JP2006338966A - Electronic device, display device using it and sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the inside of an envelope of an electronic device in a high vacuum state by a simple structure. <P>SOLUTION: This field emission type display device 10 is provided with getters 60 and resistors 62 in the envelope 40 composed of: a cathode 16 having a flat electron emission source 44; an anode 18 for receiving electrons emitted from the cathode 16 in a flat form; and spacers 22. The resistors 62 are formed on a cathode substrate 26 in a semiconductor fabrication process. The getters 60 are formed on the resistors 62. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic device including an electron emission source, and a display device and a sensor using the electronic device.

  2. Description of the Related Art In recent years, flat display devices are becoming mainstream for display devices used in computer monitors and televisions. Examples of the flat display device include a plasma display panel (PDP), a liquid crystal display (LCD), and a field emission display (FED).

  Among these, field emission display devices have advantages such as self-emission, easy thinning, and high durability, and have been actively researched and developed recently. The field emission display device emits light by colliding electrons emitted from a flat electron emission source provided on a cathode with a phosphor provided on an anode facing the cathode.

In the field emission display device, it is necessary to keep the inside of the envelope containing the electron emission source and the phosphor at a high vacuum, for example, 10 ⁻⁶ Torr or less. This is because when gas is generated in the envelope and the pressure increases, the effect varies depending on the type of gas, but it adversely affects the electron emission source, reducing the amount of emitted electrons and lowering the brightness of the display device. It is. Further, the generated gas is ionized by an electron beam to become ions, which are accelerated by an electric field for accelerating the electrons and collide with the electron emission source, thereby damaging the electron emission source.

  When forming the envelope, even if the inside of the envelope is sealed to a high vacuum, the degree of vacuum is reduced by the outgas emitted from the phosphor, glass, electron emission source, etc. in the envelope. . This outgas can be reduced to some extent by baking or the like, but it is difficult to completely remove the outgas.

  In order to keep the inside of the envelope in a high vacuum, a method of providing a getter in the envelope has been proposed. A getter is a substance capable of physically and chemically adsorbing a residual gas existing in a vacuum. For example, Ti, Ba, etc. are known to have a getter action.

As a method of installing the getter in the envelope, a wire getter with a getter attached to the outer periphery of the wire is provided on the periphery of the envelope, and the getter is evaporated by energizing the wire, A method for depositing a getter film has been proposed (Patent Document 1).
JP-A-5-151916

  However, in the case of the method of Patent Document 1, a wire getter with a complicated structure must be prepared separately, and the structure of the envelope in which the wire getter is installed and the manufacturing process become complicated. There is a problem in terms of cost.

  The present invention has been made in view of these problems, and an object of the present invention is to provide an electronic device capable of maintaining a high vacuum inside the envelope with a simple structure, and a display device and a sensor using the electronic device. There is to do.

  In order to solve the above-described problems, an electronic device according to an aspect of the present invention is an electronic device including a cathode having a planar electron emission source and an anode that planarly receives electrons emitted from the cathode. In the semiconductor manufacturing process that is carried out when manufacturing at least one of the anode and the cathode, and at least one of the anode and the cathode And a getter provided in the vicinity of the resistor.

  According to this aspect, the getter provided in the vicinity of the resistor can be heated by energizing the resistor built in at least one of the anode and the cathode. Since the heated and activated getter adsorbs the outgas in the envelope of the electronic device, the inside of the envelope can be kept at a high vacuum. Since the resistor can be formed in a semiconductor manufacturing process that is performed when at least one of the anode and the cathode is manufactured, a simple structure can be achieved.

  The getter may be provided in contact with the resistor. The getter may be provided separately from the resistor.

  The resistor and the getter may be provided at a position away from the electron emission region of the cathode. The distance between the anode and the cathode may be 2 mm or less.

  The getter may be formed of one or more kinds of metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, W, and Ba, or an alloy containing one or more kinds of these metals. The resistor may be formed of polysilicon.

  The resistance value and the energization amount of the resistor may be determined from the volume of the envelope and the temperature necessary for activating the getter. In this case, the resistance value of the resistor and the energization amount can be suitably determined according to the volume of the envelope and the type of getter.

  Another embodiment of the present invention is a display device. This device includes the above-described electronic device, and a light emitting layer that emits light by collision of electrons is provided on the anode of the electronic device. According to this aspect, it is possible to provide a display device in which the inside of the envelope is maintained at a high vacuum.

  Yet another embodiment of the present invention is a sensor. This sensor includes the above-described electronic device, and a photoelectric conversion film is provided on the anode of the electronic device. According to this aspect, it is possible to provide a sensor in which the inside of the envelope is maintained at a high vacuum.

  According to the present invention, the inside of the envelope of the electronic device, the display device, and the sensor can be kept in a high vacuum with a simple structure.

  Hereinafter, the display device 10, the electronic device 12, and the sensor 70 according to embodiments of the present invention will be described with reference to the drawings. In addition, since each drawing aims at explaining the positional relationship of each member, it does not necessarily represent the actual dimensional relationship of each member. Further, in each embodiment, the same or corresponding components are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate.

  First, a display device 10 according to an embodiment of the present invention will be described with reference to FIG. The electronic device 12 according to the embodiment of the present invention will be described as a component of the display device 10 together.

  FIG. 1 shows a cross section of a display device 10 according to an embodiment of the present invention. The display device 10 mainly includes an electronic device 12 and a phosphor 14. The electronic device 12 includes an envelope 40, a cathode power source 52, a gate power source 54, an anode power source 56, and a current control unit 58.

  The envelope 40 includes a cathode 16, an anode 18, and a spacer 22. The cathode 16 includes a cathode substrate 26, a cathode electrode 42, and an electron emission source 44. The anode 18 includes an anode electrode 46 and an anode substrate 48.

  The cathode substrate 26 is made of an insulator such as a glass plate. The visible light transmittance of the cathode substrate 26 does not matter. The cathode substrate 26 only needs to be formed of an insulating member on the surface, and in addition to a glass substrate, a quartz substrate or a semiconductor substrate having an insulating film formed on the surface can be used.

  The cathode electrode 42 is a conductor formed on the cathode substrate 26. The cathode electrode 42 is formed by depositing a metal such as Cu, Mo, Ni, or Ta, for example. The electron emission source 44 is formed in a planar shape on the cathode electrode 42. The electron emission source 44 has a conical shape and emits electrons from a pointed portion. The electron emission source 44 is formed by evaporating a metal such as Cu or Mo, for example. The electron emission source 44 may be made of a material other than metal, for example, a carbon material having conductivity such as a carbon nanotube or diamond. A plurality of electron emission sources 44 are formed in a matrix on the cathode electrode 42.

Around the electron emission source 44, an insulator layer 50 having a cylindrical hole in which the electron emission source 44 is installed is formed. Insulator layer 50 is formed, for example, by depositing the SiO _2. On the insulator layer 50, the gate electrode 20 is formed. The gate electrode 20 has a hole having a smaller diameter than that of the insulator layer 50, and is made of a metal film such as Mo, Ta, or Cr.

  In the embodiment of the present invention, as shown in FIG. 1, a resistor 62 and a getter 60 are provided at a position away from the electron emission region 38 of the cathode substrate 26. For example, you may provide in the position about 5 mm away from the peripheral part of the electron emission area | region 38. FIG.

The resistor 62 can be formed on the cathode substrate 26 in a semiconductor manufacturing process performed when the cathode 16 is manufactured. Polysilicon can be used as the material of the resistor 62. When polysilicon is used, an SiO ₂ film is formed on the cathode substrate 26 using a CVD method or the like, and a polysilicon film is formed thereon. Thereafter, the resistor 62 is formed by photolithography. The resistance value can be controlled by doping polysilicon or the like with impurities such as B and P. The resistor 62 is wired to be drawn out of the envelope 40 by Au, Pt, Al, or the like, and is connected to the current control unit 58.

  The getter 60 is provided in the vicinity of the resistor 62. For example, as shown in FIG. The getter 60 can be formed by forming a film using a semiconductor manufacturing process, for example, a vacuum deposition method or a sputtering method. The area, thickness, etc. of the getter 60 are set based on the size of the envelope 40. Further, the getter 60 processed into a predetermined shape such as a rod shape or a strip shape may be mechanically fixed on the resistor 62.

  The getter 60 is made of one or more kinds of metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, and W, or an alloy containing one or more kinds of these metals. Al, Fe, Ni, etc. may be included as a component of the alloy. These are non-evaporable getter materials, and the getter 60 is heated and activated by the heat generated by energizing the resistor 62. The getter activation means that a nitride film or an oxide film on the surface of the getter is diffused to expose a clean metal surface on the outermost surface, thereby causing a getter action. For example, in the case of Ti, the getter is activated by heating to about 400 ° C. to 420 ° C.

The getter 60 may be a so-called evaporation type getter using Ba or an alloy containing Ba as a main component, for example, BaAl ₄ . A getter using BaAl ₄ evaporates at about 850 ° C. and forms a deposited film in the envelope 40. When using an evaporation type getter, it is desirable to form the getter 60 and the resistor 62 at a position away from the electron emission region 38 of the cathode 16, for example, at a position 5 mm or more away from the electron emission region 38. This prevents the evaporated getter from adhering to the electron emission source 44 and lowering the electron emission performance, or preventing the evaporated getter from adhering to the phosphor 14 to lower the light emission performance. it can.

  The anode 18 is a member that planarly receives electrons emitted from the cathode 16. The anode 18 is made of a material that transmits visible light. That is, the anode electrode 46 can be formed, for example, by depositing ITO. Instead, the anode electrode 46 may be formed, for example, by thinly depositing a metal such as Mo or Ta to ensure visible light transmission. The anode substrate 48 can be made of, for example, a glass material such as plate glass, a transparent resin material such as polycarbonate, or a transparent ceramic such as quartz.

  The phosphor 14 is formed in a thin film shape on the anode electrode 46. The phosphor 14 is a light emitting layer that emits light by collision of electrons emitted from the cathode 16, and is made of, for example, a material in which Zn is bonded to ZnO.

  The cathode 16 and the anode 18 configured as described above are arranged so that the electron emission source 44 and the phosphor 14 face each other and are parallel to each other. The envelope 40 is configured. The envelope 40 hermetically covers a space in which electrons emitted from the cathode 16 fly. The distance between the cathode 16 and the anode 18 is desirably about 0.5 mm to 2 mm, for example, about 1 mm.

The joining is performed by attaching frit glass to the joint and heating it to about 400 ° C. for firing. As described above, in the field emission display device, the inside of the envelope 40 must be kept in a high vacuum. Therefore, it is desirable to perform firing in a state where the inside of the firing furnace is kept at a high vacuum. In this case, the inside of the envelope 40 is in a high vacuum. Further, after firing in the atmosphere, the gas in the envelope 40 may be exhausted, and the inside of the envelope 40 may be set to a high vacuum by sealing the exhaust port. The degree of vacuum is desirably 1 × 10 ⁻⁶ Torr or less.

  Since the getter 60 is activated by the heating during firing, the degree of vacuum in the envelope is initially increased, but the degree of vacuum gradually deteriorates due to the outgas discharged from the members in the envelope. In this case, by energizing the resistor 62 and activating the getter 60 again, the inside of the envelope can be maintained at a high vacuum. For example, the resistor 62 may be energized by measuring the predetermined time by the current controller 58 having a microprocessor and controlling the current controller 58.

  The operation of the display device 10 configured as described above will be described. First, a potential is applied from the cathode power source 52 to the cathode electrode 42 and from the gate power source 54 to the gate electrode 20 so that the gate electrode 20 has a positive potential with respect to the electron emission source 44. A potential is also applied to the anode electrode 46 from the anode power source 56 so that the anode electrode 46 has a positive potential with respect to the electron emission source 44. As a result, electric field concentration occurs at the tip of the electron emission source 44, and electrons are emitted from the electron emission source 44 into a high vacuum space.

  The electrons emitted from the electron emission source 44 reach the anode 18 along the electric field generated between the cathode 16 and the anode 18 and collide with the phosphor 14. The phosphor 14 emits light when electrons collide with it. The light a emitted in this way is seen through the anode electrode 46 and the anode substrate 48. Since a plurality of electron emission sources 44 are formed in a matrix, an image can be displayed on the display device 10 by controlling each electron emission source 44.

  In the present embodiment, the resistor 62 and the getter 60 are formed on the cathode substrate 26, but these may be formed on the anode substrate 48 and formed on at least one of the cathode substrate 26 and the anode substrate 48. It only has to be done.

  Further, the getter 60 and the resistor 62 may be provided apart from each other. FIG. 2 is a view showing a cross section of the display device 10 in which the getter 60 and the resistor 62 are provided apart from each other. As shown in FIG. 2, the getter 60 is formed on the anode substrate 48 and the resistor 62 is formed on the cathode substrate 26 so as to face each other. The getter 60 is activated by radiant heat generated by energizing the resistor 62. In FIG. 2, since the purpose is to explain the positional relationship between the members, the gap between the getter 60 and the resistor 62 is shown enlarged, but it is actually located at a very close distance.

  An example of the resistance value of the resistor 62 necessary for activating the getter 60 and the energization amount will be shown. Assume that the resistor 62 is made of polysilicon, and its volume is 5 mm × 2 mm × 10 μm. If the resistance value of the resistor 62 is set to 18 kΩ, for example, and energized for 0.1 second at a voltage of 180 V and a current of 0.01 A, the generated energy becomes 0.18 J. Since silicon has a specific heat of 0.183 cal / deg · g and a specific gravity of 2.35, if all of this energy increases the temperature of the polysilicon, the temperature of the polysilicon instantaneously increases by 1000 ° C. The getter 60 can be activated by the radiant heat and heat conduction from the heated resistor 62. The resistance value and the energization amount of the resistor 62 may be determined from the volume of the envelope 40 and the temperature necessary for activating the getter 60.

  Next, a sensor 70 using the electronic device 12 according to the embodiment of the present invention will be described with reference to FIG.

  FIG. 3 shows a cross section of a sensor 70 according to an embodiment of the present invention. The sensor 70 mainly includes an electronic device 12, a photoelectric conversion film 72, and a control unit 74. The operation of the sensor 70 is as follows. First, light b from the imaging object enters the sensor 70 from the outside of the anode substrate 48. The light b is incident on the photoelectric conversion film 72, and electron-hole pairs are formed in the photoelectric conversion film 72. The holes are collected on the cathode 16 side of the photoelectric conversion film 72 by the electric field between the anode 18 and the cathode 16.

  Next, electrons emitted from the electron emission source 44 collide with the photoelectric conversion film 72. This electron collision is detected by the control unit 74 as a current between the anode 18 and the cathode 16 at a location where holes of the photoelectric conversion film 72 exist, that is, a location where light is incident on the photoelectric conversion film 72. . On the other hand, no current flows between the anode 18 and the cathode 16 at a place where the light does not enter the photoelectric conversion film 72. In this way, the part where the current flows and the part where the current does not flow are detected by the control unit 74, thereby recognizing the part where the light is incident on the sensor 70 and the part where the light is not incident. Since a plurality of electron emission sources 44 are formed in a matrix, the image of the imaging target can be recognized.

  In the sensor 70 as well, by energizing the resistor 62 and activating the getter 60 by the generated heat, the inside of the envelope 40 can be kept in a high vacuum, and deterioration of the characteristics of the sensor 70 can be prevented. .

  Although the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications such as design changes may be added based on the knowledge of those skilled in the art. Embodiments which are possible and which have been modified are also included in the scope of the present invention.

It is a figure which shows the cross section of the display apparatus which concerns on embodiment of this invention. It is a figure which shows the cross section of the display apparatus which provided the getter and the resistor apart. It is a figure which shows the cross section of the sensor which concerns on embodiment of this invention.

Explanation of symbols

  10 display devices, 12 electronic devices, 16 cathodes, 18 anodes, 22 spacers, 38 electron emission regions, 40 envelopes, 44 electron emission sources, 60 getters, 62 resistors.

Claims (10)

In an electronic device comprising: a cathode having a planar electron emission source; and an anode that planarly receives electrons emitted from the cathode;
An envelope that airtightly covers a space in which electrons emitted from the cathode and reach the anode fly.
In a semiconductor manufacturing process carried out when producing at least one of the anode and the cathode, at least a resistor built in one of the anode and the cathode;
A getter provided in the vicinity of the resistor;
An electronic device comprising:   The electronic device according to claim 1, wherein the getter is provided in contact with the resistor.   The electronic device according to claim 1, wherein the getter is provided apart from the resistor.   4. The electronic device according to claim 1, wherein the resistor and the getter are provided at positions separated from an electron emission region of the cathode. 5.   The electronic device according to claim 1, wherein a distance between the anode and the cathode is 2 mm or less.   The getter is formed of one or more metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, W, and Ba, or an alloy containing one or more of these metals. The electronic device according to claim 1.   The electronic device according to claim 1, wherein the resistor is made of polysilicon.   8. The electronic device according to claim 1, wherein a resistance value and an energization amount of the resistor are determined from a volume of the envelope and a temperature necessary for activating the getter.   A display device comprising the electronic device according to claim 1, wherein a light emitting layer that emits light by collision of electrons is provided at an anode of the electronic device.   A sensor comprising the electronic device according to claim 1, wherein a photoelectric conversion film is provided on an anode of the electronic device.

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