "front", "rear", "upper", "lower", "right", and "left" follow the directions indicated by the arrows in the drawings unless otherwise specified.

The conveyance device <NUM> conveys the article P along a conveyance direction A (see <FIG> and <FIG>).

The conveyance device <NUM> includes a first conveyor <NUM> and a second conveyor <NUM> as well as a first drive unit 18a and a second drive unit 18b. The first drive unit 18a and the second drive unit 18b are, for example, motors.

In the conveyance device <NUM>, as shown in <FIG> and <FIG>, the first conveyor <NUM> and the second conveyor <NUM> are arranged sequentially from upstream in the conveyance direction A of the article P.

As shown in <FIG>, among the first conveyor <NUM> and the second conveyor <NUM>, the first conveyor <NUM> is disposed upstream in the conveyance direction A. The first conveyor <NUM> functions as an intake conveyor that introduces to the weighing apparatus <NUM> the article P conveyed from the process upstream of the weighing apparatus <NUM>. The first conveyor <NUM> conveys the article P in the conveyance direction A and hands over the article P to the second conveyor <NUM>.

The first conveyor <NUM> includes a first conveyor belt 12a (see <FIG>). The first conveyor belt 12a is entrained about a drive roller 122a and a follower roller 122b, and the first conveyor <NUM> conveys the article P on the first conveyor belt 12a in the conveyance direction A as a result of the first drive unit 18a driving the drive roller 122a.

As shown in <FIG>, among the first conveyor <NUM> and the second conveyor <NUM>, the second conveyor <NUM> is disposed downstream in the conveyance direction A. The second conveyor <NUM> receives the article P conveyed by the first conveyor <NUM> and conveys it. The detection device <NUM> detects the weight of the article P as it is being conveyed by the second conveyor <NUM> and outputs the weigh signal. The second conveyor <NUM> conveys the article P in the conveyance direction A and hands over the article P to a process downstream of the weighing apparatus <NUM> (e.g., the sorting device not shown in the drawings).

The second conveyor <NUM> includes a second conveyor belt 14a (see <FIG>). The second conveyor belt 14a is entrained about rollers 144a and 144b, and the second conveyor <NUM> conveys the article P on the second conveyor belt 14a in the conveyance direction A as a result of the second drive unit 18b driving the roller (drive roller) 144a.

The detection device <NUM> will be described with further reference to <FIG> is a schematic configuration diagram of the second conveyor <NUM> of the conveyance device <NUM> and the detection device <NUM>.

As shown in <FIG> and <FIG>, the detection device <NUM> mainly has a sensor <NUM> and a load cell <NUM> serving as an example of a detection unit (a weight sensor).

The sensor <NUM> detects that the article P conveyed by the first conveyor <NUM> has reached the second conveyor <NUM>. The sensor <NUM> is, for example, a photoelectric sensor. However, the type of the sensor <NUM> is not limited to a photoelectric sensor and may be any type as long as it is a sensor that can detect the arrival of the article P to the second conveyor <NUM>.

The control device <NUM> detects the timing when the entire article P is on the second conveyor belt 14a based on the detection result of the sensor <NUM>, a conveyance speed V of the conveyance device <NUM>, and a length L1 of the article P in the conveyance direction A. The control device <NUM> calculates the weight W of the article P based on the weigh signal output by the load cell <NUM> while the entire article P is on the second conveyor belt 14a.

The load cell <NUM> includes a strain element 28a that becomes deformed in proportion to force acting thereon and a strain gauge (not shown in the drawings) that is adhered to the strain element 28a, converts strain into an electrical signal (this signal is called a weigh signal), and outputs the electrical signal. In short, the load cell <NUM> sends a weigh signal corresponding to the force acting thereon. The load cell <NUM> is housed inside a case <NUM> disposed under the second conveyor <NUM> (see <FIG>).

The weight detection by the load cell <NUM> will be described. In describing the weight detection by the load cell <NUM>, details about the structure of the second conveyor <NUM> of the conveyance device <NUM> will first be described.

The second conveyor <NUM> mainly has, in addition to the second conveyor belt 14a, a frame <NUM> as well as a drive roller 144a and a follower roller 144b (see <FIG>).

The frame <NUM> of the second conveyor <NUM> is supported by brackets <NUM> that extend upward from the case <NUM>. The case <NUM>, as shown in <FIG>, is secured to a frame <NUM> of the weighing apparatus <NUM>.

The drive roller 144a and the follower roller 144b, as shown in <FIG>, are provided on both ends of the frame <NUM>. The drive roller 144a and the follower roller 144b are supported by the frame <NUM> so as to be freely rotatable. The second conveyor belt 14a is entrained about the drive roller 144a and the follower roller 144b. The second drive unit 18b drives the drive roller 144a, whereby the second conveyor belt 14a rotates and the second conveyor <NUM> conveys the article P on the second conveyor belt 14a in the conveyance direction A.

Because of the above structure, when the article P is not on the second conveyor belt 14a, the load cell <NUM> detects the weight of the second conveyor <NUM> (the force that the second conveyor <NUM> exerts on the load cell <NUM>), which serves as a conveyance unit, and outputs the weigh signal. It will be noted that, here, the weight of the second conveyor <NUM> is generally the total weight of the frame <NUM>, the drive roller 144a and the follower roller 144b, and the second conveyor belt 14a. Furthermore, when the second conveyor belt 14a is conveying the article P, the load cell <NUM> detects the weight of the second conveyor <NUM> and the weight of the article P on the second conveyor <NUM> and outputs the weigh signal.

The control device <NUM> controls the operations of each part of the weighing apparatus <NUM>. The control device <NUM> also performs a process to calculate the weight W of the article P based on the weigh signal sent by the detection device <NUM>.

The control device <NUM> of this embodiment mainly includes a CPU, a memory comprising a ROM, a RAM, and/or an auxiliary storage device (e.g., flash memory), and various electronic circuits. The control device <NUM> controls the operations of each part of the weighing apparatus <NUM> and performs various processes as a result of the CPU reading and executing programs stored in the memory.

It will be noted that the configuration of the control device <NUM> described here is merely an example configuration of the control device <NUM>, and the same functions as those of the control device <NUM> of this embodiment may be realized by hardware such as a logic circuit or may be realized by a combination of hardware and software. Furthermore, the control device <NUM> may be realized by one device or may be realized by plural devices.

The control device <NUM> is electrically connected to the first drive unit 18a and the second drive unit 18b of the conveyance device <NUM> and the sensor <NUM> and the load cell <NUM> of the detection device <NUM>.

The control device <NUM> is also electrically connected to an input device <NUM> and an output device <NUM> (see <FIG>). The input device <NUM> receives various types of commands input by an operator of the weighing apparatus <NUM> and various types of information input by the operator. For example, the input device <NUM> is a touch panel display. The commands and information input to the input device <NUM> are sent to the control device <NUM>. The output device <NUM> is controlled by the control device <NUM> and outputs various types of information. For example, the output device <NUM> is a display that displays various types of information. In other words, in this embodiment, a touch panel display functions as the input device <NUM> and the output device <NUM>.

It will be noted that the input device and the output device are not limited to the device exemplified here. For example, the input device may be a mobile device (not shown in the drawings) operated by the operator or the like of the weighing apparatus <NUM> or a device that receives commands and information sent from a central control unit (not shown in the drawings) higher than the weighing apparatus <NUM>. Furthermore, the output device may, for example, be a mobile device (not shown in the drawings) retained by the operator or the like of the weighing apparatus <NUM> or a device that outputs (sends) various types of information to a central control unit (not shown in the drawings) higher than the weighing apparatus <NUM>.

The memory of the control device <NUM> includes a storage unit <NUM> that stores various types of information. Examples of the information stored in the storage unit <NUM> will be described later.

The CPU of the control device <NUM> functions as a control unit <NUM> and an acquisition unit <NUM> by reading and executing programs stored in the memory.

The acquisition unit <NUM> acquires various types of information input to the input device <NUM>. The various types of information acquired by the acquisition unit <NUM> are stored in the storage unit <NUM>.

The information acquired by the acquisition unit <NUM> includes, for example, a prescribed weight Wt of the article P conveyed by the conveyance device <NUM>. The prescribed weight Wt is, in other words, the weight that the article P should normally have (the ideal weight that the article P should have in a case where the article P is an accepted article).

The information acquired by the acquisition unit <NUM> also includes the length L1 of the article P conveyed by the second conveyor <NUM>. Here, the length L1 of the article P conveyed by the second conveyor <NUM> is the length of the article P in the conveyance direction A in a state in which the article P is conveyed by the second conveyor <NUM>.

It will be noted that although here the prescribed weight Wt of the article P and the length L1 of the article P are each input to the input device <NUM>, they are not limited to this.

For example, information about the prescribed weight Wt of the article P and the length L1 of the article P may be stored by type of the article P in the storage unit <NUM>, and the acquisition unit <NUM> may acquire an identifier that identifies the type of the article P input to the input device <NUM>. In this configuration, the acquisition unit <NUM> can acquire the prescribed weight Wt of the article P and the length L1 of the article P by referencing the storage unit <NUM>.

The information acquired by the acquisition unit <NUM> also includes a speed V at which the article P is conveyed by the conveyance device <NUM>. Although this is not intended to limit the acquisition method, here, the conveyance speed V of the article P is input to the input device <NUM>. It will be noted that the acquisition unit <NUM> may acquire, as information about the speed V at which the article P is conveyed by the conveyance device <NUM>, information with which the conveyance speed V of the article P can be identified (e.g., the rotational speed of the motor of the second drive unit 18b).

The control unit <NUM> controls the operations of the weighing apparatus <NUM> based on the commands input to the input device <NUM> and the information acquired by the acquisition unit <NUM>, such as the prescribed weight Wt of the article P, the length L1 of the article P, and the speed V at which the article P is conveyed by the conveyance device <NUM>.

For example, when an operation command is input to the input device <NUM>, the control unit <NUM> controls the operations of the first drive unit 18a and the second drive unit 18b so that the speed at which the article P is conveyed by the first conveyor <NUM> and the second conveyor <NUM> becomes the conveyance speed V acquired by the acquisition unit <NUM>.

Furthermore, for example, the control unit <NUM> calculates the weight W of a given article P based on the weigh signal output by the load cell <NUM> when that article P is being conveyed by the second conveyor <NUM>. Specifically, the control unit <NUM> detects the timing when the entire article P is on the second conveyor belt 14a based on the detection result of the sensor <NUM>, the conveyance speed V of the conveyance device <NUM>, and the length L1 of the article P. The control unit <NUM> calculates the weight W of the article P based on the weigh signal output by the load cell <NUM> while the entire article P is on the second conveyor belt 14a. The calculation of the weight W of the article P by the control unit <NUM> will be described later.

Furthermore, for example, the control unit <NUM> determines whether the weight of the article P it has calculated is within the allowable weight range. For example, the control unit <NUM> determines whether the weight W of the article P it has calculated is a value between the allowable minimum weight (prescribed weight Wt of article - α) and the allowable maximum weight (prescribed weight Wt of article + β) (α and β are predetermined numerical values). The control unit <NUM> determines that the article P is an accepted article when the weight W of the article P it has calculated is within the allowable weight range and determines that the article P is a rejected article when the weight W of the article P it has calculated is outside the allowable weight range.

The process by which the control unit <NUM> calculates the weight W of the article P will be described. First, a configuration of the control device <NUM> for the weight calculation process will be described with reference to <FIG> is a block diagram of a configuration of the control device <NUM> for the weight calculation process.

The control device <NUM> includes an amp <NUM>, an analog filter <NUM>, and an A/D converter <NUM>. Furthermore, the control unit <NUM> includes a signal processing unit <NUM> as a functional unit for the process for calculating the weight of the article P.

The amp <NUM> amplifies the weigh signal input from the load cell <NUM> and outputs the amplified signal to the analog filter <NUM>. The analog filter <NUM> removes unwanted high-frequency components from the amplified signal and outputs an analog signal. The A/D converter <NUM> converts the analog signal output from the analog filter <NUM> to a digital signal and outputs the digital signal to the signal processing unit <NUM>. The signal processing unit <NUM> filters the digital signal using a predetermined finite impulse response (FIR) filter (hereinafter simply called a filter). In short, the signal processing unit <NUM> uses the predetermined filter to filter the weigh signal that has been preprocessed by the amp <NUM>, the analog filter <NUM>, and the A/D converter <NUM> (hereinafter the weigh signal after being preprocessed will be called the weigh signal of the load cell <NUM>). The control unit <NUM> calculates the weight W of the article P based on the weigh signal of the load cell <NUM> filtered by the signal processing unit <NUM>.

It will be noted that, as mentioned above, in a case where the second conveyor belt 14a is conveying the article P, the load cell <NUM> detects the weight of the second conveyor <NUM> and the weight of the article P on the second conveyor <NUM> and outputs the weigh signal. For that reason, if, in a case where the second conveyor belt 14a is conveying the article P, the control unit <NUM> were to calculate the weight as is based on the weigh signal from the load cell <NUM>, the control unit <NUM> would calculate the total weight of the second conveyor <NUM> and the article P. Therefore, the control unit <NUM>, before it actually starts measuring the weight of the article P, implements a process to derive a zero point based on the weigh signal output by the load cell <NUM> in a state in which the article P is not on the second conveyor belt 14a. In other words, the control unit <NUM>, before it actually starts measuring the weight of the article P, implements in advance a process to calculate the weight of the second conveyor <NUM> that should be subtracted from the total weight of the second conveyor <NUM> and the article P on the second conveyor <NUM>.

It will be noted that the reason the signal processing unit <NUM> filters the weigh signal of the load cell <NUM> is the weigh signal of the load cell <NUM> includes noise caused by the natural vibration of the weighing apparatus <NUM> and rotational vibration of the motors (e.g., the motor used as the second drive unit 18b) and the rollers (e.g., the drive roller 144a and the follower roller 144b of the second conveyor <NUM>) being used by the weighing apparatus <NUM>.

This will be described with reference to <FIG>. The weigh signal of the load cell <NUM> is a signal that includes a vibration component (noise) with a relatively large amplitude as indicated by the dashed line in <FIG>. The weight of the article P may not be accurately calculated from the weigh signal that includes this vibration component. Therefore, the signal processing unit <NUM> uses the predetermined filter to filter (reduce the noise in) the weigh signal of the load cell <NUM> to extract a signal with little noise (generally, a signal representing just the force the article P exerts on the load cell <NUM>) such as indicated by the solid line in <FIG>.

The control unit <NUM> calculates the weight W of the article P based on the value of the difference between the weigh signal after being filtered by the signal processing unit <NUM> and the zero point. Specifically, the control unit <NUM> calculates the weight W of the article P based on the value of the difference between the weigh signal in the period in which the entire article P is on the second conveyor belt 14a (the weigh signal in the plateau portion of the solid line in <FIG>) and the weigh signal in the period in which the article P is not on the second conveyor belt 14a.

It will be noted that the frequency of the noise included in the weigh signal of the load cell <NUM> varies depending on various conditions.

For example, the frequency of the natural vibration of the weighing apparatus <NUM> is a relatively large frequency of about <NUM> to <NUM>. The frequency of the natural vibration varies depending on, for example, a length Lc1 of the second conveyor <NUM> in the conveyance direction A of the conveyance device <NUM>, a length Lc2 of the second conveyor <NUM> in the direction orthogonal to the conveyance direction A of the conveyance device <NUM> (see <FIG>), the prescribed weight Wt of the article P, and the length L1 of the article P in the conveyance direction A.

Furthermore, the frequency of the rotational vibration of the motors and the rollers is a relatively small frequency of about <NUM> to <NUM>. The frequency of the rotational vibration varies depending on, for example, the conveyance speed V of the article P (the speed of the second conveyor belt 14a), the length Lc1 of the second conveyor <NUM> in the conveyance direction A of the conveyance device <NUM>, the length Lc2 of the second conveyor <NUM> in the direction orthogonal to the conveyance direction A of the conveyance device <NUM>, the diameter of the drive roller 144a and the follower roller 144b, the number of teeth that the drive roller 144a has, the number of teeth that the motor used as the second drive unit 18b has, and the total length of the second conveyor belt 14a. For example, the frequency of the vibration of the rollers is calculated by the speed [m/s] of the second conveyor belt 14a / the roller diameter [m] × π. Furthermore, for example, the frequency of the vibration of the motors is calculated by the frequency of the vibration of the rollers × the number of teeth that the rollers have / the number of teeth that the motors have.

In this way, because the frequency of the noise included in the weigh signal of the load cell <NUM> is not always the same, the signal processing unit <NUM> is configured so that the filter setting it uses for the filtering can be varied. The reason that the filter setting that the signal processing unit <NUM> uses for the filtering can be varied is there is no single filter that can sufficiently reduce noise in all frequency bands among the filters used by the signal processing unit <NUM>.

It will be noted that the filters settable by the signal processing unit <NUM> include a combination filter. Here, a combination filter is a filter created by combining plural filters serving as bases. The advantage of using a combination filter will be described.

When a combination filter is not used, the following problems may arise. For example, a given filter F1 is able to sufficiently (e.g., to <NUM>/<NUM>,<NUM> or less) reduce the amplitude of noise with a frequency equal to or greater than a given frequency H1 [hz], but its ability to reduce the amplitude of noise with a frequency smaller than the frequency H1 [hz] markedly drops. For that reason, when the frequency of the noise in the weigh signal of the load cell <NUM> includes a frequency equal to or less than the frequency H1 [hz], sufficient noise reduction cannot be expected even when the filter F1 is used. Meanwhile, another filter F2 is able to also reduce the amplitude of noise smaller than the frequency H1 [hz], but its ability to reduce the amplitude of noise is low compared with that of the base filter F1. For that reason, if the filter F2 is used, noise with a frequency smaller than the frequency H1 [hz] may also be able to be reduced, but at the same time the amplitude of noise equal to or greater than the frequency H1 [hz] may not be able to be sufficiently reduced.

To address this, by creating a combination filter in which plural filters with different characteristics are combined such as schematically shown in <FIG> and using the combination filter to perform filtering, noise with a frequency equal to or greater than a given frequency can be sufficiently (e.g., to <NUM>/<NUM>,<NUM> or less) reduced, and also in regard to frequencies smaller than that frequency, it becomes possible to reduce to a relatively great extent the amplitude of a predetermined frequency.

To perform accurate weighing, it is important to determine which filter setting is to be used by the signal processing unit <NUM> from among numerous filter settings. However, usually, unless one is a skilled technician, it is difficult to select the appropriate filter setting from among the numerous filter settings to perform accurate weighing. Furthermore, in the case of actually operating the weighing apparatus <NUM> and determining the filter setting to be used by the signal processing unit <NUM>, a long amount of time is required to determine the filter setting.

Therefore, in the weighing apparatus <NUM> that is an example of the weighing apparatus of the invention, the control unit <NUM> determines the filter setting to be used by the signal processing unit <NUM> as follows.

The frequency of the noise included in the weigh signal of the load cell <NUM>, as mentioned above, varies depending on, for example, the properties of the article P (the prescribed weight Wt of the article P or the length L1 of the article P in the conveyance direction A), the conveyance speed V of the article P, the length Lc1 of the second conveyor <NUM> in the conveyance direction A, the length Lc2 of the second conveyor <NUM> in the direction orthogonal to the conveyance direction A, the diameter of the drive roller 144a and the follower roller 144b, the number of teeth that the drive roller 144a has, the number of teeth that the motor used as the second drive unit 18b has, and the total length of the second conveyor belt 14a. To summarize, the frequency of the noise included in the weigh signal of the load cell <NUM> varies depending on information specific to the weighing apparatus <NUM>, the speed V at which the article P is conveyed by the weighing apparatus <NUM>, and the properties of the article P.

In other words, if the information specific to the weighing apparatus <NUM>, the properties of the article P (the prescribed weight Wt of the article P or the length L1 of the article P in the conveyance direction A), and the speed V at which the article P is conveyed by the weighing apparatus <NUM> are known, the frequency of the noise included in the weigh signal of the load cell <NUM> can be inferred excluding noise caused by vibration based on environmental conditions at the location where the weighing apparatus <NUM> is installed. Moreover, here, using the control device <NUM> in weighing apparatus <NUM> having different physical configurations is not envisioned, so the information specific to the weighing apparatus <NUM> does not change. Consequently, in the weighing apparatus <NUM>, if the properties of the article P and the conveyance speed V of the article P are known, the frequency of the noise included in the weigh signal of the load cell <NUM> can be generally inferred. In other words, if the properties of the article P and the conveyance speed V of the article P are known, a filter setting suitable for the signal processing unit <NUM> to use for the filtering can be identified.

Therefore, the control unit <NUM> determines the filter setting for the signal processing unit <NUM> to use for the filtering as follows.

First, it is assumed that the storage unit <NUM> of the control device <NUM> stores information (hereinafter called first information) in which the properties of articles (the weights of the articles and the lengths of the articles in the conveyance direction A), the conveyance speeds of the articles, and filter settings suitable for these conditions are associated with each other. What is meant by a filter setting suitable for the properties of a given article and the conveyance speed of a given article is a filter setting suitable for reducing the noise in the weigh signal output by the load cell <NUM> when an article having those properties has been conveyed at that conveyance speed by the second conveyor <NUM>. The first information is information that is acquired by experiments using a test equipment of the weighing apparatus <NUM>, and/or simulations utilizing a computer, and/or performing theoretical calculations in advance and is stored beforehand in the storage unit <NUM>.

When the acquisition unit <NUM> has acquired the prescribed weight Wt of the article P, the length L1 of the article P, and the conveyance speed V of the article P (or when any of the prescribed weight Wt of the article P, the length L1 of the article P, and the conveyance speed V of the article P has been updated), the control unit <NUM> references the first information stored in the storage unit <NUM> to identify the filter setting corresponding to the prescribed weight Wt of the article P, the length L1 of the article P, and the conveyance speed V of the article P that the acquisition unit <NUM> acquired. Then, the control unit <NUM> determines the filter setting it has identified as the filter for the signal processing unit <NUM> to use for the filtering. The signal processing unit <NUM> uses the filter setting determined by the control unit to filter the weigh signal of the load cell <NUM>.

(<NUM>-<NUM>)
The weighing apparatus <NUM> includes the second conveyor <NUM> serving as an example of a conveyance unit, the load cell <NUM> serving as an example of a detection unit, the acquisition unit <NUM>, and the control unit <NUM>. The second conveyor <NUM> receives and conveys the article P. The load cell <NUM> detects the weight of the second conveyor <NUM> or, in a case where the second conveyor <NUM> is conveying the article P, the weight of the second conveyor <NUM> and the weight of the article P on the second conveyor <NUM> and outputs the weigh signal. The acquisition unit <NUM> acquires the prescribed weight Wt of the article P conveyed by the second conveyor <NUM> or the speed V at which the article P is conveyed by the second conveyor <NUM>, and the length L1 of the article P in the direction A in which it is conveyed by the second conveyor <NUM>. The control unit <NUM> determines, based on the prescribed weight Wt of the article P or the conveyance speed V of the article P and the length of the article P that the acquisition unit <NUM> has acquired, a filter setting to use to filter the weigh signal detected by the load cell <NUM>.

In particular, in this embodiment, the acquisition unit <NUM> acquires the prescribed weight Wt of the article P conveyed by the second conveyor <NUM>, the speed V at which the article P is conveyed by the second conveyor <NUM>, and the length L1 of the article P in the direction A in which it is conveyed by the second conveyor <NUM> (i.e., three parameters). The control unit <NUM> determines, based on the prescribed weight Wt of the article P, the length of the article P, and the length L1 of the article P in the direction A that the acquisition unit <NUM> has acquired, the filter setting to use to filter the weigh signal detected by the load cell <NUM>.

Because the weighing apparatus <NUM> determines the filter setting to use to filter the weigh signal based on the prescribed weight Wt of the article or the conveyance speed V of the article P and the length L1 of the article P in the conveyance direction A that it has acquired, it is possible to determine an appropriate filter setting with which a high weighing accuracy can be realized even if one is not a knowledgeable and experienced technician.

(<NUM>-<NUM>)
The weighing apparatus <NUM> includes the storage unit <NUM>. The storage unit <NUM> stores information in which the prescribed weight of the article P or the conveyance speed V of the article P, the length of the article P, and the filter setting are associated with each other. In particular, in this embodiment, the storage unit <NUM> stores information in which the prescribed weight of the article P, the conveyance speed V of the article P, the length L1 of the article P in the conveyance direction A, and the filter setting are associated with each other. The control unit <NUM> determines the filter setting based also on the information stored in the storage unit <NUM>.

In the weighing apparatus <NUM>, the prescribed weight of the article P or the conveyance speed V of the article P, the length L1 of the article P in the conveyance direction A, and the appropriate filter setting are associated with each other and stored in the storage unit <NUM>, so it is possible to determine the appropriate filter setting even without conducting an actual operation of the weighing apparatus <NUM>.

Example modifications of the embodiment will be described below. It will be noted that the example modifications described below may be combined as appropriate where they are not mutually contradictory.

In the above embodiment, the acquisition unit <NUM> acquires the prescribed weight Wt of the article P, the length L1 of the article P in the conveyance direction A of the conveyance device <NUM>, and the speed V at which the article P is conveyed by the conveyance device <NUM>.

However, the acquisition unit <NUM> need not acquire all of these. For example, in a case where the conveyance speed of the conveyance device <NUM> is not variable, the acquisition unit <NUM> need not acquire the conveyance speed of the conveyance device <NUM>.

Furthermore, for example, in a case where the articles the weighing apparatus <NUM> handles are the same, the acquisition unit <NUM> need not acquire the prescribed weight of the article P.

In the above embodiment, using the control device <NUM> in weighing apparatus having different physical configurations is not envisioned, but the control device <NUM> is not limited to this. The control device <NUM> may also be used in weighing apparatus having different physical configurations (having different specifications).

It will be noted that the frequency of the noise included in the weigh signal of the load cell <NUM>, as mentioned above, varies depending on the information specific to the weighing apparatus <NUM>, the properties of the article P, and the conveyance speed V of the article P. For that reason, in a case where the control device <NUM> is also used in weighing apparatus having different physical configurations, it is preferred that the control unit <NUM> also be provided with the information specific to the weighing apparatus <NUM> in order to determine the filter setting for the signal processing unit <NUM> to use.

Therefore, in a case where the control device <NUM> is used in weighing apparatus having different physical configurations, it is preferred that the acquisition unit <NUM> further acquire information relating to vibrational characteristics of a constituent part/constituent parts of the weighing apparatus.

Although this is not intended to limit the content of the information, for example, the information relating to the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus <NUM> includes information about the length Lc1 of the second conveyor <NUM> in the conveyance direction A, information about the length Lc2 of the second conveyor <NUM> in the direction orthogonal to the conveyance direction A, information about the rigidity of members used in the weighing apparatus <NUM>, information about the diameter of the drive roller 144a and the follower roller 144b, information about the number of teeth that the drive roller 144a has, information about the number of teeth that the motor used as the second drive unit 18b has, and information about the total length of the second conveyor belt 14a. It will be noted that the acquisition unit <NUM> need not acquire all the items of information relating to the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus <NUM> exemplified here. For example, in regard to an item that has a relatively small effect on the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus <NUM>, the acquisition unit <NUM> need not acquire information about that item.

Furthermore, the information relating to the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus <NUM> may also be information representing the type of the weighing apparatus (e.g., the model number representing the type of weighing apparatus).

In a case where the acquisition unit <NUM> acquires the information relating to the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus, it is preferred that the storage unit <NUM> store information (hereinafter called first information) in which the properties of articles (the weights of the articles or the lengths of the articles in the conveyance direction A), the conveyance speeds of the articles, the information relating to the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus, and filter settings suitable for these conditions are associated with each other. What is meant by a filter setting suitable for the properties of a given article, the conveyance speed of a given article, and the vibrational characteristics of the constituent part/constituent parts of a given weighing apparatus is a filter setting suitable for reducing the noise in the weigh signal output by the load cell <NUM> when an article having those properties has been conveyed at that conveyance speed by the second conveyor <NUM> in the weighing apparatus corresponding to the information relating to the vibrational characteristics of its constituent part/constituent parts.

Then, when the acquisition unit <NUM> has acquired the prescribed weight Wt of the article P or the conveyance speed V of the article P, the length L1 of the article P, and the information relating to the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus (or when any of these pieces of information has been updated), the control unit <NUM> references the first information stored in the storage unit <NUM> and identifies the filter setting corresponding to the prescribed weight Wt of the article P or the conveyance speed V of the article P, the length L1 of the article P, and the information relating to the vibrational characteristics of the constituent part/constituent parts of the weighing apparatus that the acquisition unit <NUM> has acquired. Then, the control unit <NUM> determines the filter setting it has identified as the filter for the signal processing unit <NUM> to use for the filtering. The signal processing unit <NUM> uses the filter setting determined by the control unit to filter the weigh signal of the load cell <NUM>.

Furthermore, even if the control device <NUM> is not used in weighing apparatus having different physical configurations (having different specifications), the control device <NUM> may be configured as described in this example modification B. When the control device <NUM> is configured in this way, even if, for example, the specifications of some parts have been changed due to replacement of those parts, an appropriate filter setting corresponding thereto can be determined.

The weighing apparatus <NUM> of the above embodiment has the conveyance device <NUM>, the detection device <NUM>, and the control device <NUM>, but the weighing apparatus <NUM> may also be an apparatus having configurations other than these. For example, in the above embodiment, an example is described where a sorting device separate from the weighing apparatus <NUM> is disposed downstream of the weighing apparatus <NUM>. However, the weighing apparatus <NUM> may also have a sorting mechanism that sorts the articles P based on the weighing results of the articles P.

In the above embodiment, a FIR filter was described as an example of the filter, but the filter type is not limited to a FIR filter and may be another type of filter capable of filtering the weigh signal.

In the above embodiment, the weighing apparatus <NUM> equipped with the load cell <NUM> that has a strain gauge as a detection unit (weight sensor) is described. However, the type of detection unit that the weighing apparatus has is not limited to a load cell using a strain gauge. For example, the load cell <NUM> may also be a hydraulic load cell or a pneumatic load cell. Furthermore, the detection unit may also be a weight sensor other than a load cell type, such as a tuning fork vibration type of weight sensor, an electromagnetic balance type of weight sensor, or a capacitive type of weight sensor.

It will noted that in a case where there is the potential for different types of detection units to be used, the frequency of the noise included in the weigh signal output by the detection unit may vary. Furthermore, in a case where the weighing capacity and/or the spring constant are different, the frequency of the noise included in the weigh signal output by the detection unit may vary, even when the detection unit is the same type (e.g., even when it is a load cell using a strain gauge).

Therefore, in a case where the type of the detection unit is different (here, a case where the type of the detection unit is different includes a case where the detection unit is the same type but has a different weighing capacity and/or spring constant), it is preferred that the acquisition unit <NUM> of the control device <NUM> acquire information relating to the type of the detection unit.

In a case where the acquisition unit <NUM> acquires the information relating to the type of the detection unit, it is preferred that the storage unit <NUM> store information (hereinafter called first information) in which the properties of articles (the weights of the articles or the lengths of the articles in the conveyance direction A), the information relating to the type of the detection unit, the conveyance speeds of the articles, and/or the information relating to the vibrational characteristics of the constituent parts of the weighing apparatus, and filter settings suitable for these conditions are associated with each other. What is meant by a filter setting suitable for conditions is a filter setting suitable for reducing noise in the weigh signal output by the detection unit when the article has been conveyed by the second conveyor <NUM> in those conditions.

Then, when the acquisition unit <NUM> has acquired the prescribed weight Wt of the article P or the conveyance speed V of the article P, the length L1 of the article P, the information relating to the type of the detection unit, and, as needed, the information relating to the vibrational characteristics of the constituent parts of the weighing apparatus (or when any of these pieces of information has been updated), the control unit <NUM> references the first information stored in the storage unit <NUM> and identifies the filter setting corresponding to the information that the acquisition unit <NUM> has acquired. Then, the control unit <NUM> determines the filter setting it has identified as the filter for the signal processing unit <NUM> to use for the filtering. The signal processing unit <NUM> uses the filter setting determined by the control unit to filter the weigh signal of the load cell <NUM>.

The present invention can be widely applied to weighing apparatus that weigh an article as it is being conveyed, and is useful.

Claim 1:
A weighing apparatus (<NUM>) comprising:
a conveyance unit (<NUM>) configured to receive and convey an article;
a detection unit (<NUM>) configured to detect a weight of the conveyance unit (<NUM>) or, in a case where the conveyance unit (<NUM>) is conveying the article, the weight of the conveyance unit (<NUM>) and a weight of the article on the conveyance unit (<NUM>) and output a weigh signal;
an acquisition unit (<NUM>) configured to acquire:
a prescribed weight of the article conveyed by the conveyance unit (<NUM>),
a speed at which the article is conveyed by the conveyance unit (<NUM>) and
a length of the article (L1) in a direction in which it is conveyed by the conveyance unit (<NUM>); and
a control unit (<NUM>) configured to determine, based on the prescribed weight of the article, the conveyance speed of the article (V) and the length of the article (L1) that the acquisition unit (<NUM>) has acquired, a filter setting to use to filter the weigh signal detected by the detection unit (<NUM>).