JP2005317553A - Discharge tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently actuate a discharge tube such as a cold cathode fluorescence tube. <P>SOLUTION: The discharge tube is provided with a negative electrode and a positive electrode installed facing each other, a voltage transformer varying the voltage supplied to the positive electrode or the negative electrode and a retaining means to retain the voltage transformer inside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discharge tube, and is particularly suitable when applied to a cold cathode fluorescent tube.

  In recent years, portable information terminal devices such as notebook personal computers and palmtop personal computers have become widespread, and liquid crystal display devices are included in the display units of these portable information terminal devices from the viewpoints of miniaturization, weight reduction, and low power consumption. It was mainly used. A cold cathode tube is frequently used as a light source of a backlight of the liquid crystal display device, and an AC high voltage is required to light the cold cathode tube. For this reason, an AC high voltage is generated by using an AC inverter transformer of an electromagnetic conversion system, and a cold cathode tube is lit.

  FIG. 22 is a diagram showing a conventional cold cathode tube driving method.

  In FIG. 22, a DC voltage of about 10 to 15 V is supplied from the DC power supply 271 to the inverter circuit 272. The inverter circuit 272 converts the DC voltage supplied from the DC power supply 271 into an AC high voltage of about 1200 V / 50 KHz and supplies it to the cold cathode tube 273. When the AC high voltage is supplied from the inverter circuit 272 to the cold cathode tube 273, the cold cathode tube 273 is discharged and lit.

  However, in the conventional cold-cathode tube driving method, it is necessary to perform high-voltage wiring from the inverter circuit 272 to the cold-cathode tube 273, and the power supplied from the inverter circuit 272 passes through the electrostatic stray capacitance associated with the high-voltage wiring. There was a problem of leakage. For this reason, there is a problem that the power consumption when driving the cold cathode tube increases, and when the cold cathode tube is used for the backlight of the portable information terminal device, the battery life of the portable information terminal device is shortened. It was.

  Accordingly, an object of the present invention is to enable the discharge tube to operate efficiently.

  In order to solve the above-described problems, according to the present invention, the discharge tube is discharged by boosting the voltage input to the discharge tube inside the discharge tube.

  As a result, it is possible to discharge the discharge tube simply by inputting a low voltage to the discharge tube. Therefore, when a voltage is input to the discharge tube, power leaks to the outside due to the floating capacitance of the wiring. This can be reduced, and the discharge tube can be operated efficiently.

  Further, according to one aspect of the present invention, the driving means for driving the boosting means is provided inside the discharge tube.

  This makes it possible to discharge the discharge tube simply by inputting a DC low voltage to the discharge tube, and to further reduce the leakage of electric power to the outside when the voltage is input to the discharge tube. Therefore, the discharge tube can be operated more efficiently.

  According to another aspect of the present invention, the discharge tube is a cold cathode tube.

  As a result, the discharge tube can be reduced in size and weight, and can be operated with low power consumption.

  Moreover, according to one aspect of the present invention, the boosting means is a piezoelectric transformer.

  This makes it possible to easily obtain a high step-up ratio, and even when the boosting means is provided inside the discharge tube, it is possible to easily reduce the size and weight of the discharge tube, Can be prevented from increasing.

  Further, according to one aspect of the present invention, a cathode and an anode provided opposite to each other, a piezoelectric transformer that boosts a voltage supplied to the cathode or the cathode, and the cathode, the anode, and the piezoelectric transformer together with a discharge gas. Sealing means for sealing.

  This makes it possible to easily obtain an AC high voltage inside the discharge tube simply by inputting an AC low voltage to the discharge tube, so that power leaks to the outside when the voltage is input to the discharge tube. This can reduce the power consumption of the discharge tube.

  Further, according to one aspect of the present invention, the piezoelectric transformer is held at the node of vibration.

  As a result, the piezoelectric transformer can be held inside the discharge tube without lowering the output voltage of the piezoelectric transformer, and boosting inside the discharge tube can be performed efficiently.

  Further, according to one aspect of the present invention, a driving circuit for driving the piezoelectric transformer is enclosed in the discharge tube.

  As a result, it becomes possible to convert a DC voltage into an AC voltage inside the discharge tube, and an AC high voltage can be easily obtained inside the discharge tube, and only a DC voltage is input to the discharge tube. Therefore, it is possible to discharge the discharge tube, so that it is possible to further reduce the leakage of power when inputting voltage to the discharge tube, and to further reduce the power consumption of the discharge tube. Is possible.

  Further, according to one aspect of the present invention, the pattern of the drive circuit is formed on the piezoelectric transformer.

  Thus, even when the drive circuit is provided in the discharge tube, it is possible to prevent the size of the discharge tube from increasing, and the discharge tube can be reduced in size, weight, and efficiency.

  According to one aspect of the present invention, the drive circuit includes an oscillation circuit and a feedback circuit that feeds back the output of the piezoelectric transformer to the oscillation circuit.

  This makes it possible to change the driving conditions of the piezoelectric transformer based on the actual driving characteristics of the piezoelectric transformer, and to prevent the step-up ratio of the piezoelectric transformer from being lowered due to fluctuations in the operating state of the piezoelectric transformer. Is possible.

  In addition, according to one aspect of the present invention, the oscillation frequency of the oscillation circuit is changed in accordance with a change in the resonance frequency of the piezoelectric transformer.

  As a result, even when the resonance characteristics of the piezoelectric transformer change due to fluctuations in the drive signal level, temperature, load, etc., the piezoelectric transformer can be driven at an optimal frequency, and the piezoelectric transformer can be operated efficiently. It becomes possible.

  Further, according to one aspect of the present invention, the piezoelectric substrate having the first region polarized in the thickness direction and the second region polarized in the length direction, and the upper and lower surfaces of the first region are provided. The secondary electrode is provided on the end face of the second region, and the secondary electrode serves as the cathode or anode of the discharge tube.

  As a result, when the piezoelectric transformer is held inside the discharge tube, it is possible to omit at least one of the cathode and the anode of the discharge tube, thereby reducing the power consumption of the discharge tube and reducing the size and weight. It becomes possible.

  Further, according to one aspect of the present invention, the secondary electrode is sealed inside the discharge tube, and the primary electrode is provided outside the discharge tube.

  As a result, the discharge tube can be reduced in size, and the drive circuit is provided outside the discharge tube even when the drive circuit for driving the piezoelectric transformer is provided on the piezoelectric substrate and the wiring length is shortened. It becomes possible to eliminate the influence of the discharge of the discharge tube on the drive circuit.

  Further, according to one aspect of the present invention, the length of the piezoelectric substrate is made substantially equal to the length of the discharge tube.

  As a result, the high-voltage wiring can be shortened, so that leakage of power to the outside due to the floating capacitance of the wiring can be reduced, and the discharge tube can be operated efficiently. .

  Further, according to one aspect of the present invention, a piezoelectric transformer is provided for each of the anode and the cathode of the discharge tube, and the alternating current voltage in which the phases of the anode and cathode piezoelectric transformers are opposite to each other. I try to drive it.

  As a result, the potential difference between the anode and the cathode of the discharge tube can be increased, and the discharge tube can be discharged more efficiently.

  Further, according to one aspect of the present invention, a piezoelectric transformer having a length substantially equal to the length of the discharge tube is used for an inverter that drives the discharge tube.

  This makes it possible to shorten the wiring length when connecting the secondary electrode of the piezoelectric transformer to the cathode or anode of the discharge tube, and to reduce the leakage of electric power due to the floating capacitance of the wiring. As a result, the discharge tube can be operated efficiently.

  According to one aspect of the present invention, a piezoelectric transformer having a U-shaped cross section perpendicular to the length direction is used for an inverter that drives a discharge tube.

  As a result, the piezoelectric transformer can be used as a lamp holder, and the wiring length when the secondary electrode of the piezoelectric transformer is connected to the cathode or anode of the discharge tube can be shortened. The emitted light can be used efficiently and the power consumption of the discharge tube can be reduced.

  As described above, according to the present invention, by boosting the inside of the discharge tube, it is possible to discharge the discharge tube simply by inputting a low voltage to the discharge tube. It is possible to operate efficiently.

  In addition, according to one aspect of the present invention, by generating a drive signal for driving the boosting means inside the discharge tube, it is possible to discharge the discharge tube simply by inputting a DC low voltage to the discharge tube. As a result, the discharge tube can be operated more efficiently.

  Further, according to one embodiment of the present invention, by using a cold cathode tube as a discharge tube, it can be effectively used as a backlight for a liquid crystal display or the like, and the liquid crystal display can be reduced in size, weight, and power consumption. Can be achieved.

  In addition, according to one aspect of the present invention, by using a piezoelectric transformer as a boosting unit, it is possible to easily obtain a high boosting ratio and to easily reduce the size and weight. Even when the means is provided inside the discharge tube, it is possible to prevent an increase in the size of the discharge tube.

  In addition, according to one aspect of the present invention, an AC high voltage can be easily obtained inside a discharge tube simply by inputting an AC low voltage to the discharge tube by enclosing the piezoelectric transformer inside the discharge tube. As a result, the power consumption of the discharge tube can be reduced.

  In addition, according to one aspect of the present invention, by holding the piezoelectric transformer at the node of vibration, it is possible to prevent the output voltage of the piezoelectric transformer from being lowered even when the piezoelectric transformer is held inside the discharge tube. Can do.

  In addition, according to one aspect of the present invention, it is possible to discharge the discharge tube only by inputting a DC low voltage to the discharge tube by enclosing the drive circuit for driving the piezoelectric transformer inside the discharge tube. Thus, it becomes possible to further reduce the power consumption of the discharge tube.

  In addition, according to one aspect of the present invention, it is possible to further reduce the size, weight, and efficiency of the discharge tube by forming a drive circuit pattern on the piezoelectric transformer.

  In addition, according to one aspect of the present invention, the step-up ratio of the piezoelectric transformer is reduced due to fluctuations in the operating state of the piezoelectric transformer by changing the driving conditions of the piezoelectric transformer based on the actual driving characteristics of the piezoelectric transformer. This can be prevented.

  Further, according to one aspect of the present invention, by changing the oscillation frequency of the oscillation circuit according to the fluctuation of the resonance frequency of the piezoelectric transformer, the resonance characteristics of the piezoelectric transformer can be changed due to fluctuations in the drive signal level, temperature, load, and the like. Even in the case of change, the piezoelectric transformer can be driven at an optimum frequency, and the piezoelectric transformer can be operated efficiently.

  Further, according to one aspect of the present invention, by making the secondary electrode of the piezoelectric transformer also serve as the cathode or anode of the discharge tube, it is possible to omit at least one of the cathode or anode of the discharge tube. It is possible to reduce power consumption and reduce the size and weight.

  In addition, according to one aspect of the present invention, by making the length of the piezoelectric substrate substantially equal to the length of the discharge tube, it becomes possible to eliminate the need for high-voltage wiring, so that the discharge tube can be operated efficiently. It becomes possible.

  Also, according to one aspect of the present invention, the anode piezoelectric transformer and the cathode piezoelectric transformer, which are provided separately, are driven by alternating voltages whose phases are opposite to each other. It is possible to further increase the potential difference between and, and to discharge more efficiently.

  In addition, according to one aspect of the present invention, the discharge tube can be reduced in size and driven by enclosing the secondary electrode inside the discharge tube and taking the primary electrode out of the discharge tube. Even when the circuit is provided on the piezoelectric substrate, the drive circuit can be taken out of the discharge tube, and the influence of the discharge on the drive circuit can be eliminated.

  Further, according to one aspect of the present invention, when the length of the piezoelectric transformer provided in the inverter is made substantially equal to the length of the discharge tube, the secondary electrode of the piezoelectric transformer is connected to the cathode or anode of the discharge tube. Therefore, the length of the wiring can be shortened, and the discharge tube can be operated efficiently.

  According to one aspect of the present invention, the piezoelectric transformer can be used as a lamp holder by making the cross section perpendicular to the length direction of the piezoelectric transformer provided in the inverter into a U shape. It is possible to shorten the wiring length when connecting the secondary electrode of the piezoelectric transformer to the cathode or anode of the discharge tube, and it is possible to efficiently use the light radiated from the discharge tube. Power consumption can be reduced.

  Hereinafter, the functional configuration of the discharge tube according to the first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a functional configuration of a discharge tube according to a first embodiment of the present invention.
The discharge tube according to the first embodiment boosts the voltage input to the discharge tube inside the discharge tube.

  In FIG. 1, a booster 2 and a discharger 3 are provided inside the discharge tube 1. When a voltage is input to the discharge tube 1, the booster 2 boosts the voltage input to the discharge tube 1 and supplies the boosted voltage to the discharge unit 3, thereby discharging the discharge tube 1. .

  Here, the discharge tube 1 is, for example, a cold cathode tube, and the booster 2 is, for example, a piezoelectric transformer. The discharge tube 1 may be a hot cathode tube such as a fluorescent lamp, a mercury lamp, a metal halide lamp, a sodium lamp, a xenon lamp, or the like, and the booster 2 may be an electromagnetic conversion transformer.

  Thus, by providing the boosting means 2 inside the discharge tube 1, it is possible to discharge the discharge tube simply by inputting a low voltage to the discharge tube, and there is no need to provide high-voltage wiring in the discharge tube. Therefore, it is possible to reduce power consumption when lighting the discharge tube.

  Next, a functional configuration of the discharge tube according to the second embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing a functional configuration of a discharge tube according to the second embodiment of the present invention.
The discharge tube according to the second embodiment boosts the voltage input to the discharge tube inside the discharge tube and can generate a drive signal for driving the discharge tube inside the discharge tube.

  In FIG. 2, driving means 12, boosting means 13, and discharging means 14 are provided inside the discharge tube 11. When a voltage is input to the discharge tube 11, the driving unit 12 generates a signal for driving the boosting unit 13 based on the voltage input to the discharge tube 11. The signal generated by the driving unit 12 is boosted by the boosting unit 13 and the boosted signal is supplied to the discharging unit 13 to discharge the discharge tube 11.

  Here, the discharge tube 11 is, for example, a cold cathode tube, the driving unit 12 is, for example, an oscillation circuit, and the boosting unit 13 is, for example, a piezoelectric transformer.

  Thus, by providing the driving means 12 and the boosting means 13 inside the discharge tube 11, it becomes possible to discharge the discharge tube simply by inputting a DC voltage to the discharge tube, and supply an AC voltage to the discharge tube. Therefore, it is possible to eliminate the leakage of electric power to the outside through the electrostatic stray capacitance, and it is possible to further reduce the power consumption when the discharge tube is turned on.

  Next, a discharge device according to a third embodiment of the present invention will be described with reference to the drawings.

  FIG. 3 is a diagram showing a schematic configuration of a discharge device according to a third embodiment of the present invention. In the discharge device according to the third embodiment, a piezoelectric transformer is provided inside the cold cathode tube so that a voltage necessary for discharging the cold cathode tube can be obtained inside the discharge tube.

  In FIG. 3, inside the cold cathode tube 23 are a discharge gas, a piezoelectric substrate 24, primary electrodes 25 and 26 for driving the piezoelectric substrate 24, a secondary electrode 27 for outputting a voltage generated at the piezoelectric substrate 24, and a cathode 28. The secondary electrode 27 and the cathode 28 are held so as to face each other at a predetermined distance. Here, the DC power source 21 is connected to the input side of the drive circuit 22, the primary electrode 25 is connected to one end on the output side of the drive circuit 22, and the other end on the output side of the drive circuit 22 is connected. The primary electrode 26, the cathode 28, and the grounding point of the piezoelectric substrate 24 are connected.

  When the DC power supply 21 supplies a DC voltage of about 10 V to the drive circuit 22, the drive circuit 22 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 25. When an AC voltage is input between the primary electrode 25 and the primary electrode 26, the piezoelectric substrate 24 boosts this AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode 27.

  The secondary electrode 27 also serves as the anode of the cold cathode tube 23, and an AC high voltage of about 1200 V is generated between the secondary electrode 27 and the cathode 28 at about 40-60 KHz due to the boosting action of the piezoelectric transformer. Therefore, a discharge occurs in the cold cathode tube 23, and ultraviolet rays are emitted from the mercury vapor sealed in the cold cathode tube 23. The ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 23 to cause the cold cathode tube 23 to emit light.

  FIG. 4 is a perspective view showing a specific configuration example of the cold cathode tube 23 of FIG.

  In FIG. 4, a pair of primary electrodes 33 and 34 are formed on the upper and lower surfaces of one half of a rectangular plate-shaped piezoelectric substrate 32, and a secondary electrode 35 is formed on one end surface of the remaining half of the piezoelectric substrate 32. ing. The primary electrode 33 is provided with a lead wire 36 and the primary electrode 34 is provided with a lead wire 37, and the lead wires 36 and 37 are fixed at one end of the cold cathode tube 31, thereby Further, the piezoelectric substrate 32 is held. The cathode 38 is held at the other end of the cold cathode tube 31 by a lead wire 39, and the secondary electrode 35 of the piezoelectric substrate 32 and the cathode 38 are disposed to face each other, whereby the secondary electrode of the piezoelectric substrate 32 is disposed. 35 also serves as the anode of the cold cathode tube 31.

  Therefore, the discharge in the cold cathode tube 31 is performed between the secondary electrode 35 and the cathode 38 of the piezoelectric substrate 32, and when the piezoelectric transformer is provided in the cold cathode tube 31, The existing anode can be omitted, and the cold cathode tube 31 can be reduced in size and weight.

  Here, when the lead wires 36 and 37 are elongated, and the lead wires 36 and 37 can bend following the vibration of the piezoelectric substrate 32, the lead wires 36 and 37 hold the piezoelectric substrate 32. The influence on the vibration of the piezoelectric substrate 32 may be suppressed. In addition, the influence on the vibration of the piezoelectric substrate 32 can be suppressed by forming the lead wires 36 and 37 into a spring shape.

  FIG. 5 is a diagram for explaining a vibration mode of the piezoelectric transformer according to one embodiment of the present invention.

  In FIG. 5A, the piezoelectric substrate 32 is formed in a rectangular plate shape having a length of 2L, a width of W, and a thickness of T, and one side half of the piezoelectric substrate 32 is polarized P1 in the thickness direction. The other half of 32 is polarized P2 in the length direction. A pair of primary electrodes 33 and 34 are provided on the upper and lower surfaces of one half of the piezoelectric substrate 32 to which the polarization P1 is applied, and the other half of the piezoelectric substrate 32 to which the polarization P2 is applied is provided on one end surface in the longitudinal direction. Is provided with a secondary electrode 35.

  Here, as a material of the piezoelectric substrate 32, a piezoelectric crystal material, a piezoelectric ceramic material, or the like can be used. As the piezoelectric crystal material, for example, lithium niobate can be used, and as the piezoelectric ceramic material, for example, Barium titanate (BaTiO3) ceramics, lead titanate (PbTiO3) ceramics, lead zirconate titanate (PZT) ceramics, ternary ceramics, and the like can be used.

  When an input voltage V1 having a natural resonance frequency determined by the length 2L of the piezoelectric substrate 32 is input to the primary electrodes 33 and 34, mechanical vibration is generated due to the electrostrictive effect of the piezoelectric substrate 32. This mechanical vibration increases in the length direction, and an AC high voltage output voltage V2 is generated at the secondary electrode 35 due to the piezoelectric effect. That is, in the piezoelectric transformer, the electric energy is converted into mechanical vibration, the mechanical vibration is increased, and then the pressure is raised by returning to the electric energy.

  As shown in FIGS. 5B to 5D, there are λ (full wavelength vibration) mode, λ / 2 (half wavelength vibration) mode, 3λ / 2 mode, etc., as shown in FIGS. Correspondingly, the vibration displacement distribution is different. In each mode, there is a node where the amplitude of vibration is zero or minimal. For this reason, in order to operate the piezoelectric transformer efficiently, it is necessary to support the piezoelectric transformer at the node of vibration.

The boost ratio V2 / V1 at the time of no load at the output end is
V2 / V1 = 4 / π2, Qm, k31, k33, L / T (1)
Given in.

  Here, Qm is a mechanical quality factor, and k31 and k33 are piezoelectric constants.

The basic resonance frequency fr is
fr = c / (4L) (2)
Given in.

  Here, c is the speed of sound in the piezoelectric substrate 32.

  For example, when a lead zirconate titanate ceramic is used for the piezoelectric substrate 32, it is possible to obtain a step-up ratio V2 / V1 of several hundred times.

  Thus, by providing the piezoelectric transformer inside the cold cathode tube 23, it is possible to easily obtain an AC high voltage inside the cold cathode tube 23 simply by inputting an AC voltage to the cold cathode tube 23. The power consumption of the cold cathode tube 23 can be reduced and the increase in the size of the cold cathode tube 23 can be suppressed, and the cold cathode tube 23 is used as a backlight for a liquid crystal display or the like. Even in this case, low power consumption can be achieved without impairing the reduction in size and weight of the liquid crystal display.

  FIG. 6 is a block diagram showing a more specific first configuration example of the discharge device of FIG.

  In FIG. 6, a piezoelectric transformer 45 is provided in the cold cathode tube 44, the anode 46 of the cold cathode tube 44 is connected to the secondary electrode of the piezoelectric transformer 45, and the cathode 47 of the cold cathode tube 44 is grounded. The output terminal of the oscillator 42 is connected to one primary electrode of the piezoelectric transformer 45, and the other primary electrode of the piezoelectric transformer 45 is grounded. A part of the output from the piezoelectric transformer 45 is fed back to the oscillator 42 via the feedback circuit 43. Based on the feedback signal from the feedback circuit 43, the oscillator 42 adjusts the output from the oscillator 42 so that the piezoelectric transformer 45 is operated under optimum conditions.

  When a DC voltage is input to the DC voltage input terminal 41, the oscillator 42 operates and supplies an AC voltage having a predetermined frequency to the piezoelectric transformer 45. The piezoelectric transformer 45 boosts the alternating voltage output from the oscillator 42 and supplies it to the anode 46. When an AC high voltage is applied between the anode 46 and the cathode 47 by the piezoelectric transformer 45, a discharge occurs in the cold cathode tube 44, and ultraviolet rays are radiated from mercury vapor sealed in the cold cathode tube 44. The ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 44 to cause the cold cathode tube 44 to emit light.

  Here, the output characteristics of the piezoelectric transformer 45 differ between when the load is applied and when the load is not applied. When the piezoelectric transformer 45 is driven in accordance with the absence of the load, the output voltage decreases when the load is applied. A part of the output from the piezoelectric transformer 45 is fed back to the oscillator 42 so that the oscillation state of the oscillator 42 is changed so that the piezoelectric transformer 45 can be operated most efficiently.

  In this way, by feeding back a part of the output of the piezoelectric transformer 45 to the oscillator 42, it becomes possible to change the driving conditions of the piezoelectric transformer 45 based on the characteristics of the piezoelectric transformer 45 during actual driving. It is possible to prevent the step-up ratio of the piezoelectric transformer 45 from being lowered due to fluctuations in the operating state of 45.

  FIG. 7 is a block diagram showing a more specific second configuration example of the discharging apparatus of FIG.

  In FIG. 7, a variable oscillation circuit 51, a switching circuit 52, and a power amplification circuit 53 are connected in cascade, and a piezoelectric transformer 55 is provided in a cold cathode tube 54. The anode 56 of the cold cathode tube 54 is connected to the secondary electrode of the piezoelectric transformer 55, and the cathode 57 of the cold cathode tube 54 is grounded via a resistor 58. The output terminal of the power amplifier circuit 53 is connected to one primary electrode of the piezoelectric transformer 55, and the other primary electrode of the piezoelectric transformer 55 is grounded. The input terminal of the current detection circuit 59 is connected between the cathode 57 of the cold cathode tube 54 and the resistor 58, and the output from the brightness setting unit 60 and the output from the current detection circuit 59 are input to the comparison circuit 61. The output from the comparison circuit 61 is input to the drive range control circuit 62. The output of the drive range control circuit 62 is input to the variable oscillation circuit 51 and controls the oscillation frequency of the variable oscillation circuit 51.

  When the AC voltage from the variable oscillation circuit 51 is supplied to the piezoelectric transformer 55 via the switching circuit 52 and the power amplification circuit 53, the piezoelectric transformer 56 boosts the AC voltage output from the variable oscillation circuit 51, and the cold cathode Supply to the anode 56 of the tube 54. When an AC high voltage is applied between the anode 56 and the cathode 57 by the piezoelectric transformer 56, discharge occurs in the cold cathode tube 54, and ultraviolet rays are radiated from mercury vapor sealed in the cold cathode tube 54. This ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 54 and causes the cold cathode tube 54 to emit light.

Here, the resonance characteristics of the piezoelectric transformer 55 change due to fluctuations in the drive signal level, temperature, load, and the like. That is, as the drive signal level increases, the non-linearity and resonance resistance increase, and the resonance frequency and mechanical quality factor Qm decrease. Further, when the drive signal level increases, the temperature of the piezoelectric transformer 55 rises, and these phenomena are accelerated. The step-up ratio of the piezoelectric transformer 55 is
Although it is high at the resonance frequency, it becomes low as it goes away from the resonance frequency, and is proportional to the value of the mechanical quality factor Qm as shown in the equation (1).

  Therefore, the current detection circuit 59 detects the current flowing through the cold cathode tube 54, and the drive range control circuit 62 controls the oscillation frequency of the variable oscillation circuit 51 so that the current flowing through the cold cathode tube 54 is constant. . Even when the resonance characteristics of the piezoelectric transformer change due to fluctuations in the drive signal level, temperature, load, etc., the piezoelectric transformer is driven at an optimum frequency so that the piezoelectric transformer can be operated efficiently. .

FIG. 8 is a perspective view showing a schematic configuration of a cold cathode tube according to a fourth embodiment of the present invention.
The fourth embodiment shows an example of a method of holding a piezoelectric transformer in a cold cathode tube, and the piezoelectric transformer is held at a vibration node.

  In FIG. 8, a pair of primary electrodes 73 and 74 are formed on the upper and lower surfaces of one half of a rectangular plate-shaped piezoelectric substrate 72, and a secondary electrode 75 is formed on one end surface of the remaining half of the piezoelectric substrate 72. ing. The primary electrode 73 is provided with a lead wire 76, and the primary electrode 74 is provided with a lead wire 77, and the lead wires 76 and 77 are made of a flexible material or configuration so as not to affect the vibration of the piezoelectric substrate 72. And The piezoelectric substrate 72 is supported by the holding portions 80 and 81, and the holding portions 80 and 81 are fixed at one end of the cold cathode tube 71 so that the piezoelectric substrate 72 is held in the cold cathode tube 71.

  Here, the holding units 80 and 81 support the piezoelectric substrate 72 at the vibration node of the piezoelectric substrate 72 so as not to affect the vibration of the piezoelectric substrate 72. The holding parts 80 and 81 are preferably made of an insulator such as glass or plastic. Moreover, you may make it support a piezoelectric substrate in three or more places. The cathode 78 of the piezoelectric substrate 72 is held at the other end of the cold cathode tube 71 by a lead wire 79, the secondary electrode 75 of the piezoelectric substrate 72 and the cathode 78 are disposed facing each other, and the secondary electrode 75 of the piezoelectric substrate 72 is disposed. Doubles as the anode of the cold cathode tube 71. For this reason, the discharge in the cold cathode tube 71 is performed between the secondary electrode 75 and the cathode 78 of the piezoelectric substrate 72, and by omitting the anode originally present in the cold cathode tube 71, 71 can be reduced in size and weight.

  Thus, by holding the piezoelectric transformer at the vibration node, the piezoelectric transformer can be held inside the cold cathode tube 71 without lowering the output voltage of the piezoelectric transformer. Boosting can be performed efficiently.

  In addition to supporting the piezoelectric substrate 72 from the upper and lower surface directions of the piezoelectric substrate 72, the piezoelectric substrate 72 may be supported from the side surface direction of the piezoelectric substrate 72.

  FIG. 9 is a diagram showing a schematic configuration of a cold cathode tube according to a fifth embodiment of the present invention. In the fifth embodiment, a drive circuit for driving a piezoelectric transformer is enclosed in a cold cathode tube.

  In FIG. 9, a cold cathode tube 93 includes a drive circuit 92, a piezoelectric substrate 94, primary electrodes 95 and 96 that drive the piezoelectric substrate 94, a secondary electrode 97 that outputs a voltage generated on the piezoelectric substrate 94, and a cathode. 98 is sealed together with the discharge gas, and the secondary electrode 97 and the cathode 98 are held so as to face each other at a predetermined distance. Here, a DC power source 91 is connected to the input side of the drive circuit 92, a primary electrode 95 is connected to one end on the output side of the drive circuit 92, and the other end on the output side of the drive circuit 92 is connected to the other end. The primary electrode 96, the cathode 98, and the ground point of the piezoelectric substrate 94 are connected.

  When the DC power supply 91 supplies a DC voltage of about 10 V to the drive circuit 92, the drive circuit 92 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 95. When an AC voltage is input between the primary electrode 95 and the primary electrode 96, the piezoelectric substrate 94 boosts this AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode 97.

  The secondary electrode 97 also serves as the anode of the cold cathode tube 93, and an alternating high voltage of about 1200 V is generated between the secondary electrode 97 and the cathode 98 at about 40-60 KHz due to the boosting action of the piezoelectric transformer. Therefore, discharge occurs in the cold cathode tube 93, and ultraviolet rays are radiated from mercury vapor sealed in the cold cathode tube 93. This ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 93 to cause the cold cathode tube 93 to emit light.

  In this way, in addition to the piezoelectric transformer, a drive circuit 92 for driving the piezoelectric transformer is also provided in the cold cathode tube 93, so that a DC low voltage of about 10 V is simply applied to the cold cathode tube 93 from the DC power source 91. It is possible to obtain an AC high voltage of about 1200 V at about 40 to 60 KHz inside the cold cathode tube 93, and the cold cathode tube 93 can be discharged simply by inputting a DC low voltage to the cold cathode tube 93. Therefore, it is possible to further reduce power leakage to the outside when inputting a voltage to the cold cathode tube 93, and to further reduce the power consumption of the cold cathode tube 93.

  FIG. 10 is a perspective view showing a configuration example of the cold cathode tube of FIG.

  In FIG. 10, a pair of primary electrodes 103 and 104 are formed on the upper and lower surfaces of one half of a rectangular plate-shaped piezoelectric substrate 102, and a secondary electrode 105 is formed on one end surface of the other half of the piezoelectric substrate 102. ing. An IC chip 110 on which a circuit pattern 111 is formed is provided on the piezoelectric substrate 102, a lead wire 106 is connected to an input terminal of the IC chip 110, and an output terminal of the IC chip 110 is 1 by a wire line 112. Connected to the secondary electrode 103, the ground terminal of the IC chip 110 and the primary electrode 104 are connected to the lead wire 107.

  The piezoelectric substrate 102 and the IC chip 110 are held in the cold cathode tube 101 by fixing the lead wires 106 and 107 at one end of the cold cathode tube 101. Here, the circuit pattern 111 is configured to convert a DC voltage of about 10 V supplied via the lead wire 106 into an AC voltage of about 40 to 60 KHz and then output it to the primary electrode.

  Further, the cathode 108 is held at the other end of the cold cathode tube 101 by a lead wire 109, and the secondary electrode 105 of the piezoelectric substrate 102 is disposed so as to face the cathode 108 by arranging the secondary electrode 105 of the piezoelectric substrate 102 opposite to the cathode 108. Serves also as the anode of the cold cathode tube 101.

  When a DC voltage of about 10 V is supplied to the lead wire 106, the IC chip 110 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 103. When an AC voltage is input between the primary electrode 103 and the primary electrode 104, the piezoelectric substrate 102 boosts this AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode 105.

  For this reason, an alternating high voltage of about 1200 V at about 40-60 KHz is generated between the secondary electrode 105 and the cathode 108, discharge occurs in the cold cathode tube 101, and mercury vapor sealed in the cold cathode tube 101. Ultraviolet rays are emitted from. The ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 101 to cause the cold cathode tube 101 to emit light.

  Here, only a DC voltage of about 10 V is applied to the lead wire 106, and in addition to the fact that power leakage due to the floating capacitance from the lead wire 106 hardly occurs, the IC chip 110 is mounted on the piezoelectric substrate 102. Since it is possible to arrange the IC chip 110 close to the primary electrode 103, the wiring length of the AC voltage supplied from the IC chip 110 to the primary electrode 103 can be shortened. In addition, power leakage due to the floating capacitance of the wire 112 between the IC chip 110 and the primary electrode 103 can be suppressed to almost zero.

  Note that the circuit pattern 111 may be protected by covering the circuit pattern 111 on the IC chip 110 with a protective film such as a Si3N4 (silicon nitride) film, a PSG (phosphorus glass) film, or a polyimide film. The IC chip 110 may be molded with an epoxy resin, a silicon resin, or the like. Further, the circuit pattern 111 may be directly formed on the piezoelectric substrate 102 by an SOI (Silicon on Insulator) process or the like. Furthermore, a function of monitoring the output of the piezoelectric transformer may be integrated on the IC chip 110, and the driving conditions of the piezoelectric transformer may be changed in response to fluctuations in resonance characteristics during actual driving of the piezoelectric transformer.

FIG. 11 is a diagram showing a schematic configuration of a discharge device according to the sixth embodiment of the present invention.
In this sixth embodiment, a piezoelectric transformer is provided for each of the anode and cathode of the cold cathode tube, and the anode piezoelectric transformer and the cathode piezoelectric transformer are driven by AC voltages whose phases are opposite to each other. I have to.

  In FIG. 11, inside a cold cathode tube 123 are piezoelectric substrates 124 and 128, primary electrodes 125 and 126 that drive the piezoelectric substrate 124, a secondary electrode 127 that outputs a voltage generated at the piezoelectric substrate 124, and a piezoelectric substrate 128. Electrodes 129 and 130, a secondary electrode 131 that outputs a voltage generated at the piezoelectric substrate 128, and a discharge gas are sealed, and the secondary electrode 127 and the secondary electrode 131 face each other with a predetermined distance therebetween. So that it is held.

  Here, the DC power supply 121 is connected to the input side of the drive circuit 122, the primary electrode 125 is connected to the normal output terminal of the drive circuit 122, and the primary electrode is connected to the inverted output terminal of the drive circuit 122. 130 is connected, and the ground terminals of the drive circuit 22 are connected to the grounding points of the primary electrodes 126 and 129 and the piezoelectric substrates 124 and 128.

  When the DC power supply 121 supplies a DC voltage of about 10 V to the drive circuit 122, the drive circuit 122 converts this DC voltage into an AC voltage of about 40-60 KHz, and the first AC voltage and the first AC voltage of about 40-60 KHz. A second AC voltage having a phase opposite to that of the AC voltage is generated. The first AC voltage is output to the primary electrode 125, and the second AC voltage is output to the primary electrode 130.

  When the first AC voltage is input between the primary electrode 125 and the primary electrode 126, the piezoelectric substrate 124 boosts the first AC voltage to about 1200 V, and the boosted voltage is increased to the secondary electrode 127. Output to. When a second AC voltage is input between the primary electrode 129 and the primary electrode 130, the piezoelectric substrate 128 boosts the second AC voltage to about 1200 V, and the boosted voltage is increased to the secondary electrode 131. Output to.

  The secondary electrode 127 also serves as the anode of the cold cathode tube 123, and the secondary electrode 131 also serves as the cathode of the cold cathode tube 123. Then, by driving the piezoelectric substrate 124 and the piezoelectric substrate 128 with the first AC voltage and the second AC voltage whose phases are opposite to each other, an AC high voltage of about 2400 V is applied to the secondary electrode 127 and the secondary electrode. Since it occurs between the electrodes 131, discharge occurs in the cold cathode tube 123, and ultraviolet rays are radiated from mercury vapor sealed in the cold cathode tube 123. This ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 123 to cause the cold cathode tube 123 to emit light.

  Thus, by providing a piezoelectric transformer in each of the anode and the cathode of the cold cathode tube 123, while preventing leakage of electric power due to the floating electrostatic capacitance of the wiring, between the anode and the cathode of the cold cathode tube 123, The potential difference can be further increased, and the cold cathode tube 123 can be discharged more efficiently.

  FIG. 12 is a block diagram illustrating a configuration example of the drive circuit of FIG.

  12, the output terminal of the oscillation circuit 141 is connected to the clock terminal of the flip-flop 142, the normal output terminal of the flip-flop 142 is connected to the drive circuits 143 and 146, and the inverted output terminal of the flip-flop 142 is the drive circuit 144. , The drive circuits 143 and 144 drive the piezoelectric element 147, and the drive circuits 145 and 146 drive the piezoelectric element 148.

For this reason, the piezoelectric element 147 and the piezoelectric element 148 are driven with voltages having phases opposite to each other, and the voltage generated between the piezoelectric element 147 and the piezoelectric element 148 is only one of the piezoelectric element 147 or the piezoelectric element 148. The voltage can be doubled when boosted using.

  FIG. 13 is a perspective view showing a configuration example of the discharge tube of FIG.

  In FIG. 13, a pair of primary electrodes 153 and 154 are formed on the upper and lower surfaces of one half of a rectangular plate-shaped piezoelectric substrate 152, and a secondary electrode 155 is formed on one end surface of the remaining half of the piezoelectric substrate 152. ing. The primary electrode 153 is provided with a lead wire 156, and the primary electrode 154 is provided with a lead wire 157, and the lead wires 156 and 157 are fixed at one end of the cold cathode tube 151, whereby the inside of the cold cathode tube 151 is provided. In addition, the piezoelectric substrate 152 is held.

  Also, a pair of primary electrodes 159 and 160 are formed on the upper and lower surfaces of one half of the rectangular plate-shaped piezoelectric substrate 158, and a secondary electrode 161 is formed on one end surface of the remaining half of the piezoelectric substrate 158. . The primary electrode 159 is provided with a lead wire 162, and the primary electrode 160 is provided with a lead wire 163. By fixing the lead wires 162 and 163 at the other end of the cold cathode tube 151, the cold cathode tube 151 is provided. The piezoelectric substrate 158 is held inside.

  The secondary electrode 155 of the piezoelectric substrate 152 and the secondary electrode 161 of the piezoelectric substrate 158 are disposed to face each other. The secondary electrode 155 of the piezoelectric substrate 152 serves as the anode of the cold cathode tube 151 and 2 of the piezoelectric substrate 158. The next electrode 161 also serves as the cathode of the cold cathode tube 151.

  Therefore, the discharge in the cold cathode tube 151 is performed between the secondary electrode 155 of the piezoelectric substrate 152 and the secondary electrode 161 of the piezoelectric substrate 158, and the anode and cathode originally present in the cold cathode tube 151. The cold cathode tube 151 can be reduced in size and weight, and the secondary electrode 155 and the secondary electrode 161 are driven by driving the piezoelectric substrate 152 and the piezoelectric substrate 158 with voltages having phases opposite to each other. The voltage generated between the two can be doubled when boosted using only one piezoelectric transformer.

  When the secondary electrode 161 of the piezoelectric substrate 158 is used as the cathode of the cold cathode tube 151, tungsten or thorium may be used as the material of the secondary electrode 161, and Ba, Sr, Ca, Zr, etc. You may make it apply | coat the electron emission substance which consists of these oxides.

FIG. 14 is a diagram showing a schematic configuration of a discharge device according to the seventh embodiment of the present invention.
In the seventh embodiment, a piezoelectric transformer is provided for each of the anode and the cathode of the cold cathode tube, and the secondary node of the piezoelectric transformer is cooled by directly holding the vibration node of the piezoelectric transformer with the cold cathode tube. It is placed inside the cathode tube and the primary electrode of the piezoelectric transformer is taken out of the cold cathode tube.

  In FIG. 14, the piezoelectric substrate 174 is provided with primary electrodes 175 and 176 that drive the piezoelectric substrate 174, and a secondary electrode 177 that outputs a voltage generated at the piezoelectric substrate 174, and the piezoelectric substrate 178 includes the piezoelectric substrate 178. Primary electrodes 179 and 180, and a secondary electrode 181 that outputs a voltage generated at the piezoelectric substrate 178 are provided. Inside the cold cathode tube 173, the secondary electrode 177 and the piezoelectric substrate 178 of the piezoelectric substrate 174 are provided. A secondary electrode 181 and a discharge gas are enclosed.

  The cold cathode tube 173 holds the piezoelectric substrate 174 at the vibration node of the piezoelectric substrate 174, and holds the piezoelectric substrate 178 at the vibration node of the piezoelectric substrate 178. The secondary electrode 177 and the secondary electrode 178 are connected to each other. The cold cathode fluorescent lamps 173 are opposed to each other at a predetermined distance. Here, a DC power source 171 is connected to the input side of the drive circuit 172, a primary electrode 175 is connected to the normal output terminal of the drive circuit 172, and a primary electrode is connected to the inverted output terminal of the drive circuit 172. 180 is connected, and the ground terminals of the drive circuit 172 are connected to the grounding points of the primary electrodes 176 and 179 and the piezoelectric substrates 174 and 178.

  When the DC power supply 171 supplies a DC voltage of about 10 V to the drive circuit 172, the drive circuit 172 converts this DC voltage into an AC voltage of about 40-60 KHz, and the first AC voltage of about 40-60 KHz and the first A second AC voltage having a phase opposite to that of the AC voltage is generated. The first AC voltage is output to the primary electrode 175, and the second AC voltage is output to the primary electrode 180.

  When a first AC voltage is input between the primary electrode 175 and the primary electrode 176, the piezoelectric substrate 174 boosts the first AC voltage to about 1200 V, and the boosted voltage is increased to the secondary electrode 177. Output to. When a second AC voltage is input between the primary electrode 179 and the primary electrode 180, the piezoelectric substrate 178 boosts the second AC voltage to about 1200 V, and the boosted voltage is increased to the secondary electrode 181. Output to. At this time, since the piezoelectric substrates 174 and 178 are held at the nodes of vibration, boosting can be performed efficiently.

  The secondary electrode 177 also serves as the anode of the cold cathode tube 173, and the secondary electrode 181 also serves as the cathode of the cold cathode tube 173. Then, by driving the piezoelectric substrate 174 and the piezoelectric substrate 178 with the first AC voltage and the second AC voltage whose phases are opposite to each other, an AC high voltage of about 2400 V is applied to the secondary electrode 177 and the secondary electrode. Since it occurs between the electrodes 181, discharge occurs in the cold cathode tube 173, and ultraviolet rays are radiated from mercury vapor sealed in the cold cathode tube 173. The ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 173 to cause the cold cathode tube 173 to emit light.

  Thus, by providing a piezoelectric transformer in each of the anode and the cathode of the cold cathode tube 173 and holding the piezoelectric transformer at the node of vibration, it is possible to prevent the decrease in the step-up ratio of the piezoelectric transformer 173. The potential difference between the anode and the cathode can be increased, and the cold cathode tube 173 can be discharged more efficiently.

  Further, only the secondary electrodes 177 and 181 of the piezoelectric transformer are placed inside the cold cathode tube 173, and the primary electrodes 175, 176, 179 and 180 are taken out of the cold cathode tube 173, whereby the cold cathode tube 173 can be reduced in size. In addition, the drive circuit 172 can be provided on the piezoelectric substrates 174 and 178 with the drive circuit 172 outside the cold cathode tube 173, and the drive circuit 172 is affected by discharge. In addition, the wiring length between the drive circuit 172 and the primary electrodes 175 and 176 can be shortened.

  FIG. 15 is a perspective view showing a schematic configuration of the cold cathode tube of FIG.

  In FIG. 15, a pair of primary electrodes 193 and 194 are formed on the upper and lower surfaces of one half of a rectangular plate-shaped piezoelectric substrate 192, and a secondary electrode 195 is formed on one end surface of the remaining half of the piezoelectric substrate 192. ing. The primary electrode 193 is provided with a lead wire 196, and the primary electrode 194 is provided with a lead wire 197. By fixing the vibration node portion of the piezoelectric substrate 192 at one end of the cold cathode tube 191, The piezoelectric substrate 192 is held with the secondary electrode 195 entering the cathode tube 191 and the primary electrodes 193 and 194 protruding outside the cold cathode tube 191.

  In addition, a pair of primary electrodes 199 and 200 are formed on the upper and lower surfaces of one half of the rectangular plate-shaped piezoelectric substrate 198, and a secondary electrode 201 is formed on one end surface of the remaining half of the piezoelectric substrate 198. . The primary electrode 199 is provided with a lead wire 202, and the primary electrode 200 is provided with a lead wire 203. By fixing the vibration node of the piezoelectric substrate 198 at the other end of the cold cathode tube 191, The piezoelectric substrate 198 is held in a state in which the secondary electrode 201 enters the cold cathode tube 191 and the primary electrodes 199 and 200 protrude from the cold cathode tube 191.

  The secondary electrode 195 of the piezoelectric substrate 192 and the secondary electrode 201 of the piezoelectric substrate 198 are disposed to face each other in the cold cathode tube 191, and the secondary electrode 195 of the piezoelectric substrate 192 serves as the anode of the cold cathode tube 191. The secondary electrode 201 of the piezoelectric substrate 198 also serves as the cathode of the cold cathode tube 191.

  For this reason, the discharge in the cold cathode tube 191 is performed between the secondary electrode 195 of the piezoelectric substrate 192 and the secondary electrode 201 of the piezoelectric substrate 198, and the anode and cathode originally present in the cold cathode tube 191. Thus, the cold cathode tube 191 can be reduced in size and weight, and the piezoelectric substrate 192 and the piezoelectric substrate 198 are driven with voltages having phases opposite to each other, whereby the secondary electrode 195 and the secondary electrode 201 are driven. The voltage generated between the two can be doubled when boosted using only one piezoelectric transformer. Further, by holding the piezoelectric substrate 192 and the piezoelectric substrate 198 at the vibration node, it is possible to prevent the step-up ratio from being lowered, and the primary electrodes 193, 194, 199, and 200 are connected to the cold cathode tube 191. The cold cathode tube 191 can be further downsized by taking it out of the space.

  FIG. 16 is a diagram showing a schematic configuration of a discharge device according to the eighth embodiment of the present invention.

  In the eighth embodiment, the length of the piezoelectric substrate is made substantially equal to the length of the discharge tube.

  In FIG. 16, in the cold cathode tube 213, there are a piezoelectric substrate 214, primary electrodes 215 and 216 for driving the piezoelectric substrate 214, a cathode 217 and a secondary electrode 218 for outputting a voltage generated at the piezoelectric substrate 214 as a discharge gas. In addition, the length of the piezoelectric substrate 214 is set to be approximately equal to the length of the cold cathode tube 213 so that the cathode 217 and the secondary electrode 218 can be opposed to each other with a predetermined distance. ing. Here, a DC power supply 212 is connected to the input side of the drive circuit 211, a primary electrode 216 is connected to one end on the output side of the drive circuit 212, and the other end on the output side of the drive circuit 212 is connected to the other end. The primary electrode 215, the cathode 217, and the ground point of the piezoelectric substrate 214 are connected.

  When the DC power supply 211 supplies a DC voltage of about 10 V to the drive circuit 212, the drive circuit 212 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 216. When an AC voltage is input between the primary electrode 215 and the primary electrode 216, the piezoelectric substrate 214 boosts this AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode 218.

  The secondary electrode 218 also serves as the anode of the cold cathode tube 213, and an alternating high voltage of about 1200 V is generated between the cathode 217 and the secondary electrode 218 at about 40-60 KHz due to the boosting action of the piezoelectric transformer. Therefore, a discharge occurs in the cold cathode tube 213, and ultraviolet rays are emitted from mercury vapor sealed in the cold cathode tube 213. This ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 213 to cause the cold cathode tube 213 to emit light.

  Thus, by making the length of the piezoelectric substrate 214 approximately equal to the length of the cold cathode tube 213, the high-voltage wiring can be shortened. Leakage can be reduced, and the cold cathode tube 213 can be operated efficiently.

  FIG. 17 is a perspective view showing a schematic configuration of the cold cathode tube of FIG.

  In FIG. 17, a pair of primary electrodes 223 and 224 are formed on the upper and lower surfaces of one side of a rectangular plate-shaped piezoelectric substrate 222, and one end surface on the opposite side of the piezoelectric substrate 222 on which the primary electrodes 223 and 224 are formed. A secondary electrode 225 is formed on the. Then, by projecting the secondary electrode 225 from the end face of the piezoelectric substrate 222, the primary electrode 223 and the secondary electrode 225 can be opposed to each other via the piezoelectric substrate 222. The primary electrode 223 is provided with a lead wire 226 and the primary electrode 224 is provided with a lead wire 227. By fixing the lead wires 226 and 227 at one end of the cold cathode tube 221, the inside of the cold cathode tube 221 is provided. Further, the piezoelectric substrate 222 is held.

  Here, the primary electrode 223 also serves as the cathode of the cold cathode tube 221, and the secondary electrode 225 also serves as the anode of the cold cathode tube 221. For this reason, when an AC voltage is applied between the primary electrodes 223 and 224 via the lead wires 226 and 227, an AC high voltage is generated at the secondary electrode 225 due to the boosting action of the piezoelectric substrate 222. Discharge is performed between the secondary electrode 223 and the secondary electrode 225.

  Thus, by making the length of the piezoelectric substrate 222 substantially equal to the length of the cold cathode tube 221, the anode and the cathode originally present in the cold cathode tube 221 can be omitted, and the small and light weight of the cold cathode tube 221 can be omitted. In addition, since it is possible to eliminate the need for high-voltage wiring, it is possible to reduce the leakage of power to the outside due to the stray capacitance of the wiring and to operate the cold cathode tube 221 efficiently. It becomes possible to make it.

  FIG. 18 is a diagram showing a schematic configuration of a discharge device according to the ninth embodiment of the present invention.

  In the ninth embodiment, the length of the piezoelectric transformer is made substantially equal to the length of the cold cathode tube, and this piezoelectric transformer is used as an inverter for driving the cold cathode tube.

  In FIG. 18, the inverter 231 includes a drive circuit 233 and a piezoelectric transformer. Primary electrodes 235 and 236 that drive the piezoelectric substrate 234 and voltages generated by the piezoelectric substrate 234 are output to the piezoelectric substrate 234 constituting the piezoelectric transformer. The secondary electrode is provided so that the length of the piezoelectric substrate 234 is substantially equal to the length of the cold cathode tube 237. The primary electrode 236 of the piezoelectric substrate 234 is connected to the cathode 238 of the cold cathode tube 237 and the secondary electrode is connected to the anode 239 of the cold cathode tube 237.

  A DC power supply 232 is connected to the input side of the drive circuit 233, a primary electrode 235 is connected to one end on the output side of the drive circuit 233, and a primary is connected to the other end on the output side of the drive circuit 233. The grounding points of the electrode 236, the cathode 238, and the piezoelectric substrate 234 are connected. Here, since the length of the piezoelectric substrate 234 is substantially equal to the length of the cold cathode tube 237, the wiring length from the secondary electrode of the piezoelectric substrate 234 to the anode 239 of the cold cathode tube 237 can be shortened. .

  When the DC power supply 232 supplies a DC voltage of about 10 V to the drive circuit 233, the drive circuit 233 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 235. When an AC voltage is input between the primary electrode 235 and the primary electrode 236, the piezoelectric substrate 234 boosts the AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode.

  The voltage generated in the secondary electrode is output to the anode 239 of the cold cathode tube 237, and an AC high voltage of about 1200 V is generated between the cathode 238 and the anode 239 of the cold cathode tube 237 at about 40-60 KHz. Then, a discharge occurs in the cold cathode tube 237, and ultraviolet rays are radiated from mercury vapor sealed in the cold cathode tube 237. This ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 237 to cause the cold cathode tube 237 to emit light.

  In this way, by making the length of the piezoelectric substrate 234 provided in the inverter 231 substantially equal to the length of the cold cathode tube 237, an AC high voltage of about 1200 V is supplied to the cold cathode tube 237 at about 40-60 KHz. Therefore, it is possible to reduce the length of the wiring necessary for the operation, and to reduce the leakage of power to the outside due to the floating capacitance of the wiring, so that the cold cathode tube 237 can be operated efficiently. Is possible.

  FIG. 19 is a perspective view showing a schematic configuration of the discharge device of FIG.

  In FIG. 19, a pair of primary electrodes 244 and 245 are formed on the upper and lower surfaces of one side of a rectangular plate-shaped piezoelectric substrate 243, and one end surface on the opposite side of the piezoelectric substrate 243 on which the primary electrodes 244 and 245 are formed. Is formed with a secondary electrode 246, and the length L1 of the piezoelectric substrate 243 is substantially equal to the length L2 of the cold cathode tube 247. The primary electrode 244 of the piezoelectric substrate 243 is connected to the cathode 248 of the cold cathode tube 247, and the secondary electrode 246 is connected to the anode 249 of the cold cathode tube 247. A DC power supply 241 is connected to the input side of the drive circuit 242, a primary electrode 244 is connected to one end on the output side of the drive circuit 242, and a primary electrode is connected to the other end on the output side of the drive circuit 242. An electrode 245 and a cathode 248 are connected.

  When a DC voltage of about 10 V is supplied to the drive circuit 242, the drive circuit 242 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 244. When an AC voltage is input between the primary electrode 244 and the primary electrode 245, the piezoelectric substrate 243 boosts this AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode 246.

  The voltage generated in the secondary electrode 246 is output to the anode 249 of the cold cathode tube 247, and an AC high voltage of about 1200 V is generated between the cathode 248 and the anode 249 of the cold cathode tube 247 at about 40-60 KHz, Discharge occurs in the cold cathode tube 247.

  Thus, by making the length L1 of the piezoelectric substrate 243 substantially equal to the length L2 of the cold cathode tube 247, the wiring length between the secondary electrode 246 and the anode 249 can be shortened, and the wiring Since it is possible to reduce leakage of electric power to the outside due to stray capacitance or the like, the cold cathode tube 247 can be efficiently operated.

  FIG. 20 is a diagram showing a schematic configuration of a discharge device according to the tenth embodiment of the present invention.

  In the tenth embodiment, the cross section perpendicular to the longitudinal direction of the piezoelectric transformer is U-shaped, the piezoelectric transformer can be used as an inverter for driving the cold cathode tube, and the piezoelectric transformer is used as a cold cathode tube lamp. It can be used as a holder.

  In FIG. 20, a piezoelectric substrate 253 is provided with primary electrodes 254 and 255 for driving the piezoelectric substrate 253, and secondary electrodes for outputting a voltage generated at the piezoelectric substrate 253, and the length of the piezoelectric substrate 253 is set to a cold cathode tube. The cold cathode tube 256 can be inserted between the piezoelectric substrates 253 by making the section substantially equal to the length of 256 and U-shaped in a cross section perpendicular to the length direction. The primary electrode 255 of the piezoelectric substrate 253 is connected to the cathode 257 of the cold cathode tube 256, and the secondary electrode is connected to the anode 258 of the cold cathode tube 256. A DC power source 251 is connected to the input side of the drive circuit 252, a primary electrode 254 is connected to one end on the output side of the drive circuit 252, and a primary electrode is connected to the other end on the output side of the drive circuit 252. The grounding points of the electrode 255, the cathode 257, and the piezoelectric substrate 253 are connected. Here, since the length of the piezoelectric substrate 253 is substantially equal to the length of the cold cathode tube 256, the wiring length from the secondary electrode of the piezoelectric substrate 253 to the anode 258 of the cold cathode tube 256 can be shortened. In addition, since the piezoelectric substrate 253 is formed in a U shape, the piezoelectric substrate 253 can be used as a lamp holder.

  When the DC power supply 251 supplies a DC voltage of about 10 V to the drive circuit 252, the drive circuit 252 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 254. When an AC voltage is input between the primary electrode 254 and the primary electrode 255, the piezoelectric substrate 253 boosts the AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode.

  The voltage generated in the secondary electrode is output to the anode 258 of the cold cathode tube 256, and an AC high voltage of about 1200 V is generated between the cathode 257 and the anode 258 of the cold cathode tube 258 at about 40-60 KHz. Then, discharge occurs in the cold cathode tube 256, and ultraviolet rays are emitted from the mercury vapor sealed in the cold cathode tube 256. The ultraviolet light excites the phosphor applied on the inner surface of the cold cathode tube 256 to cause the cold cathode tube 256 to emit light.

  The light emitted from the cold cathode tube 256 is reflected by the inner surface of the piezoelectric substrate 253 because the piezoelectric substrate 253 is shaped so that the cross section perpendicular to the length direction is U-shaped, and the cold cathode tube The light emitted from 256 can be efficiently guided in a predetermined direction.

  As described above, the piezoelectric substrate 253 is formed so that the length of the piezoelectric substrate 253 is substantially equal to the length of the cold cathode tube 256 and the cross section perpendicular to the length direction is U-shaped. It is possible to shorten the length, and it is possible to efficiently guide light emitted from the cold cathode tube 256 in a predetermined direction, and the cold cathode tube 256 can be operated efficiently.

  FIG. 21 is a perspective view showing a schematic configuration of the discharging device of FIG.

  In FIG. 21, the piezoelectric substrate 263 is shaped so that the cross section perpendicular to the length direction is U-shaped, and a pair of primary electrodes 264 and 265 are formed on the inner and outer surfaces of one side of the piezoelectric substrate 263. A secondary electrode 266 is formed on one end surface of the piezoelectric substrate 263 on which the primary electrodes 264 and 265 are formed. The cold cathode tube 267 is held inside the U-shaped cross section of the piezoelectric substrate 263, the primary electrode 264 of the piezoelectric substrate 263 is connected to the cathode 268 of the cold cathode tube 267, and the secondary electrode 266 is the cold cathode tube 267. Connected to the anode 269. A DC power supply 261 is connected to the input side of the drive circuit 262, a primary electrode 265 is connected to one end on the output side of the drive circuit 262, and a primary electrode is connected to the other end on the output side of the drive circuit 262. An electrode 264 and a cathode 268 are connected.

  When a DC voltage of about 10 V is supplied to the drive circuit 262, the drive circuit 262 converts this DC voltage into an AC voltage of about 40-60 KHz and outputs it to the primary electrode 265. When an AC voltage is input between the primary electrode 264 and the primary electrode 265, the piezoelectric substrate 263 boosts this AC voltage to about 1200 V and outputs the boosted voltage to the secondary electrode 266.

  The voltage generated in the secondary electrode 266 is output to the anode 269 of the cold cathode tube 267, and an AC high voltage of about 1200 V is generated between the cathode 268 and the anode 269 of the cold cathode tube 267 at about 40-60 KHz, Discharge occurs in the cold cathode tube 267. Due to this discharge, light is emitted from the cold cathode fluorescent lamp 267. The light emitted from the cold cathode tube 267 is reflected by the inner surface of the piezoelectric substrate 263 and emitted in a predetermined direction. Therefore, when the cold cathode tube 267 is used as a backlight for a liquid crystal display or the like, the piezoelectric substrate 263 can be effectively used as a lamp holder for the liquid crystal display.

  Thus, by forming the piezoelectric substrate 263 so that the cross section perpendicular to the length direction is U-shaped, it becomes possible to efficiently guide the light emitted from the cold cathode tube 267 in a predetermined direction, Since the piezoelectric transformer can also be used as a lamp holder, the apparatus can be reduced in size and weight.

  Note that the light emitted from the cold cathode tube 267 may be more efficiently reflected by attaching a reflective film inside the piezoelectric substrate 263.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various other modifications can be made within the scope of the technical idea of the present invention. For example, in the above-described embodiments, the case where the piezoelectric transformer is provided inside the discharge tube has been described. However, any electron tube that requires a high voltage may be used, and the cathode ray tube is operated by providing the piezoelectric transformer inside the cathode ray tube. Therefore, a high voltage necessary for this purpose may be generated inside the cathode ray tube.

It is a block diagram which shows the functional structure of the discharge tube concerning 1st Example of this invention. It is a block diagram which shows the functional structure of the discharge tube concerning 2nd Example of this invention. It is a figure which shows schematic structure of the discharge device concerning 3rd Example of this invention. It is a perspective view which shows the structural example of the cold cathode tube of FIG. It is a figure explaining the vibration mode of the piezoelectric transformer concerning one Example of this invention. It is a block diagram which shows the 1st structural example of the discharge device of FIG. It is a block diagram which shows the 2nd structural example of the discharge device of FIG. It is a perspective view which shows schematic structure of the cold cathode tube concerning 4th Example of this invention. It is a figure which shows schematic structure of the cold cathode tube concerning 5th Example of this invention. FIG. 10 is a perspective view illustrating a configuration example of the cold cathode tube in FIG. 9. It is a figure which shows schematic structure of the discharge device concerning 6th Example of this invention. FIG. 12 is a block diagram illustrating a configuration example of a drive circuit in FIG. 11. It is a perspective view which shows the structural example of the discharge tube of FIG. It is a figure which shows schematic structure of the discharge device concerning 7th Example of this invention. It is a perspective view which shows schematic structure of the cold cathode tube of FIG. It is a figure which shows schematic structure of the discharge device concerning the 8th Example of this invention. It is a perspective view which shows schematic structure of the cold cathode tube of FIG. It is a figure which shows schematic structure of the discharge device concerning 9th Example of this invention. It is a perspective view which shows schematic structure of the discharge device of FIG. It is a figure which shows schematic structure of the discharge device concerning 10th Example of this invention. It is a perspective view which shows schematic structure of the discharge device of FIG. It is a figure which shows schematic structure of the conventional discharge device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Discharge tube 2,12 Boosting means 3,14 Discharge means 12 Drive means 21,91,121,171,211,232,241,251,261 DC power supply 22,92,122,172,212,233,242 , 252, 262 Drive circuit 23, 31, 44, 54, 71, 93, 101, 123151, 173, 191, 213, 221, 237, 247, 256, 267 Cold cathode tube 24, 32, 72, 94, 102, 124, 128, 152, 158, 174, 178, 192, 198, 214, 222, 234, 243, 253, 263 Piezoelectric substrate 25, 26, 33, 34, 73, 74, 95, 96, 103, 104, 125 126, 153, 154, 175, 176, 179, 180, 193, 194, 199, 200, 215, 21 6, 223, 224, 235, 236, 244, 245, 254, 255, 264, 265 Primary electrode 27, 35, 75, 97, 105, 127, 131, 155, 161, 177, 181, 195, 201, 218, 225, 246, 266 Secondary electrode 28, 38, 47, 57, 78, 98, 108, 238, 248, 257, 268 Cathode 46, 56, 217, 239, 249, 258, 269 Anode 36, 37, 39, 76, 77, 79, 106, 107, 109, 156, 157, 162, 163, 196, 197, 202, 203, 226, 227 Lead wire 41 Input terminal 42 Oscillator 43 Feedback circuit 45, 55 Piezoelectric transformer 51 Variable Oscillation circuit 52 Switching circuit 53 Power amplification circuit 58 Resistance 59 Current detection circuit 60 Brightness setting Part 61 comparison circuit 62 driving range control circuit 80 81 holding portion 110 IC chip 111 circuit pattern 112 wire line 141 oscillation circuit 142 flip-flop 143 to 146 drive circuit 147 and 148 piezoelectric element 231 inverter

Claims (6)

A cathode and an anode provided facing each other;
A piezoelectric transformer for transforming a voltage supplied to the anode or the cathode;
A discharge tube comprising holding means for holding the piezoelectric transformer therein.   The discharge tube according to claim 1, wherein the holding means holds the piezoelectric transformer at a vibration node.   The discharge tube according to claim 1 or 2, wherein the holding means encloses a drive circuit for driving the piezoelectric transformer.   4. The discharge tube according to claim 3, wherein a pattern of the drive circuit is formed on the piezoelectric transformer.   5. The discharge tube according to claim 3, wherein the drive circuit includes an oscillation circuit and a feedback circuit that feeds back an output of the piezoelectric transformer to the oscillation circuit.   The discharge tube according to claim 5, wherein the drive circuit changes an oscillation frequency of the oscillation circuit in accordance with a change in a resonance frequency of the piezoelectric transformer.

Images