Patent Grant
7728501
1. Field of the Invention
The present invention relates to an image display apparatus and a video signal receiving and display apparatus that are used for television receivers and computer display apparatuses.
2. Description of the Related Art
Field emission display apparatuses, which are one type of flat panel display apparatus, are known.
In field emission display apparatuses, electrons emitted from an electron emitting device to an anode need to be accelerated by applying a high voltage to between the electron emitting device and the anode including a light emitting material, such as a fluorescent member. Accordingly, a high electric field intensity must be maintained between a faceplate having the anode mounted thereon and a rear plate having the electron emitting device mounted thereon.
Additionally, a spacer is disposed between the rear plate and the faceplate to maintain a certain distance therebetween. However, the electric field tends to concentrate at a corner of the spacer in the longitudinal direction and the structure such as a securing member for securing the spacer due to the geometric effect. To reduce the electric field concentration at the corner of the spacer and that structure, an electrode having a potential that is lower than that of the anode may be disposed on the faceplate at a position separated from the anode.
To reduce electric discharge occurring around the connection point between the electrode having the potential that is lower than that of the anode and the spacer, Japanese Patent Laid-Open No. 2002-237268 describes a technology in which an electrode is provided on the surface of the spacer so as to be connected to the electrode having the potential that is lower than that of the anode.
In addition, to prevent the occurrence of non-uniform distribution of the electric potential of the spacer, Japanese Patent Laid-Open No. 2002-367540 describes a technology in which the surface resistance value of a region of the spacer between the anode and the electrode having the potential that is lower than that of the anode is increased to a value higher than that of the region of the spacer corresponding to the anode.
However, when the electrode having the potential that is lower than that of the anode is provided, electric discharge sometimes occurs between the electrode having the potential that is lower than that of the anode and the anode.
In addition, to reduce the size of the image display apparatus, it is desirable that a non-image display region of the image display apparatus, which is a region other than an image display unit (typically a region where the anode is disposed), is reduced. Accordingly, it is desirable that the distance between the electrode having the potential that is lower than that of the anode and being disposed in the non-image display region and the anode is decreased. Furthermore, it is desirable that the displayed image has high contrast and high resolution. One method of increasing the contrast of the displayed image is to increase the voltage applied to between the electron emitting device and the anode. One method of increasing the resolution of the displayed image is to decrease the distance between the electron emitting device and the anode.
However, in the method described in Japanese Patent Laid-Open No. 2002-237268 in which an electrode is provided on the surface of the spacer so as to be connected to the electrode having the potential that is lower than that of the anode, the electric field intensity around the electrode connected to the electrode having the potential that is lower than that of the anode becomes high. Therefore, electric discharge may occur.
Similarly, in the structure described in Japanese Patent Laid-Open No. 2002-367540, the electric field concentrates in an area around the connection point between the spacer and the electrode having the electric potential that is lower than that of the anode. Therefore, the electric discharge from the area around the connection point may occur.
Accordingly, to reduce the electric discharge, it is desirable that the electric field concentration on the electrode having the potential that is lower than that of the anode is further reduced.
Accordingly, the present invention provides an image display apparatus for further reducing the electric field concentration on the electrode having the potential that is lower than that of the anode so as to reduce the occurrence of electric discharge.
According to an embodiment of the present invention, an image display apparatus includes (a) an envelope, (b) a first electroconductive member, a second electroconductive member, and a third electroconductive member disposed in the envelope, (c) a plate-like spacer disposed between the first electroconductive member and the third electroconductive member and between the second electroconductive member and the third electroconductive member, and (d) a circuit for supplying an electric potential to the first electroconductive member and supplying an electric potential that is lower than the electric potential of the first electroconductive member to the second electroconductive member and the third electroconductive member. When a sheet resistance between a first region of the plate-like spacer to which the electric potential is supplied from the first electroconductive member and a second region of the plate-like spacer to which the electric potential is supplied from the second electroconductive member is defined as ρf [Ω/□], and a sheet resistance between a third region of the plate-like spacer to which the electric potential is supplied from the third electroconductive member and a region located between the first region and the second region is defined as ρr [Ω/□], a condition 1/100<ρr/ρf≦40 is satisfied.
According to the present invention, the image display apparatus can be provided that reduces the electric field concentration on the electrode having the potential that is lower than that of the anode so as to reduce the occurrence of electric discharge.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings.
An exemplary structure of an image display apparatus according to a first exemplary embodiment of the present invention is described below with reference to
The x-direction wiring 4 is disposed on the surface of the rear plate 1 adjacent to the faceplate 2. The anode 5 is disposed on the surface of the faceplate 2 adjacent to the rear plate 1. The first potential regulating electrode 6 is disposed on the surface of the plate-like spacer 3 in an area facing the faceplate 2. The plate-like spacer 3 is disposed between the x-direction wiring 4 and the anode 5 and between the x-direction wiring 4 and the first potential regulating electrode 6. The circuit 8 supplies the x-direction wiring 4, the anode 5, and the first potential regulating electrode 6 with an electric potential. The circuit 8 supplies the anode 5 with an electric potential (anode potential) that is higher than that supplied to the x-direction wiring 4 and the first potential regulating electrode 6. The electric potentials supplied to the x-direction wiring 4 and the first potential regulating electrode 6 may be different. However, it is desirable that the electric potentials are the same to simplify the configuration. To obtain useful luminance for field emission display apparatuses, the electric potential supplied to the anode 5 is preferably more than or equal to 5 kV, and more preferably more than or equal to 10 kV. In addition, if the electric potential supplied to the anode 5 is too high, the electric discharge easily occurs, although this depends on the distance between the rear plate 1 and the faceplate 2. Thus, practically, the electric potential supplied to the anode 5 is set to less than or equal to 30 kV. The practical electric potential supplied to the x-direction wiring 4 and the first potential regulating electrode 6 ranges from −100 V to 100 V. Typically, the electric potential is set to the ground potential. Note that the circuit 8 may be of any type that can supply electric potentials to the x-direction wiring 4, the anode 5, and the first potential regulating electrode 6. Accordingly, the circuit 8 is not limited to only one circuit. That is, the circuit 8 may include a circuit for supplying an electric potential to the x-direction wiring 4, a circuit for supplying an electric potential to the first potential regulating electrode 6, and a circuit for supplying an electric potential to the anode 5.
According to this exemplary embodiment of the present invention, in the image display apparatus, the x-direction wiring 4, the anode 5, and the first potential regulating electrode 6 can be in contact with the plate-like spacer 3 so as to supply the electric potential. At that time, the first region 21, the second region 22, and the third region 23 serve as a connection region with the anode 5 of the plate-like spacer 3, a connection region with the first potential regulating electrode 6 of the plate-like spacer 3, and a connection region with the x-direction wiring 4 of the plate-like spacer 3, respectively. In addition, when an electric potential is supplied from the anode 5, the first potential regulating electrode 6, and the x-direction wiring 4 to the plate-like spacer 3, a different member can be disposed between the plate-like spacer 3 and each of the anode 5, the first potential regulating electrode 6, and the x-direction wiring 4. At that time, the first region 21, the second region 22, and the third region 23 serve as a connection region between the anode 5 and the different member, a connection region between the first potential regulating electrode 6 and the different member, and a connection region between the x-direction wiring 4 and the different member, respectively.
The plate-like spacer 3 is disposed so that the longitudinal direction of the plate-like spacer 3 is substantially parallel to the x direction. Let Wx denote the width of the x-direction wiring 4 (in the y direction) and WSP denote the width of the plate-like spacer 3 (in the y direction). Then, the width WSP of the plate-like spacer 3 is preferably less than or equal to the width Wx of the x-direction wiring 4. Additionally, it is desirable that the plate-like spacer 3 is disposed in an area between the x-direction wiring 4 and the faceplate 2. The practical width Wx of the x-direction wiring 4 is greater than or equal to 50 μm and less than or equal to 500 μm.
According to this exemplary embodiment of the present invention, the following dimensions are suitable. The width WSP of the plate-like spacer 3 in the y direction is greater than or equal to 50 μm and less than or equal to 200 μm. A height H of the plate-like spacer 3 in the z direction is greater than or equal to 0.5 mm and less than or equal to 5 mm. In order to reduce electric discharge, a distance L12 between the first region 21 and the second region 22 can be greater than or equal to 1 mm, although this depends on the difference in electric potential between the anode 5 and the first potential regulating electrode 6. In addition, in order to reduce a peripheral region outside the anode 5 that does not contribute to displaying the image, the distance L12 is preferably less than or equal to 5 mm.
Here, let the sheet resistance of an area between the first region 21 and the second region 22 (i.e., the end surface of the plate-like spacer 3) be ρf [Ω/□]. That is, in
According to this exemplary embodiment of the present invention, the relationship between ρr and ρf is determined so that 1/100<ρr/ρf≦40. If this condition is satisfied, the electric field intensity applied to the end portion of the first potential regulating electrode 6 adjacent to the anode 5 can be sufficiently reduced. In addition, the electric field intensity applied to the end portion of the anode 5 adjacent to the first potential regulating electrode 6 can be reduced. Thus, the occurrence of electric discharge can be significantly reduced.
When the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is greater than 40, the equipotential lines between the first potential regulating electrode 6 and the anode 5 have substantially even spacing, as shown in
As shown in
When the sheet resistance ρr is significantly greater than the sheet resistance ρf, the electric potential at the point A is little effected by the electric potential of the third region 23, and therefore, the electric potential at the point A is determined primarily by the electric potentials of the first region 21 and the second region 22.
In contrast, when the sheet resistance ρr is less than or substantially equal to the sheet resistance ρf, the electric potential at the point A is strongly effected by the electric potential of the third region 23 in addition to the electric potentials of the first region 21 and the second region 22. Accordingly, the electric potential at the point A is decreased compared with the case where the sheet resistance ρr is significantly greater than the sheet resistance ρf.
From the above-described relationship, as the sheet resistance ratio ρr/ρf of the plate-like spacer 3 decreases, the electric potential of the plate-like spacer 3 around the first potential regulating electrode 6 decreases. Thus, the distance between the equipotential lines around the first potential regulating electrode 6 increases, and therefore, the electric field concentrated on the first potential regulating electrode 6 can be reduced.
A plurality of plate-like spacers 3 were produced so that the sheet resistance ρf of each of the plate-like spacers 3 was 1.0×10 [Ω/□], and the sheet resistance ρr was greater than or equal to 1.0×1011 [Ω/□] and less than or equal to 6.0×1012 [Ω/□]. When the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to a value less than or equal to 40, the electric field intensity of the first potential regulating electrode 6 is low. Thus, the occurrence of electric discharge around the first potential regulating electrode 6 can be significantly reduced. Accordingly, it is desirable that the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to a value less than or equal to 40.
As can be seen from the description above, it is desirable that the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is greater than 1/100 and is less than or equal to 40. Furthermore, by setting the sheet resistance ratio ρr/ρf of the plate-like spacer 3 to a value more than or equal to 3 and less than or equal to 10, an excellent image based on the emittance of the fluorescent member can be displayed without distortion at the edge thereof.
Additionally, when the sheet resistance ρf was set to a value greater than or equal to 1.0×107 [Ω/□] and less than or equal to 1.0×1014 [Ω/□] and the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was set to a value greater than 1/100 and less than or equal to 40, the electrical discharge was reliably prevented. Furthermore, when the sheet resistance ρr was set to a value greater than or equal to 1.0×107 [Ω/□] and less than or equal to 1.0×1014 [Ω/□] and the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was set to a value greater than 1/100 and less than or equal to 40, the electrical discharge was reliably prevented.
Still furthermore, when the sheet resistance ρf or the sheet resistance ρr was set to a value less than 1.0×107 [Ω/□], power consumption of the image display apparatus was increased. In contrast, when the sheet resistance ρf or the sheet resistance ρr was set to a value greater than 1.0×1014 [Ω/□], the electric discharge tended to occur over time during operation of the image display apparatus.
The plate-like spacer 3 according to the present exemplary embodiment is described next in detail.
The plate-like spacer 3 according to the present exemplary embodiment can have a variety of forms.
To obtain the sheet resistance ρf and the sheet resistance ρr of different values for the plate-like spacer 3 using an electroconductive material and having the shape shown in one of
A method for computing the sheet resistance ρf and the sheet resistance ρr of the plate-like spacer 3 using an electroconductive material (see
First, all regions except for the region 24 disposed between the first region 21 and the second region 22 and the third region 23 disposed between the region 24 and the third region 23 are cut off. That is, as shown in
Subsequently, an electrode 41 is connected to one end of the region 25 (a region corresponding to a resistive film 44 shown in
Alternatively, in
The sheet resistances ρr and ρf for the plate-like spacer 3 having a structure shown in one of
According to the present invention, examples of the structure of the plate-like spacer 3 further include the structure shown in
The plate-like spacer 3 having the structure shown in
The base 31 can be composed of a material having a mechanical strength that is sufficient to withstand atmospheric pressure applied to the rear plate 1 and the faceplate 2 of the image display apparatus. Examples of the material of the base 31 include a quartz glass, a glass having a low impurity content, such as Na, a soda lime glass, and a ceramic material, such as alumina.
To reduce electrostatic charge mainly caused by electrons impinging onto the side surface of the plate-like spacer 3, the resistive film 32 can have a sheet resistance that sufficiently reduces such electrostatic charge. Practically, the sheet resistance of the resistive film 32 disposed on the surface of the plate-like spacer 3 is preferably less than or equal to 1.0×1014 [Ω/□] and, more preferably, less than or equal to 1.0×1012 [Ω/□]. However, if the sheet resistance of the resistive film 32 coating the base 31 is low, power consumption of the image display apparatus increases due to an electric current flowing through the resistive film 32. Accordingly, it is desirable that the sheet resistance of the resistive film 32 disposed on the surface of the plate-like spacer 3 is greater than or equal to 1.0×107 [Ω/□]. Examples of a material for the resistive film 32 include a metal oxide (such as chrome oxide, nickel oxide, and copper oxide), aluminum-transition metal nitride, germanium-transition metal nitride, and a carbon (such as amorphous carbon). Examples of a transition metal element include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, W, Hf, and Ta. Such a transition metal in the nitride may be used by itself, or at least two types of transition metal element may be used together.
Examples of a method for forming the resistive film 32 on the base 31 include a vapor-phase deposition method (such as sputtering, electron beam evaporation, ion plating, ion assist evaporation, CVD, or plasma CVD) and a liquid-phase deposition method (such as spraying or dipping).
To achieve a structure of the plate-like spacer 3 in which the sheet resistance ρf is different from the sheet resistance ρr, the plate-like spacer 3 is formed in the following way, for example.
First, a material of the resistive film 32 is coated over the entire surface of the base 31 so that the desired highest sheet resistance is obtained by adjusting the duration of deposition of the resistive film 32 on the base 31. Subsequently, the material of the resistive film 32 is further deposited only on areas of the resistive film 32 whose sheet resistance is desired to be decreased so that the desired sheet resistance can be obtained by adjusting the duration of deposition. That is, according to this method, by adjusting the duration of deposition of the material of the resistive film 32, the thickness of the formed resistive film 32 can be changed, and therefore, the sheet resistance of the resistive film 32 can be controlled. Alternatively, by depositing different materials of the resistive film 32 on an area whose sheet resistance is desired to be increased and an area whose sheet resistance is desired to be decreased, the sheet resistance of the resistive film 32 can be controlled.
A method for computing the sheet resistance ρf and the sheet resistance ρr of the plate-like spacer 3 in which the base 31 is coated with the resistive film 32 (see
First, the entire region of the resistive film except for a predetermined region is removed by etching. That is, the region of the resistive film not to be removed is the region 24 located between the first region 21 and the second region 22. Hereinafter, this resistive film is referred to as a “resistive film 45”. In addition, a resistive film in the region 25 located between the third region 23 and the region 24 located between the first region 21 and the second region 22 is not removed. Hereinafter, this resistive film is referred to as a “resistive film 44”. The insulating base 31 is exposed through the areas where the resistive films of the plate-like spacer 3 are removed.
Subsequently, as shown in
Alternatively, as shown in
The whole structure of the image display apparatus according to the present embodiment is described next with reference to
The y-direction wiring 51 is disposed on the rear plate 1 so as to extend in a direction perpendicular to the x-direction wiring 4. The x-direction wiring 4 can be disposed so as to intersect the y-direction wiring 51. In this case, the x-direction wiring 4 is disposed above the y-direction wiring 51 with an insulating layer (not shown) therebetween at the intersection between the x-direction wiring 4 and the y-direction wiring 51.
The y-direction wiring 51 may be disposed in a groove formed on the surface of the rear plate 1. Alternatively, the y-direction wiring 51 and the insulating layer (not shown) located between the y-direction wiring 51 and the x-direction wiring 4 at the intersection thereof may be disposed in a groove formed on the surface of the rear plate 1. In this case, the y-direction wiring 51 and the insulating layer are disposed in the groove formed on the surface of the rear plate 1 and the x-direction wiring 4 is disposed so as to intersect with the y-direction wiring 51. In this way, the x-direction wiring 4 is disposed on a surface that is substantially flat. Accordingly, the plate-like spacer 3 can be reliably connected to the x-direction wiring 4.
The circuit 8 amplifies or decreases the electric potential supplied from a power supply unit, such as a power outlet at home or a battery, disposed outside the image display apparatus so as to convert the electric potential to a predetermined electric potential. The circuit 8 includes, for example, a transformer, a coil, a resistor, and a wiring.
The circuit 8 supplies an electric potential that is lower than that of the anode 5 to the x-direction wiring 4 and the y-direction wiring 51. Practically, an electric potential in the range from −100 V to 100 V is applied to the x-direction wiring 4 and the y-direction wiring 51.
Each of a plurality of the plate-like spacers 3 in the image display apparatus is disposed on the corresponding one of the x-direction wirings 4 so that the longitudinal direction of each of the plate-like spacers 3 is substantially parallel to the x direction. The plate-like spacers 3 may be disposed on every other x-direction wiring 4 or on every few x-direction wirings 4. That is, for example, the plate-like spacers 3 may be disposed on the odd-numbered (even-numbered) x-direction wirings 4. Alternatively, n x-direction wirings 4 may be disposed between two adjacent x-direction wirings 4 on which the plate-like spacers 3 are disposed, where n≧2.
An electroconductive material can be used for the first potential regulating electrode 6 provided on the plate-like spacer 3. It is desirable that the electroconductive material is a metal, such as Al or Cu.
The electric potential of the first potential regulating electrode 6 is supplied from the circuit 8. In addition, a wiring (not shown) can be provided on the plate-like spacer 3 so that the first potential regulating electrode 6 is connected to the x-direction wiring 4. This wiring can be disposed, for example, at the end of the plate-like spacer 3 in the x direction. Furthermore, this wiring can be disposed in the region located between the second region 22 and the third region 23. This arrangement of the wiring allows the electric potential of the x-direction wiring 4 to be supplied to the first potential regulating electrode 6. Still furthermore, this wiring may be integrated into the first potential regulating electrode 6.
Each of a plurality of the electron emitting devices 52 is connected to any one of the x-direction wirings 4 and is connected to any one of the y-direction wirings 51.
According to the present invention, a typical example of the electron emitting device 52 is a surface conduction electron emitting device. However, the present invention is not limited thereto. For example, an MIM electron emitting device, an MIS electron emitting device, or a field electron emitting device may be used for the electron emitting device 52. A typical example of the field electron emitting device is an electron emitting device known as a Spindt-type electron emitting device including an electron emitter formed by microfabricating a metal or a semiconductor into a cone shape or a quadrangular pyramid shape. Alternatively, a field electron emitting device may include a carbon fiber having a nano-scale diameter, such as a carbon nanotube or a graphite nanofiber, serving as the electron emitter.
In the image display apparatus according to the present invention, the circuit 8 supplies an electric potential to the x-direction wiring 4 and the y-direction wiring 51 so that the electron emitting device 52 connected to the x-direction wiring 4 and the y-direction wiring 51 emits electrons. The emitted electrons are accelerated towards the anode 5 to which the circuit 8 supplies an electric potential higher than that for the x-direction wiring 4 and the y-direction wiring 51.
The faceplate 2 included in the image display apparatus according to the present invention is described next with reference to
The length in the longitudinal direction of the plate-like spacer 3 can be longer than that of the anode 5 in the same direction. In the image display apparatus shown in
The faceplate 2 can be composed of a glass. The fluorescent member 7 and the anode 5 are disposed on the surface of the faceplate 2 adjacent to the rear plate 1.
An anode potential Va is applied to the anode 5 in order to accelerate the electrons emitted from the electron emitting device 52.
Any material that emits light when irradiated with an electron beam can be used for the fluorescent member 7. In general, a fluorescent member that can be used for a cathode-ray tube (CRT) is used for the fluorescent member 7.
In the image display apparatus according to the present invention, the anode 5 can be disposed so as to cover the fluorescent member 7 disposed on the surface of the faceplate 2.
In such a case, a metallic film (e.g., an aluminum film) can be used for the material of the anode 5.
In order to maintain a pressure inside the envelope 10 formed from the rear plate 1, the side wall 9, and the faceplate 2, a film formed from a getter material, such as Ba or Ti, is preferably provided on the metallic film. In such a case, the anode 5 includes the metallic film and the getter film.
In addition, to increase the contrast of a displayed image, an electroconductive black member having a plurality of openings (a black matrix) (not shown) may be disposed on the faceplate 2. Each of the openings corresponds to a pixel of R, G, or B. The corresponding fluorescent member is disposed in each opening. A low-melting glass containing carbon black or a black pigment can be used for the material of the black member. In such a case, the anode 5 includes the black member and the metallic film in the case of not disposing the getter film and includes the black member, the metallic film, and the getter film in the case of disposing the getter film.
In contrast, when the conductive black member having the plurality of openings is disposed on the faceplate 2, a light-transmissive electroconductive film may be disposed between the black member and the faceplate 2 in place of the metallic film. An ITO or a tin oxide can be used for the material of the light-transmissive electroconductive film. In such a case, the anode 5 includes the black member and the light-transmissive electroconductive film.
In addition, a video signal receiving and display apparatus can be provided using the image display apparatus according to the present invention illustrated with reference to, for example,
According to the image display apparatus of the present exemplary embodiment, the electric field concentrated on the first potential regulating electrode 6 can be reduced, and therefore, the image display apparatus that can reduce the occurrence of electric discharge can be achieved.
An image display apparatus according to a second exemplary embodiment is described next with reference to
The circuit 8 supplies the second potential regulating electrode 71 with an electric potential that is lower than that of the anode 5. The electric potential supplied to the second potential regulating electrode 71 is preferably the same as that supplied to the first potential regulating electrode 6. The second potential regulating electrode 71 then supplies an electric potential to the plate-like spacer 3. For example, the second potential regulating electrode 71 may be the y-direction wiring 51 shown in
Here, let a plane that passes through the end of the anode 5 adjacent to the first potential regulating electrode 6 and whose normal direction is a direction in which the anode 5 faces the first potential regulating electrode 6 denote a “first plane”. Let a plane that passes through the end of the first potential regulating electrode 6 adjacent to the anode 5 and whose normal direction is the direction in which the anode 5 faces the first potential regulating electrode 6 denote a “second plane”. In the present exemplary embodiment, the second potential regulating electrode 71 is disposed so that at least part of the plate-like spacer 3 is located between the first plane and the second plane and, in addition, the first plane and the second plane pass through the third region 81. A length W1 of the third region 81 in the x direction is greater than or equal to the distance L12 between the first region 21 and the second region 22. In addition, the length of the third region 81 in the y direction is greater than or equal to the length of the plate-like spacer 3 in the y direction.
Subsequently, the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is determined so that 1/100<ρr/ρf≦40. In this way, the electric field intensity applied to the first potential regulating electrode 6 can be decreased. In addition, the electric field concentrated on the end of the anode 5 adjacent to the first potential regulating electrode 6 can be decreased, and therefore, the occurrence of electric discharge can be reduced.
According to the second exemplary embodiment, the electric field concentrated on the first potential regulating electrode 6 can be decreased, and therefore, the image display apparatus that can reduce the occurrence of electric discharge can be achieved.
An image display apparatus according to a third exemplary embodiment is described next with reference to
In the first exemplary embodiment, the first potential regulating electrode 6 is disposed on the plate-like spacer 3, and an electric potential that is lower than that of the anode 5 is supplied to the first potential regulating electrode 6. However, if the anode potential applied to the anode 5 is increased, the intensity of electric field applied to the corner of the end of the plate-like spacer 3 in the longitudinal direction (the x direction) and the structure, such as a securing member for securing the plate-like spacer 3 increases. Thus, a different method for reducing electric discharge may be needed.
In the third exemplary embodiment, the third potential regulating electrode 91 is disposed between the faceplate 2 and the first potential regulating electrode 6. The circuit 8 supplies the third potential regulating electrode 91 with an electric potential that is lower than that of the anode 5. Accordingly, furthermore, the electric field concentration on the corner of the plate-like spacer 3 and the structure can be reduced. The third potential regulating electrode 91 may be disposed so as to be separated from the first potential regulating electrode 6 without contacting the first potential regulating electrode 6. However, if the third potential regulating electrode 91 is in contact with the first potential regulating electrode 6, furthermore, the electric field concentration on the corner of the plate-like spacer 3 and the structure can be reduced. In addition, if the third potential regulating electrode 91 is in contact with the first potential regulating electrode 6, an electric potential can be supplied from the first potential regulating electrode 6 to the third potential regulating electrode 91.
The electric potential supplied to the third potential regulating electrode 91 is preferably the same as that supplied to the first potential regulating electrode 6 and the x-direction wiring 4. The practical electric potential supplied to the third potential regulating electrode 91 ranges from −100 V to 100 V.
The faceplate 2 of the image display apparatus according to the third exemplary embodiment is described next with reference to
The circuit 8 supplies an electric potential to at least part of the anode 5 shown in the plan view of
In a practical point of view, the distance between the anode 5 and the third potential regulating electrode 91 is greater than or equal to 1 mm in order to reduce the electric discharge and is less than or equal to 5 mm in order to reduce the space outside the anode 5. To form the third potential regulating electrode 91, a photolithographic method using a photosensitive material or a screen printing method using a paste containing an electroconductive material can be used.
To form the third potential regulating electrode 91, a metal (such as a silver or a copper), an electroconductive material including metal particles and a low-melting glass, or conductive carbon black can be used for the material of the third potential regulating electrode 91.
In the image display apparatus according to the third exemplary embodiment, the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is determined so that 1/100<ρr/ρf≦40. Thus, the electric field intensity applied to the first potential regulating electrode 6 can be decreased. In addition, the electric field concentrated on the end of the anode 5 adjacent to the first potential regulating electrode 6 can be decreased, and therefore, the occurrence of electric discharge can be reduced.
According to the third exemplary embodiment, the electric field concentrated on the first potential regulating electrode 6 and the third potential regulating electrode 91 can be decreased, and therefore, the image display apparatus that can reduce the occurrence of electric discharge can be achieved.
An image display apparatus according to a fourth exemplary embodiment is described next with reference to
In the image display apparatus according to the fourth exemplary embodiment, as shown in
According to the fourth embodiment, the faceplate 2 of the image display apparatus can have the structure shown in the plan view of
Subsequently, the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is determined so that 1/100<ρr/ρf≦40. Thus, the electric field intensity applied to the first potential regulating electrode 6 can be decreased. In addition, the electric field concentrated on the end of the anode 5 adjacent to the first potential regulating electrode 6 can be decreased, and therefore, the occurrence of electric discharge can be reduced.
When the first potential regulating electrode 6 is fabricated by screen printing, an applied paste may be dragged down by its own weight. Accordingly, after the first potential regulating electrode 6 is fired, the surface of the first potential regulating electrode 6 adjacent to the rear plate 1 may be rounded.
In addition, since the resistance of the first potential regulating electrode 6 is low, the potential over the entire first potential regulating electrode 6 is uniform. However, the potential on the plate-like spacer 3 at a point distant from the second region 22 (e.g., a point B shown in
Even in such a case, by setting the sheet resistance ratio ρr/ρf of the plate-like spacer 3 so that 1/100<ρr/ρf≦40, the electric field intensity around the second region 22 can be decreased. In addition, since the distance between the equipotential lines around the second region 22 increases in an area between the first region 21 and the second region 22, the intensity of the electric field applied to the end of the first potential regulating electrode 6 adjacent to the anode 5 can be reduced. Furthermore, the electric field concentrated on the end of the anode 5 adjacent to the first potential regulating electrode 6 can be decreased, and therefore, the occurrence of electric discharge can be reduced.
According to the fourth exemplary embodiment, the image display apparatus that can reduce the electric field concentrated on the first potential regulating electrode 6 and the occurrence of electric discharge can be achieved.
In the fourth exemplary embodiment, any material having electrical conductivity can be used for the electrode and the wiring. Accordingly, the electrode may function as the wiring.
While the present invention has been described with reference to an image display apparatus having the envelope 10 including the rear plate 1, the faceplate 2, and the side wall 9, the structure of the image display apparatus is not limited thereto. For example, the envelope 10 may include a dish-shaped rear plate 1 and the faceplate 2 or may include the rear plate 1 and a dish-shaped faceplate 2.
The embodiments described above are merely illustrative in nature and are in no way intended to limit the invention. The components in the exemplary embodiments described above can be replaced with any alternatives and equivalents within the spirit and scope of the invention.
The present invention is described in detail below with reference to specific examples.
In this example, fifteen image display apparatuses having the structure shown in
The structure of the image display apparatuses according to EXAMPLE 1 is described below.
(1) The anode 5 and the fluorescent member 7 were formed on the faceplate 2.
A transparent substrate composed of a glass was used as the faceplate 2. A conductive black member having openings in which fluorescent members were disposed was formed on the glass by photolithography. Electroconductive photosensitive carbon black was used as a material of the conductive black member. The thickness of the conductive black member was set to 10 μm. A fluorescent member of an R, G, or B color serving as the fluorescent member 7 was disposed in each of the openings of the conductive black member. Each of the fluorescent members of R, G, and B colors was fabricated in the corresponding opening of the conductive black member so as to have a thickness of 10 μm by screen printing. A 100 nm-thickness Al film was deposited on the entire surfaces of the conductive black member and the fluorescent members by vapor deposition. Thus, the anode 5 including the conductive black member and the Al film was formed.
(2) The plate-like spacer 3 was formed.
In this example, the plate-like spacer 3 having the cross section shown in
TABLE 1 shows the result of measurement of the sheet resistances ρf and ρr of the plate-like spacer 3 of each of Samples 1 to 15. Note that the fabricated plate-like spacer 3 was 1.6 mm in height (H) and 200 μm in width (Wsp).
(3) The first potential regulating electrode 6 was formed on the plate-like spacer 3.
Al was deposited on the plate-like spacer 3 at a position separated from the first region 21 and facing the faceplate 2 by sputtering. Thus, the first potential regulating electrode 6 was formed. The first potential regulating electrode 6 was formed so that the distance L12 between the first region 21 and the second region 22 is 2 mm. The thickness of the first potential regulating electrode 6 in the z direction was set to 2 μm.
(4) A wiring and an electron emitting device were formed on the rear plate 1.
A glass substrate was prepared for the rear plate 1. One hundred y-direction wirings 51 composed of Ag were formed on the glass substrate with a spacing of 500 μm therebetween by printing. The y-direction wiring 51 is 100 μm in width and 10 μm in thickness. Subsequently, insulating layers (not shown) composed of a silicon oxide and PbO were formed on the intersections between the x-direction wiring 4 and the y-direction wirings 51 by printing. The thickness of the insulating layers was set to 10 μm. Thereafter, three hundred x-direction wirings 4 were formed, by printing, with a spacing of 200 μm therebetween so as to intersect the y-direction wirings 51. The x-direction wiring 4 is 300 μm in width (Wxw) and 10 μm in thickness. A plurality of the surface-conduction electron emitting devices 52 were formed using a known fabricating method so that any one of the x-direction wirings 4 was connected to any one of the y-direction wirings 51.
(5) The above-described plate-like spacer 3 was disposed on each of the x-direction wirings 4 formed on the rear plate 1.
(6) The side wall 9 was connected to the rear plate 1 and the faceplate 2.
The side wall 9 was disposed between the rear plate 1 and the faceplate 2. The side wall 9 was then bonded to the rear plate 1 by an adhesive agent and the side wall 9 was bonded to the faceplate 2 by an adhesive agent. Thus, the image display apparatus shown in
Subsequently, the evaluation of electric discharge in the image display apparatus fabricated in this way was performed as follows.
The x-direction wiring 4, the y-direction wiring 51, and the first potential regulating electrode 6 were set to the GND potential. A gradually increasing anode potential was applied to the anode 5. At that time, an electrical current flowing between the anode 5 and the first potential regulating electrode 6 and an electrical current flowing between the anode 5 and the x-direction wiring 4 were measured. The anode potential was increased in steps of 1 kV. When the sum of the electrical current flowing between the anode 5 and the first potential regulating electrode 6 and the electrical current flowing between the anode 5 and the x-direction wiring 4 reaches a value greater than or equal to 1 mA, the value of the anode potential was recorded. This anode potential was considered to be a potential when electrical discharge occurred.
TABLE 1 shows the anode potentials measured using the above-described method when electrical discharge occurs.
In this example, Samples 3 to 7 reduce the occurrence of electric discharge more than Samples 1, 2, 8, and 9. Additionally, Samples 10 to 15 can reduce the occurrence of electric discharge. That is, when the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1/100<ρr/ρf≦40, the occurrence of electrical discharge can be reduced. When the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1<ρr/ρf≦40, the occurrence of electrical discharge can be further reduced. Furthermore, by setting the sheet resistance ratio ρr/ρf of the plate-like spacer 3 so that 3≦ρr/ρf≦10, the occurrence of electrical discharge can be efficiently reduced, and therefore, an excellent image can be displayed without distortion at the edge thereof.
In addition, the withstand voltage of the sample that can reduce the occurrence of electrical discharge satisfies the condition: the anode potential (Va)≧10 kV, which is required for obtaining useful luminance of field emission displays.
Additionally, when the sheet resistances ρf and ρr of the plate-like spacer 3 are greater than or equal to 1.0×107 [Ω/□] and less than or equal to 1.0×1014 [Ω/□] and the sheet resistance ratio ρr/ρf is kept constant, the anode potentials when electrical discharge occurs are substantially the same.
In addition, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was the same as those of Samples 3 to 7 and Samples 10 to 15 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 was less than 1.0×107 [Ω/□]. When an image is displayed on these samples, power consumption is increased compared with Samples 3 to 7 and Samples 10 to 15. Furthermore, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was the same as those of Samples 3 to 7 and Samples 10 to 15 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 was greater than 1.0×1014 [Ω/□]. When electric discharge of these samples is evaluated while applying the same anode potential, electric discharge occurs in a short time compared with Samples 3 to 7 and Samples 10 to 15.
In this example, seven image display apparatuses having the structure shown in
The primary structures of the image display apparatuses in this example are similar to those of Example 1. Accordingly, only differences between Example 2 and Example 1 are described.
In this example, the length of the third region 81 in the x direction was set to 2 mm and the length of the third region 81 in the y direction was set to 200 mm.
Subsequently, like Example 1, electric discharge of the image display apparatuses in this example was evaluated. The anode potentials when electric discharge occurred are shown in Table 2.
In this example, Samples 2 to 6 can reduce the occurrence of electric discharge more than Samples 1 and 7. That is, when the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1/100<ρr/ρf≦40, the occurrence of electrical discharge can be reduced. When the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1<ρr/ρf≦40, the occurrence of electrical discharge can be further reduced.
Like Example 1, when the sheet resistances ρf and ρr of the plate-like spacer 3 are greater than or equal to 1.0×107 [Ω/□] and less than or equal to 1.0×1014 [Ω/□] and the sheet resistance ratio ρr/ρf is kept constant, the anode potentials when electrical discharge occurs are substantially the same. Furthermore, by setting the sheet resistance ratio ρr/ρf of the plate-like spacer 3 to a value more than or equal to 3 and less than or equal to 10, the occurrence of electrical discharge can be efficiently reduced, and therefore, an excellent image can be displayed without distortion at the edge thereof.
In addition, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is the same as those of Samples 2 to 6 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 is less than 1.0×107 [Ω/□]. When an image is displayed on these samples, power consumption is increased compared with Samples 2 to 6. Furthermore, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is the same as those of Samples 2 to 6 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 is greater than 1.0×1014 [Ω/□]. When electric discharge of these samples is evaluated while applying the same anode potential, electric discharge occurs in a short time compared with Samples 2 to 6.
In this example, seven image display apparatuses having the structure shown in
The primary structures of the image display apparatuses in this example are similar to those of Example 1. Accordingly, only differences between Example 3 and Example 1 are described.
In this example, the third potential regulating electrode 91 was formed on the faceplate 2 at a position separated from the anode 5 and facing the first potential regulating electrode 6.
The third potential regulating electrode 91 was formed on the faceplate 2 using carbon black. The distance between the third potential regulating electrode 91 and the anode 5 was set to 2 mm. The thickness of the third potential regulating electrode 91 in the z direction was set to 5 μm. The width of a region of the third potential regulating electrode 91 over which the plate-like spacer 3 extended in the x direction was set to 500 μm.
Subsequently, like Example 1, electric discharge of the image display apparatuses in this example was evaluated. However, the third potential regulating electrode 91 was set to the GND potential. Electric currents flowing between the first potential regulating electrode 6 and the anode 5 and between the third potential regulating electrode 91 and the anode 5 were measured rather than measuring an electrical current flowing between the first potential regulating electrode 6 and the anode 5. The anode potentials when electric discharge occurred are shown in Table 3.
In this example, Samples 2 to 6 reduce the occurrence of electric discharge more than Samples 1 and 7. That is, when the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1/100<ρr/ρf≦40, the occurrence of electric discharge can be reduced. When the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1<ρr/ρf≦40, the occurrence of electrical discharge can be further reduced.
Additionally, like Example 1, when the sheet resistances ρf and ρr of the plate-like spacer 3 are greater than or equal to 1.0×107 [Ω/□] and less than or equal to 1.0×1014 [Ω/□] and the sheet resistance ratio ρr/ρf is kept constant, the anode potentials when electrical discharge occurs are substantially the same. Furthermore, by setting the sheet resistance ratio ρr/ρf of the plate-like spacer 3 to a value more than or equal to 3 and less than or equal to 10, the occurrence of electrical discharge can be efficiently reduced, and therefore, an excellent image can be displayed without distortion at the edge thereof.
In addition, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was the same as those of Samples 2 to 6 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 was less than 1.0×107 [Ω/□]. When an image is displayed on these samples, power consumption is increased compared with Samples 2 to 6. Furthermore, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was the same as those of Samples 2 to 6 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 was greater than 1.0×1014 [Ω/□]. When electric discharge of these samples is evaluated while applying the same anode potential, electric discharge occurs in a short time compared with Samples 2 to 6.
In this example, seven image display apparatuses having the structure shown in
The structures of the image display apparatuses in this example are similar to those of Example 1 except that the first potential regulating electrode 6 was disposed so as to be in contact with the faceplate 2. Accordingly, only differences between Example 4 and Example 1 are described.
In this example, the first potential regulating electrode 6 was formed so as to be in contact with the faceplate 2.
The first potential regulating electrode 6 was formed on the faceplate 2 using carbon black. The distance between the first region 21 and the second region 22 was set to 2 mm. The thickness of the first potential regulating electrode 6 in the z direction was set to 10.1 μm. After the withstand voltage had been evaluated, the faceplate 2 was removed and checked. At that time, it was found that a region of the surface of the faceplate 2 adjacent to the rear plate 1 at a position at which the faceplate 2 was in contact with the first potential regulating electrode 6 slightly caved in. Thus, it is confirmed that the surface of the faceplate 2 adjacent to the rear plate 1 is in contact with the first potential regulating electrode 6.
Subsequently, like Example 1, electric discharge of the image display apparatuses in this example was evaluated. The evaluation was performed as in Example 1. The anode potentials when electric discharge occurred are shown in Table 4.
In this example, Samples 2 to 6 can reduce the occurrence of electric discharge more than Samples 1 and 7. That is, when the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1/100<ρr/ρf≦40, the occurrence of electrical discharge can be reduced. When the sheet resistance ratio ρr/ρf of the plate-like spacer 3 is set to be 1<ρr/ρf≦40, the occurrence of electrical discharge can be reduced. Furthermore, by setting the sheet resistance ratio ρr/ρf of the plate-like spacer 3 so that 3≦ρr/ρf≦10, the occurrence of electrical discharge can be efficiently reduced, and therefore, an excellent image can be displayed without distortion at the edge thereof.
Additionally, like Example 1, when the sheet resistances ρf and ρr of the plate-like spacer 3 are greater than or equal to 1.0×107 [Ω/□] and less than or equal to 1.0×1014 [Ω/□] and the sheet resistance ratio ρr/ρf is kept constant, the anode potentials when electrical discharge occurs are substantially the same.
In addition, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was the same as those of Samples 2 to 6 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 was less than 1.0×107 [Ω/□]. When an image is displayed on these samples, power consumption is increased compared with Samples 2 to 6. Furthermore, samples were fabricated in which the sheet resistance ratio ρr/ρf of the plate-like spacer 3 was the same as those of Samples 2 to 6 and at least one of the sheet resistances ρf and ρr of the plate-like spacer 3 was greater than 1.0×1014 [Ω/□]. When electric discharge of these samples is evaluated while applying the same anode potential, electric discharge occurs in a short time compared with Samples 2 to 6.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions.
This application claims the benefit of Japanese Application No. 2006-008812 filed Jan. 17, 2006, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-008812 | Jan 2006 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6803717 | Ohnishi | Oct 2004 | B2 |
| 6998769 | Ohnishi | Feb 2006 | B2 |
| 7247981 | Yamazaki | Jul 2007 | B2 |
| 7391149 | Yamazaki | Jun 2008 | B2 |
| Number | Date | Country |
|---|---|---|
| 2002-237268 | Aug 2002 | JP |
| 2002-367540 | Dec 2002 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20070164674 A1 | Jul 2007 | US |
