阅读说明：本技术 一种驱动电路及电池监测开关的高压多路复用器 (High-voltage multiplexer of driving circuit and battery monitoring switch ) 是由 朱光前 张启东 李二鹏 杨银堂 于 2021-07-16 设计创作，主要内容包括：本发明提供一种应用于高压多路复用器的驱动电路,所述驱动电路用于控制高压多路复用器中开关模块的导通状态；所述驱动电路包括：下拉电流生成模块、输出驱动生成模块和输出反馈模块；下拉电流生成模块：将偏置电压信号转化为下拉电流；输出驱动生成模块：产生输出驱动信号,用于驱动控制高压多路复用器的开关模块的导通状态；输出反馈模块：对高压多路复用器开关模块的输出信号进行反馈,进而在输出驱动生成模块产生输出驱动信号。本发明具有以下优点：本发明的驱动电路结构简单、可靠性高；而且可以在电池监测开关的高压多路复用器中进行复用,能够保证电压传输模块严格关闭,同时别的开关不会误开启,其他严格关闭的通道并不影响正常通道的开启。(The invention provides a driving circuit applied to a high-voltage multiplexer, which is used for controlling the conducting state of a switch module in the high-voltage multiplexer; the drive circuit includes: the device comprises a pull-down current generation module, an output drive generation module and an output feedback module; a pull-down current generation module: converting the bias voltage signal into a pull-down current; an output drive generation module: generating an output driving signal for driving and controlling the conducting state of a switch module of the high-voltage multiplexer; an output feedback module: and feeding back the output signal of the high-voltage multiplexer switch module, and generating an output driving signal at an output driving generation module. The invention has the following advantages: the driving circuit of the invention has simple structure and high reliability; and can multiplex in the high-voltage multiplexer of battery monitoring switch, can guarantee that voltage transmission module closes strictly, other switches can not open by mistake simultaneously, and the opening of normal passageway is not influenced to other passageways that close strictly.)

1. A kind of drive circuit used in high-voltage multiplexer is characterized in that:

the drive circuit is used for controlling the conducting state of the switch module in the high-voltage multiplexer; the drive circuit includes: the device comprises a pull-down current generation module, an output drive generation module and an output feedback module;

a pull-down current generation module: providing a pull-down current for the output drive generation module;

an output drive generation module: generating an output driving signal for driving and controlling the conducting state of a switch module of the high-voltage multiplexer;

an output feedback module: and feeding back the output signal of the high-voltage multiplexer switch module, and generating an output driving signal at an output driving generation module.

2. The driving circuit applied to a high-voltage multiplexer according to claim 1, wherein:

the pull-down current generation module converts an externally input bias voltage signal into a pull-down current through an amplifier.

3. The driving circuit applied to the high-voltage multiplexer as recited in claim 2, wherein:

the amplifier is a common source amplifier.

4. A driver circuit for a high voltage multiplexer as claimed in claim 3, wherein:

the amplifier is a common source amplifier and comprises an NMOS (N-channel metal oxide semiconductor) transistor MN8 and a resistor R3;

the gate of the MN3 is connected with a bias voltage signal, the source of the MN3 is grounded, and the drain of the MN3 is connected with one end of the resistor R3;

the other end of the resistor R3 is connected with the output drive generation module to provide a pull-down current I3 for the output drive generation module.

5. The driving circuit applied to a high-voltage multiplexer according to claim 1, wherein:

the output drive generation module is a current mirror with a cascode structure;

the input of the output drive generation module is connected with the other end of the resistor R3 in the pull-down current generation module;

the output of the output drive generation module is an output drive signal.

6. The driving circuit applied to the high-voltage multiplexer according to claim 5, wherein:

the current mirror of the cascode structure comprises PMOS tubes MP8, MP9, MP4 and MP 5;

the gates of the PMOS tubes MP8, MP9, MP4 and MP5 and the drain of the MP5 are connected with the other end of the resistor R3;

the sources of the MP8 and the MP9 are connected with a power supply voltage;

the drain electrode of the MP8 is connected with the source electrode of the MP 4;

the drain electrode of the MP9 is connected with the source electrode of the MP 5;

the drain of the MP4 is connected to the output drive signal.

7. The driving circuit applied to the high-voltage multiplexer as recited in claim 6, wherein:

the PMOS tubes MP4 and MP5 are double-diffusion PMOS tubes.

8. The driving circuit applied to a high-voltage multiplexer according to claim 1, wherein:

the output feedback module comprises a PMOS (P-channel metal oxide semiconductor) tube MP3 and a resistor R2;

the gate of the PMOS transistor MP3 is connected to the output signal, the source is connected to the output driving signal, and the drain is connected to the ground through the resistor R2.

9. A high voltage multiplexer for a battery monitoring switch, comprising a driver circuit according to any one of claims 1 to 8, wherein:

the high-voltage multiplexer of the battery monitoring switch further comprises a bias module and a switch module;

a biasing module: providing bias voltage and bias current for the switch module and the driving circuit;

a switch module: and the input voltage signals of the multiple batteries are collected through the control of the driving circuit.

10. The high voltage multiplexer for a battery monitoring switch of claim 9, wherein:

the bias module comprises a pull-up current generation module and a bias voltage generation module; the bias voltage generation module: converting the input bias current into a bias voltage signal and providing a working current I4 for the pull-up current generation module;

the pull-up current generation module: and providing bias current for the switch module, and converting the working current I4 into a pull-up current signal through a current mirror structure.

Technical Field

The invention relates to the technical field of electronics, in particular to a high-voltage multiplexer of a driving circuit and a battery monitoring switch.

Background

A Battery Monitoring and management Integrated Circuit (BMIC) usually needs to collect and detect voltages of multiple batteries, and stacking of multiple batteries inevitably introduces a high-voltage signal, which easily affects the collection and detection accuracy of the BMIC on the multiple batteries. If the battery voltage is collected separately for each channel in the chip, a plurality of ADC modules are introduced into the circuit, which greatly increases the circuit area and power consumption. Usually, only one battery unit is sampled in the same conversion period, so that the measurement of multiple channels can be realized by only 1 ADC by selecting the battery unit by using the multiplexer structure, which greatly reduces the circuit area and saves the power consumption. As shown in the functional block diagram of the structure of the integrated circuit chip for battery monitoring and management in fig. 1, the high voltage multiplexer module is mainly used to select the channel.

The prior art has the following defects: in the high-voltage multiplexer module, in order to meet the requirement of multi-channel acquisition, a sampling switch circuit needs to be designed for each channel. Generally, the acquisition front-end circuit is matched with one driving circuit for one group of switches, which requires designing a plurality of driving circuits for a plurality of groups of switches. The multiple driving circuits not only increase the power consumption and area of the circuit, but also reduce the reliability of the chip.

Disclosure of Invention

In order to solve the problems:

according to a first aspect of the present invention, the present invention provides a driving circuit applied to a high voltage multiplexer, the driving circuit is used for controlling the conducting state of a switch module in the high voltage multiplexer; the drive circuit includes: the device comprises a pull-down current generation module, an output drive generation module and an output feedback module;

a pull-down current generation module: converting the bias voltage signal into a pull-down current; providing a pull-down current for the output drive generation module, wherein the pull-down current is a bias current of the drive generation module;

an output drive generation module: generating an output driving signal for driving and controlling the conducting state of a switch module of the high-voltage multiplexer;

an output feedback module: and feeding back the output signal of the high-voltage multiplexer switch module, and generating an output driving signal at an output driving generation module.

Preferably, the pull-down current generation module converts an externally input bias voltage signal into a pull-down current through an amplifier.

Further preferably, the amplifier is a common source amplifier.

Still further preferably, the common source amplifier comprises an NMOS transistor MN8 and a resistor R3;

the gate of the MN3 is connected with a bias voltage signal, the source of the MN3 is grounded, and the drain of the MN3 is connected with one end of the resistor R3;

the other end of the resistor R3 is connected with the output drive generation module to provide a pull-down current I3 for the output drive generation module.

Preferably, the output driving generation module is a current mirror with a cascode structure;

the input of the output drive generation module is connected with the other end of the resistor R3 in the pull-down current generation module;

the output of the output drive generation module is an output drive signal.

Further preferably, the current mirror of the cascode structure includes PMOS transistors MP8, MP9, MP4 and MP 5;

the gates of the PMOS tubes MP8, MP9, MP4 and MP5 and the drain of the MP5 are connected with the other end of the resistor R3;

the sources of the MP8 and the MP9 are connected with a power supply voltage;

the drain electrode of the MP8 is connected with the source electrode of the MP 4;

the drain electrode of the MP9 is connected with the source electrode of the MP 5;

the drain of the MP4 is connected to the output drive signal.

Further preferably, the PMOS transistors MP4 and MP5 are double diffused PMOS transistors.

Preferably, the output feedback module comprises a PMOS transistor MP3 and a resistor R2;

the gate of the PMOS transistor MP3 is connected to the output signal, the source is connected to the output driving signal, and the drain is connected to the ground through the resistor R2.

The specific technical solution of the invention is as follows:

according to a second aspect of the present invention, the present invention provides a high voltage multiplexer of a battery monitoring switch, wherein the driving circuit further includes a bias module and a switch module;

a biasing module: providing bias voltage or bias current for the switch module and the driving circuit;

a switch module: and the input voltage signals of the multiple batteries are collected through the control of the driving circuit.

Preferably, the bias module comprises a pull-up current generation module and a bias voltage generation module;

the bias voltage generation module: converting the input bias current into a bias voltage signal and providing a working current I4 for the pull-up current generation module;

the pull-up current generation module: the working current I4 is converted into a pull-up current signal I5 through a current mirror structure, and the pull-up current signal I5 serves as a bias current of the driving circuit.

Further preferably, the current mirror structure is a cascode current mirror;

still further preferably, the cascode-structured current mirror; comprises PMOS tubes MP10, MP11, MP6 and MP 7;

the gates of the PMOS tubes MP10, MP11, MP6 and MP7 are connected with the drain of the MP7 and the working current signal I4 of the bias voltage generation module;

the sources of the MP10 and the MP11 are connected with a power supply voltage;

the drain electrode of the MP10 is connected with the source electrode of the MP 6;

the drain electrode of the MP11 is connected with the source electrode of the MP 7;

the drain of the MP6 is connected to the pull-up current signal.

Still further preferably, the PMOS transistors MP6 and MP7 are double diffused PMOS transistors.

Preferably, the bias voltage generating module comprises NMOS transistors MN1, MN2, and MN 3;

the sources of the NMOS transistors MN1 and MN2 are grounded;

the gates of the NMOS transistors MN1, MN2 and MN3 are connected with an input bias current signal and a bias voltage signal;

the drain electrode of the NMOS transistor MN2 is connected with the source electrode of the MN 3;

the drain of the NMOS transistor MN3 outputs a working current signal I4.

Further preferably, the NMOS transistor MN3 is a double-diffused NMOS transistor.

Preferably, the switch module comprises a voltage transmission module, a pull-down control module, and zener diodes D1 and D2;

a voltage transmission module: the input voltage signals of the high-voltage multi-path batteries are collected under the control of the pull-down control module and the driving circuit;

a pull-down control module: controlling the conduction state of the voltage transmission module through different states of the control signal and the driving circuit;

the positive end of the voltage stabilizing diode D1 is connected with the pull-up current signal, and the reverse end of the voltage stabilizing diode D1 is connected with the output driving signal;

the positive end of the voltage stabilizing diode D2 is connected with the output signal; the inverting terminal is connected to the output drive signal and D2.

Further preferably, the voltage transmission module comprises a resistor R1, a double-diffused PMOS transistor MP1 and MP 2;

one end of the resistor R1 and the source electrode of the MP1 are connected with the collected voltage signal VIN of the high-voltage multi-path battery;

the other end of the resistor R1 and the gate of the MP1 are connected with a first current signal I1;

the drain electrode of the MP1 is connected with the drain electrode of the MP 2;

the source of the MP2 is connected with the output signal;

the gate of the MP2 is connected to the pull-up current signal and a second current signal I2.

Still further preferably, the pull-down control module comprises NMOS transistors MN4, MN5, MN6 and MN 7;

the sources of the MN4 and the MN5 are grounded, and the gates of the MN4 and the MN5 are connected with the bias voltage signal;

the drains of the MN4 and the MN5 are respectively connected with the sources of the MN6 and the MN 7;

the gates of the MN6 and the MN7 are connected with control signals;

the drain of the MN6 is connected with the pull-up current signal and a second current signal I2;

preferably, the switching circuits are connected in parallel by at least 2.

The invention has the following advantages: the driving circuit of the invention has simple structure and high reliability; and can multiplex in the high-voltage multiplexer of battery monitoring switch, can guarantee that voltage transmission module closes strictly, other switches can not open by mistake simultaneously, and the opening of normal passageway is not influenced to other passageways that close strictly.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a functional block diagram of an integrated circuit chip architecture for battery monitoring and management;

FIG. 2 is a functional block diagram of the high voltage multiplexer of the present invention;

FIG. 3 is a functional block diagram of a driver module of the present invention;

FIG. 4 is a functional block diagram of the biasing module of the present invention;

FIG. 5 is a functional block diagram of a switch module of the present invention;

FIG. 6 is a circuit schematic of the drive module of the present invention;

FIG. 7 is a circuit schematic of the bias module of the present invention;

FIG. 8 is a circuit schematic of the switch module of the present invention;

FIG. 9 is a circuit schematic of the high voltage multiplexer of the battery monitor switch of the present invention;

fig. 10 is a schematic diagram of the application of the high voltage multiplexer of the battery monitor switch of the present invention.

Detailed Description

The present invention will be described more fully with reference to the following embodiments and accompanying drawings.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The driving circuit and the high-voltage multi-path battery monitoring switch provided by the invention are explained in detail by several specific embodiments.

As shown in fig. 2, the functional block diagram of the high voltage multiplexer of the present invention includes a driving module 11, a bias module 12 and a switch module 13;

the driving module 11 is used for controlling the conducting state of the switch module in the high-voltage multiplexer;

the bias module 12: providing bias voltage or bias current for the switch module and the driving circuit;

the switch module 13: and the input voltage signals of the multiple batteries are collected through the control of the driving circuit. When the switch module 13 is in the on state, the voltages of the multiple battery packs connected to the switch module 13 are collected through the switch module 13, that is, the voltages of the multiple battery packs are input to a post-processing circuit (not shown) through the switch module 13.

The following description is provided for each module:

FIG. 3 is a functional block diagram of the driver module of the present invention; the driving module 11 (also called as a driving circuit) is used for controlling the conducting state of the switch module in the high-voltage multiplexer; the method comprises the following steps: a pull-down current generation module 113, an output drive generation module 111 and an output feedback module 112;

the pull-down current generation module 113: converting the bias voltage signal into a pull-down current;

the output drive generation module 111: generating an output driving signal for driving and controlling the conducting state of a switch module of the high-voltage multiplexer;

the output feedback module 112: and feeding back the output signal of the high-voltage multiplexer switch module, and generating an output driving signal at an output driving generation module.

FIG. 4 is a functional block diagram of the biasing module of the present invention; the bias module 12 includes a pull-up current generation module 121 and a bias voltage generation module 122;

the bias voltage generation module 122: converting the input bias current into a bias voltage signal and providing a working current I4 for the pull-up current generation module;

pull-up current generation module 121: the working current I4 is converted into a pull-up current signal I5 through a current mirror structure.

FIG. 5 is a functional block diagram of the switch module of the present invention; the switch module 13 includes a voltage transmission module 131, a pull-down control module 132, zener diodes D1 and D2;

voltage transmission module 131: the input voltage signal of the high-voltage multi-path battery is collected through the control of the pull-down control module 132 and the driving circuit 11;

the pull-down control module 132: controlling the conducting state of the voltage transmission module through different states of the control signal and the driving circuit 11;

the positive end of the voltage stabilizing diode D1 is connected with the pull-up current signal, and the reverse end of the voltage stabilizing diode D1 is connected with the output driving signal;

the positive end of the voltage stabilizing diode D2 is connected with the output signal; the inverting terminal is connected to the output drive signal and D2.

The specific structure of each module is described in detail below:

FIG. 6 is a schematic circuit diagram of the driver module of the present invention; the pull-down current generation module 113 amplifier converts an externally input bias voltage signal into a pull-down current. The amplifier is a common source amplifier. Of course, if the amplifier is a bipolar process, the amplifier may also be a cascode triode structure amplifier. The amplifier is a common source amplifier and comprises an NMOS transistor MN8 and a resistor R3; the gate of MN3 is connected with bias voltage signal, the source of MN3 is grounded, and the drain of MN3 is connected with one end of the resistor R3; the other end of the resistor R3 is connected to the output driving generation module to provide a pull-down current I3 for the output driving generation module 111.

The output driving generation module 111 is a current mirror with a cascode structure; the input of the output drive generation module 111 is connected to the other end of the resistor R3 in the pull-down current generation module 113; the output of the output drive generation module 111 is an output drive signal. The current mirror of the cascode structure of the output drive generation module 111 includes PMOS transistors MP8, MP9, MP4, and MP 5; the gates of PMOS tubes MP8, MP9, MP4 and MP5 and the drain of MP5 are connected with the other end of the resistor R3; the sources of the MP8 and the MP9 are connected with the power supply voltage; the drain of the MP8 is connected with the source of the MP 4; the drain of the MP9 is connected with the source of the MP 5; the drain of MP4 is connected to the output drive signal. Particular PMOS transistors MP4 and MP5 may be double diffused PMOS transistors (shown schematically as DMP4 and DMP 5).

The output feedback module 112 comprises a PMOS transistor MP3 and a resistor R2; the gate of the PMOS transistor MP3 is connected to the output signal, the source is connected to the output driving signal, and the drain is connected to the ground through the resistor R2. A particular PMOS transistor MP3 may be a double diffused PMOS transistor (shown schematically as DMP 3).

The advantage of using double diffused PMOS transistors here is that they can withstand higher voltages to meet the use of the large voltage if the number of cells in series is large. The double diffused MOS transistors mentioned in the context of the present invention are all intended to be able to satisfy the use of higher voltages.

FIG. 7 is a circuit schematic of the bias module of the present invention; the bias module 12 comprises a pull-up current generation module 121 and a bias voltage generation module 122; the pull-up current generation module 121 converts the operating current I4 into a pull-up current signal I5 through a current mirror structure. The current mirror structure is a current mirror of a cascode structure; a current mirror of cascode configuration; comprises PMOS tubes MP10, MP11, MP6 and MP 7; the gates of the PMOS tubes MP10, MP11, MP6 and MP7 are connected with the drain of the MP7 and the working current signal I4 of the bias voltage generation module; the sources of the MP10 and the MP11 are connected with the power supply voltage; the drain of the MP10 is connected with the source of the MP 6; the drain of the MP11 is connected with the source of the MP 7; the drain of MP6 is connected to the pull-up current signal. The PMOS tubes MP6 and MP7 are double-diffused PMOS tubes.

The bias voltage generating module 122 comprises NMOS transistors MN1, MN2, and MN 3; the sources of the NMOS transistors MN1 and MN2 are grounded; the gates of the NMOS tubes MN1, MN2 and MN3 are connected with an input bias current signal and a bias voltage signal; the drain electrode of the NMOS tube MN2 is connected with the source electrode of the MN 3; the drain of the NMOS transistor MN3 outputs the operating current signal I4. The NMOS transistor MN3 is a double diffused NMOS transistor (illustrated schematically as DMN 3).

As shown in the schematic circuit diagram of the switch module of fig. 8, the voltage transmission module 131 includes a resistor R1, a double diffused PMOS transistor MP1 and MP 2; one end of the resistor R1 and the source electrode of the MP1 are connected with the collected voltage signal VIN of the high-voltage multi-path battery; the other end of the resistor R1 and the gate of the MP1 are connected with a first current signal I1; the drain of the MP1 is connected with the drain of the MP 2; the source of the MP2 is connected with the output signal; the gate of the MP2 is connected to the pull-up current signal and the second current signal I2.

The pull-down control module 132 comprises NMOS transistors MN4, MN5, MN6 and MN 7; the sources of MN4 and MN5 are grounded, and the gates are connected with the bias voltage signal; the drains of MN4 and MN5 are connected with the sources of MN6 and MN7 respectively; the gates of MN6 and MN7 are connected with control signals; the drain of the MN6 is connected with the pull-up current signal and a second current signal I2; the NMOS transistors MN6 and MN7 may be double diffused NMOS transistors (illustrated as DMN6 and DMN 7).

As a preferred embodiment, fig. 9 shows a schematic circuit diagram of the high voltage multiplexer of the battery monitor switch of the present invention; the driving module 11, the bias module 12 and the switch module 13 of the high voltage multiplexer are connected. It should be noted here that a plurality of switch modules 13 may be connected in parallel, so that the present invention can be applied to a case where a plurality of batteries are connected in series.

The operation of the switch of fig. 9 will be briefly described.

When the control signal is at a low level, the voltage transmission module is closed. The DMN7 and DMN6 tubes are not conducted, no voltage drop exists at two ends of R1, the DMP1 tube is not conducted, the grid voltage of the DMP2 tube is influenced by a pull-up current signal I5 and is pulled to a high level (power supply voltage), and at the moment, the VSG of the switch tube DMP2 is switched on_DMP2＝V_outa-V_PPBelow 0, DMP2 will not turn on. The channel is strictly (voltage transfer module) closed. This ensures that selection of a switch does not result in false activation of another switch.

When the control signal is at a high level, the voltage transmission module is started. The DMN7 and DMN6 tubes are conducted, and the voltage drop generated at the two ends of R1 is used for providing stable grid-source voltage for the DMP1 tube to enable the DMN 1 tube to be started. When the voltage drop VSG is generated across R1_DMP1＝I_b1·R₁So that the DMP1 tube is conducted; the DMP2 transistor gate voltage is pulled to a low level, VSG_DMP2＝V_D1-V_D2The difference between the regulated values of the voltage regulator tubes D1 and D2 turns on the DMP2 tube, and finally makes the voltage of the output signal of the switch group ≈ VIN (i.e., the output voltage of the voltage transmission module is equal to the input voltage). Due to the multiplexing of the driver module 11, other strictly closed channels do not affect the opening of the channel.

As shown in fig. 10, an application diagram of the high voltage multiplexer of the battery monitoring switch of the present invention is that a plurality of batteries (illustrated as n in the figure) are connected in series on the left, one end of a plurality of switch modules 13 (illustrated as n +1 in the figure) is respectively connected to one end of a battery pack connected in series, the other ends of the plurality of switch modules 13 are commonly connected to a driving circuit (driving module 11), the plurality of switch modules 13 are respectively controlled by a control signal and are commonly driven by the driving circuit (driving module 11); in this way, the plurality of switch modules 13 can be respectively conducted for collecting the serial voltages of different ports of the battery pack. The collected voltage can be processed by a subsequent circuit through an analog-to-digital converter. The illustration does not imply a biasing module.

Compared with the prior art, the driving circuit has the advantages of simple structure and high reliability; and can multiplex in the high-voltage multiplexer of battery monitoring switch, can guarantee that voltage transmission module closes strictly, other switches can not open by mistake simultaneously, and the opening of normal passageway is not influenced to other passageways that close strictly.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.