Panel for a room system and clean room system
The V-shaped collar design with an undercut area for the seal addresses sealing challenges in cleanroom panels by ensuring a reliable, continuous seal and simplifying installation, enhancing flexibility and efficiency in cleanroom construction.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- RITTERWAND & METALL SYSTBAU
- Filing Date
- 2025-11-06
- Publication Date
- 2026-05-15
AI Technical Summary
Existing cleanroom panels face challenges in achieving reliable and flexible sealing against frame structures due to issues with seal deformation, displacement, and assembly complexity, particularly when using gravity-based sealing methods.
The panels incorporate a V-shaped collar design with an undercut area for the seal, allowing it to be applied during manufacturing, reducing assembly steps and ensuring a reliable, continuous seal by minimizing seal deformation and displacement during installation.
The V-shaped collar design provides a seamless, reliable seal against frame components, simplifies installation, and accommodates manufacturing tolerances, while reducing the risk of ventilation paths and ensuring effective sealing in various panel configurations.
Smart Images

Figure EP2025082163_15052026_PF_FP_ABST
Abstract
Description
[0001] Panel for a room system and cleanroom system
[0002]
[0001] The present invention relates to a panel for a room system and its use, as well as a cleanroom system with such a panel.
[0003]
[0002] In a room, such as a cleanroom, the concentration of aerosols and particles must be kept as low as possible. The walls and ceilings of such a room must therefore be sealed in a suitable manner to prevent the ingress of aerosols and particles from outside. To enable the most flexible construction possible, which meets the different requirements for the geometry of the cleanroom, wall and ceiling panels are typically used. These serve as surfaces of a cleanroom wall or cleanroom ceiling or are combined modularly, optionally using additional components, to provide a wall or ceiling with a desired geometry. Accordingly, sufficient sealing against a counterpart arranged there, such as a stud wall or ceiling, is particularly important at the sides of the panels.a frame construction or another wall or ceiling panel to ensure the cleanroom wall construction.
[0004]
[0003] CN 201087512 Y discloses a suspended panel structure for ceilings. The known ceiling panels are provided with a downwardly open groove on their perimeter, in which a sealing strip is arranged. The groove is arc-shaped or has a V-shaped tip. The one-piece construction of the panel results in increased rigidity and simplifies installation. A seal between the ceiling panel and the adjacent components is provided by gravity.
[0004] DE 20 2005 008 334 Ul discloses a cleanroom constructed from a supporting frame and panels detachably attached to it. Each panel has projecting folded edges, by means of which it is attached to a stand together with an adjacent panel by means of screw connections. For sealing, a gasket is inserted under the screw connection during installation and clamped there.
[0005]
[0005] Against this background, a panel with the features of claim 1 and a cleanroom system with the features of claim 14 are proposed according to the invention. Advantageous further developments are the subject of the dependent claims.
[0006]
[0006] The invention relates to a panel for a wall or a (suspended) ceiling of a cleanroom system, in particular for a cleanroom wall system, but it can also be used in industrial or office wall and ceiling systems. The panel is designed such that improved sealing is achieved along the edges of the surface section. The provided seal reliably seals the panel against a corresponding counterpart of the wall or ceiling system.
[0007]
[0007] The core concept of the invention lies in providing an undercut area on the collar(s) of the panel and in arranging a seal in this undercut area. The undercut area opposite the edge of the surface section is formed by a V-shaped design of the collar on its outer surface. This arrangement prevents the seal from accumulating or deforming when the panel is inserted or fitted against counterparts of the cleanroom system (such as, in particular, a frame structure like a truss or other panels), for example, by compression or wrinkling. At the same time, transverse forces that act on the seal during assembly or disassembly and could lead to displacement or detachment are significantly reduced. This facilitates assembly and ensures a permanently reliable seal, for example, against components of the truss or adjacent panels.
[0008]
[0008] As already indicated, the counterparts against which the panels according to the invention are arranged can be further panels or a frame structure of the cleanroom system. Suitable frame structures include, among others, stud walls or ceiling frames, which are typically constructed from beams running transversely to each other.
[0009]
[0009] For the purposes of the present invention, the term stud frame refers to a load-bearing frame structure, which in particular comprises vertical studs (posts) and horizontal crossbeams (rails) and serves to receive and fasten wall panels. The stud frame can, for example, be constructed of metal profiles and forms the supporting element of the wall system, in particular a cleanroom wall system, to which the wall panels are detachably or permanently attached and sealed against its components.
[0010]
[0010] Another advantage is that the seal can be applied during the manufacturing of the panel. This eliminates an additional assembly step and simplifies installation.
[0011]
[0011] The V-shape of the collar can also provide a locking or spring function that holds the panel in the installed state. In addition, the design can offer improved sound insulation as well as a certain degree of tolerance compensation during assembly.
[0012] Finally, the design allows for a continuous, seamless seal without interruption of the sealing plane in the area of adjacent collars, thus ensuring a particularly reliable seal against the respective counterpart. The term "seamless" here refers to a visually closed, and therefore virtually jointless, surface where the butt joints between adjacent panels, especially between the panel and the stud frame, are flush.
[0012]
[0013] The surface section can, in particular, have a rectangular shape, and its lateral edges can be perpendicular to each other. The surface section can be a side face of a cuboid wall section with a rectangular base. The surface section and / or the collar can be formed from sheet steel, aluminum, or stainless steel. The surface section can be formed entirely from sheet steel, aluminum, or stainless steel, but it can also include a transparent window area or a functional element such as a door or a flap.
[0013]
[0014] The V-shaped collar comprises an outer surface facing away from the surface section and an inner surface facing the surface section. Since the second collar section is angled outwards relative to the first collar section, the outer surface of the first collar section and the outer surface of the second collar section form an angle of less than 180 degrees and, in particular, greater than 90 degrees, thus an obtuse angle.
[0014]
[0015] Furthermore, according to the invention, the use of a panel according to the invention in a cleanroom system is disclosed. In addition, the panel according to the invention can also be used in an industrial room system or in an office room system, wherein the arrangement of the seal is then designed accordingly to seal the panel against a counterpart of the respective room system.
[0015]
[0016] The seal can be positioned on an outer surface of the first collar section facing away from the surface section and / or on an outer surface of the second collar section facing away from the surface section, for example, such that when the panel is inserted in a given installation direction, a contact pressure is exerted on the seal, for instance by stationary components of a frame structure. In this way, a particularly suitable arrangement of the seal can be provided, depending on the intended installation direction, to prevent unwanted displacement and detachment of the seal.
[0016]
[0017] The seal can be formed from a closed-cell polyethylene foam tape or a foamed polyurethane seal. A liquid-applied, then drying seal is also conceivable. The seal can be applied in a further process step. The seal can be arranged across the entire surface of the first collar section and / or the second collar section. The seal can be designed to be airtight, lightproof, and / or soundproof. The counterpart against which the seal seals the wall panel can be, in particular, a component of a frame construction or stud wall system, especially a cleanroom wall system, such as a vertical post or a horizontal beam, or another wall panel. The other wall panel can be designed as a counterpart in a particularly suitable way.For example, a wall panel designed as a counterpart can be designed at the adjacent edge to interact with the seal for a sealing effect, and can, for example, be smooth and without a collar along this edge.
[0018] The central surface section and the collar can be formed in one piece. For example, the surface section and the collar can be formed from a sheet of metal, in particular by stamping. The surface section and collar can be produced in a sheet metal bending process, in particular in a single, continuous process step.
[0017]
[0019] This allows for a reduction in the number of components within the wall panel. The number of potentially required sealing edges within the wall panel can also be reduced, permitting higher manufacturing tolerances. This results in particularly simple manufacturing of the wall panel.
[0018]
[0020] In one design, the seal extends along the edge over the entire length of the first collar section. This ensures a reliable seal along the entire length of the collar adjoining the surface section against a corresponding section of the wall system located there.
[0019]
[0021] In certain wall or ceiling systems, panels may be used where the surface sections only have a collar in corresponding sections of the lateral edges. Only by joining several such panels does a wall or ceiling with complete sealing result. In particular, the collar extends over the entire length of the edge.
[0020]
[0022] This ensures a reliable seal for the entire side of the panel where the collar is positioned along the edge of the central surface section. This offers greater flexibility in panel use, as the panel can essentially be used independently of other panels in a wall or ceiling system, while still ensuring adequate sealing along the edge and thus on the corresponding side of the panel.
[0021]
[0023] In another version, a further collar is arranged on another edge of the surface section. Such a panel thus enables sealing on another side of the surface section and ensures a reliable seal against a corresponding part of the wall or ceiling system located there.
[0022]
[0024] In this way, the individual geometry of a wall or ceiling system can be taken into account. The panel can provide a seal, for example, to several components of a cleanroom system, such as multiple posts or beams of a frame construction or a stud wall (post-and-beam construction).
[0023]
[0025] The edges can be perpendicular to each other. This is particularly the case with a rectangular area section.
[0024]
[0026] For example, the collars, especially where the edges are perpendicular to each other, can abut directly. The wall panel can have corresponding cutouts at the collars to allow the two collars to butt up directly against each other. In this way, sufficient sealing can also be provided in the corner area of the surface section where the collars abut each other.
[0025]
[0027] Additionally, the two collars can extend over the entire length of both edges. This allows for a suitable seal along the edges up to the corner areas of the surface section that are opposite the corner area of the adjacent collars.
[0028] In one version, a collar is arranged on each edge of the panel section. The collars can be provided with suitable cutouts to allow adjacent collars to butt directly against each other. This arrangement ensures a reliable seal along all edges of the panel section and thus on all sides of the panel against corresponding components of the room system. This allows for particularly flexible use of the panel in the design of a room system, so that a cleanroom wall or ceiling can be provided using just a single (sufficiently large) panel.
[0026]
[0029] Alternatively or additionally, a corner seal can be provided, which is arranged between the seals of two directly adjacent collars. This additional seal can also reduce the risk of one or more undesirable ventilation paths forming in the respective corner area of the wall or ceiling element where the two adjacent collars meet, for example due to forces acting during panel installation, and achieve a particularly reliable sealing effect.
[0027]
[0030] In one design, the seal is free of openings along the entire length of the collar and along one or more edges. This ensures a uniform sealing effect over the entire length of each edge.
[0028]
[0031] The second collar section can have an outer subsection and an inner subsection.
[0029]
[0032] The outer and inner sections can be directly adjacent to each other and, for example, essentially or at least partially overlapping. For instance, the collar in the second collar section can have a greater thickness than in the first. The outer and inner sections can each have the same thickness as the collar in the first collar section. The outer and inner sections can be arranged in the second collar section such that the collar in the second collar section has at least twice the thickness of the first collar section. For example, the second collar area is designed such that the collar is folded over at an edge opposite the surface section, with the lower section encompassing the folded-over part.
[0030]
[0033] The second collar section can form a spring, allowing the panel to be installed particularly easily into a wall or ceiling system without having to manipulate the seal. For example, the second collar section can have connecting elements that correspond to connecting elements of a conventional frame construction, such as appropriately arranged openings. The corresponding connecting elements of the second collar section and the frame construction can be designed to work together, if necessary using suitable fasteners such as screws or clips, to attach the wall panel to the framework. The spring action of the collar generates the sealing pressure for the gasket.
[0031]
[0034] Furthermore, according to the invention, a cleanroom system is provided, comprising at least one panel according to the invention and a frame structure, such as a stud frame, to which the panel is connected. The panel is inserted into the frame structure in a sealing manner. In particular, it is sealed against components of the frame structure. The cleanroom system can comprise several panels according to the invention, each of which is connected to the frame structure and sealed against its components.
[0032]
[0035] To connect the panel(s) to the frame structure, the collars of the panels can, for example, have suitable connecting elements as described above. Likewise, corresponding connecting elements, such as spring elements, clips, locking pins, clamping rails from suspended ceilings, or similar components, can be provided on the frame structure. The connecting elements of the panels and the frame structure can be designed to work together, if necessary using suitable fasteners, such as screws or clamps, to attach the panels to the frame structure.
[0033]
[0036] The above-described forms and configurations are merely examples and are not intended to limit the present invention in any way.
[0034]
[0037] Further advantages and embodiments of the invention will become apparent from the dependent claims, the description and the accompanying drawing.
[0035]
[0038] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.
[0036]
[0039] The invention is schematically illustrated with reference to exemplary embodiments in the drawing and is described in detail below with reference to the drawing. Figure 1 shows a highly schematic top view of a panel according to the invention in a frame construction.
[0037] Figure 2 shows two panels lying horizontally next to each other in a frame construction according to Figure 1 ,
[0038] Figure 3 shows two panels arranged vertically next to each other in a frame construction according to Figure 1 ,
[0039] Figure 4 shows an exemplary embodiment of a panel according to the invention in a partial perspective view ,
[0040] Figure 5 shows a schematic lateral sectional view of a panel according to the invention in a first embodiment ,
[0041] Figure 6 shows a schematic lateral sectional view of a panel according to the invention in accordance with a second embodiment.
[0042] Figure 7 shows the panel of Figure 5 in a schematic sectional view from the side in the state inserted into a frame construction according to the section line VI I-VI I of Figure 1 ,
[0043] Figure 8 shows the panel of Figure 6 in a schematic sectional view from the side, in the state inserted into a frame construction similar to the representation of Figure 7.
[0044]
[0040] Identical and similar features shown in the individual figures are designated by the same reference numerals.
[0045]
[0041] The invention is described below using the example of a cleanroom wall system using wall panels according to the invention. It is understood that the invention can also be used to the same extent for constructing ceiling systems. Therefore, no limitation should be seen in the following description. Furthermore, it should be emphasized that the described framework is a possible frame construction within the meaning of the present disclosure. The invention is particularly suitable for use in (suspended) ceiling systems with dry sealing.
[0046]
[0042] Figure 1 shows an embodiment of a cleanroom wall system 1 according to the invention, comprising a post-and-beam construction (so-called stud frame) 40 and a wall panel 10 with a central surface section 12 in a top view of the surface section 12. The wall panel 10 is attached to components of the stud frame 40 by means of suitable fasteners. As shown, the components comprise two vertical posts 41 and two horizontal beams 42. At the edges 14 of the surface section 12, the wall panel 10 has a collar 20 and is sealed there against the respective posts 41 or beams 42.
[0047]
[0043] Figures 2 and 3 show further embodiments of a cleanroom wall system 1 according to the invention, comprising two wall panels 10 inserted into a framework 40, in a top view of the parallel central surface sections 12 of the wall panels 10. The wall panels 10 are attached to the components of the framework 40, which comprise vertical posts 41 and horizontal rails 42, by means of suitable fasteners. The central surface sections 12 of the wall panels 10 extend, in particular, in one plane.
[0048]
[0044] In the example shown in Figure 2, the two wall panels 10 are arranged horizontally next to each other. Both wall panels 10 are jointly attached to a vertical post 41 arranged between the two wall panels 10, against which both wall panels 10 each provide a seal.
[0049]
[0045] In the embodiment shown in Figure 3, the two wall panels 10 are arranged vertically one above the other. Along one edge, the two wall panels 10 abut each other directly. Along this edge, the two wall panels 10 each provide a mutual seal. However, it is also conceivable that one of the two wall panels 10 is designed as a counterpart and is smooth and without a collar along this edge.
[0050]
[0046] In the following, an exemplary embodiment of a wall panel 10 according to the invention is described with reference to the illustrations in Figures 4, 5 and 6.
[0051]
[0047] Figure 4 shows a perspective view of a wall panel 10, as also shown in the examples in Figures 1 to 3. For clarity, only two of the collars 20 of the wall panel 10, arranged on the four edges 14 of the rectangular central surface section 12, are shown. Figure 5 shows a side sectional view of this embodiment along section line VV of Figure 4 with a seal 30 applied to the first collar section 22. Figure 6 shows a similar representation of an alternative embodiment with a seal 30 applied to the second collar section 24.
[0052]
[0048] The wall panel 10 for a cleanroom wall system 1 of Figure 4 comprises a central surface section 12 with a rectangular base, which is bounded by four edges 14. Adjacent edges 14 run perpendicularly and opposite edges 14 run parallel to each other. In the illustrated embodiment, a V-shaped collar 20 is arranged on each of the edges 14, extending over the entire length of the respective edge 14. The surface section 12 and the collar 20 can be formed in one piece from a sheet of steel and manufactured using a sheet bending process. To allow two adjacent collars 20 to abut directly, taking into account the shallow or obtuse V-shape, the collars 20 have corresponding notches at their lateral ends.
[0053]
[0049] Each of the collars 20 comprises a first collar section 22 and a second collar section 24. The two collar sections 22, 24 each correspond to one leg of a “V” describing the shape of the collar 20 in a side view.
[0054]
[0050] The first collar section 22 connects to the surface section 12 such that the surface section 12 and the first collar section 22 form an angle of less than 90 degrees, i.e., an acute angle, as can be seen particularly in Figures 5 and 6. A seal 30 for sealing the wall panel 10 against a counterpart 41, 42 of the cleanroom floor system 1 is arranged on an outer surface 23 of the first collar section 22 facing away from the surface section 12 (see Figures 4 and 5 as well as 7).
[0055]
[0051] The second collar section 24 is bent outwards relative to the first collar section 22. An outer surface 29 of the second collar section 24, facing away from the surface section 12, and the outer surface 23 of the first collar section 22 form an angle of less than 180 degrees and, in particular, greater than 90 degrees, i.e., an obtuse angle. This flat V-shaped design of the collar 20 creates an undercut area on its outer surface relative to the edge 14 of the surface section 12 to which the collar 20 abuts.
[0056]
[0052] The second collar section 24 has an outer subsection 26 and an inner subsection 28, which are arranged overlapping at least partially. The outer subsection 26 and the inner subsection 28 can each have the same thickness as the collar 20 in the first collar section 22, as shown. Accordingly, the collar 20 in the second collar section 24 has twice the thickness of the collar 20 in the first collar section 22.
[0057]
[0053] The second collar section 24 represents a spring with openings 34, which are designed to interact with (not shown) corresponding connecting elements of vertical posts 41 or horizontal bars 42 of a stud frame for fastening the wall panel 10 to the stud frame 40 (such as suitably designed clips or locking pins or rivets or screws for a secure connection).
[0058]
[0054] The seal 30 is arranged flat on the outer surface 23 of the first collar section 22, and thus in the undercut area, and extends along the edge 14 over the entire length of the first collar section 22. The seal 30 is free of any openings over the entire extent of the collar 20 along the edge 14.
[0059]
[0055] Between the seals 30 of two immediately adjacent collars 20, a corner seal 32 is arranged in each case, as can be seen in Figure 4. Accordingly, the wall panel 10 has a continuous, uninterrupted, planar seal 30 extending along all edges 14 of the central surface section 12, which is further reinforced in the corners of the surface section 12 by the corner seals 32. In the illustrated wall panel 10, the sealing plane is thus uninterrupted, and unwanted ventilation paths can be reliably avoided.
[0060]
[0056] Figure 7 shows the wall panel 10 of Figure 5, which is attached to a stud / post 41 of a stud frame. The stud 41 has a spring element 46, for example in the form of a spring clip, which, as shown, can be attached to the stud 41 by means of a rivet 48. The second collar section 24 of the wall panel 10 is inserted into this spring element 46 in the direction of arrow P, which indicates the mounting direction of the wall panel. The central surface section 12 of the wall panel is flush with a surface 45 of the stud 41.
[0061]
[0057] The spring element 46 is formed on both sides, so that the stand 41 can be used in both directions. This also makes it possible to insert another wall panel from the opposite side - at the bottom in the illustration of Figure 7.
[0062]
[0058] By inserting the wall panel 10 in the direction of arrow P, the seal 30, which is arranged in the undercut area of the collar as described, comes to lie between the collar (here the first collar section 22) and the stud frame, thus ensuring a reliable seal of the wall panel against the stud frame. During insertion, the seal is "protected" in the flat V-shaped area of the undercut, so that, according to the invention, compression or twisting of the seal during installation due to acting transverse forces during insertion is avoided.
[0059] In the embodiment shown in Figures 6 and 8, the seal 30 is not arranged on the outer surface 23 of the first collar section 22 as in Figure 5, but rather flat on the outer surface 29 of the second collar section 24. Accordingly, in this case too, the seal 30 is arranged in the undercut area.
[0063]
[0060] This embodiment is particularly suitable in situations where the wall panel cannot be inserted from the "front" (as shown in Figure 7), for example, if this area in front of the framework is inaccessible for mounting wall panels (this can be the case if building elements such as load-bearing wall sections or posts, or even already installed machinery, are located in this area). In such cases, the wall panel can be inserted from the "back" in the opposite direction according to the direction of arrow P in Figure 8; due to the opposite sliding direction, the seal 30 is then arranged on the other flank of the V-shape on the second collar section 24 in order to avoid being subjected to potentially twisting transverse forces.
[0064] Reference symbol list
[0065] 1 Cleanroom system, cleanroom wall system
[0066] 10 panels, wall panel
[0067] 12 central area section
[0068] 14 edges
[0069] 20 collars
[0070] 22 first collar section
[0071] 23 Outer surface of the first collar section
[0072] 24 second collar section
[0073] 26 outer section of the second collar section
[0074] 28 inner subsection of the second collar section
[0075] 29 Outer surface of the second collar section
[0076] 30 Seal
[0077] 32 Corner seal
[0078] 34 breakthroughs
[0079] Frame construction, post-and-beam construction, stud wall 40
[0080] 41 vertical posts, stands
[0081] 42 horizontal bars, crossbeams
[0082] 45 surface post
[0083] 46 Spring element
[0084] 48 rivets
[0085] P Arrow Insertion direction
Claims
Patent claims 1. Panel (10) for a room system (1), in particular a cleanroom system (1), wherein the panel (10) comprises a central surface section (12) bounded by a plurality of edges (14), wherein a V-shaped collar (20) is arranged on at least one of the edges (14), the collar having a first collar section (22) and a second collar section (24), wherein the first collar section (22) adjoins the surface section (12) such that the surface section (12) and the first collar section (22) form an angle of less than 90 degrees, wherein the second collar section (24) is bent outwards relative to the first collar section (22), and wherein a seal (30) for sealing the panel (10) against a counterpart (10, 41, 42) of the system is provided on an outer surface (23, 29) of the collar (20) facing away from the surface section (12). cleanroom system (1) is arranged.
2. Panel (10) according to claim 1, wherein the second collar section (24) is angled outwards at an angle of less than 180 degrees relative to the first collar section (22), in particular to form an undercut area on the collar (20).
3. Panel (10) according to claim 1 or 2, wherein the first collar section (22) and the second collar section (24) form an obtuse angle.
4. Panel (10) according to one of the preceding claims, wherein the seal (30) is arranged on an outer surface (23) of the first collar section (22) facing away from the surface section (12) and / or on an outer surface (29) of the second collar section (24) facing away from the surface section (12).
5. Panel (10) according to one of the preceding claims, wherein the central surface section (12) and the collar (20) are formed in one piece.
6. Panel (10) according to one of the preceding sprays, wherein the seal (30) extends along the edge (14) over the entire length of the first collar section (22).
7. Panel (10) according to one of the preceding claims, wherein the collar (20) extends over the entire length of the edge (14).
8. Panel (10) according to one of the preceding claims, wherein a further collar (20) is arranged on a further edge (14) of the surface section (12).
9. Panel (10) according to claim 6, wherein the two edges (14) are perpendicular to each other.
10. Panel (10) according to one of claims 1 to 9, wherein a collar (20) is arranged on each of the edges (14) of the surface section (12).
11. Panel (10) according to one of claims 8 or 9, wherein collars (20) extending perpendicular to each other are directly adjacent to each other.
12. Panel (10) according to claim 11, with at least one corner seal (32) arranged between the seals (30) of two directly adjacent collars (20).
13. Panel (10) according to one of claims 8 to 12, wherein the two collars (20) extend over the entire length of both edges (14).
14. Panel (10) according to one of the preceding claims, wherein the seal (30) is formed without penetration over the entire extent of the collar (20) along one or more edges (14).
15. Panel (10) according to one of the preceding claims, wherein the second collar section (24) has an outer subsection (26) and an inner subsection (28).
16. Cleanroom system, in particular cleanroom wall system (1) , comprising at least one panel (10) according to one of the preceding claims, which is fitted in a sealing manner against components (10, 41, 42) of the cleanroom system.
17. Cleanroom system (1) according to claim 16, wherein the panel (10) is sealed against further panels (10) and / or against components (41, 42) of a frame structure (40).
18. Cleanroom system (1) according to claim 16 or 17, wherein at least one post (41) and / or bar (42) of the frame construction (40) has at least one spring element (46) for clamping the second collar section (24) of the panel (10) in the installed state.