• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    In the piezoelectric transformer for fluorescent lamps of the present invention, the electrode disposed on the first surface of the piezoelectric block is formed such that the area of the electrode formed in the center region of each side of the first surface of the piezoelectric block is smaller than the area of the electrode formed in the corner region. As a result, the stress applied to the piezoelectric block is minimized to prevent heat from being generated in the piezoelectric block, thereby preventing damage to the piezoelectric block or deterioration of efficiency. The shape of the input electrode can be formed in various shapes such as diamond shape, diamond shape, or rough cross shape.
    公开号:KR20010100598A
    申请号:KR1020000023903
    申请日:2000-05-04
    公开日:2001-11-14
    发明作者:김종선；유충식
    申请人:이형도；삼성전기주식회사；
    IPC主号:
    专利说明:

    Piezoelectric transformer for fluorescent lamps {A PIEZOELECTRIC TRANSFORMER FOR A FLUORESCENT LIGHT}
    [10] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer. In particular, the area of the electrode formed in the center region of the piezoelectric block is smaller than the area of the electrode formed in the corner region to minimize the stress in the center portion of the piezoelectric block, thereby outputting high power, thereby providing a general fluorescent lamp. It relates to a piezoelectric transformer for fluorescent lamps that can be applied.
    [11] Piezoceramic was first developed in the mid 1940s when BaTiO 3 was developed, and Pb (Zr, Ti) O 3 (PZT) was found to have better piezoelectric properties. PZT is a solid solution of PbZr0 3 and PbTiO 3 , which has a perovskite structure and excellent piezoelectric properties. A three-component composite perovskite compound is currently developed to facilitate the change of two-component composition and to further improve piezoelectric properties. It became. Pb (Mg, Nb) O 3 -Pb (Zr, Ti) O 3 , Pb (MG, Ta) O 3 -Pb (Zr, Ti) O 3 , Pb (Mn, Nb) O 3 -Pb (Zr, Ti ) O 3 and the like have been actively studied as a three-component complex perovskite compound. Electrical parts using such piezoelectric materials have been widely used due to the advantages of simplicity of manufacture and improvement of electrical characteristics as well as light weight and shortening.
    [12] An example of applying the piezoelectric material is a band pass filter for amplitude modulation as shown in FIG. 1. In the drawing, Fig. 1 (a) shows a plan view of the bandpass filter and Fig. 1 (b) shows a cross-sectional view along the line A-A. As shown in the figure, the band pass filter has a structure in which electrodes are formed on the upper and lower surfaces of the piezoelectric block 1 formed of a substantially hexahedron. The electrodes formed on the upper surface represent the input electrode 3 and the output electrode 5, respectively, and the electrodes 7 formed on the lower surface represent the common electrode.
    [13] When an AC voltage corresponding to the resonant frequency is applied to the input electrode 3, the applied electrical signal is converted into a strong mechanical vibration near the input side of the piezoelectric block 1, and this mechanical vibration is transmitted to the output to be proportional to the resonant frequency. The voltage is output through the output electrode (5).
    [14] The piezoelectric material has been developed and applied since the late 1910s, and is widely used in high voltage generators, ultrasonic devices, acoustic devices, AM radios, 45.5KHz IF filters, FM radios, 10.7MHZ filters, communication devices, and various sensors. Is being applied. Recently, the application is expanded as a resonator or a filter for a communication device, or used as an inverter of a cold cathode tube for backlighting of liquid crystal displays, and has been developed as a piezoelectric transformer used in a general inverter.
    [15] 2 shows a typical transformer structure in which piezoelectric materials are applied. The transformer shown in the figure is a Rosen type which exhibits thickness vibration and longitudinal vibration, where FIG. 2 (a) shows a perspective view and FIG. 2 (b) shows a sectional view. As shown in the figure, the transformer is polarized in the thickness direction in the region of the input electrodes 3a and 3b formed on the upper and lower portions of the piezoelectric block 1, and in the region of the output electrode 5 formed on the opposite thickness direction thereof. Direction is polarized. When boosting the piezoelectric transformer of the above structure, when an AC voltage corresponding to the resonance frequency is applied to the input electrodes 3a and 3b, the applied electrical signal is converted into strong mechanical vibration in the thickness direction near the input side of the piezoelectric block 1. This mechanical vibration is transmitted to the output side to generate the longitudinal vibration. This longitudinal mechanical vibration is output through the output electrode 5 at a high frequency boosted high voltage of the same frequency as the voltage applied to the input electrode.
    [16] At this time, the high step-up of the output side is maximized when the frequency of the input voltage and the mechanical vibration frequency of the output side are the same, and the step-up ratio of the piezoelectric transformer varies depending on the load impedance, and the step-up ratio is increased when a relatively large load impedance is applied to the output side. It is the maximum. On the other hand, when a low load impedance is applied to the output side, the boost ratio becomes several tens of times or less.
    [17] When a piezoelectric transformer is used for a lamp, such as a cold cathode tube or a fluorescent lamp, the load impedance is different depending on the type of lamp. However, if the piezoelectric transformer is manufactured under optimum conditions, it is possible to maintain a high boost ratio even at a low load impedance. In addition, even after a large load is applied before lighting, a moderate boost ratio is maintained even in a steady state in which low impedance is obtained after lighting, and thus it can be used for a lamp such as a cold cathode tube or a fluorescent lamp.
    [18] In addition, recently, piezoelectric transformers using the contour vibration mode as shown in FIG. 3 have been developed. As shown in the figure, the piezoelectric transformer using the contour vibration mode is similar to the structure of the bandpass filter shown in FIG. 1 and merely has different shapes of electrodes. That is, in the band pass filter shown in FIG. 1, the shape of the input electrode 3 is rectangular, whereas in the transformer, the shape is circular. The output electrode 5 is formed on the upper surface of the piezoelectric block 1 at a predetermined distance from the input electrode 3, and the common electrode 7 is formed on the lower surface of the piezoelectric block 1.
    [19] When a voltage is applied through the input electrode 3, the applied electrical signal is converted into mechanical vibration from the center of the piezoelectric block 1 on which the input electrode 3 is formed by the piezoelectric material to the periphery, and then proportional to the mechanical vibration. The signal is output through the output electrode 5. Such piezoelectric transformers are mainly used as low power transformers, such as for liquid crystal displays of notebook computers.
    [20] However, although various electric devices using piezoelectric transformers are currently produced as described above, high power transformers cannot be manufactured. The piezoelectric transformer (opened in US Pat. No. 6,037,706), which is used for cold cathode tubes or laminated, is not applicable to fluorescent lamps because of its complicated structure and low power. In this case, due to the limitation of the material, a structure in which these piezoelectric agents are laminated is studied. The design of Fluorescent lamp with PFC using a power piezoelectric transformer, Sung Jin Choi, IEEE (1998, 2, 15), P1141 shows that the circular or rectangular electrodes in the contour vibration mode have low power, independent of material problems. This became a problem.
    [21] In addition, a problem occurs due to the structure of the electrode. In the case of a piezoelectric transformer, when a electrical signal is converted into mechanical vibration, a stress of a part of the piezoelectric element is generated to a maximum, and thus a device is damaged or a efficiency is deteriorated. There was.
    [22] The present invention has been made in view of the above, and by minimizing the area of the electrode of the side portion of the piezoelectric block where mechanical vibration is small, it is possible to prevent the piezoelectric block from being broken by minimizing the generation of heat due to stress. It is an object to provide a piezoelectric transformer.
    [23] In order to achieve the above object, the piezoelectric transformer according to the present invention minimizes the heat generated by the stress by reducing the electrode size of the stress generating region on the top of the piezoelectric block. Since stress is mainly generated in the center part of the edge of the piezoelectric block, minimizing the electrode in this area can minimize the stress even when applied to a high-power transformer. To this end, the shape of the electrode may be formed in a diamond shape or approximately cross shape. Moreover, it is not limited to the shape of an electrode, It can also form in various shapes.
    [1] 1 is a view showing the structure of a conventional band pass filter using a piezoelectric material.
    [2] Figure 2 is a view showing the structure of a conventional lozenge piezoelectric transformer using a piezoelectric material.
    [3] Figure 3 is a view showing the structure of a conventional outer vibration mode piezoelectric transformer using a piezoelectric material.
    [4] 4 is a view showing the structure of a piezoelectric transformer for a fluorescent lamp according to an embodiment of the present invention.
    [5] FIG. 5 is a view showing a shape in which mechanical vibration occurs when a voltage is applied to the piezoelectric transformer for fluorescent lamps of the present invention. FIG.
    [6] 6 is a view showing the structure of a piezoelectric transformer for fluorescent lamps according to another embodiment of the present invention.
    [7] -Explanation of symbols for the main parts of the drawings-
    [8] 101,201 piezoelectric block 103,203 input electrode
    [9] 105,205: output electrode 107,207: common electrode
    [24] In general, piezoelectric transformers used for the back light of liquid crystal displays are lozenge-type piezoelectric transformers. These lozenge-type piezoelectric transformers are applied to cold cathode lighting devices, but are adapted to high-voltage and low-current outputs. Was not possible. In ordinary fluorescent lamps, the equivalent impedance of a lamp being lit is several KΩ or less, which is much smaller than the impedance of a cold cathode tube (80 to 100 KΩ).
    [25] The present invention provides a piezoelectric transformer that can be applied to a general fluorescent lamp. In order to form such a piezoelectric transformer, in the present invention, the structure of the electrode is formed differently from the prior art. The reason why the electrode structure is changed as described above is that a maximum stress is generated in a specific region of the piezoelectric body when the electrical signal is converted into mechanical vibration. The present invention provides a piezoelectric transformer capable of outputting a desired voltage and current by changing a region in which stress is generated by converting an electrode structure.
    [26] Hereinafter, the piezoelectric transformer according to the present invention will be described in detail with reference to the accompanying drawings.
    [27] 4 is a diagram illustrating a piezoelectric transformer according to the present invention. FIG. 4 (a) shows a plan view of the piezoelectric transformer and FIG. 4 (b) shows a sectional view. As shown in the figure, the piezoelectric transformer of the present invention includes a piezoelectric block 101 formed in a substantially hexahedral shape, an input electrode 103 and an output electrode 105 formed on an upper surface of the piezoelectric block 101, and the piezoelectric body. The common electrode 107 is formed on the bottom surface of the block 101.
    [28] The input electrode 103 has a substantially rhombus shape or diamond shape, and the input electrode 103 and the output electrode 105 are separated by a set distance. The common electrode 107 is integrally formed with at least a portion of the lower surface of the piezoelectric block 101 without being separated.
    [29] In the piezoelectric transformer of the above structure, when an electrical signal is input through the input electrode 103 and the common electrode 107, the electrical signal is converted into mechanical vibration in the piezoelectric block 101 and then the output. A signal proportional to mechanical vibration is output through the electrode 105.
    [30] As indicated by the dashed-dotted line of FIG. 5, the vibration of the piezoelectric block 101 due to the application of voltage is the largest at the corner portion of the piezoelectric block 101 and the smallest at the center region of the side. Arrows in the corners in the drawing indicate the degree of vibration of the piezoelectric block 101. The degree of vibration may of course vary depending on the material of the piezoelectric material or the magnitude of the applied voltage.
    [31] As described above, since the mechanical vibration is the greatest in the corner portion of the piezoelectric block 101 and the vibration in the center region of the side (P point in the figure) is the smallest, the piezoelectric block 101 is operated when the piezoelectric transformer is applied by applying voltage. The maximum stress acts on the center of the c) and becomes the next higher stress point in the center region of the side of the piezoelectric block 101. The generation of such a stress eventually causes heat to be generated in the center region of the side, which has a serious effect on the piezoelectric block 101.
    [32] In general, when an electrical signal is input and converted into mechanical vibration by application of a voltage, the vibration mainly occurs strongly at the input electrode and the output electrode. Therefore, when the size of the electrode of the central region P of the large stress side is reduced, the degree of vibration is small, so that the stress is small, and as a result, the generation of heat can be reduced.
    [33] In the present invention, for this purpose, as shown in the figure, the shape of the input electrode 103 is formed in a diamond shape. Therefore, a region where no electrode is formed between the input electrode 103 and the output electrode 105 approaches the center region P of the side of the hexahedral piezoelectric block 101, so that the size of the electrode in the region P is increased. Will decrease.
    [34] In the case where the input electrode 103 is formed in the diamond shape as described above, since the electromechanical coupling coefficient Kp in the radial direction is larger than the coupling coefficient K31 in the longitudinal direction, the energy conversion efficiency is not only improved, but also the electrostatic on the output side. Increased capacity acts to reduce the impedance at the output side. Therefore, the output power to the output side can be increased. In addition, when the input electrode 103 is formed in a diamond shape, the boost ratio is relatively reduced, which is useful for lighting a fluorescent lamp having a low impedance at the time of lighting.
    [35] As described above, the shape of the input electrode 103 of the piezoelectric transformer of the present invention need not be limited to diamond. In other words, in the present invention, the smaller the size of the electrode in the side center region P of the piezoelectric block 101, the smaller the stress becomes, regardless of the shape of the electrode.
    [36] As shown in FIG. 4B, the common electrode 107 is formed in a pattern on at least a portion of the lower surface of the piezoelectric block 101 so that an external circuit of the input electrode 103 and the output electrode 105 (not shown) is shown. And noise may be input from an external circuit through the common electrode 107. In order to solve this problem, as shown in FIG. 6A, the common electrode 207 formed under the piezoelectric block 201 may be isolated. By isolation of the common electrode 207, noise can be prevented from being input from an external circuit. The common electrode 207 illustrated in FIG. 6A has a shape different from that of the input electrode 203 and the output electrode 205 formed on the upper surface of the piezoelectric block 201, but is illustrated in FIG. 6B. As described above, the input electrode 203 and the output electrode 205 may be formed in the same shape and size, that is, symmetrical to each other.
    [37] As described above, in the piezoelectric transformer according to the present invention, the area of the electrode formed in the center region of each side of the piezoelectric block is formed smaller than the area of the electrode formed in the corner region. Therefore, the shape of the electrode does not need to be specified, and the electrode area of the center area may be smaller than the electrode area of the edge area as described above. To this end, the shape of the input electrode can be formed into various shapes such as diamond, rhombus or cross.
    [38] As described above, the piezoelectric block according to the present invention reduces the size of the electrode at the point where stress occurs to the maximum and minimizes the stress, so that the piezoelectric block is damaged or the efficiency of the piezoelectric block is generated even when it is adapted to a high voltage piezoelectric transformer. The degradation can be prevented.
    权利要求:
    Claims (8)
    [1" claim-type="Currently amended] A piezoelectric block made of a piezoelectric material to convert electrical signals into mechanical vibrations;
    An input electrode formed in the center region of the first surface of the piezoelectric block to receive an electrical signal;
    An output electrode formed in a peripheral area of the first surface of the piezoelectric block at a predetermined interval from the input electrode and outputting an electrical signal after converting the signal converted into mechanical vibration by the piezoelectric body; And
    A common electrode formed on the second surface of the piezoelectric block;
    The input electrode and the output electrode is a piezoelectric transformer, characterized in that formed in a shape that the area of the electrode formed in the center region of the side of the first surface of the piezoelectric block is minimized.
    [2" claim-type="Currently amended] The piezoelectric transformer according to claim 1, wherein the input electrode has a diamond shape.
    [3" claim-type="Currently amended] The piezoelectric transformer of claim 1, wherein the common electrode is integrally formed on at least a portion of the second surface of the piezoelectric block.
    [4" claim-type="Currently amended] The piezoelectric transformer of claim 1, wherein the common electrode is formed of a plurality of isolations on the second surface of the piezoelectric block to prevent noise from being input from the outside.
    [5" claim-type="Currently amended] The piezoelectric transformer of claim 4, wherein the common electrode is substantially opposite to an input electrode and an output electrode formed on the first surface of the piezoelectric block.
    [6" claim-type="Currently amended] The piezoelectric transformer according to claim 1, wherein the input electrode is formed in a diamond shape so that the area of the output electrode in the center region of the first surface of the piezoelectric block is smaller than the area of the output electrode in the corner region.
    [7" claim-type="Currently amended] The piezoelectric transformer according to claim 1, wherein the input electrode has a substantially cross shape.
    [8" claim-type="Currently amended] A piezoelectric block made of a piezoelectric material to convert electrical signals into mechanical vibrations;
    An input electrode formed closer to the center region of each side of the piezoelectric block than the edge of the first surface to receive an electrical signal;
    It is arranged in the peripheral area of the first surface of the piezoelectric block at a predetermined interval from the input electrode so that the area formed in the center area of each side of the piezoelectric block is formed smaller than the area formed in the corner area and converted into mechanical vibration by the piezoelectric body. An output electrode converting the output signal back into an electrical signal and outputting the converted signal; And
    A piezoelectric transformer comprising a common electrode formed on the second surface of the piezoelectric block.
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2000-05-04|Application filed by 이형도, 삼성전기주식회사
    2000-05-04|Priority to KR1020000023903A
    2000-05-04|Priority claimed from KR1020000023903A
    2001-11-14|Publication of KR20010100598A
    2002-08-17|Application granted
    2002-08-17|Publication of KR100349126B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR1020000023903A|KR100349126B1|2000-05-04|A piezoelectric transformer for a fluorescent lamp|
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