JP2009063693A - Image projection screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screen which can make it possible to observe the projected image in sufficient brightness even when the light incidence angle is large and can reduce the unwanted light from the outside. <P>SOLUTION: Since the angle ω of the first reflection surface 11 and the second reflection surface 12 is set to almost 90°-ψ/2, the light flux entering aslant the first reflection surface 11 of each cell 15 is reflected on the second reflection surface 12 at the back, and directed to the front of the screen surface 10a as the light flux parallel with the first reflecting surface 11. Thus, the image projected with a large incidence angle from a short distance can be directed to the front to display by reducing the projection distance from the projector 20 to the screen 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reflective screen, and more particularly to a screen having good reflection characteristics even when the projection direction and the observation direction are greatly different.

  As a conventional screen, it has a reflecting surface formed by arranging minute concave reflecting surfaces, an optical path provided corresponding to the concave reflecting surface, and a light absorbing layer provided at the boundary of each optical path, and absorbs light. There is one in which external light is not given to an observer by absorbing external light by a layer (see Patent Document 1).

Other screens include a convex reflection surface formed in a matrix on the back side of the transparent member, and each of the reflection surfaces is adjusted in inclination according to the incident angle of the projection light (patent) Reference 2).
JP-A-4-240383 JP 2003-228133 A

  However, with regard to the former type of screen in which a light absorption layer is provided at the boundary of the optical path corresponding to the concave reflecting surface, when the projection distance is reduced and the projection is performed at a large incident angle from a short distance, vignetting of projection light, that is, unintentional Light shielding occurs and the projected image cannot be observed.

  In addition, regarding the latter type of screen in which the convex reflection surfaces are inclined and arranged in a matrix, unnecessary light from directions other than the projection light may be reflected in the same manner as the projection light.

  Accordingly, an object of the present invention is to provide a screen capable of observing a projected image with sufficient luminance even when the incident angle of the projected light is large and suppressing the intake of unnecessary light such as external light. And

  In order to solve the above problems, a screen according to the present invention includes a first reflecting surface, a second reflecting surface adjacent to the first reflecting surface, and an absorbing surface adjacent to the second reflecting surface and facing the first reflecting surface. A plurality of cells arranged along the screen surface with the second reflecting surface positioned on the rear side, and a cell disposed in at least a central region of the screen surface among the plurality of cells. When the angle formed by the incident light entering the cell and the first reflecting surface is ψ, the angle ω formed by the first reflecting surface and the second reflecting surface is approximately 90 ° −ψ / 2. Yes.

  In the above screen, since the angle ω formed by the first reflecting surface and the second reflecting surface is approximately 90 ° −ψ / 2, the incident light is inclined from the front side of the screen with respect to the first reflecting surface of the cell of interest. The light beam can be reflected by the rear second reflecting surface and emitted in the front direction of the cell as a light beam substantially parallel to the first reflecting surface. Thereby, the projection distance from the projector to the screen can be shortened, and an image projected from a short distance at a large incident angle can be displayed facing the front. Furthermore, unnecessary light from the upper side or the front side of the screen enters the absorption surface through the second reflecting surface or is emitted to the upper side of the screen, so that the unnecessary light is reflected to the front side of the screen. The possibility of being reduced can be reduced.

  In a specific aspect of the present invention, in the screen, a plurality of cells are concentrically arranged along an arc having the same incident angle of the projection light on the screen surface. In this case, cells can be arranged for each arc having a common incident angle of the incident light incident on the screen.

  In another aspect of the present invention, the plurality of cells are arranged so that the surfaces orthogonal to the first and second reflection surfaces are parallel to the projection light. In this case, the reflected light from the cell of interest can be accurately emitted toward the front.

  In yet another aspect of the present invention, in each of the cells constituting the plurality of cells, the angle ω formed by the first reflecting surface and the second reflecting surface is approximately 90 ° −ψ / 2. In this case, all the image light from each part of the screen can be emitted toward the front.

  In still another aspect of the present invention, in each cell constituting a plurality of cells, the internal space surrounded by the first and second reflection surfaces and the absorption surface is filled with a light transmissive member. In this case, the first and second reflecting surfaces can be protected while maintaining the shape of the cell by the light transmissive member, and adverse effects such as accumulation of dust in the cell can be prevented.

  In yet another aspect of the present invention, the plurality of cells are arranged at least in a direction perpendicular to the first reflection surface, the first reflection surface of the specific cell, and the absorption surface of the cell adjacent to the specific cell; Are provided on the same substrate. In this case, the cells can be arranged without gaps, and it becomes easy to maintain the positional relationship between the first reflecting surface and the absorbing surface.

  In still another aspect of the present invention, the absorbing surface is formed on an absorbing member having a predetermined thickness, and the absorbing member is thinner toward the tip at the tip on the screen surface side. In this case, it is possible to suppress the light beam incident from the front side of the screen from being blocked by the absorption surface.

In yet another aspect of the present invention, the plurality of cells are arranged at least in a direction perpendicular to the first reflecting surface, the cell window height in the adjacent direction is P, and the depth of the first reflecting surface is d. , The following relationship P = d · tanψ
Holds. In this case, the projection light entering the cell can be efficiently reflected and emitted outside the cell.

[First Embodiment]
FIG. 1 is a schematic diagram showing a projector system incorporating a screen according to a first embodiment of the present invention.

  As shown in FIG. 1, the projector system includes a screen 10 that is fixed to an indoor wall WA portion, and a projector device 20 that projects a desired image onto the screen 10. The projector device 20 is disposed below in a state of being relatively close to the screen 10. Therefore, the projection light L1 from the projector device 20 is emitted obliquely upward, and is incident on the screen surface 10a that is a plane on the front side of the screen 10 with an average large incident angle. The screen 10 emits the incident projection light L1 as image light L2 mainly in the front direction by a special reflection structure described later. The user US in front of the screen 10 can observe a bright image formed on the screen 10 with relatively little luminance unevenness.

  In a bright room, unnecessary lights L3 and L4 from, for example, the window WI and the illumination device IL are also incident on the screen 10. However, the screen 10 has a function of selectively reflecting only the projection light L1 from the projector device 20 obliquely below to the front side, and unnecessary light L3 and L4 from the window WI, the illumination device IL, etc. It is difficult to be reflected in the front direction of the screen 10 where the US is located. In other words, the black level is lowered while maintaining the white level of the projected image displayed on the screen 10 by reducing the front reflection of the unnecessary light L3 and L4 while ensuring the intensity of the image light L2.

  FIG. 2 is a conceptual diagram of the front of the screen 10, FIG. 3 is an enlarged view for explaining a cross-sectional structure in the vertical direction at the center CA of the screen 10, and FIG. 4 is one cell constituting the screen 10. It is a figure explaining the structure of AA cross section along the center of 15. FIG.

  As shown in FIGS. 2, 3, etc., the screen 10 has a structure in which a plurality of cells 15 are arranged on the front surface side in the vertical direction, that is, in the Y direction without gaps, and the back surface side is covered with a support layer 17. Each cell 15 has an upper first reflection surface 11, a rear second reflection surface 12, and a lower absorption member 13, and is sandwiched between the reflection surfaces 11, 12 and the absorption member 13. The inner space is filled with a light-transmitting resin to form the optical path portion 14, and has a substantially rectangular cross section with respect to a direction perpendicular to the AA cross section. Here, the first reflecting surface 11 and the second reflecting surface 12 are arranged so as to be adjacent to each other, and the absorbing member 13 is adjacent to the second reflecting surface 12 and faces the first reflecting surface 11. Is arranged. That is, the cross section of the first reflecting surface 11 on the top surface side, the second reflecting surface 12 on the back surface side, and the absorbing member 13 on the bottom surface side is arranged in a “U” shape as a whole.

  As shown in FIG. 2 and the like, each cell 15 has, as a reference point HP, an intersection of a perpendicular drawn from the projection lens of the projector device 20 onto the extension plane of the screen 10 and the extension plane, and the reference point HP is the center. The arc extends along a concentric circle. Thereby, the projection light L1 from the projector device 20 can be incident on the same cell 15 at the same incident angle θ. Here, although optical conditions such as the arrangement and posture of the first reflecting surface 11, the second reflecting surface 12, and the absorbing member 13 constituting each cell 15 will be described in detail later, the incident angle θ of the projection light L1 The image light L2 emitted from the screen 10 illuminated by the projection light L1 is emitted with a substantially uniform angular distribution around the normal direction of the screen 10, that is, the Z direction. It is set to be. These cells 15 are arranged flat as a whole, and constitute a screen surface 10a on which the projection light L1 having various incident angles θ from the projector device 20 is incident.

  As shown in FIG. 3, the first reflecting surface 11 constituting the cell 15 is a metal film or a multilayer film formed on the lower surface 13 c of the absorbing member 13, for example, and is incident on the incident surface 14 a of the optical path portion 14 to enter the optical path. The obliquely incident projection light L1 that has passed through the portion 14 is reflected with a small loss. Reflected light L <b> 12 reflected by the first reflecting surface 11 is emitted substantially toward the second reflecting surface 12. The first reflecting surface 11 extends in the Z direction perpendicular to the screen surface 10a, and has a belt-like curved surface corresponding to a part of a cylinder corresponding to the whole cell 15 having an arc shape.

  The second reflecting surface 12 is, for example, a metal film or a multilayer film formed on the back surface 14c of the optical path unit 14, and reflects the reflected light L12 reflected by the first reflecting surface 11 and passing through the optical path unit 14 with a small loss. To do. The image light L2 reflected by the second reflecting surface 12 travels substantially in the Z direction parallel to the first reflecting surface 11 and passes through the optical path portion 14 in the lateral direction. The second reflecting surface 12 forms an acute angle close to a right angle with respect to the first reflecting surface 11. Specifically, the second reflecting surface 12 has an equal inclination angle ψ / 2 with respect to the screen surface 10a in each optical path cross section passing through the optical path of the projection light L1 and the reference point HP. The surface 12 as a whole has a shape obtained by cutting a conical surface into a strip shape perpendicular to the axis of symmetry.

  The absorbing member 13 is a light absorbing plate bonded to the upper surface of the optical path portion 14, and is formed of, for example, a black resin material, and absorbs unnecessary light incident on the upper layer portion, that is, the absorbing surface 13a. That is, unnecessary light other than the projection light L1 from the projector device 20 installed obliquely below the screen 10 is incident on the absorption surface 13a of the absorption member 13 even if it enters the cell 15 from the incident surface 14a of the optical path portion 14. The incident light is absorbed directly or indirectly, and is hardly emitted outside the cell 15. The absorbing member 13 is disposed in parallel along the second reflecting surface 12 so as to be equidistant from the first reflecting surface 11. Further, the main body portion of the absorbing member 13 is a common substrate for supporting the absorbing surface 13a of the cell 15 to which the absorbing member 13 belongs and the first reflecting surface 11 of the cell 15 adjacent to the lower side thereof.

  The optical path unit 14 guides the projection light L1 incident on the incident surface 14a to the first reflecting surface 11, guides the reflected light L12 reflected by the first reflecting surface 11 to the second reflecting surface 12, and causes the second reflecting surface 12 to The reflected image light L2 is guided in the front direction and emitted from the incident surface 14a. At this time, the image light L2 is emitted with a substantially uniform angular distribution around the normal direction of the incident surface 14a, that is, the Z direction. This optical path part 14 has a role which protects the reflective surfaces 11 and 12 and the absorption surface 13a, and maintains an arrangement | positioning relationship. Incidentally, the incident surfaces 14a of the many optical path portions 14 constituting the screen 10 are arranged flat as a whole to constitute the screen surface 10a, and the projection light L1 having various incident angles θ from the projector device 20 is incident thereon. At the same time, the image light L2, which is reflected light, is emitted in the front direction.

  Hereinafter, with reference to FIG. 5, a method of setting the shape of the cell 15, that is, the angles and widths of the first reflection surface 11, the second reflection surface 12, the absorption surface 13 a, and the like will be described.

となる。入射面１４ａを通過した投射光Ｌ１が略全て第１反射面１１に入射する条件は、投射光Ｌ１のうち下端のものが第１反射面１１に入射することであり、第１反射面１１の奥行きすなわちセル１５の奥行きをｄとして、
Ｐ＝ｄ・ｔａｎψ … （５）
となる。つまり、セル１５の奥行きｄが決まっている場合、（５）で与えられる窓高さＰ以下に設定すれば、第１反射面１１による遮光を回避することができる。 First, the projection light L1 incident on the incident surface 14a of the optical path unit 14 at an incident angle θ is refracted by the incident surface 14a and enters the first reflecting surface 11 at a refraction angle ψ. That is, the inclination angle formed by the projection light L1 with the first reflecting surface 11 is ψ. At this time, assuming that the refractive index of the optical path portion 14 on which the projection light L1 is incident is n,
sin θ = n · sin ψ (1)
It becomes. Further, the incident angle of the projection light L1 when the projection light L1 enters the first reflecting surface 11 is 90 ° −ψ. Here, it is assumed that the vertical window height of the cell 15 is P, and that the light beam width changes from a to b when the projection light L1 enters the cell 15,
a = P · cos θ (2)
b = P · cos ψ (3)
It becomes. The above is related to the beam widths a and b.

It becomes. The condition that almost all of the projection light L1 that has passed through the incident surface 14a is incident on the first reflection surface 11 is that the lower end of the projection light L1 is incident on the first reflection surface 11, and Depth, that is, the depth of the cell 15 is d,
P = d · tanψ (5)
It becomes. That is, when the depth d of the cell 15 is determined, light shielding by the first reflecting surface 11 can be avoided by setting it to be equal to or less than the window height P given in (5).

となる。よって、画像光Ｌ２が第２反射面１２によって遮光されない条件は、第１反射面１１からの反射光Ｌ１２のうち下端のものが第２反射面１２に入射することであり、
Ｐ−ＰＥ＝ｄ・（ｔａｎψ−ｓｉｎψ） … （８）
がゼロ以上となることであるが、窓高さＰが上述の式（５）で与えられる値以下であれば、これは常に満たされる。なお、吸収部材１３の厚みは、第２反射面１２と同様に反射光Ｌ１２を遮らないことであるから、上記式（６）、（７）のＰ−ＰＥ以下とすることができる。 The reflected light L12 from the first reflecting surface 11 is incident on the second reflecting surface 12, but the angle of the second reflecting surface 12 with respect to the first reflecting surface 11 is ω = 90 ° −ψ / 2. 2. The light enters the reflection surface 12 at an incident angle ψ / 2 and is reflected at the reflection angle ψ / 2. As a result, the image light L2 reflected by the second reflecting surface 12 is emitted in the direction perpendicular to the incident surface 14a, that is, the screen surface 10a, through the optical path portion 14. Here, since the light beam width PE of the image light L2 is equal to the light beam width b of the projection light L1 before entering the second reflecting surface 12,
PE = b = d · sinψ (6)

It becomes. Therefore, the condition that the image light L2 is not shielded by the second reflecting surface 12 is that the lower end of the reflected light L12 from the first reflecting surface 11 is incident on the second reflecting surface 12,
P-PE = d · (tan ψ−sin ψ) (8)
However, this is always satisfied if the window height P is less than or equal to the value given by equation (5) above. In addition, since the thickness of the absorbing member 13 does not block the reflected light L12 similarly to the second reflecting surface 12, it can be equal to or less than P-PE in the above formulas (6) and (7).

  A front end portion 13e on the front side of the absorbing member 13 is thinner toward the screen surface 10a. Thereby, it is possible to prevent the light beam incident on the screen surface 10a from the projector device 20 from being blocked by the front end portion 13e of the absorbing member 13.

  The above is the description of the vertical cross section, but the first reflecting surface 11 and the second reflecting surface 12 are both orthogonal to each cross section of the optical path passing through the optical path of the projection light L1 and the reference point HP. In this optical path cross section, the reflecting surfaces 11 and 12 make an angle ω = 90 ° −ψ / 2. That is, the same is true for each optical path cross section, and the image light L2 can be emitted in the front direction at each part of the cell 15.

  As is clear from the above, in the design of the screen 10, for example, when the depth d of the cell 15 is constant throughout the screen 10, the incident angle θ and the refraction angle ψ become larger toward the upper side of the screen 10; The window height P is reduced on the side, and the window height P is increased on the upper side of the screen 10. On the other hand, for example, when the window height P is constant in the entire screen 10, the incident angle θ and the refraction angle ψ increase toward the upper side of the screen 10, so that the depth d is increased on the lower side of the screen 10, To reduce the depth d. By appropriately setting the depth d and the window height P of the cell 15, the projection light L1 can be efficiently extracted as the image light L2 in the front direction.

  FIG. 6 is an enlarged cross-sectional view for explaining processing of unnecessary light, and corresponds to FIG. Unnecessary light L5 incident on the screen surface 10a of the screen 10 from the upper side, that is, from the first reflecting surface 11 side of each cell 15 in an angle range of 0 to α with respect to the vertical direction, And is absorbed here. Unnecessary light L6 incident on the screen surface 10a from the upper side, that is, from the first reflecting surface 11 side in an angle range of α to α + β with respect to the vertical direction is reflected by the second reflecting surface 12 at an angle close to a right angle, It returns to the same angle range α to α + β. Unnecessary light L7 incident on the screen surface 10a from the upper side, that is, the angle range of α + β to α + β + γ with respect to the vertical direction from the first reflecting surface 11 side is reflected by the second reflecting surface 12 and then first. The light is reflected by the reflecting surface 11 and emitted downward with respect to the screen surface 10a, or is reflected by the first reflecting surface 11 next to the second reflecting surface 12 and enters the absorbing surface 13a. In summary, unnecessary light L5 to L7 incident on the screen surface 10a from the upper side is absorbed by the absorption surface 13a or emitted in directions other than the front direction of the screen surface 10a. It should be noted that it is generally considered that the unnecessary light from other than the projector device 20 incident on the screen surface 10a from the upper side has a small amount of light, and the amount emitted in the front direction of the screen surface 10a is small. That is, by adopting the structure of the cell 15 as shown in FIG. 6, unnecessary light L5 to L7 can be prevented from being emitted in the front direction of the screen surface 10a, and a reduction in contrast can be suppressed.

  Hereinafter, an example of the manufacturing method of the screen 10 of 1st Embodiment is demonstrated. For example, a thin plate-shaped absorbing member 13 is prepared in advance, the first reflecting surface 11 is formed on the lower surface 13c by vapor deposition, and the optical path portion 14 is prepared, and the second reflecting surface 12 is formed on the back surface 14c. It is formed by vapor deposition. Thereafter, the absorbing member 13 is joined to the optical path portion 14 to complete the arc-shaped cell 15. A large number of cells 15 thus formed are arranged concentrically and joined. Finally, the support layer 17 is formed behind the planarly arranged cells 15 to complete the screen 10. As another method, the support layer 17 is first formed. Next, the second reflective surface 12 is formed on the surface of the support layer 17 by vapor deposition or the like. Next, the multi-stage absorbing member 13 is formed on the support layer 17 by the same technique as the two-color molding, and the first reflecting surface 11 is formed on the lower surface 13c of the absorbing member 13 by vapor deposition or the like. Thereafter, the gaps between the absorbing members 13 are filled by the same method as the two-color molding to form the optical path portion 14. Thereby, the screen 10 is completed.

  As is apparent from the above description, in the screen 10 of the present embodiment, the angle ω formed by the first reflecting surface 11 and the second reflecting surface 12 is approximately 90 ° −ψ / 2. The light beam incident on the first reflecting surface 11 at an angle can be reflected by the rear second reflecting surface 12 and emitted as a light beam substantially parallel to the first reflecting surface 11 in the front direction of the screen surface 10a. Thereby, the projection distance from the projector device 20 to the screen 10 can be shortened, and an image projected from a short distance at a large incident angle can be displayed facing the front. Furthermore, unnecessary light from the front side or the upper side of the screen 10 enters the absorption surface 13 a through the second reflecting surface 12 or is emitted to the upper side of the screen 10. The possibility of being reflected to the front side can be reduced.

  In addition, although this invention was demonstrated according to embodiment above, this invention is not limited to the said embodiment. For example, in the screen 10 of the above-described embodiment, the cells 15 have the same shape along the AA section of FIG. 2, but may include a large number of cell elements 15 c arranged along the AA section. Yes (see FIG. 2). In this case, the planar first reflecting surface 11 and the second reflecting surface 12 can be provided for each cell element 15c. At this time, by adjusting the angle of the second reflecting surface 12, the direction of the image light from each part of the screen 10 can be gathered in the direction of the user US in the center front of the screen 10, for example. Further, the cell elements 15c constituting one cell 15 can be separated from each other by a light shielding member.

  Moreover, in the said embodiment, although the 2nd reflective surface 12 is made into the substantially flat surface, it can also be made into a lens-like concave surface or convex surface, for example. In this case, the reflected light L12 can be divergent light, and the viewing angle characteristics of the screen 10 can be corrected. In particular, when the concave surface has an appropriate curvature, light shielding by the first reflecting surface 11 and the absorbing member 13 can be prevented. When the second reflecting surface 12 is a concave surface or a convex surface, the inclination of the second reflecting surface 12 with respect to the first reflecting surface 11 is considered as a flat surface obtained by averaging the second reflecting surface 12. Similarly, the incident surface 14a of the optical path portion 14 may not be a completely flat surface but may be a lens-like concave surface or convex surface, for example. Furthermore, all or part of the second reflecting surface 12 may be a ground glass-like scattering surface. Also in this case, the viewing angle characteristic can be corrected.

  Further, the optical path portion 14 can be omitted. In this case, if the incident angle of the projection light L1 incident on the screen surface 10a from the projector device 20 is ψ, the above relational expressions (3) to (8) can be used as they are, and the depth d of the cell 15 and the window height. P can be set as appropriate.

  Moreover, in the said embodiment, although simple transparent resin is used as a material of the optical path part 14, it can also be made into what mixed the diffusing agent.

It is the schematic which shows the use condition of the projector system which concerns on this invention. It is a conceptual diagram of the front of the screen of 1st Embodiment. It is an expansion side sectional view explaining the structure of the screen of a 1st embodiment. It is a figure explaining the cross-sectional structure along the center of one cell which comprises a screen. It is an expanded side sectional view explaining the setting method of angles and widths, such as a 1st reflective surface, a 2nd reflective surface, and an absorption surface which comprise a cell. It is an expanded sectional view explaining the process of unnecessary light.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Screen, 10a ... Screen surface, 11 ... 1st reflective surface, 12 ... 2nd reflective surface, 13 ... Absorbing member, 13a ... Absorbing surface, 13e ... Tip part, 14 ... Optical path part, 14a ... Incident surface, 15 ... Cell: 17 ... support layer, 20 ... projector device, CA ... central part, HP ... reference point, L1 ... projection light, L12 ... reflected light, L2 ... image light, L3, L4 ... unnecessary light, L5-L7 ... unnecessary light

Claims (8)

A first reflecting surface; a second reflecting surface adjacent to the first reflecting surface; and an absorbing surface adjacent to the second reflecting surface and facing the first reflecting surface. With a plurality of cells arranged along the screen surface with the
Among the plurality of cells, in the cell disposed at least in the central region of the screen surface, when the angle formed by the incident light incident on the cell with the first reflective surface is ψ, the first reflective surface and the The angle ω formed by the second reflecting surface is approximately 90 ° −ψ / 2.
screen.   2. The screen according to claim 1, wherein the plurality of cells are arranged concentrically along an arc having an equal incident angle of projection light on the screen surface.   The screen according to claim 2, wherein each of the plurality of cells is arranged such that a plane orthogonal to the first and second reflection surfaces is parallel to the projection light.   The angle ω formed by the first reflecting surface and the second reflecting surface in each cell constituting the plurality of cells is approximately 90 ° −ψ / 2, respectively. The screen according to the item.   5. In each cell constituting the plurality of cells, an internal space surrounded by the first and second reflection surfaces and the absorption surface is filled with a light transmissive member. The screen according to any one of the preceding items.   The plurality of cells are arranged at least in a direction perpendicular to the first reflection surface, and the first reflection surface of a specific cell and the absorption surface of a cell adjacent to the specific cell are the same substrate The screen according to claim 1, wherein the screen is provided on the screen.   The absorption surface is formed in an absorption member having a predetermined thickness, and the absorption member is thinned toward a tip at a tip portion on the screen surface side. A screen according to claim 1. When the plurality of cells are arranged at least in a direction perpendicular to the first reflection surface, the window height of the cell in the adjacent direction is P, and the depth of the first reflection surface is d, the following: P = d · tanψ
The screen according to any one of claims 1 to 7, wherein:

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