Printed circuit board impedance detection apparatus

Abstract

A printed circuit board impedance detection device includes a controller, a voltage detector, a detection resistor, a pre-charge switch and a switching circuit. The controller controls the pre-charge switch to make the parasitic capacitance of the switching circuit be charged by a pre-charge voltage supplied by a pre-charge voltage supply device for a pre-charge time. The controller detects and obtains a detection voltage of the detection resistor by the voltage detector. The controller judges the detection voltage to judge the relationship between a resistance value of a detection impedance of a printed circuit board and a preset resistance value.

Description

Technical Field

[0001] This invention relates to an impedance detection device, and more particularly to a printed circuit board impedance detection device. Background Technology

[0002] Please refer to Figure 1 This is a simplified circuit block diagram of a printed circuit board impedance detection device based on related technologies. After the printed circuit board is manufactured, it contains many lines. To check whether these lines have been arranged and manufactured according to the design, it is necessary to detect whether the impedance between these lines is abnormal (e.g., detecting whether there are connections that should not be connected, or connections that should be connected but are not). At this time, a circuit is used... Figure 1 The circuit principle (i.e., using Ohm's law) is used to calculate the impedance of the two lines currently being tested (i.e., Figure 1 The resistance value of the detection impedance 204 is used to determine if there is any abnormality. Figure 1 Among them, the detection voltage supply device 30 provides detection voltage 302, and the detection resistor 106 has detection voltage 114 (i.e., cross voltage).

[0003] Among them, the above Figure 1 The circuit principle is as follows: the resistance value of the detection impedance 204 = the voltage across the detection impedance 204 / current = (detection voltage 302 - detection voltage 114) / current = (detection voltage 302 - detection voltage 114) / (detection voltage 114 / resistance value of detection resistor 106); where the values ​​of the detection voltage 302 and the detection resistor 106 are both known, and a voltage detector (not shown) is used. Figure 1 The detection voltage 114 can be detected, and the resistance value of the detection impedance 204 can be calculated to determine whether the resistance value of the detection impedance 204 is abnormal.

[0004] Please refer to Figure 2 This is a circuit block diagram of an example of a printed circuit board impedance detection device 50 in the related technology. Figure 2 The components shown are Figure 1 For the sake of simplicity, the same components shown will not be described again here. As mentioned above, after the printed circuit board 20 is manufactured, because many printed circuit board lines 202 of the printed circuit board 20 need to be tested, methods such as... Figure 2 The plurality of upper switches 116 and the plurality of lower switches 118 shown are switched for detection; the dashed arrows indicate the direction of current. Please refer to... Figure 3 This is a circuit block diagram of another example of a printed circuit board impedance detection device 50 in the related technology. Figure 3 The components shown are Figure 2For the sake of simplicity, the same components shown will not be described again here.

[0005] As described above, after the upper switches 116 and the lower switches 118 have completed their switching, the entire circuit should immediately reach a steady state, thereby utilizing the aforementioned... Figure 1 The circuit principle is to detect whether the resistance value of the detection impedance 204 is abnormal; however, in reality, after the upper switches 116 and the lower switches 118 have finished switching, the entire circuit still has to wait for a period of time (e.g., 1.2 milliseconds) to reach a steady state, so the overall detection time will be very long.

[0006] Please refer to the following: Figure 2 and Figure 3 These switches (especially the lower switches 118) are manufactured using a high-voltage process to withstand high voltages (i.e., high detection voltages 302, such as 10 volts to 300 volts). This results in a parasitic capacitance 112, which is estimated to be approximately 5 nF (details to follow). Because the detection impedance 204 has a very high resistance (e.g., above 1 MΩ), the parasitic capacitance 112 requires a long charging time to reach a steady state (only in a steady state can the aforementioned...). Figure 1 The circuit principle is used to calculate the resistance value of the detection impedance 204, which is the reason why the overall detection time (i.e., whether there is a situation where it should be connected but is connected, or a situation where it should be connected but is not connected) is very long.

[0007] The following three experiments can be conducted to estimate the value of the parasitic capacitance 112: The first experiment uses only the upper switch 116 but not the lower switch 118. After the upper switch 116 changes from non-conducting to conducting, the voltage waveform of the detected voltage 114 shows that it takes only 1.5 microseconds to reach a steady state. The second experiment uses both the upper switch 116 and the lower switch 118, but the lower switch 118 remains conducting. After the upper switch 116 changes from non-conducting to conducting, the voltage waveform of the detected voltage 114 shows that it takes 1.2 milliseconds to reach a steady state. The third experiment uses only the upper switch 116 but not the lower switch 118, and a 5nF capacitor is connected in parallel with the detected resistor 106. After the upper switch 116 changes from non-conducting to conducting, the voltage waveform of the detected voltage 114 shows that it takes 1.2 milliseconds to reach a steady state. Therefore, based on the above three experiments, it can be estimated that the parasitic capacitance 112 is approximately 5nF. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a printed circuit board impedance detection device.

[0009] To achieve the above-mentioned objectives of the present invention, the printed circuit board impedance detection device of the present invention is applied to a printed circuit board and a pre-charge voltage supply device. The printed circuit board includes a plurality of printed circuit board lines forming a detection impedance. The printed circuit board impedance detection device includes: a controller; a voltage detector electrically connected to the controller; a detection resistor electrically connected to the voltage detector; a pre-charge switch electrically connected to the controller, the voltage detector, and the detection resistor; and a switching circuit electrically connected to the controller, the voltage detector, the detection resistor, and the pre-charge switch, wherein the switching circuit has a plurality of parasitic capacitances; the controller is configured to control the pre-charge switch to charge the parasitic capacitances by a pre-charge voltage provided by the pre-charge voltage supply device for a pre-charge time; the controller is configured to detect and obtain a detection voltage of the detection resistor by the voltage detector; the controller is configured to determine the relationship between a resistance value of the detection impedance and a preset resistance value by judging the detection voltage.

[0010] The advantage of this invention is that it can quickly determine whether there are any abnormalities in the manufactured printed circuit board.

[0011] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit this invention. Attached Figure Description

[0012] Figure 1 This is a simplified circuit block diagram of a printed circuit board impedance detection device for related technologies.

[0013] Figure 2 This is a circuit block diagram of an example of a printed circuit board impedance detection device for related technologies.

[0014] Figure 3 This is a circuit block diagram of another example of a printed circuit board impedance detection device for related technologies.

[0015] Figure 4 This is a simplified circuit block diagram of the printed circuit board impedance detection device of the present invention.

[0016] Figure 5 This is an experimental voltage waveform diagram of the detection voltage of the present invention.

[0017] Figure 6 This is another experimental voltage waveform diagram of the detection voltage of the present invention.

[0018] Figure 7This is a flowchart illustrating the method for operating the printed circuit board impedance detection device of the present invention.

[0019] Figure 8 This is a circuit block diagram of a specific embodiment of the printed circuit board impedance detection device of the present invention.

[0020] Figure 9 This is a circuit block diagram of another specific embodiment of the printed circuit board impedance detection device of the present invention.

[0021] In the attached figures, the following labels are used:

[0022] 10: Printed Circuit Board Impedance Detection Device

[0023] 20: Printed Circuit Board

[0024] 30: Voltage supply detection device

[0025] 40: Pre-charge voltage supply device

[0026] 50: Printed Circuit Board Impedance Detection Device of Related Technologies

[0027] 102: Controller

[0028] 104: Voltage Detector

[0029] 106: Detection resistor

[0030] 108: Pre-charge switch

[0031] 110: Switching circuit

[0032] 112: Parasitic capacitance

[0033] 114: Detect Voltage

[0034] 116: Upper switch

[0035] 118: Lower switch

[0036] 202: Printed Circuit Board Circuit

[0037] 204: Detection Impedance

[0038] 302: Detection Voltage

[0039] 402: Pre-charge voltage

[0040] S02: Steps

[0041] S04: Steps

[0042] S06: Steps

[0043] S08: Steps

[0044] S10: Steps

[0045] S12: Steps

[0046] S14: Steps

[0047] S16: Steps

[0048] t1: First time point

[0049] t2: Second time point Detailed Implementation

[0050] This disclosure provides numerous specific details to give a thorough understanding of particular embodiments of the invention; however, those skilled in the art will recognize that the invention can be practiced without one or more of these specific details; in other instances, well-known details have not been shown or described to avoid obscuring the key technical features of the invention. The technical content and detailed description of the invention are explained below in conjunction with the accompanying drawings:

[0051] Please refer to the following: Figure 2 and Figure 3 As mentioned earlier, these switches (especially the lower switches 118) are manufactured using a high-voltage process to withstand high voltages (i.e., high detection voltages 302, such as 10 volts to 300 volts), thus creating parasitic capacitances 112. Because the detection impedance 204 has a very high resistance (e.g., above 1 MΩ), these parasitic capacitances 112 require a long charging time to reach a steady state (only in a steady state can the aforementioned...). Figure 1 The circuit principle is used to calculate the resistance value of the detection impedance 204, which is the reason why the overall detection time (i.e., whether there is a situation where it should be connected but is connected, or a situation where it should be connected but is not connected) is very long.

[0052] To address the shortcomings of the aforementioned related technologies, the solutions and principles of this invention are detailed below: Please refer to... Figure 4 This is a simplified circuit block diagram of the printed circuit board impedance detection device of the present invention; firstly, the present invention utilizes Figure 4 The following experiment was conducted:

[0053] In this invention, the detection impedance 204 is set to 100 MΩ, the detection voltage 302 is set to 10 volts, the detection resistor 106 is set to 10 KΩ, the parasitic capacitance 112 is set to 5 nF, and the pre-charge voltage 402 is set to 0.1 volts. Then, the detection voltage supply device 30 provides the detection voltage 302, and the pre-charge switch 108 is turned on for a pre-charge time (e.g., 20 to 30 microseconds) to fully charge the parasitic capacitance 112 with the pre-charge voltage 402. Since the pre-charge voltage 402 does not pass through the detection impedance 204, the parasitic capacitance 112 can be quickly fully charged to 0.1 volts.

[0054] Based on the above, the present invention can thus be obtained. Figure 5 Voltage waveform diagram, Figure 5 This is an experimental voltage waveform diagram of the detection voltage 114 of the present invention. Figure 5 As shown, before the first time point t1, the detection voltage supply device 30 has provided the detection voltage 302, the pre-charge switch 108 has been turned on for the pre-charge time so that the parasitic capacitor 112 has been fully charged, and the pre-charge switch 108 has just been turned off. The second time point t2 minus the first time point t1 (i.e., the waiting time described later) equals 70 microseconds; that is, after 70 microseconds, a 10% drop in the detection voltage 114 can be detected (i.e., 0.1 - 0.09 = 0.01, 0.01 / 0.1 = 10%). In other words, based on the detection impedance 204 being set to 100 MΩ and the above settings, a drop in the detection voltage 114 can be detected before the detection voltage 114 reaches a steady state.

[0055] Next, the above experiment was repeated several times, with the detection impedance 204 sequentially set to less than 100 MΩ (e.g., 80 MΩ, 60 MΩ, etc.), while the other settings and steps remained the same. The phenomenon of the detection voltage 114 decreasing after the first time point t1 could still be detected similarly. However, when the detection impedance 204 was set to 10 MΩ while the other settings and steps remained the same, the phenomenon of the detection voltage 114 decreasing after the first time point t1 became less noticeable. Even when the detection impedance 204 was set to less than 10 MΩ (e.g., 1 MΩ) while the other settings and steps remained the same, the detection voltage 114 increased after the first time point t1, thus obtaining... Figure 6 Voltage waveform diagram, Figure 6 This is another experimental voltage waveform diagram of the detection voltage 114 of the present invention. For example... Figure 6As shown, the rise of the detection voltage 114 by 100% can be detected by subtracting the first time point t1 (70 microseconds) from the second time point t2 (i.e., 0.2 - 0.1 = 0.1, 0.1 / 0.1 = 100%). In other words, based on the detection impedance 204 being set to 1 MΩ and the above settings, the rise of the detection voltage 114 can be detected before it reaches a steady state.

[0056] As can be seen from the above experiments, by properly setting these settings and steps, the detection voltage 114 can be detected to be decreasing or increasing before it reaches a steady state. In the above embodiment, if the detection voltage 114 is detected to be decreasing, the detection impedance 204 will be greater than 10 MΩ, and if the detection voltage 114 is detected to be increasing, the detection impedance 204 will be less than 10 MΩ. Here, 10 MΩ is the dividing line, which is the preset resistance value described later in this article. This preset resistance value will change with different settings, depending on the designer's needs.

[0057] However, the resistance value of the detection impedance 204 in this printed circuit board impedance detection is very large (e.g., above 1M ohm). Therefore, the present invention is designed based on the large preset resistance value (e.g., 10M ohms). That is, based on the above embodiment, if the detection voltage 114 is detected to be decreasing, the detection impedance 204 will be greater than 10M ohms, and the detection impedance 204 being greater than 10M ohms can be inferred to mean that the printed circuit board lines in the detection impedance 204 are not connected (i.e., similar to an open circuit); if the detection voltage 114 is detected to be increasing, the detection impedance 204 will be less than 10M ohms, and the detection impedance 204 being less than 10M ohms can be inferred to mean that the printed circuit board lines in the detection impedance 204 are connected (i.e., similar to a short circuit).

[0058] In other words, this invention does not actually calculate the resistance value of the detection impedance 204 after the detection voltage 114 reaches a steady state to determine whether the detection impedance 204 is abnormal (because such an overall detection time would be very long). Instead, it detects whether the detection voltage 114 is decreasing or increasing before the detection voltage 114 reaches a steady state to determine whether the detection impedance 204 is greater than or less than the preset resistance value, and further determines whether the detection impedance 204 is abnormal (if the detection voltage 114 is decreasing, the detection impedance 204 is greater than the preset resistance value, and based on the preset resistance value of 10M ohms, the detection impedance 204 being greater than the preset resistance value is similar to an open circuit; if the detection voltage 114 is increasing, the detection impedance 204 is less than the preset resistance value, and based on the preset resistance value of 10M ohms, the detection impedance 204 being less than the preset resistance value is similar to a short circuit).

[0059] Please refer to Figure 7 This is a flowchart illustrating the method of operating the printed circuit board impedance detection device of the present invention; please refer to... Figure 8 This is a circuit block diagram of a specific embodiment of the printed circuit board impedance detection device 10 of the present invention; please refer to... Figure 9 This is a circuit block diagram of another specific embodiment of the printed circuit board impedance detection device 10 of the present invention. Figure 9 The components shown are Figure 8 For the sake of simplicity, the same components shown will not be described again here.

[0060] like Figure 8 As shown, the printed circuit board impedance detection device 10 of the present invention is applied to a printed circuit board 20, a detection voltage supply device 30, and a pre-charge voltage supply device 40. The printed circuit board 20 includes a plurality of printed circuit board lines 202, which form a detection impedance 204. The printed circuit board impedance detection device 10 includes a controller 102, a voltage detector 104, a detection resistor 106, a pre-charge switch 108, and a switching circuit 110. The switching circuit 110 has a plurality of parasitic capacitances 112, and the above components are electrically connected to each other. Figure 9 As shown, the switching circuit 110 includes a plurality of upper switches 116 and a plurality of lower switches 118, and these components are electrically connected to each other.

[0061] Please also refer to Figure 7 , Figure 8 and Figure 9 ;like Figure 7 As shown, the method of operating the printed circuit board impedance detection device of the present invention includes the following steps:

[0062] Step S02: Control the upper switches 116 and the lower switches 118 to make the printed circuit board lines 202 form the detection impedance 204. Then, the method proceeds to step S04.

[0063] Step S04: Turn on the pre-charge switch 108. Then, the method proceeds to step S06. Step S04 can be interchanged with step S02, that is, step S04 precedes step S02, or both can be performed simultaneously.

[0064] Step S06: Do not turn on the pre-charge switch 108. Next, the method proceeds to step S08. The period between turning on and not turning on the pre-charge switch 108 constitutes a pre-charge time.

[0065] Step S08: Wait for a certain period of time. Then, the method proceeds to step S10.

[0066] Step S10: Detect and obtain a detection voltage 114 of the detection resistor 106. Then, the method proceeds to step S12.

[0067] Step S12: Determine whether the resistance value of the detection impedance 204 is greater than or less than a preset resistance value. Then, the method proceeds to step S14.

[0068] Step S14: Is there another detection impedance 204 that needs to be determined? If yes, the method returns to step S02; if not, the method proceeds to step S16.

[0069] Step S16: End.

[0070] Please refer to the following: Figure 8 The controller 102 is configured to control the precharge switch 108 so that the parasitic capacitors 112 are charged for a precharge time by a precharge voltage 402 provided by the precharge voltage supply device 40; the controller 102 is configured to detect and obtain a detection voltage 114 of the detection resistor 106 by means of the voltage detector 104; the controller 102 is configured to determine the detection voltage 114 to determine the relationship between a resistance value of the detection impedance 204 and a preset resistance value.

[0071] Furthermore, if the controller 102 determines that the detected voltage 114 is greater than the pre-charge voltage 402 (e.g., as mentioned above) Figure 6 If the detected voltage 114 rises, the controller 102 is configured to determine that the resistance value of the detection impedance 204 is less than or equal to the preset resistance value; if the controller 102 determines that the detected voltage 114 is less than or equal to the pre-charge voltage 402 (e.g., as described above)... Figure 5 If the detection voltage 114 drops, then the controller 102 is configured to determine that the resistance value of the detection impedance 204 is greater than the preset resistance value.

[0072] Furthermore, the controller 102 is configured to determine the pre-charge time based on the detection resistor 106 and the parasitic capacitances 112. The pre-charge voltage supply device 40 provides the pre-charge voltage 402 based on the default resistance value, which is inversely proportional to the pre-charge voltage 402 (e.g., if the default resistance value is 10 MΩ (the smaller the value), then the pre-charge voltage 402 is 0.1 volts (the larger the value); if the default resistance value is 20 MΩ (the larger the value), then the pre-charge voltage 402 is 0.05 volts (the smaller the value)).

[0073] Please refer to the following: Figure 9The detection voltage supply device 30 transmits a detection voltage 302 to the switching circuit 110. The controller 102 is configured to control the upper switches 116 and the lower switches 118 of the switching circuit 110 so that the printed circuit board lines 202 form the detection impedance 204. The controller 102 is configured to detect and obtain the detection voltage 114 of the detection resistor 106 by means of the voltage detector 104 after the pre-charge time plus a waiting time. The pre-charge switch 108 may be, for example, but not limited to, a transistor switch; the upper switches 116 may be, for example, but not limited to, a plurality of transistor switches; and the lower switches 118 may be, for example, but not limited to, a plurality of transistor switches. In one specific embodiment of the invention, the detection voltage 302 is 10 volts, the detection resistor 106 is 10 kΩ, the pre-charge voltage 402 is 0.1 volts, the pre-charge time is 20 to 30 microseconds (intended to pre-charge the parasitic capacitors 112), the waiting time is 70 microseconds, and the preset resistance value is 10 MΩ.

[0074] Furthermore, the waiting time is directly proportional to the detection resistor 106; that is, the smaller the detection resistor 106, the shorter the waiting time; and the larger the detection resistor 106, the longer the waiting time. The waiting time is also directly proportional to the detection impedance 204; that is, the smaller the detection impedance 204, the shorter the waiting time; and the larger the detection impedance 204, the longer the waiting time.

[0075] Furthermore, the first terminals of the upper switches 116 are connected to the voltage detection supply device 30, the second terminals of the upper switches 116 are connected to the controller 102, the third terminals of the upper switches 116 are connected to the printed circuit board lines 202 and the first terminals of the lower switches 118, the second terminals of the lower switches 118 are connected to the controller 102, and the third terminals of the lower switches 118 are connected to the voltage detector 104, the detection resistor 106, and the pre-charge switch 108. The controller 102 is configured to turn on one of the upper switches 116 and not turn on the remaining upper switches 116, and not turn on the lower switch 118 closest to the turned-on upper switch 116, and turn on the remaining lower switches 118, thereby forming the detection impedance 204.

[0076] The advantage of this invention is that it can quickly determine whether there are any abnormalities in the manufactured printed circuit board.

[0077] However, the above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made according to the claims of the present invention should still fall within the scope of protection intended by the patent of the present invention. The present invention may also have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims. In summary, the present invention possesses industrial applicability, novelty, and inventiveness, and its structure has not been seen in similar products or publicly used, fully meeting the requirements for an invention patent application. Therefore, this application is filed in accordance with the Patent Law.

Claims

1. A printed circuit board impedance detection device, characterized in that, Applied to a printed circuit board and a pre-charge voltage supply device, the printed circuit board includes a plurality of printed circuit board lines forming a sensing impedance, the printed circuit board impedance sensing device comprising: One controller; A voltage detector is electrically connected to the controller; A detection resistor is electrically connected to the voltage detector; A pre-charge switch, electrically connected to the controller, the voltage detector, and the sensing resistor; and A switching circuit is electrically connected to the controller, the voltage detector, the sensing resistor, and the precharge switch. The switching circuit has a plurality of parasitic capacitances; the controller is configured to control the pre-charge switch so that the parasitic capacitances are charged by a pre-charge voltage provided by the pre-charge voltage supply device for a pre-charge time; the controller is configured to detect and obtain a detection voltage of the detection resistor by the voltage detector; the controller is configured to determine the relationship between a resistance value of the detection impedance and a preset resistance value by judging the detection voltage; Specifically, if the controller determines that the detected voltage is greater than the pre-charge voltage, the controller is configured to determine that the resistance value of the detection impedance is less than or equal to the preset resistance value; if the controller determines that the detected voltage is less than or equal to the pre-charge voltage, the controller is configured to determine that the resistance value of the detection impedance is greater than the preset resistance value.

2. The printed circuit board impedance detection device as described in claim 1, characterized in that, The controller is configured to detect and obtain the detection voltage of the detection resistor by means of the voltage detector after the pre-charge time plus a waiting time.

3. The printed circuit board impedance detection device as described in claim 2, characterized in that, The controller is configured to control the switching circuit so that the printed circuit board lines form the detection impedance.

4. The printed circuit board impedance detection device as described in claim 3, characterized in that, The switching circuit includes: Multiple upper switches are electrically connected to the controller.

5. The printed circuit board impedance detection device as described in claim 4, characterized in that, The switching circuit also includes: A plurality of lower switches are electrically connected to the controller, the voltage detector, the detection resistor, the precharge switch, and the upper switches.

6. The printed circuit board impedance detection device as described in claim 5, characterized in that, The controller is configured to control the upper and lower switches to cause the printed circuit board lines to form the detection impedance.

7. The printed circuit board impedance detection device as described in claim 6, characterized in that, The precharge switch is a transistor switch.

8. The printed circuit board impedance detection device as described in claim 7, characterized in that, These upper switches are multiple transistor switches.

9. The printed circuit board impedance detection device as described in claim 8, characterized in that, These lower switches are multiple transistor switches.

10. The printed circuit board impedance detection device as described in claim 9, characterized in that, The detection resistor is 10K ohms, the pre-charge voltage is 0.1 volts, the pre-charge time is 20 to 30 microseconds, the waiting time is 70 microseconds, and the preset resistance value is 10M ohms.

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