阅读说明：本技术 一种精密电连接器的智能盲插装配单元 (Intelligent blind-mate assembly unit of precise electric connector ) 是由 端赣来 冯展鹰 张柳 王仁彻 李明 杜一民 谢协国 于 2020-04-16 设计创作，主要内容包括：本发明涉及一种精密电连接器的智能盲插装配单元,所述盲插装配单元包括电连接器上料装置、装配机构、控制单元和工作台装置；所述电连接器上料装置、所述装配机构和所述控制单元分别设置在装配工位上；所述电连接器上料装置用于电连接器的自动上料；所述装配机构用于实现所述电连接器的抓取、定位及装配动作；所述控制单元用于控制所述电连接器上料装置、所述装配机构和所述工作台装置各自动作；所述工作台装置用于待装件的逐一定位装夹,并将所述待装件送至所述装配工位装配所述电连接器。本发明能够实现盲插电连接器的智能化、高精度、高可靠装配,保证产品精度与电性能指标。(The invention relates to an intelligent blind-mate assembly unit of a precision electric connector, which comprises an electric connector feeding device, an assembly mechanism, a control unit and a workbench device, wherein the electric connector feeding device is connected with the assembly mechanism; the electric connector feeding device, the assembling mechanism and the control unit are respectively arranged on an assembling station; the electric connector feeding device is used for automatically feeding the electric connector; the assembling mechanism is used for realizing the grabbing, positioning and assembling actions of the electric connector; the control unit is used for controlling the actions of the electric connector feeding device, the assembling mechanism and the workbench device; the workbench device is used for positioning and clamping the parts to be assembled one by one, and conveying the parts to be assembled to the assembling station to assemble the electric connector. The invention can realize intelligent, high-precision and high-reliability assembly of the blind-mate electric connector and ensure the product precision and the electrical performance index.)

1. An intelligent blind-mate assembly unit of a precision electric connector is characterized by comprising an electric connector feeding device (3), an assembly mechanism (4), a control unit (7) and a workbench device (9); the electric connector feeding device (3), the assembling mechanism (4) and the control unit (7) are respectively arranged on an assembling station;

the electric connector feeding device (3) is used for automatically feeding the electric connector; the assembling mechanism (4) is used for realizing the grabbing, positioning and assembling actions of the electric connector; the control unit (7) is used for controlling the electric connector feeding device (3), the assembling mechanism (4) and the workbench device (9) to respectively act; the workbench device (9) is used for positioning and clamping the parts to be assembled one by one, and conveying the parts to be assembled to the assembling station to assemble the electric connector.

2. The smart blind mate assembly unit of precision electrical connectors according to claim 1, characterized in that the assembly mechanism (4) comprises a force and displacement sensing assembly (45), a tip clamp (46), a tip vision system (47); the force and displacement sensing assembly (45), the tip clamp (46) and the tip vision system (47) are all mounted at the end of the assembly mechanism (4);

the force and displacement sensing assembly (45) is used for acquiring real-time parameters of assembly dynamics and transmitting the parameters to the control unit (7); the end clamp (46) is used for grabbing the electric connector conveyed by the electric connector feeding device (3); the end vision system (47) is used for positioning the pre-installation position of the electric connector on the to-be-installed part and the electric connector in real time and transmitting positioning information to the control unit (7); the assembling mechanism (4) is driven by the control unit (7) to adjust the electric connector in real time, so that the electric connector is self-adaptively assembled on the part to be assembled.

3. The intelligent blind-mate assembly unit of a precision electrical connector according to claim 2, wherein the assembly mechanism (4) further comprises a base (41), a six-axis robot (42), a cylinder gripper (43) and an assembly panel (44); the six-axis manipulator (42) is mounted on the base (41) and can rotate around the base (41) in six axial directions; one end of the cylinder clamping jaw (43) is connected with the end part of the six-axis manipulator (42), and the other end of the cylinder clamping jaw (43) is fixed with the assembling panel (44); the force and displacement sensing assembly (45), the tip clamp (46), and the tip vision system (47) are mounted on the mounting panel (44), respectively.

4. The intelligent blind-mate assembly unit of a precision electrical connector according to claim 2 or 3, wherein the end clamp (46) comprises a seat (461), a spool (462), a precision strain spring (463), a guide rod (464), a flexible clamping jaw (465) and a mounting plate; the support (461) is installed at the bottom end of the assembling mechanism (4), one end of the valve core (462) is installed on the support (461), and the other end of the valve core penetrates through the installing plate to be connected with the flexible clamping jaw (465); the upper end and the lower end of the precision strain spring (463) are respectively connected with the support (461) and the mounting plate and are sleeved on the valve core (462); the guide rod (464) is sleeved on the flexible clamping jaw (465) and is fixed on the mounting plate; the flexible clamping jaw (465) can be opened after extending out of the guide rod (464) under the action of the valve core (462).

5. Intelligent blind-mate assembly unit of precision electrical connectors according to claim 4, characterized in that the bottom end of the flexible clamping jaw (465) consists of a plurality of jaws made of memory titanium alloy.

6. The intelligent blind-mate assembly unit of a precision electrical connector according to claim 4 or 5, characterized in that the inner side of the flexible clamping jaw (465) is provided with a layer of wear-resistant soft non-metallic material.

7. The intelligent blind-mate assembly unit of a precision electrical connector according to claim 1, characterized in that all surfaces in the electrical connector loading device (3) that are in contact with the electrical connector have a non-metallic fabric layer.

8. The intelligent blind-mate assembly unit of a precision electrical connector according to claim 1, further comprising a vision detection system (8), wherein the vision system detection system (8) is installed on the assembly station, located above the workbench device (9), and configured to detect information on accuracy and initial positioning of the to-be-assembled part entering the assembly station, transmit detection parameters to the control unit (7), and detect the assembled workpiece in real time.

9. The intelligent blind-mate assembly unit of the precision electrical connector according to claim 1, further comprising a workpiece feeding device (1) and a workpiece loading device (2), wherein the workpiece feeding device (1) is located at one side of the control unit (7) and is used for taking the to-be-assembled part out of a product standard tray and sending the to-be-assembled part to a specified position; the workpiece feeding device (2) is located above the side of the control unit (7) and used for taking the pieces to be assembled out of the specified position and conveying the pieces to be assembled one by one onto the workbench device (9).

10. The intelligent blind-mate assembly unit of the precision electrical connector according to claim 1, further comprising a workpiece blanking device (5) and a workpiece discharging device (6), wherein the workpiece blanking device (5) clamps the assembled workpiece and sends the workpiece to the workpiece discharging device (6) and the workpiece is sent out through the workpiece discharging device (6).

Technical Field

The invention relates to a blind-mate assembly unit of an electric connector, in particular to an intelligent blind-mate assembly unit of a precise electric connector, and belongs to the field of automatic assembly.

Background

With the development of science and technology, the interconnection mode of modern electrical equipment is gradually upgraded from traditional cable connection to blind-mate electrical connector connection, and the blind-mate electrical connector is small in size, light in weight, capable of greatly saving space and reducing product weight. The current common electrical connector interconnection scheme consists of three parts, two sockets and a double-female adapter through which electrical connection is realized, and the common connectors of the interconnection technology comprise MBX type, BMP type and SMP type.

In two types of blind-mate electrical connectors shown in fig. 1 and 2, the quality of the surface coating and the assembly uniformity of the electrical connectors transmitting radio frequency signals are important factors affecting the electrical performance of products. The current blind-mate electric connector is mainly assembled manually, and during assembly, the risk of damage to a coating on the surface of the electric connector caused by scraping, sweat stain and the like is high; the quality of the assembly of the electrical connector is different for different persons and at different times. Through investigation, some connector manufacturers and users can customize assembly mechanisms according to specific connector models, the application range is small, and popularization and application cannot be achieved basically.

For example, patent No. CN 103702535 a discloses a positioning device for a blind-mate connector of a chassis, which can ensure the assembly accuracy of the blind-mate connector, but cannot realize automatic assembly, has a small application range and poor flexibility, and cannot ensure the consistency of each assembly.

Disclosure of Invention

In order to solve the problem of poor assembling quality and consistency of the blind-mate electric connector, the invention provides the intelligent blind-mate assembling unit of the precise electric connector, which can realize intelligent, high-precision and high-reliability assembling of the blind-mate electric connector and ensure the precision and electrical performance indexes of a product.

An intelligent blind-mate assembly unit of a precision electric connector is characterized in that the blind-mate assembly unit comprises an electric connector feeding device, an assembly mechanism, a control unit and a workbench device; the electric connector feeding device, the assembling mechanism and the control unit are respectively arranged on an assembling station;

the electric connector feeding device is used for automatically feeding the electric connector; the assembling mechanism is used for realizing the grabbing, positioning and assembling actions of the electric connector; the control unit is used for controlling the actions of the electric connector feeding device, the assembling mechanism and the workbench device; the workbench device is used for positioning and clamping the parts to be assembled one by one, and conveying the parts to be assembled to the assembling station to assemble the electric connector.

Further, the assembly mechanism comprises a force and displacement sensing assembly, a tip clamp, a tip vision system; the force and displacement sensing assembly, the tip clamp and the tip vision system are all mounted at the end of the assembly mechanism;

the force and displacement sensing assembly is used for acquiring real-time parameters of assembly dynamics and transmitting the parameters to the control unit; the tail end clamp is used for grabbing the electric connector conveyed by the electric connector feeding device; the terminal vision system is used for positioning the pre-installation position of the electric connector on the to-be-installed part and the electric connector in real time and transmitting positioning information to the control unit; the assembling mechanism is used for driving the electric connector to be adjusted in real time through the control unit, so that the electric connector is self-adaptively assembled on the part to be assembled.

Furthermore, the assembly mechanism also comprises a base, a six-axis manipulator, a cylinder clamping jaw and an assembly panel; the six-axis manipulator is arranged on the base and can rotate around the base in six axial directions; one end of the cylinder clamping jaw is connected with the end part of the six-axis manipulator, and the other end of the cylinder clamping jaw is fixed with the assembling panel; the force and displacement sensing assembly, the end fixture and the end vision system are mounted on the mounting panel, respectively.

Furthermore, the tail end clamp comprises a support, a valve core, a precision strain spring, a guide rod, a flexible clamping jaw and a mounting plate; the support is arranged at the bottom end of the assembling mechanism, one end of the valve core is arranged on the support, and the other end of the valve core penetrates through the mounting plate to be connected with the flexible clamping jaw; the upper end and the lower end of the precision strain spring are respectively connected with the support and the mounting plate and sleeved on the valve core; the guide rod is sleeved on the flexible clamping jaw and fixed on the mounting plate; the flexible clamping jaw can be opened after extending out of the guide rod under the action of the valve core.

Further, the bottom end of the flexible clamping jaw consists of a plurality of jaws made of memory titanium alloy.

Furthermore, the inner side of the flexible clamping jaw is provided with a wear-resistant soft non-metallic material layer.

Further, all the surfaces in the feeding device of the electric connector, which are in contact with the electric connector, are provided with the non-metal fabric layer.

Furthermore, the blind plugging assembly unit further comprises a vision detection system, wherein the vision system detection system is installed on the assembly station and located above the workbench device, and is used for detecting the accuracy and initial positioning information of the to-be-assembled part entering the assembly station, transmitting detection parameters to the control unit, and simultaneously detecting the assembled workpiece in real time.

Furthermore, the blind-mate assembly unit further comprises a workpiece feeding device and a workpiece loading device, wherein the workpiece feeding device is positioned on one side of the control unit and is used for taking the to-be-assembled part out of the standard product tray and sending the to-be-assembled part to a specified position; the workpiece feeding device is positioned above the side of the control unit and used for taking the pieces to be assembled out of the specified position and conveying the pieces to be assembled to the workbench device one by one.

Furthermore, the blind-mate assembly unit further comprises a workpiece discharging device and a workpiece discharging device, wherein the workpiece discharging device clamps the assembled workpiece and conveys the assembled workpiece to the workpiece discharging device, and the workpiece is discharged through the workpiece discharging device.

The invention has the beneficial effects that:

the invention can realize high-quality and automatic assembly of the electric connector on the part to be assembled and can improve the consistency of the assembly quality. The invention realizes automatic material taking and automatic assembly through the automatic feeding device of the to-be-assembled part and the electric connector and the assembly mechanism, and also utilizes the visual detection system to determine the position of the to-be-assembled part and the detection of missing assembly and neglected assembly of the assembled workpiece so as to improve the assembly qualification rate. The invention also realizes the multi-angle flexible assembly of the electric connector by a six-axis manipulator, a flexible clamping jaw and the like of the assembly mechanism, and ensures 100 percent acquisition of dynamic parameters of the assembly by utilizing a force and displacement sensing assembly and a terminal vision system so as to realize the self-adaptive assembly of the electric connector, ensure the consistency and traceability of the assembly quality of products and ensure the assembly qualification rate of more than 99 percent; and the invention also avoids the damage to the surface of the electric connector by the non-metallic material layer. In addition, the invention can also adopt a series of components, can be suitable for high-precision automatic assembly of various similar products and realizes high-degree flexible assembly.

Drawings

FIG. 1 is a first schematic structural diagram of a blind-mate assembly unit in the prior art;

FIG. 2 is a schematic structural diagram of a blind-mate assembly unit in the prior art;

FIG. 3 is a schematic diagram of an intelligent blind-mate assembly unit of the precision electrical connector of the present invention;

FIG. 4 is a schematic structural view of an assembly mechanism according to the present invention;

fig. 5 is a schematic structural view of the end clamp of the present invention.

Wherein: 1-workpiece feeding device, 2-workpiece feeding device, 3-electric connector feeding device, 4-assembly mechanism, 41-base, 42-six-axis manipulator, 43-cylinder clamping jaw, 44-assembly panel, 45-force and displacement sensor assembly, 46-end clamp, 461-support, 462-valve core, 463-precision strain spring, 464-guide rod, 465-flexible clamping jaw, 47-end vision system, 5-workpiece blanking device, 6-workpiece discharging device, 7-control unit, 8-vision detection system and 9-workbench device.

Detailed Description

In order to make those skilled in the art better understand the technical solutions of the present application, the present invention will be further described in detail below with reference to the accompanying drawings and examples.

The terms of orientation such as up, down, left, right, front, and rear in the present specification are established based on the positional relationship shown in the drawings. The corresponding positional relationship may also vary depending on the drawings, and therefore, should not be construed as limiting the scope of protection.

In the present invention, the terms "mounted," "connected," "fixed," and the like are to be understood in a broad sense, and for example, may be fixedly connected, detachably connected, integrally connected, mechanically connected, electrically connected or capable of communicating with each other, directly connected, indirectly connected through an intermediate medium, or communicated between two components, or interacting between two components. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

This embodiment has recorded an intelligent blind-mate assembly cell of accurate electric connector, and this blind-mate assembly cell can realize the automation of work piece installation electric connector to guarantee installation quality and installation uniformity.

As shown in fig. 3, the blind-mate assembling unit includes a workpiece feeding device 1, a workpiece feeding device 2, an electrical connector feeding device 3, an assembling mechanism 4, a workpiece discharging device 5, a workpiece discharging device 6, a control unit 7, a visual detection system 8 and a workbench device 9, wherein the electrical connector feeding device 3, the assembling mechanism 4, the control unit 7 and the visual detection system 8 are installed on an assembling station, the workpiece feeding device 1 sends a to-be-assembled part to the workbench device 9 through the workpiece feeding device 2 for positioning and clamping, after the workbench device 9 sends the to-be-assembled part to the assembling station one by one, the assembling mechanism 4 picks up the electrical connector conveyed by the electrical connector feeding device 3 and installs the electrical connector at a corresponding position of the to-be-assembled part under the control of the control unit 7, the visual detection system 8 is used for detecting the conditions of missing and wrong assembly of the to-be-assembled part on the workbench device 9 and carrying out primary positioning detection on the to-be-, and real-time detection is carried out in the assembling process, and after the assembling is finished, the workpiece discharging device 5 sends the workpiece to the workpiece discharging device 6 for discharging.

In this embodiment, the workpiece feeding device 1 and the workpiece discharging device 6 are respectively disposed on the left and right sides of the control unit 7, and the workpiece feeding device 2 and the workpiece discharging device 5 are respectively disposed above the left and right sides of the control unit 7. The workpiece feeding device 1 is used for taking out a to-be-mounted workpiece from a product standard tray and sending the to-be-mounted workpiece to a specified position (such as a specified position of an inlet of the workpiece feeding device 2). The workpiece feeding device 2 is a conveying device, and is used for taking out the workpieces to be assembled from the designated position, conveying the workpieces to be assembled one by one to the workbench device 9, and conveying the workpieces to be assembled to the assembly station through the workbench device 9. After the electric connector is assembled on the assembling station, the workpiece discharging device 5 clamps the assembled workpiece and sends the workpiece to the workpiece discharging device 6. The workpiece discharge device 6 is used for discharging the assembled workpieces from the assembly station. In this embodiment, the workpiece feeding device 1 and the workpiece discharging device 6 both adopt a servo module driving form, and the workpiece feeding device 2 and the workpiece discharging device 5 have substantially the same structure and both adopt a form that a motor and an air cylinder drive a guide rail.

The control unit 7 is located in the middle of the blind-mate assembling unit and on one side of an assembling station, the control unit 7 is connected with the workpiece feeding device 1, the workpiece feeding device 2, the electric connector feeding device 3, the assembling mechanism 4, the workpiece discharging device 5, the workpiece discharging device 6, the vision detection system 8, the workbench device 9 and a control center (namely a master control system of a plurality of devices in a workshop) respectively, the actions of all the components in the blind-mate assembling unit are controlled in real time through an MODBUS standard communication protocol, the interconnection between the blind-mate assembling unit and the control center is realized through an RJ-45 Ethernet protocol (an RS232 protocol can be converted into an RJ-45 protocol), and therefore the control unit 7 realizes integration between all the components in the blind-mate assembling unit and the control center through an embedded system.

The workbench device 9 comprises a positioning clamping assembly and a conveying assembly, and is used for positioning, clamping and conveying the parts to be packaged. In this embodiment, the vision system detection system 8 is located above the workbench device 9, and is configured to detect accuracy and initial positioning information of a workpiece to be assembled entering the assembly station, transmit detection parameters to the control unit 7, and perform real-time detection on the assembled workpiece. In this embodiment, can set up the two-dimensional code in advance on treating the dress piece, the accuracy that supplies is detected through the two-dimensional code that the piece was treated in the scanning to vision detection system 8, carries out the location detection through vision detection to and the detection that the back work piece lacks dress, neglected loading.

The electric connector feeding device 3 is arranged on one side of the assembling station and used for automatically feeding the electric connectors. The electric connector feeding device 3 of the embodiment can comprise a connector discharging mechanism, a feeding device and a storage bin, wherein the electric connector is stored in the storage bin, the connector discharging mechanism and the connector discharging mechanism are respectively arranged at the inlet and outlet ends of the feeding device, the connector discharging mechanism is used for placing the electric connectors in the storage bin one by one on the feeding device and sending the electric connectors to the connector discharging mechanism, and the assembling mechanism 4 is used for grabbing the electric connectors in the connector discharging mechanism one by one and assembling the electric connectors to a part to be assembled. All surfaces in the electric connector feeding device 3, which are in contact with the electric connector, are provided with non-metal fabric layers so as to reduce the abrasion of the electric connector.

The assembling mechanism 4 is installed on an assembling station and used for realizing grabbing, positioning and assembling actions of the electric connector. As shown in fig. 4, the assembly mechanism 4 includes a base 41, a six-axis robot 42, cylinder jaws 43, an assembly panel 44, a force and displacement sensing assembly 45, an end clamp 46, and an end vision system 47. The six-axis manipulator 42 is installed on the base 41, one end of the cylinder clamping jaw 43 is connected with the end part of the six-axis manipulator 42, the six-axis manipulator 42 can rotate around the base 41 in six axial directions, the assembly panel 44 is fixedly installed at the other end of the cylinder clamping jaw 43, and the force and displacement sensing assembly 45, the tail end clamp 46 and the tail end vision system 47 are respectively installed on the assembly panel 44. When the electric connector is assembled by a part to be assembled, the force and displacement sensing assembly 45 is used for acquiring real-time parameters of assembly dynamics, transmitting the parameters to the control unit 7, comparing the parameters with standard parameter values stored in a database in the control unit 7, and driving the assembly mechanism 4 to adjust in real time according to the comparison result by the control unit 7, so that the self-adaptive assembly of the electric connector is realized. The end clamps 46 are used for gripping the electrical connectors transported by the electrical connector feeding device 3. The end vision system 47 is used to position the electrical connector on the ready-to-mount device in real time and to position the electrical connector, while the control unit 7 directs the end gripper 46 to precisely remove and mount the electrical connector from the electrical connector loading device 3 onto the ready-to-mount device.

The end clamp 46 used in this embodiment is shown in fig. 5 and includes a seat 461, a spool 462, a precision strain spring 463, a guide rod 464, a flexible jaw 465 and a mounting plate. The support 461 is mounted on the cross beam of the assembly panel 44, one end of the valve core 462 is mounted on the support 461, the other end passes through the mounting plate to be connected with the flexible clamping jaw 465, and the support 461 and the mounting plate are arranged in parallel. The upper end and the lower end of the precision strain spring 463 are respectively connected with the support 461 and the mounting plate and are sleeved on the valve core 462, when the valve core 462 stretches, the precision strain spring 463 stretches, the force and displacement sensing assembly 45 collects the stretching amount of the precision strain spring 463 and transmits the stretching amount to the control unit 7, and the control unit 7 can calculate the stress of the precision strain spring 463 according to the stretching amount. The guide rod 464 suit is on flexible clamping jaw 465, and the top is fixed on the mounting panel, and guide rod 464 plays the effect of drawing in spacingly to flexible clamping jaw 465. The bottom end of the flexible clamping jaw 465 is composed of a plurality of claws made of memory titanium alloy, and the bottom end can be opened after the flexible clamping jaw 465 extends out of the guide rod 464 under the action of the valve core 462 for gripping the electric connector. The inside of the flexible jaw 465 is provided with a layer of wear resistant flexible non-metallic material to prevent scratching of the electrical connector. The bottom of guide bar 464 has the boss in this embodiment, and the design of boss not only can strengthen the limiting displacement in guide bar 464 bottom, still can be when assembling electric connector, supports treating dress surface, plays and prevents that guide bar 464 from stretching into the limiting displacement in treating the dress piece along with flexible clamping jaw 465 synchronous.

When the end clamp 46 clamps the electrical connector, the assembly mechanism 4 drives the valve core 462 to extend outwards, the valve core 462 pushes the flexible clamping jaw 465 to extend out from the guide rod 464, and the flexible clamping jaw 465 is driven by the six-axis manipulator 42 to open towards the electrical connector, and at the moment, the precision strain spring 463 is stretched in a tensile mode. After the flexible claw 465 grips the electrical connector, the fitting mechanism 4 gradually reduces the driving force, and the flexible claw 465 contracts and grips the electrical connector into the guide rod 464 by the restoring force of the precision strain spring 463.

When the electric connector is assembled in the part to be assembled, the assembling mechanism 4 drives the end clamp 46 to press the electric connector into a pre-assembling position of the part to be assembled through the six-axis manipulator 42, at the moment, the flexible clamping jaw 465 is pressed to extend out of the guide rod 464, the precision strain spring 463 is pressed, the support 461 and the precision strain spring 463 are communicated with the force and displacement sensing device 45, the force and displacement sensing device 45 detects assembling dynamic parameters (such as the expansion amount of the precision strain spring 463, the pressure on the electric connector and the like) in real time, posture adjustment is carried out within an allowable range of a database, when the electric connector is subjected to preset pressure, the flexible clamping jaw 465 loosens the electric connector, the assembling mechanism 4 accurately assembles the electric connector to the position, the six-axis manipulator 42 drives the assembling mechanism 4 to leave a workpiece, and the flexible clamping jaw 465 contracts into the guide rod 464 to reset under the reset action of the precision strain spring.

In addition, the end clamp 46 of the present embodiment can be manufactured in a variety of sizes, and when different electrical connectors are mounted, the end clamp 46 or the guide lever 463 and the flexible clamping jaw 464 can be replaced according to the specification of the electrical connectors. In addition, the specification and the size of other components in the embodiment can be replaced by a suitable specification product according to the to-be-assembled component and the electric connector, so that the application range of the scheme of the embodiment is further enlarged.

While the principles of the invention have been described in detail in connection with the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing embodiments are merely illustrative of exemplary implementations of the invention and are not limiting of the scope of the invention. The details of the embodiments are not to be interpreted as limiting the scope of the invention, and any obvious changes, such as equivalent alterations, simple substitutions and the like, based on the technical solution of the invention, can be interpreted without departing from the spirit and scope of the invention.