TWM517823U - Multifunctional pointer-meter with high voltage alarm and protection - Google Patents

Description

Multi-function pointer meter with high voltage protection and warning

The present invention relates to an electric meter, in particular to a multi-function pointer electric meter with high voltage protection and warning.

The pointer meter is a traditional measuring tool. In recent years, due to the rise of digital multimeters, pointer meters have gradually declined. However, at present, some users are accustomed to determine the size of the object to be tested by the amplitude of the pointer deflection, so the pointer meter still occupies a certain market. Compared with the digital multimeter, the main disadvantages of the pointer meter are two: First, the high voltage protection is insufficient: the digital multimeter can withstand hundreds of volts of high voltage in various measurement modes and gear positions, while the pointer meter is measuring When the voltage is high, if the wrong mode or gear position is selected, the fuse inside the meter is blown, but the head is damaged, and even the electrical equipment to be tested is damaged or dangerous. Second, the function is insufficient: Currently, the market pointer meter mainly includes DC voltage, AC voltage, resistance, DC current and other functions. Other functions in the digital meter include AC current, capacitance, frequency and other functions are not provided, and the digital multimeter can be internally The analog/digital converter (ADC) and the frequency operation circuit in the integrated circuit (IC) perform various measurement functions.

The reason why the pointer meter has poor protection against high voltage can be explained by the configuration of the DC voltage circuit of Fig. 1. When the pointer meter performs voltage measurement, it transmits the signal to be tested. The resistance between the input (Input 1) and the pointer head is converted into a current to drive the pointer to deflect. The lower the gear, the smaller the resistor must be, so that the low voltage signal generates enough current. Drive the pointer to deflect. In the first figure, taking the 0.25V gear as an example, the resistance between the input terminal (Input 1) and the meter head is only 5KΩ (3KΩ+2KΩ). If the gear to be measured is measured in this gear position, For example, 220V mains power may cause damage to the meter head because the current is too large and the fuse has not been blown. The same is true for the measurement of the resistance. In the lower gear position, the lower the input impedance, if the user wants to measure the high voltage, but the measurement mode is switched to the low resistance file, and the head may be damaged or The internal resistance of the meter is burned.

In contrast, digital multimeters, taking the voltage measurement as an example, the input terminal is usually protected by a large resistance of 10MΩ, and each gear of the voltage range is further divided by 10MΩ and the electronic switch and the voltage dividing resistor; and the resistor or capacitor is executed. During the measurement, the signal source is connected to the object to be tested through the PTC thermistor. When there is a high voltage input externally, the resistance of the PTC resistor will increase rapidly due to the increase of the current, thereby protecting the meter.

Although the function of the pointer meter is small, for a user who is not very familiar with electrical knowledge, or for various unknown situations that may be faced in actual use, in the process of measurement, the user When measuring an unknown power source or an unknown object to be tested, it is still possible to misjudge the electrical properties of the object to be tested from the beginning. In addition, if the way of using it is not correct, even if the pointer is electrically coupled to the object to be tested, there are other transactions temporarily and the meter is continuously connected to the unknown object to be tested. The object has a high voltage, and the object to be tested is connected to the power supply of the plant or building. This condition causes the instrument to burn down, and the voltage of the power supply of the building or the factory area may drop instantaneously, and may even cause a power jump. For another example, if the object to be tested is an alternating current (AC) voltage source, and the user does not know, the base In the case of mis-cognition or erroneous operation, the meter is switched to the measurement position of the DC voltage to measure the signal source. What is measured at this point may be a value that approaches zero. If this is the case, not only the measured value is wrong (mistaken to be a DC voltage close to zero), but also the user mistakenly believes that the object under test has no voltage (or the voltage approaches zero), resulting in It is misunderstood that physical contact is not dangerous, but in fact the amplitude of this AC voltage may be quite large, which may expose the contactor to the risk of being injured and even endangering personal safety.

For example, in an electric meter, the input end of the measuring current is usually also low impedance. If the user measures the voltage, the measuring probe is mistakenly inserted into the measuring current slot, and the equivalent is measured. When the time is too long, it is easy to cause the fuse to blow, and it is easy to cause damage to the meter.

Therefore, how to provide a warning function in the pointer meter for such unknown electrical measurement object, when the voltage of the value to be measured different from the gear position is detected, the user can be immediately alerted to improve the use. The safety of the measurement, and this also helps to extend the life of the meter; in addition, how to make the pointer meter also have a variety of different functions of the digital meter (such as measuring AC current, capacitance, frequency and other functions), become The new direction of pointer meter development.

The novel uses the technology of the digital electric meter to be transferred to the pointer electric meter, thereby giving the pointer electric meter the functions possessed by the multi-digit electric meter and having the protection against high voltage.

According to a preferred embodiment of the present invention, the multi-function pointer meter with high voltage protection and warning is used when the user electrically couples one of the plurality of input terminals of the multi-function pointer meter to a test object. When the absolute value of the potential of the measured object exceeds the absolute value of the preset limit value, the enable device is enabled to alert the user to include the following: the pointer meter, the comparison circuit and the warning device. Wherein, the pointer meter is used according to the measurement mode selected by the user, correspondingly The turntable switch couples the electrical property on the object to be tested through the input end, and obtains the corresponding input potential through the electronic switch and the voltage divider to be divided, and is fed into the digital/analog converter for processing, and the value is calculated by the controller. The controller then converts the analog/digital converter into a pointer current according to the numerical control, and rotates a pointer, and the controller presets a maximum pointer current. When the pointer current of the value conversion is greater than the maximum pointer current, the maximum pointer current is output. The comparison circuit is configured to compare the absolute value of the corresponding input potential with the absolute value of the preset limit value, and generate a high-voltage prompt signal when the absolute value of the corresponding input potential is greater than the absolute value of the preset limit value, and the preset limit value is The absolute value is a value larger than the absolute value of the full scale (Full Scale) voltage value of the analog/digital converter. The warning device enables (Enable) when the controller receives the high voltage prompt signal to remind the user to pay attention.

According to a preferred embodiment of the present invention, the multi-function pointer meter with high voltage protection and warning is used when the user electrically couples the object to be tested with multiple inputs of the multi-function pointer meter. When the absolute value of the potential exceeds the absolute value of the preset limit value, a warning is generated to remind the user to include: the pointer meter, the comparison circuit and the warning device. Wherein, the pointer meter is used for coupling the electrical input on the object to be tested through the corresponding turntable switch according to the measurement mode selected by the user, and the corresponding input potential is obtained by dividing the voltage through the electronic switch and the voltage divider. After being fed into the analog/digital converter, the value is calculated by the controller, and the controller converts the digit/analog converter into a pointer current according to the value, and rotates a pointer, and the controller presets the maximum pointer current, when the value When the pointer current of the conversion is greater than the maximum pointer current, the maximum pointer current is output. The comparison circuit is configured to compare the absolute value of the corresponding input potential with the absolute value of the preset limit value, and generate a high voltage prompt signal when the absolute value of the corresponding input potential is greater than the absolute value of the preset limit value, the preset limit The absolute value of the value is greater than the absolute value of the full scale (full scale) voltage value of the analog/digital converter, and the comparison circuit includes at least a window comparator to pre The positive value of the limit value is taken as the upper threshold voltage, and the negative value of the preset limit value is used as the lower threshold voltage. When the corresponding input potential is greater than the upper threshold voltage or less than the lower threshold voltage, the absolute value of the corresponding input potential is greater than the preset value. The absolute value of the limit value, at least one of the two outputs of the window comparator generates the high voltage prompt signal. The warning device is enabled (Enable) when the controller receives the high voltage prompt signal to remind the user to pay attention.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

INPUT1~INPUT2‧‧‧first to second input

COM‧‧‧ grounding terminal

Rd1~Rd4‧‧‧voltage resistor

Rt1‧‧‧ voltage conversion resistor

N1~n9‧‧‧ nodes

R1~R4‧‧‧Resistance of protection circuit

D1, D2‧‧‧ resistance of voltage conversion circuit

SW1~SW7‧‧‧ switch

CMP1‧‧‧First Comparator

CMP2‧‧‧Second comparator

PMOS1‧‧‧P type gold oxide half field effect transistor

OP1‧‧‧First Operational Amplifier

Rs1‧‧‧ source resistance

HV‧‧‧High voltage prompt signal

R*‧‧‧resistance

C*‧‧‧ capacitor

F1 F2‧‧‧Fuse

100‧‧‧ Turntable switch

200‧‧‧ input

300‧‧‧Protection circuit

400‧‧ ‧ voltage divider

500‧‧‧Voltage conversion circuit

600‧‧‧ analog/digital converter

700‧‧‧ Controller

800‧‧‧Electronic switch

900‧‧‧Signal source circuit

950‧‧ pointer

1000‧‧‧Comparative circuit

1100‧‧‧ Warning device

1105‧‧‧LED

1107‧‧‧ buzzer

1150‧‧‧ integrated circuit

1120‧‧‧frequency operation circuit

1130‧‧‧Digital/analog converter

1 is a DC voltage circuit configuration diagram of a prior art; FIG. 2 is a functional block diagram of a multi-function pointer meter with high voltage protection and warning according to the present invention; FIG. 3 is a high voltage according to the present invention. An embodiment of a multi-function pointer electric meter for protection and warning, wherein a circuit structure diagram of a partial circuit level is displayed; and FIG. 4A is an execution voltage amount according to an embodiment of the multi-function pointer electric meter with high voltage protection and warning according to the present invention. Embodiments of performing signal voltage division and detecting voltage dividing point potential during measurement; FIG. 4B is an embodiment of a multi-function pointer meter with high voltage protection and warning according to the present invention, performing signal measurement when performing voltage measurement Another embodiment of dividing and detecting the voltage of the voltage dividing point; FIG. 5A is an embodiment of the multi-function pointer meter with high voltage protection and warning according to the present invention, detecting the object to be tested when performing resistance measurement Embodiment of potential; and Figure 5B is one of the multi-function pointer meters with high voltage protection and warning according to the present invention Embodiments Embodiments for detecting a potential of a test object when performing capacitance measurement.

The present invention will be described in detail with reference to the following specific embodiments, which are merely intended to illustrate the present invention, and the present invention is not limited to the scope of the embodiments.

In Fig. 2, in the pointer meter, a plurality of input terminals (INPUT 1, INPUT 2) are included, and the user selects the measurement mode and the gear position to be executed by switching the dial switch 100. During the process of switching the dial switch 100, the mechanical switch inside the pointer meter is driven to select the input terminal corresponding to the measurement mode and the related switching action. The information of the measurement mode and gear position selected by the user is transmitted to the controller 700, and the controller 700 controls the electronic switch 800 according to the range and the gear position. The electronic switch 800 is a set of switches connecting the protection circuit and the voltage dividing resistor, and the voltage dividing resistor is a set of resistors of different sizes, as shown in FIG. Through the electronic switch 800, the signal input to the analog/digital converter 600 can be divided to an appropriate potential for measurement. The analog/digital converter 600 converts the input analog signal into a measured value and sends it to the controller 700. In the DC voltage or DC current mode, the value obtained by the analog/digital converter 600 operation is the voltage value or current value of the object to be tested, and the controller 700 transmits this value to the digital/analog converter 1130 for digital/analog conversion. The device 1130 then converts the pointer current output to the pointer 950 according to the magnitude of the value, and pushes the pointer 950 to deflect. The magnitude of the output current is proportional to this value.

In the AC voltage or AC current mode, after the analog/digital converter 600 transmits the converted value to the controller 700, the controller 700 converts the plurality of values into RMS values, averages them, and then transmits them to the digits/analog Converter 1130 converts to a pointer current that drives pointer 950. When measuring passive components such as resistance and capacitance, since the passive component does not generate a signal, control is performed at this time. The device 700 drives the signal source circuit 900 to send a current source to the object to be tested to generate a voltage through the electronic switch 800 for measurement. When measuring the resistance, the voltage difference between the two ends of the object to be tested is obtained by the analog/digital converter 600, and the controller 700 divides the voltage difference by the size of the current source to obtain the resistance value, and the value is transmitted again. The to digital/analog converter 1130 converts to a current that drives the pointer 950 to deflect. When measuring the capacitance, when the current source is transmitted to the capacitor to be tested, the voltage on the capacitor to be tested will change linearly with time, and the controller 700 can convert the capacitance of the object to be tested according to the relationship of the voltage to time. The value is then passed to the pointer current converted by the digit/analog converter 1130 to the drive pointer 950. When the frequency measurement is performed, the frequency operation circuit 1120 captures the signal period, calculates the value of the period, and transmits the period value to the controller 700. The controller 700 converts the period value into a frequency value, and the value is transmitted to the digit. The analog converter 1130 converts to a current that drives the pointer 950 to deflect.

In various measurement modes, the value transmitted by the controller 700 to the digital/analog converter 1130 sets an upper limit. Even if the input signal is large, the value transmitted to the digital/analog converter 1130 is at most the upper limit (maximum pointer current). By limiting the current driving the pointer 950, the pointer can be protected from being burned.

During the measurement process, if the comparison circuit 1000 detects that the potential of the input analog/digital converter 600 is abnormally large, the HV signal is sent to the controller 700, and the controller 700 will prompt the buzzer 1107 to sound. LED1105 is illuminated to alert the user to further enhance the safety of use.

Hereinafter, each block and execution steps of the present invention will be described in detail.

First, FIG. 2 is a functional block diagram used in a pointer meter according to a preferred embodiment of the present invention, and the user selects the electric power of the object to be tested that is considered to be measured by the dial switch 100. The input terminal 200 in the pointer meter is electrically coupled (or connected) to the object to be tested. At this time, the protection circuit 300 transmits a selected set of mode switches (DC voltage, AC voltage, and resistance) through the turntable switch 100. (Ohm), DC current, AC current, frequency, capacitance, etc., forming a circuit conduction with the input terminal 200. The voltage divider 400 and the voltage converter 500 provide a corresponding input voltage to the analog/digital converter 600 according to the voltage value of the input terminal, and then transmit to the controller 700. After the corresponding input voltage is divided, it does not exceed the analog/digital converter 600 full scale voltage value so that it can be processed by the analog/digital converter 600 to produce a value. Passing the signal source 900 to the sense end of the protection circuit 300 to the electronic switch 800 is the corresponding input potential in some passive component measurement mode, which is transmitted to the analog/digital converter 600 and can also be converted to a value. Then, the aforementioned value is converted into a pointer current via the digital/analog converter 1130, and then the pointer 950 is driven to rotate, and the user can read the value corresponding to the pointer 950. If an abnormal voltage is detected, the LED 1105 or the buzzer 1107 may be alerted, or the pointer 950 may be turned to the bottom to remind the user. The above is an operation mode according to a preferred embodiment of the present invention for measuring an object to be tested, and how to detect whether the object to be tested has a mode exceeding that the meter is selected for measurement. When setting the limit voltage value to be processed, the operation principle is as follows.

In a preferred embodiment of the present invention, a set of comparison circuits 1000 is used to detect the voltage level of the voltage dividing point (ie, at the output of the rotary switch 100), and the comparison reference potential can be based on the analog/digital converter 600. The full scale voltage value is set, and a value larger than the full scale voltage value is taken as the reference potential for comparison. For example, if the full scale voltage value is 1 volt, the absolute value of the comparison reference potential can be taken as the largest value, for example, 1.5 volts. When the absolute value of the potential of the voltage dividing point is greater than 1.5 volts, the comparison circuit 1000 outputs the signal HV to a high potential, and the high potential causes the controller 700 to enable the warning device 1100 to alert the user to let the user know at this time. The voltage at the input has exceeded the limit that the system can handle.

In a preferred embodiment of the present invention, the alerting device 1100 can include an LED 1105 and a buzzer 1107. Because the pointer meter of a preferred embodiment of the present invention can determine whether the object to be tested has more than the current multi-function meter is selected to perform the measurement mode within a very short time (less than one millisecond) after contacting the object to be tested. The highest voltage value to be processed, if any, immediately alerts the user to various warnings and causes the pointer 950 to go to the bottom. Therefore, the multi-function pointer meter according to the preferred embodiment of the present invention does not have the potential danger of the conventional pointer meter in use. In Fig. 2, the novel multi-function pointer meter is applied to a pointer meter using the technique of a digital meter. In a preferred embodiment of the present invention, the comparison circuit 1000 and the warning device 1100 are used to achieve the warning function of the present invention.

The following description will be further described in FIG. 3, in which the circuit components (such as resistors, capacitors, diodes, etc., circuit elements and devices) and their connections are only used to illustrate one of the novelties. For the purposes of the preferred embodiment, the manner of implementation of the present invention is not limited to those disclosed in the drawings.

As shown in Fig. 3, (the first input terminal INPUT1/the second input terminal INPUT2/COM corresponds to the input terminal 200 of Fig. 2, and R1~R4/D1/D2/F1/F2 correspond to the protection of Fig. 2 Circuit 300, wherein F1 and F2 are fuses, switches SW1~SW2 correspond to turntable switch 100 of FIG. 2, Rd1~Rd4 correspond to voltage divider 400 of FIG. 2, and Rt1 and Rt2 correspond to voltage converter of FIG. 500. Among them, the voltage/frequency/resistor/capacitor is input using the first input terminal INPUT1, and the current measurement (A) is input using the input terminal second input terminal INPUT2.

In order to save the volume and cost of the circuit, circuits for realizing part of the functions may be constructed by integrated circuits. In this embodiment, the circuits may include: controller 700, analog/digital conversion The converter 600, the electronic switch 800, the signal source circuit 900, the comparison circuit 1000, the digital/analog converter 1130, and the frequency operation circuit 1120 can be fabricated by the same integrated circuit (IC) 1150, as shown in FIG. The components contained in the dashed box.

Referring to FIG. 3, when one embodiment of the multi-function pointer meter with high voltage protection and warning according to the present invention performs the voltage measurement of the object to be tested, the signal to be tested on the object to be tested is input from the first input end. The INPUT1 input, the switches SW1 and SW2 are all turned off (OFF), and the voltage signal is input via the resistor R1. Since the general voltage signal size easily exceeds the range that the analog/digital converter 600 can handle, the input signal needs to be divided first. In the electric meter, the voltage division ratio commonly used for voltage measurement is 1/10, 1/100, 1/1000, and 1/10000, and the potential after voltage division must be lower than the full scale of the analog/digital converter 600. Otherwise, it will exceed the measurable range, and its converted value will deflect the pointer 950 to the end.

In the voltage measurement mode, the controller 700 selects an appropriate voltage dividing resistor from the voltage dividing resistor Rd1-Rd4 of the voltage divider 400 through the electronic switch 800 to connect to R1 to generate an appropriate divided voltage at the n2 node. Thereafter, the potential of the n2 node is further transmitted to the analog/digital converter 600 by switching of the electronic switch 800 to be converted into a numerical value. A part of the circuit diagram of an embodiment of the present invention is shown in Figs. 4A and 4B, and the above operation will be further described. When the voltage measurement is performed, the controller 700 drives one of the electronic switches 800 (including the switches SW3-SW7), for example, the switch SW3 is turned ON. At this time, the partial voltage of the original signal 1/10 is obtained at the node n2. The controller 700 further drives the switch SW7 to be turned on. At this time, the potential of the n2 node becomes 1/10 of the input signal due to the ratio of the resistance.

In the above example of measuring the voltage, the general operation is as follows: if the full scale of the analog/digital converter 600 is 1V, and the input signal to be tested is a 200V signal, At the beginning, the range of measurement is set at the lowest gear position. At this time, the partial pressure ratio is 1/10, and the potential of the n2 node after this partial pressure is 20V. Since 20V exceeds the full scale 1V of the analog/digital converter 600, the converted value will be OL, and the controller 700 will drive the measured gear up one gear. At this time, the controller 700 also controls the electronic switch 800 to switch, and turns off the switch SW7 originally connected to R1 and Rd1 in FIG. 4A, and turns on the switch SW4 connected to R1 and Rd2, so that the voltage division of the gear position is made. The ratio becomes 1/100, and the potential of the input analog/digital converter is reduced to 2V. At this time, the input signal to be tested is 2V at the corresponding input node n2, which still exceeds the full scale 1V of the analog/digital converter 600, so it must jump up one step. At this time, the controller 700 will control the electronic switch 800 to switch again, turn off the SW6 (OFF), and turn on the SW4 (ON), and divide the signal into the original 1/1000 to generate a signal of 200 mV. At this time, the input signal to be tested is lower than the full scale 1V of the analog/digital converter 600 at the potential 200mV of the corresponding input node n2. At this time, the potential is sent to the analog/digital converter 600 for conversion, and a correct one is obtained. The value. Although the conventional electric meter has the function of automatically shifting the file to select the appropriate voltage dividing resistor, the most important thing is that the user must select the measuring mode to be performed by the button or the turntable on the electric meter to be the DC voltage or the AC voltage. . If the user selects the wrong measurement mode, for example, the AC voltage mode is selected on the meter for measurement, but the user does not know that the object to be measured is actually a DC voltage signal with +200V, the measurement result is displayed. It may be a value close to zero, leaving the user to ignore the potential danger. If the user thinks that the object to be tested has no voltage and touches it, it may be electrically injured.

The shortcomings of the above conventional electric meter do not occur in the present invention, because in the present invention, a set of comparison circuit 1000 is used to detect the signal size (voltage level) of the voltage dividing point (corresponding input node) n2-n6, It is compared with the comparison reference potential. Compare the reference potential according to the desired The voltage value of the full scale of the analog/digital converter 600 is set and a set of values larger than the absolute value of the voltage value is taken. For example, if the full scale voltage value is 1V, then two comparators can be used, and the comparison potentials are set at +1.5V and -1.5V, respectively, if the voltage at the voltage divider is higher than + 1.5V, or less than -1.5V. In other words, if the absolute value of the potential of the voltage dividing point (corresponding input node) is greater than 1.5, the output signal of the comparison circuit 1000, that is, HV, will become a high logic level (Logic High), and the signal of this state is sent to the control. After the device 700, please refer to FIG. 3, and the alert device 1100 is enabled. In other words, when the HV signal is High, the controller 700 will drive the buzzer 1107 to sing and illuminate the LED 1105.

The manner in which the voltage measurement is actually performed in the portion shown in Figs. 4A and 4B in an embodiment of the present invention will be further described. When voltage measurement is performed, the controller 700 transmits a set of comparison reference potentials to the comparison circuit 1000, which in this example is +1.5V and -1.5V (absolute value 1.5). In the voltage measurement mode, if the voltage of the object to be tested is +200V, in other words, the input signal is a DC voltage of +200V, but the user misuses the AC voltage mode for measurement, and the measured value is close. Zero, because the value close to zero does not have OL (Overload), the controller 700 does not drive the gear to jump up, the range of measurement will stop at the lowest gear, and the partial pressure ratio of the lowest gear is 1 /10, at this time, the corresponding voltage dividing point (n2 node) is a 20V DC voltage signal. The absolute value of this potential (20V) is higher than the comparison potential of +1.5V (absolute value 1.5). At this time, the first comparator The output of CMP1 will become High, further causing the HV signal to become High, and the HV signal is sent back to the controller 700 (Fig. 4). The controller 700 will drive the buzzer 1107 to sing and illuminate the LED 1105, thus Achieve the effect of warning.

Briefly, in accordance with a preferred embodiment of FIG. 4A, the comparison circuit 1000 includes a window comparator (including a first comparator CMP1 and a second comparator CMP2) and a logic OR gate. The non-inverting input terminal of the first comparator CMP1 is electrically coupled to the inverting input terminal of the second comparator CMP2, and the inverting input terminal of the first comparator CMP1 is fed to be selected for the current meter to be performed. The measured mode is preset to have a positive value of +1.5V (ie, the upper threshold voltage) of the highest voltage value to be processed (eg, 1.5V); and the non-inverting input of the second comparator CMP2 is fed The pointer meter is selected to be measured in a mode that is preset to a negative value of -1.5V (ie, the lower threshold voltage) of the highest voltage value (eg, 1.5V) to be processed. When the absolute value of the voltage transmitted to the input terminal of the window type comparator is smaller than the absolute value of the highest voltage to be processed preset by the mode to be measured, the first comparator CMP1 and the second comparator CMP2 will both be Is negative saturation, in other words, the output will be low logic level (L), so the two inputs of the logic OR gate OR are low logic level (L), so the output signal HV of the logic or gate OR is low logic. Level (L).

When the absolute value of the voltage transmitted to the input terminal of the window type comparator in the comparison circuit 1000 is greater than the absolute value of the highest voltage to be processed preset by the mode to be measured, the first comparator CMP1 and the second At least one of the comparators CMP2 will be positively saturated. In other words, at least one of the outputs is a high logic level (H), so at least one of the two inputs of the logic OR gate OR is a high logic level (H), so the output signal HV of the logic OR gate OR is a high logic Bit (H). When the HV is at a high logic level (H), please refer to FIG. 3, and the controller 700 enables the buzzer 1107 and/or the light-emitting diode 1105 to alert the user.

In other words, since the window type comparator has the window type range limiting characteristic, it can be detected that when the value of the direct current voltage and the alternating current voltage exceeds the threshold voltage value (the upper threshold voltage and the lower threshold voltage) which can be processed by the pointer meter, A signal with a high logic level can be generated by the window comparator. Therefore, the technical problem that the AC voltage cannot be measured too high in the DC voltage position or the DC voltage is too high in the AC voltage position has been solved.

Next, in accordance with a preferred embodiment of FIG. 4B, the comparison circuit 1000 includes a window comparator (including a first comparator CMP1 and a second comparator CMP2) and two diodes D3, D4. Comparing with FIG. 4A, it can be found that the embodiment of FIG. 4B uses diodes D3 and D4 as output terminals of the output signal HV. When the absolute value of the voltage transmitted to the input terminal of the window type comparator in the comparison circuit 1000 is greater than the absolute value of the highest voltage to be processed preset by the mode to be measured, the first comparator CMP1 and the second At least one of the comparators CMP2 will be positively saturated. In other words, at least one of the outputs is a high logic level (H), so at least one of the two inputs of the diode D3 or the diode D4 is a high logic level (H), so the final output signal HV is high. High Voltage Level (HVL).

4A and 4B illustrate an embodiment of the two operating window comparators of the present invention, the final output of which may be a high logic level or a high voltage level. However, it is known to those of ordinary skill in the art that high voltage level or high logic level is not the only choice as a high voltage prompt signal. Changing the high logic level to a low logic level through the inverter can also be used as The high voltage prompt signal of the controller 700; similarly, after converting the high voltage level to the low voltage level, the high voltage prompt signal of the controller is also accepted by the new multi-function pointer meter. In other words, the type of voltage level or logic level is not intended to limit the present invention.

The following describes a pointer meter according to a preferred embodiment of the present invention when the object to be tested is a passive component (resistance/capacitance), and how the operation mode is such that the potential of the object to be tested exceeds that of the meter. When the limit voltage value to be processed is preset by the mode to be measured, the user can be automatically alerted. Please continue to refer to Figure 4A. When performing passive component (resistance/capacitance) measurement, the object to be tested is input by the first input terminal INPUT1. In the passive component measurement mode, the corresponding input nodes are n3 and n4, and node n3 is On the force side, node n4 is the sense end. When proceeding During measurement, the signal source circuit 900 applies a voltage or current to the object to be tested through a thermistor (Positive Temperature Coefficient Resistor: PTC) R3, and R2 is a resistor for protecting the integrated circuit. In the design of the circuit, the current does not flow through the resistor R2, so the potential of the n4 node is equal to the potential on the object to be tested, and the comparison circuit 1000 detects the potential of the object to be tested through the node n4, if an abnormal voltage is detected. When the absolute value of the potential value of the corresponding input node n4 is greater than 1.5, the HV signal will become High. At this time, the controller 700 will drive the buzzer 1107 to sing and illuminate the LED 1105, so that the warning effect can be achieved.

When an embodiment of the multi-function pointer meter with high voltage protection and warning according to the present invention performs measurement of the resistance of the object to be tested, please refer to FIG. 5A, in which the first operational amplifier OP1 and P-type gold-oxygen half-field The transistor PMOS1, source resistor Rs1, which are part of the signal source circuit 900, constitute a typical current source circuit. Among them, changing the size of the source resistance Rs1 can change the output size of the current source to respond to different resistance measurement ranges. The current source flows through the source resistor R3 and the resistor R* to be tested, and generates a potential on the resistor R* to be tested, the n4 node is the detecting end, and the potential of the n4 node is equal to the potential on the object to be tested. In this embodiment, that is, the potential of the corresponding input node, and the potential value is transmitted to the analog/digital converter 600 by the electronic switch 800, the voltage value on the object R* can be obtained. The controller 700 divides the voltage value by the magnitude of the current source to convert the resistance value of the object R*, and the controller 700 calculates the value of the current to be measured, and then transmits the value to the digital/analog converter 1130. After being converted to the pointer current, the pointer 950 is driven to rotate.

The above is an electric meter according to a preferred embodiment of the present invention for measuring the operation mode of the object to be tested as a resistor, and how to detect whether the object to be tested has a mode exceeding that the meter is selected for measurement. When setting the limit voltage value to be processed, the operating principle is as follows Description: In this mode, if a potential of +1V is applied to the positive input of OP1, the potential of the n10 node will be very close to +1V due to the negative feedback of the OP. If the potential of the n9 node is +3V and the resistance of Rs1 is 200K ohms, then the current of the current source is 10uA. In the normal measurement state, the potential on the object to be tested should be a positive value, and the maximum should not exceed the potential of the current source, +1V, and the minimum is close to 0V. According to the pointer meter of a preferred embodiment of the present invention, in the resistance measurement mode, the controller 700 drives the switch in the comparison circuit 1000 to switch, and the comparator in the comparison circuit 1000 detects the potential of the n4 node. Whether it is abnormal, if the potential of the n4 node is higher than the potential of the current source, or much lower than 0V, it is regarded as abnormal, which means that the probe at the input end of this time may touch an abnormal voltage. In other words, the electrical property of the object R* electrically coupled at the input end has exceeded the highest voltage value to be processed by the mode in which the pointer is selected for measurement. In the example given in Figure 5A, the comparison potential is +1.5V and -1.5V. If the potential of the n4 node is higher than +1.5V or lower than -1.5V, in other words, if the absolute value is greater than 1.5, the HV signal will change. If it is High, the controller 700 starts the warning mechanism according to the output signal of the comparison circuit 1000 being a high logic level.

When an embodiment of the multi-function pointer meter with high voltage protection and warning according to the present invention performs measurement of the capacitance of the object to be tested, please refer to FIG. 5B, the current source flows through the resistor R3 and the capacitor C* to be tested. The capacitance potential gradually increases as the current flows in. This potential is transmitted to the analog/digital converter 600 via the electronic switch 800 (Fig. 3), and the controller 700 converts the capacitance value of the object C* according to the change in potential versus time, and then the controller 700 After the value is transferred to the digit/analog converter 1130 for conversion to the pointer current, the pointer 950 is driven to rotate.

The above is an electric meter according to a preferred embodiment of the present invention for measuring the operation mode of the object to be tested as a capacitor, and how to detect whether the object to be tested has a mode exceeding that the meter is selected for measurement. When setting the limit voltage value to be processed, the operating principle is as follows In this mode, in the capacitance measurement mode, the controller 700 drives the switch in the comparison circuit 1000 to switch. At this time, the comparator in the comparison circuit 1000 will detect whether the potential of the n4 node is abnormal, if the n4 node The potential is higher than the current source's potential, or much lower than 0V, it is considered abnormal, which means that the probe at the input end may touch an abnormal voltage. In other words, the electrical property of the object C* electrically coupled at the input end has exceeded the highest voltage value to be processed by the mode in which the meter is selected for measurement, which means that the probe at the input end may touch. To a voltage source, or an abnormal potential on the capacitor. In the example given in Figure 5B, the comparison potential is +1.5V and -1.5V. If the potential of the n4 node is higher than +1.5V or lower than -1.5V, the HV signal will become High. The 700 will activate the alert mechanism according to the high logic level of the output signal of the comparison circuit 1000.

When performing the frequency measurement of the signal on the object to be tested according to an embodiment of the multi-function pointer meter with high voltage protection and warning according to the present invention, please refer to FIG. 3, the signal to be tested is input by INPUT1, and the switch SW1 is ON, the switch SW2 is OFF, and the comparison circuit 1000 in this measurement mode mainly detects whether the potential of the resistor R5 is abnormal. The diodes D1 and D2 are both OFF during normal measurement. At this time, since there is no current on R5, there is no voltage difference between the n5 node and the ground, so the voltage is equal to 0V. When the first input terminal INPUT1 inputs a large positive voltage, the diode D2 will break down, and the diode D1 will also be turned on. At this time, the resistor R5 will flow current so that the corresponding input node n5 generates a positive Voltage; when the first input terminal INPUT1 inputs a large negative voltage, the diode D1 will generate a break down, and the diode D2 will also be turned on. At this time, the resistor R6 will flow current so that the corresponding input node n5 produces a negative Voltage.

And in a measurement mode according to a preferred embodiment of the present invention, detecting whether the object to be tested has a pole that is preset to be processed in a mode in which the meter is selected to be measured. When the voltage limit is limited, the operation principle is as follows: In this mode, in the frequency measurement mode, the controller 700 drives the switch in the comparison circuit 1000 to switch, and the comparator in the comparison circuit 1000 detects Whether the potential of the corresponding input node n5 is abnormal, for example, higher than +1.5V or lower than -1.5V, in other words, when the absolute value is greater than 1.5, it is regarded as abnormal. At this time, the HV signal becomes High, and the controller 700 compares according to the comparison. The output signal of the circuit 1000 is at a high logic level to activate the alert device 1100.

When performing the current measurement on the object to be tested according to an embodiment of the multi-function pointer meter with high voltage protection and warning according to the present invention, please refer to FIG. 3, and the signal to be tested is input by the second input terminal INPUT2. R4 is a resistor for protecting the IC, and node n6 connected to R4 is a detecting end, and is also a corresponding input node when performing current measurement. The current signal to be tested flows through the fuse F1 and the resistor Rt1, and the current is converted into a voltage signal at Rt1, and the voltage is transmitted to the electronic switch 800 through the node n6, and then the potential is transmitted to the analog/digital conversion through the electronic switch 800. The converter 600 can convert the value of this voltage. This value is transmitted to the controller 700. The controller 700 divides the voltage value by the magnitude of Rt1 to convert the value of the current to be measured, and then transfers the value to the digital/analog converter 1130 to convert it to the pointer current, and then drives the pointer. 950 turns.

The above is an electric meter according to a preferred embodiment of the present invention for measuring the operation mode of the current, and how to detect whether the object to be tested has a limit which is preset to be exceeded in a mode in which the meter is selected for measurement. When the voltage value is used, the operation principle is as follows: In this mode, the controller 700 drives the switch in the comparison circuit 1000 to switch, and the comparator in the comparison circuit 1000 detects the n6 node, that is, correspondingly Whether the potential on the voltage input node n6 of the measurement mode is abnormal, for example, higher than the comparison reference potential of the comparator in the comparison circuit 1000 (+1.5 V) or lower than the comparison reference potential of the comparator in the comparison circuit 1000 (-1.5) V), in other words, when the absolute value of the potential on the corresponding input node n6 is greater than the preset value of 1.5V (the aforementioned preset value is the comparison circuit 1000) If the comparator compares the absolute value of the reference potential, it is regarded as an abnormality. If this situation occurs, if there is no abnormally large current, the user will misuse the current mode and take the voltage. The HV signal becomes High, and the controller 700 activates the alerting device 1100 according to the output signal of the comparison circuit 1000 being a high logic level.

The above embodiments cover the measurement function of the general pointer meter and the measurement function of the partial digital meter, and the preferred embodiment of the present invention can be applied, so that the pointer meter can be used in any measurement mode. With high voltage automatic warning function. Therefore, as long as it is possible to cause damage to the meter, or a dangerous situation, the user can be warned in various ways, which can improve the safety of the measurement and prolong the service life of the pointer meter.

Obviously, many modifications of the present invention are possible in accordance with the description in the above embodiments to cause small differences. It is therefore to be understood that within the scope of the appended claims, the invention may be The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention; any equivalent changes or modifications made without departing from the spirit of the present invention should be included in the following patent application. Within the scope. Although the foregoing has been described in some embodiments of the present invention with a certain degree of specificity or reference to more than one embodiment, those skilled in the art may circumvent the components or circuit connections mentioned in the foregoing embodiments. Means, instead of other modifications that are less important components or circuit connections, are intended to fall within the scope of the following claims.

100‧‧‧ Turntable switch

200‧‧‧ input

300‧‧‧Protection circuit

400‧‧ ‧ voltage divider

500‧‧‧Voltage conversion circuit

600‧‧‧ analog/digital converter

700‧‧‧ Controller

800‧‧‧Electronic switch

900‧‧‧Signal source circuit

950‧‧ pointer

1000‧‧‧Comparative circuit

1100‧‧‧ Warning device

1105‧‧‧LED

1106‧‧‧Auditory warning device

1107‧‧‧Tactile warning device

1120‧‧‧frequency operation circuit

1130‧‧‧Digital/analog converter

Claims (10)

A multi-function pointer electric meter with high voltage protection and warning, when a user electrically couples one of the plurality of input terminals of the multi-function pointer electric meter with high voltage protection and warning to an object to be tested, When the absolute value of a potential of the object to be tested exceeds the absolute value of a preset limit value, a warning is generated to remind the user to include: a pointer meter is used according to a measurement mode selected by the user, correspondingly a turntable switch is coupled to feed the electrical property of the object to be tested through the input end, and is divided by an electronic switch and a voltage divider to obtain a corresponding input potential, which is fed into an analog/digital converter for processing. A controller calculates a value, and the controller controls a digit/analog converter to convert to a pointer current according to the value, and rotates a pointer, and the controller presets a maximum pointer current, and when the value is converted When the pointer current is greater than the maximum pointer current, outputting the maximum pointer current; and a comparison circuit for using the absolute value of the corresponding input potential and the preset limit value The value comparison generates a high voltage prompt signal when the absolute value of the corresponding input potential is greater than the absolute value of the preset limit value, and the absolute value of the preset limit value is greater than the full scale of the analog/digital converter ( Full Scale) The absolute value of the voltage value is still large; A warning device, when the controller receives the high voltage prompt signal, enables the warning device to alert the user. The multi-function pointer meter with high voltage protection and warning according to claim 1, wherein the comparison circuit comprises: at least one comparator electrically coupled to the electronic switch to obtain the corresponding input potential, Comparing with the absolute value of the preset limit value; and a logic gate electrically coupled to the output of the comparator to generate the high voltage prompt signal, only if the absolute value of the corresponding input potential is greater than the preset limit value The high voltage prompt signal is generated when the absolute value is reached. The multi-function pointer electric meter with high voltage protection and warning according to claim 2, wherein the comparator comprises at least a window type comparator, wherein an absolute value of the corresponding input potential is greater than an absolute value of the preset limit value At the time of the value, at least one of the two outputs of the window comparator exhibits a high logic level. A multi-function pointer meter with high voltage protection and warning as described in claim 2, wherein the logic gate is a logic or gate, which is used to receive the output of the comparator and at the corresponding input potential When the absolute value is greater than the absolute value of the preset limit value, The output of the comparator has at least one high logic level, and outputs the high voltage prompt signal of the high logic level. The automatic warning meter according to claim 1, wherein the automatic warning meter further comprises: a protection circuit, a signal source circuit and a frequency operation circuit, wherein the signal source circuit is used for the user to select the measurement. When the mode is a resistance measurement mode or a capacitance measurement mode, it is used as a current source to correspondingly generate the corresponding input potential through the protection circuit, the electronic switch, the signal source circuit, the comparison circuit, The digital/analog converter, the analog/digital converter, the controller, and the frequency operation circuit are fabricated in the form of an integrated circuit. The multi-function pointer electric meter with high voltage protection and warning as described in claim 1, wherein the warning device is selected from the group consisting of: an LED and a buzzer. A multi-function pointer electric meter with high voltage protection and warning, when a user electrically couples one of the plurality of input terminals of the multi-function pointer electric meter with high voltage protection and warning to an object to be tested, When the absolute value of a potential of the object to be tested exceeds the absolute value of a preset limit value, a warning is generated to remind the user that the pointer includes: a pointer meter used for measuring according to the user's selection. a mode, wherein a corresponding turntable switch is used to couple the electrical property of the object to be tested through the input end, and a corresponding input potential is obtained by dividing an electronic switch and a voltage divider to feed an analog/digital converter. After processing, a value is calculated by a controller, and the controller controls a digit/analog converter to convert to a pointer current according to the value, and rotates a pointer, and the controller presets a maximum pointer current. And outputting the maximum pointer current when the pointer current is greater than the maximum pointer current; and a comparison circuit for comparing the absolute value of the corresponding input potential with the absolute value of the preset limit value, in the corresponding When the absolute value of the input potential is greater than the absolute value of the preset limit value, a high voltage prompt signal is generated, and the absolute value of the preset limit value is greater than the full scale (Full Scale) voltage value of the analog/digital converter. The absolute value is also a large value, and the comparison circuit includes at least one window type comparator, and the positive value of the preset limit value is used as an upper threshold voltage, and the negative value of the preset limit value is used as a a voltage, when the corresponding input potential is greater than the upper threshold voltage or less than the lower threshold voltage, that is, the absolute value of the corresponding input potential is greater than the absolute value of the preset limit value, and the two outputs of the window type comparator are at least One will generate the high voltage prompt signal; and a warning device, the controller receives the high voltage prompt signal Enable the alert device to alert the user. The multi-function pointer electric meter with high voltage protection and warning as described in claim 7 of the patent application, wherein the automatic warning electric meter further comprises: a protection circuit, a signal source circuit and a frequency operation circuit, the signal source circuit system When the user selects the measurement mode as a resistance measurement mode or a capacitance measurement mode, as a current source, the corresponding input potential is correspondingly generated through the protection circuit, the electronic switch, the signal The source circuit, the comparison circuit, the digital/analog converter, the analog/digital converter, the controller, and the frequency operation circuit are fabricated in the form of an integrated circuit. The multi-function pointer electric meter with high voltage protection and warning according to claim 7 of the patent application, wherein the warning device is selected from the group consisting of: an LED and a buzzer. The multi-function pointer meter with high voltage protection and warning according to claim 7 of the patent application, wherein the high voltage prompt signal is the high voltage prompt signal of the high logic level or the high voltage level of the high logic level.