Patent Grant
8227973
1. Field of the Invention
The present invention relates to a display panel that performs display by accelerating electrons and causing the electrons to collide with light-emitting members.
2. Description of the Related Art
A flat display panel using cathode luminescense includes a rear plate and a face plate that are disposed so as to face each other. The rear plate has electron-emitting devices and wiring, and the face plate has light-emitting members such as phosphors and an anode. The space between the rear plate and the face plate is maintained as a vacuum.
The electron-emitting devices driven via the wiring emit electrons. A high potential relative to a ground potential, ranging from a few kV to a few tens of kV, is externally applied to the anode through an anode terminal. The emitted electrons are accelerated by this potential and collide with the light-emitting members, thereby causing the light-emitting members to emit light. Display can be performed using this light emission (cathode luminescense).
At the same time, since the anode terminal is set to a high potential, unintended discharge (abnormal discharge) may occur near the anode terminal.
Japanese Patent Laid-Open No. 2006-222093 discloses an electron beam device that suppresses abnormal discharge by providing independent wiring near a potential supplying path.
According to an aspect of the present invention, a display panel includes an insulating substrate, wiring connected to an electron-emitting devices on the substrate, an anode and light-emitting members facing the electron-emitting device, a terminal that penetrates through the substrate and is connected to the anode, and a conductive member whose portion is positioned in a region between the wiring and the terminal, the conductive member being provided on the substrate so as to surround the terminal. The terminal is set to an anode potential, and the conductive member is set to a potential lower than the anode potential. The conductive member includes, at an inner edge thereof, a plurality of portions whose distances from the terminal are different, and the plurality of portions include a portion whose distance from the terminal is shorter than that of a portion among the plurality of portions that is closest to the wiring.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, an embodiment of the present invention will be described using
The display apparatus at least includes a display panel 1000, an anode-potential setting unit 20, a prescribed-potential setting unit 21, and a drive circuit.
The display panel 1000 will now be described. The display panel 1000 includes a rear plate 100 and a face plate 200 that are disposed so as to face each other. The space (inner space 300) between the rear plate 100 and the face plate 200 is a vacuum (pressure lower than the atmospheric pressure). Specifically, the inner space 300 is maintained as a vacuum by using a hermetical-sealed container including the real plate 100, the face plate 200, and a frame member 9. In other words, the display panel 1000 is also a hermetically-sealed container (vacuum container) in which the inner space 300 is maintained as a vacuum.
The rear plate 100 at least includes the first substrate 1, which is an insulating substrate, electron-emitting devices 11 provided on the surface 101 of the first substrate 1, and wiring 13. In
In the embodiment of the present invention, an “insulating” member is a member whose volume resistivity is greater than that of a “conductive” member. Practically, a member made of a material having a volume resistivity of 106 Ωm or greater is preferably used as an “insulating” member. Also, a member made of a material having a volume resistivity of 10−3 Ωm or less is preferably used as a “conductive” member. More preferably, a member made of a material having a volume resistivity of 10−5 Ωm or less is used as a “conductive” member. Note that “wiring”, “electrodes”, and “terminals” are conductive members. Hereinafter, a “potential” is described as a value based on the ground potential serving as a reference potential (0 V).
Typically, many, such as a million or more electron-emitting devices 11 are arranged in a matrix. Each of the electron-emitting devices 11 at least includes a cathode, and, if necessary, a gate that controls emission of electrons from the cathode.
The wiring 13 is connected to the electron-emitting devices 11 in the inner space 300. Also, the wiring 13 extends toward the edge of the first substrate 1 and extracted to the outer space. When many electron-emitting devices 11 are arranged in a matrix, matrix wiring including multiple column wirings 131 extending in the column direction (Y-direction) and multiple row wirings 132 extending in the row direction (X-direction) are typically used as the wiring 13. In the matrix wiring, the column wirings 131 and the row wirings 132 intersect each other with an insulating layer (not illustrated) being provided therebetween. Here, it is illustrated that, at the intersection of one column wiring 131 and one row wiring 132, the column wiring 131, the insulating layer, and the row wiring 132 are stacked on the first substrate 1 in this order. That is, the column wiring 131 serves as a lower line, and the row wiring 132 serves as an upper line.
The drive circuit is a circuit for driving the electron-emitting devices 11, that is, for causing electrons to be emitted. The drive circuit is an electric circuit that at least includes the cathode-potential setting unit 22 and, if necessary, a gate-potential setting unit 23. As illustrated in
The face plate 200 at least includes a second substrate 2, which is an insulating substrate that is transparent, i.e., that has transparency to light, and an anode 8 provided on a surface 201 of the second substrate 2. The surface 201 of the second substrate 2 is the surface of the second substrate 2, facing the inner space 300.
The anode 8 is a conductive member that is shaped as a film, a layer, or a plate. For example, a metal thin film called “metal back” may be used to form the anode 8. Preferably, aluminum is used as a metal of the metal back. Alternatively, a transparent conductive material such as ITO or ZnO may be used as the anode 8.
The face plate 200 further includes light-emitting members 12, such as fluorescent materials or phosphors, on the surface 201 of the second substrate 2. When a metal back is used as the anode 8, the light-emitting members 12 are provided between the metal back and the second substrate 2. When a transparent conductive material is used as the anode 8, the anode 8 may be provided between the second substrate 2 and the light-emitting members 12. In either case, the anode 8 is provided on the surface 201 of the second substrate 2.
If necessary, the display panel 1000 includes a guard electrode 6 and a connection electrode 7 on the surface 201 of the second substrate 2.
As described above, the display panel 1000 has a structure in which the anode 8 and the light-emitting members 12 of the face plate 200 are disposed so as to face, at a distance, the electron-emitting devices 11 of the rear plate 100. With this structure, a display region can be formed. The display region is a region in which, on the face plate 200, the light-emitting members 12 are provided, and, on the rear plate 100, the electron-emitting devices 11 are provided. In other words, a region where the electron-emitting devices 11 face the light-emitting devices 12 is regarded as a display region.
An anode terminal 4 penetrates through the first substrate 1 and is electrically connected to the anode 8 in the inner space 300. The anode terminal 4 is connected to the anode-potential setting unit 20 in the outer space and is set to an anode potential Va. The anode potential Va is a potential that is higher than the cathode potential Vc and is higher than the gate potential Vg.
In the embodiment of the present invention, members are “electrically connected” when the members are mechanically connected to each other directly or via a conductive member and are thus electrically conductive. Members are “mechanically connected” when the members are adhered or joined to each other or abut on each other, or when the members are in contact with each other.
A portion surrounded by a one-dot chain ellipse in
The anode terminal 4 is typically a conductive member such as a metal pin or a metal spring. As illustrated in
The anode 8 is electrically connected to the anode terminal 4 via the connection electrode 7. Here, the structure is illustrated in which the anode 8 is electrically connected to the connection electrode 7, and the connection electrode 7 is electrically connected to the anode terminal 4. However, the anode 8 and the anode terminal 4 may be directly and electrically connected to each other without providing the connection electrode 7 therebetween.
Specifically, at the lead-in 10, the anode terminal 4 goes through a through hole 10a provided in the first substrate 1. In this manner, the anode terminal 4 penetrates through the first substrate 1. At the lead-in 10, the through hole 10a is filled up using a sealing member 10b in order to maintain the inner space 300 of the display panel 1000 as a vacuum. Though not illustrated, an auxiliary member that helps connection of the anode terminal 4 to the connection electrode 7 or that helps fixing of the anode terminal 4 to the first substrate 1 may be provided near the lead-in 10. When the auxiliary member and the sealing member 10b are conductive and when these members are electrically connected to the anode terminal 4 illustrated in
The anode 8 is set to the anode potential Va or a potential that is substantially equal to the anode potential Va via the anode terminal 4 and the connection electrode 7. Electrons emitted from the electron-emitting devices 11 are accelerated by the anode potential Va and collide with the light-emitting members 12. As above, the display apparatus according to the embodiment of the present invention is an electron beam device that accelerates electrons emitted from the electron-emitting devices 11 using an electric field formed by the anode 8.
The light-emitting members 12 emit light as a result of collision of electrons. The practical anode potential Va necessary for causing the light-emitting members 12 to emit light is within the range from 1 kV to 100 kV, preferably within the range from 5 kV to 30 kV, and more preferably within the range from 10 kV to 25 kV.
As illustrated in
In
For the conductive member 3, a material whose volume resistivity is 10−3 Ωm or less may be used, or a material whose volume resistivity is 10−5 Ωm or less may preferably be used. As a material suitable for the conductive member 3, a metal such as Cu, Ag, Au, Al, Ti, or Pt, or an alloy or a metallic compound including these metals may be used. As a method for forming the conductive member 3, the conductive member 3 may be formed by preparing a member that is shaped as the conductive member 3 beforehand and arranging this member on the surface 101 of the first substrate 1. However, the thickness of the conductive member 3 is preferably thin in order to suppress discharge between the conductive member 3 and at least one of the anode 8 and the connection electrode 7. Practically, the thickness of the conductive member 3 is 100 μm or less. Therefore, the conductive member 3 is preferably formed as a conductive film on the surface 101 of the first substrate 1 by using a known method, such as a vacuum film forming method, a printing method, or a metal plating method. In particular, in view of the convenience of fabrication, the conductive member 3 is preferably formed using the same material as that of the wiring 13 provided on the first substrate 1, in the same step as the step of forming the wiring 13.
In the embodiment of the present invention, the conductive member 3 is a loop-shaped member provided so as to surround the anode terminal 4. Therefore, the inner edge of the conductive member 3 can be specified. That is, the inner edge is the edge (contour) of the conductive member 3 facing the anode terminal 4 side. An ideal shape of the inner edge is geometrically described as a closed curve (loop). A closed curve includes, for example, a circle, an ellipse, and a polygon. Practically, the shape of the inner edge (rim) is preferably “circle”. In the embodiment of the present invention, a “circle” is defined as a shape in which the ratio between the minimum and the maximum of a distance from the geometrical center of gravity to the inner edge is 0.92 or greater. When the inner edge has a portion that is sharply pointed toward the anode terminal 4 side, an electric field tends to be concentrated in that portion. Therefore, the inner edge is preferably smooth and even.
In
Since the end of each of the lead-out portions 5 is connected to the prescribed-potential setting unit 21 in the outer space, the conductive member 3 is set to a prescribed potential Vr. The prescribed potential Vr is lower than the anode potential Va. The prescribed potential Vr is preferably closer to the ground potential than to a potential applied to the electron-emitting device 11. The prescribed potential Vr is preferably the ground potential. Current flowing through the conductive member 3 flows into the prescribed-potential setting unit 21 via the lead-out portions 5, which will be described in detail later.
Although not illustrated in the drawings, apart from the lead-out portion 5, a protruding portion (protrusion) that extends toward the edge of the first substrate may be provided as part of the outer edge of the conductive member 3. Different from the lead-out portion 5, the protrusion is a portion that is not directly connected to a unit that defines the potential of the conductive member 3 (e.g., the prescribed-potential setting unit 21). The protrusion is indirectly connected to the prescribed-potential setting unit 21 via the lead-out portion 5. Current does not flow through such a protrusion as current flows through the lead-out portion 5. The protrusion simply has a function of defining a potential nearby to the prescribed potential Vr. For example, in
As described above, the anode terminal 4 is set to the anode potential Va, and the conductive member 3 is set to the potential Vr lower than the anode potential Va. Therefore, the conductive member 3 has a function that intercepts an electric field generated by the anode terminal 4 and reduces the effects of the electric field on members such as the electron-emitting device 11 and the wiring 13.
At the same time, an electric field in accordance with the potential difference between the anode potential Va and the prescribed potential Vr and in accordance with the spatial distance between the anode terminal 4 and the conductive member 3 is generated near the conductive member 3. More specifically, members other than the anode terminal 4, such as the connection electrode 7, the anode 8, and the wiring 13, affect the electric field near the conductive member 3; however, the effect of the anode terminal 4 is dominant.
When a strong electric field is generated near the conductive member 3, electrons may be emitted from the conductive member 3 as a result of the electric field. This may lead to discharge between the conductive member 3 and a member (the anode terminal 4, the connection electrode 7, or the anode 8) set to a potential (anode potential Va) higher than the prescribed potential. In particular, creeping discharge occurs easily between the conductive member 3 and the anode terminal 4.
As a result of the discharge, the conductive member 3 may be damaged. When the conductive member 3 is damaged, the interception effect may become weaker. As a result of the discharge, the wiring 13 may be damaged. When the wiring 13 is damaged, this may affect the driving of the electron-emitting device 11.
For example, discharge in the inner space 300 causes residual gas in the inner space 300 and gas discharged from the rear plate 100, the face plate 200, and the like to become plasma. When this plasma contacts the wiring 13, discharging current may flow into the wiring 13. When discharging current flows into the conductive member 3, induced current may flow into the wiring 13.
In general, when the electron-emitting device 11 is to be normally driven, that is, when electrons are to be emitted, current flowing through the wiring 13 or the electron-emitting device 11 and the drive circuit is expected to range from a few μA to a few mA. In contrast, current generated as a result of discharge may become a large current ranging from a few 100 mA to a few A. When current flows through the electron-emitting device 11 and the drive circuit due to the flow of current through the wiring 13 as a result of discharge, the electron-emitting device 11 and the drive circuit may be damaged depending on the magnitude of the current. Therefore, the flow of current through the wiring 13 as a result of discharge is not favorable. According to the embodiment of the present invention, effects of discharge on the wiring 13, the electron-emitting device 11, and the drive circuit can be reduced.
Features of the embodiment of the present invention will now be described using
In the present invention, the inner edge of the conductive member 3 is represented as a set of multiple (countless) points. The conductive member 3 of the embodiment of the present invention includes, at the inner edge thereof, multiple portions whose distances from the anode terminal 4 are different. In other words, each of the multiple portions is a portion including only one of the multiple points or a portion including a set of consecutive points that are equidistant from the anode terminal 4.
The “distance” used here includes “a spatial distance and a creeping distance”. That is, the multiple portions have different “linear distances” from the anode terminal 4, and different “creeping distances” from the anode terminal 4. A “spatial distance” is the minimum linear distance from any portion of the inner edge of the conductive member 3 to the anode terminal 4. A “creeping distance” is the minimum distance from any portion of the inner edge at the interface between the conductive member 3 and the first substrate 1 to the edge of the interface between the anode terminal 4 and an insulating member (the edge facing toward the conductive member 3), along the surface of the insulating member. The insulating member used here is typically the first substrate 1. When the sealing member 10b or the auxiliary member has an insulating property, or when an insulating depressed-protruding structure is provided on the surface of the first substrate 1, as described later, the insulating member is a path along the surface of these members.
In the embodiment of the present invention, “close to”, “far from”, and “at a distance” refer to positional relationships in relation to the spatial distance. In the configurations illustrated in
In
Also in
Points A and B illustrated in
The portion A indicates, among the multiple portions, a portion closest to the first line 133. The distance between the first line 133 and the portion A is T. T is the minimum value of the spatial distance between the inner edge of the conductive member 3 and the first line 133. In
Therefore, among the multiple portions, portions other than the portion (portion A) closest to the first line 133 each have a distance from the anode terminal 4 that is shorter than RA. Thus, among the multiple portions, discharge occurs more easily in portions (e.g., the portion B) other than the portion A, compared with the portion A. In contrast, discharge occurs less easily in the portion A, compared with the other portions. Since the portion A is the closest portion to the first line 133, effects of discharge on the first line 133 and the electron-emitting device 11 can be reduced by suppressing discharge in the portion A.
The portion B indicates a portion where, among the multiple portions, the distance from the anode terminal 4 is the shortest. The spatial distance between the portion B and the anode terminal 4 is Rmin. That is, Rmin is the minimum value of the spatial distance between the inner edge of the conductive member 3 and the anode terminal 4.
As is clear from
In particular, the portion B is preferably positioned outside the intermediate region. That is, preferably the portion B is positioned in the non-intermediate region and belongs to the inner edge of the non-intermediate part 32. If the portion B is positioned in the intermediate region, current that has occurred as a result of discharge flows via the intermediate part 31. In contrast, when the portion B is positioned in the non-intermediate region, the probability of current that has occurred as a result of discharge flowing via the intermediate part 31, or the proportion of current flowing via the intermediate part 31 out of current that has occurred as a result of discharge, can be reduced.
In
Also in
Here, the spatial distance between the anode terminal 4 and the column wiring 131 is S1. In
Points A1, A2, and B illustrated in
Among the multiple portions, the portions A1 and A2 are portions that are closest to the wiring 13. More specifically, the portion A1 is a portion that is closest to the column wiring 131, and the portion A2 is a portion that is closest to the row wiring 132. The distance between the column wiring 131 and the portion A1 is T1. T1 is the minimum value of the spatial distance between the inner edge of the conductive member 3 and the column wiring 131. In
The portion B is, among the multiple portions, a portion whose distance from the anode terminal 4 is the shortest, as in the portion B described in the configuration illustrated in
Among the multiple portions, portions (e.g., the portion A2 and the portion B) other than the portion A1 have shorter distances from the anode terminal 4, compared with the portion A1. Thus, discharge occurs more easily in these portions than in the portion A1. In contrast, discharge occurs less easily in the portion A1 than in the other portions. Since the portion A1 is a portion that is closest to the column wiring 131, effects of discharge on the column wiring 131 and the electron-emitting device 11 can be reduced by suppressing discharge in the portion A1.
The column wiring 131 that is most adjacent to the portion A1 is thinner than the row wiring 132, and the column wiring 131 breaks easily. Since the spatial distance (T1) between the portion A1 and the column wiring 131 is shorter than the spatial distance (T2) between the portion A2 and the row wiring 132, it is more likely that discharge affects the column wiring 131. As in this configuration, when RA1 is longer than RA2, effects of discharge on the column wiring 131 can be reduced more preferentially to effects of discharge on the row wiring 132.
The spatial distance between the anode terminal 4 and the column wiring 131 is S1. In
A part 33 indicated by pale hatching and a part 34 indicated by dark hatching in
More specifically, the intermediate region includes, as in the configuration illustrated in
Points A1, A2, and B illustrated in
The intermediate region can be divided into a first intermediate region and a second intermediate region. A part of the conductive member 3 that is positioned in the first intermediate region is the first intermediate part 33 indicated by dark hatching in
The first intermediate region is a region in which the spatial distance from the row wiring 132 is less than or equal to the spatial distance between the portion A1 and the row wiring 132, and the spatial distance from the column wiring 131 is less than or equal to the spatial distance between the portion A2 and the column wiring 131. In
Therefore, the inner edge of the first intermediate part 33 includes, of two paths connecting the portions A1 and A2 along the inner edge, one path that is closer to the column wiring 131 or the row wiring 132. Geometrically describing using
Among the multiple portions, a portion that belongs to the second intermediate part 34 and a portion (e.g., the portion B) that belongs to the non-intermediate part 32 each have a shorter distance from the anode terminal 4, compared with the portions A1 and A2. Therefore, discharge occurs less easily in the portions A1 and A2 than in the portion B. Therefore, effects of discharge on both the column wiring 131 and the row wiring 132 can be reduced. Thus, effects on the electron-emitting device 11 can be further reduced.
In this configuration, the portion B is preferably positioned on, of two paths connecting the portions A1 and A2 along the inner edge, one path that is farther from the column wiring 131 or the row wiring 132. That is, the portion B is preferably provided in the second intermediate part 34 or the non-intermediate part 32. When the portion B belongs to the second intermediate part 34 that is a part positioned in a region outside the first intermediate region or the non-intermediate part 32, the probability of current that has occurred in the portion B flowing via the portion A1 or A2 can be reduced. In contrast, when the portion B is provided in the first intermediate part 33, current that has occurred as a result of discharge flows via at least one of the portions A1 and A2. Therefore, the portion B is preferably positioned in a region outside the intermediate region (the first intermediate region and the second intermediate region), that is, more preferably, the portion B belongs to the non-intermediate part 32.
A point C illustrated in
In this configuration, the distance from the anode terminal 4 becomes longer as a portion approaches from the portion A1 or A2 to the portion C. In this manner, a portion that is positioned closer to the row wiring 132 than the portion A1 is and that is positioned closer to the column wiring 131 than the portion A2 is preferably has a longer distance from the anode terminal 4 than the portions A1 and A2. That is, a portion whose distance from the anode terminal 4 is shorter than the portions A1 and A2 is not preferably provided in the first intermediate part 33. A portion (portion C) whose distance from the anode terminal 4 is the longest is preferably provided in the first intermediate region. Accordingly, the probability of current that has occurred as a result of discharge flowing via the portion A1 and/or A2 can be reduced.
In the configurations described so far, practically the spatial distance Rmin between the anode terminal 4 and the portion B is preferably 500 μm or greater. Also, the spatial distance between the anode terminal 4 and the portion A (A1 or A2) is preferably 1.2 times as great as Rmin or greater, and more preferably 1.5 times as great as Rmin or greater.
The length of the inner edge of the first intermediate part 33 is preferably as short as possible, and the length of the inner edge of the first intermediate part 33 is preferably shorter than ¼ of the entire length (perimeter) of the inner edge. The length of the inner edge of the first intermediate part 33 is the length of, of two paths connecting the points A1 and A2 along the inner edge, one path that is closer to the wiring 13 (the column wiring 131 and the row wiring 132). If discharge occurs in the first intermediate part 33, current that is generated as a result of the discharge flows through the point A and/or the point B. The possibility of the occurrence of discharge in the first intermediate part 33 can be further reduced by reducing the length of the inner edge of the first intermediate part 33. When the inner edge of the conductive member 3 is circular, the length of the inner edge of the first intermediate part 33 can be made shorter than ¼ of the entire length of the inner edge by increasing the angle θ formed by the column wiring 131 and the row wiring 132 to be greater than 90°. The length of the inner edge of the first intermediate part 33 can be made shorter by appropriately designing the shape of the wiring 13 and/or the shape of the conductive member 3. The foregoing angle θ is the smaller one of two angles (θ and 360°−θ) formed by column wiring 13 that faces the conductive member 3 and that is closest to the conductive member 3 and row wiring 132 that faces the conductive member 3 and that is closest to the conductive member 3, and the foregoing angle θ does not exceed 180°. In
According to the configurations described above, occurrence of discharge in the portions of the conductive member 3 closer to the wiring 13 can be suppressed, and effects on the wiring 13 and the electron-emitting device 11 can be reduced. Specifically, occurrence of discharge the immediate part 31 can be suppressed. The conductive member 3 including a portion (e.g., the portion B) whose distance from the anode terminal 4 is shorter than portions (portions A, A1, and A2) closest to the wiring 13 can effectively control occurrence of discharge.
Next, exemplary preferred configurations of the position of the lead-out portion 5 will be described using
The lead-out portion 5 preferably extends at a greater distance from the wiring 13 than the portions (portions A, A1, and A2) that are closest to the wiring 13 are. That is, as shown in
In contrast, in the configuration illustrated in
The embodiments in which the inner edge of the conductive member 3 has multiple portions whose distances from the anode terminal 4 are different have been described so far. However, the phenomenon in which current that is induced by current flowing through the lead-out portion 5 flows through the wiring 13 occurs, regardless of the positional relationship between the conductive member 3 and the anode terminal 4. For example, this phenomenon occurs when the distances (RA) between portions (portions A, A1, and A2), among the multiple portions, that are closest to the wiring 13 and the anode terminal 4 are the shortest (RA, RA1, and/or RA2=Rmin). Alternatively, this phenomenon occurs when the distance between the inner edge of the conductive member 3 and the anode terminal 4 is constant, that is, when all of the multiple (countless) points of the conductive member 3 are equidistant from the anode terminal 4, as shown in
The induced current can be further reduced as the current path becomes more distant from the wiring 13 (the column wiring 131 and the row wiring 132). Therefore, by providing the lead-out portion 5 (51 and 52) at a greater distance from the wiring 13 (the column wiring 131 and the row wiring 132) than the point (or portion) A (A1 and A2) is, effects of current flowing through the lead-out portion 5 (51 and 52) on the wiring 13 can be reduced.
Also, the induced current can be further reduced when the angle formed by the lead-out portion 5 and the wiring 13 (the column wiring 131 and the row wiring 132) is not in parallel, as illustrated in
The lead-out portion 5 extends from a point D (portion D) on the inner edge. The point D is a point that belongs to the inner edge of a part different from the first intermediate part 33. In
It is preferable to provide a point on the inner edge side of the lead-out portion 5 (e.g. point D) at a position with a greater distance from the wiring 13 than a point which is closest to the wiring 13 among multiple points of the inner edge at which tangents relative to the inner edge define 45° to the wirings 13. The multiple points whose angle of tangent is defined 45° is defined to the column wiring 131, the row wiring 132, the first line 133 respectively. As in
As described so far, the induced current can be suppressed by appropriately setting the angle formed by the lead-out portion 5 and the wiring 13 or the angle formed by the tangent at the point on the inner edge side of the lead-out portion 5 and the wiring 13. This is because the magnitude of a vector component in a direction in which, of a magnetic field generated by discharge current flowing through each point of the conductive member 3, an induced electromotive force is generated in the wiring 13 is proportional to the cosine function of the foregoing angle. That is, when the foregoing angle becomes 90°, the magnitude of a vector component in a direction in which an induced electromotive force is generated in the wiring 13 becomes minimum since) cos(90°)=0. When the foregoing angle becomes 0°, the magnitude of the same vector becomes maximum since) cos(0°)=1. When the foregoing angle is greater than 45° and less than or equal to 90°, the extent of a change (represented by the sine function, which is the derivative of the cosine function) in the magnitude of a vector component in a direction in which an induced electromotive force is generated in the wiring 13 becomes significantly small, compared with the case where the foregoing angle is greater than or equal to 0° and less than or equal to 45°.
As illustrated in
In the configuration illustrated in
In the configuration illustrated in
As described above, the portion B is a portion where discharge occurs most easily among the multiple portions of the inner edge. Current generated as a result of discharge flows from the portion B through a clockwise path or a counterclockwise path in the figure, or flows through both these paths. Therefore, when there is only one lead-out portion, current may flow via a portion closest to the wiring 13. For example, when there is only the lead-out portion 51 in
In contrast, when the lead-out portions 51 and 52 extend from the portions D1 and D2, respectively, it is highly likely that current generated in the portion B flows through the lead-out portion 51 and/or the lead-out portion 52, and does not flow via the portion A (the portion A1 and the portion A2). The path of current in the case where discharge occurs in the portion B as a result of the foregoing is indicated by solid arrows in
In the configuration illustrated in
Therefore, when the portion B is provided in the non-intermediate part 32, as illustrated in
As in the foregoing embodiments, the ratio of the distance of a path along the inner edge from a portion where discharge occurs (typically the portion B) to the portion D1 and the distance of a path along the inner edge from a portion where discharge occurs to the portion D2 serves as a key factor in the ratio of the magnitude of current in a clockwise path and the magnitude of current in a counterclockwise path from a portion where discharge occurs.
The configurations have been described so far in which the inner edge (rim) of the conductive member 3 is circular, the outer edge (surface) of the anode terminal 4 is circular, and the center of the outer edge of the anode terminal 4 is shifted from the center of the inner edge of the conductive member 3 in a direction deviating from the wiring 13. In this case, as described above, the multiple portions are typically numerous points.
In a configuration illustrated in
In a configuration illustrated in
In the configurations illustrated in
As illustrated in
In an embodiment of the present invention, a pressure-tight structure for suppressing discharge is preferably provided in the vicinity of the anode terminal 4. As an example of the pressure-tight structure, configurations described in Japanese Patent Laid-Open Nos. 2007-109603 and 2006-222093 may be used.
The inner edge of the conductive member 3 is preferably covered with an insulating film. Accordingly, emission of electrons from the conductive member 3 is suppressed, and occurrence of discharge is suppressed. As a material of the insulating film, a material whose volume resistivity is 106 Ωm or greater is preferably used, and a material whose relative dielectric constant ranges from 3 to 10 is preferably used.
Also, an antistatic film is preferably provided on the first substrate 1 between the conductive member 3 and the anode terminal 4. Accordingly, electrification of the surface of the first substrate 1 can be suppressed, and discharge can be suppressed. The sheet resistance of the antistatic film is preferably 107 Ω/□ or greater and 1014 Ω/□ or less. A material made of a metal nitride, oxide, or carbide may be used.
Also, at least one of an insulating depressed structure and an insulating protruding structure (hereinafter referred to as a “depressed-protruding structure”) is preferably provided on the first substrate 1 between the conductive member 3 and the anode terminal 4. Accordingly, the creeping distance can be increased, and discharge can be suppressed. The depressed-protruding structure may be a periodical structure or a random structure. A depressed structure may be formed by providing a recess. A protruding structure may be formed by providing an insulating member with 106 Ωm or greater on the surface 101 of the first substrate 1. With a protruding structure, not only the creeping distance is increased, but also the protruding structure may function as a barrier against emitted electrons.
In
The display panel 1000 will be further described. The pressure in the inner space 300 of the display panel 100 is preferably 1×10−5 Pa or less. Also, a spacer (not illustrated) for defining the interval between the rear plate 100 and the face plate 200 may be provided.
Spint type, surface-conduction type, MIM type, or MIS type electron-emitting devices may be used as the electron-emitting devices 11, and the type is not particularly limited.
In the matrix wiring described so far, for illustrative purposes, it has been described that the column wiring 131 is connected to the gate of the electron-emitting device 11, and the row wiring 132 is connected to the cathode of the electron-emitting device 11. Also, it has been described that the column wiring 131 is below the row wiring 132. However, the column wiring 131 may be connected to the cathode of the electron-emitting device 11, and the row wiring 132 may be connected to the gate of the electron-emitting device 11. Also, the row wiring 132 may be below the column wiring 131. Also, the configurations in which the width of the column wiring 131 is less than the width of the row wiring 132 have been illustrated. However, the width of the column wiring 131 may be greater than the width of the row wiring 132, or the column wiring 131 and the row wiring 132 may have the same width.
When ladder-type wiring is used, a grid electrode for selecting at least one of multiple electron-emitting devices 11 connected to the first line 133 and the second line 134 may be provided between the electron-emitting devices 11 and the anode 8.
The guard electrode 6 is provided on the surface 201 of the second substrate 2, at a distance from the connection electrode 7 and the anode 8, so as to surround the outer edge of the anode 8. The guard electrode 6 is preferably set to the ground potential. The guard electrode 6 is provided to set the potential in the vicinity of the anode 8.
In the display panel 1000, one pixel or sub-pixel may include a corresponding one of the electron-emitting devices 11 and the light-emitting members 12 disposed so as to face the electron-emitting device 11. Full-color display can be performed by constructing one pixel by arranging sub-pixels having light-emitting members 12 that exhibit red, green, and blue luminescent colors. A black matrix that defines sub-pixels and pixels may be provided on the surface 201 of the second substrate 2. Also, color filters may be provided between the light-emitting members 12 and the second substrate 2.
Next, the display apparatus will be described in detail. As described above, the display apparatus at least includes the display panel 1000, the anode-potential setting unit 20, the prescribed-potential setting unit 21, and the drive circuit for driving the electron-emitting devices 11.
As illustrated in
As illustrated in
The display panel 1000 of the embodiment of the present invention may be used in an image display apparatus that is a display apparatus for displaying an image or a television apparatus.
A drive circuit 2000 including a scanning circuit and a modulation circuit may be used as a drive circuit used in the image display apparatus 4000. The image display apparatus 4000 can select and drive any electron-emitting device from among the electron-emitting devices 11, and cause the light-emitting members 12 to emit light at a desired gradation level. For example, the scanning circuit may be configured to include the cathode-potential setting unit 22, and the modulation circuit may be configured to include the gate-potential setting unit 23. Typically, the modulation circuit is connected to the column wirings 131, and the scanning circuit is connected to the row wirings 132. The scanning circuit outputs a scanning signal as the cathode potential Vg. The modulation circuit outputs a modulation signal as the gate potential Vg. The modulation signal is modulated in accordance with a display gradation level by using pulse-width modulation (PWM), pulse-amplitude modulation (PAM), or a modulation method combining PWM and PAM. The drive circuit 2000 performs line sequential scanning of the display panel 1000 in increments of row wiring 131. Typical line sequential scanning methods include a progressive method and an interlaced method. Since the frequency of a modulation signal is generally higher than the frequency of a scanning signal, noise on the modulation signal has a great effect on a display image. Therefore, preferably, the effect of discharge near the anode terminal 4 on wiring (e.g., column wiring 131) to which the modulation circuit is connected and a modulation signal is input is made preferentially smaller than the same effect on wiring (e.g., row wiring 132) to which the scanning circuit is connected and a scanning signal is input. The image display apparatus may include a control circuit 3000. The control circuit 3000 applies correction processing, suited for the display panel 1000, on an input image signal, and outputs the corrected image signal and various control signals to the drive circuit 2000. Correction processing includes, for example, inverse gamma correction. Based on the corrected image signal, the drive circuit 2000 outputs the scanning signal and the modulation signal as a drive signal to the display panel 1000.
The display panel 1000 of the embodiment of the present invention may be used in a television apparatus.
The television apparatus includes a receiving circuit 6000, an interface (I/F) unit 5000, and the image display apparatus 4000.
The receiving circuit 6000 receives a television signal including image information. A television signal can be received from broadcasting such as satellite broadcasting, terrestrial broadcasting, or cable-television, from communication such as the Internet or a video conference system, from an image input apparatus such as a camera or a scanner, or from an image storage apparatus such as a video recorder that stores image information. The receiving circuit 6000 may include a tuner and/or a decoder as needed. The receiving circuit 6000 outputs an image signal obtained by decoding the television signal to the I/F unit 5000.
The I/F unit 5000 converts the image signal into a display format of the image display apparatus 4000, and outputs the image signal to the image display apparatus 4000. Accordingly, an image in accordance with the television signal is displayed on the display panel 1000 of the image display apparatus 4000. According to the embodiment of the present invention, effects of discharge within the display panel 1000 are reduced. Therefore, a highly reliable television apparatus can be obtained.
In this Example, a display panel illustrated in
First, a glass substrate was prepared as the first substrate 1. The through hole 10a with a diameter of 2 mm was formed near the corner of the glass substrate 1. Multiple surface-conduction electron-emitting devices 11 were formed on the glass substrate 1 by using a known method.
The matrix wiring 13 (column wirings 131, inter-layer insulating layer (not illustrated), and row wirings 132) was formed on the glass substrate 1 by using a screen printing method that employs a Ag paste and a screen printing method that employs an insulating paste.
The circular conductive member 3 with an inside diameter of 10 mm, a width of 1 mm, an outside diameter of 12 mm, and a thickness of 10 μm was formed so as to surround the through hole 10a by using a screen printing method that employs a Ag paste. The conductive member 3 was formed so that the center of the inner periphery of the conductive member 3 was shifted by 0.5 mm from the center of the through hole 10a, in a direction of 45° (+X direction serves as 0°, and +Y direction serves as)90°. As illustrated in
In this manner, the rear plate 100 including the surface-conduction electron-emitting devices 11 and the matrix wiring 13 on the glass substrate 1 was fabricated.
Thereafter, the anode terminal 4 with a diameter of 1 mm was inserted into the through hole 10a. Since a material of the anode terminal 4 is preferably a material whose expansion coefficient is similar to that of the substrate (glass) in view of the mechanical strength, a 426 alloy was used. The anode terminal 4 was fixed to the side of the glass substrate 1, on which the matrix wiring 13 was provided, using the conductive sealant 10b. The through hole 10a was filled up using the sealant 10b. The sealant 10b was provided, around the through hole 10a, so as to have an outside diameter of 5 mm and to be concentric with the center of the through hole 10a. The minimum spatial distance (Rmin) between the conductive sealant 10b and the conductive member 3 was 2 mm, and the maximum spatial distance (Rmax) between the conductive sealant 10b and the conductive member 3 was 3 mm. Also, the spatial distances (RA1 and RA2) between the conductive sealant 10b and the portions closest to the wiring 13 were approximately 2.7 mm.
A transparent glass substrate was prepared as the second substrate 2. A conductive black member (black matrix) with an opening where the light-emitting members 12 are to be disposed was formed on the second substrate 2. Photosensitive carbon black was used as a material of the conductive black member, and the conductive black member had a thickness of 10 μm. The photosensitive carbon black was exposed to light and patterned so as to have an opening, and this opening of the conductive black member was filled with R, G, and B phosphors serving as the light-emitting members 12. By using a screen printing method, the phosphors of the three colors including R, G, and B were formed with a thickness of 10 μm in the opening of the conductive black member. As the anode 8, an aluminum film was deposited at a thickness of 100 nm on the entire surface of the conductive black member and the phosphors by using an evaporation method.
As above, the face plate 200 including the anode 8 and the light-emitting members 12 was fabricated on the glass substrate 2.
Next, a plate-shaped spacer that defines the interval between the rear plate 100 and the face plate 200 was prepared. With the spacer, the rear plate 100 and the face plate 200 were disposed facing each other, and the interval therebetween was defined to 1.6 mm. The rear plate 100 and the face plate 200 were joined using the frame member 9 being provided therebetween. Joining portions were hermetically sealed using low melting point metal.
From the interior of the hermetically-sealed container fabricated as above, air was pumped out through an exhaust hole provided in the hermetically-sealed container. Thereafter, the exhaust hole was sealed, so that the inner space 300 was maintained as a vacuum. Accordingly, the display panel 1000 was obtained. A power supply that can generate a voltage at 10 kV or greater was connected to the anode terminal 4 of the display panel 1000.
The wiring 13 and the lead-out portions 51 and 52 were grounded, and a potential of +30 kV was applied to the anode terminal 4. As a result, discharge occurred during a boosting operation. After a certain time had elapsed, the boosting operation was repeated. It was observed that, when discharge was caused to occur 10 times, the discharge occurred at all times near the corner of the display panel 1000, rather than near the anode terminal 4. It was also observed that, when discharge was caused to occur a certain number of times, potential generated as a result of the discharge was increased. From this point, it can be regarded that a conditioning effect was achieved as a result of discharge.
It was also observed that, when discharge occurred a certain number of times, current always flowed through the lead-out portions 51 and 52. However, current flowing through the column wiring 131 or the row wiring 132 was hardly observed.
Thereafter, +12 kV was applied to the anode terminal 4, and the electron-emitting devices 11 were driven to cause the phosphors to emit light. No discharge was observed within one hour or more, and favorable display was achieved. Further, +16 kV was applied to the anode terminal 4 to cause the phosphors to emit light. Discharge occurred during display, but effects on the display quality were hardly observed.
As a comparative example, the conductive member 3 was formed concentrically with the through hole 10a, and the display apparatus was fabricated. Since only the positional relationship among the conductive member 3, the matrix wiring 13, and the anode terminal 4 is different from that in the Example, and the positional relationship between the anode terminal 4 and the matrix wiring 13 and the other manufacturing methods are the same as those in the Example, repeated descriptions are omitted.
The circular conductive member 3 with an inside diameter of 10 mm, a width of 1 mm, an outside diameter of 12 mm, and a thickness of 10 μm was formed so as to surround the through hole 10a by using a screen printing method that employs a Ag paste. The conductive member 3 was formed so that the center of the inner periphery of the conductive member 3 becomes concentric with the center of the outer periphery of the through hole 10a.
The lead-out portion 51 was formed in parallel with the column wiring 131 so as to have a width of 1 mm from the position at a further distance of 0.5 mm from the column wiring 131, compared with the portion (A1) of the inner edge of the conductive member 3 that is closest to the column wiring 131. The lead-out portion 52 was formed in parallel with the row wiring 132 so as to have a width of 1 mm from the position at a further distance of 0.5 mm from the row wiring 132, compared with the portion (A2) of the inner edge of the conductive member 3 that is closest to the row wiring 132.
The sealant 10b was provided, around the through hole 10a, so as to have an outside diameter of 5 mm and to be concentric with the center of the through hole 10a. The distance between the conductive sealant 10b and the conductive member 3 was 2.5 mm in all directions.
As in the Example, when discharge was caused to occur 10 times, discharge occurred at a position at a greater distance from the matrix wiring 13 than the anode terminal 4 is, and discharge also occurred at a position closer to the matrix wiring 13 than the anode terminal 4 is. That is, discharge occurred at different positions. Compared with the Example, the conditioning effect was small.
It was also observed that, when discharge occurred a certain number of times, current always flowed through the lead-out portions 51 and 52. Also, large current sometimes flowed through the column wiring 131 and the row wiring 132.
Thereafter, +12 kV was applied to the anode terminal 4, and the electron-emitting devices 11 were driven to cause the phosphors to emit light. Although no discharge was observed within one hour or more, the luminance levels of some pixels corresponding to the column wiring 131 near the anode terminal 4 were lower than those of pixels of columns corresponding to the other column wirings 131. This resulted in a streaky dark line. Further, +16 kV was applied to the anode terminal 4 to cause the phosphors to emit light. Discharge occurred during display, and, as a result of the discharge, effects on a display image were observed.
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 such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Applications No. 2009-149798, filed Jun. 24, 2009, and No. 2010-125990, filed Jun. 1, 2010, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-149798 | Jun 2009 | JP | national |
| 2010-125990 | Jun 2010 | JP | national |
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