WO2020238757A1

WO2020238757A1 - Device and method for improving weighing reliability

Info

Publication number: WO2020238757A1
Application number: PCT/CN2020/091605
Authority: WO
Inventors: Shenhui Wang; Zhiqiang Wang; Song Zhang
Original assignee: Mettler-Toledo (Changzhou) Measurement Technology Ltd.; Mettler-Toledo (Changzhou) Precision Instruments Ltd.; Mettler-Toledo International Trading (Shanghai) Co., Ltd.
Priority date: 2019-05-29
Filing date: 2020-05-21
Publication date: 2020-12-03
Also published as: CN112013941A

Abstract

A device and a method for improving weighing reliability comprises a light source (11) arranged on a side surface of a frame of weighing equipment (1) and used for projecting light beams (13) to the outside of the weighing equipment (1). The device also comprises an image capture device (12) arranged on the side surface on which the light source (11) is arranged and the image capture device (12) is used for capturing a projection image of the light beams (13) on a projection surface. The device further comprises an image processor used for validating whether the projection image is incomplete and thereby determining whether an object to be weighed overlaps the ground surface or the frame of the weighing equipment (1). The device and the method for improving weighing reliability can improve the application range of an exceeding detection and reliability in the weighing process.

Description

DEVICE AND METHOD FOR IMPROVING WEIGHING RELIABILITY

BACKGROUND OF THE INVENTION Technical Field

The invention relates to a weighing equipment and in particular to a device and a method for improving weighing reliability.

Background Art

In some weighing application scenarios where the dimensions of an object to be weighed exceed length of bearing surface of the weighing equipment such as an electronic scale, a part of the object to be weighed can extend beyond the bearing surface of the electronic scale. If the part of the object to be weighed extending beyond the bearing surface of the electronic scale overlaps the ground or a table top, part of the weight of the object to be weighed will fall outside the bearing surface of the electronic scale, thus causing improper use of the electronic scale, further affecting weighing reliability. During weighing process, the improper use of an electronic scale caused by the overlapping described above will directly lead to incorrect weighing results, thus causing adverse consequences.

If an overlap condition can be detected at the start of the weighing application of the electronic scale, the subsequent steps involving a weighing operation with an overlap condition can be avoided. By validating an object to be weighed for an overlapping condition, the weight of the weighed object is ensured to completely fall on the bearing surface of the electronic scale, which will effectively avoid adverse consequences caused by the overlap condition, thereby improving weighing reliability of the electronic scale.

Patent prior art reference CN 102763120 B discloses a scanner-scale system and a method for monitoring the periphery of an electronic scale. The system is provided with a light source, a light guide and a detector at a side edge of a weighing plate. During weighing, it is determined whether the light path of the light beams is blocked by a part of the object to be weighed based on whether the light beams from the light source transmitted through the light guide can be received by the detector, which in turns determines whether the object to be weighed exceeds the size of the bearing surface of the electronic scale.

The aforementioned prior art technical solution can be used to detect whether a part of an object to be weighed exceeds a bearing surface of an electronic scale. However, since its light source, light guide and detector are arranged close to the side edge of the weighing plate, it can only detect objects with relatively regular shapes. For irregularly shaped objects to be weighed, for example, being curved to a certain degree, if the part that exceeds the bearing surface of the electronic scale just bypasses the detection range of the light path and overlaps the ground or table top, the above solution fails to work effectively, thus affecting the reliability of subsequent weighing results.

In addition, if part of the object extends beyond the bearing surface of the electronic scale and blocks the light path, while at the same time, there is no overlap between said part and the ground or table top, the above solution may lead to false positives. A high rate of frequent false positives will strongly affect the user experience of practicability and convenience when applying said detection solution in such applications where the requirements for weighing accuracy is not particularly high, like supermarkets, factories or other environments.

SUMMARY

The technical problem to be solved by the present invention is the low reliability of the weighing process when an object to be weighed extends beyond the bearing surface of the weighing plate.

In order to solve the above technical problem, the invention provides a device for improving weighing reliability. The device comprising a light source arranged on a side surface of a frame of a weighing equipment and used for projecting light beams to the outside of the weighing equipment. The device also comprises an image capture device arranged on the side surface on which the light source is arranged and the image capture device is used for capturing a projection image of the projecting light beams on a projection surface. Further, the device comprises an image processor used for validating whether the projection image is incomplete and thereby determining whether an object to be weighed overlaps the ground surface or the frame of the weighing equipment.

Preferably, the light source arranged on the side surface of the frame of the weighing equipment is inclined downwards at a preset angle with respect to a horizontal direction; and the image capture device captures the projection image of the light source on a support surface of the weighing equipment, such that position of the image capture device is not higher than position of the light source.

Preferably, the projection surface is directly opposite an emission direction of the light source. The light source is inclined upwards at a preset angle with respect to the horizontal direction when arranged on the side surface or on a top surface of the frame of the weighing equipment. The image capture device captures the projection image of the light source on the projection surface, such that the position of the image capture device is not lower than the position of the light source.

Preferably, the frame of the weighing equipment comprises at least four side surfaces; and the light source is arranged on each of the four side surfaces of the frame of the weighing equipment.

Preferably, the device further comprises a vertical bar directly opposite the side surface of the frame of the weighing equipment; and the light source and the image capture device are arranged horizontally close to the ground.

Preferably, the light source is a laser generator.

Preferably, the image capture device is a camera.

The invention also provides a method for improving weighing reliability by using the device, comprising: turning-on the light source when an object to be weighed placed on a weighing platform is detected; capturing a projection image of the light beams on the projection surface by the image capture device; validating whether the projection image is incomplete; and if true, confirming that the object to be weighed overlaps the ground or the frame of the weighing equipment; and if false, confirming that weighing is carried out properly.

Preferably, the light source is a laser generator, and validating whether the projection image is incomplete comprises: validating whether a line segment of light in the projection image is incomplete.

Preferably, the method further comprises signaling a weighing error by an indication device, upon confirming that the object to be weighed overlaps the ground or the frame of the weighing equipment.

The positive effects of the present invention are as follows. The light source projects light beams to the outside of the weighing equipment and the image capture device captures the projection image of the light beams on the projection surface. In case where a part of an object to be weighed extends beyond the bearing surface of the weighing plate and thus overlaps the ground or the table top, the line segment of the light beams or the light beam surface in the projection image will be blocked, causing the projection image to be incomplete. Therefore, by validating the projection image, it can be detected whether the object to be weighed overlaps the ground or the table top. According to the invention, the light source projects light beams to the outside of the weighing equipment instead of forming a projection light path along the side edge of the weighing equipment, so that detection of an object to be weighed extending beyond the bearing surface of the weighing plate can be carried out on a wide range of conditions. For example, the device can be applied successfully in case of irregularly shaped objects for detecting whether the objects overlap a table top of weighing equipment or the ground, thus solving the problems of low applicability and insufficient reliability commonly found in prior art devices.

Some terms referring to particular system components are used throughout the specification and the claims. As can be understood by those skilled in the art, different users may refer to the same component by different names. Components with different names but the same functions do not make any distinction herein and are all within the protection scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic structural diagram of a device for improving weighing reliability according to Embodiment 1 of the invention;

Fig. 2 is a schematic structural diagram of the device for improving weighing reliability according to Embodiment 1, with four side surfaces each provided with a laser generator and a camera;

Fig. 3 is a schematic structural diagram of a device for improving weighing reliability according to Embodiment 2 of the invention;

Fig. 4 is a schematic structural diagram of a device for improving weighing reliability according to Embodiment 3 of the invention; and

Fig. 5 is a flowchart of a method for improving weighing reliability according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

To make the above purpose, features and advantages of the invention more apparent and easier to understand, particular embodiments of the invention are described in detail below with reference to the accompanying drawings.

Embodiment 1: A device for improving weighing reliability according to Embodiment 1 can be provided in a weighing equipment 1 such as a platform scale, a counter scale, an electronic pound scale, an electronic scale and a barcode scale, and is suitable for weighing everyday objects in application scenarios such as factories and supermarkets.

As shown in Fig. 1, a surface of a frame housing of an electronic scale 1 includes a laser generator 11 and a camera 12. The laser generator 11 and the camera 12 can be arranged on other different side surfaces of an electronic scale 1 as required in application, to detect an extending object on any of the other remaining sides of the electronic scale 1, as shown in Fig. 2. The rating and specification of the laser generators 11 should be such that light beams 13 emitted thereby can cover the required detection range. Similarly, the focal length, size, and number of cameras 12 should be such that an image projected by the light beams 13 on a projection surface can be completely captured.

As shown in Fig. 1, the laser generator 11 is strip-shaped and is inclined downwards at a preset angle with respect to a horizontal direction, so that the light beams 13 projected from the laser generator 11 can form a light projection line on a table support surface 2 serving as a projection surface. By increasing the output power of the laser generator 11, a light projection surface can also be formed. The above-mentioned preset inclination angle can be adjusted according to actual use requirements. If it is required to detect whether objects overlap the table support surface 2 in a larger range, the angle can be set to be smaller, so that the light beams 13 emitted by the laser generator 11 are projected farther, and a distance L from the side surface of the electronic scale 1 to the position on the table support surface 2 where the light beams 13 are projected becomes larger. On the contrary, the angle can be set to be larger to reduce the distance L.

The camera 12 is arranged in the same direction, i.e. inclined downward, as that of the laser generator 11to acquire the projection image of the light beams 13 on the projection surface. In order to prevent the shooting range of the camera 12 from being blocked by the laser generator 11, the position of the laser generator 11 is set higher than the position of the camera 12.

When part of the object to be weighed overlaps the ground or the table top of the electronic scale 1, for example, when vegetables are weighed in supermarkets and vegetable leaves overlap the table support surface 2 outside the bearing surface of the electronic scale 1, the vegetable leaves will interfere with the light path of the light beams 13 projected by the laser generator 11, thus blocking the light beams 13 or partially blocking the light beams 13 from being projected on the table support surface 2, and forming an incomplete projection image on the table support surface 2.

An image processor (not shown in the figure) is further included in the electronic scale 1 to identify the projection image captured by the camera 12 and determine whether the projection image is incomplete, that is, whether the light projection line is broken, thereby determining whether the object to be weighed overlaps the frame or the table support surface 2 of the electronic scale 1. It can be identified by edge detection algorithm whether the projection image is incomplete or not. Since the brightness of the light beams 13 are relatively high, the light projection line projected on the table support surface 2 are the places where the gray scale changes most obviously in the projection image, thus becoming an edge. Then, whether the light beams 13 are blocked by the object to be weighed can be determined by detecting whether pixel points forming the edge are continuous, so as to determine whether the object to be weighed overlaps the frame of the electronic scale 1 or the table support surface 2.

In the device for improving weighing reliability of Embodiment 1, the light beams emitted by the laser generator are projected to the outside of the electronic scale, and whether the objects overlap is determined by image identification, thus having a larger detection range. On the one hand, the device can be applied to various types of objects for detecting an extending object and for object overlapping detection. On the other hand, the device can also extend the detection range from the range of the periphery of an electronic scale 1 frame to a supporting platform such as a desktop or the ground on which the electronic scale 1 is placed, thus improving the reliability of weighing results.

Embodiment 2: Compared with the device for improving weighing reliability of Embodiment 1, according to Embodiment 2 as shown in Fig. 3, the laser generator 11 arranged on the side surface of the frame of the electronic scale 1 is inclined upwards at a preset angle with respect to the horizontal direction, and the camera 12 is arranged at a position higher than the position of the laser generator 11. The projection surface of this embodiment is a panel 142 extending obliquely outwards from the frame of the electronic scale 1 through a connector 141. The panel 142 is directly opposite the emitting direction of the laser generator 11 to form a projection surface. The length of the connector 141 may be set to be relatively long in order that the part of the object to be weighed exceeding the bearing surface of the electronic scale 1 does not overlap the connector 141 and the panel 142 as much as possible.

The light beams 13 emitted by the laser generator 11 are projected onto the panel 14. If a part of the object to be weighed exceeds the bearing range of a weighing platform of the electronic scale 1, interferes with the light beams 13 and is projected onto the panel 14 serving as the projection surface, the image processor will identify that the light projection line of the projection image is incomplete.

Since the weighing sensitivity of the central position of the weighing platform of the electronic scale 1 is usually higher than that of the edge of the weighing platform of the electronic scale 1, it is necessary to reposition the object closer to the central position of the weighing platform as possible. The electronic scale 1 issues an alarm in an audible or visible manner through the corresponding indication device, so that an operator can know that the object to be weighed may be partially out of the bearing range of the electronic scale 1 due to not being placed in the center position of the weighing platform of the electronic scale 1. In this way, even if the object to be weighed does not overlap the frame of the electronic scale 1 or the table support surface 2, there may be a subtle error in the weight measurement. By rearranging the object to be weighed to the central position of the weighing platform of the electronic scale 1, weighing results that are relatively more accurate can be obtained.

Those skilled in the art can understand that if the laser generator 11 is arranged on a top surface of the electronic scale 1 and is orientated to incline upwards at a preset angle with respect to the horizontal direction, and the camera is arranged at a position on the side edge or on the top surface of the electronic scale 1 without affecting image acquisition, the above-mentioned detection of an extending object and the technical effect of detecting whether the object to be weighed is placed in the central position of the scale can also be realized, which is also well within the protection scope of the invention.

Embodiment 3: As shown in Fig. 4, a device for improving weighing reliability in this embodiment is applied to an electronic scale 1, and comprises a laser generator 11 and a camera 12 which are arranged on a side surface of a frame housing of the electronic scale 1. The device further comprises a vertical bar 15 which is directly opposite the side surface of the frame of the weighing equipment and serves as a projection surface. If the laser generator 11 and the camera 12 are arranged on the four side surfaces of the electronic scale 1, there will be four vertical bars 15 directly opposite the four side surfaces of the electronic scale 1, respectively, thereby forming a vertical frame surrounding the electronic scale 1.

The laser generator 11 and the camera 12 are arranged close to the ground and are both oriented horizontally. Since the light beam 13 generated by the laser generator 11 also travels in the horizontal direction close to the ground, the height of the vertical bar 15 can be set very low, so long as the projected light segment of the light beams 13 can be displayed.

In Embodiment 3, since the height of the laser generator 11 is set to be horizontally arranged closer to the ground, it is possible to more accurately detect whether the extending part of the object to be weighed actually overlaps the table support surface 2. On the contrary, if the setting position of the laser generator 11 is relatively high, although the extending part of the object to be weighed interferes with the light path of the projection light beams 13 of the laser generator 11, the extending part may not actually overlap the table support surface 2, which will still cause a false positive overlapping.

Ordinarily, for an electronic scale 1 having a smaller width of the side surface of the frame, the possibility of laser generator 11 blocking the shooting range of the camera 12 is more pronounced. By arranging the laser generator 11 horizontally and the camera closer to the ground surface and providing a separate vertical bar as the projection surface of the light beams 13, the afore-mentioned problem that negatively affects the detection range of the laser generator 11 is avoided.

Embodiment 4: A method for improving weighing reliability in Embodiment 4 can be implemented by using the device described in Embodiments 1 to 3 above. As shown in Fig. 5, the method for improving weighing reliability may include the following steps.

In step S101, the laser generator 11 is turned on. When the object to be weighed is placed on the weighing plate of the electronic scale, the weighing sensor of the electronic scale detects the incoming pressure, and the laser generator 11 is turned on to carry out detection of an extending object and overlapping detection.

In step S102, a projection image of the light beams 13 on the projection surface is captured by the camera 12. According to the needs, the camera 12 and the laser generator 11 can be arranged at different positions or in different orientations. Referring to Embodiment 1, if the camera 12 and the laser generator 11 face downwards at a preset angle with respect to the horizontal direction, the projection surface is the support surface of the electronic scale 1. In the present invention, with specific reference to Embodiment 2, if the camera 12 and the laser generator 11 face upwards at a preset angle with respect to the horizontal direction, the projection surface is the separate panel 14. With specific reference to Embodiment 3, if the camera 12 and the laser generator 11 are horizontally arranged closer to the ground, the separate vertical bar serves as the projection surface.

In step S103, it is validated whether the projection image is incomplete. Through the image edge detection algorithm, it can be validated whether the line segment of light in the projection image is broken. If the validation is true, the method proceeds to step S104; otherwise, the method proceeds to step S105 to finish weighing the object as normal.

In step S104, a weighing error is signalled. The indication device may be an audible and/or visual warning device that signals a weighing error to the operator through audible and/or visual signals.

In step S105, it is determined whether the object to be weighed is arranged within a preset time. If the operator picks up the object to be weighed and rearranges it, the electronic scale sensor will detect the pressure change on the weighing plate, which is equivalent to returning to step S101 to perform a new event involving the detection of an extending object. If the operator does not move the object to be weighed within the preset time, it is implied by default that the operator permits a small amount of weighing error, and the weighing operation for the given object is completed further in step S106.

In step S106, the electronic scale finishes weighing the object to be weighed and returns to step S101 to prepare for weighing the next object. In the supermarket weighing environment, after finishing weighing the object to be weighed, the weighing results can be output to a display and also to a portable printer so as to print a bar code tag.

Although the design concept of the invention has been described by way of the particular embodiments above, those skilled in the art will understand that more variations are conceivable based on the teachings of the invention, such as by combining features of the embodiments with each other and/or exchanging functional units between the embodiments. Therefore, they all fall within the protection scope of this application.

Although the invention has been described with reference to the multiple present particular embodiments, a person having ordinary skill in the art is to recognize that the embodiments above are only for explaining the invention and that various equivalent changes or substitutions can be made without departing from the spirit of the invention. Hence, all changes and modifications to the above embodiments within the essential spirit of the invention will fall within the scope of the claims of this application.

Reference signs list

1 weighing equipment; electronic scale

2 table support surface

11 light source; laser generator

12 image capture device; camera

13 light beams

15 vertical bars

141 connector

142 panel

L distance from the side surface of the electronic scale 1

to the position on the table support surface 2 where the

light beams 13 projected becomes larger

Claims

A device for improving weighing reliability, said device comprising a light source (11) arranged on a side surface of a frame of a weighing equipment (1) and used for projecting light beams (13) to outside of the weighing equipment (1) ; an image capture device (12) arranged on the side surface on which the light source (11) is arranged and the image capture device (12) used for capturing a projection image of the projecting light beams on a projection surface; and an image processor used for validating whether the projection image is incomplete, thereby determining whether an object to be weighed overlaps ground surface or the frame of the weighing equipment (1) .
The device of claim 1, wherein the light source (11) arranged on the side surface of the frame of the weighing equipment (1) is inclined downwards at a preset angle with respect to a horizontal direction; and the image capture device (12) captures the projection image of the light source (11) on a support surface (2) of the weighing equipment (1) , such that position of the image capture device (12) is lower than position of the light source (11) .
The device of claim 1, wherein the projection surface is directly opposite an emission direction of the light source (11) ; the light source (11) is inclined upwards at a preset angle with respect to the horizontal direction when arranged on the side surface or on a top surface of the frame of the weighing equipment (1) ; and the image capture device (12) captures the projection image of the light source (11) on the projection surface, such that the position of the image capture device (12) is higher than the position of the light source (11) .
The device of claim 1, wherein the frame of the weighing equipment (1) comprises at least four side surfaces; and the light source (11) is arranged on each of the four side surfaces of the frame of the weighing equipment (1) .
The device of claim 1, wherein the device further comprises a vertical bar (15) directly opposite the side surface of the frame of the weighing equipment (1) ; and the light source (11) and the image capture device (12) are arranged horizontally close to ground surface.
The device of claim 1, wherein the light source (11) is a laser generator.
The device of claim 1, wherein the image capture device (12) is a camera.
A method for improving weighing reliability by using the device of any one of claims 1 to 7, comprising: turning-on the light source (11) when an object to be weighed placed on a weighing platform is detected; capturing a projection image of the light beams (13) on the projection surface by the image capture device (12) ; validating whether the projection image is incomplete; and if true, confirming that the object to be weighed overlaps the ground surface or the frame of the weighing equipment (1) ; and if false, confirming that weighing is carried out properly.
The method of claim 8, wherein the light source (11) is a laser generator, and validating whether the projection image is incomplete comprises: validating whether a line segment of light in the projection image is incomplete.
The method of claim 8, further comprising signalling a weighing error by an indication device, upon confirming that the object to be weighed overlaps the ground surface or the frame of the weighing equipment (1) .