JP5037817B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a flat-type image display device using an electron-emitting device and a light-emitting member, and in particular, a distance between an electron source substrate on which an electron-emitting device is formed and a substrate provided with a light-emitting member. In order to hold the substrate, the invention is characterized by a spacer interposed between the two substrates.

  2. Description of the Related Art Conventionally, an image display device such as a CRT is required to have a larger screen, and the reduction in thickness and weight of the device associated with the increase in the screen has become an important issue. As such an image display device that can be reduced in thickness and weight, the present applicant has proposed a flat image display device using a surface conduction electron-emitting device. An image display device using such an electron-emitting device seals a rear plate including a plurality of electron-emitting devices and a face plate including a light-emitting member and an anode electrode through a frame member, A vacuum vessel is formed. In such an image forming apparatus, an atmospheric pressure resistant structure called a spacer is interposed between the substrates in order to prevent the substrate from being deformed or damaged due to a pressure difference between the inside and the outside of the vacuum vessel. The spacer is usually in the shape of a rectangular thin plate, and is disposed with its ends in contact with both substrates so that the surface is parallel to the normal direction of the substrates.

  The technical problem that the above spacers must satisfy is that not only the element as an atmospheric pressure resistant structure but also the presence of the spacer does not affect the trajectory of the electron beam in order to maintain the quality of the display image. is there. In general, the factor that the spacer affects the nearby emitted electrons is understood as the charging of the spacer. There are several causes for spacer charging. Basically, charge exchange is caused by the exchange of electrons with the external region due to the incidence and re-emission of electrons, and the trajectory of electrons is affected. Is to generate a charge. As a technical solution to such charge excess and deficiency, there is a method in which conductivity is imparted to the spacer to obtain a charge amount attenuation effect in terms of time. As another solution, there is a technique in which the secondary electron emission coefficient of the surface is not so large as to be 1. Specifically, the secondary electron emission coefficient of the surface material to be applied is regulated within a certain range, or the surface of the spacer is given a concavo-convex shape to reduce the amount of secondary electron emission in shape (patent) Documents 1 and 2) are known.

US Pat. No. 5,939,822 JP 2000-311632 A (USP 6809469)

  The charge that can be suppressed by applying an antistatic film to the spacer or making the surface uneven, which has been conventionally performed, is alleviated within the non-selection period of the display driving time. This charging is generated instantaneously on the surface of the spacer by electrons entering the spacer when the electron-emitting device is driven. That is, there was no cumulative charge accumulation (hereinafter, these charged charges in a short time and their charging phenomenon are referred to as short-time charged charges or short-time charges, or surface charged charges or surface charges).

  However, when irregularities are formed on the surface of the spacer, the short-term charging of the spacer is suppressed, but a change in the beam spot position is observed cumulatively as driving continues.

  An object of the present invention is to provide an image forming apparatus that suppresses cumulative charging in a spacer in which unevenness is formed on the surface and suppresses charging for a short time, thereby preventing deterioration of display characteristics due to a change in beam spot position. There is to do.

The present invention provides an electron source substrate having a plurality of electron-emitting devices and a wiring for applying a voltage to the electron-emitting devices, and an electron source substrate disposed opposite to the electron source substrate and irradiated with electrons emitted from the electron-emitting devices. An anode substrate including a light emitting member that emits light and an anode electrode; a frame that forms a vacuum container together with the electron source substrate and the anode substrate; and the electron source substrate; An image forming apparatus having a spacer disposed in contact with an anode substrate and holding a distance between both substrates,
The spacer includes an insulating base having irregularities along the normal direction of the two substrates, and a high resistance having an irregular surface on the surface of the base corresponding to the irregularities of the base with lower resistance than the insulating base. Having a membrane,
The thickness of the high resistance film located on the portion of the concavo-convex portion of the insulating substrate that intersects the normal line of the two substrates in at least a partial region of the spacer,
The following general formula (1) is satisfied.

t ≧ dp + λ (1)
t: Thickness of high resistance film (Å)
dp: primary electron penetration length (Å) = m × E ⁿ
λ: ionization electron diffusion length (Å) = 30 / Q
E: Upper limit of primary electron energy (keV)
m, n, Q: Parameters obtained experimentally from the following general formulas (2), (3), and (11) from the incident energy dependence characteristic δ (E) of the secondary electron emission characteristic of the spacer surface and the film specific gravity ρ. constant

ｍ＝５２０×Ａ（Ｚｅｆｆ）／Ｚｅｆｆ／ρ （１１）
ρ：スペーサ膜の比重（ｇ／ｃｍ³）
Ａ（Ｚｅｆｆ）：スペーサ膜の実効的原子量
Ｚｅｆｆ：スペーサ膜の実効的原子番号
Ｐ：上記δ（Ｅ）から実験的に得られるパラメータ定数

m = 520 × A (Zeff) / Zeff / ρ (11)
ρ: Specific gravity of the spacer film (g / cm ³ )
A (Zeff): Effective atomic weight of the spacer film Zeff: Effective atomic number of the spacer film P: Parameter constant obtained experimentally from the above δ (E)

  According to the present invention, both short-time charging and cumulative charging of the spacer are suppressed, and displacement of the electron beam due to the charging is prevented. As a result, a highly reliable and durable image display device that provides a good image display for a long time is provided.

  FIG. 1 schematically shows a configuration of a display panel according to an embodiment of the image forming apparatus of the present invention. FIG. 1 shows a part of the panel cut away to show the internal structure. In the figure, 12 is an electron-emitting device, 13 is a row direction wiring, 14 is a column direction wiring, and 15 is a rear plate (electron source substrate). Further, 16 is a frame member, 17 is a face plate (anode substrate), 18 is a fluorescent film, 19 is a metal back (anode electrode), 20 is a spacer, and 25 is a spacer fixing member.

In the present invention, the rear plate 15 that is the electron source substrate and the face plate 17 that is the anode substrate are sealed at the peripheral portion via the frame member 16 to form an airtight container. Since the inside of the airtight container is maintained at a vacuum of about 10 ⁻⁴ Pa, a rectangular thin plate-like spacer 20 is provided as an atmospheric pressure resistant structure in order to prevent damage due to atmospheric pressure or unexpected impact. . The end of the spacer 20 is fixed by a fixing member 25 outside the image display area.

  The rear plate 15 is formed with N × M surface conduction electron-emitting devices 12 and is arranged in a simple matrix by M row-directional wirings 13 and N column-directional wirings 14 (M, N Is a positive integer). The intersection of the row direction wiring 13 and the column direction wiring 14 is insulated by an interlayer insulating layer (not shown). In the present embodiment, a configuration in which surface conduction electron-emitting devices are arranged in a simple matrix is shown. However, the present invention is not limited to this, and is preferably applied to field emission type (FE type) or MIM type electron emission devices, and is not limited to a simple matrix arrangement.

  In the configuration of FIG. 1, the face plate 17 is provided with a fluorescent film 18 and a metal back 19 known in the field of CRT as an anode electrode. For example, the phosphor film 18 is separately applied to phosphors of three primary colors of red, green, and blue in a stripe shape, and a black conductor (black stripe) is provided between the phosphors of the respective colors. However, the arrangement of the phosphors is not limited to the arrangement of stripes, and other arrangements such as a delta arrangement may be used according to the arrangement of the electron sources.

  FIG. 2 shows a partial cross-sectional view of the spacer 20. Moreover, the spacer 20 used by this invention comprises an uneven | corrugated shape in the side surface from a viewpoint of suppressing secondary electron emission. The spacer 20 is coated with a high resistance film 32 that roughly reflects the irregularities on the surface of the insulating base 31 having irregularities along the normal direction (that is, the Z direction) of the face plate 17 and the rear plate 15. Has been. The resistance value of the high resistance film 32 is lower than the resistance value of the insulating substrate 31.

  The spacer 20 used in the present invention is disposed in parallel to the row-direction wiring 13 that is a cathode electrode, and is electrically connected to the row-direction wiring 13 and the metal back 19 that is an anode electrode.

  The structural features and operation of the spacer 20 used in the present invention will be described below.

  In the present invention, the thickness of the high-resistance film on the uneven slope intersecting with the normal direction (Z direction in FIG. 2) of the two substrates in at least a part of the insulating base surface of the spacer ( t) satisfies the following general formula (1).

t ≧ dp + λ (1)
t: Thickness of high resistance film (Å)
dp: primary electron penetration length (Å) = m × E ⁿ
λ: ionization electron diffusion length (Å) = 30 / Q
E: Upper limit of primary electron energy (keV)
m, n, Q: Parameters obtained experimentally from the following general formulas (2), (3), and (11) from the incident energy dependence characteristic δ (E) of the secondary electron emission characteristic of the spacer surface and the film specific gravity ρ. constant

ｍ＝５２０×Ａ（Ｚｅｆｆ）／Ｚｅｆｆ／ρ （１１）
ρ：スペーサ膜の比重（ｇ／ｃｍ³）
Ａ（Ｚｅｆｆ）：スペーサ膜の実効的原子量
Ｚｅｆｆ：スペーサ膜の実効的原子番号
Ｐ：上記δ（Ｅ）から実験的に得られるパラメータ定数

m = 520 × A (Zeff) / Zeff / ρ (11)
ρ: Specific gravity of the spacer film (g / cm ³ )
A (Zeff): Effective atomic weight of the spacer film Zeff: Effective atomic number of the spacer film P: Parameter constant obtained experimentally from the above δ (E)

  According to the study of the present inventor, when the display device is driven for a long time, the charging phenomenon on the surface of the spacer 20 having irregularities on the surface is formed on the spacer surface and the penetration length (dp) of primary electrons incident on the spacer. It was found that this was related to the film thickness of the high resistance film 32.

This is shown in FIG. Sample A in the graph has a sheet resistance of 2 × 10 ^{12 to} 3 × 10 ¹² Ω / □ at 25 ° C. on an insulating substrate (glass PD200) on which unevenness with an uneven pitch of 30 μm and a depth of 10 μm is formed. In this way, a high resistance film is coated with a single layer. In Sample B, a first layer having a sheet resistance of 3 × 10 ¹² Ω / □ at a film thickness of 100 nm is formed on the same insulating substrate at 25 ° C., and the resistance is three orders of magnitude higher than that of the first layer. A second layer having a sheet resistance of 0.5 × 10 ¹⁶ to 1 × 10 ¹⁶ Ω / □ at 25 ° C. is formed. Hereinafter, the first layer may be referred to as a potential regulating layer. The vertical axis in the figure represents the beam position after 10 hours of continuous driving at a video rate of 60 Hz at an anode voltage of 10 kV. The beam position is a beam position when a minimum observation electron current density is given. The minimum observational electron current density is the amount of electron dose corresponding to the minimum pulse width and the minimum pulse height during normal device driving. The horizontal axis indicates the film thickness of the high resistance film. The film thickness of the high resistance film in Sample B is the film thickness of the second layer of high resistance film.

  In FIG. 3, when the beam position is in the range of −5 μm to 5 μm as a level with improved charging characteristics (background level), it can be seen that the displacement of the beam position can be prevented with a certain film thickness. The sample A having a single layer structure requires a film thickness of 1.2 μm or more in order to obtain sufficient characteristics. On the other hand, it is suggested that the laminated sample B requires a small thickness of the high resistance film (second layer). However, also in the sample B, when the film thickness of the second layer becomes too large, it is considered that the carrier constrained by the second layer works as a charge and affects the beam position. This is probably because the time constant of charge relaxation of the second layer is high (long).

  The present inventor determines an appropriate film thickness of the second layer (upper layer) in a spacer in which the lower layer such as the above-mentioned sample B group functions as a potential regulating layer and the upper layer functions as an electron intrusion suppression layer. It was judged that the following were related as elements.

[Electron penetration length, electron penetration mode, and carrier generation center of gravity]
As shown in FIG. 2, in the spacer 20 in which the surface of the insulating base 31 is coated with the high resistance film 32, the electrons entering the high resistance film 32 are generally energy deactivation described by the following general formula (5). Through the process, it loses energy and finally stops. The distance from the surface of the high resistance film 32 to the position where electrons stop is expressed by the primary electron penetration length (dp).

  Where n ≧ 1

  In the general formula (5), n = 1 corresponds to an inelastic scattering state, and a certain energy is lost without depending on the penetration length (dp) of the primary electrons. Moreover, in n> 1, it shows that the deactivation energy of the electron per unit depth is so large that it approaches the terminal of the penetration | invasion process of an electron.

When the differential equation (5) is given with E (x) = 0 as the boundary condition at the penetration length dp = x, E (x) can be described algebraically and is expressed as follows.
E (x) ⁿ = An (d−x) (6)
E (x) ^n-1 = {An (d−x)} ^{(n−1) / n} (7)

  Therefore, the following general formula (8) is obtained from the general formula (5) and the general formula (7).

  When the required energy in the production process of secondary electrons in the medium is ξ, the carrier generation density distribution n (x) in the medium per unit depth is expressed by the following general formula (9).

  FIG. 4 shows the carrier generation density distribution represented by the general formula (9). FIG. 4 is a depth dependent profile of typical internally generated carrier concentration from n = 1 to n = 2. In FIG. 4, only when n = 1, the number of electrons generated per unit depth is constant, and the energy deactivation mode at the time of collision between the medium and the electrons is an inelastic scattering mode. When n> 1, the number of electrons generated per unit depth has a distribution with respect to the depth. The maximum n value on the definition is 2. At this time, the energy deactivation mode at the time of collision between the medium and the electrons is an elastic scattering mode.

  The n value of the general formula (9) is determined by measuring the primary electron energy dependence characteristic [δ (E)] of the secondary electron emission coefficient described later. Generally, a high resistance film material used for a spacer takes a value between n = 1 and 2 and takes an energy deactivation process in which elastic scattering and inelastic scattering are mixed. That is, it is expected that a profile having a peak in the vicinity of the intrusion termination portion and a higher generated carrier concentration in the deep portion, such as a profile of n = 1.5 or n = 2 in FIG.

  The primary electron penetration length (dp) can be described by the following general formula (10).

  Both the n value and the value of the An product in the general formula (10) can be determined by measuring the primary electron energy dependency characteristic [δ (E)] of the secondary electron emission coefficient described later. This determined penetration depth (dp) gives the generation region peak or centroid of carriers generated inside the high-resistance film.

[Effect of electron diffusion distance and potential regulating layer]
Most of the carriers generated inside recombine with nearby electrons or holes and do not contribute to the charging of the spacer. However, a part of the carrier exists for a certain time without recombination and causes charging. The duration of charging depends on a time constant determined by the capacitance component C and the resistance component R of the film on the spacer surface. That is, among the primary electron intrusion regions, the position of the intrusion termination portion is particularly important for suppressing long-term charging. Considering the case where the spacer is formed by the insulating base 31 and the high resistance film 32 as shown in FIG. 2, the penetration length (dp) has a long time constant (on the order of seconds). It is not preferable to reach the maximum. In other words, it is not preferable that the primary electrons reach the insulating substrate. Further, since the ionized electrons are further diffused from the intrusion termination portion, the film thickness (t) of the high resistance film 32 needs to satisfy the following relationship in consideration of the diffusion length (λ).

    t ≧ prime electron penetration length (dp) + ionization electron diffusion length (λ) (1)

  In the present invention, the film thickness (t) of the high resistance film 32 is, as shown in FIG. 2, at a portion on the uneven slope of the insulating substrate 31 that intersects the normal direction (Z direction) of the substrate. The thickness in the normal direction of the slope is said. The same applies to the thickness (s) of the high resistance region described later. This is in consideration of the fact that the film thickness on the uneven slope tends to be thinner than other parts during film formation. The film thickness (t) condition is preferably satisfied in an area of at least 50% in the normal direction of the substrate from the end on the face plate side. This is because the effect of spacer charging due to primary electron penetration is strong on the face plate side.

Further, as described above with reference to FIG. 3, the function-separated film configuration is preferable in order to define the spacer potential. Therefore, preferably, a low-resistance region for regulating potential and a high-resistance region for suppressing electron penetration are formed on the insulating substrate. At this time, the film thickness (s) of the high resistance region for suppressing electron penetration is determined by taking into account the diffusion length (λ) of ionization electrons in the high resistance region [the penetration length of primary electrons (dp) + the diffusion of ionization electrons. It can be seen that it is preferable to set the film thickness corresponding to [length (λ)] as the lower limit. That is,
dp + λ ≧ s (4)
It is. Since the diffusion length (λ) of the ionized electrons reaches the low resistance region, the ionized electrons are quickly relaxed in the low resistance region, and charged charges can be suppressed. That is, the probability that ionized electrons remain in the high resistance region can be reduced. More preferably, s> dp.

  The ionization electron diffusion length (λ) can be described by its explanatory parameter Q (absorption coefficient) by measuring the primary electron energy dependency characteristic δ (E) of the secondary electron emission coefficient described later. According to the study of the present inventor, it has been found that the diffusion length should be 30 times the distance (Å) given by the reciprocal of Q.

[Measurement Method of Secondary Electron Emission Coefficient (δ) and Its Incident Energy Dependent Characteristic δ (E)]
Here, the secondary electron emission coefficient (δ) and the incident energy dependence characteristic [δ (E)] of the secondary electron emission coefficient are measured as follows.

First, as the secondary electron emission coefficient (δ), a general-purpose scanning electron microscope (SEM) equipped with an electron ammeter is used. The primary electron current uses a Faraday cup. The amount of secondary electron current emitted is measured using a current amplifier using a collector (MCP or the like can be used) as a detector. Further, it may be obtained from the sample current and the primary electron current using the relationship of the continuity rule of the sample current passing through the sample portion, the primary electron current, and the emission secondary electron current. In general, when observing the amount of secondary electron current emitted from a medium whose volume resistance is 1 × 10 ⁴ Ωcm or more, when the amount of secondary electron current is positive due to local charging in the vicinity of the primary electron irradiation region May have a measurement error as an undervalue, an overvalue in the case of negative charging. For this reason, it is desirable that primary electrons having a pulse width of the order of msec are incident on the sample to eliminate the influence of charging due to continuous irradiation. In the present invention, a pulse width of 10 msec was used for actual measurement.

  The incident electron energy dependency characteristic [δ (E)] of the secondary electron emission coefficient was performed under the condition that the incident angle of the primary electrons was 90 °, that is, the normal incident condition. When the 90 ° incident angle condition cannot be obtained due to the shape of the object to be measured, the Q parameter in the general formula (2) is replaced with Q cos θ (θ: incident angle) as a regression function. This is possible by actually measuring at a constant incident angle θ. A method for determining the Q value, m value, and n value necessary for describing the characteristics of the spacer high resistance film used in the present invention will be described below.

In the general formula (2), the incident energy dependence characteristic of the secondary electron emission coefficient is determined by the least squares method with the indefinite constants P, Q, m, and n values using the incident energy E as a variable. That is, using at least four sets of actual measurement results (δi value, Ei value) (i value = 1, 2, 3, 4) having different incident energies from each other, the general expression (2) is converted into a regression analysis model. When regression analysis is performed as an equation, indefinite constants P, Q, m, and n can be determined. The measurement points of incident energy at the time of actual measurement are four indefinite parameters, so at least four are necessary. Generally, the more measurement points, the less the error associated with the regression processing of the decision parameters, 6-10 points. The degree is appropriate. At this time, it is desirable to set many measurement conditions in an energy range of about 0 to 3 keV where the characteristic change with respect to the incident electron energy is large, and to include incident electron energy corresponding to the acceleration voltage of the image forming apparatus in the measurement range. . The degree of vacuum was 10 ⁻⁵ Pa or less, and the measurement was performed at room temperature (25 ° C.).

  FIG. 5 shows a measurement example of the incident energy dependency characteristic [δ (E)] of the secondary electron emission coefficient, and numerical examples of parameters obtained therefrom.

Examples of the insulating base of the spacer used in the present invention include quartz glass, glass with reduced impurity content such as Na, ceramic members such as soda lime glass, alumina, etc., and the coefficient of thermal expansion forms an airtight container. Those close to the member are preferred. The high resistance film coated on the insulating substrate has a sheet resistance value of 1 × 10 ⁸ to 1 × 10 ^{15 in} both cases of a single layer and a low resistance region and a high resistance region. It is preferable to select in the range of Ω / □. In addition, when providing a low resistance area | region and a high resistance area | region, it is preferable to comprise so that the resistance value of a high resistance area | region may become 10 times or more of the resistance value of a low resistance area | region. As a material for such a high resistance film, a metal element having an atomic number of 37 (rubidium) or more is contained at 3 atomic% or more, or an oxide or nitride of an element having an atomic number of 32 (germanium) or more is a main component. What is contained as is preferable. Specifically, W (tungsten), Pt (platinum), Au (gold), Pd (palladium), Ru (ruthenium), or the like is preferably used as the former metal having an atomic number of 37 or more. As the oxide or nitride of the latter element having an atomic number of 32 or more, Ge ₃ N ₄ (germanium nitride), SnO ₂ (tin oxide) or the like is preferably used. However, the stoichiometric composition ratio is not limited to the above value. The high resistance film can be formed by any of sputtering, vacuum deposition, wet printing, spraying, or dipping. In the present invention, a higher resistance film such as an insulating carbon film is formed on the surface side of the high resistance film having the low resistance region and the high resistance region, so that the escape probability of secondary electrons is increased. Suppression (that is, reduction of the secondary electron emission coefficient) may be achieved.

  The thickness of the high resistance film is measured by the following method. That is, the cut surface cut out perpendicular to the spacer surface is exposed. At the cut surface, the film thickness can be measured by a cross-sectional SEM. When evaluating by cross-sectional SEM, the local charge-up by the insulation of a sample can be suppressed by providing the sputter | spatter coating of a metal thin film as pre-processing.

  In the present invention, the unevenness on the surface of the insulating base of the spacer needs to be at least a shape along the normal direction (Z direction) of the substrate. This is in a direction that reduces the incident angle dependence of the secondary electron emission coefficient for both the trajectory of the electron beam from the electron source and the trajectory of the electron beam reflected by the anode electrode. Any shape is acceptable. Therefore, although a line shape parallel to the substrate is preferably used, it may be formed along the X direction in addition to the direction. In this case, the unevenness is formed in a dot shape on the spacer surface. The average period of the irregularities is preferably 100 μm or less, and more preferably 10 μm or less. Moreover, the average roughness is preferably 0.1 μm or more and 100 μm or less, and more preferably the average roughness is 1 μm or more and 10 μm or less.

  The cross-sectional shape of the unevenness on the spacer surface according to the present invention is not particularly limited, and a trapezoid, a rectangle, a triangle, or the like can be used as appropriate in addition to the waveform shown in FIG. Furthermore, a plurality of shapes may be used in combination. Further, the fine particles may be constituted by being roughened by being dispersed and contained in the binder matrix. Further, porous glass or porous ceramic may be used.

  The spacer according to the present invention is in contact with the anode electrode and the electron source, and a conductive film may be additionally provided on the contact surface.

  The spacer shown in FIG. 1 has a rectangular thin plate shape and is preferably used in the present invention. However, in the present invention, the spacer is not limited to the shape, and a columnar shape or the like can be appropriately selected within a range where an equivalent effect can be obtained. it can.

Example 1
The spacer used in the present invention was produced as follows.

  Asahi Glass Co., Ltd. PD200 substrate was used as a base material to prepare an insulating substrate for the spacer, which was shaped by the heat stretching method. The shape of the substrate is 1.7 mm × 0.18 mm × 820 mm, and convex portions having a substantially trapezoidal cross-sectional shape and an average height of 8 μm are formed on a 820 mm × 1.7 mm surface (hereinafter referred to as a side surface) with a pitch of 30 μm. Has been. In addition, a surface of 0.18 mm × 820 mm (hereinafter referred to as a contact surface) has a planar shape because it contacts the cathode (upper wiring) and the anode (metal back). The corner between the side surface and the bottom surface has a round shape in order to minimize chipping, and its curvature radius is 5 μm. In addition, the round shape of the said unevenness | corrugation and a corner | angular part is extended | stretched so that the shape of the base material glass before extending | stretching may be maintained. As a result, in the assembled state, each shape is formed so as to be extended in a direction parallel to the face plate and the rear plate.

  Cleaning step: After performing ultrasonic cleaning and rinsing with pure water, IPA (isopropyl alcohol), and acetone, the substrate after cleaning was obtained through hot air drying. Next, a high resistance film was formed on four surfaces excluding the 1.7 mm × 0.18 mm surface.

High resistance film formation process:
A high resistance film was formed on the insulating substrate by RF sputtering. The high resistance film 1 was formed on the four surfaces of the side surface and the contact surface, and the high resistance film 2 was further formed on the two side surfaces to form a laminated high resistance film coated spacer. The film was formed such that the resistance value of the high resistance film 2 was 10 times higher than that of the high resistance film 1. The high resistance film 1 was formed of PtAlN having a thickness of 40 nm so that the sheet resistance after film formation was 2.5 × 10 ¹² Ω / □ at 25 ° C.

Table 1 shows the measured values of the resistance value and film thickness at 25 ° C. of the high resistance film 2 used in this example, and the parameters relating to the interaction between electrons and the high resistance film 2. Here, the parameter Q is an electron absorption coefficient 媒質⁻¹ = × 10 ¹⁰ m ⁻¹ in the medium, m is a constant proportional to the reciprocal of the electron density, and n is a parameter describing the penetration mode of the penetration primary electrons in the medium. n.

  In the measurement, the high-resistance film 2 having a thickness of 10 μm was formed on a smooth substrate, and the primary electron energy dependency characteristic [δ (E)] of the secondary electron emission coefficient was measured by the measurement method described above.

  Table 2 shows the structure of the spacer of this example in which each high resistance film 2 in Table 1 is formed on the high resistance film 1 on the side surface of the insulating substrate.

  In Table 2, the primary electron penetration length dp is determined by m, n, and E (primary energy upper limit = anode acceleration voltage Va [V]).

dp [Å] = m × Va n

  Using the spacers 1-1 to 1-5 of this example, an image forming apparatus having the configuration shown in FIG. 1 was manufactured and driven. As a result, no positional deviation of the electron beam in the vicinity of the spacer was observed even when the device using any spacer was driven for a long time. Further, it was confirmed that the residual charge was effectively suppressed even in the deep region of the high resistance film on the spacer surface, and the potential regulation by the current flowing through the spacer was established.

  In this example, the characteristic values (for example, electric resistance and composition ratio) of the high resistance film 1 and the high resistance film 2 are formed discontinuously in the film thickness direction. However, the present invention is not limited to this, and it is formed so as to have a continuous characteristic value in the film thickness direction so that the relationship between the effective electron penetration distance and the film thickness in consideration of the electron diffusion length (λ) is equivalently expressed. It is also possible. In that case, a virtual boundary where the effective sheet resistance is equivalent when the internal sheet resistance is 0.1 times the sheet resistance of the external region may be handled as the film thickness of the high resistance film 2.

  Further, the method for forming the high resistance film is not particularly limited to the coating process such as printing and ion doping to the insulating substrate.

(Example 2)
Example 1 is the same as Example 1, except that electrodes made of Pt were formed on the bottom surface of the spacer (that is, two surfaces of 0.18 mm × 820 mm), and the image display device was configured and driven. . As a result, even when driven for a long time, no displacement of the electron beam in the vicinity of the spacer was observed, and it was confirmed that the potential regulation by the current field of the spacer was established even in the deep region of the high resistance film on the spacer surface. It was done.

(Example 3)
A spacer was produced in the same manner as in Example 1 except that amorphous carbon having a further insulating property (volume resistance at 25 ° C .: 3 × 10 ¹¹ Ωcm or more) was laminated on the surface of the high resistance film in the same manner as in Example 1, and an image forming apparatus was manufactured. Configured. As a result, no positional deviation of the electron beam was observed even when the device was driven for a long time, and it was confirmed that the potential regulation by the current field of the spacer was established even in the deep region of the high resistance film on the spacer surface. It was.

The film density of the WGeN film of the high resistance film 2 of the spacers 1-1 and 1-4 in Example 1 is 16 g / cm ³ , and the film density of the first high resistance film 1 (PtAlN film) is 9. It was 1 g / cm ³ . The film density was determined by Rutherford backscattering spectroscopy (RBS method). Based on the film density, that is, specific gravity, among the characteristic parameters obtained by the primary electron energy dependence characteristic [δ (E)] of the secondary electron emission coefficient, m value is determined in advance, and other parameters are obtained. It was determined.

  A method for determining the parameter m value in the secondary electron emission coefficient energy-dependent characteristic obtained from the film density information of the spacer film will be described below.

  As energy dependence characteristics of the secondary electron emission coefficient, measurement is performed with five or more energy values within a range including a peak on the low energy side, and regression analysis is performed using the general formula (2) as a regression analysis model formula. In the regression analysis, a parameter m value obtained in advance is used.

Here, K.A. I. Grais, A .; M.M. By J. Bastawros. Appl. Phys. 53,5293 (1982) to the presently disclosed and are in Bronshtein range-energy relation dp (Å) = 520 × A (Zeff) / ρ / Zeff × E n
And dp mentioned above: primary electron penetration length (Å) = m × E ⁿ
Thus, the m value can be described by the film density. Therefore, from the ratio of the effective atomic weight A (Zeff) obtained from the composition ratio of the film and the effective atomic number Zeff,
m = 520 × A (Zeff) / Zeff / ρ (11)
From the relationship, the parameter m value was obtained.

  In the present invention, it is more preferable to use a film having a higher specific gravity than the high resistance film 1 as the high resistance film 2. As a result, the effective electron penetration length is suppressed, the process tact is increased without increasing the required film thickness of the high resistance film 2, and the residual stress of the film on the insulating substrate by increasing the film thickness. Can be suppressed to prevent film peeling and the like.

  In Rutherford Backscattering Spectroscopy (RBS), there are cases where there are restrictions such as the support substrate being limited to silicon wear. Therefore, when Rutherford backscattering spectroscopy (RBS) cannot be obtained, the film density may be determined from other composition analysis, film weighing and film thickness information.

  In this example, when forming a high resistance film that has been confirmed to have a high electron density in the second layer (outside from which the primary electrons enter from the first layer where the potential can be defined), The film thickness can be reduced, and the manufacturing time and tact time can be suppressed. In this example, compared to the production time of the second layer in 1-5 of Example 1, the efficiency of 1-1 can be increased by 1.5 times in film thickness and approximately 3 times in film formation speed. The film formation time of the layer could be suppressed to 22%.

In view of the above, the high resistance film 2 preferably contains 3 % atomic or more of a metal element having an atomic number of 37 or more, or contains an oxide or nitride of an element having an atomic number of 32 or more as a main component.

  Further, the high resistance film 2 of this example is an elastic scattering type intrusion mode in which n is 1.5 or more and 2 or less at an anode applied voltage (acceleration voltage) Va = 11 kV during operation. Therefore, the interaction between the penetrating electrons and the high resistance film of the spacer is more active at the deep part of the penetrating depth. Therefore, most of the ionized carriers can be efficiently neutralized in the internal high resistance film 1 having a relatively low resistance.

1 is a perspective view schematically showing a configuration of a display panel as an example of an image forming apparatus of the present invention. It is a partial cross-section schematic diagram of an example of the spacer used for this invention. It is a figure which shows the relationship between the primary electron penetration | invasion length and the film thickness of the high resistance film | membrane of the spacer surface. It is a figure which shows the production | generation density distribution of the carrier in a medium. It is a figure which shows the example of a measurement of the incident energy dependence characteristic [delta (E)] of the secondary electron emission characteristic concerning this invention.

Explanation of symbols

12 Electron emitter 13 Upper wiring 14 Lower wiring 15 Rear plate (electron source substrate)
16 Frame material 17 Face plate (Anode substrate)
18 Fluorescent film 19 Metal back (Anode electrode)
20 Spacer 25 Fixing member 31 Insulating substrate 32 High resistance film

Claims (5)

An electron source substrate having a plurality of electron-emitting devices and wiring for applying a voltage to the electron-emitting devices, and a light-emitting member that is disposed opposite to the electron source substrate and emits light by irradiation of electrons emitted from the electron-emitting devices An anode substrate including a cathode electrode and an anode electrode, a frame that forms a vacuum container together with the electron source substrate and the anode substrate, interposed between peripheral edges of the electron source substrate and the anode substrate, and the electron source substrate and the anode substrate. An image forming apparatus having a spacer arranged in contact with each other and holding a distance between both substrates,
The spacer includes an insulating base having irregularities along the normal direction of the two substrates, and a high resistance having an irregular surface on the surface of the base corresponding to the irregularities of the base with lower resistance than the insulating base. Having a membrane,
The thickness of the high resistance film located on the portion of the concavo-convex portion of the insulating substrate that intersects the normal line of the two substrates in at least a part of the spacer satisfies the following general formula (1). An image forming apparatus.
t ≧ dp + λ (1)
t: Thickness of high resistance film (Å)
dp: primary electron penetration length (Å) = m × E ⁿ
λ: ionization electron diffusion length (Å) = 30 / Q
E: Upper limit of primary electron energy (keV)
m, n, Q: Parameters obtained experimentally from the following general formulas (2), (3), and (11) from the incident energy dependence characteristic δ (E) of the secondary electron emission characteristic of the spacer surface and the film specific gravity ρ. constant

m = 520 × A (Zeff) / Zeff / ρ (11)
ρ: Specific gravity of the spacer film (g / cm ³ )
A (Zeff): Effective atomic weight of the spacer film Zeff: Effective atomic number of the spacer film P: Parameter constant obtained experimentally from the above δ (E) 2. The image formation according to claim 1, wherein an area satisfying the general formula (1) is an area of 50% or more with respect to a height of the spacer in a normal direction of the anode substrate from an end portion in contact with the anode substrate of the spacer. apparatus. The high-resistance film of the spacer has at least two regions, a low-resistance region located on the substrate side and a high-resistance region located on the outside, and intersects the normal lines of the two substrates in the uneven portion of the insulating substrate. The image forming apparatus according to claim 1, wherein the thickness (s) of the high resistance region located on the portion to be satisfied satisfies the following general formula (4).
dp + λ ≧ s (4) The image according to claim 1, wherein the high resistance film of the spacer contains 3 atomic% or more of a metal element having an atomic number of 37 or more, or contains an oxide or nitride of an element having an atomic number of 32 or more as a main component. Forming equipment. The image forming apparatus according to claim 1, wherein a sheet resistance value of the high resistance film of the spacer is 1 × 10 ⁸ Ω / □ or more and 1 × 10 ¹⁵ Ω / □ or less.

Images