JP2009146615A - Plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma display panel for alleviating contrast degradation due to external light. <P>SOLUTION: The plasma display panel 10 includes a front plate 200 as well as a rear-face plate 100, a barrier rib 110 zoning a discharge space between the above, phosphor layers 130 formed in a discharge cell 120, and electrodes 215 generating discharge. The front plate 200 includes a first dielectric layer 221, and a second dielectric layer 222 forming an inter-dielectric-layer interface 223 including faces slanted against a front plate surface 240 between itself and the first dielectric layer 221. The second dielectric layer 222 with a refractive index larger than that of the first dielectric layer 221 is provided at a discharge cell 120 side, the inter-dielectric-layer interface 223 is so structured to refract light incident perpendicularly upward against a normal direction of the front plate surface 240 at an angle larger than a given one in a direction of totally reflecting it at a protective layer surface 250 as an interface between the front plate 200 and the discharge space. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma display panel.

  A self-luminous display such as a plasma display or a CRT display (cathode-ray tube display) is widely used because a natural image can be obtained without dependence on a viewing angle. In particular, the plasma display is rapidly spreading because it is thin and optimal for constructing a large screen.

  However, the plasma display has a problem that it is difficult to improve the contrast of an image as compared with other display devices such as a liquid crystal display. This is because the external light that has passed through the front plate and reached the internal phosphor layer is irregularly reflected by the phosphor layer.

Thus, for example, Patent Document 1 discloses a technique for improving contrast using a filter with low transmittance. According to the technique described in Patent Document 1, a filter having a low transmittance is disposed on the side where a person who observes an image is located (hereinafter referred to as “observer side”) rather than the phosphor layer. External light passes through the filter, reaches the phosphor layer, is reflected, and then passes through the filter again to be observed. That is, the external light that reaches the phosphor layer passes through the filter at least twice in a round trip. Thereby, the amount of light returning to the viewer (hereinafter referred to as “reflected light”) is sufficiently reduced. On the other hand, the image light from the phosphor layer is observed by passing through the filter only once. Therefore, the effect of reducing the amount of light by the filter can be more strongly applied to the outside light than the image light, and the contrast in a bright place can be improved.
Japanese Patent Laid-Open No. 8-32224

  However, the technique described in Patent Document 1 has a problem that the effect of improving contrast in a bright place is small. Although it is conceivable to set the transmittance of the filter low, the image light reaching the viewer side also becomes dark, which may cause a decrease in contrast.

  This invention is made | formed in view of this point, and it aims at providing the plasma display panel which can reduce the contrast fall by the influence of external light.

  The plasma display panel of the present invention is divided by a front panel and a rear panel that are spaced apart from each other, a partition that partitions a discharge space formed between the front panel and the rear panel, and the partition. A plasma display panel comprising: a phosphor layer formed in the discharge cell; and an electrode that is arranged on each of the front plate and the back plate and generates a discharge in the discharge cell. 1 layer and a second layer forming an interface including a plane inclined with respect to the surface of the front plate between the first layer and the first layer, and the second layer Of the layers, the layer having the higher refractive index is provided on the discharge cell side, and the interface is incident vertically above the normal direction of the surface of the front plate at an angle of a predetermined angle or more. Light, the front plate and the discharge space A configuration to refract in a direction totally reflected at the boundary surface.

  According to the present invention, it is possible to refract the light incident on the front plate in the direction of total reflection at the boundary surface between the front plate and the discharge space, and the amount of light reaching the phosphor layer can be reduced. Thereby, a reduction in contrast due to the influence of external light can be reduced.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic partial cross-sectional view of a plasma display panel according to an embodiment of the present invention. FIG. 1 shows a characteristic configuration of the plasma display panel according to the present embodiment, and the illustration and description of other parts are partially omitted. FIG. 1 shows a part of a vertical section of the plasma display panel according to the present embodiment.

  Hereinafter, the “horizontal direction” and the “vertical direction” of the plasma display panel mean a horizontal direction and a vertical method when the plasma display panel is installed in a regular manner that allows correct viewing.

  As shown in FIG. 1, the plasma display panel 10 includes a back plate 100 and a front plate 200 that are spaced apart from each other and stacked in parallel. In the space between the back plate 100 and the front plate 200, a discharge space for generating plasma discharge is formed. A predetermined discharge gas mixed with helium (He), neon (Ne), xenon (Xe), argon (Ar), or the like is sealed in the discharge space.

  The back plate 100 is formed with a data electrode (not shown) covered with an insulator layer and a plurality of stripe-shaped partition walls 110 arranged in parallel with the data electrode. The discharge space described above is partitioned into a plurality of sections by the partition 110, and a plurality of discharge cells 120 serving as unit light emitting regions are formed. On the inner walls of three adjacent discharge cells 120, phosphors of red (R), green (G), and blue (B) are applied in different colors for each discharge cell to form a phosphor layer 130.

  The front plate 200 uses a transparent plate 210 made of high strain point glass as a base material, and various components for realizing a function as a plasma display panel are formed at appropriate positions on the back plate 100 side of the transparent plate 210. It has been configured. Specifically, for example, a plurality of stripe-shaped display electrodes 215 that are paired with scanning electrodes and sustain electrodes are formed on the front plate 200, and a dielectric layer 220 is formed so as to cover the display electrodes 215. A protective layer 230 is formed on the dielectric layer 220. The dielectric layer 220 is made of, for example, low melting point glass, and the protective layer 230 is made of, for example, magnesium oxide (MgO). An observer-side surface (hereinafter referred to as “front plate surface”) 240 of front plate 200 and a rear plate 100 side surface (hereinafter referred to as “protective layer surface”) 250 of front plate 200 are parallel to each other.

  The dielectric layer 220 is configured by laminating a first dielectric layer 221 and a second dielectric layer 222. The first dielectric layer 221 is disposed on the viewer side, and the second dielectric layer 222 is disposed in close contact with the first dielectric layer 221.

  The dielectric layer 220 has an inner dielectric layer interface 223 as an interface between the first dielectric layer 221 and the second dielectric layer 222. Here, as an example, a material having substantially the same refractive index as that of the protective layer 230 is used as the material of the second dielectric layer 222, and the second dielectric layer 222 is used as the material of the first dielectric layer 221. A material having a refractive index lower by about 0.2 is used.

  In the plasma display panel 10 configured as described above, when a voltage is applied between the electrodes, a discharge is generated in the discharge cell 120. For example, helium atoms in the mixed gas are excited to generate ultraviolet rays. Then, the phosphor layer 130 is excited by the ultraviolet rays, and visible light is generated.

  Here, the configuration and operation of the dielectric layer inner interface 223 will be described.

  In addition to the generated ultraviolet light, external light such as ceiling illumination light (hereinafter simply referred to as “external light”) passes through the front plate 200 and enters the fluorescent layer 130. When the amount of such extraneous light is large, the amount of light that is diffusely reflected by the phosphor layer 130 and observed on the viewer side increases, and the contrast of the image decreases.

  On the other hand, in general, when an interface having a refractive difference exists, the light beam is separated into a transmitted light beam and a reflected light beam. Further, light rays with a certain incident angle or more determined by the refractive index difference cannot be transmitted, and all of them are reflected. Therefore, it is possible to reduce the amount of external light reaching the phosphor layer 130 by providing an interface having a refractive difference on the viewer side of the phosphor layer 130. However, the light incident on the parallel plane plate is always emitted from the other surface, and this property does not change even when parallel plates having different refractive indexes are overlapped.

  Therefore, in the plasma display panel 10 according to the present exemplary embodiment, a surface (hereinafter referred to as an “inclined surface”) that is inclined with respect to the front plate surface 240 is provided at the dielectric layer inner interface 223 of the dielectric layer 220. Further, the inclined surface has an incident angle with respect to the protective layer surface 250 with respect to external light from a predetermined direction that is greater than a critical angle of the protective layer surface 250 (interface between the second dielectric layer 222 and the discharge space). It is configured to give a refractive action. As a result, the external light incident at least at a predetermined angle can be totally reflected on the observer side by the protective layer surface 250 and can be prevented from reaching the phosphor layer 130, thereby improving the contrast. .

  Further, the inclined surface of the dielectric layer inner interface 223 is formed, for example, by making the dielectric layer inner interface 223 have a mountain shape. That is, the interface 223 in the dielectric layer has a shape in which a vertical section has a number of mountain shapes, a horizontal section has a straight line, and a pair of inclined surfaces extending in a stripe shape in the horizontal direction are continuously arranged in the vertical direction. It has become. Thereby, the inclined surface of the same angle can be arrange | positioned uniformly over the panel front surface, and can be arrange | positioned in the space of the thickness direction of the front board 200. FIG.

  Further, the inclination angle of the inclined surface of the dielectric layer inner interface 223 is devised so that only the external light incident on the front plate 200 at a large incident angle is totally reflected.

  Here, conditions for totally reflecting external light incident at a predetermined angle on the protective layer surface 250 will be described.

  Hereinafter, it is assumed that the transparent plate 210 and the display electrode 215 have substantially the same refractive index as that of the first dielectric layer 221, and are handled as one body with the first dielectric layer 221, and illustration and description thereof are omitted. To do. In addition, since the horizontal cross section of the dielectric layer inner interface 223 is a straight line, regarding the light path and the configuration of the dielectric layer 220, the component in the width direction of the dielectric layer 220 is ignored.

  FIG. 2 is a diagram illustrating the relationship between the incident angles at each interface of the dielectric layer 220.

As shown in FIG. 2, the incident angle theta _in to the front plate surface 240 of the external light 300 coming from the observer side and smaller than the critical angle at the front plate surface 240 has an outer light 300 is refracted angle theta _The light enters the first dielectric layer 221 at _B. When the incident angle θ _B ′ of the external light 300 incident on the first dielectric layer 221 to the dielectric layer internal interface 223 is smaller than the critical angle at the dielectric layer internal interface 223, the external light 300 is , And enters the second dielectric layer 222 at a refraction angle θ _C ′. Furthermore, when the incident angle θ _{C of} the external light 300 incident on the second dielectric layer 222 to the protective layer surface 250 is smaller than the critical angle at the protective layer surface 250, the external light 300 has a refraction angle θ _A. Then, the light is emitted to the phosphor layer 130 side.

Here, the refractive index of the discharge space and the refractive index of air are n _A , the refractive index of the first dielectric layer 221 is n _B , the refractive index n _{C of} the second dielectric layer 221, and the dielectric layer internal interface 223. An inclination angle with respect to the front plate surface 240 and the protective layer surface 250 is θ _M.

The refraction angle θ _B when the external light 300 passes through the front plate surface 240 is expressed by the following formula (1).

The incident angle θ _B ′ when the external light 300 is incident on the front plate surface 240 is expressed by the following formula (2) using the refraction angle θ _B and the inclination angle θ _M.

The refraction angle θ _C ′ when the external light 300 passes through the front plate surface 240 is expressed by the following formula (3).

The incident angle θ _C when the external light 300 is incident on the protective layer surface 250 is expressed by the following formula (4) using the refraction angle θ _C ′ and the inclination angle θ _M.

Further, the incident angle θ _A when the external light 300 passes through the protective layer surface 250 and enters the discharge space is expressed by the following formula (5).

From the above formulas (1) to (5), the incident angle θ _A when the external light 300 passes through the protective layer surface 250 can be expressed as the following formula (6).

Further, in order for the external light 300 to be totally reflected by the protective layer surface 250, the incident angle θ _A may satisfy the following formula (7).

Therefore, from the above formulas (6) and (7), the condition for the total reflection of the external light 300 that has entered the dielectric layer 220 at the interface with the discharge space (protective layer surface 250) is as follows: ).

For example, the inclination angle θ _M of the dielectric layer inner interface 223 is determined so as to satisfy the above formula (8) in relation to the incident angle θ _B ′ of the external light 300 on the front plate surface 240 and the refractive index of each layer. . Thereby, the external light 300 incident at an angle larger than the incident angle θ _B ′ can be totally reflected by the protective layer surface 250 and not incident on the phosphor layer 130 side.

  Moreover, the relative refractive index of glass with respect to air is usually 1.5 to 2.0. Further, the ceiling illumination that affects the contrast reduction of the image is usually located in a range of about 60 degrees or more upward from the horizontal direction when viewed from the display device.

Therefore, the refractive index n _{A of} air is set to 1, the refractive index n _B of the first dielectric layer 221 is set to 1.5 corresponding to the refractive index of the most common glass, and the incident angle θ _in is 60 degrees or more. When the condition for total reflection of the external light 300 is obtained, the following equation (9) is obtained.

FIG. 3 shows the refractive index n _{C of} the second dielectric layer 221 and the minimum value (hereinafter referred to as the inclination angle θ _M of the dielectric layer internal interface 223 that satisfies the above formula (9) corresponding to the refractive index n _C. It is the figure which plotted the combination with "the minimum inclination angle". That is, FIG. 3 is a diagram showing the relationship between the refractive index n _C and the inclination angle θ _M necessary for effective total reflection to occur on the protective layer surface 250.

As shown in FIG. 3, the minimum value of the inclination angle θ _M at which effective total reflection occurs increases as the refractive index n _C decreases. The refractive index n _C of the glass that is actually possible is 2.0 or less, and the minimum value of the inclination angle θ _M at which the refractive index n _C = 2.0 is 33 degrees. Accordingly, it can be seen that a structure in which effective total reflection occurs can be realized by setting the inclination angle θ _M of the dielectric layer inner interface 223 to 33 ° or more.

  In the present embodiment, the inclination angles of the pair of inclined surfaces are inclined by 45 degrees and −45 degrees in the vertical direction with respect to front plate surface 240, respectively. Thereby, light incident at an angle of about 60 degrees or more vertically upward with respect to the normal direction of the front plate surface 240 can be refracted to an angle at which the light is totally reflected by the protective layer surface 250. Further, it is possible to prevent the image light transmitted through the dielectric layer inner interface 223 from being affected substantially in the horizontal direction (see FIG. 7).

  However, the normal direction and refractive index difference of the inclined surface to be set at the dielectric layer inner interface 223 differ depending on the direction of the external light to be noted. Here, it is assumed that the ceiling illumination light enters from an obliquely upper side of the plasma display panel 10 on the viewer side, and attention is paid to such external light incident from the upper side.

  Hereinafter, a ray tracing diagram is shown as a simulation result of the path of external light, and the refraction effect by the dielectric layer 220 will be described.

  FIG. 4 is a diagram illustrating a simulation result of external light having an incident angle of 80 degrees. 4A shows a simulation result in the dielectric layer 220 ′ in which the interface 223 ′ in the dielectric layer is a plane parallel to the front plate surface 240, and FIG. 4B shows the dielectric layer 220 in FIG. The simulation result in is shown.

  In FIG. 4, the relative refractive indices of the space on the viewer side (air), the first dielectric layer 221, the second dielectric layer 222, and the discharge space (air) with respect to air are 1.0 and 1, respectively. .52, 1.77, 1.0. That is, the refractive index of the second dielectric layer 222 is set higher by 0.25 than the refractive index of the first dielectric layer 221.

As shown in FIG. 4A, when the dielectric layer inner interface 223 ′ is a plane, the dielectric layer 220 ′ is in a state in which parallel plates having different refractive indexes are overlapped. Further, the space on the observer side and the discharge space have the same refractive index. In this state, when the incident angle θ _i0 to the front plate surface 240 is smaller than the critical angle of the front plate surface 240 and the external light 300 is incident on the dielectric layer 220 ′ without being totally reflected by the front plate surface 240, The incident angle θ _i to the layer surface 250 is also smaller than the critical angle of the protective layer surface 250. Therefore, the total reflection condition is not satisfied, and the external light 300 is always emitted from the protective layer surface 250 and reaches the phosphor layer 130 side.

On the other hand, as shown in FIG. 4B, when the dielectric layer inner interface 223 has a mountain shape, the incident angle to the protective layer surface 250 at the dielectric layer inner interface 223 with respect to the external light 300. A refractive action is given in the direction in which θ _i increases. This is because the external light 300 that has entered the first dielectric layer 221 is an inclined surface (hereinafter referred to as an “upper inclined surface”) in which the first dielectric layer 221 is on the upper side of the inclined surface of the front plate surface 240. This is because 223u faces upward from the horizontal direction.

Here, as a result of the refraction action, the incident angle θ _i of the external light 300 to the protective layer surface 250 is larger than the critical angle of the protective layer surface 250. Therefore, as shown in FIG. 4B, the external light 300 is totally reflected by the protective layer surface 250 and does not reach the phosphor layer 130 side. The externally reflected external light 300 is emitted in a direction symmetric with respect to the normal direction 225 of the front plate surface 240 with respect to the incident direction on the front plate surface 240, that is, in a lower oblique direction of the plasma display panel 10.

  FIG. 5 is a diagram showing simulation results for external light with an incident angle of 70 degrees, and corresponds to FIG. Basic conditions other than the incident angle are the same as those of the dielectric layers 220 ′ and 220 shown in FIG.

  As shown in FIG. 5A, when the dielectric layer inner interface 223 ′ is a plane, the external light 300 reaches the phosphor layer 130 side as in FIG. 4A.

On the other hand, as shown in FIG. 5B, when the dielectric layer inner interface 223 has a mountain shape, the incident angle to the protective layer surface 250 at the dielectric layer inner interface 223 with respect to the external light 300. A refractive action is given in the direction in which θ _i increases. Therefore, as in FIG. 4B, the external light 300 does not reach the phosphor layer 130 side.

  FIG. 6 is a diagram showing simulation results for external light with an incident angle of 60 degrees, and corresponds to FIGS. 4 and 5. Basic conditions other than the incident angle are the same as those of the dielectric layers 220 ′ and 220 shown in FIGS.

  As shown in FIG. 6A, when the dielectric layer inner interface 223 ′ is a plane, the external light 300 reaches the phosphor layer 130 side as in FIGS. 4A and 5A.

On the other hand, as shown in FIG. 6B, when the dielectric layer inner interface 223 has a mountain shape, the incident angle to the protective layer surface 250 at the dielectric layer inner interface 223 with respect to the external light 300. A refractive action is given in the direction in which θ _i increases. Therefore, as in FIGS. 4B and 5B, the external light 300 does not reach the phosphor layer 130 side.

  In this way, by forming the dielectric layer inner interface 223 to have a mountain shape, it is possible to give a refracting action to the external light 300 in the direction of total reflection at the protective layer surface 250. Therefore, external light incident at a large incident angle can be totally reflected by the protective layer surface 250 which is an interface between the front plate 200 and the discharge cell space.

  The interface 223 within the dielectric layer also refracts the image light, but hardly affects the sharpness of the image observed on the viewer side.

  FIG. 7 is a ray tracing diagram showing the simulation result of the path of the image light in the dielectric layer 220 in FIG. 1, and corresponds to FIG. 4 (B), FIG. 5 (B), and FIG. 6 (B). is there.

  As shown in FIG. 7, since the light emitted from the phosphor layer 130 has no directivity, the image light 400 output from the phosphor layer 130 spreads and enters the protective layer surface 250. Further, since the difference in refractive index between the first dielectric layer 221 and the second dielectric layer 222 (hereinafter simply referred to as “refractive index difference”) is only 0.25, the interface 223 within the dielectric layer is The influence of the image light 400 on the incident angle of the front plate surface 240 is small. Therefore, the range in which the image light 400 output from a certain phosphor layer 130 is transmitted through the interface within the dielectric layer and the refraction angle when transmitting through the interface within the dielectric layer are those when the interface within the dielectric layer does not exist. There is almost no difference between the case where the interface 223 in the shape of a mountain-shaped dielectric layer exists. That is, by providing the mountain-shaped inner interface 223, the contrast can be improved without reducing the sharpness of the image.

  A part of the image light 400 repeats total reflection inside the dielectric layer 220 due to the dielectric layer inner interface 223 and cannot come out from the front plate 200 to the viewer side, but the amount of light is small. is there.

  Next, the relationship between the refractive index of each layer and the incident angle of external light that is totally reflected on the protective layer surface 250 will be described. Hereinafter, the minimum angle of the incoming direction of external light that is totally reflected on the protective layer surface 250 with respect to the normal direction of the front plate surface 240 is referred to as a “minimum angle”.

  Here, for a plurality of different refractive index differences, the minimum angle of the incident angle of external light that is totally reflected on the protective layer surface 250 was examined.

  FIG. 8 is a diagram showing the minimum angle when the refractive index difference is 0.25. Specifically, the first dielectric layer 221 has a relative refractive index of 1.52 with respect to the air, and the second dielectric. This is the minimum angle when the relative refractive index of the layer 222 to air is 1.77. In this case, the minimum angle θ for total reflection of the incident angle of the external light 300 on the front plate surface 240 was 55 degrees.

  FIG. 9 is a diagram showing the minimum angle when the refractive index difference is 0.31, and specifically, the first dielectric layer 221 has a relative refractive index of 1.52 with respect to the air, and the second dielectric. This is the minimum angle when the relative refractive index of the layer 222 to air is 1.83. The minimum angle θ for total reflection of the incident angle of the external light 300 on the front plate surface 240 was 51 degrees.

  FIG. 10 is a diagram showing the minimum angle of incidence when the refractive index difference is 0.36. Specifically, the relative refractive index of the first dielectric layer 221 with respect to air is 1.52, This is the minimum angle when the relative refractive index of the dielectric layer 222 with respect to air is 1.88. In this case, the minimum angle θ for total reflection of the incident angle of the external light 300 on the front plate surface 240 was 47 degrees.

  FIG. 11 is a diagram showing the minimum angle of incidence when the refractive index difference is 0.40. Specifically, the relative refractive index of the first dielectric layer 221 with respect to air is 1.52, This is the minimum angle when the relative refractive index of the dielectric layer 222 with respect to air is 1.92. In this case, the minimum angle θ at which the incident angle of the external light 300 to the front plate surface 240 is totally reflected is 45 degrees.

  FIG. 12 is a diagram showing the minimum angle of incidence when the refractive index difference is 0.48. Specifically, the relative refractive index of the first dielectric layer 221 with respect to air is 1.52, This is the minimum angle when the relative refractive index of the dielectric layer 222 with respect to air is 2.00. In this case, the minimum angle θ for total reflection of the incident angle of the external light 300 on the front plate surface 240 was 40 degrees.

  As apparent from FIGS. 8 to 12, as the difference in refractive index increases, the minimum angle of the incident angle θ decreases, and the external light 300 satisfies the total reflection condition on the protective layer surface 250 over a wider angle range. On the other hand, when the refractive index difference is increased, the influence on the image light is also increased. Therefore, it is desirable to set the minimum refractive index difference that satisfies the total reflection condition for the range of the incoming direction of external light that should be prevented from entering the phosphor layer 130.

  As described above, according to the plasma display panel 10 according to the present exemplary embodiment, the front plate 200 has the first dielectric layer 221 and the second refractive index higher than that of the first dielectric layer 221. A dielectric layer internal interface 223 formed between the dielectric layer 222 and having a refractive index difference and including a surface inclined with respect to the front plate surface 240 is included. The dielectric layer inner interface 223 is configured to refract light incident at an angle of a predetermined angle or more vertically upward with respect to the normal direction of the front plate surface 240 in a direction in which the light is totally reflected by the protective layer surface 250. . As a result, the light incident on the front plate 200 can be refracted in the direction of total reflection at the protective layer surface 250, and the amount of light reaching the phosphor layer 130 can be reduced. That is, the brightness of the image light can be maintained while reducing the decrease in contrast due to the influence of external light. For example, even if the plasma display panel 10 is installed in a bright place, a bright image with little decrease in contrast is provided. It becomes possible.

  The dielectric layer inner interface 223 is provided inside the dielectric layer 220, and its vertical cross section has a continuous mountain shape. This makes it possible to refract the external light with a simpler structure and use a part of the dielectric layer, suppressing the increase in cost and the size of the device, and contrast caused by the influence of the external light. Reduction can be reduced. In addition, since the dielectric layer inner interface 223 is disposed near the phosphor layer that is the light emitting portion, it is possible to minimize a reduction in the sharpness of the original image light.

  The shape of the dielectric layer inner interface 223 is not limited to the above content, and it is sufficient that at least a part thereof is inclined with respect to the front plate surface 240. For example, in order to reduce the contrast decrease due to external light from the horizontal direction such as a window, the dielectric layer inner interface 223 may have a large number of mountain shapes in the horizontal cross section and a straight cross section in the vertical cross section.

  The plasma display panel according to the present invention is useful as a plasma display panel that can reduce a decrease in contrast due to the influence of external light.

1 is a schematic partial cross-sectional view of a plasma display panel according to an embodiment of the present invention. The figure which shows the relationship of the incident angle in each interface of the dielectric material layer in this Embodiment The figure which shows the relationship between the refractive index of the 2nd dielectric material layer which satisfy | fills the conditions of the total reflection of external light in this Embodiment, and the inclination angle of the interface in a dielectric material layer Ray tracing diagram of external light with an incident angle of 80 degrees in the present embodiment Ray tracing diagram of external light with an incident angle of 70 degrees in the present embodiment Ray tracing diagram of external light with an incident angle of 60 degrees in the present embodiment Ray tracing diagram of image light in this embodiment The figure which shows the minimum angle of an incident angle when the refractive index difference in this Embodiment is 0.25. The figure which shows the minimum angle of an incident angle when the refractive index difference in this Embodiment is 0.31 The figure which shows the minimum angle of an incident angle when the refractive index difference in this Embodiment is 0.36. The figure which shows the minimum angle of an incident angle when the refractive index difference in this Embodiment is 0.40. The figure which shows the minimum angle of an incident angle when the refractive index difference in this Embodiment is 0.48.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plasma display panel 100 Back plate 110 Partition 120 Discharge cell 130 Phosphor layer 200 Front plate 210 Transparent plate 215 Display electrode 220 Dielectric layer 221 First dielectric layer 222 Second dielectric layer 223 Dielectric layer inner interface 230 Protective layer 240 Front plate surface 250 Protective layer surface

Claims (5)

A front plate and a back plate that are spaced apart from each other, and
A partition wall defining a discharge space formed between the front plate and the back plate;
A phosphor layer formed in a discharge cell partitioned by the barrier ribs;
Electrodes arranged on the front plate and the back plate, respectively, to generate discharge in the discharge cells;
In a plasma display panel comprising:
The front plate is
A first layer and a second layer forming an interface including a surface inclined with respect to the surface of the front plate between the first layer and the first layer;
Of the first layer and the second layer, the layer having the higher refractive index is provided on the discharge cell side,
The interface refracts light incident at an angle of a predetermined angle or more vertically upward with respect to the normal direction of the surface of the front plate in a direction in which the light is totally reflected at the boundary surface between the front plate and the discharge space. ,
Plasma display panel. The first layer and the second layer are both dielectric layers.
The plasma display panel according to claim 1. The predetermined angle is 60 degrees or more.
The plasma display panel according to claim 1. The first layer and the second layer are made of glass,
At least a part of the inclined surface is inclined by 33 degrees or more vertically upward with respect to the normal direction of the surface of the front plate on the viewer side.
The plasma display panel according to claim 1. The interface has a mountain shape with a continuous vertical cross section,
The plasma display panel according to claim 1.

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