JP2006261087A - Electron emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron emitting device of which possibility of emission generation of unnecessary electrons is low. <P>SOLUTION: The electron emitting device 10 is provided with an element consisting of a lower electrode 12, an emitter part 13 consisting of dielectric, and a plurality of upper electrodes 14 having minute through-holes, and a power source 21s, and a drive voltage creating circuit 21 including the circuit to create the voltage generated between the lower electrode and the upper electrode by the power source. Then, when the electrons accumulated to the emitter part are emitted, the power source generates voltages gradually increasing toward a second voltage from a first voltage. When electron accumulated in the emitter part is made to be released, the power source generates voltage gradually increasing from the first voltage toward the second voltage and generates voltages gradually decreasing toward the first voltage from the second voltage. By this, sudden changes of the element voltage and excess element current are suppressed, and unnecessary electron emission is evaded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electron emission device including an emitter made of a dielectric, a lower electrode formed below the emitter, and an upper electrode formed above the emitter.

Conventionally, an emitter portion made of a dielectric, a lower electrode (lower electrode layer) formed on the lower surface of the emitter portion, and an upper electrode (upper electrode layer) formed on the upper surface of the emitter portion and having many fine through holes There is known an electron emission device that emits electrons from fine through holes of the upper electrode by applying a high-voltage pulse between the upper electrode and the lower electrode to invert the polarization of the dielectric (for example, (See Patent Document 1).
Japanese Patent No. 3160213 (Claims 1, paragraphs 0016 to 0019, FIGS. 2 and 3)

  Such a device can be applied to a display. For example, as shown in FIG. 40, the electron emission device applied to the display includes a transparent plate 17, a collector electrode 18, and a phosphor 19 at a position facing the upper electrode 14. Then, the electron emission device irradiates the phosphor 19 with electrons emitted from the emitter portion 13 through a fine through hole (not shown) formed in the upper electrode 14 so that light is emitted from the phosphor 19. It has become. The collector electrode 18 is for accelerating the emitted electrons. The electron emission device always applies a constant positive voltage Vc to the collector electrode 18.

  This control for light emission by electron emission is executed as shown in FIG. 41, for example. That is, the electron-emitting device sets the driving voltage Vin generated by the power source to apply a voltage between the upper electrode 14 and the lower electrode 12 from time t10 to time t20 to the negative first voltage Vm, and Electrons are supplied from the upper electrode 14 toward the emitter section 13 by reversing the direction of the dipole (reversing the polarization). Thereby, electrons are accumulated mainly in the vicinity of the upper portion of the emitter section 13. Next, the electron emission device immediately changes the drive voltage Vin from the first voltage Vm to the positive second voltage Vp at time t20 to reverse the polarization of the emitter section 13 again, and the coulomb repulsive force associated therewith The electrons accumulated in the vicinity of the upper part of the emitter section 13 are emitted upward. As a result, the phosphor 19 is irradiated with electrons, and the phosphor 19 emits light.

  The electron emission device repeats such an operation. That is, the electron emission device immediately changes the drive voltage Vin from the second voltage Vp to the first voltage Vm at time t30 and resumes the accumulation of electrons, and at time t40, the drive voltage Vin is changed from the first voltage Vm to the first voltage Vm. The voltage is immediately changed to 2 voltage Vp, 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 lower electrode and the upper electrode.

  However, the inventor determines that the drive voltage Vin is set to a positive second time immediately after the time t30 (when the drive voltage Vin is changed to the negative first voltage Vm in order to store electrons) or at the time t40 (to release the electrons). Immediately after the change to the voltage Vp), electrons are emitted at an unscheduled timing, and / or abnormally large light emission (extremely strong light emission) occurs due to excessive emission of electrons, etc. The inventors have found that unnecessary light emission may occur.

  The reason for this is not clear, but according to experiments, immediately after the drive voltage Vin is switched, a large inrush current flows in the emitter section, or after the polarization inversion of the emitter section is completed, between the upper electrode and the lower electrode. It is presumed that this is due to a sudden change in the actual potential difference (hereinafter also referred to as “element voltage”). Further, it is considered that the abnormal large light emission is caused by the generation of plasma between the upper electrode 14 and the collector electrode 18 to break the insulation between the upper electrode 14 and the collector electrode 18.

  This unnecessary electron emission causes a problem of deteriorating the color purity and contrast of an image displayed on the display. In addition, abnormal large light emission may cause the material forming the upper electrode 14 to scatter and destroy the upper electrode 14, or may make a hole in the emitter section 13, thereby damaging the electron emission device. This also causes a problem.

  The present invention has been made in order to cope with the above-described problems, and it is possible to reduce unnecessary electrons by appropriately controlling a voltage (driving voltage) generated by a power source and a constant of a circuit for applying the driving voltage. The purpose is to avoid the release of.

In order to achieve the above object, an electron emission device according to the present invention comprises:
A dielectric emitter, a lower electrode formed under the emitter, and an upper portion of the emitter so as to face the lower electrode across the emitter and a plurality of fine through holes are formed. An element having an upper electrode,
A driving voltage applying means including a power supply and a circuit for applying a voltage generated by the power supply between the lower electrode and the upper electrode;
It is an apparatus provided with.

And the power supply
A first voltage is generated so that a device voltage, which is a potential difference between the lower electrode and the upper electrode with respect to the potential of the lower electrode, as a predetermined negative voltage is generated from the upper electrode to the emitter section. The electrons are supplied to the emitter section and accumulated in the emitter section. After that, a voltage that gradually increases toward the second voltage is generated and accumulated in the emitter section so that the element voltage becomes a predetermined positive voltage. Electrons are emitted from the emitter.

  According to this, when the device voltage is changed to a positive predetermined voltage in order to emit electrons, the power supply generates a gradually increasing voltage. As a result, it is possible to reduce the magnitude of the inrush current flowing in the emitter immediately after the voltage generated by the power source starts to increase, and to reduce the rate of change of the element voltage after completion of the positive-side polarization inversion. it can. 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, by changing the voltage (drive voltage) generated by the power supply as described above, polarization inversion and electron emission are performed in a state where the difference between the drive voltage and the element voltage is small. The power consumption (Joule heat) in the component is reduced. As a result, since the element is not heated, it can be avoided that the characteristics of the emitter section are changed by heating. Furthermore, since the element temperature does not increase, gasification of a substance adsorbed on the element can be avoided. As a result, generation of plasma is avoided, so that excessive emission of electrons (generation of large light emission) and damage to the element due to ion bombardment can be avoided.

In this case, the power supply is
After the first voltage is generated, the device voltage is between the negative predetermined voltage and the positive predetermined voltage without further accumulating electrons in the emitter section and releasing electrons from the emitter section. A voltage that increases from the first voltage toward the third voltage is generated so as to be an intermediate voltage, and then increases from the first voltage toward the second voltage from the first voltage toward the second voltage. It is preferable to generate a voltage that increases more slowly than when doing so.

  Even when the element voltage becomes the intermediate voltage, the polarization of the emitter section is not reversed, so that no more electrons are accumulated in the emitter section and no electrons are emitted from the emitter section. Further, when the device voltage is changed from the negative predetermined voltage to the intermediate voltage, unnecessary electron emission does not occur even if the voltage generated by the power supply is suddenly changed. Therefore, if configured as described above, it is possible to shorten the time from the accumulation of electrons to the regular emission of electrons while avoiding unnecessary emission of electrons.

In this case, the power supply is
The voltage increase start time in the period from the voltage increase start time at which generation of the voltage gradually increasing toward the second voltage to the second voltage arrival time at which the voltage reaches the second voltage. It is preferable to generate a voltage that gradually increases during a period from the time when the positive polarity reversal is completed to the time when the reversal of the polarization of the emitter portion is substantially completed.

  Positive side where the inversion of the polarization of the emitter section is substantially completed from the voltage increase start point at which the power source starts generating a voltage that gradually increases toward the second voltage (from the first voltage or the third voltage). The period until the completion of polarization inversion is a period in which the inrush current flowing through the emitter section becomes very large. Therefore, as described above, the magnitude of the inrush current can be effectively reduced by increasing the voltage generated by the power supply most slowly during this period. As a result, unnecessary emission of electrons due to the inrush current can be avoided. Moreover, since the voltage generated by the power source reaches the second voltage when the voltage on the positive side reaches the second voltage until the second voltage is reached, the voltage can be gradually increased at a relatively large voltage change rate. It is also possible to shorten the voltage increase period (period for performing the electron emission operation) from the time point to the time when the second voltage is reached.

On the other hand, the power supply
During the period from the voltage increase start time at which generation of the voltage gradually increasing toward the second voltage to the second voltage arrival time at which the voltage reaches the second voltage, the polarization of the emitter section It is also possible to generate a voltage that gradually increases during the period from the time when the positive-side polarization reversal is completed to the time when the second voltage is reached.

  Depending on the element itself or other countermeasures, unnecessary electron emission due to sudden change in element voltage after completion of positive side polarization reversal occurs more frequently than unnecessary electron emission due to inrush current. There are things to do. Therefore, as described above, unnecessary electron emission can be effectively avoided by increasing the voltage generated by the power source most slowly during the period from the completion of positive-side polarization reversal to the arrival of the second voltage. . Further, since the voltage generated by the power source can be gradually increased at a relatively large voltage change rate from the voltage increase start time to the positive side polarization reversal completion time, the voltage from the voltage increase start time to the second voltage arrival time The increase period (period for performing the electron emission operation) can also be shortened.

Other electron emission devices according to the present invention include:
A dielectric emitter, a lower electrode formed under the emitter, and an upper portion of the emitter so as to face the lower electrode across the emitter and a plurality of fine through holes are formed. An element having an upper electrode,
A driving voltage applying means including a power supply and a circuit for applying a voltage generated by the power supply between the lower electrode and the upper electrode;
An electron emission device comprising:
The power supply is
A second voltage is generated and stored in the emitter section so that the element voltage, which is a potential difference between the lower electrode and the upper electrode with respect to the potential of the lower electrode, is a predetermined positive voltage. The electrons are emitted from the emitter, and then a voltage that gradually decreases toward the first voltage is generated so that the element voltage becomes a predetermined negative voltage, and the electrons are supplied from the upper electrode to the emitter. The electrons are stored in the emitter section.

  According to this, when the element voltage is changed to a negative predetermined voltage in order to accumulate electrons, the power source generates a gradually decreasing voltage. As a result, it is possible to reduce the magnitude of the inrush current flowing in the emitter immediately after the voltage generated by the power source starts to decrease, and to reduce the rate of change of the element voltage after completion of the negative polarization inversion. it can. 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 abrupt device voltage immediately after completion of negative side polarization inversion Unnecessary emission of electrons (unnecessary light emission) due to the change can be avoided.

  Furthermore, by changing the voltage (drive voltage) generated by the power supply as described above, polarization inversion and electron accumulation are performed in a state where the difference between the drive voltage and the element voltage is small. The power consumption (Joule heat) in the resistance component is reduced. As a result, since the element is not heated, it can be avoided that the characteristics of the emitter section are changed by heating. Furthermore, since the element temperature does not increase, gasification of a substance adsorbed on the element can be avoided. As a result, generation of plasma is avoided, so that excessive emission of electrons (generation of large light emission) and damage to the element due to ion bombardment can be avoided.

In this case, the power supply is
After generating the second voltage, the element voltage is intermediate between the negative predetermined voltage and the positive predetermined voltage without accumulating electrons in the emitter section and emitting electrons from the emitter section. When a voltage that decreases from the second voltage to the third voltage is generated so as to be a voltage, and then decreases from the second voltage to the third voltage from the third voltage toward the first voltage. It is preferable to be configured to generate a voltage that decreases more slowly.

  Even if the element voltage becomes the intermediate voltage, no electrons are accumulated in the emitter section, and no electrons are emitted from the emitter section. Further, unnecessary electron emission does not occur even if the voltage generated by the power supply is suddenly changed when the element voltage is changed to the intermediate voltage. Therefore, when configured as described above, it is possible to shorten the time from the emission of electrons to the accumulation of electrons.

In this case, the power supply is
In the period from the voltage decrease start time at which generation of the voltage gradually decreasing toward the first voltage to the first voltage arrival time at which the voltage reaches the first voltage, the voltage decrease start time It is preferable to generate a voltage that gradually decreases during a period from the time when the negative polarization inversion of the emitter section is substantially completed to the time when the negative side polarization inversion is completed.

  The negative side where the inversion of the polarization of the emitter section is substantially completed from the voltage decrease start point at which the power source starts generating a voltage that gradually decreases toward the first voltage (from the second voltage or the third voltage). The period until the completion of polarization reversal is a period in which the inrush current flowing through the emitter portion becomes very large. Therefore, as described above, the magnitude of the inrush current can be effectively reduced by reducing the voltage generated by the power supply most slowly during this period. As a result, unnecessary emission of electrons due to the inrush current can be avoided. In addition, since the voltage generated by the power source reaches the first voltage when the negative side polarization reversal is completed, the voltage can be gradually decreased with a relatively large voltage change rate. It is also possible to shorten the voltage decrease period (the period for performing the electron storage operation) from the voltage decrease start time to the first voltage arrival time.

On the other hand, the power supply
The polarization of the emitter section during a period from a voltage decrease start time at which generation of the voltage gradually decreasing toward the first voltage starts to a first voltage arrival time at which the voltage reaches the first voltage. It may be configured to generate a voltage that gradually decreases in the period from the time when the negative side polarization reversal is completed to the time when the first voltage is reached.

  Depending on the element itself or other countermeasures, unnecessary electron emission due to sudden change in element voltage after completion of negative polarization reversal occurs more frequently than unnecessary electron emission due to inrush current. There are things to do. Therefore, as described above, unnecessary electron emission can be effectively avoided by decreasing the voltage generated by the power source most slowly during the period from the completion of negative side polarization reversal to the arrival of the first voltage. . In addition, since the voltage can be gradually decreased at a relatively large voltage change rate from the voltage decrease start time to the negative side polarization reversal completion time, the voltage from the voltage decrease start time to the first voltage arrival time The decrease period (period for performing the operation of electron accumulation) can be shortened.

  By the way, when it is necessary to repeatedly emit electrons as in a display device, the power supply is configured to repeatedly generate the first voltage and the second voltage.

At this time, the drive voltage applying means is
A first period from a voltage decrease start time at which generation of the voltage decreasing toward the first voltage starts to a time point when the negative polarization inversion of the emitter section is substantially completed during the decrease of the voltage. Circuit elements inserted into the circuit in a period;
A circuit element inserted into the circuit in a second period from completion of the negative polarization inversion to completion of accumulation of electrons in the emitter section; and
A third period from a voltage increase start time at which generation of the voltage increasing toward the second voltage starts to a positive polarization inversion completion point at which the polarization inversion of the emitter section is substantially completed during the increase of the voltage. A circuit element inserted into the circuit in a period;
A circuit element that is inserted into the circuit in a fourth period from the completion of the positive side polarization reversal to the completion of electron emission from the emitter section,
Among them, it is preferable to include circuit constant setting means for setting circuit constants of the circuit by selecting the circuit elements so that at least two circuit elements are different from each other and inserting the circuit elements into the circuit.

  The first to fourth periods are periods in which unnecessary electrons can be emitted. On the other hand, the period during which unnecessary electron emission occurs frequently varies depending on the device, for example, by adding characteristics of the element itself based on the material and other means for avoiding unnecessary electron emission (for example, control of the collector electrode). . On the other hand, if a circuit element is selected and inserted into the circuit so that the constant of the circuit for connecting the power source, the upper electrode and the lower electrode is uniformly large, unnecessary electron emission can be avoided. it can.

  However, with such a configuration, the time required for the accumulation of electrons and the time required for the emission of electrons become long, and electrons cannot be emitted at a desired frequency (period). Therefore, as in the above configuration, the circuit constants in the period in which unnecessary electron emission frequently occurs according to the characteristics of the element and the circuit constants in other periods are inserted into the circuit in each period so that they are different. Select / switch the circuit element (for example, resistor). As a result, there is provided an electron emission device that can emit electrons at a desired frequency and avoid unnecessary electron emission. In this case, the above-described control for gradually changing the voltage generated by the power supply may or may not be performed.

Other electron emission devices according to the present invention include:
A dielectric emitter, a lower electrode formed under the emitter, and an upper portion of the emitter so as to face the lower electrode across the emitter and a plurality of fine through holes are formed. An element having an upper electrode,
A driving voltage applying means including a power supply and a circuit for applying a voltage generated by the power supply between the lower electrode and the upper electrode;
In an electron emission device comprising:
The power supply is
In order to supply electrons from the upper electrode to the emitter section and accumulate the electrons in the emitter section, a fourth voltage, which is a negative voltage that causes polarization inversion in the emitter section, is obtained. When the negative side polarization reversal is completed, or at a predetermined time before the completion of the negative side polarization reversal, the fifth voltage, which is a negative voltage smaller than the fourth voltage, is obtained. The electron-emitting device is configured to generate a voltage that gradually decreases toward a first voltage that is a negative voltage having a magnitude greater than that of the fifth voltage.

  According to experiments, after the negative side polarization reversal is completed, the device voltage changes rapidly, and unnecessary electron emission is frequently performed. Therefore, as in the above configuration, the power supply becomes the fourth voltage, which is a negative voltage that causes polarization reversal in the emitter section, and thereafter, when the negative side polarization reversal is completed or on the same negative side At a predetermined time before the completion of polarization reversal, the voltage becomes a fifth voltage that is a negative voltage smaller than the fourth voltage, and then a negative voltage larger than the fifth voltage. If a voltage that gradually decreases toward the first voltage is generated, the difference between the element voltage after the negative side polarization inversion and the voltage generated by the power supply becomes small, and the element voltage is the voltage generated by the power supply. It gradually changes with time. As a result, the frequency of unnecessary electron emission can be reduced. In addition, since the voltage generated by the power supply can be the negative fourth voltage having a magnitude larger than the fifth voltage until the negative side polarization inversion occurs, the time until the negative side polarization inversion is shortened. You can also. The “magnitude” of the voltage refers to the absolute value of the voltage.

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 device 10 according to the first embodiment of the present invention includes a substrate 11, a plurality of lower electrodes (lower electrode layers) 12, an emitter unit 13, and a plurality of upper electrodes (upper parts). Electrode layer) 14, insulating layer 15, and a plurality of focusing electrodes (focusing electrode layers) 16. 1 is a partial plan view of the electron emission device 10, and is a cross-sectional view of the electron emission device 10 cut along a plane along line 1-1 in FIG. 3, and FIG. 2 is along line 2-2 in FIG. It is sectional drawing which cut | disconnected the electron emission apparatus 10 in the open 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.

  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. Thus, the electron emission device 10 includes a plurality of independent electron emission elements.

  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 10 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 the electron emission device 10 (not shown). The sealed space is maintained in a substantially vacuum. Therefore, the elements of the electron emission device 10 (at least the upper part of the emitter section 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.

  In addition, as shown in FIG. 1, the electron emission device 10 includes a drive voltage applying circuit (drive voltage applying means, potential difference applying means) 21, a focusing electrode potential applying circuit (focusing electrode potential difference applying means) 22, and a collector. A voltage application circuit (collector voltage application means) 23.

  The drive voltage application circuit 21 includes a power source 21s that generates a drive voltage Vin (described later). The power source 21 s is connected to each upper electrode 14 and each lower electrode 12. That is, the drive voltage application circuit 21 includes a power source 21s and a circuit for connecting the power source 21s and each element. Further, the drive voltage applying circuit 21 is connected to the signal control circuit 100 and the power supply circuit 110, and between the upper electrode 14 and the lower electrode 12 (elements) facing each other based on a signal from the signal control circuit 100. A drive voltage Vin is applied to the.

  The focusing electrode potential application circuit 22 is connected to the focusing electrode 16 and always applies a constant negative potential (voltage) Vs to the focusing electrode 16.

  The collector voltage applying circuit 23 is a circuit for applying a predetermined voltage (collector voltage) to the collector electrode 18, and includes a resistor 23a, a switching element 23b, a constant voltage source 23c that generates a constant voltage Vc, And a switch control circuit 23d. One end of the resistor 23 a is connected to the collector electrode 18. The other end of the resistor 23a is connected to a fixed connection point of the switching element 23b. The switching element 23b is a semiconductor element such as a MOS-FET and is connected to the switch control circuit 23d.

  The switching element 23b includes two switching points in addition to the fixed connection point. The switching element 23b selectively connects either one of the two switching points and the fixed connection point in response to an instruction signal from the switch control circuit 23d. One of the two switching points is grounded, and the other is connected to the anode of the constant voltage source 23c. The cathode of the constant voltage source 23c is grounded. The switch control circuit 23d is connected to the signal control circuit 100, and performs switching control of the switching element 23b based on a signal from the signal control circuit 100. Further, the switch control circuit 23d incorporates an element voltage measurement circuit and an electron emission completion detection circuit which will be described later.

(Principle and operation of electron emission)
Next, the operation principle regarding the electron emission of the electron emission device 10 configured as described above will be described by paying attention to one element. In the following, for simplicity of explanation, the drive voltage Vin generated by the power source 21s 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 (that is, the element voltage Vka) between the lower electrode 12 and the upper electrode 14 with respect to the potential of the lower electrode 12 is maintained at a positive predetermined voltage Vp, and the emitter section The description is started from a state immediately after all the 13 electrons are emitted and the electrons are not 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 of the voltage-polarization characteristics of the emitter section 13 with the element voltage Vka on the horizontal axis and the charge Q in the vicinity of the upper electrode 14 on the vertical axis.

  In this state, the power source 21s of the drive voltage application circuit 21 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 voltage Vka decreases toward the point p3 via the point p2 in FIG. When the element 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 reverse. 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.

  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 voltage Vka rapidly changes toward the negative predetermined voltage (first voltage) Vm, and at time t10. Negative predetermined voltage Vm is obtained. 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 drive voltage application circuit 21 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 voltage Vka starts to increase. At this time, until the element voltage Vka reaches a 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. State is maintained. Thereafter, the element 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 voltage Vka starts to increase rapidly, and electrons are actively emitted. Next, at time t16, the electron emission is completed, and the element 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.

  When there are a plurality of elements, the drive voltage application circuit 21 needs to accumulate electrons by using the drive voltage Vin as the first voltage Vm only for the upper electrode 14 of the element that is to emit electrons, and to emit electrons. The drive voltage Vin is maintained at a value of “0” for the upper electrodes 14 that are not present, and then the drive voltage Vin is changed to the second voltage Vp simultaneously (simultaneously) for all the upper electrodes 14. It has become. As a result, electrons are emitted only from the upper electrode 14 (fine through hole 14a) of the element that has accumulated the electrons in the emitter section 13. Therefore, polarization inversion does not occur in the emitter section 13 near the upper electrode 14 that does not need to emit 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 emission device 10 according to the present 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 10 that operates as described above, as understood from the collector current (the amount of electrons that reach the collector electrode per unit time) shown in FIG. Beginning, 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 driving voltage Vin, element voltage Vka, element current Ik, and optical output APD when normal electron emission (light emission) is performed when the driving voltage Vin is changed to a rectangular wave shape. Again, a description will be given 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, 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 positive side polarization reversal occurs at time t2 to time t3 immediately after time t1, the element voltage Vka increases rapidly from time t1 to time t2 and then gradually increases to time t3. The element voltage Vka increases in the period up to time t4 when the positive-side polarization reversal ends at time t3 (exceeds the positive coercive electric field voltage), and after the time t4, the element voltage Vka Matching voltage. 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 side polarization reversal occurs from time t6 to time t7 immediately after time t5, the element voltage Vka decreases relatively rapidly from time t5 to time t6 and then becomes substantially constant from time t7. The element voltage Vka sharply decreases in the period up to time t8 when the negative side polarization reversal ends at time t7 (exceeds the negative coercive field voltage), and the second voltage of the drive voltage Vin after time t8. The voltage matches 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 voltage Vka changes abruptly immediately after the positive side polarization inversion of the emitter section 13 is completed (at the time when the positive coercive field voltage is exceeded) (temporal change rate of the element voltage Vka (dVka / dt). ) Is too 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 voltage Vka changes abruptly after the negative polarization inversion of the emitter section 13 is completed (the time rate of change (dVka / dt) of the element voltage Vka becomes excessive). It is estimated to be.

(3) Relationship between the voltage change rate when the drive voltage Vin increases, the element voltage Vka, and the element current Ik Based on the above knowledge, the inventor does not change the drive voltage Vin in a rectangular waveform when emitting electrons. The device voltage Vka and the device current Ik when the rate of increase (voltage change rate = time change rate = dVin / dt) was varied were investigated.

  FIG. 20 is a time chart showing the results of this experiment. In FIG. 20, a line L0 indicates a drive voltage Vin that changes in a rectangular waveform as in the past, and a line M0 and a line N0 indicate the element voltage Vka and the element current Ik when the drive voltage Vin indicated by the line L0 is applied, respectively. ing. The line L1 indicates the driving voltage Vin that gradually increases at a predetermined voltage change rate α1 (= dVin / dt, that is, the slope), and the line M1 and the line N1 give the driving voltage Vin indicated by the line L1. The device voltage Vka and the device current Ik are respectively shown.

  Similarly, the line L2 indicates the drive voltage Vin that gradually increases at a predetermined voltage change rate α2, and the line M2 and the line N2 indicate the element voltage Vka and the element when the drive voltage Vin indicated by the line L2 is applied. Each current Ik is shown. The line L3 indicates the drive voltage Vin that gradually increases at a predetermined voltage change rate α3, and the line M3 and the line N3 indicate the element voltage Vka and the element current Ik when the drive voltage Vin indicated by the line L3 is applied. Each is shown. In this case, α1> α2> α3> 0.

  According to FIG. 20, it is understood that when the drive voltage Vin is increased in order to emit electrons, the peak (maximum value) of the device current Ik decreases as the voltage change rate of the drive voltage Vin decreases (broken line). (Refer to the element current Ik in the portion surrounded by the circle of). In particular, as can be understood from the lines L3, M3, and N3, when the voltage change rate of the drive voltage Vin is set so that the change of the element voltage Vka follows the change of the drive voltage Vin, the peak of the element current Ik is effective. It was confirmed to be smaller.

(4) Relationship between change rate when drive voltage Vin decreases, element voltage Vka and element current Ik Further, the inventor gradually decreases drive voltage Vin and decreases the electron voltage when accumulating electrons in emitter section 13. The device voltage Vka and the device current Ik when the speed (magnitude of time change rate) was various values were examined.

  FIG. 21 is a time chart showing the results of this experiment. In FIG. 21, a line R0 indicates a drive voltage Vin that changes in a rectangular wave shape at the time of falling as usual, and a line S0 and a line T0 indicate an element voltage Vka and an element current when the drive voltage Vin indicated by the line R0 is applied. Ik is shown respectively. The line R1 indicates the drive voltage Vin that gradually decreases at a predetermined voltage change rate β1 (= | dVin / dt |, that is, the magnitude of the slope), and the line S1 and the line T1 indicate the drive indicated by the line R1. The device voltage Vka and the device current Ik when the voltage Vin is applied are shown.

  Similarly, the line R2 indicates the drive voltage Vin that gradually decreases at a predetermined voltage change rate β2 (= | dVin / dt |), and the lines S2 and T2 give the drive voltage Vin indicated by the line R2. The device voltage Vka and the device current Ik are shown respectively. The line R3 indicates the driving voltage Vin that gradually decreases at a predetermined voltage change rate β3 (= | dVin / dt |), and the line S3 and the line T3 are obtained when the driving voltage Vin indicated by the line R3 is applied. The device voltage Vka and the device current Ik are shown respectively. In this case, β1> β2> β3> 0.

  According to FIG. 21, even when the drive voltage Vin is decreased to accumulate electrons, the peak (maximum value) of the element current Ik decreases as the voltage change rate of the drive voltage Vin decreases. It is understood (refer to the device current Ik in the part surrounded by the broken-line circle). In addition, it is understood that the rate of change of the element voltage Vka after completion of the negative polarization reversal is smaller but smaller as the magnitude of the rate of change of the drive voltage Vin is reduced (due to the one-dot chain line circle). (See the element voltage Vka in the enclosed part.)

(Control of drive voltage)
The drive voltage application circuit 21 according to the first embodiment generates a voltage that changes as shown in FIG. 22 as the drive voltage Vin based on the knowledge obtained by the above-described experiment. That is, the power supply 21s of the drive voltage applying circuit 21 starts to increase the drive voltage Vin from the first voltage Vm, which is a negative predetermined voltage, at a predetermined time (time t1 shown in FIG. 22), and starts positive polarization inversion. The drive voltage Vin reaches the second voltage Vp, which is a predetermined positive voltage, at time t4 after (time t2) and completion of positive side polarization reversal (that is, time t3 when the positive coercive field voltage is exceeded). The drive voltage Vin is gradually increased at a time change rate (voltage change rate) magnitude α (α = dVin / dt> 0).

  As a result, the inrush current (the peak value of the device current Ik) when electrons are emitted by increasing the drive voltage Vin is reduced, and a sudden change in the device voltage Vka that occurs after completion of positive side polarization inversion is avoided. . As a result, unnecessary electron emission when the driving voltage Vin is increased can be avoided.

  Further, the power supply 21s of the drive voltage application circuit 21 decreases the drive voltage Vin from the second voltage Vp, which is a positive predetermined voltage, at a predetermined time (time t5) after the electron emission is completed (time t4). The drive voltage Vin is a predetermined negative voltage at a time after the negative side polarization reversal start time (time t6) and the negative side polarization reversal completion time (that is, time t7 when the negative coercive electric field voltage is exceeded). The drive voltage Vin is gradually decreased with a time change rate magnitude β so as to reach a certain first voltage Vm.

  As a result, the inrush current (the peak value of the device current Ik) when accumulating electrons by decreasing the drive voltage Vin is reduced, and a sudden change in the device voltage Vka that occurs after completion of the negative side polarization reversal is avoided. . As a result, unnecessary electron emission when the drive voltage Vin is decreased can be avoided.

(Control of collector electrode)
The collector voltage application circuit 23 indicates that “when the drive voltage Vin is changed toward the second positive voltage Vp, which is a positive predetermined voltage, the emission of electrons through the fine through hole 14a is substantially completed ( At a predetermined time point within a period from “right after time t4 in FIG. 22)” to “a voltage decrease start point at which the drive voltage Vin starts to decrease from the second voltage Vp, which is a positive predetermined voltage” (time t5 in FIG. 22). The second collector voltage V2 is applied to the collector electrode 18 so that the collector 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 23 switches the connection destination of the fixed connection point of the switching element 23b from the switching point connected to the constant voltage source 23c to the switching point grounded at this predetermined time.

  Note that the switching element 23b may be configured to be a floating point that does not connect the grounded switching point anywhere. In this case, the switching element 23b switches the connection destination of the fixed connection point from the switching point connected to the constant voltage source 23c 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 23 reads “the time when the electron accumulation is completed when the drive voltage Vin is the first negative voltage Vm, which is a negative predetermined voltage (near time t8 in FIG. 22). At a predetermined time within a period from “time” to “before the completion of re-arrival electron emission”, the connection point of the fixed connection point of the switching element 23b is connected to the constant voltage source 23c from the grounded switching point. Switch to the selected switching point. That is, the collector voltage application circuit 23 resumes 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, which can be attributed to “a large voltage change rate of the device voltage Vka” that occurs after the negative-side polarization inversion is completed, can be avoided more reliably.

Note that the collector electrode on time can also be set as described below.
(A) The collector electrode ON time is defined as “voltage increase start time (time t10 in FIG. 22) when the drive voltage Vin starts to increase from the first voltage Vm toward the second voltage Vp”.

  Thereby, unnecessary electron emission in the electron accumulation period (time t5 to t10 in FIG. 22) can be avoided. Furthermore, since the first collector voltage is applied to the collector electrode 18 over the entire period in which the drive voltage Vin is increased to emit electrons, the normally emitted electrons can be guided to the vicinity of the collector electrode 18. it can. In addition, the time point at which the drive voltage Vin starts to increase coincides with the time point at which the first collector voltage is applied to the collector electrode, so that the circuit for performing such an operation can be simplified.

(B) The time when the collector electrode is turned on is changed from “a time immediately after the point when the drive voltage Vin increases toward the second voltage Vp to the peak of the inrush current flowing through the emitter section 13” to “the positive side polarization inversion is completed”. It is set to a predetermined time within the period up to “time”.

  Thereby, unnecessary electron emission during the electron accumulation period (time t5 to t10 in FIG. 22) and unnecessary electron emission due to a large inrush current when the drive voltage Vin is increased 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 (time t5 to t10 in FIG. 22) can be avoided. Furthermore, unnecessary electron emission due to an inrush current or the like until the drive voltage Vin is increasing and the positive polarization inversion 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. Further, 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 (time t5 to t10 in FIG. 22) can be avoided. Furthermore, unnecessary electron emission due to an inrush current or the like until the drive voltage Vin is increasing and the positive polarization inversion 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 drive voltage Vin is increasing and the actual element 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 (time t5 to t10 in FIG. 22) 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 element voltage Vka changes according to the image (the amount of electrons to be emitted), if the time when the element voltage reaches the predetermined threshold voltage Vth is the collector electrode on time, the element voltage Vka Regardless of how it changes, the collector electrode can always be turned on at an appropriate timing (a timing at which as many electrons as normally emitted are directed to the collector electrode as much as possible while suppressing unnecessary electron emission).

(Specific examples of drive voltage application circuit, focusing electrode potential application circuit, and collector voltage application circuit)
Next, specific configurations and operations of the drive voltage application circuit 21, the focusing electrode potential application circuit 22, and the collector voltage application circuit 23 will be described.

  As shown in FIG. 23, the drive voltage application circuit 21 includes a row selection circuit 21a, a pulse generation source 21b, and a signal supply circuit 21c. In FIG. 23, the ones denoted by reference signs D11, D12,... D22, D23, etc. are each the above-described one element (electron emitting element constituted by a portion where the upper electrode 14 and the lower electrode 12 overlap). Show. Further, the electron-emitting device 10 in this example includes n elements in the row direction and m elements in the column direction.

  The row selection circuit 21a is connected to the control signal line 100a of the signal control circuit 100 and the positive line 110p and the negative line 110m of the power supply circuit 110. The row selection circuit 21a is further connected to a plurality of row selection lines LL. Each row selection line LL is connected to the lower electrode 12 of a plurality of elements (elements on the same row) forming a group. For example, the row selection line LL1 is connected to the lower electrodes 12 of the elements D11, D12, D13,... D1m in the first row, and the row selection line LL2 is the lower portions of the elements D21, D22, D23,. It is connected to the electrode 12.

  In the charge accumulation period Td in which electrons are accumulated in the emitter section 13 of each element, the row selection circuit 21a responds to a control signal from the signal control circuit 100 for a certain period (row selection line LL). (Period) A selection signal Ss (here, a voltage signal of 50 V) is output only for Ts, and a non-selection signal Sn (here, a voltage signal of 0 V) is output to the remaining row selection lines LL. The row selection circuit 21a sequentially changes the row selection line LL that outputs the selection signal Ss every fixed row selection period Ts.

  The pulse generation source 21b generates a reference voltage (here, 0V) in the charge accumulation period Td, and generates a predetermined constant voltage (here, -400V) in the light emission period (lighting period, electron emission period) Th. It is like that. The pulse generation source 21b is connected between the negative electrode line 110m of the power supply circuit 110 and the ground (GND).

  The control signal line 100b of the signal control circuit 100 and the positive line 110p and the negative line 110m of the power supply circuit 110 are connected to the signal supply circuit 21c. The signal supply circuit 21c includes a pulse generation circuit 21c1 and an amplitude modulation circuit 21c2 inside.

  The pulse generation circuit 21c1 outputs a pulse signal Sp having a constant amplitude (here, 50V) at a constant pulse period in the charge accumulation period Td, and outputs a reference voltage (here, 0V) in the light emission period Th. It is like that.

  The amplitude modulation circuit 21c2 is connected to the pulse generation circuit 21c1 so as to input the pulse signal Sp from the pulse generation circuit 21c1. The amplitude modulation circuit 21c2 is connected to a plurality of pixel signal lines UL. Each of the pixel signal lines UL is connected to the upper electrode 14 of a plurality of elements (elements on the same column) forming a group. For example, the pixel signal line UL1 is connected to the upper electrodes 14 of the elements D11, D21,... Dn1 in the first column, and the pixel signal line UL2 is connected to the upper electrodes 14 of the elements D12, D22,. The pixel signal line UL3 is connected to the upper electrodes of the elements D13, D23,... Dn2 in the third column.

  The amplitude modulation circuit 21c2 modulates the amplitude of the pulse signal Sp according to the luminance level of the pixel in the selected row in the charge accumulation period Td, and the amplitude-modulated signal (here, any of 0, 30, 50V) Voltage signal) is output as a pixel signal Sd to a plurality of pixel signal lines UL (UL1, UL2,... ULm). Further, the amplitude modulation circuit 21c2 outputs the reference voltage (0V) generated by the pulse generation circuit 21c1 as it is during the light emission period Th.

  The signal control circuit 100 receives the video signal Sv and the synchronization signal Sc, and controls the signal for controlling the row selection circuit 21a, the signal for controlling the signal supply circuit 21c, and the collector voltage applying circuit 23 based on these input signals. Signals are output to the signal line 100a, the signal line 100b, and the signal line 100c, respectively.

  The power supply circuit 110 outputs a voltage signal for making the potential of the positive line 110p higher than the potential of the negative line 110m by a certain voltage (here, 50V) to the positive line 110p and the negative line 110m.

  The focusing electrode potential application circuit 22 is connected to a connection line SL that connects all the focusing electrodes 16. The focusing electrode potential applying circuit 22 applies a potential Vs (for example, −50 V) with respect to the ground to the connection line SL.

  The collector voltage application circuit 23 is connected to the connection line CL connected to the collector electrode 18 and the signal line 100 c of the signal control circuit 100. The collector voltage application circuit 23 has a positive first voltage Vc (= first collector voltage V1) and a second voltage smaller than the first voltage Vc (here, a second collector voltage V2 that is a ground potential) applied to the connection line CL. = 0 (V)) is alternately applied based on the signal from the signal control circuit 100.

  Next, the operation of the circuit thus configured will be described. First, at the start of the charge accumulation period Td that starts at a certain time, the row selection circuit 21a outputs a selection signal Ss (50V) to the row selection line LL1 of the first row based on a control signal from the signal control circuit 100. Then, the non-selection signal Sn (0 V) is output to the other row selection line LL. At this time, the row selection circuit 21a sets the magnitude (| dV / dt |) of the voltage change rate of the selection signal Ss given to the row selection line LL1 to a predetermined value (predetermined voltage change rate) β. That is, the row selection circuit 21a gradually increases from 0V to 50V at the voltage change rate magnitude β, and then applies a voltage that maintains 50V to the row selection line as the selection signal Ss. Accordingly, the potential of each lower electrode 12 of the elements D11, D12, D13,... D1m in the first row becomes the voltage (50 V) of the selection signal Ss. Further, the potentials of the lower electrodes 12 of other elements (for example, the elements D21 to D2m in the second row and the elements D31 to D3m in the third row) become the voltage (0 V) of the non-selection signal Sn.

  At this time, the signal supply circuit 21c is configured by each of the elements in the selected row (that is, the elements D11, D12, D13,... D1m in the first row) based on the control signal from the signal control circuit 100. A pixel signal Sd (here, any voltage signal of 0, 30, 50 V) corresponding to the luminance level of each pixel is output to a plurality of pixel signal lines UL (UL1, UL2,... ULm). The potential difference between the pixel signal Sd and the selection signal Ss becomes the drive voltage Vin.

  In this case, for example, assuming that the pixel signal Sd of 0 V is applied to the pixel signal line UL1, the element voltage Vka (D11) that is a potential difference between the upper electrode 14 and the lower electrode 12 of the element D11 is finally negative. Focusing is performed at −50V (= 0V−50V) which is a predetermined voltage Vm. Thereby, a very large number of electrons are accumulated in the emitter section 13 near the upper electrode 14 of the element D11. Further, assuming that the pixel signal Sd of 30 V is applied to the pixel signal line UL2, the element voltage Vka (D12) is −20 V (= 30 V−50 V) which is the negative predetermined voltage Vm described above. Thereby, fewer electrons than the element D11 are accumulated in the emitter section 13 near the upper electrode 14 of the element D12.

  The drive voltage Vin applied to these elements is a voltage at which the selection signal Ss gradually increases from 0 V to 50 V at a voltage change rate β, and thus the first voltage Vm that is the negative predetermined voltage described above. Gradually decreases toward, and then becomes a voltage that maintains the first voltage Vm.

  Furthermore, assuming that the pixel signal Sd of 50 V is applied to the pixel signal line UL3, the element voltage Vka (D13) of the element D13 is 0 V (= 50 V−50 V). Accordingly, no electrons are accumulated in the emitter section 13 of the element D13. That is, no polarization inversion occurs in the emitter section 13 of the element D13.

  Next, when a row selection period Ts (a time sufficient for accumulating electrons in the selected element, for example, a time corresponding to time t6 to time t10 shown in FIG. 22) elapses, the row selection circuit 21a Based on the control signal from the signal control circuit 100, the selection signal Ss (voltage gradually increasing from 0V to 50V with a voltage change rate β) is output to the second row selection line LL2, and the other row selection lines are output. The non-selection signal Sn (0 V) is output to Thereby, the potential of each lower electrode 12 of the elements D21, D22, D23,... D2m in the second row becomes the voltage (50 V) of the selection signal Ss. Further, the potentials of the lower electrodes 12 of other elements (for example, the elements D11 to D1m in the first row and the elements D31 to D3m in the third row) become the voltage (0 V) of the non-selection signal Sn.

  On the other hand, the signal supply circuit 21c is configured by each of the elements in the selected row (that is, the elements D21, D22, D23,... D2m in the second row) based on the control signal from the signal control circuit 100. A pixel signal Sd (a voltage signal of 0, 30, or 50 V) corresponding to the luminance level of each pixel is output to a plurality of pixel signal lines UL (UL1, UL2,... ULm). As a result, an amount of electrons corresponding to the pixel signal Sd is accumulated in the emitters of the elements D21, D22, D23,... D2m in the second row.

  The element voltage Vka of the element to which the voltage (0V) of the non-selection signal Sn is applied to the lower electrode is 0V (in this case, the upper electrode potential = 0V, the lower electrode potential = 0V), 30V (in this case, The potential of the upper electrode = 30V, the potential of the lower electrode = 0V) or 50V (in this case, the potential of the upper electrode = 50V, the potential of the lower electrode = 0V), but electrons are already accumulated at this level of voltage. No polarization inversion of the element occurs and no electrons are emitted from the element.

  Further, the drive voltage Vin for the element connected to the row selection line LL1 to which the selection signal Ss has been given immediately before the selection signal Ss starts to be output to the row selection line LL2 is a voltage between −50 to 0V. The drive voltage Vin for the element becomes 0 to 50 V when the selection signal Ss starts to be output to the row selection line LL2. Thus, when the selected element changes to a non-selected element, the drive voltage Vin applied to the element increases at a relatively large voltage change rate (magnitude) γ.

  Further, when the row selection period Ts elapses, the row selection circuit 21a applies a selection signal Ss (voltage that gradually increases from 0V to 50V at a voltage change rate β) to the third row selection line LL3 (not shown). In addition to outputting, the non-selection signal Sn (0 V) is output to the other row selection lines. In addition, the signal supply circuit 21c outputs pixel signals Sd corresponding to the luminance levels of the respective pixels configured by the selected elements in the third row to the plurality of pixel signal lines UL. Such an operation is repeated until all rows are selected every time the row selection period Ts elapses. As a result, at a predetermined point in time, electrons (amount including “0”) corresponding to the luminance level of the pixels formed by the respective elements are accumulated in the emitter sections 13 of all the elements. The above is the operation in the charge accumulation period Td.

  Next, the row selection circuit 21a generates a large negative voltage (here, + 50V generated by the power supply circuit 110 and the pulse generation source 21b) with respect to all the row selection lines LL in order to start the light emission period Th. Apply -350V, which is a difference of -400V. At this time, the row selection circuit 21a applies a voltage that gradually decreases to −350 V at the voltage change rate magnitude α to all the row selection lines LL. As a result, the potentials of the lower electrodes 12 of all the elements gradually change toward a large negative voltage (−350 V). At the same time, the signal supply circuit 21c outputs the reference voltage (0 V) generated by the pulse generation circuit 21c1 through the amplitude modulation circuit 21c2 to all the pixel signal lines UL as it is. Thereby, the potentials of the upper electrodes 14 of all the elements become the reference voltage (0 V).

  As a result, the drive voltage Vin applied to all the elements gradually changes to the second voltage Vp (= 350 V) which is a positive predetermined voltage at the magnitude α of the voltage change rate. As a result, the polarization is reversed again, and the electrons accumulated in the emitter portions 13 of the respective elements are released simultaneously by the Coulomb repulsion. As a result, the phosphor located above each element emits light, and an image is displayed. In the emitter portion of the element that has not accumulated electrons due to the voltage Vin between the upper and lower electrodes being “0” during the charge accumulation period Td, no polarization inversion has occurred. Polarization inversion does not occur even when a large positive voltage is reached. Therefore, for example, an element that does not need to emit electrons due to an image relationship at a certain timing does not consume useless power associated with polarization inversion.

  As described above, the drive voltage application circuit 21 sequentially sets the drive voltage Vin for each of the plurality of elements as the first voltage Vm, which is a negative predetermined voltage, sequentially in the charge accumulation period Td. Thereafter, when the operation of accumulating electrons for all the elements is completed, the drive voltage applying circuit 21 simultaneously sets the drive voltage Vin for all the elements as the second voltage Vp, which is a positive predetermined voltage, for all the plurality of elements. The electrons are emitted all at once and the light emission period Th is started. Further, thereafter, when a predetermined light emission period Th elapses, the drive voltage application circuit 21 starts the charge accumulation period Td again.

  By the way, the above-described magnitudes α and β of the voltage change rate are both set to values smaller than the magnitude γ of the voltage change rate. Therefore, it is possible to avoid light emission associated with unnecessary (or excessive) electron emission during the above-described electron emission, and light emission associated with unnecessary (or excessive) electron emission during the above-described electron accumulation. It can be avoided.

  When the charge accumulation period Td is restarted after the end of the light emission period Th, the driving voltage Vin for all elements is set to a voltage (first voltage) from which the accumulation of electrons does not occur in any element from the second voltage Vp. (The third voltage between Vm and the second voltage Vp) Vn is abruptly decreased at the magnitude γ of the voltage change rate, and thereafter the third voltage Vn is maintained for a predetermined time, and then the operation in the charge accumulation period Td is performed. You may start.

  Further, in this circuit example, since a predetermined potential (Vs) is applied to each focusing electrode, electrons radiated from the upper electrode 14 of each element are only in the phosphor existing above each upper electrode 14. Irradiated. As a result, a clear image is provided.

  On the other hand, the collector voltage application circuit 23 determines that the drive voltage Vin of the element in which electrons are accumulated earliest among the plurality of elements is the first voltage from “the first time point when the substantial electron emission of all elements is completed”. The collector electrode 18 is turned off at a predetermined time point within a period until “a time point at which the decrease starts toward Vm”. Thereby, the collector electrode 18 is turned off at a time point before the start of the charge accumulation period Td of all the elements.

  Further, the collector voltage applying circuit 23 is after the point in time when the element whose drive voltage Vin is changed to the first voltage Vm latest within one charge accumulation period Td has completed the accumulation of electrons, and then comes again. The collector electrode 18 is turned on at a predetermined time within a period until the substantial electron emission completion time of all devices.

  As described above, in the electron emission device 10, when one element is emitting electrons, the other element does not accumulate electrons. Therefore, the collector voltage application circuit 23 is able to perform normal operation while suppressing unnecessary electron emission only by switching the collector electrode 18 between the on state and the off state even in the electron emission device 10 having a plurality of elements. Energy can be imparted to the electrons emitted to the. As a result, the collector voltage application circuit 23 is an inexpensive and simple circuit.

<Second Embodiment>
Next, an electron emission device according to a second embodiment of the present invention will be described. The second embodiment is different from the electron emission device 10 only in that the drive voltage (voltage between upper and lower electrodes) Vin is changed so as to be different from the drive voltage Vin in the electron emission device 10 of the first embodiment. Therefore, hereinafter, this difference will be mainly described.

  The drive voltage application circuit 21 of the second embodiment includes an element voltage measurement circuit, a positive-side polarization inversion completion detection circuit, and a negative-side polarization inversion completion detection circuit (all not shown). The element voltage measurement circuit measures the element voltage Vka.

  The positive side polarization inversion completion detection circuit monitors the waveform of the element voltage Vka measured by the element voltage measurement circuit, and when the element voltage Vka becomes a voltage in the vicinity of the positive coercive electric field voltage, the time of the element voltage Vka is measured. The rate of change (dVka / dt) becomes smaller than a predetermined value, and thereafter, the time change rate (dVka / dt) of the element voltage starts to increase rapidly (the rate of change over time exceeds the predetermined rate of change). It is detected as the time of completion of polarization reversal.

  Similarly, the negative side polarization inversion completion detection circuit monitors the waveform of the element voltage Vka measured by the element voltage measurement circuit, and when the element voltage Vka becomes a voltage near the negative coercive field voltage, The absolute value of the time change rate (dVka / dt) of Vka becomes smaller than a predetermined value, and thereafter the absolute value of the time change rate (dVka / dt) of the element voltage starts to increase rapidly (the absolute value of the time change rate is absolute). The time point when the value exceeds a predetermined positive value) is detected as the time point when the negative polarization inversion is completed.

  The drive voltage application circuit 21 (power supply 21s) reaches the positive voltage arrival time (time t4) when the drive voltage Vin reaches the second voltage Vp, which is a positive predetermined voltage, from the voltage increase start time (time t1) shown in FIG. In the period up to (voltage increase period), the drive voltage Vin is gradually increased from the first negative voltage Vm. At this time, the power source 21s generates a voltage that gradually increases at the voltage change rate (slope) αS1 from the voltage increase start time (time t1) as the drive voltage Vin. When the positive side polarization reversal completion detection circuit detects the time when the positive side polarization reversal is completed (time t3), the power supply 21s is supplied to the second voltage Vp until the positive voltage is reached (time t4). A voltage that gradually increases at a voltage increase rate αL1 larger than the increase rate αS1 is generated as the drive voltage Vin.

  As a result, during the voltage increase period (time t1 to t4) of the drive voltage Vin, the drive voltage Vin increases most slowly during the period from the voltage increase start time (time t1) to the positive side polarization reversal completion time (time t3). I'm damned.

  During the period from the voltage increase start time (time t1) of the drive voltage Vin to the positive side polarization reversal completion time (time t3) at which the polarization inversion of the emitter section 13 is substantially completed, an inrush current accompanying the change of the drive voltage Vin Is the largest period. Therefore, as in this embodiment, if the drive voltage Vin is increased most gently during the period from the voltage increase start time (time t1) to the time when the positive-side polarization inversion ends (time t3), the emitter section Thus, the magnitude of the inrush current flowing through 13 can be effectively reduced. As a result, unnecessary emission of electrons due to the inrush current can be avoided. Further, since the drive voltage Vin can be gradually increased at a relatively large voltage change rate αL1 from the positive side polarization reversal completion time (time t3) to the positive voltage arrival time (time t4), the voltage increase period (electron emission) It is also possible to shorten the total time of the period for performing the operation.

  Further, the drive voltage application circuit 21 (power supply 21s) reaches the negative voltage arrival time (time) when the drive voltage Vin reaches the first negative voltage Vm, which is a predetermined negative voltage, from the voltage decrease start time (time t5) shown in FIG. During the period up to t8) (voltage decrease period), a voltage that gradually decreases from the second voltage Vp, which is a positive predetermined voltage, is generated as the drive voltage Vin. At this time, the power source 21s generates a voltage that gradually decreases from the voltage decrease start time (time t5) at the voltage change rate (gradient) βS1 (βS1> 0) as the drive voltage Vin. Furthermore, when the negative side polarization reversal completion detection circuit detects the time point when the negative side polarization reversal is completed (time t7), the power source 21s is moved toward the first voltage Vm until the negative voltage arrival time point (time t8). A voltage that gradually decreases at a voltage increase rate magnitude βL1 (βL1> 0) larger than the increase rate magnitude βS1 is generated as the drive voltage Vin.

  As a result, during the voltage decrease period (time t5 to t8) of the drive voltage Vin, the drive voltage Vin decreases most slowly during the period from the voltage decrease start time (time t5) to the negative side polarization reversal completion time (time t7). I'm damned.

  During the period from the voltage decrease start time (time t5) of the drive voltage Vin to the negative polarization inversion completion time (time t7) at which the polarization inversion of the emitter section 13 is substantially completed, an inrush current accompanying the change of the drive voltage Vin Is the largest period. Therefore, as in this embodiment, if the drive voltage Vin is decreased most slowly during the period from the voltage decrease start time (time t5) to the negative side polarization reversal completion time (time t7), the current flows to the emitter section 13. The magnitude of the inrush current can be effectively reduced. As a result, unnecessary emission of electrons due to the inrush current can be avoided. Further, since the drive voltage Vin can be gradually decreased at a relatively large voltage change rate βL1 from the negative side polarization reversal completion time (time t7) to the negative voltage arrival time (time t8), the voltage decrease period The total time of (a period for performing the operation of storing electrons) can be shortened.

<Third Embodiment>
Next, an electron emission device according to a third embodiment of the present invention will be described. The third embodiment is different from the method of changing the driving voltage Vin in the electron emission device of the second embodiment only in the way of changing the driving voltage (voltage between the upper and lower electrodes) Vin. Different from the discharge device. Therefore, hereinafter, this difference will be mainly described.

  In the third embodiment, the power supply 21s of the drive voltage application circuit 21 generates the voltage shown in FIG. 25, and the drive voltage application circuit 21 applies this voltage between the upper electrode 14 and the lower electrode 12 as the drive voltage Vin. It is supposed to be.

  More specifically, the drive voltage applying circuit 21 (power supply 21s) is a positive voltage at which the drive voltage Vin reaches the second voltage Vp that is a predetermined positive voltage from the voltage increase start time (time t1) shown in FIG. In the period up to the arrival time (time t4) (voltage increase period), the drive voltage Vin is gradually increased from the first voltage Vm which is a negative predetermined voltage. At this time, the power source 21s generates a voltage that gradually increases at the voltage change rate (slope) αL2 from the voltage increase start time (time t1) as the drive voltage Vin. When the positive side polarization reversal completion detection circuit detects the time when the positive side polarization reversal is completed (time t3), the power supply 21s is supplied to the second voltage Vp until the positive voltage is reached (time t4). A voltage that gradually increases at a voltage increase rate αS2 smaller than the increase rate αL2 is generated as the drive voltage Vin.

  As a result, during the voltage increase period (time t1 to t4) of the drive voltage Vin, the drive voltage Vin increases most slowly during the period from the positive side polarization inversion completion time (time t3) to the positive voltage arrival time (time t4). It is done.

  Depending on the element itself (or an element for which other countermeasures have been taken), rushing occurs when unnecessary electron emission due to a sudden change in the element voltage Vka after completion of positive side polarization inversion starts to increase the voltage Vin between the upper and lower electrodes. It may occur more frequently than unwanted electron emission due to current. Therefore, as in this embodiment, unnecessary electron emission is achieved by increasing the voltage Vin between the upper and lower electrodes most slowly during the period from the positive side polarization inversion completion time (time t3) to the positive voltage arrival time (time t4). Can be effectively avoided. Further, since the drive voltage Vin can be gradually increased at a relatively large voltage change rate αL2 from the voltage increase start time (time t1) to the positive side polarization reversal completion time (time t3), the voltage increase period (electron emission) It is also possible to shorten the total time of the period for performing the operation.

  Further, the drive voltage application circuit 21 (power supply 21s) reaches the negative voltage arrival time (time) when the drive voltage Vin reaches the first negative voltage Vm, which is a negative negative voltage, from the voltage decrease start time (time t5) shown in FIG. During the period up to t8) (voltage decrease period), a voltage that gradually decreases from the second voltage Vp, which is a positive predetermined voltage, is generated as the drive voltage Vin. At this time, the power source 21s generates a voltage that gradually decreases at the voltage change rate (slope) magnitude βL2 (βL2> 0) from the voltage decrease start time (time t5) as the drive voltage Vin. Furthermore, when the negative side polarization reversal completion detection circuit detects the time point when the negative side polarization reversal is completed (time t7), the power source 21s is moved toward the first voltage Vm until the negative voltage arrival time point (time t8). A voltage that gradually decreases at a voltage increase rate magnitude βS2 (βS2> 0) smaller than the increase rate magnitude βL2 is generated as the drive voltage Vin.

  As a result, during the voltage decrease period (time t5 to t8) of the drive voltage Vin, the drive voltage Vin decreases most slowly during the period from the negative side polarization inversion completion time (time t7) to the negative voltage arrival time (time t8). I'm damned.

  Depending on the element itself (or an element for which other countermeasures have been taken), unnecessary electron emission due to a sudden change in the element voltage Vka after completion of negative side polarization reversal is caused by an inrush current when the voltage Vin between the upper and lower electrodes decreases. May occur more frequently than unnecessary electron emission. Therefore, as described above, unnecessary electron emission is effectively reduced by decreasing the drive voltage Vin most slowly during the period from the time when the negative side polarization reversal is completed (time t7) to the time when the negative voltage is reached (time t8). It can be avoided. Further, since the drive voltage Vin can be gradually decreased at a relatively large voltage change rate βL2 from the voltage decrease start time (time t5) to the negative side polarization reversal completion time (time t7), the voltage decrease period The total length of (a period for performing the operation of storing electrons) can be shortened.

<Fourth embodiment>
Next, an electron emission apparatus according to the fourth embodiment of the present invention will be described. The fourth embodiment is different from the electron emission device 10 only in that the drive voltage Vin is changed to be different from the drive voltage Vin in the electron emission device 10 of the first embodiment. Therefore, hereinafter, this difference will be mainly described.

  In the fourth embodiment, the power supply 21s of the drive voltage application circuit 21 generates the voltage shown in FIG. 26, and the drive voltage application circuit 21 applies this voltage between the upper electrode 14 and the lower electrode 12 as the drive voltage Vin. It is supposed to do.

  More specifically, the drive voltage application circuit 21 (power supply 21s) has a large voltage change rate (slope) k1 from the second voltage Vp to the third voltage Vn at the time of sudden voltage decrease (time t1) shown in FIG. A voltage that suddenly decreases is generated as the drive voltage Vin. Next, the power supply 21s maintains the third voltage Vn until the voltage decrease start time (time t2), which is the time when a predetermined time has elapsed from the voltage sudden decrease time (time t1).

  The third voltage Vn is an intermediate voltage between the first voltage Vm, which is the negative predetermined voltage, and the second voltage Vp, which is the positive predetermined voltage, and the element voltage Vka is changed to the third voltage Vn. When the values match, the voltage is such that no electrons are accumulated in the emitter section 13 (or no additional electrons are accumulated) and no electrons are emitted from the emitter section 13.

  Thereafter, the power source 21s generates, as the drive voltage Vin, a voltage that decreases at the voltage change rate magnitude k2 from the third voltage Vn at the voltage decrease start time (time t2). Further, when another predetermined time set in advance from the voltage decrease start time (time t2) has elapsed and the time t3 is considered to be the negative side polarization reversal completion time, the power supply 21s has the drive voltage Vin of the first voltage Vm. Until the negative voltage reaching point (time t4) that reaches the voltage, a voltage that decreases from the drive voltage Vin at the time t3 at the voltage change rate magnitude k3 is generated as the drive voltage Vin.

  Next, the power source 21s maintains the first voltage Vm as the drive voltage Vin until another predetermined time elapses from the time when the negative voltage is reached (time t4) until the time when the voltage suddenly increases (time t5). At the time of rapid increase (time t5), a voltage that rapidly increases from the first voltage Vm to the third voltage Vn with a voltage change rate (slope) k4 is generated as the drive voltage Vin. Thereafter, the power source 21s maintains the third voltage Vn until a voltage increase start time (time t6), which is a time when another predetermined time has elapsed from the voltage sudden increase time (time t5).

  Next, the power source 21s generates a voltage that increases from the third voltage Vn at the voltage change rate magnitude k5 as the drive voltage Vin at the voltage increase start time (time t6). Furthermore, when another predetermined time set in advance from the voltage increase start time (time t6) passes and time t7 is considered to be the positive side polarization reversal completion time, the power supply 21s has the drive voltage Vin equal to the second voltage Vp. Until the positive voltage reaching time point (time t8), the voltage increasing at the voltage change rate magnitude k6 from the driving voltage Vin at time t7 is generated as the driving voltage Vin. Thereafter, the power source 21s repeatedly generates voltages at times t1 to t8.

  In this embodiment, k3 <k2 <k1. That is, the power supply 21 s generates the second voltage Vp, and then does not accumulate the element voltage Vka in the emitter section 13 and does not emit electrons from the emitter section 13 and the negative predetermined voltage and the positive voltage. A voltage that decreases from the second voltage Vp toward the third voltage Vn is generated at a time t1 so as to be an intermediate voltage between the predetermined voltage and then the first voltage from the third voltage Vn is generated at a time t2 to t4. The voltage Vm is configured to generate a voltage that decreases more slowly than when it decreases from the second voltage Vp to the third voltage Vn (time t1). According to experiments, unnecessary electron emission does not occur even when the drive voltage Vin changes rapidly from the second voltage Vp to the third voltage Vn. Furthermore, according to this embodiment, the drive voltage Vin that gradually changes from the third voltage Vn to the first voltage Vm is applied to the element. Therefore, it is possible to reduce the time required for electron accumulation after electron emission while avoiding unnecessary electron emission.

  In this embodiment, k6 <k5 <k4. That is, after generating the first voltage Vm, the power source 21s does not cause the device voltage Vka to further accumulate electrons in the emitter section 13 and does not cause the emitter section 13 to emit electrons. A voltage that increases from the first voltage Vm toward the third voltage Vn is generated so as to be an intermediate voltage between the positive predetermined voltage, and then the first voltage from the third voltage Vn toward the second voltage Vp is generated. A voltage that increases more slowly than when the voltage Vm increases to the third voltage Vn (time t6) is generated. According to experiments, unnecessary electron emission does not occur even when the drive voltage Vin changes rapidly from the first voltage Vm to the third voltage Vn. Furthermore, according to this embodiment, the drive voltage Vin that gently changes from the third voltage Vn to the second voltage Vp is applied to the element. Accordingly, it is possible to shorten the time required for electron emission after the accumulation of electrons while avoiding unnecessary electron emission.

  Note that k2 ≦ k3 <k1 may be satisfied, and k5 ≦ k6 <k4 may be satisfied. That is, the magnitude relationship between k2 and k3 can be determined as appropriate, and the magnitude relationship between k5 and k6 can be determined as appropriate depending on the characteristics of the element (when unnecessary emission is performed).

  Similarly to the above-described embodiment, the device voltage Vka is monitored, and the time when the device voltage Vka falls below the voltage corresponding to the negative coercive electric field voltage is detected as the negative side polarization completion time t3. The time when the voltage Vka exceeds the voltage corresponding to the positive coercive electric field voltage may be detected as the positive side polarization completion time point t7, and the change rate of the drive voltage Vin may be switched as described above at each time point.

<Fifth Embodiment>
Next, an electron emission device according to a fifth embodiment of the invention will be described. The fifth embodiment differs from the electron emission device of the fourth embodiment only in that the drive voltage Vin in the electron emission device of the fourth embodiment is changed stepwise. Therefore, hereinafter, this difference will be mainly described.

  The electron-emitting device 30 according to the fifth embodiment includes an element D and a drive voltage applying circuit 31 as shown in FIG. The element D is an element similar to the element of the first embodiment, and the transparent plate 17, the collector electrode 18, and the phosphor 19 are omitted in the drawing. The lower electrode 12 of the element D is grounded.

  The drive voltage application circuit 31 includes a voltage control circuit 32, a switching circuit 33, a plurality of resistors 34a to 34g, and a plurality of constant voltage sources 35a to 35g.

  The voltage control circuit 32 is connected to the lower electrode 12, the upper electrode 14, and the switching circuit 33 of the element D. The voltage control circuit 32 measures the element voltage Vka and sends a switching signal to the switching circuit 33 based on the measured element voltage ka.

  The switching circuit 33 includes one fixed connection point ks connected to the upper electrode 14 of the element D and a plurality (here, seven) of voltage application connection points 33a to 33g. The switching circuit 33 selects one of the plurality of voltage applying connection points 33a to 33g in response to the switching signal from the voltage control circuit 32, and connects the selected voltage applying connection point and the fixed connection point ks. It is supposed to be.

  The voltage applying connection point 33a is connected to one end of the resistor 34a. One end of the resistor 34a is connected to the cathode of a constant voltage source 35a that generates a voltage | Vm | (a voltage having the same magnitude as the first voltage Vm). The anode of the constant voltage source 35a is grounded. The voltage applying connection point 33b is connected to one end of the resistor 34b. One end of the resistor 34b is connected to the cathode of a constant voltage source 35b that generates a voltage | V1 |. The anode of the constant voltage source 35b is grounded. The voltage applying connection point 33c is connected to one end of the resistor 34c. One end of the resistor 34c is connected to the cathode of a constant voltage source 35c that generates a voltage | V2 |. The anode of the constant voltage source 35c is grounded. Here, | V1 | <| V2 | <| Vm |.

  The voltage applying connection point 33d is connected to one end of the resistor 34d. One end of the resistor 34d is connected to the anode of a constant voltage source 35d that generates the third voltage Vn. The cathode of the constant voltage source 35d is grounded. The voltage applying connection point 33e is connected to one end of the resistor 34e. One end of the resistor 34e is connected to the anode of a constant voltage source 35e that generates the voltage V3. The cathode of the constant voltage source 35e is grounded. The voltage applying connection point 33f is connected to one end of the resistor 34f. One end of the resistor 34f is connected to the anode of a constant voltage source 35f that generates the voltage V4. The cathode of the constant voltage source 35f is grounded. The voltage applying connection point 33g is connected to one end of the resistor 34g. One end of the resistor 34g is connected to the anode of a constant voltage source 35g that generates the second voltage Vp. The cathode of the constant voltage source 35g is grounded. Here, 0 <Vn <V3 <V4 <Vp.

  Next, the operation of the drive voltage applying circuit 31 configured as described above will be described with reference to FIG. Now, it is assumed that the switching circuit 33 connects the fixed connection point ks to the voltage applying connection point 33g and the second voltage Vp (Vp> 0) is applied to the element D before the predetermined time t1. At this time, at time t1, the voltage control circuit 32 sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 connects the fixed connection point ks to the voltage application connection point 33d. As a result, the drive voltage application circuit 31 generates the third voltage Vn as the drive voltage Vin. That is, the drive voltage Vin decreases from the second voltage Vp to the third voltage Vn with a relatively large voltage change rate at time t1.

  When a predetermined time elapses from time t1 and time t2 is reached, the voltage control circuit 32 sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 sets the fixed connection point ks to the voltage application connection point. 33b. As a result, the drive voltage application circuit 31 generates the voltage V1 (V1 <0) as the drive voltage Vin. Thereafter, the voltage control circuit 32 monitors the element voltage Vka, and when the element voltage Vka falls below the negative side coercive field voltage, determines that the negative side polarization reversal has been completed and sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 connects the fixed connection point ks to the voltage application connection point 33c. As a result, the drive voltage applying circuit 31 generates the voltage V2 (V2 <0) as the drive voltage Vin at time t3.

  When a predetermined time elapses from time t3 and time t4 is reached, the voltage control circuit 32 sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 sets the fixed connection point ks to the voltage application connection point. Connect to 33a. As a result, the drive voltage application circuit 31 generates the first voltage Vm (Vm <0) as the drive voltage Vin. Thereafter, the drive voltage application circuit 31 continues to generate the first voltage Vm as the drive voltage Vin until a predetermined time elapses from time t4 until time t5 is reached. As a result, the element voltage Vka reaches a negative predetermined voltage in the period from time t2 to time t5. That is, accumulation of electrons in the emitter section 13 is completed during this period.

  At time t5, the voltage control circuit 32 sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 connects the fixed connection point ks to the voltage application connection point 33d. As a result, the drive voltage application circuit 31 generates the third voltage Vn (Vn> 0) as the drive voltage Vin. That is, the drive voltage Vin increases from the first voltage Vm to the third voltage Vn at a relatively large voltage change rate at time t5.

  When a predetermined time elapses from time t5 and time t6 is reached, the voltage control circuit 32 sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 sets the fixed connection point ks to the voltage application connection point. Connect to 33e. As a result, the drive voltage application circuit 31 generates the voltage V3 (V3> 0) as the drive voltage Vin. Thereafter, the voltage control circuit 32 monitors the element voltage Vka, and when the element voltage Vka exceeds the positive coercive electric field voltage, determines that the positive-side polarization inversion has been completed and sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 connects the fixed connection point ks to the voltage application connection point 33f. As a result, the drive voltage applying circuit 31 generates the voltage V4 (V4> 0) as the drive voltage Vin at time t7.

  When a predetermined time elapses from time t7 and time t8 is reached, the voltage control circuit 32 sends a switching signal to the switching circuit 33. In response to this signal, the switching circuit 33 sets the fixed connection point ks to the voltage application connection point. Connect to 33g. As a result, the drive voltage application circuit 31 again generates the second voltage Vp as the drive voltage Vin. Thereafter, the drive voltage application circuit 31 repeatedly generates voltages at times t1 to t8.

  In the fifth embodiment, it can be considered that the constant voltage sources 35a to 35g and the switching circuit 33 together constitute one power source. Accordingly, the power supply of the fifth embodiment, like the power supply 21s of the fourth embodiment, generates the second voltage Vp, and then does not accumulate the element voltage Vka in the emitter section 13 and does not accumulate electrons from the emitter section 13. At time t1, a voltage that decreases from the second voltage Vp toward the third voltage Vn is generated so as to be an intermediate voltage between the negative predetermined voltage and the positive predetermined voltage that is not released, and thereafter The power supply gradually decreases from the third voltage Vn to the first voltage Vm at time t2 to t4, and gradually decreases from the second voltage Vp to the third voltage Vn (time t1). The voltage decreases to the first voltage Vm). Further, the drive voltage Vin is gradually decreased even after the negative side polarization reversal. Therefore, similarly to the fourth embodiment, the electron emission device 30 of the fifth embodiment can reduce the time required from the time of electron emission to the time of electron accumulation while avoiding unnecessary electron emission during electron accumulation.

  Further, the power supply of this embodiment, like the power supply 21s of the fourth embodiment, generates the first voltage Vm, and then does not accumulate the element voltage Vka in the emitter section 13 and the electrons from the emitter section 13 do not accumulate further. Generating a voltage that increases from the first voltage Vm toward the third voltage Vn so as to be an intermediate voltage between the negative predetermined voltage and the positive predetermined voltage that does not cause the At time t6 to t8, the voltage gradually increases from the third voltage Vn toward the second voltage Vp when increasing from the first voltage Vm to the third voltage Vn (time t5). The voltage increases up to Vp). Further, the drive voltage Vin is gradually increased even after the positive side polarization reversal. Therefore, the electron emission device 30 according to the fifth embodiment can shorten the time required for electron emission after electron accumulation while avoiding unnecessary electron emission during electron emission.

  In addition, a power supply that generates a drive voltage Vin for avoiding unnecessary electron emission can be provided by such a simple configuration of switching the constant voltage source connected with the switching circuit 33. In addition, if the drive voltage application circuit 31 is configured in this manner, the number of elements that should emit electrons (number of electron-emitting elements) in the electron-emitting device including a plurality of elements changes due to the characteristics of the elements. Provides a power source that can generate the appropriate drive voltage Vin with a simple configuration even when the magnitude of the drive voltage Vin appropriate for the electron emission and electron accumulation operations changes. Is done. Further, the device voltage Vka is monitored, and the drive voltage Vin is switched when the device voltage Vka falls below the negative coercive field voltage or exceeds the positive coercive field voltage. Even when the number of electron emission changes and the method of changing the device voltage Vka changes, it is possible to apply an appropriate drive voltage Vin (at an appropriate timing and in an appropriate magnitude) to the device.

  Each of the plurality of resistors 34a to 34g may have the same value or different values. Advantages brought about by appropriately setting the values of the plurality of resistors 34a to 34g (changing circuit constants) will be described in a seventh embodiment described later. Further, in the above embodiment, seven constant voltage sources are provided. However, a larger number of sets of constant voltage sources and resistors are provided, and the drive voltage Vin is generated in a step shape having a smaller step. Also good.

<Sixth Embodiment>
Next, an electron emission device according to a sixth embodiment of the present invention will be described. The sixth embodiment is different from the electron emission device 10 only in that the drive voltage (voltage between upper and lower electrodes) Vin is changed to be different from the drive voltage Vin in the electron emission device 10 of the first embodiment. Therefore, hereinafter, this difference will be mainly described.

  The drive voltage application circuit of the sixth embodiment incorporates an element voltage measurement circuit and a negative side polarization inversion completion detection circuit (both not shown) included in the drive voltage application circuit 21 of the second embodiment.

  As shown in FIG. 29, the drive voltage application circuit (power supply) reaches the positive predetermined voltage Vp from the voltage increase start time (time t1) as in the drive voltage application circuit 21 of the first embodiment. A voltage that gradually increases the drive voltage Vin from the first voltage Vm, which is a negative predetermined voltage, to the second voltage Vp, which is a positive predetermined voltage, in a period (voltage increase period) until the positive voltage reaches (time t2). appear. Further, the drive voltage applying circuit supplies the drive voltage Vin in a period (voltage decrease period) from the voltage decrease start time (time t3) to the negative voltage arrival time (time t4) when the drive voltage Vin reaches the first voltage Vm. A voltage that gradually decreases from the second voltage Vp to the first voltage Vm is generated. The drive voltage Vin to be reached when the negative voltage is reached (time t4) is also referred to as “fourth voltage” for convenience. )

  In addition, when the negative-side polarization inversion completion detection circuit detects a time point (time t5) when the negative-side polarization inversion is completed after time t4, the drive voltage applying circuit sets the magnitude of the drive voltage Vin to the first voltage ( The fourth voltage) suddenly increases from the first voltage Vm to the fifth voltage having a magnitude smaller than Vm (increases with the voltage change rate magnitude α), and then the magnitude is larger than the magnitude of the fifth voltage. A voltage that gradually decreases toward the first voltage Vm, which is a large negative voltage (decreases at a voltage change rate magnitude β smaller than the voltage change rate magnitude α), is generated. That is, when the negative polarization inversion of the emitter 13 is substantially completed, the drive voltage Vin is once brought close to the element voltage Vka at that time (the drive voltage Vin is in the vicinity of the negative coercive field voltage). Value). Thereafter, the drive voltage application circuit 21 gradually decreases the drive voltage Vin toward the first voltage Vm so that the drive voltage Vin becomes the first voltage Vm again at time t6 after a predetermined time. In this case (the time t5 to t6), the voltage change rate is smaller than the voltage change rate at the time t3 to t4 or the time t5. Further, the drive voltage applying circuit 21 generates a voltage that increases the drive voltage Vin again at time t7 after time t6. Thereafter, the drive voltage application circuit repeatedly generates voltages at times t1 to t7.

  According to the experiment, the element voltage Vka changes very steeply after the negative side polarization reversal is completed, and unnecessary electron emission is frequently performed. Therefore, if the voltage generated by the power supply is changed as in the sixth embodiment, the change in the element voltage Vka after the completion of the negative side polarization inversion becomes slow, so that unnecessary electron emission is effectively avoided. be able to. Further, since the power supply generates the first voltage Vm during the period until the negative side polarization inversion is completed, the time from the voltage decrease start time (time t3) to the negative side polarization inversion completion time (time t5) is further increased. Can be shortened.

  Note that the change in the drive voltage Vin after the completion of negative side polarization reversal (time t5 to t6) in this embodiment is accumulated in the emitter section 13 by changing the drive voltage Vin to the second voltage Vp at time t1 to t3. The emitted electrons are emitted from the emitter section, and thereafter, a voltage that gradually decreases toward the first voltage Vm is generated so that the element voltage Vka becomes a predetermined negative voltage. It can be said that the operation is supplying electrons.

  Moreover, in the said embodiment, although the 4th voltage which reaches | attains at the said negative voltage arrival time (time t4) is set to the 1st voltage Vm, it is not limited to this voltage. That is, the voltage to be reached when the negative voltage is reached (time t4) may be “the fourth voltage that is a negative voltage that can cause negative polarization reversal in the emitter portion”.

  In addition, in the above embodiment, the power supply changes from the fourth voltage to the fifth voltage at the time of completion of negative side polarization reversal (time t5), and then generates a voltage that gradually changes toward the first voltage. However, it changes from the fourth voltage to the fifth voltage at a time before the negative side polarization inversion completion time (time t5) after the negative voltage arrival time (time t4), and then toward the first voltage. A gradually changing voltage may be generated.

  In addition, in the above embodiment, the power supply generates a constant fourth voltage (first voltage Vm) from the time when the negative voltage is reached (time t4) to the time when the negative-side polarization inversion is completed (time t5). A voltage that changes within a negative voltage range that is larger than the magnitude of the fifth voltage (for example, a voltage that gradually changes from the fourth voltage toward the fifth voltage) may be generated.

  Further, in the above embodiment, the power supply generates a voltage that gradually decreases toward the fourth voltage (first voltage) Vm from the voltage decrease start time (time t3) to the negative voltage arrival time (time t4). However, a voltage that immediately changes to the fourth voltage may be generated at the voltage decrease start time (time t3).

<Seventh embodiment>
Next, an electron emission device according to a seventh embodiment of the present invention will be described. The seventh embodiment is different from the electron emission device of the second embodiment described with reference to FIG. 24 only in that the circuit constant of the circuit for connecting the power source 21s and the element is changed. Therefore, hereinafter, this difference will be mainly described.

  As shown in FIG. 30, the electron emission device 40 according to the seventh embodiment includes the above-described element D including the lower electrode 12, the emitter section 13, and the upper electrode 14, and a drive voltage application circuit 41. The element D is an element similar to the element of the first embodiment, and the transparent plate 17, the collector electrode 18, and the phosphor 19 are omitted in the drawing. The drive voltage application circuit 41 includes the drive voltage application circuit 21 described above and includes a circuit constant switching circuit (circuit constant switching means) 42.

  The circuit constant switching circuit 42 is interposed in series in a circuit for connecting the power source 21 s built in the drive voltage applying circuit 21 and the element D. The circuit constant switching circuit 42 includes a switching element 42a and a plurality of circuit elements (circuit constant setting elements) 42b1, 42b2, 42b3, and 42b4.

  The switching element 42a receives a control signal from the drive voltage application circuit 21, and the fixed connection point connected to the upper electrode 14 of the element D is connected to any of the connection points connected to the circuit elements 42b1, 42b2, 42b3, and 42b4, respectively. By selectively connecting them, any one of the circuit elements 42b1, 42b2, 42b3 and 42b4 is inserted and inserted in series in the circuit. The circuit elements 42b1, 42b2, 42b3, and 42b4 are resistors having different resistance values.

  Next, the operation of the electron emission device 40 configured as described above will be described. As described above, the electron emission device 40 changes the drive voltage Vin similarly to the electron emission device according to the second embodiment.

  Further, as shown in FIG. 31, the electron emission device 40 completes the emission at the time immediately after the time point when the emission of electrons arriving at or after the positive voltage arrival time (time t4) is substantially completed. In a period TA1 from the later time point (time tx1) to the negative side polarization reversal completion time point (time t7), the circuit element 42b1 is inserted into the circuit by the switching element 42a.

  Next, the electron emission device 40 is at a time point immediately after the time point when the accumulation of electrons arriving at or after the negative voltage arrival time point (time t8) from the time point when the negative side polarization reversal is completed (time point t8) is substantially completed. In a period TA2 up to the time after completion of certain electron accumulation (time ty2), the circuit element 42b2 is inserted into the circuit by the switching element 42a.

  Next, the electron emission device 40 has completed the positive-side polarization reversal completion time (time t3) from the time after completion of the electron accumulation (time ty2, but the waveform of the drive voltage Vin is repeated so that the time ty1 in FIG. 31). In the period TA3 until the circuit element 42b3 is inserted into the circuit by the switching element 42a.

  Further, the electron-emitting device 40 inserts the circuit element 42b4 into the circuit by the switching element 42a in the period TA4 from the time when the positive side polarization reversal is completed (time t3) to the time after the completion of emission (time tx1). The electron emission device 40 repeatedly selects and inserts such circuit elements.

This
Negative inversion of the polarization of the emitter section 13 is substantially completed during the decrease of the voltage from the voltage decrease start time (time t5) at which generation of the voltage (drive voltage Vin) decreasing toward the first voltage Vm starts. A circuit element to be inserted into the circuit in the first period TB1 until the side polarization reversal completion time (time t7);
A circuit element inserted into the circuit in the second period TB2 from the time when the negative side polarization reversal is completed (time t7) to the time when the electron is completely accumulated in the emitter 13 (time t8 to time ty2) When,
The positive side polarization reversal completion time point at which the reversal of polarization of the emitter section 13 is substantially completed during the increase of the voltage from the voltage increase start time point (time t1) at which the generation of the voltage increasing toward the second voltage Vp starts. A circuit element inserted into the circuit in the third period TB3 until (time t3);
Inserted into the circuit in the fourth period TB4 from the time when the positive side polarization reversal is completed (time t3) to the time when electron emission from the emitter 13 is substantially completed (time t4 to time tx1). Circuit elements to be
Of these, at least two circuit elements (in this example, all four circuit elements) are different circuit elements.

  That is, in this embodiment, the circuit constants in the period in which unnecessary electron emission occurs frequently depending on the characteristics of the emitter section 13 of the element D and the circuit constants in other periods are different from each other. A circuit element (for example, a resistor) to be inserted into the circuit is selected. As a result, the time from the start of electron accumulation to the completion of electron emission can be shortened while avoiding unnecessary electron emission, compared with the case where the circuit constant is not changed.

  In the above embodiment, the drive voltage Vin is gradually changed. However, as shown in FIGS. 26 and 28, when the first voltage Vm is changed to the second voltage Vp or vice versa, the drive voltage Vin is changed for a predetermined time. A voltage that maintains the third voltage Vn may be used as the drive voltage Vin. In addition, as shown in FIG. 41, the drive voltage Vin may be a voltage that changes in a rectangular wave shape.

  Furthermore, in the above embodiment, the circuit elements 42b1, 42b2, 42b3, and 42b4 are resistors having different resistance values. However, if at least two of these circuit elements have different resistance values, Good. Furthermore, the circuit element may include a coil and a capacitor in addition to the resistor. In that case, at least two of the circuit elements 42b1, 42b2, 42b3, and 42b4 may have different impedances Z.

<Eighth Embodiment>
Next, an electron emission device 50 according to an eighth embodiment of the present invention will be described with reference to FIG. The electron emission device 50 is different from the electron emission device 10 only in that the collector electrode 18 and the phosphor 19 of the electron emission device 10 are replaced with the collector electrode 18 ′ and the phosphor 19 ′. Therefore, hereinafter, this difference will be mainly described.

  In the electron emission device 50, 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 '. 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. The electron emission device 50 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 each of the electron emission devices and manufacturing method examples 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 is formed by various thick film forming methods such as screen printing, dipping, coating, electrophoresis, aerosol deposition, ion beam, sputtering, vacuum deposition, ion plating, chemical It can be formed by various thin film forming methods such as 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 the present invention appropriately controls the voltage (drive voltage) generated by the power source and the circuit constant for applying the drive voltage. It can be avoided.

  Further, by gradually increasing the voltage (drive voltage Vin) generated by the power source as described above or increasing it stepwise, the polarization inversion is performed in a state where the difference between the drive voltage Vin and the element voltage Vka is small. And electron emission occurs. Therefore, the power consumption (Joule heat) in the element, the resistance component near the element, and the circuit resistance is reduced. As a result, since the element is not heated, it can be avoided that the characteristics of the emitter section are changed by heating. Furthermore, since the element temperature does not increase, gasification of a substance adsorbed on the element can be avoided. As a result, generation of plasma is avoided, so that excessive emission of electrons (generation of large light emission) and damage to the element due to ion bombardment can be avoided.

  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. 33, 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. 34, 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. 35 and 36, another electron emission device 60 according to the present invention has a completely independent device comprising a lower electrode 62, an emitter portion 63 and an upper electrode 64 arranged on the substrate 11. And a structure in which each element is filled with an insulator 65, and a focusing electrode 66 is formed between the upper electrodes 64 of the elements adjacent to each other in the X-axis direction on the upper surface of the insulator 65. It may be.

  The electron emission device 60 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 64 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 (66) 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.

  The substrate 11 may be made of a material mainly composed of aluminum oxide or a material mainly composed of a mixture of aluminum oxide and zirconium oxide.

  By the way, as a result of conducting various experiments on such an electron emission device, the rise time of the drive voltage Vin (the drive voltage Vin is a negative predetermined voltage for electron accumulation from the first voltage Vm for electron emission). It has been found that the amount of electrons emitted from the electron-emitting device (amount of emitted electrons) is increased by shortening Trise (the time required to change to the second voltage Vp, which is a positive predetermined voltage). To shorten the rise time Trise of the drive voltage Vin means to increase the change speed (voltage change rate) α (α = dVin / dt, that is, the slope) of the drive voltage Vin.

  FIG. 37 schematically shows a measurement circuit used for examining the relationship between the rise time Trise of the drive voltage Vin and the amount of emitted electrons. In this measurement circuit, an electron emission device 70 is used. Similar to the electron emission device 40 shown in FIG. 30, the electron emission device 70 includes an electron emission element D including a lower electrode 12, an emitter portion 13, and an upper electrode 14. On the upper electrode side of the element D, a collector electrode 18 ′, a phosphor 19 ′, and a transparent plate 17 included in the electron emission device 50 shown in FIG. 32 are arranged so as to face the upper electrode 14.

  The lower electrode 12 is connected to one terminal of a power supply (drive voltage applying circuit) 71 via a first resistor R1, and to the negative electrode of a constant voltage source 72 for applying a collector voltage Vc via a first resistor R1. Connected. The positive electrode of the constant voltage source 72 is connected to the collector electrode 18 'via the second resistor R2. The upper electrode 14 is connected to the other terminal of the power source 71. A light output measuring device (avalanche photo diode) APD is disposed on the transparent plate 17. The APD outputs a voltage (APD output voltage) Vapd corresponding to the magnitude of the light output generated by the phosphor 19 '.

  The power supply 71 generates a pulse voltage as will be described later. Thus, when electrons are emitted through the upper electrode 14 of the generating element D, the collector current Ic in the direction shown in FIG. 37 flows. Therefore, by integrating the collector current Ic over one pulse period generated by the power source 71, the amount of electrons (amount of emitted electrons) SIc associated with one emission (electron emission) is measured. Similarly, by integrating the APD output voltage Vapd over one pulse period, a value SVapd corresponding to the amount of light accompanying one light emission is obtained. This value SVapd is a value substantially proportional to the amount of emitted electrons. Therefore, by comparing this value SVapd with the amount of emitted electrons SIc obtained by integrating the collector current Ic, it can be confirmed that the amount of emitted electrons SIc can be measured correctly.

  FIG. 38 is a time chart showing the results of measuring the collector current Ic and the APD output voltage Vapd when the drive voltage Vin is variously changed. In this measurement, the drive voltage Vin is maintained at the first voltage Vm (−50 V), which is a negative predetermined voltage, for a predetermined time (about 4 ms). During this period, electrons are accumulated on the upper portion of the emitter section 13. Next, the drive voltage Vin is increased to the second voltage Vp (200 V), which is a positive predetermined voltage, in proportion to the time over the rise time Trise. The size of the first resistor R1 is 1 kΩ.

  In FIG. 38, the line L10 shows the drive voltage Vin when the rise time Trise of the drive voltage Vin is 0 (ms), and the line M10 and the line N10 give the drive voltage Vin shown in the line L10 to the element D. In this case, the collector current Ic and the APD output voltage Vapd are shown. A line L11 indicates the drive voltage Vin when the rise time Trise of the drive voltage Vin is 1 (ms), and a line M11 and a line N11 indicate collectors when the drive voltage Vin indicated by the line L11 is applied to the element D. Current Ic and APD output voltage Vapd are shown. Similarly, the line L12 indicates the drive voltage Vin when the rise time Trise of the drive voltage Vin is 2 (ms), and the line M12 and the line N12 are collectors when the drive voltage Vin indicated by the line L12 is applied. Current Ic and APD output voltage Vapd are shown.

  Similarly, the line L13 indicates the drive voltage Vin when the rise time Trise of the drive voltage Vin is 4 (ms), and the line M13 and the line N13 apply the drive voltage Vin indicated by the line L13 to the element D. In this case, the collector current Ic and the APD output voltage Vapd are shown. A line L14 indicates the drive voltage Vin when the rise time Trise of the drive voltage Vin is 6 (ms), and a line M14 and a line N14 indicate collectors when the drive voltage Vin indicated by the line L14 is applied to the element D. Current Ic and APD output voltage Vapd are shown.

  FIG. 39 is a graph showing the relationship between the amount of emitted electrons SIc and the value SVapd with respect to the rise time Trise of the drive voltage Vin in the same measurement.

  As is apparent from FIGS. 38 and 39, the amount of emitted electrons increases as the rise time Trise of the drive voltage (lighting voltage) Vin is shortened (that is, the voltage change rate α of the drive voltage Vin is increased). The reason for this can be considered as follows.

  As described above, when the first voltage Vm, which is a negative predetermined voltage, is applied to the element D, electrons are accumulated (charged) on the surface of the emitter section 13. Thereafter, when a second voltage Vp (lighting voltage, electron emission voltage), which is a positive predetermined voltage, is applied to the element D, the dipole of the emitter section 13 is inverted (polarization inversion). Along with this, a part of the electrons on the surface of the emitter section 13 moves along the upper portion of the emitter section 13 (the portion where the surface resistance of the emitter section 13 is generated), and the emitter section 13 and the upper electrode 14 are in contact with each other. It is recovered by the upper electrode 14 at the part where it is. The remaining electrons are emitted above the emitter section 13. At that time, some of the electrons are collected by the upper electrode 14 and only the remaining electrons reach the collector electrode 18 '.

  When the rise time Trise of the drive voltage Vin is shortened, the above-described polarization inversion speed increases. Therefore, before the electrons accumulated in the upper part of the emitter part 13 move on the upper part of the emitter part 13 and are collected by the upper electrode 14, many dipoles (that are rapidly inverted in polarity at the upper part of the emitter part 13 ( The repulsive force that increases rapidly from the negative electrode) is emitted to the upper portion of the emitter section 13. As a result, the amount of electrons emitted upward from the emitter section 13 increases.

  Furthermore, the electrons emitted upward from the emitter section 13 are strongly accelerated due to the high polarization inversion speed. Therefore, the initial velocity at the time of emission of these electrons increases. As a result, of the electrons emitted upward from the emitter section 13, the proportion of electrons collected by the upper electrode 14 decreases, and the proportion of electrons emitted through the fine through holes of the upper electrode 14 increases.

  As described above, the shorter the rise time Trise of the drive voltage Vin, the lower the proportion of electrons that move above the emitter section 13 and are collected by the upper electrode 14, and electrons emitted above the emitter section 13. It is presumed that the amount of emitted electrons increases as the ratio increases and the ratio of the electrons recovered by the upper electrode 14 among the electrons emitted upward from the emitter section 13 decreases. Note that when the magnitude of the first resistor R1 is 1 kΩ as described above and the rise time Trie of the drive voltage Vin is 0 (ms), the actual rise time (actual rise time) is that of the first resistor R1. It becomes 0.15 (ms) under the influence. On the other hand, when the magnitude of the first resistor R1 is 500Ω and the rise time Trise of the drive voltage Vin is 0 (ms), the actual rise time is 0.1 (ms), and the first resistor R1 The size is shorter than when the size is 1 kΩ. As a result, as shown in FIG. 39, when the rise time Trise of the drive voltage Vin is set to 0 (ms), the first resistor R1 is larger when the first resistor R1 is 500Ω. Since the actual rise time is shorter than when 1 kΩ is set to 1 kΩ, a result consistent with the above conclusion that the amount of emitted electrons SIc increases was confirmed.

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. It is the figure which showed one state of the electron emission apparatus shown in FIG. It is a graph of the voltage-polarization characteristic of the emitter part shown in FIG. 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 emission apparatus shown in FIG. It is the figure which showed the other state of the electron emission apparatus shown in FIG. It is the figure which showed the other state of the electron emission apparatus shown in FIG. It is the figure which showed the other state of the electron emission apparatus shown in FIG. It is the figure which showed the other state of the electron emission apparatus shown in FIG. It is the figure which showed the mode of the electron discharge | released by the electron emission apparatus 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 time chart which showed the drive voltage, element voltage, and element current at the time of changing a drive voltage waveform. It is the time chart which showed the drive voltage, element voltage, and element current at the time of changing a drive voltage waveform. 2 is a time chart showing drive voltage, device voltage, device current, and light output of the electron emission device shown in FIG. 1. FIG. 2 is a circuit diagram of a drive voltage application circuit, a focusing electrode potential application circuit, and a collector voltage application circuit shown in FIG. 1. It is the time chart which showed the drive voltage and element voltage of the electron emission apparatus which concern on 2nd Embodiment of this invention. It is the time chart which showed the drive voltage and element voltage of the electron emission apparatus which concern on 3rd Embodiment of this invention. It is the time chart which showed the drive voltage and element voltage of the electron emission apparatus which concern on 4th Embodiment of this invention. It is a circuit diagram of the electron emission apparatus which concerns on 5th Embodiment of this invention. It is the time chart which showed the drive voltage in the electron emission apparatus shown in FIG. It is the time chart which showed the drive voltage of the electron emission apparatus which concerns on 6th Embodiment of this invention, element voltage, element current, and optical output. It is a circuit diagram of the electron emission apparatus which concerns on 7th Embodiment of this invention. It is a time chart for demonstrating the action | operation of the electron emission apparatus shown in FIG. It is a fragmentary sectional view of the electron emission apparatus which concerns on 8th 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. 36 is another partial cross-sectional view of the electron emission device shown in FIG. 35. It is a circuit diagram of the measurement circuit used in order to investigate the relationship between the rise time of a drive voltage, and the amount of emitted electrons. It is a time chart which shows the mode of the change of the output voltage of the collector current and optical output measuring device when changing a drive voltage variously. It is the graph which showed the relationship with the value which shows the light quantity based on the amount of emitted electrons with respect to the rise time of a drive voltage when a drive voltage is variously changed, and the output of an optical output measuring device. It is a fragmentary sectional view of an electron emission device to which the present invention is not applied. It is a time chart which showed the drive voltage, collector voltage, and optical output in the electron emission apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electron emission apparatus, 11 ... Board | substrate, 12 ... Lower electrode, 13 ... Emitter part, 14 ... Upper electrode, 14a ... Fine through-hole, 15 ... Insulating layer, 16 ... Focusing electrode, 17 ... Transparent plate, 18 ... Collector electrode 19 ... phosphor, 19B ... blue phosphor, 19R ... red phosphor, 19G ... green phosphor, 21 ... drive voltage application circuit, 21s ... power supply, 22 ... focusing electrode potential application circuit, 23 ... collector voltage application circuit.

Claims (11)

A dielectric emitter, a lower electrode formed under the emitter, and an upper portion of the emitter so as to face the lower electrode across the emitter and a plurality of fine through holes are formed. An element having an upper electrode,
A driving voltage applying means including a power supply and a circuit for applying a voltage generated by the power supply between the lower electrode and the upper electrode;
An electron emission device comprising:
The power supply is
A first voltage is generated so that a device voltage, which is a potential difference between the lower electrode and the upper electrode with respect to the potential of the lower electrode, as a predetermined negative voltage is generated from the upper electrode to the emitter section. The electrons are supplied to the emitter section and accumulated in the emitter section. After that, a voltage that gradually increases toward the second voltage is generated and accumulated in the emitter section so that the element voltage becomes a predetermined positive voltage. An electron emission device that emits electrons from the emitter. The electron emission device according to claim 1, wherein
The power supply is
After the first voltage is generated, the device voltage is between the negative predetermined voltage and the positive predetermined voltage without further accumulating electrons in the emitter section and releasing electrons from the emitter section. A voltage that increases from the first voltage toward the third voltage is generated so as to be an intermediate voltage, and then increases from the first voltage toward the second voltage from the first voltage toward the second voltage. An electron-emitting device configured to generate a voltage that increases more slowly than when performing. The electron-emitting device according to claim 1 or 2,
The power supply is
The voltage increase start time in the period from the voltage increase start time at which generation of the voltage gradually increasing toward the second voltage to the second voltage arrival time at which the voltage reaches the second voltage. An electron emitting device configured to generate a voltage that gradually increases during a period from the time when the positive polarity reversal is completed to the time when the reversal of the polarization of the emitter portion is substantially completed. The electron emission device according to claim 1, wherein
The power supply is
During the period from the voltage increase start time at which generation of the voltage gradually increasing toward the second voltage to the second voltage arrival time at which the voltage reaches the second voltage, the polarization of the emitter section An electron-emitting device configured to generate a voltage that gradually increases during a period from the time when positive-side polarization reversal is completed to the time when the second voltage is reached. A dielectric emitter, a lower electrode formed under the emitter, and an upper portion of the emitter so as to face the lower electrode across the emitter and a plurality of fine through holes are formed. An element having an upper electrode,
A driving voltage applying means including a power supply and a circuit for applying a voltage generated by the power supply between the lower electrode and the upper electrode;
An electron emission device comprising:
The power supply is
A second voltage is generated and stored in the emitter section so that the element voltage, which is a potential difference between the lower electrode and the upper electrode with respect to the potential of the lower electrode, is a predetermined positive voltage. The electrons are emitted from the emitter, and then a voltage that gradually decreases toward the first voltage is generated so that the element voltage becomes a predetermined negative voltage, and the electrons are supplied from the upper electrode to the emitter. An electron emission device for storing the electrons in the emitter. The electron emission device according to claim 5, wherein
The power supply is
After generating the second voltage, the element voltage is intermediate between the negative predetermined voltage and the positive predetermined voltage without accumulating electrons in the emitter section and emitting electrons from the emitter section. When a voltage that decreases from the second voltage to the third voltage is generated so as to be a voltage, and then decreases from the second voltage to the third voltage from the third voltage toward the first voltage. An electron-emitting device configured to generate a voltage that decreases more slowly. The electron emission device according to claim 5 or 6,
The power supply is
In the period from the voltage decrease start time at which generation of the voltage gradually decreasing toward the first voltage to the first voltage arrival time at which the voltage reaches the first voltage, the voltage decrease start time An electron emission device configured to generate a voltage that gradually decreases during a period from the time when the negative polarity reversal is completed to the time when the reversal of the polarization of the emitter portion is substantially completed. 5. The electron emission device according to claim 4, wherein
The power supply is
The polarization of the emitter section during a period from a voltage decrease start time at which generation of the voltage gradually decreasing toward the first voltage starts to a first voltage arrival time at which the voltage reaches the first voltage. An electron emission device configured to generate a voltage that decreases most slowly during a period from the time when the negative side polarization reversal is completed to the time when the first voltage is reached. The electron-emitting device according to any one of claims 1 to 8,
The power supply is
The first voltage and the second voltage are configured to be alternately and repeatedly generated,
The drive voltage applying means is
A first period from a voltage decrease start time at which generation of the voltage decreasing toward the first voltage starts to a time point when the negative polarization inversion of the emitter section is substantially completed during the decrease of the voltage. Circuit elements inserted into the circuit in a period;
A circuit element inserted into the circuit in a second period from completion of the negative polarization inversion to completion of accumulation of electrons in the emitter section; and
A third period from a voltage increase start time at which generation of the voltage increasing toward the second voltage starts to a positive polarization inversion completion point at which the polarization inversion of the emitter section is substantially completed during the increase of the voltage. A circuit element inserted into the circuit in a period;
A circuit element that is inserted into the circuit in a fourth period from the completion of the positive side polarization reversal to the completion of electron emission from the emitter section,
An electron emission apparatus comprising circuit constant setting means for setting circuit constants of the circuit by selecting the circuit elements so that at least two of the circuit elements are different from each other and inserting the circuit elements into the circuit. A dielectric emitter, a lower electrode formed under the emitter, and an upper portion of the emitter so as to face the lower electrode across the emitter and a plurality of fine through holes are formed. An element having an upper electrode,
A first voltage is generated so that a device voltage, which is a potential difference between the lower electrode and the upper electrode with respect to the potential of the lower electrode, as a predetermined negative voltage is generated from the upper electrode to the emitter section. The electrons are supplied to the emitter section, and the electrons are accumulated in the emitter section. Thereafter, a second voltage is generated so that the element voltage is a predetermined positive voltage, and the electrons accumulated in the emitter section are removed from the emitter section. A drive voltage applying means including a power supply configured to be discharged and a circuit for applying a voltage generated by the power supply between the lower electrode and the upper electrode;
In an electron emission device comprising:
The power supply is
The first voltage and the second voltage are configured to be alternately and repeatedly generated,
The drive voltage applying means is
A first period from a voltage decrease start time at which generation of a voltage that decreases toward the first voltage starts to a time point at which the polarization inversion of the emitter section is substantially completed during the decrease of the voltage. A circuit element inserted into the circuit in
A circuit element inserted into the circuit in a second period from completion of the negative polarization inversion to completion of accumulation of electrons in the emitter section; and
A third period from a voltage increase start time at which generation of a voltage increasing toward the second voltage starts to a positive polarization inversion completion point at which the polarization inversion of the emitter section is substantially completed during the increase of the voltage. A circuit element inserted in the same circuit in
A circuit element that is inserted into the circuit in a fourth period from the completion of the positive side polarization reversal to the completion of electron emission from the emitter section,
An electron emission apparatus comprising circuit constant setting means for setting circuit constants of the circuit by selecting the circuit elements so that at least two of the circuit elements are different from each other and inserting the circuit elements into the circuit. A dielectric emitter, a lower electrode formed under the emitter, and an upper portion of the emitter so as to face the lower electrode across the emitter and a plurality of fine through holes are formed. An element having an upper electrode,
A driving voltage applying means including a power supply and a circuit for applying a voltage generated by the power supply between the lower electrode and the upper electrode;
In an electron emission device comprising:
The power supply is
In order to supply electrons from the upper electrode to the emitter section and accumulate the electrons in the emitter section, a fourth voltage, which is a negative voltage that causes polarization inversion in the emitter section, is obtained. When the negative side polarization reversal is completed, or at a predetermined time before the completion of the negative side polarization reversal, the fifth voltage, which is a negative voltage smaller than the fourth voltage, is obtained. An electron-emitting device configured to generate a voltage that gradually decreases toward a first voltage that is a negative voltage having a magnitude greater than that of a fifth voltage.

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