CN108756102A - A kind of wall color-changing device - Google Patents

Abstract

A wall discoloration device, comprising a box body, the inner wall of the box body is provided with chute respectively on the front and back sides, each chute is divided into two arc-shaped grooves and two horizontal grooves parallel to each other, the upper and lower parts on the back of the inner wall of the box body Horizontal grooves are respectively set up, and arc-shaped grooves are respectively set on both sides of the back of the inner wall of the box body. Two sprockets are respectively fixedly installed, and the sprockets are respectively collinear with the center lines of the corresponding arc grooves. The present invention is suitable for writing rooms. The box body is fixedly installed on the top of the wall and does not occupy people's work space. The strip-shaped through-groove faces downward and is close to the wall. The replacement of the wallpaper can be realized through the above operations. The wallpaper is passed through the thin iron sheet and The magnetic strips are laid flat on the wall, enabling the wallpaper to be reused and convenient when changing the wallpaper so that it is detached from the wall.

Description

A wall color changing device

technical field

The invention belongs to the technical field of interior decoration, in particular to a wall color changing device.

Background technique

The decoration of indoor walls usually selects paint and wallpaper, and selects different colors or patterns according to the needs of users. As people pay more attention to health and environmental protection, more and more people choose wallpaper to decorate walls. However, the existing wallpaper is glued to the wall through glue, which is not easy to replace, and it is easy to cause aesthetic fatigue, so the wall color-changing device emerges in time, but the existing wall color-changing device will take up more space in the room and compress people's use. Space affects people's indoor work and living experience.

Contents of the invention

The invention provides a wall color changing device to solve the defects in the prior art.

The present invention is achieved through the following technical solutions:

A wall color-changing device, comprising a box body, the front and rear sides of the inner wall of the box body are provided with chute respectively, each chute is divided into two arc-shaped grooves and two parallel horizontal grooves, the upper and lower parts Horizontal grooves are respectively set up, and arc-shaped grooves are respectively set on both sides of the back of the inner wall of the box body. Two sprockets are fixedly installed respectively, and the sprockets are respectively collinear with the center line of the corresponding arc groove. The two sprockets on the rear side are connected by a chain plate, and the two sprockets on the front side are connected by a The chain plate connection of the two sprockets on one side is respectively provided with cylindrical grooves on the back, and the front of the cylindrical grooves are respectively provided with through holes. The through holes are respectively collinear with the center line of the corresponding cylindrical grooves. Each through hole Respectively communicate with the corresponding cylindrical groove and the inside of the box at the same time. The back side of the inner wall of the box is fixedly connected to the rear end of the electric push rod. The front end of the electric push rod is fixedly installed with a forward and reverse motor. Front, the front end of the output shaft of the reversing motor is fixedly connected to the rear end of the rotating shaft, and the rotating shaft can pass through the corresponding through holes in turn. The front and rear sides of the rotating shaft are respectively fixed with pressure plates, and the pressure plates are respectively collinear with the center line of the rotating shaft. The pressing plates can be located in the corresponding cylindrical grooves at the same time, the outer circumference of the pressing plates can be in contact with the inner walls of the corresponding cylindrical grooves respectively, and the first gears are fixedly installed on the front and rear sides of the rotating shaft respectively, and the first gears are aligned with the center line of the rotating shaft. Collinear, the first gear is located between the two sprockets, there are several wallpaper rollers parallel to each other in the box, the center line of the wallpaper rollers is perpendicular to the back of the inner wall of the box, and the outer peripheral sides of the wallpaper rollers are respectively fixedly connected One end of the wallpaper and the other end of the wallpaper are respectively wound clockwise around the corresponding wallpaper roller for several weeks. The front and rear sides of each wallpaper roller are respectively fixedly connected to one end of the fixed shaft, and the outer circumference of the fixed shaft is respectively fixed with the second gear. The second gear can Mesh with the corresponding first gear at the same time respectively, several sliders are respectively arranged in the chute, one end of the slider is respectively located outside the corresponding chute, and the outer circumference of the slider is respectively in contact with the inner wall of the corresponding chute, the slider can Slide along the corresponding chute respectively, the sliders correspond to the fixed shafts one by one, the other ends of the fixed shafts are respectively connected to the corresponding sliders through bearings, grooves are respectively set on one side of the sliders, and the bottom surface of the upper groove is uniform It communicates with the inside of the box, and the top surface of the groove located below is connected with the inside of the box. The outer circumference of the chain plate is fixedly connected to one end of several levers, and the other ends of the levers can be snapped into the corresponding grooves at the same time. Inside, a strip-shaped through-groove is set on one side of the bottom surface of the box, and the strip-shaped through-groove and the rotating shaft are located on the same side of the box, the other end of the wallpaper can pass through the strip-shaped through-groove, and the bottom side of the inner wall of the box is fixed and installed The inductor is located on the inner side of the strip-shaped through groove, and the inductor is respectively connected with the electric push rod and the forward and reverse motor circuit at the same time.

According to the above-mentioned wall color-changing device, solid strips are fixedly installed on the other ends of the wallpaper.

A wall discoloration device as described above, several installation blocks are fixedly installed on the top periphery of the box body, the installation blocks are evenly distributed on the outer periphery of the box body, the top surfaces of the installation blocks are respectively provided with installation holes, and the bottom surfaces of the installation holes are uniform. Communicate with the outside world.

In the above-mentioned wall color-changing device, wedge-shaped strips are respectively provided on both sides of the top surface of the strip-shaped through groove, and the bottom surfaces of the wedge-shaped strips are respectively fixedly connected with the bottom surface of the inner wall of the box body.

According to the above-mentioned wall color-changing device, four installation blocks are fixedly installed on the outer periphery of the top of the box body, and the installation blocks are respectively located at the top four corners of the box body.

According to the above-mentioned wall color changing device, the box body is made of transparent material.

The advantage of the present invention is that: in the initial state of the present invention, the pressure plates are respectively located in the corresponding cylindrical grooves, the opening of the grooves is opposite to the rotation direction of the chain plate, the forward and reverse motors are started, and the forward and reverse motors drive the rotating shafts to rotate. There is a large friction force between the pressure plate and the cylindrical groove, which can drive the corresponding sprocket to rotate, and then can drive the chain plate to rotate. With the rotation of the chain plate, the driving rod can be respectively snapped into the corresponding groove at the same time , so that the slider can be driven to slide along the chute. The slider is connected with the wallpaper roller through the fixed shaft, so that the wallpaper roller can move synchronously with the corresponding slider. When one of the wallpaper rollers moves to the inside of the strip-shaped through groove, the sensor The wallpaper roller is sensed, the sensor is equipped with a control module, and the sensor transmits the detected signal to the control module, and the control module controls the electric push rod to shrink, and the electric push rod can drive the forward and reverse motor and the rotating shaft to move backward at the same time, Until the pressure plate breaks away from the cylindrical groove, the rotating shaft can no longer drive the sprocket to rotate. The distance between the second gears on the front and rear sides of each wallpaper roller is equal to the distance between the two first gears. As the rotating shaft moves backward, The first gear can mesh with the corresponding second gear at the same time, so as to drive the corresponding wallpaper roller to rotate, and the wallpaper roller rotates to relax the wallpaper, and the wallpaper can pass through the strip-shaped through groove, and several thin iron sheets are fixedly installed on the inner side of the wallpaper , fixedly install several magnetic strips on the wall, the thin iron sheet can be absorbed by the magnetic strip, so that the wallpaper is attached to the wall, when the wallpaper needs to be replaced, first separate the thin iron sheet from the magnetic strip, and then control the forward and reverse motor Turn and fold the wallpaper. After the wallpaper is folded, the forward and reverse motor stops working, and then the electric push rod is controlled to extend, and the pressure plate is located in the cylindrical groove again. The mutual cooperation between them can drive several wallpaper rollers to move at the same time until another wallpaper roller moves to the inner side of the strip-shaped through groove, and repeat the above operation to realize the replacement of wallpaper. The present invention is suitable for writing rooms. The box body is fixedly installed on the top of the wall and does not occupy people's work space. The strip-shaped through groove faces downward and is close to the wall. The replacement of the wallpaper can be realized through the above operations. The wallpaper is passed through the thin iron sheet and The magnetic strip is tiled on the wall, enabling the wallpaper to be reused, and it is also very convenient to replace the wallpaper to separate it from the wall. Cooperate with each other, so that the structure of the present invention is relatively simplified, only one set of power device is needed to realize the replacement of the wallpaper roller and the retraction of the wallpaper, which can reduce the volume of the present invention, making the present invention easy to install, and because there are many There is a suspended ceiling, and the cabinet is set above the suspended ceiling. It is only necessary to reserve a space for the wallpaper to pass through on the side of the suspended ceiling close to the wall, which greatly improves the aesthetics. The psychological response that matches the work can improve work concentration, thereby improving work efficiency.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is a schematic structural view of the present invention; Fig. 2 is an enlarged view of the A-direction view of Fig. 1; Fig. 3 is an enlarged view of the B-direction view of Fig. 2 .

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

A wall color-changing device, as shown in the figure, includes a box body 1, and the front and rear sides of the inner wall of the box body 1 are respectively provided with chute 2, and each chute 2 is divided into two arc-shaped slots 211 and two parallel horizontal slots 212, the upper and lower parts of the inner wall back of the box body 1 are respectively provided with horizontal grooves 212, and the inner wall back sides of the box body 1 are respectively provided with arc grooves 211, the concave surfaces of the two arc grooves 211 are opposite, and the two arc grooves 211 The ends communicate with the corresponding horizontal grooves 212 at the same time. Two sprockets 3 are fixedly installed on the front and rear sides of the inner wall of the box body 1. The sprockets 3 are collinear with the centerlines of the corresponding arc grooves 211 respectively. The two sprockets 3 are connected by a chain plate 4, and the two sprockets 3 on the front side are connected by the same chain plate 4, and the backs of the two sprockets 3 on one side are provided with cylindrical grooves 6 respectively. The front of the shaped groove 6 is provided with a through hole 7 respectively, and the through hole 7 is collinear with the center line of the corresponding cylindrical groove 6 respectively, and each through hole 7 communicates with the corresponding cylindrical groove 6 and the inside of the box body 1 respectively, and the box The back side of the inner wall of the body 1 is fixedly connected to the rear end of the electric push rod 8, and the front end of the electric push rod 8 is fixedly installed with a forward and reverse motor 9, the output shaft of the forward and reverse motor 9 faces forward, and the output shaft of the forward and reverse motor 9 The front end is fixedly connected to the rear end of the rotating shaft 10, and the rotating shaft 10 can pass through the corresponding through holes 7 in turn. The front and rear sides of the rotating shaft 10 are respectively fixed with pressing plates 11, and the pressing plates 11 are respectively co-linear with the center line of the rotating shaft 10. The pressing plate 11 Can be located in the corresponding cylindrical groove 6 respectively at the same time, the outer circumference of the pressure plate 11 can contact and cooperate with the inner wall of the corresponding cylindrical groove 6 respectively, and the front and rear sides of the rotating shaft 10 are respectively fixedly installed with the first gear 12, the first gear 12 Collinear with the center line of the rotating shaft 10, the first gear 12 is located between the two sprockets 3, and several wallpaper rollers 14 parallel to each other are arranged in the box body 1, and the center lines of the wallpaper rollers 14 are all perpendicular to the center line of the box body 1. On the back of the inner wall, one side of the outer circumference of the wallpaper roller 14 is fixedly connected to one end of the wallpaper, and the other end of the wallpaper is wound clockwise around the corresponding wallpaper roller 14 for several weeks, and the front and rear sides of each wallpaper roller 14 are respectively fixedly connected to one end of the fixed shaft 15 , the outer circumference of the fixed shaft 15 is fixedly installed with the second gear 16 respectively, the second gear 16 can mesh with the corresponding first gear 12 at the same time, respectively, several sliders 17 are arranged in the chute 2, and one end of the slider 17 is respectively located at the corresponding Outside the chute 2, the outer circumference of the slider 17 is respectively in contact with the inner wall of the corresponding chute 2, the slider 17 can slide along the corresponding chute 2 respectively, the slider 17 corresponds to the fixed shaft 15 one by one, and the fixed shaft 15 The other end of each is connected to the corresponding slider 17 through a bearing respectively, and grooves 18 are provided on one side of the slider 17 respectively. The surfaces are all communicated with the inside of the box body 1, and the outer circumference of the chain plate 4 is fixedly connected to one end of several driving rods 19, and the other ends of the driving rods 19 can be snapped into corresponding grooves 18 respectively at the same time. There is a strip-shaped through-groove 20 on the side, and the strip-shaped through-groove 20 and the rotating shaft 10 are located on the same side of the box body 1, and the other end of the wallpaper It can pass through the strip-shaped through-groove 20, and an inductor is fixedly installed on one side of the bottom surface of the inner wall of the box body 1. The inductor is located on the inner side of the strip-shaped through-groove 20. circuit connection. In the initial state of the present invention, the pressure plates 11 are respectively located in the corresponding cylindrical grooves 6, the opening of the groove 18 is opposite to the rotation direction of the chain plate 4, the forward and reverse motor 9 is started, and the forward and reverse motor 9 drives the rotating shaft 10 to rotate. Due to the relatively large frictional force between the pressing plate 11 and the cylindrical groove 6, the corresponding sprocket 3 can be driven to rotate, and then the chain plate 4 can be driven to rotate. into the corresponding groove 18, so as to drive the slider 17 to slide along the chute 2, the slider 17 is connected with the wallpaper roller 14 through the fixed shaft 15, so that the wallpaper roller 14 can move synchronously with the corresponding slider 17 respectively, when When one of the wallpaper rollers 14 moves to the inner side of the strip-shaped through groove 20, the sensor senses the wallpaper roller 14, and a control module is arranged in the sensor, and the sensor transmits the detected signal to the control module, and the control module controls the electric push rod 8 Shrink, the electric push rod 8 can drive the forward and reverse motor 9 and the rotating shaft 10 to move backward at the same time, until the pressure plate 11 breaks away from the cylindrical groove 6, the rotating shaft 10 can no longer drive the sprocket 3 to rotate, and each wallpaper roller 14 front and rear sides The distance between the second gears 16 is equal to the distance between the two first gears 12. As the rotating shaft 10 moves backward, the first gears 12 can mesh with the corresponding second gears 16 at the same time, thereby driving the corresponding The wallpaper roller 14 rotates, and the wallpaper roller 14 rotates to loosen the wallpaper. The wallpaper can pass through the strip-shaped through groove 20. Several thin iron sheets are fixedly installed on the inside of the wallpaper, and several magnetic strips are fixedly installed on the wall. The thin iron sheets can be The magnetic strip is adsorbed, so that the wallpaper is attached to the wall. When the wallpaper needs to be replaced, the thin iron sheet is separated from the magnetic strip first, and then the forward and reverse motor 9 is controlled to reversely fold the wallpaper. After the wallpaper is folded, the forward and reverse motor 9 stops working , and then control the extension of the electric push rod 8, and the pressure plate 11 is relocated in the cylindrical groove 6. At this time, the forward and reverse motor 9 is controlled to rotate forward, and through the mutual cooperation between the sprocket 3, the chain plate 4 and the driving rod 19, the Drive several wallpaper rollers 14 to move until another wallpaper roller 14 moves to the inner side of the strip-shaped through-groove 20, and repeat the above operations to realize the replacement of the wallpaper. The present invention is suitable for writing rooms. The box body 1 is fixedly installed on the top of the wall so as not to occupy people's work space. The strip-shaped through groove 20 faces downward and is close to the wall. The replacement of the wallpaper can be realized through the above operations. The wallpaper is passed through the thin iron The tiles and magnetic strips are tiled on the wall, so that the wallpaper can be reused, and it is also very convenient to replace the wallpaper so that it can be separated from the wall. The mutual cooperation with the cylindrical groove 6 makes the structure of the present invention relatively simplified, and only one set of power device is needed to realize the replacement of the wallpaper roller 14 and the retraction of the wallpaper, which can reduce the volume of the present invention and make the present invention It is easy to install, and because there are many suspended ceilings in the office, the cabinet 1 is set above the suspended ceiling, and it is only necessary to reserve a space on the side of the suspended ceiling close to the wall for the wallpaper to pass through, which greatly improves the aesthetics. According to the nature of the work of the day Choose wallpapers of appropriate colors to enable people to have a psychological reaction that matches the work, improve work concentration, and then improve work efficiency.

Specifically, as shown in the figure, the other ends of the wallpaper described in this embodiment are respectively fixed with solid strips 21 . When the wallpaper roller 14 wraps the wallpaper, the solid strip 21 can make the wallpaper be in a vertical state, and the wallpaper can be gathered more tightly, which can reduce the space occupied by the wallpaper roller 14, thereby reducing the volume of the box body 1 and relaxing the wallpaper roller 14. When wallpapering, the wallpaper in the vertical state can be closer to the wall, which is convenient for the user to control the extension of the wallpaper, and the user can stick the wallpaper on the wall more conveniently.

Specifically, as shown in the figure, several installation blocks 22 are fixedly installed on the outer periphery of the top of the box body 1 described in this embodiment, and the installation blocks 22 are evenly distributed on the outer periphery of the box body 1, and the top surfaces of the installation blocks 22 are respectively provided with installation holes. 13. The bottom surfaces of the mounting holes 13 are all communicated with the outside world. Bolts can be passed through the mounting holes 13, and reserved screw holes are provided on the top surface of the wall, and the casing 1 can be fixed on the top surface of the wall by bolts, which is very convenient for disassembly and assembly.

Further, as shown in the figure, wedge-shaped strips 5 are respectively provided on both sides of the top surface of the strip-shaped through groove 20 in this embodiment, and the bottom surfaces of the wedge-shaped strips 5 are respectively fixedly connected with the bottom surface of the inner wall of the box body 1 . The wedge-shaped surfaces of the wedge-shaped strips 5 are obliquely towards the inside of the box body 1 respectively, and the other end of the wallpaper can slide downward along the wedge-shaped surfaces of the wedge-shaped strips 5, thereby facilitating the passage of the wallpaper from the strip-shaped through groove 20.

Furthermore, as shown in the figure, four installation blocks 22 are fixedly installed on the outer periphery of the top of the box body 1 described in this embodiment, and the installation blocks 22 are respectively located at four corners of the top of the box body 1 . The installation of at least four installation blocks 22 in cooperation with the top surface of the wall can ensure that the box body 1 is sufficiently stable and easy to assemble and disassemble.

Furthermore, as shown in the figure, the box body 1 described in this embodiment is made of transparent material. The user can see the distribution of wallpapers of different colors through the cabinet 1, so that the user can choose a suitable wallpaper color.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (6)

1. A wall color-changing device, characterized in that: it includes a box (1), and the front and rear sides of the inner wall of the box (1) are respectively provided with chute (2), and each chute (2) is divided into two arc-shaped slots (211) and two parallel horizontal grooves (212), the upper and lower parts of the back of the inner wall of the box (1) are respectively provided with horizontal grooves (212), and the two sides of the inner wall of the box (1) are respectively provided with arc grooves (211), the concave surfaces of the two arc-shaped grooves (211) are opposite, and the two ends of the arc-shaped grooves (211) communicate with the corresponding horizontal grooves (212) at the same time, and the front and rear sides of the inner wall of the box body (1) are respectively fixed Install two sprockets (3), the sprockets (3) are respectively collinear with the centerlines of the corresponding arc grooves (211), and the two sprockets (3) on the rear side are connected by a chain plate (4) , the two sprockets (3) on the front side are connected by the same chain plate (4), and the backs of the two sprockets (3) on one side are respectively provided with cylindrical grooves (6), and the cylindrical grooves ( 6) are respectively provided with through holes (7) in front of them, and the through holes (7) are respectively collinear with the centerlines of the corresponding cylindrical grooves (6). ), the box body (1) is internally connected, the back side of the inner wall of the box body (1) is fixedly connected to the rear end of the electric push rod (8), and the front end of the electric push rod (8) is fixedly installed with a forward and reverse motor (9), The output shaft of the reversing motor (9) faces forward, and the front end of the output shaft of the reversing motor (9) is fixedly connected to the rear end of the rotating shaft (10), and the rotating shaft (10) can pass through the corresponding through hole (7) in sequence However, the front and rear sides of the rotating shaft (10) are respectively fixed with pressing plates (11), and the pressing plates (11) are respectively collinear with the center line of the rotating shaft (10), and the pressing plates (11) can be respectively located in the corresponding cylindrical grooves (6 ), the outer circumference of the pressure plate (11) can contact and cooperate with the inner wall of the corresponding cylindrical groove (6) at the same time, and the first gear (12) and the first gear (12) are respectively fixedly installed on the front and rear sides of the rotating shaft (10). They are all collinear with the center line of the rotating shaft (10), the first gears (12) are located between the two sprockets (3), and several mutually parallel wallpaper rollers (14) are arranged in the box body (1). The center line of (14) is perpendicular to the back of the inner wall of the box (1), and the outer peripheral sides of the wallpaper roller (14) are respectively fixedly connected to one end of the wallpaper, and the other end of the wallpaper is wound clockwise around the corresponding wallpaper roller (14). For several weeks, the front and rear sides of each wallpaper roller (14) are respectively fixedly connected to one end of the fixed shaft (15), and the outer circumference of the fixed shaft (15) is respectively fixedly equipped with a second gear (16), and the second gear (16) can respectively and simultaneously Engage with the corresponding first gear (12), and several sliders (17) are respectively arranged in the chute (2), and one end of the slider (17) is respectively located outside the corresponding chute (2), and the slider (17) The outer circumferences of the sliders are in contact with the inner walls of the corresponding chute (2), and the sliders (17) can slide along the corresponding chute (2). The sliders (17) correspond to the fixed shafts (15) one by one, and the fixed shafts The other end of (15) passes through the bearing and the corresponding slider (1 7) Connection, grooves (18) are provided on one side of the slider (17), the bottom surface of the upper groove (18) communicates with the inside of the box (1), and the top of the lower groove (18) Both surfaces are connected with the inside of the box body (1), and the outer circumference of the chain plate (4) is fixedly connected to one end of several driving rods (19), and the other ends of the driving rods (19) can be snapped into corresponding grooves at the same time ( 18), a strip-shaped through-groove (20) is provided on one side of the bottom surface of the box body (1), and the strip-shaped through-groove (20) and the rotating shaft (10) are located on the same side of the box body (1), and the other end of the wallpaper can be The strip-shaped through-groove (20) passes through, and the bottom surface of the inner wall of the box body (1) is fixed with an inductor. The inductor is located on the inner side of the strip-shaped through-groove (20). , Forward and reverse motor (9) circuit connection. 2. A wall color-changing device according to claim 1, characterized in that: the other ends of the wallpaper are respectively fixed with solid strips (21). 3. A wall color-changing device according to claim 1, characterized in that: several installation blocks (22) are fixedly installed on the outer periphery of the top of the box body (1), and the installation blocks (22) are evenly distributed in the box body The outer periphery of (1) and the top surface of the mounting block (22) are respectively provided with mounting holes (13), and the bottom surfaces of the mounting holes (13) are all communicated with the outside world. 4. A wall discoloration device according to claim 1, characterized in that: wedge-shaped strips (5) are respectively provided on both sides of the top surface of the strip-shaped through groove (20), and the bottom surface of the wedge-shaped strip (5) They are respectively fixedly connected with the bottom surface of the inner wall of the box body (1). 5. A wall color-changing device according to claim 3, characterized in that four installation blocks (22) are fixedly installed on the outer periphery of the top of the box body (1), and the installation blocks (22) are respectively located in the box body ( 1) The top four corners. 6. A wall color-changing device according to claim 1, characterized in that: the box (1) is made of transparent material.