A circuit, method, and mobile device for detecting the grounding connection status of the mobile device housing.

Abstract

This invention discloses a circuit, method, and mobile device for detecting the grounding connection status of a mobile device casing, belonging to the field of electronic device testing technology. To address the problems of low efficiency, high cost, and difficulty in automation of existing detection methods, this invention provides two core circuits: a series resistor network scheme that connects multiple grounding connection points to the nodes of a resistor string, determining an open circuit at any point by measuring whether the voltage at the end jumps from near zero to the test voltage; and a digital logic scheme that connects to a microcontroller's GPIO via pull-up resistors, directly reading the level status of each point for independent judgment and location. The corresponding detection method includes steps of applying a test signal, reading the response electrical signal, and determining the status based on signal characteristics. This invention transforms the physical state of multiple mechanical connections into changes in a single or set of electrical signals, achieving rapid, automated, and low-cost online detection, and can assist in fault location, significantly improving production quality inspection efficiency and product reliability.

Description

Technical Field

[0001] This invention relates to the field of electronic device testing technology, specifically to a mobile device housing grounding connection status detection circuit, method, and mobile device. Background Technology

[0002] In the manufacturing and assembly of mobile devices (such as smartphones and tablets), to ensure good electromagnetic compatibility (EMC) performance, stable radio frequency (RF) signal quality, and effective electrostatic discharge (ESD) protection, the ground plane on the printed circuit board (PCB) is typically reliably electrically connected to the metal frame or device housing through multiple mechanical connection points. These connection points are often achieved using methods such as screw fastening, metal spring contact, or conductive foam crimping. The reliability of these connections directly affects the shielding effect of the internal circuitry and the radiation performance of the antenna.

[0003] Currently, in the quality inspection stage after mobile device assembly, there is a lack of an efficient, low-cost method suitable for comprehensive testing on automated production lines to verify whether all the aforementioned grounding connection points are reliably connected. Existing technologies mainly rely on the following methods:

[0004] 1. Manual visual inspection: Operators rely on experience to observe the appearance of connection points (such as whether screws are installed) to make judgments. This method is inefficient and cannot confirm the electrical integrity of the connection, posing a high risk of missed detections and misjudgments.

[0005] 2. Final Functional Testing: A comprehensive RF performance test (such as Total Radiated Power (TRP) and Total Isotropic Sensitivity (TIS)) is performed on the entire device in an anechoic chamber. Failure to meet performance standards can indirectly suggest a possible grounding problem. However, this method requires expensive specialized testing equipment and facilities, has a long testing cycle, and is not suitable for rapid full inspection of every device on a production line. Furthermore, this method cannot precisely pinpoint which one or more grounding connection points are faulty, hindering rapid rework.

[0006] 3. General-purpose multimeter point testing: Using a multimeter to measure the continuity of each grounding connection point one by one. However, in mobile devices with highly compact internal structures and where test points may be obstructed by other components, physical contact with the test points is difficult to operate, resulting in extremely low testing efficiency and making it difficult to automate the testing process.

[0007] In summary, existing technologies for detecting the grounding connection status of mobile device casings generally suffer from low detection efficiency, high labor or equipment costs, difficulty in achieving fully automated inspection, and inability to quickly locate fault points. Therefore, there is an urgent need for a technical solution that can be integrated into the equipment and rapidly, automatically, and accurately determine the continuity of all grounding connections on the production line. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention discloses a mobile device housing grounding connection status detection circuit, method, and mobile device to solve the aforementioned problems.

[0009] This invention is achieved through the following technical solution:

[0010] A mobile device housing grounding connection status detection circuit, the core concept of which is to map the physical on / off state of multiple mechanical grounding connection points into one or a set of easily measurable and analyzable electrical signal characteristic changes through a specific circuit topology.

[0011] The specific technical solutions are as follows, depending on the implementation method:

[0012] Option 1: Series Resistor Network Detection Circuit

[0013] The detection circuit includes: a detection voltage input terminal (Vtest), a voltage measurement terminal (Vmeasure), three or more precision resistors (R1, R2, ..., Rn) connected in series, and a number of corresponding ground connection points (P1, P2, ..., Pn).

[0014] The precision resistors are connected in series between Vtest and Vmeasure to form a resistor network. Each ground connection point under test is not directly shorted to the PCB ground, but is connected between each pair of adjacent precision resistors (e.g., between R1 and R2, R2 and R3, ..., between Rn and Vmeasure). Vtest is used to receive a known, stable DC reference voltage.

[0015] Its working principle is as follows: When all grounding connection points are reliably connected to the casing ground, the series resistor network forms a complete ground loop through the casing ground. At this time, the voltage value of Vmeasure is a calculable, near-low level reference voltage (V_ref). When any one or more grounding connection points are broken, the ground loop of the resistor network after that break point is cut off. According to the voltage divider principle, the voltage of Vmeasure will be pulled up to a value close to Vtest. By monitoring whether the voltage of Vmeasure experiences a significant jump, the connection status can be determined.

[0016] Option 2: Digital Logic Detection Circuit

[0017] The detection circuit includes a logic control unit (such as a microcontroller (MCU), a central processing unit (CPU), or a dedicated logic chip) and a pull-up resistor network.

[0018] Each ground connection point under test (P1, P2, ..., Pn) is connected to the logic power supply (Vcc) through an independent pull-up resistor (Rp1, Rp2, ..., Rpn). Simultaneously, the PCB side of each connection point is connected to the PCB signal ground (GND). Each connection point's node is also connected to an independent general-purpose input / output (GPIO) pin of the logic control unit.

[0019] Its working principle is as follows: When a ground connection point is reliably connected, the voltage level at that point is clamped to a low level by the casing ground, and the corresponding GPIO pin reads a low-level signal. When a ground connection point is disconnected, the voltage level at that point is pulled up to a high level (Vcc) through a pull-up resistor, and the corresponding GPIO pin reads a high-level signal. The logic control unit reads the status of all relevant GPIO pins through polling or interruption. Only when all pins are low is the connection considered normal; if any pin is high, a connection point is considered disconnected, and the specific failure point can be identified.

[0020] Accordingly, the present invention also provides a detection method corresponding to the above circuit, which mainly includes the following steps: applying a detection signal, acquiring an output electrical signal characterizing the connection state, and judging the state based on the parameter characteristics of the output electrical signal (such as voltage amplitude and digital logic level combination).

[0021] In other aspects, the present invention also provides a mobile device, including a housing, a PCB disposed within the housing, and at least two grounding connection points for connecting the PCB grounding layer to the housing. The mobile device also includes the aforementioned mobile device housing grounding connection status detection circuit.

[0022] The beneficial effects of this invention are as follows:

[0023] This invention offers highly efficient detection capabilities and is suitable for automation: by measuring a single voltage point or reading a set of digital signals, the status judgment of all designed connection points can be completed at once, with extremely short processing time (milliseconds), making it perfectly compatible with high-speed automated production line processes.

[0024] This invention is inexpensive and easy to implement: the core circuit consists only of common low-cost components such as conventional surface-mount resistors and general-purpose logic chips, which increases the overall material cost of the device almost without increasing it. It does not require expensive external specialized testing equipment.

[0025] This invention features high integration and saves space: the detection circuit can be directly laid out in the blank area of ​​the main PCB of the device without changing the existing mechanical structure such as the shell and the middle frame, and does not occupy additional physical space.

[0026] This invention provides objective and highly reliable judgments: based on electrical signals, the detection results are digitized, objective, and accurate, completely avoiding subjective misjudgments and missed detections caused by manual visual inspection.

[0027] This invention is highly scalable: the number of detection points can be expanded by simply increasing the number of series resistors; the digital logic scheme can also be easily expanded by increasing GPIO resources, making it easy to adapt to the requirements of different product models.

[0028] This invention has preliminary fault location capability: especially in digital logic schemes, it can directly identify which specific connection point has failed, providing clear guidance for rapid rework. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the series resistor network circuit according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the digital logic detection circuit according to an embodiment of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] This invention provides a circuit and method for detecting the grounding connection status of a mobile device casing, aiming to solve the problems of low efficiency, high cost, difficulty in automation, and inability to locate fault points in the detection of indirect grounding connection points between the PCB and casing of mobile devices in the prior art. The core concept of this invention is to map the physical connectivity status of multiple dispersed mechanical grounding connection points to the change of a centralized, easily automated electrical parameter (such as a voltage value or a set of digital logic levels) through an innovative circuit topology, thereby achieving fast, accurate, and low-cost status determination.

[0034] The technical solution of the present invention will be described in detail below through several specific embodiments. These embodiments can be implemented individually or used in combination according to actual needs.

[0035] Example 1: Detection circuit and implementation method based on series resistor network and voltage criterion

[0036] Reference Figure 1 The diagram illustrates a series resistor network circuit, showcasing a specific implementation of a detection circuit for use in a smartphone. The detection circuit is integrated onto the main printed circuit board of the phone.

[0037] The detection circuit is characterized in that it includes:

[0038] A sense voltage input (Vtest) is used to receive a stable DC reference voltage.

[0039] A voltage measurement terminal (Vmeasure) serves as a signal output point for voltage measurement.

[0040] A resistor network consisting of three precision resistors R1, R2, and R3 connected in series is provided. This resistor network is connected between the detection voltage input terminal and the voltage measurement terminal.

[0041] Three grounding connection points P1, P2, and P3 are to be tested. Connection point P1 is connected to the series connection node of resistors R1 and R2, connection point P2 is connected to the series connection node of resistors R2 and R3, and connection point P3 is connected to the node between resistor R3 and the voltage measurement terminal. Each grounding connection point P1, P2, and P3 is electrically connected to the metal frame or casing of the smartphone via a mechanical connection (screws in this embodiment), thereby achieving electrical connection between the PCB ground layer and the casing ground.

[0042] Specific implementation parameters and scenario 1 (final inspection on the production line):

[0043] In the mobile phone assembly line, as part of the final testing process, surface-mount resistors with a resistance of 10.0kΩ and an accuracy of ±1% are selected as R1, R2, and R3. The detection voltage input terminal is connected to a stable 1.8V system power supply on the mobile phone motherboard (e.g., from the power management chip). The voltage measurement terminal is designed as an exposed test pad on the PCB.

[0044] During testing, the two probes on the test fixture of the automated test equipment (ATE) automatically position and contact the Vtest and Vmeasure pads on the PCB. The ATE performs the following steps:

[0045] 1. Apply a DC test voltage of 1.8V to the Vtest pad through the first probe.

[0046] 2. Measure the real-time voltage value V_meas on the Vmeasure pad using the second probe.

[0047] 3. Compare V_meas with a preset reference voltage threshold V_th (e.g., set to 0.1V).

[0048] 4. Make a judgment: If V_meas≤V_th, then all screw connection points (P1, P2, P3) are reliably connected, and the test result is "PASS"; if V_meas>V_th (in this scenario, any screw not tightened will cause V_meas to jump to about 1.8V), then at least one grounding connection point is found to be faulty, the test result is "FAIL", and an audible and visual alarm is immediately triggered or the signal is sent to the automatic repair station.

[0049] Specific implementation parameters and scenario two (multi-connection point expansion and internal self-test):

[0050] The circuit structure of this invention has inherent scalability. For tablet computers with more grounding screws (e.g., 5), the detection circuit can be expanded to include 5 precision resistors (R1~R5) connected in series and 5 corresponding connection points (P1~P5), with the connection method as above. At this time, the theoretical value of the reference voltage V_ref (the voltage when all points are connected normally) of the voltage measurement terminal Vmeasure is still close to 0V. When any connection point is disconnected, the Vmeasure voltage is pulled up to close to the Vtest voltage. This circuit can also be used for internal debugging during the device development phase. Engineers can connect Vtest to an adjustable power supply and Vmeasure to a multimeter, and visually observe the voltage change during manual tightening / loosening of the screws to verify the reliability of the design.

[0051] Example 2: Detection circuit and implementation method based on digital logic and level criteria

[0052] Reference Figure 2 This paper presents a digital logic detection circuit, demonstrating an implementation of a detection circuit for use in smartwatches or Bluetooth headsets. The circuit is integrated on the device's motherboard.

[0053] The detection circuit is characterized in that it includes:

[0054] A microcontroller that acts as a logic control unit has a detection program embedded inside.

[0055] A pull-up resistor network consists of three independent pull-up resistors Rp1, Rp2, and Rp3.

[0056] Three grounding connection points to be tested: P1, P2, and P3.

[0057] The specific connection is as follows: one end of each pull-up resistor (Rp1, Rp2, Rp3) is connected to the logic power supply Vcc (e.g., 3.3V). The other end of each pull-up resistor is connected to an independent general-purpose input / output pin (GPIO1, GPIO2, GPIO3) of the logic control unit, and also to a ground connection point under test (P1, P2, P3). The PCB side of each ground connection point under test (P1, P2, P3) is connected to the signal ground of the PCB. The connection points are electrically connected to the metal housing or internal shielding of the device through conductive foam or metal springs.

[0058] Specific implementation parameters and scenario three (equipment power-on self-test and fault recording):

[0059] In the mass-produced version of the smartwatch, a low-cost ARM Cortex-M0 core MCU with multiple GPIO ports is selected as the logic control unit. Pull-up resistors Rp1~Rp3 are all 100kΩ, connected to a 3.3V I / O power supply. During each power-on initialization phase, the MCU automatically executes the following detection process embedded in Flash:

[0060] 1. Configure GPIO1, GPIO2, and GPIO3 as digital input modes.

[0061] 2. Read the voltage levels of these three pins at once.

[0062] 3. Execute the judgment logic: If (GPIO1==low level&&GPIO2==low level&&GPIO3==low level), then it is determined that all grounding connection points are normal, and the program continues to execute the normal power-on process.

[0063] 4. If the above conditions are not met (i.e., any pin is high), then a grounding failure is determined. The MCU may perform at least one of the following operations:

[0064] Fault status codes (e.g., recording which GPIOs are high) are written to a specific log area in non-volatile memory (such as EEPROM) for analysis during after-sales maintenance.

[0065] Display concise error codes on the device screen, or control LED indicators to flash specific fault modes.

[0066] In extreme cases, if poor grounding may affect critical safety functions (such as RF power), the RF module may be prevented from starting or entering a restricted safety mode.

[0067] Specific implementation parameters and scenario four (dedicated test station and precise positioning):

[0068] In the dedicated functional testing station of the Bluetooth headset production line, an external dedicated test MCU or FPGA can be used as the logic control unit. The ground connection point of each headset (possibly connected via a miniature spring) is led to the corresponding probe on the test fixture. At the start of the test, the external control unit simultaneously reads the status of all GPIOs. Since each connection point corresponds independently to one GPIO, when a test fails, the test system can immediately and accurately display on the screen whether it is an "abnormal left channel shield connection point" or a "abnormal motherboard ground screw point," greatly improving the positioning efficiency and repair accuracy for rework workers.

[0069] Explanation of the combination and generality between embodiments:

[0070] It should be noted that the two technical solutions provided in this invention (analog voltage criterion and digital logic criterion) are not mutually exclusive; they share the same inventive concept. Those skilled in the art will understand that:

[0071] The "precision resistor" can be a conventional surface mount resistor, thin film resistor, etc.

[0072] The "logic control unit" is not limited to MCU, but can be the system main processor (AP / CPU), a dedicated logic chip (such as CPLD), or even a simple circuit composed of discrete logic gates.

[0073] The "detection voltage" can originate from any stable power network already present within the device (such as core voltage or I / O voltage), or it can be provided by an external testing device.

[0074] The implementation methods of the "grounding connection point to be tested" include, but are not limited to, screw fastening, metal spring contact, conductive foam pressing, conductive adhesive bonding, and any structure designed to achieve electrical connection between the PCB and the housing.

[0075] The term "mobile device" includes, but is not limited to, any electronic device with a metal casing or internal shielding structure that requires reliable grounding, such as smartphones, tablets, laptops, smartwatches, Bluetooth headsets, portable medical devices, and industrial handheld terminals.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mobile device housing grounding connection status detection circuit, characterized in that, include: The system consists of a voltage input terminal Vtest, a voltage measurement terminal Vmeasure, and a resistor network consisting of at least three precision resistors (R1, R2, ..., Rn) connected in series. The resistor network is connected between the detection voltage input terminal Vtest and the voltage measurement terminal Vmeasure; At least three ground connection points to be tested (P1, P2, ..., Pn) are respectively connected between every two adjacent precision resistors in the resistor network and between the last precision resistor and the voltage measurement terminal Vmeasure. Each of the grounding connection points to be tested (P1, P2, ..., Pn) is used to electrically connect the ground layer of the printed circuit board (PCB) of the mobile device to the housing or frame, where n ≥ 3.

2. The mobile device housing grounding connection status detection circuit according to claim 1, characterized in that, The precision resistors (R1, R2, ..., Rn) have the same resistance value, where n ≥ 3.

3. The mobile device housing grounding connection status detection circuit according to claim 1, characterized in that, The detection voltage input terminal Vtest is used to receive a stable DC reference voltage from the internal power system of the mobile device.

4. The mobile device housing grounding connection status detection circuit according to claim 1, characterized in that, It also includes a comparison and judgment unit, which compares the actual voltage value of the voltage measurement terminal Vmeasure with a preset reference voltage threshold, and outputs a judgment signal indicating whether all grounding connection points are connected normally or have an open circuit based on the comparison result.

5. A mobile device housing grounding connection status detection circuit, characterized in that, include: Logic control unit and pull-up resistor network; The pull-up resistor network includes at least two pull-up resistors (Rp1, Rp2, ..., Rpn), with one end of each pull-up resistor connected to the logic power supply Vcc. At least two ground connection points to be tested (P1, P2, ..., Pn) are provided. One end of each ground connection point is connected to the PCB signal ground GND of the mobile device, and the other end, together with the other end of a corresponding pull-up resistor, is connected to a general-purpose input / output GPIO pin of the logic control unit, where n≥3.

6. The mobile device housing grounding connection status detection circuit according to claim 5, characterized in that, The logic control unit is a microcontroller (MCU), a central processing unit (CPU), or a dedicated logic chip.

7. A method for detecting the grounding connection status of a mobile device housing, based on the mobile device housing grounding connection status detection circuit according to any one of claims 1 to 4, characterized in that, Includes the following steps: A stable test voltage is applied to the detection voltage input terminal Vtest; Measure the actual voltage value at the voltage measuring terminal Vmeasure; Determine the continuity status of all grounding connection points under test based on the actual voltage value.

8. The detection method according to claim 7, characterized in that, The determination step specifically includes: The actual voltage value is compared with a preset reference voltage value; If the actual voltage value is less than or equal to the reference voltage value, then all grounding connection points under test are determined to be connected normally. If the actual voltage value is greater than the reference voltage value, then at least one grounding connection point under test is determined to be disconnected.

9. A method for detecting the grounding connection status of a mobile device housing, based on the mobile device housing grounding connection status detection circuit according to claim 5 or 6, characterized in that, Includes the following steps: The logic control unit reads the level state of each of the GPIO pins; Determine the continuity of all grounding connections under test based on the voltage levels of each GPIO pin.

10. A mobile device, comprising a housing, a PCB disposed within the housing, and at least two grounding connection points for connecting the PCB ground plane to the housing, characterized in that, The mobile device further includes a mobile device housing ground connection status detection circuit as claimed in any one of claims 1 to 4 or any one of claims 5 to 6.

Images