Patent Grant
6963159
1. Field of the Invention
The present invention relates to an electron beam apparatus having an electron source for emitting electrons, and used as an image-forming apparatus, and a spacer for internally supporting an enclosure device arranged in the electron beam apparatus, and more particularly to an electron beam apparatus having a surface-conduction electron emitter device working as an electron source, and a spacer.
2. Description of the Related Art
Two types of electrode emitters, a hot-cathode type electron source and cold-cathode type electron source, are known. The cold-cathode type electron sources include a field emission (FE) device, metal/insulator/metal (MIM) device, surface-conduction electron emitter (SCE) device, etc.
The surface-conduction electron emitter device uses the phenomenon that electrons are emitted if a current flows through the surface of a small-sized, thin film formed on a substrate in a direction parallel with the surface of the thin film. Among such surface-conduction electron emitter devices, there is one device proposed by Elinson employing an SnO2 film, and another device proposed by employing an Au thin film, an In2O3/SnO2 thin film, or a carbon thin film.
Since the surface-conduction electron emitter device from among the cold-cathode devices is simple in construction and easy to manufacture, a number of devices can be formed over a wide surface area. The application of the surface-conduction electron emitter device as an image-forming apparatus such as an image display device, or an image recording device, or a charged beam source has been extensively studied.
One application example of the image display apparatus includes a spacer substrate, a faceplate as a second member having a fluorescent material, and a rear plate as a first member having an electron source. The space between the faceplate and the rear plate is maintained in a vacuum.
There is a potential difference between the faceplate and the rear plate with the faceplate set at a potential higher than that of the rear plate. Arranged on the rear plate are an electron emitter that emits electrons, a driving circuit that drives the electron emitter, and wiring electrodes that connect the electron emitter to the driving circuit. When the electron emitter is driven by the wiring electrodes, electrons are emitted from the electron emitter toward the faceplate, and the fluorescent material on the faceplate forms a desired image.
The spacer substrate interposed between the faceplate and the rear plate maintains the gap between the faceplate and the rear plate against the atmospheric pressure. The spacer substrate must have a sufficient mechanical strength to withstand the atmospheric pressure. It is also important to make sure that the spacer substrate does not affect the trajectory of electrons traveling between the rear plate and the faceplate.
The charge accumulated in the spacer substrate greatly affects the trajectory of electrons traveling between the rear plate and the faceplate. Some of the electrons emitted from the electron emitter or electrons reflected off the faceplate enter the spacer substrate, causing secondary electrons to be emitted from the spacer substrate. Also, ions caused as a result of the collision of electrons sticks to the surface of the spacer substrate. As a result, the spacer substrate is charged.
If the spacer substrate is positively charged, electrons flying within a close range therefrom are attracted by the spacer substrate. These electrons are deflected from a trajectory thereof to form a desired image. The resulting image on the faceplate is thus subject to distortion. The attractive force acting on the electrons becomes large as the electrons fly near the spacer substrate. The nearer the electrons are to the spacer substrate, the larger the distortion of the image on the faceplate. In such an image display apparatus, the electron trajectory is deviated more when the electrons reach the faceplate as the spacing between the rear plate and the faceplate is increased. The distortion in the image becomes pronounced.
To control the distortion of the image, an electrode for correcting the electron trajectory is conventionally formed in the spacer substrate, or the spacer substrate is conventionally coated with a resistive film having a high resistance for conduction, thereby allowing a slight current to flow and thereby to remove a charge therefrom.
In another method, spacer electrodes are arranged on the spacer substrate at the contact points thereof with each of the faceplate and the rear plate to apply a uniform electric field to a coating material of the spacer substrate. This arrangement prevents the spacer substrate from being damaged by poor contacts or concentration of current.
As disclosed in Japanese Laid-Open Patent Application No. 2000-311632, the surface of the spacer substrate is ruggedized, and is then coated with a high-resistance material to control the amount of charge in the spacer substrate.
Using the above-mentioned techniques, the conventional electron apparatus controls the electrons traveling close to the spacer from being attracted by the spacer, and corrects the distortion in the image.
A high definition requirement on the image display apparatus is currently mounting, and there is a need for an electron beam apparatus that controls the electron beam with a high accuracy.
It is an object of the present invention to provide an electron beam apparatus and a spacer for controlling an electron beam with a higher accuracy.
An image-forming apparatus in a first aspect of the present invention includes a first substrate, a second substrate, and a spacer that defines the spacing between the first substrate and the second substrate, wherein the spacer includes a portion ruggedized with grooves on the surface thereof exposed in the space between the first substrate and the second substrate. The grooves extend in a striped fashion in substantial parallel with the first substrate and the second substrate. The ruggedized portion includes a plurality of regions which are different from each other in the ruggedized configuration.
Preferably, the surface is divided into a plurality of regions which are different in at least one of the average pitch of the grooves and the average depth of the grooves.
In the image-forming apparatus of the present invention, the spacer includes the ruggedized portion having the grooves extending in substantial parallel with the first substrate and the second substrate. The ruggedized portion includes a plurality of regions different in the ruggedized configuration. In this way, the charged state on the surface of the spacer becomes different from region to region. The trajectory of the electron beam is controlled as desired and is thus free from disturbance.
Generally, a ruggedized substrate coated with a resistive film has a larger resistance than a flat substrate (a substrate having a flat surface) coated with the same resistive film. This is because the ruggedized substrate has a longer length of the resistive film per unit length. The inventors of this invention have found that a combination of a particular material for the resistive film and a manufacturing method of the spacer increases a change in resistance on the ruggedized substrate.
The material is a nitrogen compound of tungsten (W) and germanium (Ge).
By appropriately changing the depth of the grooves or the pitch of the grooves from surface region to surface region, a spacer having a desired resistance distribution is formed in a direction in a spacing between a second substrate (a faceplate) and a first substrate (a rear plate). The trajectory of the electron beam is corrected to a desired location by adjusting the resistance distribution on the surface of the space.
A desired potential distribution is formed by using a region having no ruggedness. The region having no ruggedness is thus free from the pitch, depth, and number of the grooves. The purpose of the present invention is achieved by incorporating a combination of ruggedized portions. The potential distribution depends on the spacer, the construction of panels, driving conditions, etc., and is not determined by any single factor. The inventors of this invention have found that the electrons are repelled from the spacer or attracted to the spacer by charge under the following conditions.
(1) The average pitch of the grooves formed on the spacer from a half-way point up to the faceplate is smaller than the average pitch of the grooves formed on the spacer from the half-way point down to the rear plate.
(2) The average depth of the grooves formed on the spacer from the half-way point up to the faceplate is larger than the average depth of the grooves formed on the spacer from the half-way point down to the rear plate.
(3) The number of the grooves formed on the spacer from the half-way point up to the faceplate is greater than the number of the grooves formed on the spacer from the half-way point down to the rear plate.
It is important that the grooves of the spacer on the faceplate side be smaller in pitch, deeper in depth, or larger in number than the grooves of the spacer on the rear plate side. The segmentation position (border) of the regions is not necessarily at the half-way point of the spacer. It suffices to satisfy the above requirement, if compared with respect to the half-way point.
The spacer of the present invention having the ruggedized configuration may be produced using any technique. For example, the spacer may be produced from a material, which is softened with heat, using a molding technique, or may be produced by cutting a material. In particular, glass may be cut or molded into a ruggedized configuration, and extended in the vicinity of or above the softening point thereof. This method is excellent from the standpoint of bulk production. The spacer of the present invention may have no ruggedness on a portion thereof to facilitate bulk production.
In accordance with the present invention, the substantially entire surface of the spacer extending between the faceplate and the rear plate is ruggedized to control charge accumulation. The electrode function of the ruggedized portion allows the electron beam to be easily corrected in trajectory. A quality image is thus presented.
Further objects, features, and advantages of the present invention will be apparent from the following description of the preferred embodiments with reference to the attached drawings.
An electron beam apparatus and a spacer thereof in accordance with one embodiment of the present invention will now be discussed in detail with reference to the drawings. The following discussion focuses on the construction, the operation and the manufacturing method of the image display apparatus, which is one application of the electron beam apparatus of the present invention.
A thin spacer is fixed between the faceplate 402 and the rear plate 403 to maintain the spacing between the faceplate 402 and the rear plate 403 against the force of the atmospheric pressure. A single spacer is shown in
The high-resistance resistive films 404a and 404b are deposited on at least the surface of the dielectric component 401 exposed to the vacuum in the air-tight container, and are electrically connected to the metal back (not shown) formed on the internal surface of the faceplate 402 and a wiring electrode 406 on the surface of the rear plate 403 respectively through the spacer electrodes 405b and 405a. The spacer must have insulation high enough to withstand a high voltage applied between the wiring electrode 406 on the rear plate 403 and the metal back on the faceplate 402 and conductivity enough to prevent static charge accumulation on the surface of the spacer. Such a dielectric component 401 of the spacer may be formed of quartz glass, glass having no or reduced impurity content such as sodium (Na), soda-lime glass, or ceramic such as alumina. The dielectric component 401 has preferably a coefficient of thermal expansion close to that of the air-tight container or the rear plate 403.
A current flows through the high-resistance resistive films 404a and 404b. The current is determined by dividing an acceleration voltage Va applied to the faceplate 402 at a high voltage side by the sum Rs of resistances of the high-resistance resistive films 404a and 404b as an anti-static film. The sum Rs of resistances of the high-resistance resistive films 404a and 404b is determined from the standpoint of preventing static charge accumulation and saving power. From the standpoint of preventing the static charge accumulation, the surface resistance R/square of each of the high-resistance resistive films 404a and 404b is preferably 1014 Ω or less. More preferably, the surface resistance R/square of the high-resistance resistive films 404a and 404b is preferably 1013 Ω or less. The lower limit of the surface resistance R/square of the high-resistance resistive films 404a and 404b is preferably 107 Ω or more, although the lower limit depends on the configuration of the spacer and the voltage applied to the spacer.
The thickness t of the high-resistance (anti-static) films 404a and 404b preferably falls within a range of 10 nm to 50 μm. The thin film is formed in an island if the film is thinned to less than 10 nm, and the resistance thereof becomes unstable and lacks repeatability, although these depend on the surface energy of the film, the bond of the film with the substrate, and the temperature of the substrate. If the thickness of the film is set to be 50 μm or more, the dielectric component 401 is likely to be deformed.
Let ρ represent a specific resistance of the high-resistance resistive films 404a and 404b, and the surface resistance R/square is ρ/t. From the above-mentioned preferable ranges of R/square and t, the specific resistance ρ of the high-resistance resistive films 404a and 404b preferably falls within a range of 104 Ω·cm to 1010 Ω·cm. From the above-mentioned more preferable ranges of R/square and t, the specific resistance ρ of the high-resistance resistive films 404a and 404b more preferably falls within a range of 105 Ω·cm to 109 Ω·cm.
When a current flows through the high-resistance resistive films 404a and 404b, or when the entire image display apparatus generates heat, the spacer rises in temperature. If the temperature coefficient of the high-resistance resistive films 404a and 404b is a large negative value, the resistance thereof drops with a temperature rise, and the current flowing through the films increases. The spacer further rises in temperature. The current then continuously increases to a current runaway in excess of a limit of the power supply. The condition under which the current runaway occurs is generally characterized by TCR (Temperature Coefficient of Resistance) of a resistor expressed by equation (1).
TCR=(ΔR/ΔT)/R×100 [%/° C.] (1)
where ΔT represents an increase in the temperature spacer with respect to room temperature, and ΔR represents an increase in the resistance of the resistor during actual operating conditions.
Experience shows that the condition of TCR under which the current runaway occurs is −1%/° C. or lower. Specifically, the temperature coefficient of the high-resistance resistive films 404a and 404b is preferably set to be greater than −1 [%/° C.].
The high-resistance resistive films 404a and 404b having an anti-static property are preferably fabricated of a metal oxide. Among the metal oxides, the metal oxide of one of chromium (Cr), Nickel (Ni), and copper (Cu) is preferable. This is because a relatively small secondary emission efficiency of these compounds makes it less possible for the spacer to be charged when electrons emitted from the electron emitters 407a, 407b, and 407c collide with the spacer. Besides the metal oxides, carbon is preferred as a material for the high-resistance resistive films 404a and 404b because of the smaller secondary electron emission efficiency thereof. In particular, amorphous carbon has a high resistance. If amorphous carbon is used for the high-resistance resistive films 404a and 404b, the resistance of the spacer is easily controlled to a desired value.
The nitride of aluminum and a transition-metal compound is used for the high-resistance resistive films 404a and 404b having an anti-static property. Since the nitride of aluminum and the transition-metal compound is controlled in a wide resistance range from an electrically conductive state to a dielectric state, the nitride of aluminum and the transition-metal compound is preferable. Furthermore, the nitride of aluminum and the transition-metal compound is stable, and suffers less variations in resistance in a manufacturing process of the display apparatus to be discussed later. The temperature coefficient thereof is higher than −1 [%/° C.], and is easy to use. The transition-metal element may be titanium (Ti), chromium (Cr), tantalum (Ta), etc.
A nitride film is deposited on the dielectric component 401 as the high-resistance resistive films 404a and 404b using a thin film formation technique such as sputtering, reactive sputtering in a nitrogen gas atmosphere, electron-beam deposition, ion plating, or ion-assist deposition. A metal oxide film may be equally formed for the high-resistance resistive films 404a and 404b using the same thin film formation technique. In this case, however, an oxygen gas rather than a nitrogen gas is used as an atmosphere. Furthermore, a metal oxide film is formed for the high-resistance resistive films 404a and 404b using a CVD method, alcoxide application method, etc.
A carbon film is formed using deposition, sputtering, CVD method, or plasma CVD. Particularly when the high-resistance resistive films 404a and 404b are fabricated of amorphous carbon, hydrogen is contained in an atmosphere during film formation or hydrocarbon is used as a film forming gas.
The spacer electrodes 405b and 405a forming the spacer are arranged to electrically connect the high-resistance resistive films 404a and 404b to the faceplate 402 at a high voltage side and the rear plate 403 at a low voltage side. The spacer electrodes 405a and 405b have a plurality of functions as discussed below.
The high-resistance resistive films 404a and 404b serve the anti-static purpose on the surface of the spacer. If the high-resistance resistive films 404a and 404b are directly and respectively connected to the faceplate 402 and the rear plate 403 without using the spacer electrodes 405a and 405b, a large contact resistance occurs at the interface therebetween. The large contact resistance makes it difficult for a charge generated on the surface of the spacer to be quickly removed. To avoid this, the spacer electrodes 405a and 405b are arranged on the abutment faces of the spacer with the faceplate 402 and the rear plate 403.
Electrons emitted from electron emitters 407a, 407b, and 407c move along trajectories 408a, 408b and 408c in accordance with a potential distribution formed between the faceplate 402 and the rear plate 403. The potential distribution on the high-resistance resistive films 404a and 404b must be controlled over the entire extension thereof to keep the electron trajectories 408a, 408b and 408c from disturbance in the vicinity of the spacer. If the high-resistance resistive films 404a and 404b are connected to the faceplate 402 and the rear plate 403, non-uniformity in the connection state of the films and the plates occurs due to a contact resistance at the interface between the films and the plates. As a result, the potential distribution of the high-resistance resistive films 404a and 404b may be deviated from a desired one. To avoid this, the entire end faces of the spacer to be in contact with the faceplate 402 and the rear plate 403 are provided with the spacer electrodes 405b and 405a, respectively. This arrangement controls the non-uniformity in the connection state of the spacer, thereby making the potential distribution of the high-resistance resistive films 404b and 404a uniform.
Electrons emitted from the electron emitters 407a, 407b and 407c form the electron trajectories in accordance with the potential distribution generated between the faceplate 402 and the rear plate 403. Electrons emitted from the electron emitter 407a close to the spacer are subject to effect of the spacer (wiring and the position of the device). To present an image free from distortion and non-uniformity, the trajectory of emitted electrons is controlled to land the electrons in a desired position on the faceplate 402. By arranging the spacer electrodes 405b and 405a on the end faces of the spacer to be in contact with the faceplate 402 and the rear plate 403, the potential distribution in the vicinity of the spacer has the desired characteristics and the trajectory of the emitted electrons is controlled.
The ruggedized portion of the spacer extends in stripes in parallel with the faceplate 402 and the rear plate 403 (namely, perpendicular to the page of FIG. 4). The ruggedized portion of the spacer is divided into a plurality of regions having grooves which are different in average pitch and average depth thereof from region to region. In this way, equipotential lines 409 are uniformly distributed in the space between the faceplate 402 and the rear plate 403, thereby preventing the electron trajectory from being disturbed.
The construction and the manufacturing method of the image display apparatus of the present invention are discussed below.
A support frame 86 supports the glass substrate (rear plate) 81 and the faceplate 82. The support frame 86, the glass substrate (rear plate) 81, and the faceplate 82 are bonded together using frit glass, and are calcined for encapsulation at a temperature within a range of 400 to 500° C. for 10 minutes. An enclosure unit 90 thus results. The enclosure unit 90 needs to be kept in vacuum. If the above series of steps of forming the enclosure unit 90 are performed in a vacuum chamber, the enclosure unit 90 is maintained in a vacuum from the beginning. The manufacturing process is thus simplified. In the image display apparatus of the embodiment, the internal space of the enclosure unit 90 is encapsulated from the outside. Referring to
The electron emitter device 87 is a surface-conduction-type electron emitter device. An X line 88, extending in the X direction, is connected to one of a pair of electrodes of the electron emitter device 87, and a Y line Y 89, extending in the Y direction, is connected to the other of the pair of electrodes of the electron emitter device 87 not connected to the X line 88.
By arranging the spacer 100 (a support assembly) between the faceplate 82 and the glass substrate (rear plate) 81, even a large enclosure unit 90 has a sufficient strength against the atmospheric pressure.
The construction and the manufacturing process of each component of the image display apparatus of the embodiment are discussed below.
First, titanium (Ti) is deposited as an underlayer (to a thickness of 5 nm) on an electron source substrate 21, and platinum (Pt) is then deposited (to a thickness of 40 nm) on the titanium layer using a sputtering technique. A photoresist is applied, and then a series of photolithographic steps including exposure, development, and etching steps is performed to form the device electrodes 22 and 23.
After forming the device electrodes 22 and 23, Y lines 24 (lower lines), as a common wiring, are connected to one of the device electrodes 22 and 23 so that the devices are commonly connected. The material of the Y lines 24 is a silver (Ag) photo-paste ink. The silver photo-paste ink is screen-printed, dried, and then subjected to exposure and development steps, thereby becoming a predetermined pattern. The Y lines 24 are then calcined at a temperature about 480° C. The Y line 24 is about 10 μm thick and about 50 μm wide. The terminal of each Y line 24 has a wide portion at the end thereof to be used as a lead.
To isolate the upper and lower lines (X lines 26 and Y lines 24), an interlayer insulator (not shown) is arranged. The upper lines 26 (the X lines) must be electrically connected to the other of the device electrodes 22 and 23 (namely, the electrode not connected to the Y lines 24). A contact hole (not shown) is drilled in the interlayer insulator at a connection point namely, an intersection of the X line 26 and the Y line 24 beneath the X line 26. In the formation step of the interlayer insulator, photosensitive glass paste having lead oxide (PbO) as the major constituent thereof is screen-printed, and subjected to exposure and development steps. These series of steps are repeated four times. The interlayer insulator is then calcined at a temperature of about 480° C. The thickness of the interlayer insulator is about 30 μm thick, and about 150 μm wide.
A silver paste ink is screen-printed on the interlayer insulator, and is dried. These steps are repeated again for dual coating. The silver paste ink layer is then calcined at a temperature of about 480° C., thereby becoming the X (upper) lines 26. In this arrangement, the X line 26 intersects the Y line 24 with the interlayer insulator sandwiched therebetween, and is connected to the other of the device electrodes 22 and 23 through the contact hole. In a resulting panel structure of the image display device, the device electrodes 22 and 23 work as scanning electrodes. The X line 26 is about 20 μm thick. The electron source substrate 21 needs lead lines which are connected to an external driver. The lead lines are also formed in steps similar to those described above. Furthermore, terminals (not shown) to be connected to the external driver are also produced in steps similar to those described above. The electron source substrate 21 having XY matrix wiring shown in
Subsequent to the above-described process, the electron source substrate 21 is sufficiently cleaned. The surface of the electron source substrate 21 is then processed using a solution containing a water repellent material so that the surface of the electron source substrate 21 becomes hydrophobic. This process is performed to appropriately spread a film forming solution to be applied later over the device electrodes 22 and 23.
The method of forming the electron emitter device (device film) is discussed below. After producing the electron source substrate (rear plate) 21 having the above-described XY matrix wiring, an electron emitter device (device film) is formed between the device electrodes 22 and 23 using an ink-jet application method.
A palladium oxide (PdO) film is thus formed between the device electrodes 22 and 23 through the above process.
Subsequent to the formation of the device film 28, an electron emitter 27 (shown in
The waveform of the voltage used in the forming process is briefly discussed.
Referring to
Subsequent to the forming process, the electron emitter is formed on the electrically conductive thin film 104 (shown in FIG. 10). In this state, however, the electron emission efficiency of the electron emitter is extremely low. To enhance the electron emission efficiency, the electrically conductive thin film must be subjected to a process called an activation process subsequent to the forming process.
The activation process requires an appropriate level of vacuum with an organic compound present. As in the forming process, the entire electron source substrate 21 (shown in
The device and the basic characteristics of the device produced in accordance with the manufacturing method are discussed with reference to
The test instrument further includes a power supply 51 and a current meter 50. The power supply 51, connected between the device electrodes 102 and 103, measures a device voltage Vf between the device electrodes 102 and 103. The positive side of the power supply 51 is connected to the device electrode 102, and the negative side of the power supply 51 is connected to the device electrode 103 while being grounded at the same time. The current meter 50, also arranged between the device electrodes 102 and 103, measures a device current If flowing through the electrically conductive thin film 104 including the electron emitter 105.
An electrode 54 is arranged inside the vacuum container 55 at a location facing the electron emitter 105 of the device. The electrode 54 is an anode which captures electrons emitted from the electron emitter 105. The positive side of a high-voltage power supply 52 is connected to the electrode 54. The negative side of the power supply 52 is connected to ground through a current meter 53 which measures an emission current Ie from the electron emitter 105 in the device.
The vacuum container 55 further includes tools required in a typical vacuum apparatus such as a vacuum meter. The electron emitter device is thus tested under a predetermined vacuum condition. In practice, the anode 54 is supplied with a voltage of 1 kV-10 kV, and a distance between the anode 54 and the electron emitter 105 is set to be 1 mm to 8 mm.
The construction and the manufacturing method of the faceplate in the image-forming apparatus will now be discussed below.
In the encapsulation of the enclosure unit 90, the color fluorescent material 92 of each color must correspond to a respective electron emitter device. An abutment method for abutting the upper and lower plates (the rear plate and the faceplate) need to be performed to correctly align the upper and lower plates in position.
The level of vacuum of the enclosure unit 90 subsequent to the encapsulation is 10−5 Torr. To maintain this level of vacuum subsequent to the encapsulation of the enclosure unit 90, a getter process may be performed. In the getter process, a getter material mounted at a predetermined position (not shown) within the enclosure unit 90 is heated using resistance heating or high-frequency induction heating subsequent to or immediately prior to the encapsulation of the enclosure unit 90. A deposition film is thus formed. The getter typically contains barium (Ba) as the major constituent thereof. The absorption effect of the deposition film maintains the level of vacuum to within a range of 1×10−5 Torr to 1×10−7 Torr.
According to the basic characteristics of the surface-conduction type electron emitter device of this embodiment, the electrons emitted from the electron emitter are controlled by the peak value and pulse width of the pulse voltage applied between the pair of facing electrodes above a threshold voltage thereof. The intermediate value of the pulse voltage controls the current, and an intermediate gradation display is thus presented.
In the image display apparatus of this embodiment having a matrix of electron emitter devices, a line (one of the X lines) is selected by a scanning line signal and the pulse voltage is applied to each device through an information signal line (one of the Y lines). Each device, supplied with an appropriate voltage, is thus turned on. A voltage modulation or a pulse-width modulation is available as a method for modulating the electron emitter device in response to an input signal having an intermediate gradation level.
Referring to
As already discussed, tungsten (W) and germanium (Ge) were sputtered to the dielectric component 401 in a nitrogen atmosphere as high-resistance resistive films 404a and 404b. In example 1, the pitch of the grooves in the region a on the side of the faceplate 402 was 20 μm, and the pitch of the grooves in the region b on the side of the rear plate 403 was 100 μm. The widths of the region a and the region b were equal to each other. The regions were different in the average pitch and the average depth of the grooves, but it is perfectly acceptable that the regions are different from each other in one of the average pitch and the average depth of the grooves.
In the image display apparatus of example 1, the spacing between the electron emitters 407a and 407b in cross section (in a horizontal direction on the page of
Example 2 of the embodiment will now be discussed. In example 2, the spacer used in the image display apparatus is modified.
As in example 1, the spacer was segmented into regions a and b. Example 2 is different from example 1 in that the width ratio of the region a to the region b is 1:3. The pitch of the grooves in the region a was 20 μm, and the pitch of the grooves in the region b was 80 μm. The depth of the grooves in both the region a and the region b was 11 μm. The length of the spacer was 1.6 mm.
In the spacer of example 2, the average pitch of the grooves on the spacer from a half-way point up to the face plate was smaller than the average pitch of the grooves on the spacer from the half-way point down to the rear plate. Since the average pitch of the grooves in the region a was smaller than the average pitch of the grooves in the region b, the number of grooves formed on the spacer from the half-way point up to the faceplate was larger than the number of grooves formed on the spacer from the half-way point down to the rear plate.
As in example 1, a large glass base having already grooves thereon was heated, and was extended in the softened state thereof to a similarly shrunk size. As in example 1, the spacer in example 2 was coated with a high-resistance resistive film. The resistive film was deposited using a sputtering device. The sputtering device formed high-resistance resistive film using tungsten (W) and germanium (Ge) as a target in a mixture gas containing argon (Ar) and nitrogen (N2) at a flow rate of argon to nitrogen of 7:3 at a sputtering pressure of 1.0 Pa. The substrate was spaced from the targets by about 100 mm, an input power to the tungsten target was 0.55 W/cm2, and an input power to the germanium target was 2 W/cm2. A resulting thickness of the film was 200 nm.
The spacer of example 2 was used in the image display apparatus of the embodiment. No electrons were attracted in the vicinity of the spacer because of the beam repellent and attractive effect caused by the sheet resistance distribution on the surface of the spacer adjusted by the ruggedized configuration of the spacer. An excellent image was thus obtained.
Example 3 of the embodiment of the present invention will now be discussed.
Referring to
In example 3, the length ratio of the region a to the region b was 5:7, and the length of the spacer was 1.6 mm. A base was molded into the spacer substrate 1 having a ruggedized portion with grooves, and extended under heating.
The spacer of example 3 was coated with the high-resistance resistive film as in example 1 and was then used in the image display apparatus. An excellent image was presented with almost no beam position deviation occurring in the vicinity of the spacer.
Example 4 of the embodiment of the present invention is discussed.
Referring to
In the spacer of example 4, the ratio of length of the region a and the region c was 1:1 (with the length thereof equal to 180 μm). The ruggedized portion 4 having the grooves at a pitch of 80 μm was formed in each of the regions a and c. The region d was 160 μm. The length of the spacer was 1.6 mm. By increasing the length of the region d, an electric field generated in the vicinity of the spacer near the electron emitter repelled electrons in the trajectory thereof.
As in example 1, a large glass base having already grooves thereon was heated, and was extended in the softened state thereof to a similarly shrunk size. Since the area of the glass base to be processed is small, the production yield of the spacer is high.
Similar to the spacer of example 1, the spacer of example 4 was also used in the image display apparatus of the embodiment of the present invention. No electrons were attracted in the vicinity of the spacer because of the beam repellent and attractive effect caused by the sheet resistance distribution on the surface of the spacer adjusted by the ruggedized configuration of the spacer. An excellent image was thus obtained.
Example 5 of the embodiment of the present invention is discussed below.
Referring to
The spacer of example 4 was coated with the high-resistance resistive film as in example 1 and was then used in the image display apparatus. An excellent image was presented with almost no beam position deviation occurring in the vicinity of the spacer.
The electron beam apparatus containing each of the spacers of examples 1 through 5 is used as the image-forming apparatus in the above discussion. In the image-forming apparatus, each electrode works as an acceleration electrode to accelerate electrons emitted from the electron source. The image-forming apparatus irradiates a target with the electrons emitted from the cold cathode in response to an input signal, thereby presenting an image on a screen. The target is a fluorescent film. The cold cathode is a device composed of the pair of electrodes and the electrically conductive film including an electron emitter interposed therebetween, and is preferably a surface-conduction type electron emitter device. The electron source is a passive-matrix electron source which includes a plurality of cold cathodes arranged in a matrix with a plurality of lines in the row direction and a plurality of lines in the column direction. In the electron source, a plurality of lines in the row direction are arranged, each being connected to each row of a plurality of rows of cold cathodes, and control electrodes (also called grids), respectively arranged above the cold cathodes, run in the column direction.
The application of the electron beam apparatus employing the spacer of the present invention is not limited to the image-forming apparatus. The electron beam apparatus of the present invention may serve as an alternative that is substituted for a light emitting diode in an optical printer which includes a photosensitive drum and the light emitting diode.
By appropriately selecting m lines in the row direction and n lines in the column direction, not only a line optical source but also a two-dimensional optical source may be embodied. An image-forming member (the faceplate) is not limited to the above-referenced fluorescent material that directly emits light. A material that forms a latent image in accordance with static charge accumulation may also be used.
For example, the present invention may be applied to an electron microscope which uses a target, to which electrons emitted from an electron source is directed, is other than an image-forming member such as a fluorescent film. The target is not limited to any particular material in the electron beam apparatus of the present invention.
In the electron beam apparatus and the spacer of the present invention, the grooves in the ruggedized portion in the spacer extend in substantial parallel with the rear plate and the faceplate. The equipotential lines in the space between the rear plate and the faceplate run substantially parallel with the faceplate and the rear plate. The potential is thus uniformly defined in the space, and the electron trajectory is free from disturbance due to the presence of the spacer.
By modifying at least one of the depth and pitch of the grooves from region to region on the surface of the spacer, the spacer has a desired resistance distribution on the surface thereof. The use of such a spacer corrects the electron beams to a desired trajectory.
While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-021868 | Jan 2002 | JP | national |
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| 2000-311632 | Nov 2000 | JP |
| Number | Date | Country | |
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| 20030141803 A1 | Jul 2003 | US |
