JP2006259676A - Electron-emitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron-emitting apparatus which has a simple power supply and is capable of avoiding unnecessary power consumption thereof. <P>SOLUTION: An electron-emitting element 10 has; an electron emission unit EP including a lower electrode 12, an emitter section 13 composed of a dielectric material, and an upper electrodes 14 having a plurality of micro through holes; and a power supply 30 for applying a power supply voltage to the electron emission unit. During the period between the point at which emission of electrons accumulated in the emitter section is started and the point at which the electron emission is completed, the power supply generates a first power supply voltage AC 210(V) as power supply voltage, whose absolute value changes with forming a sinusoidal wave so that the potential of the upper electrode is higher than the potential of the lower electrode. During the period between the point at which the electron accumulation in the emitter section is started and the point at which the electron accumulation is completed, the power supply generates a second power supply voltage AC 50(V) as power supply voltage whose absolute value increases with forming a sinusoidal wave so that the potential of the lower electrode is higher than the potential of the upper electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides an element comprising an emitter portion made of a dielectric, a lower electrode formed below the emitter portion, and an upper electrode formed above the emitter portion and formed with a plurality of fine through holes. The present invention relates to an electron emission device that emits electrons accumulated in an emitter portion through a fine through hole by applying a voltage.

Conventionally, an emitter portion made of a dielectric, a lower electrode formed on the lower surface of the emitter portion, and an upper electrode formed on the upper surface of the emitter portion and having a number of fine through holes, the upper electrode and the lower electrode are provided. Electron emission that emits electrons through the fine through-holes in the upper electrode by applying a driving voltage (voltage pulse) Vin between the electrodes (hereinafter referred to as “between upper and lower electrodes”) to invert the polarization of the dielectric. Devices are known (see, for example, Patent Document 1 and Patent Document 2). Such an electron-emitting device is applied, for example, to an element constituting a display pixel that emits light by irradiating electrons to a phosphor. Further, in the following documents (Non-Patent Documents 1 to 3), various theories relating to the emission of electrons from an emitter formed of a dielectric are described.
Japanese Patent No. 3160213 (Claims 1, paragraphs 0016 to 0019, FIGS. 2 and 3) US Pat. No. 5,874,802 Yasuoka, Ishii, "Pulsed electron source using a ferroelectric cathode" Applied Physics Vol.68, No.5, p546-550 (1999) VFPuchkarev, GAMesyats, On the mechanism of emission from the ferroelectric ceramic cathode, J.Appl.Phys., Vol 78, No. 9, 1 November, 1995, p.5633-5637 H.Riege, Electron emissionferroelectrics-a review, Nuc1. Instr. And Meth.A340, p. 80-89 (1994)

  Control for emitting electrons from the electron-emitting device is executed as shown in FIG. That is, the electron-emitting device applies a constant voltage Vm for making the potential of the lower electrode higher than the potential of the upper electrode from time t10 to time t20 as the driving voltage Vin. As a result, the direction of the dipole of the emitter portion is reversed (negative-side polarization is reversed), so that electrons are supplied from the upper electrode toward the emitter portion. As a result, electrons are accumulated mainly near the upper portion of the emitter section 13.

  Next, from time t20 to time t30, the electron-emitting device applies a constant voltage Vp for making the upper electrode potential higher than the lower electrode potential as the drive voltage Vin between the upper and lower electrodes. As a result, the polarization of the emitter portion is reversed again (positive-side polarization reversal), and the electrons accumulated in the vicinity of the upper portion of the emitter portion are released upward through the fine through hole of the upper electrode due to the repulsive force of Coulomb. The Therefore, in an apparatus in which a phosphor is disposed so as to face the upper electrode, the phosphor is irradiated with electrons and the phosphor emits light.

  The electron emission device repeats such an operation. That is, the electron-emitting device again applies a constant voltage Vm between the upper and lower electrodes to make the potential of the lower electrode higher than the potential of the upper electrode at time t30. At time t40, a constant voltage Vp for making the potential of the upper electrode higher than the potential of the lower electrode is applied between the upper and lower electrodes, and electron emission (light emission) is performed again. As described above, the electron emission device repeatedly accumulates and emits electrons by applying a rectangular wave pulse between the upper and lower electrodes.

  However, since the electron-emitting device is a capacitive device including a resistance component and a dielectric loss, when the drive voltage Vin that changes stepwise as described above is applied between the upper and lower electrodes, most of the work to be performed by the power source is large. It is converted into heat by the Joule loss and dielectric loss of the element. In addition, when the protective resistance is connected in series to the electron-emitting device, even if the drive voltage Vin that changes stepwise as described above is applied between the upper and lower electrodes, it is defined by the potential of the upper electrode relative to the potential of the lower electrode. The actual voltage between the upper and lower electrodes (hereinafter referred to as “element end voltage Vka”) does not change immediately, and the element end voltage Vka gradually approaches the applied drive voltage Vin. Therefore, after the drive voltage Vin is switched from the constant voltage Vp to Vm or vice versa, the element and the resistance component in the vicinity of the element are equal to the constant voltage Vp or Vm to which the element end voltage Vka is applied. A large Joule heat is generated. As a result, there arises a problem that power is wasted or the element is overheated.

  In addition, as shown in FIG. 32, the inventor sets the constant voltage Vp immediately after the time t30 (at the time when the application of the constant voltage Vm is started in order to accumulate electrons) or at the time t40 (to discharge the electrons). It has been found that the electrons are emitted at an unscheduled timing and / or the electrons may be emitted excessively immediately after the application). In this case, if the electron-emitting device is used as a light-emitting device for display as described above, there arises a problem that light is emitted at an unscheduled timing or abnormal large light emission occurs.

The electron emission device of the present invention has been made in order to cope with the above-described problems, and its features are as follows:
An emitter portion made of a dielectric, a lower electrode formed at the lower portion of the emitter portion, a plurality of fine through holes formed at the upper portion of the emitter portion so as to face the lower electrode across the emitter portion And an upper electrode formed so that a surface of the fine through-hole and facing the emitter portion is spaced apart from the emitter portion by a predetermined distance. An electron emitter,
A power supply for generating a power supply voltage to be applied to the electron emission unit;
In an electron emission device that accumulates electrons in the emitter section by the power supply voltage and emits the accumulated electrons through the fine through hole,
The power supply is
From when the electron-emitting device is in a state of accumulating electrons in the emitter section until at least the amount of electrons emitted per unit time when electrons accumulated in the emitter section are emitted through the fine through-holes is maximized. Generating, as the power supply voltage, a first power supply voltage whose absolute value changes sinusoidally so that the potential of the upper electrode is higher than the potential of the lower electrode during the period,
The potential of the lower electrode is made higher than the potential of the upper electrode during a period from when the electron-emitting device is not accumulating electrons in the emitter portion to at least accumulation of electrons in the emitter portion. The second power supply voltage whose absolute value increases sinusoidally is generated as the power supply voltage.

  In this case, the electron emission unit may include a protective resistor connected in series to the electron emission element.

  According to this, the amount of electron emission per unit time from when the electron-emitting device is in a state of accumulating electrons in the emitter portion to when at least the electrons accumulated in the emitter portion are emitted through the fine through hole is maximized. During this period, a first power supply voltage whose absolute value changes sinusoidally so that the potential of the upper electrode is higher than the potential of the lower electrode is applied as a power supply voltage to the electron emission portion.

  Further, a sine wave shape is formed so that the potential of the lower electrode is higher than the potential of the upper electrode during a period from when the electron-emitting device is not accumulating electrons in the emitter portion to at least the accumulation of electrons in the emitter portion. A second power supply voltage whose absolute value increases is applied to the electron emission portion as a power supply voltage.

  Therefore, since the absolute value of the power supply voltage applied to the electron emission portion gradually increases in a sine wave form at both the start of electron accumulation and the start of electron emission, the element end voltage (potential difference between the upper and lower electrodes). The absolute value of increases gradually so as to follow the power supply voltage. As a result, since the difference between the power supply voltage applied to the electron emission portion and the element end voltage does not increase, the generation of Joule heat is small, and the amount of power consumed in vain can be reduced.

  In addition, since no large Joule heat is generated, the temperature of the electron-emitting device does not increase. Therefore, it can be avoided that the characteristics of the emitter section are changed by heat. Furthermore, since it is possible to avoid gasifying the substance adsorbed on the electron-emitting device, generation of plasma due to the gasified substance can be suppressed. As a result, excessive emission of electrons and damage to the electron-emitting device due to ion bombardment can be avoided.

  In addition, after the first power supply voltage for emitting electrons starts to be applied, the absolute value of the first power supply voltage gradually increases. Thereby, the magnitude of the inrush current flowing through the emitter section can be reduced, and the change rate of the element end voltage after completion of the positive side polarization reversal of the emitter section due to the application of the first power supply voltage can be reduced. As a result, unnecessary emission of electrons due to the inrush current (unnecessary light emission when a phosphor facing the upper electrode is provided as in a display device) or a rapid increase in device voltage immediately after completion of positive side polarization reversal. Unnecessary emission of electrons (unnecessary light emission) due to the change can be avoided.

  Furthermore, even after the second power supply voltage is applied to accumulate electrons and after the negative polarization inversion of the emitter section is completed, the absolute value of the second power supply voltage gradually increases. Accordingly, it is possible to prevent electron emission at an unnecessary timing presumed to be caused by a rapid change in the element end voltage after the negative side polarization reversal of the emitter section is completed.

  Note that “when the electron-emitting device is in a state where electrons are accumulated in the emitter portion” is not limited to the time point when the electron-emitting device completes the accumulation of electrons in the emitter portion, but for a while after the accumulation of electrons is completed. Of course, even after the passage of time. Furthermore, when the electron-emitting device is in a state where electrons are accumulated in the emitter section, it is not necessary that the maximum amount of electrons be accumulated in the emitter section. As long as it is stored in In addition, the “period until electrons are accumulated in the emitter portion” may be until the time point when the amount of electrons that can be emitted is accumulated.

  On the other hand, in such an electron-emitting device, the absolute value of the voltage necessary for accumulating the amount of electrons to be emitted in the emitter is from the emitter to the fine through hole of the upper electrode. It has a characteristic (polarization-element end voltage characteristic, that is, Q-V characteristic as shown in FIG. 7) that is smaller than the absolute value of the voltage required for emission. Therefore, if the amplitude of the first power supply voltage and the amplitude of the second power supply voltage are made the same, either the first power supply voltage or the second power supply voltage becomes larger than necessary, and power is wasted. Alternatively, any voltage becomes smaller than necessary, and a desired amount of electrons cannot be emitted.

  From the above, it is preferable that the amplitude of the first power supply voltage is larger than the amplitude of the second power supply voltage.

Furthermore, the power source is
It is desirable to provide a switching element that switches an application state of the first power supply voltage and the second power supply voltage to the electron emission portion.

  According to this, since the voltage that becomes the first power supply voltage and the voltage that becomes the second power supply voltage having different amplitudes can be generated and can be appropriately applied to the electron-emitting portion by switching the switching element, The circuit for applying the power supply voltage is simplified. As the switching element, for example, a semiconductor element such as a thyristor, a GTO (Gate Turn-Off) thyristor, a TRIAC (3-terminal bidirectional thyristor), a MOSFET, a power transistor, an analog switch, or a mechanical relay can be used. .

The power supply is
A voltage that becomes the first power supply voltage and a voltage that becomes the second power supply voltage are obtained by converting the AC voltage generated by the AC power supply connected to a single AC power supply that generates an AC voltage that changes in a sine wave shape. A transformer to produce (so-called “transformer”),
It is desirable to provide.

  According to this, by preparing only one AC power supply, the first power supply voltage and the second power supply voltage whose amplitudes are different from each other and change sinusoidally can be easily generated. It is also possible to use a commercial power source as a power source for the electron-emitting device.

In the electron emission device according to the present invention,
The power supply is
It has a primary winding and a secondary winding, and an AC voltage changing in a sine wave generated by a single AC power source is applied to the same side winding, and the reference position of the secondary winding and the same secondary winding are applied. A potential difference from the first position of the line is taken out as a voltage for generating the first power supply voltage, and a potential difference between the reference position of the secondary winding and the second position of the secondary winding is taken as the first position. A single transformer taking out as a voltage to generate two power supply voltages;
A reference connection line connecting the lower electrode side of both ends of the electron emission portion to a reference position of the secondary winding;
A first connection line connecting the upper electrode side of both ends of the electron emission portion with a first position of the secondary winding;
A rectifying element that is interposed in series with the first connection line and is forward-biased when the potential at the first position of the secondary winding is higher than the potential on the upper electrode side of both ends of the electron emission portion. When,
A second connection line connecting the upper electrode side of both ends of the electron emission portion with a second position of the secondary winding;
A switching element that is interposed in series with the second connection line and that is allowed to pass current when a switching control signal is input when it is in a state of blocking current passage;
It is preferable to comprise.

  According to this, the first power supply voltage and the second power supply are constituted by one transformer connected to a single AC power supply (for example, commercial power supply), one rectifier element, and one switching element. Voltages can be generated and these voltages can be applied to the electron emission portion at a desired timing.

Also,
The power supply is
It has a primary winding and a secondary winding, and an AC voltage changing in a sine wave generated by a single AC power source is applied to the same side winding, and the reference position of the secondary winding and the same secondary winding are applied. A potential difference from the first position of the line is taken out as a voltage for generating the first power supply voltage, and a potential difference between the reference position of the secondary winding and the second position of the secondary winding is taken as the first position. A single transformer taking out as a voltage to generate two power supply voltages;
A reference connection line connecting the upper electrode side of both ends of the electron emission portion to a reference position of the secondary winding;
A first connection line connecting the lower electrode side of both ends of the electron emission portion with a first position of the secondary winding;
A rectifying element that is interposed in series with the first connection line and is forward-biased when the potential at the first position of the secondary winding is lower than the potential at the lower electrode side of both ends of the electron emission portion. When,
A second connection line connecting the lower electrode side of both ends of the electron emission portion to a second position of the secondary winding;
A switching element that is interposed in series with the second connection line and that is allowed to pass current when a switching control signal is input when it is in a state of blocking current passage;
May be provided.

  Also by this, the first power supply voltage and the second power supply voltage are obtained by one transformer to which a single AC power supply (for example, commercial power supply) is connected, one rectifier element, and one switching element. And these voltages can be applied to the electron emission portion at a desired timing.

In such an electron emission device,
The power supply is
It is preferable that the switching control signal is configured to be generated based on an AC voltage generated by the single AC power source.

  According to this, a power source for generating the switching control signal is not required, and a circuit for generating the switching control signal can be simplified.

Furthermore, the power source is
It is preferable that the switching control signal is formed by dividing an AC voltage synchronized with an AC voltage generated by the single AC power source by a voltage dividing circuit including a resistor.

  The switching element is, for example, a thyristor. In this case, the switching control signal is a gate signal (gate voltage). The switching element may be a MOSFET, and in this case, the switching control signal is a gate voltage with respect to the source. Of course, the switching element may be another switching element described above. According to the above configuration, the switching control signal is formed by dividing the AC voltage synchronized with the AC voltage generated by the single AC power source by the voltage dividing circuit including the resistor. Therefore, the switching control signal can be generated with a very simple circuit. As a result, the cost of the power source can be reduced.

  In the electron emission device including the voltage dividing circuit, the AC voltage synchronized with the AC voltage generated by the single AC power supply is the same as the voltage appearing at the third position of the secondary winding of the single transformer. The voltage is preferably a difference voltage from the voltage appearing at the fourth position of the secondary winding.

  This eliminates the need for an extra power source, a transformer, and the like for generating the switching control signal, thereby providing a cheaper electron emission device.

Furthermore, in this case
It is preferable that at least one resistor included in the voltage dividing circuit is a variable resistor.

  According to this, the change timing of the first power supply voltage and the second power supply voltage can be controlled with a simple configuration by changing the resistance value of the variable resistor. Further, since the switching timing can be freely changed, the voltage across the element (element end voltage) when the electron emission element accumulates electrons can be changed. As a result, the electron emission amount can be controlled.

Embodiments of an electron emission device according to the present invention will be described below with reference to the drawings. The electron emission device can be applied to various devices such as an electron irradiation device, a light source, and an electronic component manufacturing device, but is applied to a display in the following description.
<First Embodiment>
(Construction)
As shown in FIGS. 1 to 3, the electron emission apparatus according to the first embodiment of the present invention includes an electron emission element 10, a protective resistor 20, a power source 30, a focusing electrode potential applying circuit 40, a collector voltage. A provisioning circuit 50.

  The electron-emitting device 10 includes a substrate 11, a plurality of lower electrodes (lower electrode layers) 12, an emitter section 13, a plurality of upper electrodes (upper electrode layers) 14, an insulating layer 15, and a plurality of focusing electrodes (focusing electrode layers) 16. I have. 1 is a partial plan view of the electron-emitting device 10, and is a cross-sectional view of the electron-emitting device 10 cut along a plane along line 1-1 in FIG. 3, and FIG. 2 is along a line 2-2 in FIG. 5 is a cross-sectional view of the electron-emitting device 10 cut along a flat plane.

  The substrate 11 has an upper surface and a lower surface parallel to a plane (XY plane) formed by the X axis and the Y axis orthogonal to each other, and the thickness direction is in the Z axis direction orthogonal to the X axis and the Y axis. It is a thin plate body. The substrate 11 is made of a material mainly composed of zirconium oxide (for example, glass or ceramics).

  Each of the lower electrodes 12 is made of a conductive material (here, silver or platinum), and is formed in a layer on the upper surface of the substrate 11. The shape of each lower electrode 12 in plan view is a strip shape having a longitudinal direction in the Y-axis direction. As shown in FIG. 1, the two lower electrodes 12 adjacent to each other are formed at positions separated by a predetermined distance in the X-axis direction. In FIG. 1, the lower electrodes 12 denoted by reference numerals 12-1, 12-2 and 12-3 are referred to as a first lower electrode, a second lower electrode and a third lower electrode, respectively, for convenience.

  The emitter section 13 is a dielectric having a high relative dielectric constant (for example, a three-component material PMN-PT-PZ of lead magnesium niobate (PMN), lead titanate (PT) and lead zirconate (PZ). , Which will be described in detail later), and is formed on the upper surface of the substrate 11 and the upper surface of the lower electrode 12. The emitter section 13 is a thin plate similar to the substrate 11. On the upper surface of the emitter section 13, as shown in an enlarged view in FIG. 4, irregularities 13 a due to dielectric grain boundaries are formed.

  Each of the upper electrodes 14 is made of a conductive material (here, platinum), and is formed in a layer shape on the upper surface of the emitter section 13. The shape of each upper electrode 14 in plan view is a rectangle having a short side and a long side along the X-axis direction and the Y-axis direction, respectively, as shown in FIG. The plurality of upper electrodes 14 are separated from each other and arranged in a matrix. Each of the upper electrodes 14 faces each of the lower electrodes 12 and is disposed at a position overlapping with each of the lower electrodes 12 in plan view.

  Further, each of the upper electrodes 14 is formed with a plurality of fine through holes 14a as shown in FIG. 4 and FIG. 5 which is a partially enlarged plan view of the upper electrode 14. In FIG. 1 and FIG. 3, the upper electrodes 14 denoted by reference numerals 14-1, 14-2 and 14-3 are respectively referred to as a first upper electrode, a second upper electrode and a third upper electrode for convenience. The plurality of upper electrodes 14 arranged in the X-axis direction are connected by a layer made of a conductor (not shown) so as to be maintained at the same potential.

  Therefore, the electron-emitting device includes an emitter portion 13 made of a dielectric, a lower electrode 12 formed under the emitter portion 13, and the emitter so as to face the lower electrode 12 across the emitter portion 13. A plurality of fine through-holes 14a are formed at the top of the portion 13, and the peripheral portion of the fine through-hole 14a facing the emitter portion 13 is separated from the emitter portion 13 by a predetermined distance. It can be said that this is an electron-emitting device having an upper electrode 14 (having an eaves structure) formed as described above.

  The lower electrode 12, the emitter portion 13, and the upper electrode 14 made of platinum resinate paste are integrated by a baking process. By this baking process for integration, the film to be the upper electrode 14 shrinks from a thickness of 10 μm to a thickness of 0.1 μm, for example. At this time, the plurality of fine through holes 14 a described above are formed in the upper electrode 14.

  As described above, the portion where the upper electrode 14 and the lower electrode 12 overlap in a plan view forms one element for electron emission. For example, the first lower electrode 12-1, the first upper electrode 14-1, and the emitter section 13 sandwiched between the first lower electrode 12-1 and the first upper electrode 14-1 constitute the first element. ing. The emitter section 13 sandwiched between the second lower electrode 12-2, the second upper electrode 14-2, the second lower electrode 12-2, and the second upper electrode 14-2 constitutes a second element. ing. Furthermore, the emitter section 13 sandwiched between the third lower electrode 12-3, the third upper electrode 14-3, the third lower electrode 12-3, and the third upper electrode 14-3 constitutes a third element. ing. As described above, the electron-emitting device 10 includes a plurality of independent electron-emitting devices.

  The insulating layer 15 is formed on the upper surface of the emitter section 13 so as to fill a space between the plurality of upper electrodes 14. The thickness (Z-axis direction length) of the insulating layer 15 is slightly larger than the thickness (Z-axis direction length) of the upper electrode 14. As shown in FIGS. 1 and 2, the X-axis and Y-axis direction ends of each insulating layer 15 are disposed on the X-axis direction both ends and the Y-axis direction both ends of the upper electrode 14.

  The focusing electrode 16 is made of a conductive material (here, silver), and is formed in a layer shape on the insulating layer 15. As shown in FIG. 3, the shape of each focusing electrode 16 in plan view is a strip shape having a longitudinal direction in the Y-axis direction. Each focusing electrode 16 is located between upper electrodes 14 adjacent to each other in the X-axis direction in plan view (between upper electrodes of elements adjacent to each other in the X-axis direction, obliquely above each upper electrode, That is, it is formed at a position slightly separated in the electron emission direction. All the focusing electrodes 16 are connected to each other by a layer made of a conductor (not shown) and are maintained at the same potential.

  In FIGS. 1 and 3, the focusing electrodes 16 denoted by reference numerals 16-1, 16-2, and 16-3 are respectively referred to as a first focusing electrode, a second focusing electrode, and a third focusing electrode for convenience. The Using this naming method, the second focusing electrode 16-2 is between the first upper electrode 14-1 of the first element and the second upper electrode 14-2 of the second element, and the first upper electrode 14-2 It can be said that it is formed obliquely above the electrode 14-1 and the second upper electrode 14-2. Similarly, the third focusing electrode 16-3 is between the second upper electrode 14-2 of the second element and the third upper electrode 14-3 of the third element, and the second upper electrode 14-2. And it can be said that it is formed obliquely above the third upper electrode 14-3.

  The electron emission device further includes a transparent plate 17, a collector electrode (collector electrode layer) 18, and a phosphor 19.

  The transparent plate 17 is made of a transparent material (here, made of glass or acrylic), and is formed at a position above the upper electrode 14 (Z-axis positive direction) by a predetermined distance. The transparent plate 17 is disposed such that the upper and lower surfaces thereof are parallel (within the XY plane) to the upper surface of the emitter section 13 and the upper surface of the upper electrode 14.

  The collector electrode 18 is made of a conductive material (here, transparent conductive film, ITO), and is formed in a layer shape on the entire lower surface of the transparent plate 17. That is, the collector electrode 18 is disposed above the upper electrode 14 so as to face the upper electrode 14.

Each of the phosphors 19 emits red, green, or blue light by electron collision. Each phosphor 19 has substantially the same shape as each upper electrode 14 in a plan view, and is disposed at a position overlapping each upper electrode 14. In FIG. 1, the phosphors 19 denoted by reference numerals 19R, 19G, and 19B emit red, green, and blue, respectively. Accordingly, in this example, the red phosphor 19R is located immediately above the first upper electrode 14-1 (Z-axis positive direction), and the green phosphor 19G is located immediately above the second upper electrode 14-2. The blue phosphor 19B is located immediately above the third upper electrode 14-3. The space surrounded by the emitter section 13, the upper electrode 14, the insulating layer 15, the focusing electrode 16 and the transparent plate 17 (collector electrode 18) is preferably substantially vacuum (10 ² to 10 ⁻⁶ Pa, more preferably 10 ^{−. 3} to 10 ⁻⁵ Pa).

  In other words, the transparent plate 17 and the collector electrode 18 constitute a space forming member that forms a sealed space together with a side wall portion of an electron emission device (not shown). The sealed space is maintained in a substantially vacuum. Therefore, the elements of the electron emission device (at least the upper part of the emitter portion 13 and the upper electrode 14 of each element) are arranged in a sealed space maintained in a substantially vacuum state by the space forming member.

  As will be described in detail later, the power supply 30 generates a drive voltage Vin that is a power supply voltage based on a commercial power supply. The power supply 30 is connected to each upper electrode 14 through the protective resistor 20 and to each lower electrode 12. Each upper electrode 14 and the protective resistor 20 are referred to as an electron emission portion EP. Therefore, the power supply 30 applies the driving voltage Vin to the electron emission portion EP (both ends of the electron emission portion EP).

  The focusing electrode potential application circuit 40 is connected to the focusing electrode 16 and always applies a constant negative potential (voltage) Vs to the focusing electrode 16.

  The collector voltage application circuit 50 is a circuit for applying a predetermined voltage (collector voltage) to the collector electrode 18, and generates a resistor (protection resistance, collector resistance) 51, a switching element 52, and a constant voltage Vc. And a switch control circuit 54. One end of the resistor 51 is connected to the collector electrode 18. The other end of the resistor 51 is connected to a fixed connection point of the switching element 52. The switching element 52 is a semiconductor element such as a MOS-FET and is connected to the switch control circuit 54.

  The switching element 52 includes two switching points in addition to the fixed connection point. The switching element 52 selectively connects one of the two switching points and the fixed connection point in response to an instruction signal from the switch control circuit 54. One of the two switching points is grounded, and the other is connected to the anode of the constant voltage source 53. The cathode of the constant voltage source 53 is grounded. The switch control circuit 54 is connected to the power supply 30 and performs switching control of the switching element 52 based on the power supply voltage.

(Principle and operation of electron emission)
Next, the operation principle regarding the electron emission of the electron emission device configured as described above will be described focusing on one element. In the following, for simplicity of explanation, the drive voltage Vin generated by the power supply 30 is a rectangular wave different from the drive voltage Vin of the first embodiment.

  First, as shown in FIG. 6, the actual potential difference Vka between the lower electrode 12 and the upper electrode 14 with respect to the potential of the lower electrode 12 (that is, the element end voltage Vka) is maintained at a predetermined positive voltage Vp. The description starts from a state immediately after all the electrons in the section 13 are emitted and no electrons are accumulated in the emitter section 13. At this time, the negative pole of the dipole of the emitter section 13 is in a state facing the upper surface of the emitter section 13 (Z-axis positive direction, that is, the upper electrode 14 side). This state is the state of the point p1 on the graph shown in FIG. The graph of FIG. 7 is a graph in which the element end voltage Vka is taken on the horizontal axis, and the charge Q in the vicinity of the upper electrode 14 is taken on the vertical axis. This graph represents the polarization-element end voltage characteristics (QV characteristics) of the electron-emitting device 10.

  In this state, the power supply decreases the drive voltage Vin toward the first voltage Vm, which is a negative predetermined voltage, as shown at time t7 in FIG. As a result, the element end voltage Vka decreases toward the point p3 via the point p2 in FIG. Then, when the element end voltage Vka becomes a voltage in the vicinity of the negative coercive electric field voltage Va shown in FIG. 7, the direction of the dipole of the emitter section 13 starts to be reversed. That is, as shown in FIG. 9, polarization reversal (negative side polarization reversal) starts. Due to this polarization inversion, the upper surface of the emitter 13, the upper electrode 14, and the contact portion (triple junction) between the surrounding medium (in this case, vacuum) and / or the fine through hole 14 a are formed. The electric field is increased at the tip portion of 14 (electric field concentration occurs), and electrons are supplied from the upper electrode 14 toward the emitter section 13 as shown in FIG. In this case, since the peripheral part of the fine through hole 14a is separated from the emitter part 13 (the upper surface of the emitter part 13) by a predetermined distance, the electric field concentration at the tip part of the fine through hole 14a is large, and the tip part The amount of electrons supplied from the emitter toward the emitter section 13 (amount of supplied electrons) can be increased. Further, in the triple junction, the angle formed by the upper electrode 14 and the upper surface of the emitter section 13 is smaller than 90 °, so that the electric field concentration becomes more conspicuous and the amount of supplied electrons increases.

  The supplied electrons are mainly in the upper part of the emitter portion 13, in the vicinity of the portion exposed from the fine through hole 14 a of the upper electrode 14, and in the vicinity of the end portion of the upper electrode 14 forming the fine through hole 14 a ( Hereinafter, it is also simply referred to as “in the vicinity of the fine through hole 14a”). Thereafter, when the predetermined time elapses and the negative side polarization reversal is completed at time t9 in FIG. 8, the element end voltage Vka rapidly changes toward the negative predetermined voltage (first voltage) Vm, and at time t10. Negative predetermined voltage Vm. As a result, the accumulation of electrons is completed (the electron accumulation saturation state is reached). This state is the state at point p4 in FIG.

  Next, the power supply changes the drive voltage Vin to the second voltage Vp, which is a positive predetermined voltage, at time t11 shown in FIG. Thereby, the element end voltage Vka begins to increase. At this time, until the element end voltage Vka reaches the voltage Vb (point p6) slightly smaller than the positive coercive electric field voltage Vd corresponding to the point p5 in FIG. 7, as shown in FIG. The charged state is maintained. Thereafter, the element end voltage Vka reaches a voltage in the vicinity of the positive coercive electric field voltage Vd at time t13 shown in FIG. As a result, the negative pole of the dipole starts to face the upper surface side of the emitter section 13. That is, as shown in FIG. 12, the polarization is reversed again (positive-side polarization reversal starts). This state is a state near the point p5 in FIG.

  Thereafter, at a time near the time when the positive-side polarization reversal is completed at time t14 in FIG. 8, the number of dipoles in which the negative electrode is reversed to the upper surface side of the emitter section 13 increases. As a result, as shown in FIG. 13, the electrons accumulated in the vicinity of the fine through hole 14a are started to be released upward (Z-axis positive direction) through the fine through hole 14a due to the repulsive force of Coulomb.

  When the positive-side polarization inversion is completed at time t14 in FIG. 8, the element end voltage Vka starts to increase rapidly, and electrons are actively emitted. Next, at time t16, the electron emission is completed, and the element end voltage Vka reaches the second voltage Vp. As a result, the state of the emitter section 13 returns to the initial state shown in FIG. 6 (the state at the point p1 in FIG. 7). The above is a series of operating principles relating to accumulation (extinguishing) and emission (lighting / light emission) of electrons.

  By the way, when electrons are emitted through the fine through holes 14a of the upper electrode 14, as shown in FIG. 14, the electrons gradually spread (cone shape) and travel in the positive direction of the Z axis. As a result, in the conventional apparatus, the electrons emitted from one upper electrode 14 (for example, the second upper electrode 14-2) are phosphors (for example, the green phosphor 19G) that exist immediately above the upper electrode 14. ) As well as adjacent phosphors (red phosphor 19R and blue phosphor 19B). When such a state occurs, the color purity decreases and the sharpness of the image decreases.

  On the other hand, the electron-emitting device 10 according to this embodiment includes a focusing electrode 16 to which a negative potential is applied. The focusing electrode 16 is disposed between the adjacent upper electrodes 14 (between the upper electrodes of the adjacent elements) and slightly above the upper electrode 14. Therefore, as shown in FIG. 15, the electrons emitted from the fine through holes 14 a of the upper electrode 14 are emitted in a substantially upward direction without spreading due to the electric field provided by the focusing electrode 16.

  As a result, the electrons emitted from the first upper electrode 14-1 reach only the red phosphor 19R, the electrons emitted from the second upper electrode 14-2 reach only the green phosphor 19G, and the third upper electrode Electrons emitted from the electrode 14-3 reach only the blue phosphor 19B. Therefore, a clearer image can be obtained without lowering the color purity of the display.

(Unnecessary electron emission and estimation reason)
In the electron emission device that operates as described above, as will be understood from the collector current shown in FIG. 8 (the amount of electrons that reach the collector electrode per unit time), the electron emission starts near time t14. The amount of electron emission per unit time becomes maximum at time t15, and electron emission is completed at time t16. That is, regular light emission is performed during this period. However, as a result of experiments conducted by the inventor, it has been found that unintended light emission (unnecessary electron emission) occurs as described below.

(1) Normal light emission First, changes in the drive voltage Vin, device end voltage Vka, device current Ik, and optical output APD when normal electron emission (light emission) is performed when the drive voltage Vin is changed to a rectangular wave shape. Will be described again with reference to FIG. The element current Ik is a current that flows through the emitter section 13 between the lower electrode 12 and the upper electrode 14. The light output APD is a value obtained by converting emitted light into a current by an avalanche photodiode, and is represented by a negative value in the figure.

  As shown in FIG. 16, when the drive voltage Vin rises steeply at time t1 and changes from the first negative voltage Vm, which is a negative predetermined voltage, to the second positive voltage Vp, which is a positive predetermined voltage, the emitter A large inrush current flows through the portion 13. Therefore, the device current Ik reaches a peak immediately after the time t1, and then reaches 0 relatively quickly. On the other hand, since the positive side polarization reversal occurs at time t2 to time t3 immediately after time t1, the element end voltage Vka increases rapidly from time t1 to time t2 and then gradually increases until time t3. The element end voltage Vka increases in the period up to time t4 when positive side polarization reversal ends at time t3 (exceeds the positive coercive electric field voltage), and after time t4, the second voltage Vp of the drive voltage Vin. The voltage is consistent with In this case, as can be understood from the light output APD, the emission (light emission) of electrons starts near time t3, reaches a maximum just before time t4, and then stops.

  Next, when the drive voltage Vin sharply falls at time t5 and changes from the second voltage Vp, which is a positive predetermined voltage, to the first voltage Vm, which is a negative predetermined voltage, a large negative voltage is generated in the emitter section 13. Inrush current flows. Therefore, the device current Ik reaches a peak immediately after time t5. On the other hand, since negative polarization reversal occurs from time t6 to time t7 immediately after time t5, the element end voltage Vka decreases relatively rapidly from time t5 to time t6 and then becomes substantially constant from time t7. When the negative side polarization reversal ends at time t7 (exceeds the negative coercive electric field voltage), the element end voltage Vka rapidly decreases in the period up to time t8, and after the time t8, the first end of the drive voltage Vin. The voltage coincides with the voltage Vm. Further, the element current Ik suddenly approaches 0 from time t5 to time t6, and then becomes a substantially constant value until time t7, and suddenly approaches 0 again from time t7 to time t8. As understood from FIG. 16, no electrons are emitted between time t5 and time t8.

(2) Abnormal light emission (electron emission at unnecessary time and excessive electron emission)
Next, it will be described at what point in time unnecessary electron emission (including the case where the amount of electron emission becomes excessive) occurs when the drive voltage Vin is changed to a rectangular wave shape.

Such unnecessary electron emission mainly occurs at the following four points.
(A) A second voltage that is a positive predetermined voltage from a first voltage Vm that is a negative predetermined voltage (or a third voltage Vn that is equal to an intermediate voltage applied during non-selection of an element to be described later) as a drive voltage Vin. Unnecessary electron emission occurs immediately after the time of change to Vp (that is, the time when the drive voltage Vin is raised to start electron emission, time t1, t11 in FIG. 8 and time t1 in FIG. 16). (See region A1 in FIG. 17). This is because a large inrush current flows between the upper electrode 14 and the lower electrode 12 (that is, the emitter section 13) as the drive voltage Vin changes suddenly (the element current Ik becomes excessive). It is estimated that

(B) When the drive voltage Vin is changed to the second voltage Vp which is a positive predetermined voltage, the positive-side polarization inversion occurs and the positive-side polarization inversion is completed (time t14 in FIG. 8 and FIG. 16). Immediately after time t3), unnecessary electron emission occurs (see region A2 in FIG. 17 and FIG. 18). This is because the element end voltage Vka changes abruptly immediately after the positive side polarization reversal of the emitter section 13 is completed (when the positive coercive electric field voltage is exceeded) (time change rate (dVka of the element end voltage Vka)). / Dt) is excessively large).

(C) When the drive voltage Vin is changed from the second voltage Vp, which is a positive predetermined voltage, to the first voltage Vm, which is a negative predetermined voltage (that is, when the drive voltage Vin is lowered to start electron emission). Yes, unnecessary electron emission occurs immediately after time t7, t17 in FIG. 8 and time t5 in FIG. 16 (see region A3 in FIG. 17). This is presumed to be caused by a large inrush current (the element current Ik becomes excessive) as the drive voltage Vin suddenly changes.

(D) When the drive voltage Vin is changed to the first voltage Vm which is a negative predetermined voltage, the negative side polarization reversal occurs and the negative side polarization reversal is completed (at times t9, t19 and FIG. 8). Immediately after time t7) in FIG. 16, unnecessary electron emission occurs (see region A4 in FIG. 17 and FIG. 19). This is because the element end voltage Vka changes abruptly after the negative polarization inversion of the emitter section 13 is completed (the time change rate (dVka / dt) of the element end voltage Vka becomes excessive). It is estimated that

  Based on the above knowledge, the inventor repeated experiments and obtained a conclusion that abnormal electrons can be emitted when the drive voltage Vin is gradually increased instead of being changed into a rectangular wave when electrons are emitted. It was. That is, when the drive voltage Vin is increased to emit electrons, the peak (maximum value) of the device current Ik decreases as the voltage change rate of the drive voltage Vin decreases, and in particular, the change in the device end voltage Vka is driven. It was confirmed that when the voltage change rate of the drive voltage Vin is set so as to follow the change of the voltage Vin, the peak of the device current Ik is effectively reduced, and abnormal electron emission can be avoided.

  Furthermore, the inventor has concluded that abnormal electrons can be emitted if the drive voltage Vin is gradually decreased when electrons are accumulated in the emitter section 13. That is, even when the drive voltage Vin is decreased in order to accumulate electrons, the peak (maximum value) of the device current Ik decreases as the voltage change rate of the drive voltage Vin decreases, and abnormal electron emission occurs. It was confirmed that it can be avoided.

(Configuration and operation of power supply)
The power supply 30 according to the first embodiment is configured based on the above-described knowledge, and as illustrated in the conceptual diagram of FIG. 20, the first power supply voltage Vin1 that changes in a sine wave shape and the sine wave shape change. A second power supply voltage Vin2 is formed, and a power supply voltage (drive voltage) Vin formed by appropriately switching these voltages with a switching element is applied to the electron emission portion EP.

  That is, the power supply 30 generates the first power supply voltage Vin1 and the second power supply voltage Vin2 that are synchronized with each other by transforming (voltage converting) the commercial power supply CV (AC100V) by the transformer 31. Then, the power supply 30 switches and controls the switching element SW so as to apply the first power supply voltage Vin1 or the second power supply voltage Vin2 to the electron emitting portion EP including the electron emitting element 10 and the protective resistor 20.

  More specifically, as shown in FIG. 21, the power source 30 includes a transformer (single transformer) 31, a diode (first rectifier element) 32 that is one of the switching elements SW, a first resistor. 33, a thyristor (second rectifier element) 34, which is one of the switching elements SW, a second resistor 35, a third resistor (fixed or variable resistor) 36, and a fourth resistor 37.

  The transformer 31 includes a primary winding 31a and a secondary winding 31b. Terminals at both ends of the primary winding 31a are referred to as a terminal T1 and a terminal T2, respectively. The secondary winding 31b is provided with a plurality of terminals T3 to T8 arranged in order on the secondary winding 31b with a predetermined interval. The terminal T3 is a terminal at the lower end of the secondary winding 31b. The terminal T8 is a terminal at the upper end of the secondary winding 31b.

  The transformer 31 converts a voltage obtained by transforming an AC voltage applied to the terminals T1 and T2 at both ends of the primary winding 31a with a predetermined transformation ratio (here, 2.1 times) by the electromagnetic induction effect into the secondary winding 31b. Between both terminals T8 to T3. Terminals T1 and T2 at both ends of the primary winding 31a are connected to a commercial power source that is an AC power source (for example, a power source of AC 100 (V), 60 Hz, or 50 Hz in Japan). The terminals T1 and T2 are connected to commercial power sources AC100V (−) and AC100V (+), respectively.

  Accordingly, an AC voltage of 210 (V) (amplitude = about 297 V) that changes in a sine wave shape with the terminal T3 as the reference voltage 0 (V) is generated at the terminal T8 of the secondary winding 31b. The 210 (V) AC voltage generated at the terminal T8 is simply referred to as “AC210 (V)”. The same naming method is applied to voltages appearing at other terminals.

  As a result, AC voltages of 28, 39, 50, and 175 V are generated at terminals T4, T5, T6, and T7 of the secondary winding 31b using the terminal T3 as a reference voltage, respectively. For convenience of explanation, the position of the terminal T8 is referred to as a first position of the secondary winding 31b, and the position of the terminal T6 is referred to as a second position and a third position of the secondary winding 31b. The position of T5 is referred to as the fourth position of the secondary winding 31b.

  The terminal T8 is connected to the anode A of the diode 32 by the connection line L1. The cathode K of the diode 32 is connected to the point P1 via a first resistor 33 inserted in series with the connection line L1. The point P <b> 1 is connected to the upper electrode 14 of the electron emitter 10 through the protective resistor 20. As described above, the electron emitter 10 and the protective resistor 20 constitute an electron emitter EP. Therefore, it can be said that the point P1 is connected to the upper electrode 14 side of the electron emission portion EP.

  The terminal T6 is connected to the cathode K of the thyristor 34 by a connection line L2. The anode A of the thyristor 34 is connected to the point P1 through a second resistor 35 inserted in series with the connection line L2.

  The terminal T5 is connected to the gate G of the thyristor 34 via the fourth resistor 37. A point P2 between the cathode K of the thyristor 34 and the terminal T6 is connected via a third resistor 36 to a point P3 between the fourth resistor 37 and the gate G of the thyristor 34. Therefore, the potential at the point P3 is a potential obtained by dividing the potential at the terminal T6 and the potential at the terminal T5 by the voltage dividing circuit BC including the third resistor 36 and the fourth resistor 37.

  Thereby, the gate G of the thyristor 34 has an AC voltage appearing at the terminal T6 (third position of the secondary winding 31b) and an AC voltage appearing at the terminal T5 (fourth position of the secondary winding 31b). A voltage proportional to the difference voltage is applied. The thyristor 34 opens the gate when the potential of the gate G becomes larger than the potential of the cathode K by a predetermined threshold voltage (for example, 0.6 (V)) (hereinafter also referred to as “the thyristor gate is turned on”). In this state, the anode A and the cathode K conduct when forward biased (pass the forward current).

  The position of the terminal T3 is also referred to as a reference position of the secondary winding 31b for convenience. The terminal T3 is connected to the lower electrode 12 of the electron-emitting device 10 (the lower electrode 12 side of the electron-emitting portion EP) by a connection line L3 that is a reference connection line.

  Next, the operation of the power supply 30 configured as described above will be described with reference to FIGS. In the following, the power supply voltage (drive voltage Vin) is the potential at the point P1 when the reference connection line L3 (the potential at the terminal T3) is the reference potential (power supply voltage = the potential at the point P1−the potential at the terminal T3). It is defined as In FIG. 22A, a solid curve CL1 is a power supply voltage, a broken curve CL2 is an element end voltage, a dashed-dotted curve CL3 is a large AC voltage AC210 (V) appearing at a terminal T8, and a two-dot chain line. Curve CL4 in FIG. 4 shows the small-side AC voltage AC50 (V) appearing at the terminal T6. Further, a curve CL5 in FIG. 22B shows the emission electron current. The emitted electron current is a current that flows through the collector electrode 18 due to electron emission from the electron-emitting device 10. That is, the emission electron current indicates the amount of electrons emitted per unit time (electron emission amount).

  First, it is assumed that electrons are accumulated near the upper portion of the emitter section 13 at time t1. Further, it is assumed that AC210 (V) and AC50 (V) appearing at the terminals T8 and T6 at time t1 are both 0 (V). Accordingly, AC 210 (V) and AC 50 (V) gradually increase from 0 (V) in a sinusoidal manner after time t1.

  At this time, the element end voltage Vka is a negative voltage near 0 (V). Therefore, immediately after time t1, the potential of the terminal T8 is higher than the potential of the upper electrode 14 of the electron-emitting device 10, so that the diode 32 is biased in the forward direction. As a result, the diode 32 allows the forward current I1 to pass. As a result, the potential of the terminal T8 (the voltage of AC210 (V) that is an AC voltage appearing at the terminal T8) is applied to the point P1. That is, AC210 (V) is applied to the upper electrode 14 side of the electron emission portion EP (AC210 (V) is applied to the electron emission portion EP).

  As a result, a current flows from the terminal T8 to the electron emission portion EP via the first connection line L1, and further flows from the electron emission portion EP to the terminal T3. As a result, the element end voltage Vka gradually increases so as to follow AC210 (V). Therefore, the positive polarization inversion described above occurs, and electrons are emitted through the fine through hole 14 a of the upper electrode 14.

  Thereafter, at time t2, the magnitude of the current flowing through the protective resistor 20 and the electron-emitting device 10 becomes extremely small. As a result, after the time t2, the element end voltage Vka changes so as to substantially coincide with AC210 (V).

  When time elapses further from time t2 and becomes time t3, AC210 (V) becomes a positive peak (a maximum value having the same magnitude as the amplitude). Therefore, after time t3, the potential at the point P1 (the potential on the upper electrode 14 side of the electron emission portion EP) becomes higher than the potential at the terminal T8, so that the diode 32 is biased in the reverse direction. For this reason, the diode 32 becomes a non-conduction (cutoff) state. As a result, the power supply voltage Vin does not change with the AC 210 (V) and is substantially maintained at the value at that time, or gradually decreases due to the leakage current.

  On the other hand, as indicated by the curve CL5 in FIG. 22B, the emission electron current becomes maximum at time tmax before time t3. In other words, the power source 30 has a unit per unit time during which at least the electrons accumulated in the emitter section 13 are emitted through the fine through-holes 14a from when the electron-emitting device 10 has accumulated electrons in the emitter section 13 (time t1). The first power supply voltage whose absolute value changes in a sine wave shape so that the potential of the upper electrode 14 becomes higher than the potential of the lower electrode 12 during a period up to the time point (time tmax) when the electron emission amount which is the amount of A power supply voltage Vin is generated, and the first power supply voltage is applied to the electron emission portion EP. It should be noted that substantially all of the electrons accumulated in the vicinity of the upper portion of the emitter section 13 are released by the time t4 slightly past the time t3.

  Further, the potential of the terminal T6 when referred to the terminal T5 (hereinafter referred to as “voltage V65 between the terminals T6 and T5”) changes as indicated by a curve CL7 in FIG. Further, the voltage between the point P2 and the point P3 obtained by dividing the voltage V65 by the third resistor R3 and the fourth resistor R4 (the potential at the point P2 with respect to the point P3) is represented by a curve CL8 in FIG. It changes as shown. These voltages are synchronized with AC210 (V) and AC50 (V). The potential difference between the point P2 and the point P3 is a voltage between the cathode K and the gate G of the thyristor 34.

  Further, as described above, in the thyristor 34, the potential of the gate G is set to the threshold voltage (for example, 0. 0) with respect to the potential of the cathode K in a state where the anode A and the cathode K are biased in the forward direction. 6 (V)) or more, the gate is opened to conduct. That is, the thyristor 34 can pass a forward current when the voltage between the points P2 and P3 becomes a negative voltage having an absolute value larger than a predetermined absolute value (absolute value of the threshold voltage). Become.

  Therefore, time t6 passes after time t5 when the voltage (AC210 (V), AC50 (V), etc.) generated by transforming the voltage generated by the commercial power supply changes from a positive voltage to a negative voltage. When the voltage between the points P2 and P3 reaches a negative threshold voltage, a signal for turning on the thyristor gate (hereinafter referred to as “thyristor gate on signal”) is generated.

  When the thyristor gate-on signal is generated at time t6, the potential of the terminal T6 at which AC50 (V) appears is a negative potential. On the other hand, the potential on the upper electrode 14 side of the electron emission portion EP is a positive potential. Accordingly, since the thyristor 34 is biased in the forward direction, the forward current I2 is allowed to pass therethrough. Thereby, the potential of the terminal T6 (the voltage of AC50 (V) that is an AC voltage appearing at the terminal T6) is applied to the point P1 on the upper electrode 14 side of the electron emission portion EP. In other words, since AC50 (V) is applied to the electron emission portion EP after time t6, the power supply voltage changes in a sinusoidal shape along AC50 (V).

  Accordingly, a current flows from the electron emission portion EP toward the terminal T6 through the second connection line L2. Furthermore, a current flows from the terminal T3 toward the electron emission portion EP. As a result, the element end voltage Vka rapidly decreases to near 0 (V) immediately after time t6.

  Between time t6 and time t7, AC50 (V) decreases in a sine wave shape. In other words, a negative voltage whose absolute value is gradually increased is applied to the upper electrode 14 side of the electron emission portion EP. As a result, since the negative side polarization reversal described above occurs immediately after time t6 and between time t7, the element end voltage Vka becomes a voltage in the vicinity of a negative coercive electric field voltage different from AC50 (V). When the negative polarization inversion is completed at time t7, the potential on the upper electrode 14 side of the electron emission portion EP changes with AC50 (V). Note that the accumulation of electrons in the emitter section 13 is substantially completed immediately after time t7 or time t7. Accordingly, the power source 30 has a lower potential of the lower electrode 12 than that of the upper electrode 14 during a period from when the electrons are not accumulated in the emitter section 13 until at least the electrons are accumulated in the emitter section 13. Thus, the second power supply voltage whose absolute value increases in a sine wave form is generated as the power supply voltage Vin, and the power supply voltage Vin is applied to the electron emission portion EP.

  When a further time elapses from time t7 and becomes time t8, AC50 (V) becomes a negative peak and starts increasing after time t8. As a result, the potential at the terminal T6 becomes higher than the potential at the point P1 (the potential on the upper electrode 14 side of the electron emission portion EP). Accordingly, since the thyristor 34 is biased in the reverse direction, no current passes through the thyristor 34 after time t8. As a result, the power supply voltage Vin does not change with AC50 (V) and is substantially maintained at the value at the time t8.

  At time t9, as shown in FIG. 23, the voltage between the points P2 and P3 becomes a negative voltage having an absolute value smaller than a predetermined absolute value (absolute value of the threshold voltage). Therefore, a thyristor gate-off signal is generated at time t9. At time t10, the diode 32 is biased again in the forward direction, and then the same operation as after time t1 is resumed. The above is the operation of the electron emission device according to the present embodiment.

  The thyristor 34 starts to pass forward current when a thyristor gate-on signal is input while being biased in the forward direction. In this state, even if a thyristor gate-off signal is input, the thyristor continues to pass forward current (not blocked). The thyristor is shut off when a reverse bias is applied or when the current passing through the thyristor becomes equal to or lower than the holding current, and shuts off all current until the thyristor gate-on signal is input again. It becomes like this.

  As described above, the power supply 30 of the electron emission device according to the first embodiment generates the power supply voltage Vin to be applied to the electron emission section EP in which the electron emission element 10 and the protective resistor 20 are connected in series. Furthermore, the power source 30 is configured to provide electrons per unit time when the electron-emitting device 10 is in a state where electrons are accumulated in the emitter section 13 and at least electrons accumulated in the emitter section 13 are emitted through the fine through holes 14a. The first power supply voltage Vin1 whose absolute value changes sinusoidally so that the potential of the upper electrode 14 becomes higher than the potential of the lower electrode 12 during a period until the discharge amount becomes maximum (for example, time t1 to tmax). AC210 (V) is generated as the power supply voltage Vin. In addition, the power source 30 has a period from when the electron-emitting device 10 is not accumulating electrons in the emitter section 13 to at least accumulating electrons in the emitter section 13 (for example, times t6 to t8), AC50 (V), which is the second power supply voltage Vin2, whose absolute value increases sinusoidally so that the potential of the electrode 12 becomes higher than the potential of the upper electrode 14, is generated as the power supply voltage Vin.

  Accordingly, the absolute value of the power supply voltage Vin applied to the electron emission portion EP gradually increases in a sine wave form at both the start of accumulation of electrons in the emitter portion 13 and the start of emission of electrons from the emitter portion 13. Therefore, the absolute value of the element end voltage Vka also gradually increases so as to follow the power supply voltage. As a result, since the difference between the power supply voltage Vin and the element end voltage Vka does not increase, the generation of Joule heat is small, and the amount of power that is wasted can be reduced.

  In addition, since no large Joule heat is generated, the temperature of the electron-emitting device 10 does not increase. Therefore, it is possible to avoid the characteristics of the emitter section 13 from being changed by heat. Furthermore, since it is possible to avoid gasifying the substance adsorbed on the electron-emitting device 10, generation of plasma due to the gasified substance can be suppressed. As a result, it is possible to avoid excessive emission of electrons and damage to the electron-emitting device 10 due to ion bombardment.

  In addition, after the first power supply voltage AC210 (V) for emitting electrons starts to be applied, the absolute value of the first power supply voltage AC210 (V) gradually increases. Thereby, the magnitude of the inrush current flowing through the emitter section 13 can be reduced, and the change rate of the element end voltage after completion of the positive side polarization reversal of the emitter section by the application of the first power supply voltage can be reduced. As a result, unnecessary light emission due to unnecessary emission of electrons due to inrush current and unnecessary light emission due to unnecessary emission of electrons due to a sudden change in device voltage immediately after completion of positive side polarization reversal can be avoided.

  Furthermore, after applying the second power supply voltage AC50 (V) for accumulating electrons and after completing the negative polarization inversion of the emitter section 13, the absolute value of the second power supply voltage AC50 (V) gradually increases. To increase. Therefore, it is possible to prevent electron emission and unnecessary light emission associated therewith at an unnecessary timing presumed to be caused by a sudden change in the device end voltage after the negative side polarization reversal of the emitter portion is completed.

  The amplitude of the first power supply voltage AC210 (V) is larger than the amplitude of the second power supply voltage AC50 (V). Thereby, the power supply voltage according to the QV characteristic of the electron-emitting device 10 as shown in FIG. 7 can be provided. Accordingly, either the first power supply voltage or the second power supply voltage becomes unnecessarily large as in the case where the amplitudes of the first power supply voltage and the second power supply voltage are made equal, or power is wasted. Therefore, it is possible to avoid such a problem that the voltage of the voltage becomes smaller than necessary and a desired amount of electrons cannot be emitted.

  In addition, the power supply 30 is a switching element SW (switching the application state of the first power supply voltage (voltage AC210V serving as the first power supply voltage) and the second power supply voltage (voltage AC50V serving as the second power supply voltage) to the electron emission unit EP. A thyristor 34) is provided. Thereby, the structure of the power supply 30 is simplified.

  Furthermore, the power source 30 uses a single AC power source (commercial power source) that generates an AC voltage that changes sinusoidally, and a voltage that becomes the first power source voltage by converting the AC voltage generated by the AC power source. A transformer 31 is provided that generates AC 210 (V) and a voltage AC 50 (V) as the second power supply voltage.

  Therefore, by preparing only one AC power supply, the first power supply voltage and the second power supply voltage whose amplitudes are different from each other and change sinusoidally can be easily generated. It is also possible to use a commercial power source as a power source for the electron-emitting device.

More specifically, the power supply 30 has the following characteristics.
(1) The power source 30 uses a commercial power source that is a single AC power source that generates an AC voltage that changes in a sinusoidal shape.
(2) The power supply 30 has a primary winding 31a and a secondary winding 31b, and applies an alternating voltage generated in a sine wave generated by the single alternating-current power supply to the same-side winding 31a. The potential difference between the reference position (terminal T3) of the secondary winding and the first position (terminal T8) of the secondary winding 31b is taken out as a voltage AC210 (V) for generating the first power supply voltage. A potential difference between the reference position (terminal T3) of the secondary winding 31b and the second position (terminal T6) of the secondary winding 31b is taken out as a voltage AC50 (V) for generating the second power supply voltage. One transformer 31 is provided.

(3) The power source 30 includes a reference connection line L3 that connects the lower electrode 12 side of both ends of the electron emission portion EP to the reference position (terminal T3) of the secondary winding 31b, and both ends of the electron emission portion EP. A first connection line L1 that connects the upper electrode 14 side to the first position (terminal T8) of the secondary winding 31b, and a first connection line L1 that is interposed in series with the first connection line L1. A first rectifying element 32 biased in the forward direction when the potential of the position (terminal T8) is higher than the potential of the upper electrode 14 (potential on the upper electrode 14 side of the electron emission portion EP).

(4) The power supply 30 includes a second connection line L2 and a second connection line L2 that connect the upper electrode 14 side of both ends of the electron emission portion EP to the second position (terminal T6) of the secondary winding 31b. And a thyristor 34 that is a switching element that is in a state of allowing the passage of current when a switching control signal is input when the passage of the current is interrupted. The thyristor 34 is forward-biased when the potential of the second position (terminal T6) of the secondary winding 31b is lower than the potential of the upper electrode 14 (potential on the upper electrode 14 side of the electron emission portion EP).

  Due to these characteristics, the power supply 30 includes a single AC power supply (for example, a commercial power supply), a single transformer 31, a single rectifying element 32, and a single switching element 34. The AC 210 (V) and the second power supply voltage AC 50 (V) can be generated, and these voltages can be selectively applied to the electron emission unit EP by the switching element 34 at a desired timing.

  The switching control signal (the voltage applied between the gate G and the cathode K of the thyristor 34) is generated based on the AC voltage AC100 (V) generated by a single AC power supply (commercial power supply). Therefore, a power source for generating the switching control signal is not necessary.

  Further, the power source 30 is configured to divide the switching control signal into an AC voltage (AC voltage transformed by the transformer 31) synchronized with the AC voltage generated by the single AC power source, and includes a resistor 36 and a resistor 37. It is formed by dividing the pressure by. Therefore, the switching control signal can be generated with a very simple circuit. As a result, the cost of the power supply 30 can be reduced.

  Furthermore, the power supply 30 is connected to the voltage AC50 (V) appearing at the third position (terminal T6) of the secondary winding 31b of the single transformer 31 and the fourth position (terminal T5) of the secondary winding 31b. The voltage difference from the appearing voltage AC39 (V) is obtained as an AC voltage synchronized with the AC voltage generated by the single AC power supply. For this reason, an extra power supply, a transformer, etc. become unnecessary, and a cheaper electron emission apparatus can be provided.

  Note that at least one of the resistors 36 and 37 included in the voltage dividing circuit BC is preferably a variable resistor whose resistance value can be changed by an external signal or operation. According to this, the change timing of the first power supply voltage and the second power supply voltage can be controlled with a simple configuration by changing the resistance value of the variable resistor. Further, since the switching timing can be freely changed, the time during which the second voltage AC50 (V) is applied to the electron emission portion EP can be changed. As a result, the voltage between both ends of the element (element end voltage) during the electron accumulation of the electron-emitting device 10 can be changed, so that the amount of electrons accumulated in the upper portion of the emitter section 13 can be changed. Can be controlled. Such a voltage dividing circuit may be configured using an inductor or a capacitor. The voltage dividing circuit BC using only a resistor as described above is preferable in that a stable voltage can be generated.

(Control of collector electrode)
The collector voltage applying circuit 50 has a collector voltage at a predetermined time within a period from “the time when the electron emission through the fine through hole 14a is substantially completed” to “the time when the gate of the thyristor 34 is turned on”. A second collector voltage V2 is applied to the collector electrode 18 so that the voltage changes from the first predetermined voltage to a second predetermined voltage smaller than the first predetermined voltage. That is, the collector voltage application circuit 50 switches the connection destination of the fixed connection point of the switching element 52 from the switching point connected to the constant voltage source 53 to the switching point grounded at this predetermined time.

  The switching element 52 may be configured to be a floating point that does not connect the grounded switching point anywhere. In this case, the switching element 52 switches the connection point of the fixed connection point from the switching point connected to the constant voltage source 53 to the switching point that is the floating point, whereby the collector electrode 18 is changed to the floating state. It is done. Thus, applying the second collector voltage V2 to the collector electrode 18 by grounding the collector electrode 18 or putting the collector electrode 18 in a floating state is also referred to as “turning off the collector electrode”.

  When the collector electrode 18 is turned off, the collector electrode 18 does not form an electric field that attracts the emitted electrons or reduces the strength of such an electric field. As a result, unnecessary electron emission (unnecessary light emission) is avoided.

  Thereafter, the collector voltage application circuit 50 is set at a predetermined time within a period from “the time when the electron accumulation is substantially completed in the upper portion of the emitter 13” to “before the time when the electron emission is completed again”. Thus, the connection point of the fixed connection point of the switching element 52 is switched from the grounded switching point to the switching point connected to the constant voltage source 53. That is, the collector voltage application circuit 50 resumes the application of the first collector voltage V1 (= Vc) to the collector electrode 18 at this predetermined time (for convenience, referred to as “collector electrode on time”).

  Thus, the emitted electrons travel above the upper electrode 14 while being accelerated (given high energy) by the electric field formed by the collector electrode 18. Accordingly, since the phosphor 19 is irradiated with electrons having high energy, a large luminance can be obtained. In other words, the collector electrode 18 to which the first collector voltage V <b> 1 is applied attracts the emitted electrons, and as a result, a necessary amount of electrons reach the vicinity of the collector electrode 18.

  By controlling the collector electrode 18 in this way, the collector voltage becomes the second predetermined voltage (in this example, 0 V which is the ground potential) at least from the voltage decrease start time to the electron accumulation completion time, or The collector electrode is maintained in a floating state.

  Therefore, unnecessary emission of electrons that can be attributed to a large inrush current flowing through the emitter section 13 during electron accumulation can be avoided more reliably. Furthermore, unnecessary emission of electrons considered to be caused by “a large voltage change rate of the element end voltage Vka” that occurs after the completion of the negative-side polarization inversion can be avoided more reliably.

Note that the collector electrode on time can also be set as described below.
(A) The time when the collector electrode is turned on is defined as “the time when forward current starts to flow through the diode 32”.

  Thereby, unnecessary electron emission in the electron accumulation period can be avoided. Furthermore, since the first collector voltage is applied to the collector electrode 18 over the entire period during which electrons are being emitted, normally emitted electrons can be guided to the vicinity of the collector electrode 18.

(B) The collector electrode on time is set to a predetermined time within a period from “a time point immediately after the point when the inrush current accompanying the positive side polarization reversal reaches a peak” to “a positive side polarization reversal completion point”.

  Thereby, unnecessary electron emission during the electron accumulation period and unnecessary electron emission due to a large inrush current at the time of positive side polarization inversion can be avoided. Further, the first collector voltage is applied to the collector electrode after the positive side polarization reversal is completed. Accordingly, electrons that are normally emitted after completion of positive side polarization reversal can be guided to the collector electrode side.

(C) The collector electrode ON time is set to a predetermined time within a period from “positive side polarization reversal completion time” to “electron emission substantially complete time”.

  Thereby, unnecessary electron emission in the electron accumulation period can be avoided. Furthermore, unnecessary electron emission due to an inrush current or the like until the positive side polarization reversal is completed can be avoided. In addition, the first collector voltage is applied to the collector electrode at a time before the completion of electron emission. Therefore, normally emitted electrons can be guided to the collector electrode side. In addition, since the first collector voltage is applied to the collector electrode only during a substantially scheduled electron emission period, excessive electron emission can be appropriately suppressed.

(D) The period from the time when the collector electrode is turned on to the time when the amount of electrons per unit time reaching the collector electrode from the emitter (the current flowing through the collector electrode) becomes maximum from the time when the positive side polarization reversal is completed Set to a predetermined time.

  Thereby, unnecessary electron emission in the electron accumulation period can be avoided. Furthermore, unnecessary electron emission due to an inrush current or the like until the positive side polarization reversal is completed can be avoided. In addition, the first collector voltage is applied to the collector electrode after the point when the current flowing through the collector electrode becomes maximum. As a result, only normally emitted electrons can be more reliably guided to the collector electrode side. In other words, it is possible to ensure the required amount of electron emission while avoiding excessive emission of electrons.

(E) The collector electrode on time is set to “the time when the actual element end voltage Vka reaches the predetermined threshold voltage Vth”. In this case, it is preferable that the predetermined threshold voltage Vth is selected so that the collector electrode ON time is a predetermined time within a period from the time when the positive side polarization reversal is completed to the time when the current flowing through the collector becomes maximum.

  Thereby, unnecessary electron emission in the electron accumulation period can be avoided. Furthermore, unnecessary electron emission due to an inrush current or the like when the drive voltage Vin starts to increase can be avoided. Further, since the method of changing the device end voltage Vka changes according to the image (the amount of electrons to be emitted), if the time when the device voltage reaches the predetermined threshold voltage Vth is the collector electrode on time, the device end voltage Regardless of how Vka changes, the collector electrode can always be turned on at an appropriate timing (a timing at which as many electrons as are normally emitted are guided to the collector electrode while suppressing unnecessary electron emission).

<Second Embodiment>
Next, an electron emission device according to a second embodiment of the present invention will be described with reference to FIGS. This electron emission device is different from the electron emission device of the first embodiment only in that the power source 30 of the electron emission device according to the first embodiment is replaced with a power source 70. Accordingly, the following description will focus on such differences.

  Similarly to the power supply 30, the power supply 70 is composed of a MOSFET by generating a first power supply voltage Vin <b> 1 and a second power supply voltage Vin <b> 2 that are synchronized with each other by transforming (voltage converting) a commercial power supply CV (AC100V) with a transformer 71. The switching element SW is switched and applied, and the first power supply voltage Vin1 or the second power supply voltage Vin2 is applied to the electron emission portion EP including the electron emission element 10 and the protective resistor 20.

  However, in the power source 70, the upper electrode 14 of the electron-emitting device 10 (on the side of the upper electrode 14 of the electron-emitting portion EP) is a terminal T3 that is the reference position of the secondary winding 31b (therefore, the connection line L3 that is the reference connection line). )It is connected to the.

  More specifically, as shown in FIG. 24, the power source 70 includes a transformer (single transformer) 71, a diode (rectifier element) 72, a first resistor 73, and a P channel that is a switching element SW. A MOSFET (field effect transistor) 74, a second resistor 75, a third resistor (fixed or variable resistor) 76, and a fourth resistor 77 are provided.

  The transformer 71 is the same transformer as the transformer 31 described above, and includes a primary winding 31a and a secondary winding 31b, and includes the terminals T1 to T8 described above. Terminals T1 and T2 at both ends of the primary winding 31a are connected to a commercial power source that is an AC power source (for example, a power source of AC 100 (V), 60 Hz, or 50 Hz in Japan). The terminal T1 and the terminal T2 are connected to AC100V (+) and AC100V (−) of the commercial power source, respectively. Accordingly, a voltage signal AC210 (V) similar to that of the power supply 30 is generated at each terminal.

  As a result, as shown in FIG. 24, the terminals T4, T5, T6, T7 and T8 of the secondary winding 31b have alternating currents of 28, 39, 50, 175 and 210 (V) with the terminal T3 as the reference voltage. Each voltage is generated. For convenience of explanation, the position of the terminal T8 is referred to as a first position of the secondary winding 31b, and the position of the terminal T6 is referred to as a second position and a third position of the secondary winding 31b. The position of T5 is also referred to as the fourth position of the secondary winding 31b.

  The terminal T8 is connected to the cathode K of the diode 72 by a connection line L1. The anode A of the diode 72 is connected to the point P71 via a first resistor 73 inserted in series with the connection line L1. The point P71 is connected to the lower electrode 12 of the electron emitter 10. In other words, the point P71 is connected to the lower electrode 12 side of the electron emission portion EP.

  The terminal T6 is connected to the source S of the MOSFET 74 by a connection line L71. The drain D of the MOSFET 74 is connected to the point P71 via a second resistor 75 inserted in series with the connection line L71.

  The terminal T5 is connected to the gate G of the MOSFET 74 through the fourth resistor 77. A point P 72 between the source S of the MOSFET 74 and the terminal T 6 is connected to a point P 73 between the fourth resistor 77 and the gate G of the MOSFET 74 via the third resistor 76. Accordingly, the potential at the point P73 is a potential obtained by dividing the potential at the terminal T6 and the potential at the terminal T5 by the voltage dividing circuit BC including the third resistor 76 and the fourth resistor 77.

  As a result, the AC voltage AC50 (V) appearing at the terminal T6 (third position of the secondary winding 31b) and the AC appearing at the terminal T5 (fourth position of the secondary winding 31b) appear at the gate G of the MOSFET 74. A voltage proportional to the difference voltage from the voltage AC39 (V) is applied. In the MOSFET 74, when the potential of the gate G becomes lower than a predetermined threshold voltage with respect to the potential of the source S, the drain D and the source S are electrically connected (also referred to as “MOSFET 74 is turned on”).

  The terminal T3 is connected to the upper electrode 14 of the electron emitter 10 (on the upper electrode 14 side of the electron emitter EP) by a connection line L3 which is a reference connection line.

  Next, the operation of the power supply 70 configured as described above will be described with reference to FIGS. Also in the following, the power supply voltage (drive voltage Vin) is the potential at point P71 (power supply voltage = potential at point P71−potential at terminal T3) when the reference connection line L3 (potential at terminal T3) is the reference potential. ). In FIG. 25A, a solid curve CL1 is a power supply voltage, a dashed-dotted curve CL3 is a large AC voltage AC210 (V) appearing at a terminal T8, and a dashed-two dotted curve CL4 is a small appearing at a terminal T6. AC voltage AC50 (V) on the side is shown. Further, a curve CL10 in FIG. 25B shows the gate-source voltage of the MOSFET 74 (potential of the gate G when the potential of the source S is used as a reference), and a curve CL11 in FIG. Current is shown.

  First, it is assumed that electrons are not accumulated near the upper portion of the emitter section 13 at time t0 in FIG. Further, it is assumed that AC210 (V) and AC50 (V) appearing at the terminals T8 and T6 at time t0 are both 0 (V). AC210 (V) and AC50 (V) gradually increase in a sinusoidal form from 0 (V) after time t0.

  On the other hand, at time t0, as shown in FIG. 25B, the gate-source voltage is also 0 (V). Therefore, the MOSFET 74 is off (non-conducting, interrupted state). The gate-source voltage gradually decreases in a sine wave shape at time t0. For this reason, at time t1, the absolute value of the gate-source voltage becomes larger than the absolute value of the negative threshold voltage of the MOSFET 74. As a result, the MOSFET 74 is turned on (a state in which conduction and current passage are allowed).

  At this time, the potential of the terminal T6 where AC50 (V) appears is a positive potential. On the other hand, the potential on the lower electrode 12 side of the electron emission portion EP is a negative potential as described later. Accordingly, the current I72 flows from the terminal T6 through the MOSFET 74 (between the source S and the drain D of the MOSFET 74) to the lower electrode 12 side of the electron emission portion EP. Thereby, the potential of the terminal T6 (the voltage of AC50 (V) that is an AC voltage appearing at the terminal T6) is applied to the point P71 on the lower electrode 12 side of the electron emission portion EP. In other words, since AC50 (V) is applied to the electron emission part EP after time t1, the power supply voltage changes sinusoidally along AC50 (V).

  From time t1 to time t2 when AC50 (V) reaches the positive peak, AC50 (V) increases in a sine wave shape. As a result, a positive voltage whose absolute value gradually increases is applied to the lower electrode side 12 of the electron emission portion EP. In other words, the potential on the upper electrode 14 side with respect to the lower electrode 12 of the electron emission portion EP is a negative potential whose absolute value gradually increases. As a result, the negative polarization inversion described above occurs after time t1 and electrons are accumulated in the emitter section 13.

  The accumulation of electrons in the emitter section 13 is substantially completed by time 2. Therefore, in the power source 70, the potential of the lower electrode 12 becomes higher than the potential of the upper electrode 14 during a period from when the electrons are not accumulated in the emitter section 13 until at least the electrons are accumulated in the emitter section 13. Thus, the second power supply voltage whose absolute value increases sinusoidally is generated as the power supply voltage, and the power supply voltage is applied to the electron emission part EP.

  After time t2, AC50 (V) gradually decreases in a sine wave shape. At this time, the potential at the terminal T6 is lower than the potential at the point P71 (the potential on the lower electrode 12 side of the electron emission portion EP). Thereby, the current continues to flow from the lower electrode 12 side of the electron emission portion EP toward the terminal T6 through the parasitic diode of the MOSFET 74. As a result, the power supply voltage applied to the electron emitter EP (that is, the second power supply voltage AC50V) decreases. In addition, in order to block the current from the drain D to the source S due to the parasitic diode of the MOSFET 74, the direction from the MOSFET 74 to the second resistor 75 is defined as the forward bias direction in the connection line L1 between the MOSFET 74 and the second resistor 75. May be inserted in series.

  Thereafter, at time t3, as shown in FIG. 25B, the absolute value of the gate-source voltage becomes smaller than the absolute value of the negative threshold voltage of the MOSFET 74. As a result, the MOSFET 74 is turned off (non-conducting and does not allow current to pass). However, also in this case, a current from the drain D to the source S flows due to the parasitic diode of the MOSFET 74.

  Next, at time t4, the voltage (AC210 (V), AC50 (V), etc.) generated by transforming the voltage generated by the commercial power supply changes from a positive voltage to a negative voltage. After the time t4, the potential at the terminal T8 at which AC210 (V) appears becomes a negative potential. On the other hand, the potential on the lower electrode 12 side of the electron emission portion EP is 0 at time t4. Therefore, after time t4, the diode 72 is biased in the forward direction, and thus allows the forward current I71 to pass therethrough.

  Thereby, the potential of the terminal T8 (the voltage of AC210 (V) that is an AC voltage appearing at the terminal T8) is applied to the point P71 on the lower electrode 12 side of the electron emission portion EP. In other words, after time t4, a negative voltage AC210 (V) whose absolute value gradually increases in a sine wave shape is applied to the lower electrode side 12 of the electron emission portion EP. Therefore, the potential on the upper electrode 14 side with respect to the lower electrode 12 of the electron emission portion EP is a positive potential whose absolute value gradually increases. As a result, positive polarization reversal occurs in the emitter section 13, whereby electrons accumulated in the vicinity of the upper portion of the emitter section 13 are emitted upward through the fine through hole 14 a of the upper electrode 14.

  When further time elapses from time t4 to time t5, the emission electron current indicated by the curve CL5 in FIG. 25C becomes maximum. In other words, the power source 70 has a unit per unit time during which at least the electrons accumulated in the emitter 13 are emitted through the fine through-holes 14a from when the electron-emitting device 10 has accumulated electrons in the emitter 13 (time t4). The first power supply voltage whose absolute value changes in a sine wave shape so that the potential of the upper electrode 14 becomes higher than the potential of the lower electrode 12 during the period up to the time point (time t5) when the electron emission amount is the maximum amount of Generated as a power supply voltage, the first power supply voltage is applied to the electron emission part EP.

  When time elapses from time t5 and reaches time t6, AC210 (V) has a negative peak. Therefore, after time t6, the potential at the point P71 (the potential on the lower electrode 12 side of the electron emission portion EP) becomes lower than the potential at the terminal T8. Therefore, the diode 72 is biased in the reverse direction and becomes a non-conduction (cutoff) state. As a result, the power supply voltage does not change with AC 210 (V) and is substantially maintained at the value at that time. It should be noted that substantially all of the electrons accumulated in the vicinity of the upper portion of the emitter section 13 are released by a time point slightly past the time t6.

  Then, after time t7 when the voltage (AC210 (V), AC50 (V), etc.) generated by transforming the voltage generated by the commercial power supply changes from a negative voltage to a positive voltage, it is time t8. As shown in FIG. 25B, the absolute value of the gate-source voltage becomes larger than the absolute value of the negative threshold voltage of the MOSFET 74. As a result, the MOSFET 74 is turned on again.

  At this time, the potential of the terminal T6 where AC50 (V) appears is a positive potential. On the other hand, the potential on the lower electrode 12 side of the electron emission portion EP is a negative potential ("about -300 (V)" which is the peak value of AC210V). Therefore, the current I72 passes through the MOSFET 74 from the terminal T6. It flows to the lower electrode 12 side of the electron emission part EP. Thereby, at a point P71 on the lower electrode 12 side of the electron emission part EP, the potential of the terminal T6 (AC50 (V AC which is an AC voltage appearing at the terminal T6) Then, the operation after time t1 described above is repeated.

  As described above, the power supply 70 of the electron emission device according to the second embodiment also includes at least the electrons accumulated in the emitter 13 since the electron emitter 10 has accumulated electrons in the emitter 13. The absolute value in a sinusoidal shape so that the potential of the upper electrode 14 becomes higher than the potential of the lower electrode 12 during a period (time t4 to t5) until the amount of electron emission per unit time when it is emitted through 14a becomes maximum. AC210 (V), which is the first power supply voltage Vin1 that changes, is generated as the power supply voltage Vin.

  In addition, the power source 70 has a lower period (time t1 to t2 to t4) from when the electron-emitting device 10 is not accumulating electrons in the emitter section 13 until at least the electrons are accumulated in the emitter section 13. AC50 (V), which is the second power supply voltage Vin2, whose absolute value increases sinusoidally so that the potential of the electrode 12 becomes higher than the potential of the upper electrode 14, is generated as the power supply voltage Vin. Therefore, the same effect as that of the power supply 30 of the first embodiment can be obtained.

  The power source 70 includes a switching element SW (MOSFET 74) that switches application states of the first power source voltage and the second power source voltage to the electron emission unit. Thereby, the structure of the power supply 70 is simplified.

  Furthermore, the power source 70 uses a single AC power source (commercial power source) that generates an AC voltage that changes sinusoidally, and a voltage that becomes the first power source voltage by converting the AC voltage generated by the AC power source. A transformer 71 that generates AC 210 (V) and a voltage AC 50 (V) as the second power supply voltage is provided.

  Therefore, by preparing only one AC power supply, the first power supply voltage and the second power supply voltage whose amplitudes are different from each other and change sinusoidally can be easily generated. It is also possible to use a commercial power source as a power source for the electron-emitting device.

More specifically, the power supply 70 has the following characteristics.
(1) The power source 70 uses a commercial power source that is a single AC power source that generates an AC voltage that changes in a sinusoidal shape.
(2) The power supply 70 has a primary winding 31a and a secondary winding 31b, and applies an alternating voltage generated in a sine wave generated by the single alternating-current power supply to the primary winding 31a. The potential difference between the reference position (terminal T3) of the secondary winding and the first position (terminal T8) of the secondary winding 31b is taken out as a voltage AC210 (V) for generating the first power supply voltage. A potential difference between the reference position (terminal T3) of the secondary winding 31b and the second position (terminal T6) of the secondary winding 31b is taken out as a voltage AC50 (V) for generating the second power supply voltage. One transformer 71 is provided.

(3) The power source 70 includes a reference connection line L3 that connects the upper electrode 14 side of both ends of the electron emission portion EP to the reference position (terminal T3) of the secondary winding 31b, and both ends of the electron emission portion EP. A first connection line L1 that connects the lower electrode 12 side to the first position (terminal T8) of the secondary winding 31b, and a first connection line L1 that is interposed in series with the first connection line L1. A rectifying element 72 biased in the forward direction when the potential at the position (terminal T8) is lower than the potential on the lower electrode 12 side of both ends of the electron emission portion EP.

(4) The power supply 70 includes a second connection line L71 and a second connection line L71 that connect the lower electrode 12 side of both ends of the electron emission portion EP to the second position (terminal T6) of the secondary winding 31b. And a MOSFET 74 that is a switching element that is in a state of allowing the passage of current when a switching control signal is input when the passage of the current is interrupted.

  Due to these characteristics, the power source 70 includes a single AC power source (for example, a commercial power source), a single transformer 31, one rectifying element 72, and one switching element 74. The AC 210 (V) and the second power supply voltage AC 50 (V) can be generated, and these voltages can be selectively applied to the electron emission unit EP by the switching element 74 at a desired timing.

  Further, a switching control signal (voltage applied between the source S and the gate G of the MOSFET) of the MOSFET 74 which is a switching element is generated based on an AC voltage AC100 (V) generated by a single AC power supply (commercial power supply). Therefore, a power source for generating the switching control signal is not necessary.

  Further, the power source 70 is a voltage dividing circuit BC including a resistor 76 and a resistor 77 that converts the switching control signal into an AC voltage (AC voltage transformed by the transformer 71) synchronized with the AC voltage generated by the single AC power source. It is formed by dividing the pressure by. Therefore, the switching control signal can be generated with a very simple circuit. As a result, the cost of the power source 70 can be reduced.

  Further, the power source 70 is connected to the voltage AC50 (V) appearing at the third position (terminal T6) of the secondary winding 31b of the single transformer 71 and the fourth position (terminal T5) of the secondary winding 31b. The voltage difference from the appearing voltage AC39 (V) is obtained as an AC voltage synchronized with the AC voltage generated by the single AC power supply. For this reason, an extra power supply, a transformer, etc. become unnecessary, and a cheaper electron emission apparatus can be provided.

  Even in this case, it is desirable that at least one of the resistors 76 and 77 included in the voltage dividing circuit BC is a variable resistor whose resistance value can be changed by an external signal. According to this, the change timing of the first power supply voltage and the second power supply voltage can be controlled with a simple configuration by changing the resistance value of the variable resistor.

<Third Embodiment>
Next, an electron emission device according to a third embodiment of the invention will be described with reference to FIG. This electron emission device is different from the electron emission device of the first embodiment only in that the collector electrode 18 and the phosphor 19 of the electron emission device according to the first embodiment are replaced with the collector electrode 18 ′ and the phosphor 19 ′. ing. Therefore, hereinafter, this difference will be mainly described.

  In the electron emission device according to the third embodiment, the phosphor 19 ′ is formed on the back surface (the surface facing the upper electrode 14) of the transparent plate 17, and the collector electrode 18 ′ is formed so as to cover the phosphor 19 ′. ing. The collector electrode 18 ′ is formed to have a thickness that allows electrons emitted from the emitter portion 13 through the fine through hole 14 a of the upper electrode 14 to penetrate. In this case, it is desirable that the collector electrode 18 'has a thickness of 100 nm or less. The thickness of the collector electrode 18 'can be increased as the kinetic energy of the emitted electrons increases.

  Such a configuration is a configuration employed in a CRT or the like. The collector electrode 18 'functions as a metal back. Electrons emitted from the emitter section 13 through the fine through-holes 14a of the upper electrode 14 penetrate the collector electrode 18 'and enter the phosphor 19' to excite the phosphor 19 'and produce light emission. This electron emission device can achieve the following effects.

(A) When the phosphor 19 ′ is not conductive, the phosphor 19 ′ can be prevented from being charged (negatively charged). As a result, an electric field that accelerates electrons can be maintained.
(B) Since the light generated by the phosphor 19 ′ is reflected by the collector electrode 18 ′, the light can be efficiently emitted to the transparent plate 17 side (light emitting surface side).
(C) Since excessive collision of electrons with the phosphor 19 ′ can be prevented, deterioration of the phosphor 19 ′ and generation of gas from the phosphor 19 ′ can be avoided.

<Examples of materials and manufacturing methods for each component>
Next, materials of the constituent members of the electron-emitting devices and examples of manufacturing methods will be described.

(Lower electrode 12)
As described above, a conductive material is used for the lower electrode. Hereinafter, materials suitable for the lower electrode are listed.

(1) Conductor having resistance to high-temperature oxidizing atmosphere (for example, simple metal or alloy)
Example) High melting point noble metals such as platinum, iridium, palladium, rhodium, molybdenum, etc.) Mainly composed of silver-palladium, silver-platinum, platinum-palladium, etc. alloys (2) Resistant to high-temperature oxidizing atmospheres Example of mixture of insulating ceramic and simple metal) Cermet material of platinum and ceramic material (3) Mixture of insulating ceramic and alloy having resistance to high-temperature oxidizing atmosphere (4) Carbon-based or graphite-based material

  Of these, a material mainly composed of only platinum or a platinum-based alloy is very preferable. In addition, when adding a ceramic material in an electrode material, about 5-30 volume% is suitable for the ratio of the added ceramic material. Further, a material similar to the material of the upper electrode 14 described later may be used. The lower electrode is preferably formed by a thick film forming method. The thickness of the lower electrode is preferably 20 μm or less, more preferably 5 μm or less.

(Emitter part 13)
As the dielectric constituting the emitter portion, a dielectric having a relatively high relative dielectric constant (for example, a relative dielectric constant of 1000 or more) can be employed as described above. Hereinafter, substances suitable for the emitter part will be listed.

(1) Barium titanate, lead zirconate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead magnesium tantalate, lead nickel tantalate, lead antimony stannate, lead titanate, Magnesium lead tungstate, lead cobalt niobate, etc. (2) Ceramics containing any combination of substances described in (1) above

(3) The ceramic described in (2) above, further added with an oxide such as lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, etc., described in (2) above Ceramics added with a combination of any of these oxides, or further appropriately added with other compounds (4) The main component has 50% or more of the substance described in (1) above material

  For example, for a binary nPMN-mPT of lead magnesium niobate (PMN) and lead titanate (PT) (where n and m are mole ratios), the PMN mole ratio is increased. As a result, the Curie point can be lowered and the relative dielectric constant at room temperature can be increased. In particular, nPMN-mPT in which n = 0.85 to 1.0 and m = 1.0-n has a relative dielectric constant of 3000 or more, and is thus very preferable as a material for the emitter portion. For example, nPMN-mPT with n = 0.91 and m = 0.09 has a relative dielectric constant of 15000 at room temperature, and nPMN-mPT with n = 0.95 and m = 0.05 has a relative dielectric constant of 20000 at room temperature. It becomes.

  Also, for example, for a ternary PMN-PT-PZ of lead magnesium niobate (PMN), lead titanate (PT) and lead zirconate (PZ), the relative dielectric constant can be increased by increasing the molar ratio of PMN. Can be increased. Furthermore, in this ternary system, the relative dielectric constant can be increased by using a composition near the morphotropic phase boundary (MPB) of tetragonal and pseudocubic or tetragonal and rhombohedral. it can.

  For example, when PMN: PT: PZ = 0.375: 0.375: 0.25, the relative dielectric constant is 5500, and when PMN: PT: PZ = 0.5: 0.375: 0.125, the relative dielectric constant is Thus, PMN-PT-PZ having such a composition is particularly preferable as a material for the emitter portion.

  Furthermore, it is preferable to improve the dielectric constant by mixing a metal such as platinum into these dielectrics within a range in which insulation can be ensured. In this case, for example, 20% by weight of platinum may be mixed in the dielectric.

  For the emitter portion, a piezoelectric / electrostrictive layer, an antiferroelectric layer, or the like can be further used. When a piezoelectric / electrostrictive layer is used for the emitter portion, examples of the piezoelectric / electrostrictive layer include lead zirconate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead magnesium tantalate. And ceramics containing nickel tantalate, lead antimony stannate, lead titanate, barium titanate, lead magnesium tungstate, lead cobalt niobate and the like, or any combination thereof.

  As a matter of course, the emitter part may be one containing 50% by weight or more of the above compound as a main component. Among the ceramics, a ceramic containing lead zirconate is most frequently used as a constituent material of the piezoelectric / electrostrictive layer constituting the emitter portion.

Further, when the piezoelectric / electrostrictive layer is composed of ceramics, the ceramics may further include oxides such as lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, or any of these. A combination of the above or other compounds as appropriate may be used. Further, a ceramic obtained by adding SiO ₂ , CeO ₂ , Pb ₅ Ge ₃ O ₁₁ or any combination thereof to the ceramic may be used. Specifically, PT-PZ-PMN system piezoelectric material SiO ₂ and 0.2 wt%, or a CeO ₂ 0.1 wt%, or Pb ₅ Ge ₃ O ₁₁ by the addition 1 to 2 wt% materials are preferred.

  More specifically, for example, it is preferable to use a ceramic containing, as a main component, a component composed of lead magnesium niobate, lead zirconate, and lead titanate, and further containing lanthanum or strontium.

  The piezoelectric / electrostrictive layer may be dense or porous. In the case of a porous material, the porosity is preferably 40% or less.

  When an antiferroelectric layer is used for the emitter section 13, the antiferroelectric layer is mainly composed of lead zirconate, a component composed mainly of lead zirconate and lead stannate, Furthermore, what added lanthanum oxide to lead zirconate, and what added lead zirconate and lead niobate to the component which consists of lead zirconate and lead stannate are desirable.

  The antiferroelectric layer may be porous. In the case of a porous material, the porosity is desirably 30% or less.

Furthermore, strontium bismuthate tantalate (SrBi ₂ Ta ₂ O ₉ ) is suitable for the emitter part because it has low polarization reversal fatigue. Such a material with low polarization reversal fatigue is a layered ferroelectric compound and is represented by the general formula (BiO ₂ ) ²⁺ (A _m-1 B _m O _{3m + 1} ) ²⁻ . Here, the ions of metal A are Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Pb ²⁺ , Bi ³⁺ , La ^3+, etc., and the ions of metal B are Ti ⁴⁺ , Ta ⁵⁺ , Nb ^{5+ and the} like. Furthermore, it is possible to make semiconductors by adding additives to barium titanate, lead zirconate, and PZT piezoelectric ceramics. In this case, since an uneven electric field distribution is provided in the emitter section 13, the electric field can be concentrated near the interface with the upper electrode that contributes to electron emission.

  Also, the firing temperature of the emitter section 13 can be lowered by mixing the piezoelectric / electrostrictive / antiferroelectric ceramic with a glass component such as lead borosilicate glass or other low melting point compound (for example, bismuth oxide). Can do.

  In addition, when the emitter part is composed of piezoelectric / electrostrictive / antiferroelectric ceramics, the emitter part is a sheet-like molded body, a sheet-like laminate, or a laminate or bonded to another supporting substrate. Can be created from.

  Further, if the emitter part is formed of a material having a high melting point or a high evaporation temperature by using a lead-free material for the emitter part, an emitter part that is not easily damaged by the collision of electrons or ions can be obtained.

  In addition, the emitter part includes various thick film forming methods such as a screen printing method, a dipping method, a coating method, an electrophoresis method, an aerosol deposition method, and a powder jet deposition method, an ion beam method, a sputtering method, a vacuum deposition method, It can be formed by various thin film forming methods such as ion plating, chemical vapor deposition (CVD), and plating. In particular, it is possible to form a film at a low temperature of 700 ° C. or 600 ° C. or less by forming a powdered piezoelectric / electrostrictive material as an emitter portion and impregnating it with glass or sol particles having a low melting point. it can.

(Upper electrode 14)
For the upper electrode, an organic metal paste (for example, a material such as a platinum resinate paste) that can obtain a thin film after firing is used. As the material of the upper electrode, an oxide electrode that suppresses polarization reversal fatigue or a material in which an oxide electrode that suppresses polarization reversal fatigue is mixed with, for example, a platinum resinate paste is suitable. Examples of oxide electrodes that suppress polarization reversal fatigue include ruthenium oxide (RuO ₂ ), iridium oxide (IrO ₂ ), strontium ruthenate (SrRuO ₃ ), La _1-x Sr _x CoO ₃ (for example, x = 0. 3 or 0.5), La _1-x Ca _x MnO ₃ (eg, x = 0.2), La _1-x Ca _x Mn _1-y Co _y O ₃ (eg, x = 0.2, y = 0. 05).

  In addition, it is preferable to use an aggregate of scaly substances (eg, graphite) or an aggregate of conductive substances containing scaly substances for the upper electrode. Since the aggregate of such substances originally has a portion where the scale and the scale are separated from each other, the portion can be used as the fine through hole of the upper electrode without performing a heat treatment such as firing. Can be used. Further, an organic resin and a metal thin film may be formed in this order on the emitter portion and then fired, and the organic resin may be burned to form fine through holes in the metal thin film, thereby forming the upper electrode.

  The upper electrode uses the above-mentioned materials, and various thick film forming methods such as screen printing, spraying, coating, dipping, coating, electrophoresis, etc., sputtering method, ion beam method, vacuum deposition method, ion plating method, chemical method It can be formed by an ordinary film forming method using various thin film forming methods such as vapor deposition (CVD) and plating.

  As described above, the electron emission device according to each embodiment of the present invention uses the power supply 30 or the power supply 70 having a simple circuit to reduce power consumption or avoid unnecessary electron emission. Can do.

  Further, each of the electron emission devices turns off the collector electrode when unnecessary electron emission may occur, and turns on the collector electrode when electron emission is necessary. Therefore, this electron-emitting device is a display that can give sufficient energy to the normally emitted electrons while avoiding unnecessary electron emission, and can provide a good image. Further, even if the upper electrode 14 and the collector electrode 18 are in a plasma state, the collector electrode 18 is intermittently turned off, so that the plasma state can be extinguished. As a result, it is possible to avoid the continuous generation of large light emission due to the continued plasma state.

  Further, by adopting the focusing electrode, electrons are emitted from the upper electrode in a substantially upward direction, so that the distance between the upper electrode and the collector electrode can be increased. As a result, dielectric breakdown between the upper electrode and the collector electrode can be reduced or avoided. Further, since the possibility of dielectric breakdown between the upper electrode and the collector electrode is reduced, the first collector voltage V1 (Vc) applied to the collector electrode 18 is increased during the period when the collector electrode 18 is turned on. Can do. As a result, a large energy can be imparted to the electrons that reach the phosphor, so that the brightness of the display can be improved.

  In addition, this invention is not limited to said each embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, as shown in FIG. 27, the focusing electrodes 16 are formed not only between the upper electrodes 14 adjacent to each other in the X-axis direction but also between the upper electrodes 14 adjacent to each other in the Y-axis direction in plan view. May be.

  According to this, the electrons emitted from the upper electrode 14 of a certain element do not reach the phosphor above the upper electrode 14 of another element adjacent in the X-axis direction. Therefore, the color purity can be maintained satisfactorily. Further, in this example, since the focusing electrode 16 is formed between the upper electrodes 14 of two elements adjacent to each other in the Y-axis direction, electrons emitted from a certain upper electrode 14 are adjacent in the Y-axis direction. The phosphor above the upper electrode 14 does not reach. As a result, it is possible to avoid bleeding of the image pattern.

  Further, as shown in FIG. 28, the electron-emitting device has four elements (thus, four upper electrodes 14, ie, a first upper electrode 14-1 and a second upper electrode 14-in one substantially square pixel PX. 2, the third upper electrode 14-3, the fourth upper electrode 14-4), and the focusing electrode 16 may be provided. In this case, for example, a green phosphor (not shown) is disposed immediately above the first upper electrode 14-1, and a red phosphor (not shown) is directly above the second upper electrode 14-2 and the fourth upper electrode 14-4. A blue phosphor (not shown) is disposed immediately above the third upper electrode 14-3. The focusing electrode 16 is formed around each upper electrode 14 so as to surround each upper electrode 14. According to this, since the electrons emitted from the upper electrode 14 of a certain element reach only the phosphor disposed immediately above the upper electrode 14, the color purity is maintained well and the blurring of the image pattern is avoided. be able to.

  Furthermore, as shown in FIGS. 29 and 30, another electron emission device 70 according to the present invention arranges completely independent elements comprising a lower electrode 72, an emitter portion 73 and an upper electrode 74 on the substrate 11. And a structure in which each element is filled with an insulator 75, and a focusing electrode 76 is formed between the upper electrodes 74 of elements adjacent to each other in the X-axis direction on the upper surface of the insulator 75. It may be.

  The electron emission device 70 configured in this manner can emit electrons at an independent timing from each element or simultaneously. Therefore, an independent collector electrode is provided above the upper electrode 74 of each element, and the collector voltage application circuit turns on or off each collector electrode according to the state of the element corresponding to each collector electrode. It may be configured.

  Moreover, you may comprise so that the voltage Vs (t) which changes with time passage may be provided to the focusing electrode 16 (76) mentioned above. In this case, for example, a negative voltage larger in magnitude in the charge accumulation period Td than in the light emission period Th may be applied to the focusing electrode 16 to more reliably suppress unnecessary electron emission in the charge accumulation period Td. .

  Furthermore, the focusing electrode 16 may be maintained in a floating state during the charge accumulation period Td, and a predetermined potential may be applied to the focusing electrode 16 during the light emission period Th. According to this, since it is possible to avoid the generation of a transient current caused by capacitive coupling between the focusing electrode 16 and the upper electrode 14 or between the focusing electrode 16 and the lower electrode 12, unnecessary power consumption is avoided. can do.

  In addition, in the above embodiment, in order to perform electron emission all at once, currents (collector currents) due to electrons emitted to the collector electrode 18 (or collector electrode 18 ′; the same shall apply hereinafter) flow all at once. The potential of the collector electrode 18 decreases due to a voltage drop caused by the collector resistor 51 inserted in the collector voltage application circuit 50 (collector electrode circuit). For this reason, the energy of electrons when colliding with the phosphor 19 (or phosphor 19 ', the same shall apply hereinafter) is lowered, and the luminance is lowered. If the value of the collector resistance 51 is reduced in order to prevent this decrease in luminance, damage to the collector electrode 18, the phosphor 19 or the electron-emitting device when abnormal discharge (excessive emission of electrons) occurs increases.

  Therefore, it is effective to suppress the peak value of the collector current by setting the electron emission timings of the plurality of electron-emitting devices included in the electron-emitting device to different timings among the electron-emitting devices. This can be realized, for example, by the method described below.

  Two transformers are prepared, a plurality of electron-emitting devices are divided into two groups, and each group is driven by a separate transformer (connected to a separate transformer to perform an electron emission operation). More specifically, the primary windings of the two transformers are connected to a commercial power source (single AC power source) so as to be different from each other. At this time, as shown in FIG. 21, for one transformer, AC100V (−) is connected to the terminal T1, and AC100V (+) is connected to the terminal T2. As for another transformer, AC100V (+) is connected to the terminal T1, and AC100V (-) is connected to the terminal T2. The secondary winding and the electron-emitting device are connected to each other as shown in FIG.

  In this way, electrons are emitted from the elements of each group at a timing different from each other by half the period of the power supply voltage. Therefore, the peak of the collector current can be halved as compared with the case where electrons are emitted from all the devices at once. As a result, it is possible to achieve both of ensuring the luminance and protecting the element.

  The substrate 11 is made of a material mainly composed of aluminum oxide, a material mainly composed of a mixture of aluminum oxide and zirconium oxide, soda glass, lead glass, borosilicate glass, or quartz glass. Also good.

1 is a partial cross-sectional view of an electron emission device according to a first embodiment of the present invention. It is the fragmentary sectional view which cut | disconnected the electron emission apparatus shown in FIG. 1 in a different plane. FIG. 2 is a partial plan view of the electron emission device shown in FIG. 1. FIG. 2 is an enlarged partial cross-sectional view of the electron emission device shown in FIG. 1. FIG. 2 is an enlarged partial plan view of an upper electrode shown in FIG. 1. FIG. 2 is a diagram illustrating one state of the electron-emitting device illustrated in FIG. 1. 5 is a graph showing polarization-element end voltage characteristics (QV characteristics) of the electron-emitting device shown in FIG. 1. It is a time chart for demonstrating the principle of operation of the electron emission apparatus shown in FIG. It is the figure which showed the other state of the electron-emitting element shown in FIG. It is the figure which showed the other state of the electron-emitting element shown in FIG. It is the figure which showed the other state of the electron-emitting element shown in FIG. It is the figure which showed the other state of the electron-emitting element shown in FIG. It is the figure which showed the other state of the electron-emitting element shown in FIG. It is the figure which showed the mode of the electron discharge | released by the electron emission element which is not provided with a focusing electrode. It is the figure which showed the mode of the electron discharge | released by the electron emission apparatus shown in FIG. It is the time chart which showed the drive voltage, element voltage, element current, and optical output when the conventional electron emission apparatus performed normal electron emission. It is the time chart which showed the drive voltage, element voltage, element current, and optical output when the conventional electron emission apparatus performed unnecessary (abnormal) electron emission. It is the time chart which showed the drive voltage, element voltage, element current, and optical output when the conventional electron emission apparatus performed unnecessary (abnormal) electron emission. It is the time chart which showed the drive voltage, element voltage, element current, and optical output when the conventional electron emission apparatus performed unnecessary (abnormal) electron emission. It is the block diagram which showed notionally the power supply shown in FIG. FIG. 21 is a circuit diagram of the power supply shown in FIGS. 1 and 20. FIG. 22 is a time chart showing a power supply voltage generated by the power supply shown in FIG. 21, an element end voltage of the electron-emitting device, and the like. It is a time chart for demonstrating the method to produce the voltage applied to the gate of the thyristor shown in FIG. It is a circuit diagram of the power supply which concerns on 2nd Embodiment of this invention. It is a time chart which showed the power supply voltage etc. which the power supply shown in FIG. 24 generate | occur | produces. It is a fragmentary sectional view of the electron emission apparatus which concerns on 3rd Embodiment of this invention. It is a fragmentary top view of the modification of the electron emission apparatus by this invention. It is a fragmentary top view of the other modification of the electron emission apparatus by this invention. It is a fragmentary sectional view of the other modification of the electron emission apparatus by this invention. FIG. 30 is another partial cross-sectional view of the electron emission device shown in FIG. 29. It is a fragmentary sectional view of the electron emission apparatus which is not provided with a focusing electrode. It is the time chart which showed the drive voltage (power supply voltage) and optical output in the electron emission apparatus to which this invention is not applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electron emission element, 11 ... Board | substrate, 12 ... Lower electrode, 13 ... Emitter part, 13 ... Emitter part, 14 ... Each upper electrode, 14a ... Through-hole (fine through-hole), 14 ... Upper electrode, 15 ... Insulating layer 16 ... Focusing electrode, 17 ... Transparent plate, 18 ... Collector electrode, 19 ... Phosphor, 19B ... Blue phosphor, 19R ... Red phosphor, 19G ... Green phosphor, 20 ... Protection resistor, 30 ... Power supply, 31 ... Transformer, 31a ... primary winding, 31b ... secondary winding, 32 ... diode (rectifier element), 34 ... thyristor (rectifier element, switching element), 40 ... focusing electrode potential application circuit, 50 ... collector voltage application circuit, DESCRIPTION OF SYMBOLS 70 ... Electron emission apparatus, 72 ... Lower electrode, 73 ... Emitter part, 74 ... Upper electrode, 75 ... Insulator, 76 ... Focusing electrode, EP ... Electron emission part.

Claims (11)

An emitter portion made of a dielectric, a lower electrode formed at the lower portion of the emitter portion, a plurality of fine through holes formed at the upper portion of the emitter portion so as to face the lower electrode across the emitter portion And an upper electrode formed so that a surface of the fine through-hole and facing the emitter portion is spaced apart from the emitter portion by a predetermined distance. An electron emitter,
A power supply for generating a power supply voltage to be applied to the electron emission unit;
In an electron emission device that accumulates electrons in the emitter section by the power supply voltage and emits the accumulated electrons through the fine through hole,
The power supply is
From when the electron-emitting device is in a state of accumulating electrons in the emitter section until at least the amount of electrons emitted per unit time when electrons accumulated in the emitter section are emitted through the fine through-holes is maximized. Generating, as the power supply voltage, a first power supply voltage whose absolute value changes sinusoidally so that the potential of the upper electrode is higher than the potential of the lower electrode during the period,
The potential of the lower electrode is made higher than the potential of the upper electrode during a period from when the electron-emitting device is not accumulating electrons in the emitter portion to at least accumulation of electrons in the emitter portion. An electron-emitting device configured to generate, as the power supply voltage, a second power supply voltage whose absolute value increases sinusoidally. The electron emission device according to claim 1, wherein
The electron emission portion is
An electron emission device including a protective resistor connected in series to the electron emission element. The electron-emitting device according to claim 1 or 2,
The electron emission device, wherein the amplitude of the first power supply voltage is larger than the amplitude of the second power supply voltage. The electron emission device according to claim 3, wherein
The power supply is
An electron emission device comprising a switching element for switching application states of the first power supply voltage and the second power supply voltage to the electron emission portion. The electron emission device according to claim 3, wherein
The power supply is
A voltage that becomes the first power supply voltage and a voltage that becomes the second power supply voltage are obtained by converting the AC voltage generated by the AC power supply connected to a single AC power supply that generates an AC voltage that changes in a sine wave shape. Generating transformer,
An electron emission device. The electron emission device according to claim 3, wherein
The power supply is
It has a primary winding and a secondary winding, and an AC voltage changing in a sine wave generated by a single AC power source is applied to the same side winding, and the reference position of the secondary winding and the same secondary winding are applied. A potential difference from the first position of the line is taken out as a voltage for generating the first power supply voltage, and a potential difference between the reference position of the secondary winding and the second position of the secondary winding is taken as the first position. A single transformer taking out as a voltage to generate two power supply voltages;
A reference connection line connecting the lower electrode side of both ends of the electron emission portion to a reference position of the secondary winding;
A first connection line connecting the upper electrode side of both ends of the electron emission portion with a first position of the secondary winding;
A rectifying element that is interposed in series with the first connection line and is forward-biased when the potential at the first position of the secondary winding is higher than the potential on the upper electrode side of both ends of the electron emission portion. When,
A second connection line connecting the upper electrode side of both ends of the electron emission portion with a second position of the secondary winding;
A switching element that is interposed in series with the second connection line and that is allowed to pass current when a switching control signal is input when it is in a state of blocking current passage;
An electron emission device. The electron emission device according to claim 3, wherein
The power supply is
It has a primary winding and a secondary winding, and an AC voltage changing in a sine wave generated by a single AC power source is applied to the same side winding, and the reference position of the secondary winding and the same secondary winding are applied. A potential difference from the first position of the line is taken out as a voltage for generating the first power supply voltage, and a potential difference between the reference position of the secondary winding and the second position of the secondary winding is taken as the first position. A single transformer taking out as a voltage to generate two power supply voltages;
A reference connection line connecting the upper electrode side of both ends of the electron emission portion to a reference position of the secondary winding;
A first connection line connecting the lower electrode side of both ends of the electron emission portion with a first position of the secondary winding;
A rectifying element that is interposed in series with the first connection line and is forward-biased when the potential at the first position of the secondary winding is lower than the potential at the lower electrode side of both ends of the electron emission portion. When,
A second connection line connecting the lower electrode side of both ends of the electron emission portion to a second position of the secondary winding;
A switching element that is interposed in series with the second connection line and that is allowed to pass current when a switching control signal is input when it is in a state of blocking current passage;
An electron emission device. The electron emission device according to claim 6 or 7,
The power supply is
An electron emission device configured to generate the switching control signal based on an AC voltage generated by the single AC power source. The electron emission device according to claim 8, wherein
The power supply is
An electron emission device configured to form the switching control signal by dividing an AC voltage synchronized with an AC voltage generated by the single AC power source by a voltage dividing circuit including a resistor. The electron emission device according to claim 9, wherein
The AC voltage synchronized with the AC voltage generated by the single AC power supply appears at the fourth position of the secondary winding and the voltage appearing at the third position of the secondary winding of the single transformer. An electron-emitting device that is the voltage that is the difference from the voltage. The electron-emitting device according to claim 9 or 10,
The electron emission device, wherein at least one resistor included in the voltage dividing circuit is a variable resistor.

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