Double-wire type anti-static wrist strap monitoring device

Abstract

The invention relates to a double-wire type anti-static wrist strap monitoring device which comprises a double-wire wrist strap provided with an electrode used for making contact with the wrist of the human body; the wrist strap continuous monitor is connected with the double-wire wrist strap through an adapter box, and the wrist strap continuous monitor host is used for monitoring the voltage state of the wrist of the human body and releasing the voltage on the electrode on the double-wire wrist strap; the switching box is used for adjusting the on-off state of the double-wire wrist strap and the wrist strap continuous monitor host; and when the double-line wrist strap and the wrist strap continuous monitor host are in a disconnected state, the wrist strap continuous monitor host judges the insertion state of the wrist strap by using the switching box. According to the invention, the connection condition of the double-wire wrist strap can be distinguished, the access resistance of the double-wire wrist strap can be calculated and the contact voltage value can also be calculated under the condition that an operator accidentally touches the external voltage in the operation process, and whether to give an alarm or not is determined according to the condition.

Description

Technical Field

[0001] The invention relates to the technical field of electrostatic protection, and in particular to a two-wire anti-static wrist strap monitoring device. Background Art

[0002] The anti-static wrist strap is the most commonly used anti-static product in the electrostatic protection area (EPA). Usually one end of its electrode is connected to the ground connection point, and the other end of the electrode is worn on the wrist in contact with the skin. Its working principle is to discharge the static charge accumulated on the operator in time to prevent the static electricity of the human body from causing static damage to static sensitive devices and products.

[0003] Anti-static wrist straps are mainly divided into two types: wired and wireless. Wireless anti-static wrist straps use the principle of corona discharge to dissipate some static electricity. Wireless anti-static wrist straps using the principle of corona discharge cannot effectively ensure that the human body potential is reduced to a certain level and are not allowed to be used in strict places.

[0004] Anti-static wrist straps are divided into single-wire wrist straps and double-wire wrist straps according to the wrist contact point. The grounding end of a single-wire wrist strap is usually a single-contact metal form such as a banana plug, button, or crocodile clip. A metal sheet is connected to the wristband end of a single-wire wrist strap, which contacts the skin when worn. The grounding end of a double-wire wrist strap is usually a 3.5mm audio plug or a double banana head, with two contact electrodes. There are also two metal sheet electrodes at the end of the wrist strap, which contact the human skin when worn.

[0005] In actual work, the most likely problem is that the resistance of the grounding path through the wristband is too high due to various reasons, exceeding the range specified by the standard. There are many reasons for this result, such as the internal wire of the wristband is broken, the elastic band of the wristband is aging, resulting in the wristband electrode not contacting the skin, etc.

[0006] In order to continuously monitor the ground path resistance of the anti-static wrist strap worn by personnel, a circuit can be designed at the ground end of the wrist strap to achieve two functions: the first is the grounding function, and the second is the function of measuring the path resistance. One end of the path resistance is the grounding electrode end, and the other end is the human body itself.

[0007] According to Ohm's law, R=U / I. Only when the voltage and current at both ends of the resistor are known at the same time can the resistance value be calculated. When the single-line anti-static wrist strap is working, only the grounding electrode is connected to the jack, and one end of the human body is not connected to the circuit. In theory, it is impossible to calculate the path resistance. Because only one end of the resistor is connected to the circuit, the other end is suspended and the resistance cannot be calculated. Therefore, theoretically, it is impossible to achieve the grounding path resistance of personnel by wearing a single-line anti-static wrist strap. The single-line anti-static wrist strap continuous monitor sold on the market claims to be able to monitor whether a person is wearing a wrist strap. It does not use the principle of measuring resistance, but the principle of capacitance. It determines whether a person is in contact with the upper wrist strap electrode by monitoring the change in capacitance caused by the human body contacting the upper wrist strap electrode. Although this principle can distinguish whether the human skin is in contact with the wrist strap electrode with a certain probability, it does not meet the requirements of the relevant standards for the grounding conduction resistance. It is not rigorous, and there is a certain probability of false alarm and missed alarm.

[0008] The Chinese patent with the publication number CN108226648B discloses a two-wire anti-static wrist strap and a real-time grounding monitoring device, which uses a two-wire anti-static wrist strap to monitor and alarm the grounding path resistance of the human wrist strap and the human body voltage. While the device realizes the grounding of personnel through the wrist strap, the voltage applied by the test circuit on the human body is also 0, realizing the 0 voltage measurement principle, but the patent has the following disadvantages: 1. After the device is powered on, if there is no staff at a certain workstation and the wrist strap is not inserted, an alarm will be generated at this time because the path resistance is too large. 2. The method of calculating the resistance value with two separate branches and then summing them to obtain the path resistance, when there is no external input voltage, the resistance value is roughly correct, but if the voltage V3 is applied to the human body, the calculated value of the path resistance value is not very accurate. Summary of the invention

[0009] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a two-wire anti-static wrist strap monitoring device, which distinguishes between the two situations that the wrist strap is not inserted and the wrist strap is inserted but the path resistance exceeds the limit. When there is an external voltage applied during operation, the accurate path resistance value and the external input voltage value can be calculated, thereby improving the system's adaptability to the external environment and measurement accuracy.

[0010] To achieve the above-mentioned purpose, the present invention provides a two-wire anti-static wrist strap monitoring device, comprising:

[0011] A two-wire wristband having electrodes for contacting a human wrist;

[0012] A wristband continuous monitor is connected to the two-wire wristband via an adapter box, and the main unit of the wristband continuous monitor is used to monitor the voltage state of the human wrist and release the voltage on the electrodes on the two-wire wristband;

[0013] The adapter box is used to adjust the on / off status of the two-wire wristband and the wristband continuous monitoring instrument host;

[0014] When the two-wire wristband and the wristband continuous monitoring instrument host are in a disconnected state, the wristband continuous monitoring instrument host uses the adapter box to determine the insertion state of the wristband.

[0015] According to a technical solution of the present invention, the wristband continuous monitor includes a monitor applied voltage V0, a ​​monitor applied voltage -V0, a ​​resistor R1, a resistor R1', a resistor R2, a resistor R2', a ground terminal, a C1 input terminal, and a C2 input terminal;

[0016] The voltage output end of the voltage source V0 is connected to one end of the resistor R1;

[0017] The other end of the resistor R1 is connected to one end of the resistor R2 and the input end of C1 at the same time;

[0018] The other end of the resistor R2 is simultaneously connected to one end of the resistor R2', the G1 input end, and the ground end;

[0019] The other end of the resistor R2' is connected to one end of the resistor R1' and the input end of C2 at the same time;

[0020] The other end of the resistor R1 ′ is connected to the voltage output end of the voltage source - V0 .

[0021] According to a technical solution of the present invention, the adapter box includes a C1 output terminal, a C2 output terminal, a G1 output terminal, a B1 input terminal, and a B2 input terminal;

[0022] When the adapter box is connected to the two-wire wristband, the B1 input terminal is connected to the C1 output terminal;

[0023] The B2 input terminal is connected to the C2 output terminal;

[0024] When the connection between the adapter box and the two-wire wristband is disconnected, the G1 output terminal is connected to the C1 output terminal;

[0025] The C1 output terminal is adapted to the C1 input terminal, the C2 output terminal is adapted to the C2 input terminal, and the G1 output terminal is adapted to the G1 input terminal.

[0026] According to a technical solution of the present invention, the two-wire wristband further includes a resistor R3 and a resistor R3';

[0027] The two ends of the resistor R3 are respectively connected to the input end of B1 and an electrode contacting a human wrist;

[0028] The two ends of the resistor R3' are respectively connected to the B2 input end and another electrode contacting the human wrist.

[0029] According to a technical solution of the present invention, the wristband continuous monitor also includes an alarm circuit, which generates an alarm signal according to the equivalent path resistance of the two-wire anti-static wristband monitoring device, the external applied voltage and the condition of the adapter box.

[0030] According to a technical solution of the present invention, the wristband continuous monitor determines the status of the adapter box according to the following formula:

[0031]

[0032] V1=0

[0033] Among them, R a is the equivalent path resistance of the two-wire wristband when not inserted, R1 is the resistance value of resistor R1, R2 is the resistance value of resistor R2, V0 is the output voltage of voltage source V0, V1 is the voltage value of the input terminal of C1, and V′1 is the voltage value of the input terminal of C2.

[0034] According to a technical solution of the present invention, the alarm circuit calculates the equivalent path resistance and the voltage applied externally to the human body according to the following formula, and an alarm is triggered when the equivalent path resistance and the voltage applied externally to the human body exceed a threshold value;

[0035]

[0036] Among them, R b is the equivalent path resistance of the two-wire wristband when inserted, I3 is the current value of the input terminal of C1, I′3 is the current value of the input terminal of C2, V1 is the voltage value of the input terminal of C1, V′1 is the voltage value of the input terminal of C2, and V3 is the voltage applied to the outside of the human body.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. Using a transfer box structure similar to the characteristics of a 3.5mm socket, when the two-wire wristband is not inserted into the transfer box, the circuit parameter characteristics are obvious and can be clearly distinguished. When the two-wire wristband is not inserted or the two-wire wristband is inserted but the circuit is open, the system will not alarm.

[0039] 2. The calculation formula proposed in the present invention can calculate both the resistance of the wristband path and the contact voltage value when a person accidentally touches an external voltage during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A schematic diagram schematically showing the circuit equivalent of the two-wire anti-static wrist strap monitoring device of the present invention;

[0042] Figure 2 A schematic diagram of a two-wire anti-static wrist strap monitoring device of the present invention is schematically shown;

[0043] Figure 3 A schematic diagram schematically shows a circuit equivalent diagram of a two-wire anti-static wrist strap monitoring device of the present invention with an external voltage V3 input;

[0044] Figure 4 The schematic diagram schematically shows the circuit equivalent of the two-wire anti-static wrist strap monitoring device of the present invention when it is inserted into a two-wire wrist strap. DETAILED DESCRIPTION

[0045] The description of the embodiments of this specification should be combined with the corresponding drawings, which should be considered as part of the complete specification. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated for simplification or convenience. Furthermore, the parts of each structure in the drawings will be described separately. It is worth noting that the elements not shown in the drawings or not described in words are in a form known to ordinary technicians in the relevant technical field.

[0046] The description of the embodiments herein and any reference to directions and orientations are only for the convenience of description and are not to be construed as any limitation on the scope of protection of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination, and the present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0047] like Figures 1 to 4 As shown, the present invention proposes a two-wire anti-static wrist strap monitoring device, the structure of the two-wire anti-static wrist strap monitoring device is as shown in Figure 2 As shown, including:

[0048] A two-wire wristband having electrodes for contacting a human wrist;

[0049] The wristband continuous monitor is connected to the two-wire wristband through the adapter box. The main unit of the wristband continuous monitor is used to monitor the voltage state of the human wrist and release the voltage on the electrodes on the two-wire wristband;

[0050] The adapter box is used to adjust the on / off status of the dual-wire wristband and the wristband continuous monitoring instrument host;

[0051] When the two-wire wristband and the wristband continuous monitoring instrument host are in a disconnected state, the wristband continuous monitoring instrument host uses the adapter box to determine the insertion state of the wristband.

[0052] The main function of the wristband continuous monitor is to determine whether the human body is in good contact with the wristband electrodes by measuring the loop resistance of the two-wire wristband. The auxiliary function is to monitor the voltage of the human body. One source of this voltage is that the human body contacts an external voltage source due to misoperation. After the human body wears the anti-static wristband, the wristband is inserted into the adapter box, and the resistance of the wristband insertion end (point B1 and point B2) is measured to determine whether the human body is in reliable contact with the two wristband electrodes. The static charge accumulated by the human body is discharged through the grounding path resistance of the wristband.

[0053] The wristband continuous monitor is a fixed end and can be connected to multiple adapter boxes. The adapter boxes are set near the operator. The operator wears the dual-wire wristband and inserts the dual-wire wristband into the adapter box. The wristband continuous monitor will alarm when it detects abnormal conditions.

[0054] The circuit of the two-wire anti-static wrist strap monitoring device is as follows Figure 1 shown.

[0055] The wristband continuous monitor includes a monitor applied voltage V0, a ​​monitor applied voltage -V0, a ​​resistor R1, a resistor R1', a resistor R2, a resistor R2', a ground terminal, a C1 input terminal, and a C2 input terminal;

[0056] The voltage output terminal of the voltage source V0 is connected to one end of the resistor R1;

[0057] The other end of the resistor R1 is connected to one end of the resistor R2 and the input end of C1 at the same time;

[0058] The other end of the resistor R2 is connected to one end of the resistor R2', the input end of G1, and the ground end at the same time;

[0059] The other end of the resistor R2' is connected to one end of the resistor R1' and the input end of C2 at the same time;

[0060] The other end of the resistor R1 ′ is connected to the voltage output end of the voltage source -V0 .

[0061] The resistance values ​​of the resistor R1 and the resistor R1 ′ are equal, and the resistance values ​​of the resistor R2 and the resistor R2 ′ are equal.

[0062] In the present invention, voltage V0 and voltage -V0 are applied in the wristband continuous monitor, the purpose of which is to put the entire circuit in a charged working state, so as to facilitate monitoring of the conditions of the human wrist and the two-wire wristband through the parameters of the circuit.

[0063] The adapter box includes a C1 output terminal, a C2 output terminal, a G1 output terminal, a B1 input terminal, and a B2 input terminal;

[0064] When the adapter box and the two-wire wrist strap are connected, the B1 input terminal and the C1 output terminal are connected;

[0065] B2 input terminal and C2 output terminal are connected;

[0066] When the connection between the adapter box and the two-wire wrist strap is disconnected, the G1 output terminal and the C1 output terminal are connected;

[0067] The C1 output terminal is adapted to the C1 input terminal, the C2 output terminal is adapted to the C2 input terminal, and the G1 output terminal is adapted to the G1 input terminal.

[0068] The circuit equivalent diagram of the adapter box is as follows Figure 1 As shown, when the adapter box is not plugged in Figure 4 Point C1 in the figure is connected to point G1 due to elasticity; when the dual-wire wristband is inserted into the adapter box, point C1 is connected to point B1, and point C2 is connected to point B2. The circuit is as follows: Figure 4 shown.

[0069] The two-wire wristband also includes a resistor R3 and a resistor R3';

[0070] The two ends of the resistor R3 are respectively connected to the input end of B1 and an electrode contacting the human wrist;

[0071] Both ends of the resistor R3' are connected to the input end of B2 and another electrode contacting the human wrist respectively.

[0072] The resistance values ​​of the resistor R3 and the resistor R3' are equal.

[0073] The wristband continuous monitor also includes an alarm circuit, which generates an alarm signal according to the equivalent path resistance of the two-wire anti-static wristband monitoring device, the external applied voltage and the condition of the adapter box.

[0074] The wristband continuous monitor determines the status of the adapter box according to the following formula:

[0075]

[0076] V1=0

[0077] Among them, R a is the equivalent path resistance of the two-wire wristband when not inserted, R1 is the resistance value of resistor R1, R2 is the resistance value of resistor R2, V0 is the output voltage of voltage source V0, V1 is the voltage value at the input end of C1, and V′1 is the voltage value at the input end of C2.

[0078] According to the above resistance R a, V1, and V′1 jointly determine whether the two-wire wristband is not inserted or inserted but open-circuited. In this case, no alarm is given.

[0079] The alarm circuit calculates the equivalent path resistance and the voltage applied externally to the human body according to the following formula, and alarms when the equivalent path resistance and the voltage applied externally to the human body exceed the threshold value;

[0080]

[0081] Among them, R b is the equivalent path resistance of the two-wire wristband when inserted, I3 is the current value at the input end of C1, I′3 is the current value at the input end of C2, V1 is the voltage value at the input end of C1, V′1 is the voltage value at the input end of C2, and V3 is the voltage applied to the outside of the human body.

[0082] When the two-wire wristband is inserted into the adapter box, the circuit equivalent diagram is as follows Figure 4 As shown, calculate the equivalent path resistance R b When Figure 3 , resistor R b It is the sum of the resistance values ​​of resistor Rx and resistor Ry.

[0083] When the human body comes into contact with an external voltage source due to accidental reasons, the human body will become charged and an alarm must be given in time. The solution of the present invention can accurately calculate the equivalent path resistance when an external voltage V3 is applied. When a person accidentally touches an external voltage during operation, both the wristband path resistance and the contact voltage value can be calculated.

[0084] like Figure 4 As shown, the interface of the wristband continuous monitor is connected to the grounding terminal of the two-wire wristband, and the wrist of the person is connected to the electrode part of the wristband. Points B1 and B2 are the two grounding points of the two-wire wristband, points A1 and A2 are the two wristband electrodes of the two-wire wristband, and point A3 is another point on the human body. In the figure. The voltages V0 and -V0 applied inside the wristband continuous monitor are small voltages with opposite polarities and the same amplitude. Because the resistance values ​​of resistors R1 and R1' are equal, the resistance values ​​of resistors R2 and R2' are equal, and the resistance values ​​of resistors R3 and R3' are equal, due to the symmetry of the circuit, the voltages V1 and V1' at points B1 and B2 and the voltages V2 and V2' at points A1 and A2 are also opposite in polarity and the same in amplitude. At the same time, the human body can also be regarded as symmetrical, so it can be considered that the resistances of resistors R5 and R6 are equal, then the voltage presented to the outside by point A3 is 0, thereby achieving that the voltage at any other point of the human body is 0 during circuit operation. The resistors R2 and R3 as well as the resistors R2' and R3' realize two grounding paths for discharging static electricity generated by the human body.

[0085] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A two-wire anti-static wrist strap monitoring device, characterized in that: include: A two-wire wristband having electrodes for contacting a human wrist; A wristband continuous monitor is connected to the two-wire wristband via an adapter box, and the main unit of the wristband continuous monitor is used to monitor the voltage state of the human wrist and release the voltage on the electrodes on the two-wire wristband; The adapter box is used to adjust the on / off status of the two-wire wristband and the wristband continuous monitoring instrument host; When the two-wire wristband and the wristband continuous monitoring instrument host are in a disconnected state, the wristband continuous monitoring instrument host uses the adapter box to determine the insertion state of the wristband.

2. The two-wire anti-static wrist strap monitoring device according to claim 1 is characterized in that: The wristband continuous monitor includes a monitor applied voltage V0, a ​​monitor applied voltage -V0, a ​​resistor R1, a resistor R1', a resistor R2, a resistor R2', a ground terminal, a C1 input terminal, and a C2 input terminal; The voltage output end of the voltage source V0 is connected to one end of the resistor R1; The other end of the resistor R1 is connected to one end of the resistor R2 and the input end of C1 at the same time; The other end of the resistor R2 is simultaneously connected to one end of the resistor R2', the G1 input end, and the ground end; The other end of the resistor R2' is connected to one end of the resistor R1' and the input end of C2 at the same time; The other end of the resistor R1 ′ is connected to the voltage output end of the voltage source - V0 .

3. The two-wire anti-static wrist strap monitoring device according to claim 2 is characterized in that: The adapter box includes a C1 output terminal, a C2 output terminal, a G1 output terminal, a B1 input terminal, and a B2 input terminal; When the adapter box is connected to the two-wire wristband, the B1 input terminal is connected to the C1 output terminal; The B2 input terminal is connected to the C2 output terminal; When the connection between the adapter box and the two-wire wristband is disconnected, the G1 output terminal is connected to the C1 output terminal; The C1 output terminal is adapted to the C1 input terminal, the C2 output terminal is adapted to the C2 input terminal, and the G1 output terminal is adapted to the G1 input terminal.

4. The two-wire anti-static wrist strap monitoring device according to claim 3 is characterized in that: The two-wire wristband also includes a resistor R3 and a resistor R3'; The two ends of the resistor R3 are respectively connected to the input end of B1 and an electrode contacting a human wrist; The two ends of the resistor R3' are respectively connected to the B2 input end and another electrode contacting the human wrist.

5. The two-wire anti-static wrist strap monitoring device according to claim 1 is characterized in that: The wristband continuous monitor also includes an alarm circuit, which generates an alarm signal according to the equivalent path resistance of the two-wire anti-static wristband monitoring device, the external applied voltage and the condition of the adapter box.

6. The two-wire anti-static wrist strap monitoring device according to claim 2 or 3, characterized in that: The wristband continuous monitor determines the status of the adapter box according to the following formula: V1＝0 Among them, R a is the equivalent path resistance of the two-wire wristband when not inserted, R1 is the resistance value of resistor R1, R2 is the resistance value of resistor R2, V0 is the output voltage of voltage source V0, V1 is the voltage value of the input terminal of C1, and V1′ is the voltage value of the input terminal of C2.

7. The two-wire anti-static wrist strap monitoring device according to claim 2 or 3, characterized in that: The alarm circuit calculates the equivalent path resistance and the voltage applied externally to the human body according to the following formula, and alarms when the equivalent path resistance and the voltage applied externally to the human body exceed a threshold value; Among them, R b is the equivalent path resistance of the two-wire wristband when inserted, I3 is the current value of the input terminal of C1, I′3 is the current value of the input terminal of C2, V1 is the voltage value of the input terminal of C1, V1′ is the voltage value of the input terminal of C2, and V3 is the voltage applied to the outside of the human body.

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