CROSS REFERENCE TO RELATED APPLICATION

This application claims priority and benefits of Chinese Patent Application No. 201310058244.0, filed with State Intellectual Property Office, P. R. C. on February 25, 2013, the entire content of which is incorporated herein by reference.

FIELD

Embodiments of the present disclosure generally relate to a laser fabrication apparatus and a laser fabrication method, more particularly, to a laser processing apparatus and a laser processing method.

BACKGROUND

An SBID (Super-energy Beam Induced Deposition) technology relates to SBID materials, various injection mouldings, a laser activation, a chemical plating, etc. A laser processing apparatus may be designed to implement a prefabrication of a super-energy beam induced and deposited surface for a product (such as a smart mobile phone). The laser processing apparatus usually includes a laser and a robot, in which the laser is configured to fabricate a pattern on a product, the robot is configured to carry the product and to adjust a relative location between the product and the laser according to the pattern, so as to fabricate the desired three-dimensional pattern on a surface of the product. High requirements are presented for the fabrication accuracy of the pattern, such as a shape accuracy and a location accuracy of the three-dimensional pattern, and a gray scale accuracy of pattern lines.

However, the conventional laser processing apparatus cannot ensure the shape accuracy and the location accuracy mentioned above. For example, a deviation of the location accuracy of the conventional laser processing apparatus is usually over ΙΟΟμιη, even more than 200μιη. Thus, the conventional laser processing apparatus is demanded to be improved.

SUMMARY

The present disclosure is presented based on inventors' discoveries and cognitions of following problems: A fabrication accuracy of a laser processing apparatus is usually determined by a repeated positioning (a fabrication location) accuracy of a robot used by the laser processing apparatus. The fabrication accuracy of the laser processing apparatus directly influences an application range and prospect of an SBID technology. Thus, it has been a key point of the SBID technology to improve the fabrication accuracy of the laser processing apparatus, more particularly, a location accuracy of a pattern to be fabricated.

In theory, the repeated positioning accuracy set by a robot manufacturer may meet requirements. However, test conditions for the repeated positioning accuracy are severe, such as a stable ambient temperature, and a light load. In addition, the robot should approach a target fabrication location in a same path and direction; the robot should be warmed up at a low speed for 3 hours and then be warmed up at a high speed for 9 hours before testing; the robot should slow down at a predetermined distance from the target fabrication location, and then approach the target fabrication location at a fairly low speed. However, in practice, it is hard to meet above requirements, such that an actual positioning accuracy is lower than a predetermined positioning accuracy of the robot and the repeated positioning accuracy of the robot cannot meet requirements of the location accuracy of a laser activation pattern. Furthermore, the robot demands to be warmed up for 12 hours, which reduces a production efficiency. Moreover, different robots have different repeated positioning accuracies, which limits a fabrication consistency of the laser processing apparatus and increases a debugging cost, and a maintenance frequency and duration of the laser processing apparatus.

In addition, when the product is fixed on a fixture of the robot each time, an error may occur, which further reduces the location accuracy of the pattern.

Furthermore, an output power of the laser used in a conventional laser processing apparatus is set artificially. After a certain working duration, the output power of the laser may be reduced, which may influence following processes, for example, may decrease a gray level of pattern lines.

Embodiments of the present disclosure seek to solve at least one of the problems existing in the prior art to at least some extent.

According to a first aspect of the present disclosure, a laser processing apparatus is provided, comprising: a robot having a fixture for carrying a product and configured to carry and move the product; a laser configured to fabricate a pattern on the product; a detector configured to detect a current location of the fixture; and a controller connected with the robot, the laser and the detector respectively, and configured to store a standard location of the fixture, to compare the current location of the fixture with the standard location of the fixture to obtain a first comparison result, and to control the robot to move according to the first comparison result so as to adjust the current location of the fixture.

With the laser processing apparatus according to embodiments of the present disclosure, by monitoring the fixture in real time, the repeated positioning accuracy of the robot is controlled in a closed loop, thus correcting the location accuracy of the product in real time so as to improve the fabrication accuracy of the laser activation pattern on the surface of the product.

According to a second aspect of the present disclosure, a laser processing method is provided, comprising: fixing a product on a fixture of a robot; detecting a current location of the fixture; comparing the current location of the fixture with a standard location of the fixture to obtain a first comparison result; controlling the robot to move according to the first comparison result as so to adjust the current location of the fixture; and fabricating a pattern on the product by a laser.

With the laser processing method according to embodiments of the present disclosure, by monitoring the fixture in real time, the repeated positioning accuracy of the robot is controlled in a closed loop, thus correcting the location accuracy of the pattern to be fabricated in real time so as to improve the fabrication accuracy of the laser activation pattern on the surface of the product. Furthermore, the method is simple to implement and greatly broadens the application range and prospect of the SBID technology, which facilities the product quality control and improves the production efficiency.

Additional aspects and advantages of embodiments of present disclosure will be given in part in the following descriptions, become apparent in part from the following descriptions, or be learned from the practice of the embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of embodiments of the present disclosure will become apparent and more readily appreciated from the following descriptions made with reference to the accompanying drawings, in which:

Fig. 1 is a schematic perspective view of a laser processing apparatus according to an embodiment of the present disclosure;

Fig. 2 is a partial perspective view of the laser processing apparatus shown in Fig. 1; and Fig. 3 is a flow chart of a laser processing method according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the present disclosure. The same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions. The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present disclosure. The embodiments shall not be construed to limit the present disclosure.

In the specification, unless specified or limited otherwise, relative terms such as "central",

"longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "upper", "horizontal", "vertical", "above", "below", "up", "top", "bottom" ,"inner", "outer", "clockwise", "anticlockwise" as well as derivative thereof (e.g., "horizontally", "downwardly", "upwardly", etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the present disclosure be constructed or operated in a particular orientation.

In addition, terms such as "first" and "second" are used herein for purposes of description and are not intended to indicate or imply relative importance or significance. Thus, features limited by "first" and "second" are intended to indicate or imply including one or more than one these features. In the description of the present disclosure, "a plurality of relates to two or more than two.

In the description of the present disclosure, unless specified or limited otherwise, it should be noted that, terms "mounted," "connected" "coupled" and "fastened" may be understood broadly, such as permanent connection or detachable connection, electronic connection or mechanical connection, direct connection or indirect connection via intermediary, inner communication or interreaction between two elements. These having ordinary skills in the art should understand the specific meanings in the present disclosure according to specific situations.

In the description of the present disclosure, a structure in which a first feature is "on" a second feature may include an embodiment in which the first feature directly contacts the second feature, and may also include an embodiment in which an additional feature is formed between the first feature and the second feature so that the first feature does not directly contact the second feature, unless otherwise specified. Furthermore, a first feature "on," "above," or "on top of a second feature may include an embodiment in which the first feature is right "on," "above," or "on top of the second feature, and may also include an embodiment in which the first feature is not right "on," "above," or "on top of the second feature, or just means that the first feature has a sea level elevation larger than the sea level elevation of the second feature. While first feature "beneath," "below," or "on bottom of a second feature may include an embodiment in which the first feature is right "beneath," "below," or "on bottom of the second feature, and may also include an embodiment in which the first feature is not right "beneath," "below," or "on bottom of the second feature, or just means that the first feature has a sea level elevation smaller than the sea level elevation of the second feature.

As we all known, a conventional laser processing apparatus primarily includes a laser, a robot and an electrical control system. During an operation, a corresponding fixture is disposed on a clamping flange of the robot by operators according to a three-dimensional pattern of a product, and then the product is disposed on the fixture. The robot moves the product to a certain location under the laser according to a predetermined program, and then the laser fabricates a laser activation pattern in a certain range on a surface of the product with a certain output power. When the laser activation pattern within the range is completed, the robot moves to place a next fabrication range on the surface of the product under the laser. Such a process is repeated until the desired three-dimensional pattern is formed on the surface of the product. In practice, there are generally two robots operating in turns. A location accuracy of the pattern is primarily determined by a repeated positioning accuracy of the robot, and the overall process is controlled in an open loop without any closed loop feedback correcting function. Furthermore, an output power of the laser is set artificially, which also lacks the closed loop feedback correcting function. Therefore, the conventional laser processing apparatus has following defects.

(1) Test conditions for the repeated positioning accuracy are severe, such as a stable ambient temperature, and a light load. In addition, the robot should approach a target fabrication location in a same path and direction; the robot should be warmed up at a low speed for 3 hours and then be warmed up at a high speed for 9 hours before testing; the robot should slow down at a predetermined distance from the target fabrication location, and then approach the target fabrication location at a fairly low speed. However, in practice, it is hard to meet above requirements, such that an actual positioning accuracy is lower than a predetermined positioning accuracy of the robot and the repeated positioning accuracy of the robot cannot meet requirements of the location accuracy of a laser activation pattern. Furthermore, the robot demands to be warmed up for 12 hours, which reduces a production efficiency. Moreover, different robots have different repeated positioning accuracies, which limits a fabrication consistency of the laser processing apparatus and increases a debugging cost, and a maintenance frequency and duration of the laser processing apparatus.

(2) When the product is fixed on a fixture of the robot each time, an error may occur, which further reduces the location accuracy of the pattern.

(3) An output power of the laser used in a conventional laser processing apparatus is set artificially. After a certain working duration, the output power of the laser may be degraded, which may influence following processes, for example, may decrease a gray scale of pattern lines.

These defects result in the fact that a deviation of the location accuracy of the pattern fabricated by the conventional laser processing apparatus is usually over ΙΟΟμιη, even more than 200μιη.

With reference to Fig. 1 and Fig. 2, a laser processing apparatus according to an embodiment of the present disclosure will be described in the following. Fig. 1 is a schematic perspective view of the laser processing apparatus according to the embodiment of the present disclosure, and Fig. 2 is a partial perspective view of the laser processing apparatus shown in Fig. 1.

As shown in Fig. 1 and Fig. 2, the laser processing apparatus includes a robot 1, a laser 2, a detector 3 and a controller (not shown).

Specifically, the laser processing apparatus according to embodiments of the present disclosure further includes an apparatus support 4, a sheet metal housing 5 having an operating window 7, and a robot support 6. In this embodiment of the present disclosure, the robot 1 (i.e., a manipulator) includes two six-axis robots (i.e., a six-axis robot a on a left side and a six-axis robot b on a right side). It should be understood that the number of the robots is not limited to two, and a plurality of six-axis robots may be applied in practice.

As shown in Fig. 2, each robot 1 has a fixture (not shown) for carrying a product (such as a cell phone shell). For example, the fixture is disposed on a clamping flange 8 of each robot 1, and the product is disposed on the fixture, such that each robot 1 can carry and move the product.

The laser 2 is configured to fabricate a laser activation pattern on the product. The detector 3 is configured to detect a current location of the fixture. The controller is connected with the robot 1, the laser 2 and the detector 3 respectively, and is configured to store a standard location of the fixture. The controller is further configured to compare the current location of the fixture detected by the detector 3 with the standard location of the fixture to obtain a first comparison result, and to control the robot 1 to move according to the first comparison result so as to adjust the current location of the fixture, such that the current location of the fixture infinitely approaches the standard location of the fixture, even is fully coincident with the standard location of the fixture.

In some embodiments of the present disclosure, the detector 3 is further configured to detect a current fabrication location of the product; and the controller is further configured to store a standard fabrication location of the product, to compare the current fabrication location of the product with the standard fabrication location of the product to obtain a second comparison result, and to control the robot 1 to move according to the second comparison result so as to adjust the current fabrication location of the product, such that the current fabrication location of the product infinitely approaches the standard fabrication location of the product, even is fully coincident with the standard fabrication location of the product, thus improving the fabrication accuracy of the product.

In some embodiments of the present disclosure, the detector 3 is further configured to detect a gray level of the pattern; and the controller is further configured to store a standard pattern gray level, to compare the gray level of the pattern with the standard pattern gray level to obtain a third comparison result, and to adjust an output power of the laser 2 according to the third comparison result, such that the gray level of the pattern infinitely approaches the standard pattern gray level, even is fully coincident with the standard pattern gray level.

In an embodiment of the present disclosure, as shown in Fig. 2, the detector 3 comprises: a CCD (Charge Coupled Device) camera 10 and a displacement sensor 20. The CCD camera 10 is configured to image a marker on the fixture so as to obtain a coordinate of the marker in an X-Y plane. Specifically, the coordinate of the marker in the X-Y plane comprises: a coordinate of the marker on an X axis, a coordinate of the marker on a Y axis and a rotation angle U in the X-Y plane. The displacement sensor 20 is configured to detect a coordinate of the fixture on a Z axis. Specifically, the displacement sensor 20 may be a laser displacement sensor. Accordingly, the current location of the fixture may be represented by {X, Y, U, Z} .

In some embodiments of the present disclosure, the fixture is disposed on the clamping flange a marker (such as a block marker) is formed on the fixture. The six-axis robots 1 are configured to move the product from the operating window 7 to a focal point just under the laser 2. The CCD camera 10 is located in a moving path of the robots 1 and close to a laser activation location. The displacement sensor 20 is disposed nearby the CCD camera 10 and is configured to detect a height of the clamping flange 8 with respect to the laser 2 when the CCD camera images the marker.

With the laser processing apparatus according to embodiments of the present disclosure, by monitoring the fixture in real time via the detector 3, the repeated positioning accuracy of the robots 1 is controlled in a closed loop, thus correcting the location accuracy of the product in real time so as to improve the fabrication accuracy of the laser activation pattern on the surface of the product. In addition, by controlling the output power of the laser 2 in a closed loop, a reduction of the output power of the laser 2 can be corrected in real time so as to ensure the laser activation effect. Thus, not only is the shape accuracy of the laser activation pattern ensured, but also a deviation of the location accuracy may be reduced from an original range of over ΙΟΟμιη to a range of below 40μιη (i.e., ±20μιη). Moreover, by correcting the reduction of the output power of the laser 2 in real time, negative influences on following processes can be avoided, thus improving a quality of the product.

Those having ordinary skill in the related art may understand that, the standard location of the fixture stored in the controller may be set when the laser processing apparatus is debugged. After the standard location of the fixture is determined, the product is disposed on the fixture to set the standard fabrication location of the product. Then, a standard product is placed in the standard fabrication location, and the detector 3 samples a gray level of a pattern of the standard product as the standard pattern gray level and the standard pattern gray level is stored in the controller.

Specifically, during debugging of the laser processing apparatus, the standard location of the fixture, the standard fabrication location and the standard pattern gray level are set. Firstly, a height of a focal plane of the laser 2 is obtained, and then the fixture is moved onto the focal plane by the robots 1. Further, a height of the fixture is kept constant, and then the marker on the fixture is moved just under the CCD camera 10 by the robots 1 and then imaged by the CCD camera 10. An image of the marker is analysed and a current coordinate of the robots 1 is fed back to the controller. The coordinate of the marker on the X axis, the coordinate of the marker on the Y axis and the rotation angle U in the X-Y plane are calculated by the controller according to the current coordinate of the robots 1 and a location and a direction of the marker in the image of the marker, and the coordinates {X, Y, U} are stored in the controller as an X-Y plane template. Meanwhile, the height of the fixture with respect to the laser 2 is detected by the displacement sensor 20 and is fed back to the controller. The coordinate of the fixture on the Z axis is calculated by the controller according to the current coordinate of the robots 1, and is stored in the controller as a Z axis template. After the templates have been stored, the fixture is moved just under the laser 2 by the robots 1, and a location and an attitude of the product are adjusted to ensure that an expected part of the product is irradiated by the laser 2. After adjusting the location and the attitude of the product, the location of the product is stored as the standard fabrication location. In other words, according to the coordinates X, Y, U and the coordinate of the fixture on the Z axis (i.e., {X, Y, U, Z}), the standard location of the fixture can be determined and stored, and a location of the product located on the fixture which is at the standard location of the fixture is the standard fabrication location of the product. Then, the laser activated standard product is disposed on the fixture, and is moved just under the CCD camera 10 by the robots 1. The standard product is imaged by the CCD camera 10 and a reticule location, a reticule width and a reticule gray level of the laser activated standard product are extracted from an image of the standard product and are fed back to the controller, in which the reticule location, the reticule width and the reticule gray level are stored as a detecting template, i.e., the standard pattern gray level.

As shown in Fig. 1, in practice, the product is placed on the fixture through the operating window 7 of the sheet metal housing 5 by an operator. The marker of the fixture is moved just under the CCD camera 10 by the six-axis robots 1 and then imaged by the CCD camera 10 to obtain a current image of the marker, and the current image of the marker is fed back to the controller. The controller compares a current image of the marker with the X-Y plane template to obtain deviations in coordinates X, Y, U. Meanwhile, the current height of the fixture is detected by the displacement sensor 20 and is fed back to the controller. The controller compares the current height of the fixture with the Z axis template to obtain a deviation in the coordinate Z. Then, the robots 1 are controlled by the controller to correspondingly shift according to the above deviations in coordinates X, Y, U, Z, so as to ensure that the current fabrication location is coincident with the standard fabrication location. Subsequently, the laser 2 fabricates the laser activation pattern on the product. When the pattern in one fabrication range is completed, the robots 1 move the product and place a next fabrication range of the product just under the laser 2 by rotating, stretching and retracting and so on for fabrication. Above process is repeated until the three-dimensional pattern is completed.

After the laser activation is completed, the product is moved just under the CCD camera 10 by the robots 1, and the data of the reticule width, the reticule location and the reticule gray level of the laser activated product are collected and fed back to the controller. The controller compares the data with the detecting template, outputs a detecting report about a width and location deviation and stores a gray level deviation. For example, after the data is detected each 10 times, values of the reticule gray level are averaged. When an average reticule gray level is more than the standard pattern gray level, then a corresponding reduction of the output power of the laser 2 is calculated by the controller and is transmitted to a control unit in the laser 2 to gain the output power so as to compensate for the reduction of the output power of the laser 2, thus ensuring the laser activation effect.

After the laser activation is completed, the laser activated product is further processed by chemical plating. It should be noted that, only a laser activated part of the product can be processed by the chemical plating. In other words, a laser activation accuracy of the pattern on the product directly determines a chemical plating accuracy of the pattern, and finally determines the accuracy and the quality of the product. Therefore, with the laser processing apparatus according to embodiments of the present disclosure, the shape accuracy and the location accuracy of the pattern on the product are improved, and the laser activated part of the product is further processed by the chemical plating, such that the accuracy and the quality of the product are ensured.

In the embodiment of the present disclosure, the six-axis robot a on the left side and the six-axis robot b on the right side share the same CCD camera 10, which works in turns for the six-axis robot a and the six-axis robot b. The controller serves as a server and is connected with the detector 3 to exchange data. The robot (more specifically, a controller for the robot) serves as a client to access the server. When an imaging is needed, the robot sends a request to the server, then the server responds to the request and transmits the data from the detector 3 to the corresponding client, such that the six-axis robot a and the six-axis robot b share the same CCD camera 10.

In conclusion, with the laser processing apparatus according to embodiments of the present disclosure, not only is the shape accuracy of the pattern on the product ensured, but also a deviation of the location accuracy may be reduced from the original range of over ΙΟΟμιη to the range of below 40μιη (i.e., ±20μιη). By detecting the pattern gray level via the CCD camera, the reduction of the output power of the laser can be corrected online and in real time. Thus, the application range of the SBID technology is greatly broadened. In addition, the location, the size and the gray level accuracy of the pattern may be processed by data operations as input data for quality control (such as a data analysis tool of 6 Sigma quality control), which facilities the quality control for the product and improves the production efficiency.

A laser processing method according to embodiments of the present disclosure will be described in the following. Fig. 3 is a flow chart of the laser processing method according to an embodiment of the present disclosure. As shown in Fig. 3, the laser processing method includes following steps.

At step SI, a product is fixed on a fixture of a robot. For example, the product may be a mobile phone shell.

At step S2, a current location of the fixture is detected.

At step S3, the current location of the fixture is compared with a standard location of the fixture to obtain a first comparison result.

At step S4, the robot is controlled to move according to the first comparison result so as to adjust the current location of the fixture.

At step S5, a pattern is fabricated on the product by a laser.

As described above, the standard location of the fixture is pre-stored in a controller of the laser processing apparatus. Specifically, a marker disposed on the fixture is imaged by a CCD camera to obtain a coordinate of the marker in an X-Y plane. Specifically, the coordinates of the marker in the X-Y plane comprises: a coordinate of the marker on an X axis, a coordinate of the marker on a Y axis and a rotation angle U in the X-Y plane. A coordinate of the fixture on a Z axis is detected by a displacement sensor. Accordingly, the current location of the fixture may be represented by {X, Y, U, Z} . Therefore, according to the coordinate {X, Y, U, Z}, the standard location of the fixture can be obtained and be stored in the controller.

In one embodiment, the laser processing method further includes following steps: detecting a current fabrication location of the product; comparing the current fabrication location of the product with a standard fabrication location of the product to obtain a second comparison result; and controlling the robot to move according to the second comparison result so as to adjust the current fabrication location of the product.

A location of the product located on the fixture which is at the standard location of the fixture is the standard fabrication location of the product. After the laser activation is completed, the laser activated product is processed by a chemical plating. It should be noted that, only a laser activated part of the product can be processed by the chemical plating. In other words, a laser activation accuracy of the pattern on the product directly determines a chemical plating accuracy of the pattern, and finally determines the accuracy and the quality of the product.

With the laser processing method according to embodiments of the present disclosure, not only is the shape accuracy of the pattern on the product ensured, but also a deviation of the location accuracy may be reduced from the original range of over ΙΟΟμιη to the range of below 40μιη (i.e., ±20μιη). Therefore, with the laser processing method according to embodiments of the present disclosure, the shape accuracy and the location accuracy of the pattern on the product are improved, and the laser activated part of the product is further processed by the chemical plating, such that the accuracy and the quality of the product are ensured.

In one embodiment, the laser processing method further includes following steps: detecting a gray level of the pattern; comparing the detected gray level of the pattern with a standard pattern gray level to obtain a third comparison result; and adjusting an output power of the laser according to the third comparison result.

Specifically, the laser activated standard product is disposed on the fixture, and is moved just under the CCD camera 10 by the robots 1. The standard product is imaged by the CCD camera 10 and a reticule location, a reticule width and a reticule gray level of the laser activated standard product are extracted from an image of the standard product and are fed back to the controller, in which the reticule location, the reticule width and the reticule gray level are stored as a detecting template, i.e., the standard pattern gray level.

By detecting the pattern gray level via the CCD camera, the reduction of the output power of the laser can be corrected online and in real time.

In one embodiment, the robot is a six-axis robot.

In one embodiment, the number of the robots is two.

With the laser processing method according to embodiments of the present disclosure, by monitoring the fixture in real time, the repeated positioning accuracy of the robot is controlled in a closed loop, thus correcting the location accuracy of the pattern to be fabricated in real time so as to improve the fabrication accuracy of the laser activation pattern on the surface of the product. Moreover, the reduction of the output power of the laser can be corrected online and in real time, thus ensuring the laser activation effect. Furthermore, the method is simple to implement and greatly broadens the application range and prospect of the SBID technology, which facilities the product quality control and improves the production efficiency.

In the description, any procedure or method described in the flow charts or described in any other way herein may be understood to comprise one or more modules, portions or parts for storing executable codes that realize particular logic functions or procedures. Moreover, advantageous embodiments of the present disclosure comprises other implementations in which the order of execution is different from that which is depicted or discussed, including executing functions in a substantially simultaneous manner or in an opposite order according to the related functions. This should be understood by those skilled in the art to which embodiments of the present disclosure belong.

Reference throughout this specification to "an embodiment," "some embodiments," "one embodiment", "another example," "an example," "a specific example," or "some examples," means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as "in some embodiments," "in one embodiment", "in an embodiment", "in another example," "in an example," "in a specific example," or "in some examples," in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present disclosure, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present disclosure.