KR20150038874A - Circuit for Detecting Capacitor and Part Probe Station Using the Same - Google Patents

Abstract

The present invention relates to a circuit for detecting a capacitor and a part probe station using the same that can be implemented in a detection equipment for detecting a low-Farad capacitor used in a peripheral circuit for a mobile phone antenna. The capacitor detecting circuit supplies a square wave to one terminal of a specific capacitor in an antenna peripheral circuit, and determines if the capacitor is properly mounted by measuring a voltage across a resistor connected between the other terminal of the capacitor and the ground as a test point voltage. Here, the capacitance of the capacitor is 1pF to 10pF; the resistance of the resistor is 1MΩ or more; and the resistance of the resistor should be as large as possible in order to increase the test point voltage.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor detecting circuit,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a basic circuit development and a component tester for detecting the presence or absence of mounting of a low capacitance capacitor on a circuit board and in particular to a capacitor applicable to an inspection apparatus for detecting a low capacitance capacitor used in an antenna peripheral circuit of a cellular phone A detection circuit and a component tester using the same.

An antenna is a device that converts electric signals represented by voltage and current and electromagnetic waves represented by an electric field and a magnetic field. The antenna senses the electromagnetic wave signal floating in the free space by the interaction of the external electromagnetic field and the electric signal on the antenna wire, and the electronic device senses the electric signal in the electronic device and resonates at a specific frequency to emit electromagnetic waves in the free space. These antennas are mounted on the products together with the antenna peripheral circuits.

In recent years, demand for peripheral circuits for antennas has increased rapidly due to the spread of mobile terminals such as smart phones, and as the demand for peripheral circuits for antennas has increased, reliability and efficiency of performance and quality inspection of circuit boards having peripheral circuits for antennas Is emerging. In this environment, there is a demand for an efficient component inspection method for a component such as a circuit board or a component assembly on which an antenna peripheral circuit is mounted.

The present invention provides a capacitor detection circuit and a component checker using the same that can efficiently and reliably inspect whether a low capacitance capacitor is mounted on a circuit board mounted with an antenna peripheral circuit.

According to an aspect of the present invention, there is provided a capacitor detection circuit including: a square wave is applied to one terminal of a specific capacitor in an antenna peripheral circuit, and a voltage between both terminals of the resistor connected between the other terminal of the capacitor and the ground Is detected as the voltage of the measurement point to determine whether or not the capacitor is mounted.

In one embodiment, the capacitor is a low capacitance capacitor having a capacitance of 1 kV to 10 kV, and the resistance of the resistor is 1 M or more. Here, the resistance value of the resistor can be set as large as possible in order to increase the voltage at the measuring point.

In one embodiment, the rising and falling edges of the square wave are set to be close to a right angle. That is, the change amount of the unit time in the rising edge interval and the falling edge interval of the square wave can be set to be closest to a value converging on zero (0).

In one embodiment, the capacitor detection circuit further includes a switch provided between the one terminal of the capacitor and the rectangular wave generating portion generating the rectangular wave. Here, the switch performs a noise blocking operation to prevent the noise from the square wave generating unit from affecting the capacitor in the OFF state after the initial setting operation.

A component inspecting apparatus according to an aspect of the present invention includes a square wave generating unit for applying a square wave to one terminal of a specific capacitor in an antenna peripheral circuit, a resistor connected between the other terminal of the capacitor and the ground, A second amplifier for amplifying an output signal of the first low-pass filter, a second amplifier for amplifying an output signal of the second amplifier, and a second amplifier for amplifying an output signal of the second low- And a central processing unit for detecting an output signal of the second low-pass filter.

In one embodiment, the component tester further includes a switch block having a rectangular wave generating unit and a switch provided between the one end of the capacitor and the rectangular wave generating unit to block noise inside and outside the housing of the component tester on which the power supply is mounted . Here, the switch may be provided with an analog switch or a relay, which injects or momentarily disconnects a signal of a connection cable connected to one terminal of the capacitor.

In one embodiment, the component inspecting apparatus further comprises a first shielding portion for shielding at least one of the power supply device, the square wave generating portion, and the switching power supply device for controlling and supplying the power to the switch block, The upper portion of the housing where the circuit board including the antenna peripheral circuit is disposed is provided with the member having the metallic second shielding portion. Or, depending on the implementation, the component tester may comprise a first shield and a second shield.

According to the present invention, it is possible to provide a capacitor detection circuit capable of efficiently and reliably inspecting whether or not a low-capacitance capacitor is mounted on a circuit board on which an antenna peripheral circuit is mounted using a square wave, and a component tester using the same.

Also, according to the present invention, it is possible to provide a capacitor detecting apparatus capable of detecting whether or not a capacitor is mounted at an inexpensive price of about 1/10 as compared with an impedance analyzer most similar to an impedance analyzer, and a component inspector using the same.

In addition, according to the present invention, there is provided a capacitor detection circuit and a component inspecting device that can be utilized not only for efficiently detecting the mounting of specific components in a smartphone antenna peripheral circuit but also capable of creating high added value through a mass production facility using the same .

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram for explaining a capacitor current according to a switch operation in a general capacitor circuit; FIG.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a capacitor detection circuit, and more particularly to a capacitor detection circuit.
3 is a waveform diagram showing a square wave Vi applied to a capacitor input terminal A and a voltage Vo at a measurement point B when the switch is turned on and off in Fig.
4 is a diagram illustrating an example of a general antenna peripheral circuit applied to a smartphone;
5 and 6 are waveform diagrams for determining whether a capacitor is mounted by connecting a capacitor detection circuit of the operating principle shown in FIG. 2 to a circuit board including an antenna peripheral circuit as shown in FIG.
7 is a schematic circuit diagram of a capacitor detection circuit according to an embodiment of the present invention;
FIG. 8 is a schematic waveform diagram of a square wave of the rectangular wave generating section of FIG. 7; FIG.
Figure 9 is a schematic perspective view of a part tester according to an embodiment of the present invention;

The following terms are defined in consideration of the functions of the present invention, and this may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

In explaining the present invention, the inventor of the present invention uses a square wave to derive a measure for detecting the presence or absence of mounting of a low-capacitance capacitor on a circuit board. The detection technique of the capacitor mounting using such a square wave is based on knowledge of the basic circuit knowledge about the capacitor component and the conversion to the frequency axis (Fourier transform, etc.) of various waveforms such as a sine wave and a square wave expressed in the time axis, The invention is possible through the detailed description provided.

In addition, the present invention provides an electrical and mechanical noise reduction method for external noise in the process of mounting a capacitor detection circuit on an actual component inspection equipment in determining whether to mount a low capacitance capacitor.

The same component inspection equipment as the low capacity capacitor detection method described in the present invention has not been manufactured or reported yet and it is about 1/10 times lower than a conventional component inspection unit for detecting a low capacitance capacitor by another principle It can be implemented.

Thus, in the present invention, based on basic circuit knowledge and experience, a detection circuit for detecting whether a low-capacitance capacitor is mounted using a square wave, a method for implementing a component inspection apparatus based on the detection circuit, And provides a method for facilitating capacitor detection.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a diagram for explaining a capacitor current according to a switch operation in a general capacitor circuit.

Referring to FIG. 1, a current (i _C ) flowing in a capacitor circuit is expressed by the following Equations (1) to (4).

In Equation (1), q is charge, dq is the amount of charge change, t is time, and dt is unit time. That is, the current (i _C ) refers to the amount of change in charge that occurs over time.

In Equation (2), Q refers to the amount of charge that can be stored in the capacitor, C refers to the capacitance or capacitance, and V refers to the voltage applied across the capacitor.

Equation 2 is substituted into Equation 1 and summarized as Equation 3 and Equation 4 below. In Equation (3), the capacitance change (dC) is zero.

If dt is converged to zero in the equation (4), that is, when the infinitely short on / off (On / Off) of the time switch, the current (i _C) flowing in the capacitor is the infinity (∞). This can be expressed by Equation (5).

2 is a circuit diagram for explaining a principle of determining whether a capacitor is mounted on a circuit board in a capacitor detection circuit according to an embodiment of the present invention.

Referring to Fig. 2, the capacitor detection circuit comprises a capacitor, and a resistor R _L connected in series with the capacitor.

The capacitor detection circuit according to the present embodiment is configured to measure the voltage Vo at the common connection point between one terminal of the capacitor and one terminal of the resistor R _L. The common connection point is a measurement point (B) for detecting whether or not the low-capacitance capacitor is mounted in the capacitor detection circuit.

The voltage at the measurement point, that is, the B voltage Vo, can be expressed by the following equation (6).

In Equation 6, the resistor R _L may have various resistance values, for example, 3 M OMEGA. The resistor R _L may have a resistance value as large as possible in order to set the B voltage to a high value.

3 is a waveform diagram showing a square wave Vi having a voltage (hereinafter referred to as A voltage) applied to a capacitor input terminal A when the switch is turned on and off in FIG. 2 and a voltage Vo at the measuring point B to be.

As shown in Fig. 3, the voltage Vo at the measurement point B corresponds to a state transition of the square wave Vi generated in response to the switch operation, ). The voltage peak Vp of the capacitor voltage waveform is smaller than the maximum value of the square wave Vi.

4 is a diagram illustrating an example of a general antenna peripheral circuit applied to a smartphone.

4, an antenna peripheral circuit applied to a conventional smart phone is disposed between an antenna and a central processing unit such as a mobile processing unit (MPU), and includes a terminal 1 (D1 A capacitor 2 connected between the terminal 1 and the terminal 2 and a capacitor 2 connected in parallel between one terminal of the capacitor C _L and the ground, An inductor 1 (L1), and an inductor 2 (L2) connected in parallel between the other terminal of the capacitor and the ground.

The capacitor (C _L ) applied to the antenna peripheral circuit has a very small capacitance of about 1 kV to about 10 kV.

5 and 6 are waveform diagrams for determining whether a capacitor is mounted by connecting a capacitor detection circuit as shown in FIG. 2 to a circuit board including an antenna peripheral circuit as shown in FIG.

5, the capacitor voltage waveform Vo has a voltage peak equal to or larger than the magnitude of the reference voltage Vx, and the low-capacitance capacitor is mounted on the antenna peripheral circuit of the circuit board at the magnitude of the voltage peak Vx It can be judged.

6, the capacitor voltage waveform Vo has a voltage peak that is smaller than the magnitude of the reference voltage Vx, and the low-capacitance capacitor is not mounted on the antenna peripheral circuit of the circuit board .

As described above, when the capacitor detection circuit according to the present embodiment is used, when the capacitor is mounted on the antenna peripheral circuit of the circuit board and when the capacitor is not mounted, the electrical signal size at the measurement point of the capacitor detection circuit is It can be seen that the presence or absence of the low-capacitance capacitor can be easily detected.

On the other hand, since the small signal values (Vx, V'x) are very small, an actual circuit can be processed to be read by a central processing unit (microcomputer, microprocessor, etc.) using an amplification and a low-pass filter.

7 is a schematic circuit diagram of a capacitor detection circuit according to an embodiment of the present invention. 8 is a schematic waveform diagram of a square wave of the rectangular wave generating portion of FIG.

7, the capacitor detection circuit according to the present embodiment is connected to one terminal (see D1) of a low-capacitance capacitor C _L , which is basically assumed to be mounted in the antenna peripheral circuit PA, And a resistor R _L connected in series between the other terminal of the low capacitance capacitor C _L and the ground. Here, the presence or absence of the capacitor is detected by measuring the voltage across the other terminal of the low-capacitance capacitor (C _L ) or between both terminals of the resistor (R _L ) through the predetermined voltage detection means (13).

Any signal must pass through the capacitor to detect the presence of the capacitor, and the low-capacitance capacitor (C _L ) can not pass the signal when the low-frequency is injected because the self-resonant point is high at several hundred MHz. In fact, if a signal of several hundreds MHz is generated and injected into a capacitor, the complexity of the circuit, generation of various kinds of noise, and cost of manufacturing the substrate occur. Therefore, in the present invention, a method of generating several hundreds of MHz signals is implemented by using a square wave. That is, in the present invention, it is noted that the square wave includes all the high frequency components from the low frequency component to several hundreds of MHz in the frequency domain, and a rectangular wave is injected into the capacitor C _{L to} determine whether or not the low-capacitance capacitor is mounted .

The capacitor detection circuit according to this embodiment includes a first amplifier 131 having an input terminal connected to a measurement point B or D2 located adjacent to the other terminal of the low capacitance capacitor C _L , A first low pass filter (LPF) 132 having an input terminal connected to the output terminal of the first amplifier, a second amplifier 133 having an input terminal connected to the output terminal of the first low pass filter, 2 low pass filter 134 and a micro control unit (MCU) having an input terminal connected to the output terminal of the second low pass filter. The input of the central processing unit 135 may be provided by an analog-to-digital converter (ADC).

The square wave generating section 116 generates a square wave having a rising edge which rises as steeply as possible and a falling edge which rises as steep as shown in Fig. 8 (a). This is to set the unit time dt corresponding to the ON or OFF time of the switch close to zero (see Equation 4). With such a configuration it is possible to increase the magnitude of the current (i _c) flowing through the capacitor, to accurately determine the mounting presence or absence of the low-capacity capacitors etc. antenna peripheral circuit for accurately detecting the circuit board a voltage waveform (Vo) of the capacitor thereby .

8B, when the switching time, that is, the unit time dt of the switching time in the rising edge section R or the falling edge section D of the rectangular wave becomes relatively large, the current flowing in the capacitor (i _c ) becomes very small and it is practically impossible to detect the presence or absence of the mounting of the low-capacitance capacitor.

Referring again to Fig. 7, the resistor R _L is set to a resistance value as large as possible so that the peak of the capacitor voltage waveform at the measurement point (see D2) has a large value.

The first amplifier 131 and the second amplifier 133 amplify the small signal at the measurement point and the first low pass filter 132 and the second low pass filter 134 amplify the noise from each amplifier, Remove noise.

The small signal detected at the measurement point is amplified and filtered in two stages by using the first amplifier 131, the first low-pass filter 132, the second amplifier 133 and the second low-pass filter 134, A small signal can be read from the input terminal (ADC) of the central processing unit 135. According to such a configuration, the capacitor detection circuit can precisely detect whether or not the low-capacitance capacitor is mounted even under a certain noise environment.

In addition, by using the two-stage amplification and filtering structure described above, even when the small signal is excessively filtered by the first low-pass filter 132, the signal is distorted even if the small signal is amplified by the second amplifier 133, The confusion can be prevented by discriminating whether or not the capacitor is mounted. However, the output signal of the second amplifier 133 may be filtered again by the second low-pass filter 134 to prevent the confusion.

Actually, the above-mentioned capacitor detection circuit does not exist alone but is connected to other components and exists as one block circuit (component checker). One embodiment of such a component inspector is described below.

9 is a schematic perspective view of a part tester according to an embodiment of the present invention. In Fig. 9, the interior of the housing is shown to be viewed through for convenience of explanation.

9, the component inspecting apparatus according to the present embodiment includes a housing 110, a power supply unit 111, a main board 112, a main board connector 113, a connecting cable 114, a switching power supply unit 116, A square wave generating section 117, a connection connector 121, a switch block 122, a signal disconnection switch 123, and an amplification-filter circuit 125.

The housing 110 may include a lower housing 110a and an upper housing 110b. The upper housing 110b may be provided to cover the upper opening of the lower housing 110a.

The power supply unit 111 receives external power (220 V or the like) and supplies power to each component of the component tester.

The main board 112 is a component for inspecting the performance and quality of a product (such as a circuit board on which an antenna peripheral circuit is mounted) 120 placed on the upper housing 110b or a function corresponding to the means Circuit portion, etc.).

The connector of the product 120 is connected to the main board connector 113 through the connector 121. [ The main board connector 113 and the connection connector 121 are connected to each other by a connection cable 114.

The switching power supply unit 116 controls the operation of a plurality of switches including a signal break switch in the switch block 122 and supplies power to the switch.

The square wave generating unit 117 generates a square wave having a steep rising edge and a steep falling edge and applies the generated square wave to the product 120 or the terminal 1 of the antenna peripheral circuit of the product through the connecting cable 114a .

On the connection connector 121, a switch block 122, a signal disconnection switch 123, and an amplification-filter circuit 125 may be provided.

The switch block 122 operates to couple or disconnect the particular circuitry of the product to and from the particular test circuitry of the main board 112 during performance and quality testing of the product 12. [

The signal disconnect switch 123 operates to disconnect a circuit or cable connected to one terminal of the low capacitance capacitor at least momentarily after applying a square wave to one terminal of the low capacitance capacitor in the antenna peripheral circuit of the product 120.

The amplifier-filter circuit 125 may correspond to a combination of the first amplifier, the first low-pass filter, the second amplifier, and the second low-pass filter mentioned in FIG.

As described above, the component inspecting apparatus 100 according to the present embodiment includes a main board 112 mounted on the lower portion of the housing 110, and a connector 110 connecting the connector of the main board and the connector of the product 120 to be inspected placed on the upper portion of the housing 110 A signal disconnecting switch 123 between one end of the connecting cable and the connector of the product 120, a switching power supply 116 for controlling the signal disconnection switch and supplying driving power, A square wave generator 117 arranged to apply a square wave to one terminal of the low capacitance capacitor in the product, a resistor (see FIG. 7) connected to the other terminal of the low capacitance capacitor, an amplifier-filter circuit 125 And may be configured to include the above-described connection relationship.

In the component inspecting apparatus according to the present embodiment, various noises generated from the power supply unit 111, the main substrate 112, the switching power supply unit 116, etc. are introduced through the connection cable 114 and the like, It is possible to additionally provide the following four configurations selectively or in combination.

First, shielding is performed to completely enclose the power supply unit 111 in the component inspecting apparatus with a metal material, thereby shielding the noise generated from the power supply unit 111 from the source.

Secondly, the surface of the connection cable 114 is shielded by a predetermined shielding portion 115 to prevent external noise from flowing into the signal line in the connection cable 114.

Third, the switch block 122 or the signal break switch 123 is used to electrically disconnect the signal of the connection cable 114 when the capacitor is detected. When the signal of the connection cable 114 is cut off, the noise introduced into the connection cable 114 is completely cut off, thereby facilitating the detection of the capacitor.

Fourth, by providing the upper housing 110b of the component inspection machine with a metal material, the noise in the component inspection machine is prevented from flowing into the product 120 placed on the component inspection machine.

According to the above-described embodiment, it is possible to provide a capacitor detection circuit constructed on the basis of a basic circuit for detecting the presence or absence of a capacitor mounting, a related expression for designing this circuit, a waveform, and the like.

In addition, when a component inspecting apparatus for detecting the actual mounting of the low-capacitance capacitor in the component is manufactured, it is possible to further provide a method for blocking the noise inside and outside the component inspecting device so that the designed capacitor detecting circuit can operate correctly.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims . It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (7)

A square wave is applied to one terminal of a specific capacitor in an antenna peripheral circuit and a voltage between both terminals of a resistor connected between the other terminal of the capacitor and the ground is detected as a voltage at a measuring point, . The method according to claim 1,
Wherein the capacitor is a low capacitance capacitor having a capacitance of 1 kV to 10 kV, and the resistance of the resistor is 1 MΩ or more. The method of claim 2,
Wherein the rising edge and the falling edge of the square wave are set to be close to a right angle. The method according to claim 1,
Further comprising a switch provided between one terminal of the capacitor and the rectangular wave generating unit for generating the rectangular wave, wherein the switch blocks noise from the rectangular wave generating unit in an off state after a predetermined switching operation. A square wave generator for applying a square wave to one terminal of a specific capacitor in an antenna peripheral circuit;
A resistor connected between the other terminal of the capacitor and the ground;
A first amplifier to which a voltage of a measuring point to which the other terminal of the capacitor and the resistor are connected in common is applied to an input terminal;
A first low-pass filter for filtering an output signal of the first amplifier;
A second amplifier for amplifying the output signal of the first low-pass filter;
A first low band pass filter for filtering an output signal of the second amplifier; And
A central processing unit for detecting an output signal of the second low-pass filter;
And a component checker. The method of claim 5,
Further comprising a switch block having a switch provided between one terminal of the capacitor and the rectangular wave generating unit to block noise inside and outside the housing of the component inspecting apparatus on which the rectangular wave generating unit and the power supply unit are mounted,
Wherein the switch is provided with an analog switch or a relay, which injects or momentarily disconnects a signal of a connection cable connected to one terminal of the capacitor. The method of claim 6,
Further comprising a first shielding portion for shielding at least one of the power source device, the rectangular wave generating portion, and the switching power source device for controlling the switch block and supplying power, or when the upper and lower portions of the housing are detachably provided And the upper portion of the housing where the circuit board including the antenna peripheral circuit is placed is provided with a member having a metallic second shielding portion.

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