JP2001349771A - Weighing device and commodity treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weighing device for performing automatic taring independently of the size of a tray in use for simple weighing work and eliminating the possibility of missing the taring. SOLUTION: The weighing device for measuring the weight of a commodity M placed on a tray T together with the tray T and subtracting the weight of the tare preset and registered for every type of tray from a measurement value for the tare to find the net weight of the commodity M, comprises detecting means for detecting information for the size of the tray T, means for finding the weight of the tray T in accordance with the detected information for the size of the tray T, and means for storing the weight of a sub-material attached to the commodity. The total of the weight of the tray and the weight of the sub-material is defined as the weight of the tare to find the net weight of the commodity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weighing device and an article processing device provided with the weighing device, and more particularly to a taring device.

[0002]

2. Description of the Related Art Food products and the like in a supermarket are placed on a tray and packaged with a film together with the tray, and a label indicating the net weight and price of the product is attached to the film. The net weight is obtained by subtracting the tare weight (tray weight or (tray weight) + (film weight)) from the weighed value including the tare weighed for each tare (for example, see Japanese Patent Publication No. 3-48451). Here, conventionally, a tray to be used is determined for each type of product, and therefore, the tare weight is determined for each product.

[0003]

However, in recent years, the needs of consumers have been diversified, and there are products having the same content but different contents and numbers. For example, there are cases in which two pieces of “brittle fillet” and four pieces of “brittle fillet” are sold. In such a case, the size of the tray is also two types, and therefore, the tray No. Must be entered to perform tare, which makes the weighing operation cumbersome.

Further, in the case of products such as "eel kabayaki" and "sashimi", sub-materials such as "sag sauce", "wasabi" and "soy sauce" are stored in a tray together with the products, and are weighed and valued. Is performed. In this case, since it is necessary to subtract the weight of the auxiliary material in addition to the tare, the operation of taring is further troublesome. In addition, the amount of the sub-material changes according to the amount of the product, for example, 30 g in the case of one eel and 60 g in the case of two eels,
The type of tray also changes according to the quantity of goods, so that the work of taring becomes more troublesome. In addition, there is a case where the operator forgets the work of taring.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and can automatically perform a taring operation regardless of the size of a tray to be used to easily carry out a weighing operation, and forgetting the taring operation. It is an object of the present invention to provide a weighing device and a product processing device that are not likely to be performed.

[0006]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, the weight of a product placed on a tray is measured for each tray, and the net weight of the product is determined based on the measured value. In the weighing device, detecting means for detecting information on the dimensions of the tray, means for determining the weight of the tray based on the detected dimensional information of the tray, and means for storing the weight of the auxiliary material attached to the product Wherein the total weight of the tray weight and the auxiliary material weight is used as the tare weight to determine the net weight of the product.

According to the first aspect of the present invention, information on the dimensions of the tray is detected, the weight of the tray is determined based on the dimensional information, and the weight of the tray and the weight of the auxiliary material attached to the product are summed up. Since the weight is determined, even when a plurality of trays are used for one product, the tray No. Without typing
Tare including the weight of the secondary material can be automatically performed. Therefore, the weighing operation is simplified, and there is no fear of forgetting the tare. For the tray weight, for example, the tray weight stored in advance may be read out, or the tray weight may be obtained from the tray size and the weight per unit area.

According to a second aspect of the present invention, in the weighing device of the first aspect, the weight of the tray is stored for each type of the tray, and the type of the tray is determined based on the detected dimensional information of the tray. And identifying the tray weight based on the identified type of tray.

According to the second aspect of the present invention, the type of tray is specified based on the detected dimensional information of the tray, and the tray weight stored in advance for each type of tray is read. Therefore, for example, by storing an empty tray on a weighing device and storing the measured value as the tray weight, the accurate tray weight can be used in taring, and the accurate net weight can be obtained. it can.

According to a third aspect of the present invention, there is provided a weighing device for measuring the weight of a product placed on a tray for each tray and obtaining a net weight of the product based on the weighed value, and detects information relating to the dimensions of the tray. Detecting means, means for determining the weight of the tray and the weight of the film packaging the tray based on the detected dimensional information of the tray, and means for storing the weight of the auxiliary material attached to the product, The total weight of the tray weight and the sub-material weight is set as a tare weight, and a net weight of the product is obtained.

According to the third aspect of the present invention, information relating to the dimensions of the tray is detected, and the weight of the tray and the weight of the film wrapping the tray are determined based on the dimensional information. When the weight of the tray and the product is wrapped with a film and then weighed, a plurality of trays may be used for one product even if the tray and the product are weighed. , The tare including the weight of the auxiliary material can be automatically performed. Therefore, the weighing operation is simplified, and there is no fear of forgetting the tare. The weight of the tray and the weight of the film may be, for example, a value stored in advance, or the weight of the tray may be determined from the size of the tray and the weight per unit area. The weight of the film may be determined from the weight of the film.

According to a fourth aspect of the present invention, in the weighing device according to the third aspect, the weight of the tray and the weight of the film wrapping the tray are stored for each type of the tray, and the detected weight of the tray is stored. The type of the tray is specified based on the dimensional information, and the weight of the tray and the weight of the film are read out based on the specified type of the tray.

According to the fourth aspect of the invention, the type of tray is specified based on the detected dimensional information of the tray, and the tray weight and the film weight stored in advance for each type of tray are read. Therefore, for example, a value obtained by actually placing an empty tray on a weighing device and storing the measured value as the tray weight, and storing the weight of the film determined by the type of the tray as the film weight can be obtained. Weight and film weight can be used to get the exact net weight.

[0014] The invention according to claim 5 provides the invention according to claims 1 to 4.
In the weighing device according to any one of the above, the weight of the auxiliary material is stored in advance for each product number.

According to the fifth aspect of the present invention, the auxiliary material weight is stored in advance for each product number (call number). Is read out. For this reason, the weighing operation is simplified, and there is no fear of forgetting to subtract the weight of the auxiliary material from the net weight.

[0016] The invention according to claim 6 is the invention according to claims 1 to 4.
In the weighing device according to any one of the above, the weight of the auxiliary material is stored in advance for each product number and for each tray number.

According to the sixth aspect of the present invention, the amount of the sub-material depends on the amount of the product, for example, 30 g for one eel and 60 g for two eels. And the type of tray also changes according to the quantity of the product, the weight of the auxiliary material is changed to the product number (call number).
Is stored in advance for each tray and for each tray number (tray No.). When a product number is entered in the operating means and the type of tray to be used is specified, the tray number of the tray is made to correspond to that. The stored sub-material weight is automatically read. For this reason, there is no fear of forgetting to subtract the weight of the auxiliary material from the net weight, and the weighing operation can be easily performed by automatically performing taring regardless of the size of the tray to be used.

According to a seventh aspect of the present invention, there is provided a product processing apparatus comprising the weighing device according to any one of the first to sixth aspects.

According to a seventh aspect of the present invention, the weighing device according to any one of the first to sixth aspects is linked with a label printer to process goods such as a weighing device and a weighing and packaging device. The device can be configured.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 and FIG. 2 show a weighing / packaging / pricing device which is an example of a product processing device. First, the weighing / packaging mechanism of the device will be described.

In FIG. 2, reference numeral 100 denotes a weighing conveyor, 2
00 is a packaging device. The weighing conveyor 100 includes a weight detector 101 such as a load cell that weighs the weight of the product M including a tare, and a plurality of pulleys 102 laid over a pair of pulleys 102 supported on the weight detector 101. It has a drive belt 103. To each of these drive belts 103, a claw-shaped projection 104 for pushing an end of a tray (tare) T and feeding the product M to the packaging device 200 side is fixed. Therefore, the placed product M is sent to the elevator mechanism 201 together with the tray T while sliding on the transport surface 105 after the weight is measured.

The elevator mechanism 201 is disposed immediately below the packaging station S,
It can be moved up and down vertically. When the product M is supplied from the weighing conveyor 100, the elevator mechanism 201 rises and lifts the product M to the packaging station S.

On the other hand, prior to the wrapping operation, the stretched film F is transported to the wrapping station S by the transfer mechanism 20.
2,202. This film F
When the product M is pushed up, it comes into close contact with the upper surface of the product M. In this state, the film folding mechanism 203 includes a pair of left and right folding plates 204 and 204 of FIG.
, A round bar-shaped front folding member 206, a pusher 207
According to (FIG. 1), the front and rear and left and right side edges of the film F are folded into the bottom side of the tray T to package the product M.

In FIG. 1, inside the main body frame 20,
A plurality of film rolls Fr having different widths F2 (FIG. 3) are accommodated, and any one of the film rolls F is stored.
By selecting r, the film F can be unwound into the packaging station S. Above the packaging station S, a label pasting machine 13 is provided. The label sticking machine 13 sticks the label issued from the label printer 12 on the surface of the film F at the packaging station S in FIG. The label printer 12 and the label pasting machine 13 of FIG. 1 are movably supported in the left-right direction X and the depth direction Y of FIG. 2 by the upper support frame 21, and a pasting head (not shown) is arranged around a vertical axis. It is supported so as to be freely rotatable, and a label sticking position and a label sticking posture can be selected.

In FIG. 2, an ultrasonic range finder 1 and a CCD camera (imaging device) are provided above the weighing conveyor 100.
2 are provided. The ultrasonic range finder 1 transmits an ultrasonic pulse having a predetermined frequency downward, receives a reflected wave from the product M and the tray T, and determines the time between the reception of the product M and the product M. The shortest distance to the tray T is calculated and output to the microcomputer (microcomputer) 3 in FIG. The microcomputer 3, the ultrasonic distance meter 1, and the CCD
The camera 2 constitutes dimension information detecting means (appearance information detecting means) for detecting dimension information of the tray T. The CC
The D camera 2 includes a tray T placed on a predetermined area on the weighing conveyor 100 at a predetermined angle from a predetermined position above.
Is imaged as shown in FIG. 5A, and luminance information (imaging information) is output.

In FIG. 4, in addition to the above-described ultrasonic range finder 1 and CCD camera 2, a microcomputer 3, a measuring unit 106, a touch screen (input operation unit) 10, and a stroke key unit are connected via an interface (not shown). (Input operation means) 11, a label printer 12, a controller 14 with weighing and packaging value, and the like are connected. The microcomputer 3
Includes a CPU 4 and a memory 5. The CPU
Reference numeral 4 includes an image processing unit 40, a dimension correcting unit 41, and a tray specifying unit 42. On the other hand, the memory 5 includes a product information storage unit 50 and a tray information storage unit 51.

FIG. 6A shows the merchandise information storage unit 50.
No. of product call No. In correspondence with the product, one or more tray Nos. To be used besides the product name and unit price for each product. Is stored. The information of the product name and the unit price is used as label print information.

On the other hand, the tray information storage unit 51 shown in FIG. 6B stores, for each tray, a tray size including a tray width (long side dimension) W and a depth (rectangular side dimension) D, and various types of information. The processing content of the product is stored. The processing contents include a tray weight Wt for taring and a film No. determined by the depth of the tray. (Film width), film length (cut length) determined by the width of the tray, label sticking position and sticking posture determined by the size of the tray. The information in the product information storage unit 50 and the tray information storage unit 51 is input from the touch screen 10 and the stroke key unit 11 in FIG.

The image processing means 40 shown in FIG. 4 detects the position of the apparent planar edge of the tray T from the luminance information input from the CCD camera 2 by the method described below. From the position of the edge, the apparent size of the tray T is calculated. The first image storage unit 52 of the memory 5 previously stores an image of the weighing conveyor 100 in a state where the tray T is not placed thereon, while the second image storage unit 53 stores the image of FIG. An image in a state where the tray T is placed is stored. The image processing unit 40 in FIG. 4 obtains the position of the edge Te on the tray T from the change in the brightness of the first and second image storage units 52 and 53.

On the other hand, the first and second reference lines C1 and C2 are arranged vertically and horizontally in the image pickup area A of the CCD camera 2 shown in FIG.
Are set, and the reference lines C1 and C2 and the imaging area A
The intersection O _N the end of, based on the distance between the intersection P _N of the two reference lines C1, C2 and edge Te, the tray T
Is calculated. For example, the apparent width Wa of the tray T is calculated by the following equation (1). Wa = W ₀ − (W ₁ + W ₂ ) (1)

Next, a method for obtaining the actual size of the tray T from the apparent size of the tray T will be described. As shown in FIG. 5B, when an image of a tray having a height H is taken and the planar dimension W of the tray T is measured, an apparent dimension Wa is a measured value. Here, the planar dimension W and the apparent dimension Wa of the actual tray T are expressed by the following equation (2). Wa: W = Ha: (Ha-H) (2) where Ha-H is the distance (height) from the imaging device to the edge Te of the tray Ha: the distance (height) from the imaging device to the transport surface 105 From the above equation (2), the actual dimension W of the tray T is expressed by the following equation (3). W = Wa · (Ha−H) / Ha (3) Therefore, by knowing the distance (Ha−H) from the imaging device to the edge Te of the tray, it is possible to know the actual dimensions of the tray.

The dimension correcting means 41 shown in FIG. 4 calculates the apparent dimension (width) Wa of the tray T shown in FIG. 5B by the height (Ha-H) to the tray in accordance with the equation (3). After correction, tray sizes W and D are obtained.

The tray specifying means 42 shown in FIG. 4 calculates the size (measured value) of the tray T obtained by the detection and calculation.
W and D are compared with the registered setting values of the tray stored in FIG. 6B. (Tray type) is specified. First, the tray specifying unit 42 sets the product call No. input from the stroke key unit 11. Tray No. corresponding to And each tray N read out
o. For each tray width W and depth D, the measured value and the set registration value are compared, and the absolute value ΔW of the difference for the width W and the absolute value ΔD of the difference for the depth D are determined. Subsequently, the tray specifying means 42 sets the tray having the smallest sum of the absolute values ΔW + ΔD as a candidate to be specified.

Next, the tray specifying means 42 determines whether or not the absolute values ΔW and ΔD are both within a predetermined measurement error range (threshold) ΔA. If the tray No. is within the tray No. Judge that it is. On the other hand, if one or both of the absolute values ΔW and ΔD are larger than the predetermined measurement error range ΔA, the tray specifying means 42
o. Is specified, the same operation as described above is performed for all types of trays, and the tray No. is selected from all the types of trays. To identify. In addition, tray No. is selected from all trays. If you cannot specify the tray, do not specify the tray.

The CPU 4 has a tray No. Is specified from the tray information storage unit 51 in FIG. The processing contents of the product are read out, and the processing conditions are output to the controller 14 with the weighing and packaging value. CPU4
Indicates the specified tray No. Is subtracted from the measured value to calculate the net weight Wc of the product M, and the net weight Wc
Is printed by the label printer 12. In addition, the controller 14 with the weighing / packaging value specifies the specified tray No. Film No. And the product M is packaged based on the film length. The label sticking machine 13 sticks a label according to the output sticking position and sticking posture. The CPU 4 in FIG. If is not specified, the processing content of the product is calculated according to a predetermined arithmetic expression, and the processing content is output to the controller 14 with the weighing and packaging value. For example, the microcomputer 3 obtains the tray weight Wt from the detected width W, depth D and height H of the tray by the following equation (4). Wf is calculated by the following (5)
The net weight Wc is obtained by subtracting the tray weight Wt or the tray weight Wt and the film weight Wf from the weight including the tare. Wt = Ct · {W · D + 2H · (W + D)} (4) where Ct: weight of tray per unit area Wf = Cf · {2 · (W + H) + L} (5) , Cf: film weight per unit length L: film overlap length

Next, the operation of the above configuration will be described. First, a registration mode is set in advance, and a product call N
o. , Product name, unit price and tray No. Etc.
Settings are registered from the touch screen 10 and the stroke key unit 11 for each product. Each tray No. The tray depth, width, tray weight Wt, film No. , Film length, sticking position and sticking posture, etc.
Register settings from. As the tray weight Wt, a value measured by placing an empty tray T on the weighing conveyor 100 can be registered.

On the other hand, when packaging a product, the packaging mode is set first. Next, the operator calls the number of the product to be packed. Is input, and the tray T on which the product M is placed is placed on the weighing conveyor 100, the weighing means 106 converts the output from the weight detector 101 into a weight, and
Output to When the weight signal is stabilized (the weight detector 101 is stabilized), the microcomputer 3 captures the luminance information from the CCD camera 2 and the height information from the ultrasonic distance meter 1.

Thereafter, the CPU 4 detects the edge Te of the tray based on the above-described method, obtains the apparent size of the tray from the edge Te, corrects the apparent size with height information, and obtains the width of the tray. Find W and depth D,
Identify the tray. The microcomputer 3 uses the specified tray N
o. Is subtracted from the weighed value including the tare, and the net weight is obtained.
0 and output to the label printer 12. The label printer 12 prints the net weight and the product name on the label and issues the label. The issued label is affixed to the product which is stretch-wrapped together with the tray T.

As described above, according to the present apparatus, the type of the tray is specified by comparing the detected size information of the tray with the registered size information, and the tray weight Wt is determined based on the specified type of the tray to obtain a net weight. Since the weight is obtained, even when a plurality of types of trays are used for one product, the tray No. , The net weight can be obtained and the net weight can be printed. Therefore, the workability of weighing and pricing is improved. In addition, there is no risk of forgetting to subtract (tare) the tare weight Wv.

By the way, even if the tray is not specified or the tray cannot be specified, it is not possible to obtain the tray weight Wt from the above-mentioned formula (10), that is, from the size of the tray and the weight per unit area. it can. However, in this case, it is inevitable that an error occurs in the tray weight Wt. On the other hand, by specifying the type of tray as in the present embodiment, the accurate tray weight Wt weighed in advance by the weighing conveyor 100 can be known. Therefore,
An accurate net weight Wc is obtained.

By the way, the tray to be used is determined to some extent in advance depending on the type of the product (product name or the like). Here, in the above-described embodiment, first, the product call No. The tray is specified by selecting a tray from the types of trays corresponding to. Therefore, the product call No. Since the candidates for the tray specified by the above are narrowed down in advance, the specification of the tray is accurate and quick. As a result, an accurate net weight Wc can be obtained quickly.

By the way, the product information storage unit 5 shown in FIG.
If the dimensions of the trays registered for each of the products 0 are similar to each other, there is a possibility that the identification of the tray may be erroneous. Therefore, the same product call No. May be registered on condition that they have a dimensional difference equal to or greater than a predetermined value. For example, at least one of the tray width W and depth D is the same product call No. Only when there is a dimensional difference greater than or equal to a predetermined value with respect to the width W and the depth D of the other tray registered in the corresponding product call No. May be stored (registered) in the product information storage unit 50.

By the way, for products such as "eel kabayaki" and "sashimi", auxiliary materials such as "sag sauce", "wasabi" and "soy sauce" are stored in a tray together with the products, and weighed and valued. May be performed. In this case, it is necessary to subtract the weight of the secondary material in addition to the tare. On the other hand, the amount of the secondary material is, for example, 30 g in the case of one "eel",
In the case of two "eels", the weight varies according to the quantity of the product, such as 60 g. On the other hand, the type of tray also changes according to the amount of goods. Therefore, as shown in FIG. 7A, the tray No. is stored in the product information storage unit 50 in advance. The weight of the auxiliary material may be stored together with the weight, and the weight of the tray and the auxiliary material may be subtracted from the measured value to determine the net weight.

In the above embodiment, stretch wrapping is performed after weighing. However, as shown in FIG. 8A, weighing may be performed after stretch wrapping. For example, FIG.
As shown in (b), in a packaging weighing / applying device in which a carry-in conveyor 110 is provided upstream of the weighing conveyor 100 and a label pasting machine 13 is provided on a conveyor 120 downstream of the weighing conveyor 100, the packaging is carried out on the carry-in conveyor 110. Put the finished product. In the weighing and packaging apparatus, the tare weight Wv
It is necessary to obtain the net weight Wc by subtracting the film weight Wf from the measured value in addition to the tray weight Wt. In such a case, the weight of the film is determined to some extent by the size of the tray, that is, the type of the tray. Therefore, as shown in FIG. 7B, the tray information storage unit 51 stores the film weight Wf in addition to the tray weight Wt in the tray No. After the microcomputer 3 specifies the tray, the tray weight Wt and the film weight Wf are subtracted from the weighed value including the tare to obtain a net weight Wc, and a label printed with the net weight Wc is obtained. It sticks by the label sticking machine 13 of FIG.8 (b). In addition, when it is necessary to subtract the film weight Wf, the tray cannot be specified.
Alternatively, when the tray is not specified, the microcomputer 3 obtains the tray weight Wt and the film weight Wf by the above-described equations (4) and (5).

The present invention relates to a commodity processing apparatus in which a label printer is linked to an electronic weigher or a weighing apparatus in addition to the weighing / packaging / pricing apparatus (Japanese Patent Laid-Open No. 6-92).
338).

In the above embodiment, the ultrasonic distance meter 1
And the dimensions of the tray were detected using the CCD camera 2
In the present invention, the mechanism for detecting the size of the tray is not limited. For example, when a carry-in conveyor is provided upstream of the weighing conveyor 100 shown in FIG. 1 (see Japanese Patent Application Laid-Open No. 7-257524), a large number of reflection-type photoelectric detectors 300 are provided as shown in FIG. The width W of the tray T is calculated from the number of the detectors 300 on which the reflected light is incident while moving on the carry-in conveyor, while the transmission-type photoelectric detectors 301 and 30 are calculated.
2, the depth D of the tray T may be calculated from the time during which the light is shielded and the transport speed while the tray T moves on the carry-in conveyor 100. When a centering device for centering the tray is provided, or when a pusher for pushing the tray from behind is provided, the dimensions of the tray may be detected from the stroke of the centering device or the pusher. Also, the height of the tray may be detected by arranging a large number of photoelectric detectors vertically.
Further, without directly detecting the actual dimensions of the width W and the depth D, the apparent planar dimensions and the area (information on the dimensions) of the tray captured by the piezoelectric sensor or the CCD camera are registered. Alternatively, the tray to be used may be specified by comparing with the above, and the pre-registered tare weight may be read from the specified tray.

When calculating the film weight Wf,
The film weight Wf may be corrected in consideration of the arrangement height of the products.

[0048]

According to the present invention, information relating to the dimensions of the tray is detected, and the weight of the tray is determined based on the dimensional information.
Since the tare weight is obtained by summing this and the weight of the auxiliary material attached to the product, even when a plurality of trays are used for one product, the tray No. , The tare including the weight of the auxiliary material can be automatically performed. Therefore, the weighing operation is simplified, and there is no fear of forgetting the tare.

In the case where the tray and the product are weighed after being wrapped with a film, information relating to the dimensions of the tray is detected, and the weight of the tray and the weight of the film for packaging the tray are determined based on the dimensional information. This is added to the weight of the auxiliary material attached to the product to determine the tare weight, so when using multiple trays for one product,
Tray No. , The tare including the weight of the auxiliary material can be automatically performed. Therefore, the weighing operation is simplified, and there is no fear of forgetting the tare.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a weighing / packing and pricing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the same mechanism.

FIG. 3 is a perspective view showing a packaging method.

FIG. 4 is a schematic configuration diagram of a weighing / packaging and pricing device.

FIG. 5 is a diagram for explaining a method of calculating the width and depth of a tray from apparent dimensions.

FIG. 6 is a table showing an example of contents stored in a product and tray information storage unit.

FIG. 7 is a chart showing the modification.

FIG. 8 is a conceptual diagram showing a schematic mechanism of another product processing apparatus.

FIG. 9 is a perspective view showing another method for detecting the tray size.

[Explanation of symbols]

 T: Tray (Tare) M: Product W: Tray width D: Tray depth H: Tray height

Claims (7)

[Claims] 1. A weighing device that weighs the weight of a product placed on a tray for each tray and obtains a net weight of the product based on the weighed value. Means for determining the weight of the tray based on the dimensional information of the tray, and means for storing the weight of the auxiliary material attached to the product, wherein the total weight of the tray weight and the auxiliary material weight is tared. A weighing device, wherein a net weight of the product is obtained as a weight. 2. A tray weight is stored for each tray type, a tray type is specified based on the detected tray size information, and the tray weight is read out based on the specified tray type. The weighing device according to claim 1, wherein: 3. A weighing device for weighing the weight of a product placed on a tray for each tray and obtaining a net weight of the product based on the weighed value, wherein: a detecting means for detecting information relating to the dimensions of the tray; Means for determining the weight of the tray and the weight of the film wrapping the tray based on the dimensional information of the tray, and means for storing the weight of the auxiliary material attached to the commodity, the tray weight, A weighing device characterized in that a net weight of the product is obtained by setting a total weight of the auxiliary material weight and a tare weight as a tare weight. 4. A method for storing the weight of a tray and the weight of a film wrapping the tray for each type of tray, specifying the type of tray based on the detected dimensional information of the tray, and specifying the type of the specified tray. The weighing device according to claim 3, wherein the weight of the tray and the weight of the film are read based on a type. 5. The weighing device according to claim 1, wherein the weight of the auxiliary material is stored in advance for each product number. 6. The weighing device according to claim 1, wherein the weight of the auxiliary material is stored in advance for each product number and for each tray number. 7. A merchandise processing apparatus comprising the weighing device according to any one of claims 1 to 6.