Patent Document

FIELD OF THE INVENTION 
     The invention relates generally to the structure and operation of a spring barrel module, which is installed in a small space. 
     BACKGROUND OF THE INVENTION 
     The size of portable electronic equipment in particular is being constantly reduced. This makes great demands, e.g. on the usability and durability of the various mechanical components in the equipment. 
     The physical components of electronic equipment are constructed to be as simple as possible, suitable for mass production and easy to install on automated assembly lines. The components of equipment should be designed so that tolerance variations occurring in the components do not obstruct the installation or lessen the performance of the equipment. 
     Examples of small electronic equipment containing mechanically movable components are mobile terminals, CD stations, and CD players. The smallest mobile terminals are physically so tiny, that when the loudspeaker is held to the ear, the microphone does not reach all the way to the user&#39;s mouth without special arrangements. Mobile terminals of this kind can be enlarged with the aid of a telescope structure or with some other enlargement implementation, such as a collapsible structure. The force needed for the enlargement can be supplied by the user, or obtained from a spring or a motor, for example. 
     A mobile terminal that includes a body part and a grip part is described in the applicant&#39;s earlier patent application FI20001008, which has not been published by the filing date of the present application. 
     A relatively large portion of the body part is located within the sleeve-like grip part. The grip part is mounted for longitudinal slideable movement between a retractable position and an extended position. A spring barrel, within which a spring and a bidirectional damper are combined, is installed in the body part of the mobile terminal. When the mobile terminal is in the idle position, the body part is within the sleeve-like part, and the spring is compressed, that is, the spring is in its stressed state. When the fastening lock of the grip part and the body part is released, the stored force of the spring pushes out the body part of the mobile terminal from the grip part into the extended or operative position. The damper slows down the mechanical movement of the body part in relation to the grip part. More specifically, the mechanical movement of the body part is controlled by the bi-directional damper, which absorbs a part of the spring force to prevent the body part from jumping out suddenly and noisily into the enlarged position. After the mobile terminal has been used, the spring is reset, by the body part being pushed down manually into the grip part. 
     Typically there is very little space in small equipment. Valuable space is saved by a solution whereby both the spring and the damper are installed within the same housing. 
     However, it is a drawback in the described solution that the damper does not function in the normal manner at low or freezing temperatures (below 0° C.). This is mainly due to the behaviour of the damping oil in the damper housing. The oil solidifies and thus causes a high torque and stress to the mechanical components of the spring barrel. This results in a serious malfunction: the opening mechanism of the mobile terminal works very slowly if at all. 
     In addition, when the damper does not work or works very slowly, there is always the risk that the user will try to open or close the equipment by force. In the worst case such behaviour may break the mechanical components of the spring barrel. 
     SUMMARY OF THE INVENTION 
     The invention especially concerns a spring barrel module which is installed in a small space in small-sized equipment, such as a mobile terminal, and which is easy to install and economically advantageous to manufacture. It is an objective of the present invention to implement the structure of the spring barrel module so that the energy stored in the spring of the spring barrel module is adapted to convert into a linear or rotary movement, so that a certain small piece of equipment, e.g. a mobile terminal, which is designed to open, will open in a controlled manner and smoothly. It is especially important that the opening force remains as uniform as possible during the entire movement. 
     It is also an object of the present invention to make the manual closing operation easy and smooth for the user and in addition to protect the mechanism when the user uses force to either open or close the equipment. 
     This objective is achieved in the manner described in the independent claim. Advantageous embodiments of the invention are defined in the dependent claims. 
     The spring barrel module includes a combined spring and a damper. This solution takes less space than a separate spring and damper. The spring is preferably a clock spring. The energy stored in the spring is converted by a rotary spring shaft and then by a belt or some other such means into a linear or rotary motion. In an advantageous embodiment the damper is unidirectional, i.e. it works in one direction only. This unidirectional damper is implemented by a clutch means which connects the damper plate to the spring shaft causing slowed down rotation when the tightened spring is released. Correspondingly, the clutch loosens the connection between the damper plate and the spring shaft when the spring is tightened in order to make the manual closure easier. 
     Should the ambient temperature drop below a certain temperature level depending on the damping fluid used e.g. below −10° C. degrees, the damper will not dampen the rotation at all. 
     When the electronic equipment is closed, the spring in the spring barrel module is in its tightened state. When the spring is released, the spring force is converted by a spring shaft which is adapted to rotate by some means such as a belt into a linear or rotary motion, so that that component of the electronic equipment which is adapted to move will open in a controlled and smooth manner. When the component adapted to move is closed, e.g. by pushing it manually, the spring will reset. 
     Depending on the application, more than one spring barrel module can be installed in one piece of equipment. The place where the spring barrel is installed depends on how large a space there is in the equipment for installation of the spring barrel module. Another decisive factor is how long or wide a movement is desired for the component adapted to move. 
     The unidirectional feature of the damper improves both usability and durability. In addition, breakage of the mechanical components of the spring barrel is prevented by an overload clutch, which means that the spring barrel module will tolerate even relatively rough handling of the equipment. 
     An advantageous way of passing on the force obtained from the spring is by adapting the spring to rotate the spring shaft and to pass on the force by way of a toothed rack and gear to that component of the electronic equipment which is adapted to be movable. 
     Another advantageous way of passing on the force obtained from the spring is by adapting the spring to rotate the spring shaft and to pass on the force by way of a threaded screw to that component of the electronic equipment which is adapted to be movable. 
     Yet another advantageous way of passing on the force obtained from the spring is by adapting the spring to rotate the spring shaft and to pass on the force through a wheel adapted to be rotary to that component of the electronic equipment which is adapted to be movable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, the invention will be described in greater detail in connection with advantageous embodiments and with reference to the examples shown in FIGS. 1-6 in the appended drawings, wherein: 
     FIG. 1 a  is an exploded view of such components of a spring barrel module which are essential to the invention; 
     FIG. 1 b  shows the spring barrel module of FIG. 1 a  in its assembled state; 
     FIGS. 2 a - 2   h  illustrate some implementations and functions of the spring and damper shaft of the spring barrel module; 
     FIGS. 3 a - 3   b  illustrate how the force obtained from the spring barrel module is passed on through a wire/belt; 
     FIGS. 4 a - 4   b  illustrate how the force obtained from the spring barrel module is passed on through a toothed gear and a toothed rack; 
     FIG. 5 illustrates how the force obtained from the spring barrel module is passed on through a threaded screw; and 
     FIGS. 6 a - 6   b  are examples of limited rotation of the spring shaft. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following, a small spring barrel module according to the invention will be described by way of example by referring to FIGS. 1-6. 
     The invention will be described first by referring to FIGS. 1 a - 2   h . In addition, FIGS. 3 a - 6   b  show some examples of how the force obtained from the spring can be passed on. It should be noted that the relative dimensions of the components shown in the figures may vary in reality. 
     With the aid of an exploded view, FIG. 1 a  illustrates the basic structure of a spring barrel module provided with a unidirectional damper. The spring barrel module includes a spring chamber cap plate  100 , a spring  101 , a barrel frame  102 , a seal ring  103 , a spring shaft  104 , a damper shaft  105 , a damper plate  106 , a damper leaf spring  107 , a damper chamber cap plate  108 , and an auxiliary spring  113 . 
     FIG. 1 b  illustrates the same spring barrel module in its assembled state. 
     From FIGS. 1 a  and  1   b  illustrate how the spring barrel module is assembled. 
     The spring shaft  104  is a solid piece with a circular cross-section, however, so that the cross-section of the first end of the shaft is many-sided, preferably the part fitting into the cap plate  100  hole. The cross-sectional dimension of the spring shaft varies when the shaft is viewed in the longitudinal direction from the first end  117  to the other end  118 , but so that the spring shaft is symmetrical in relation to the central axis extending in the longitudinal direction. The relative axial lengths of the shaft components of different cross-sectional sizes depend on the application used. 
     The barrel frame  102  is shaped uniformly as a cylindrical piece without a cap and bottom. Essentially mid-way in the cylindrical piece there is a partition  114  with a circular cross-section, the diameter of which is equal to the cylinder diameter. The partition is located at right angles to the cylinder walls to form two separate open chambers: a first chamber and a second chamber. 
     The first end  117  of the spring shaft can be pushed at right angles through an essentially round hole  115  in the middle of the partition dividing the barrel frame into chambers. The hole diameter is so large that the spring shaft goes into the hole, but at the same time so small that a shoulder  112  located essentially in the central part of the spring shaft does not fit into the hole. Thus, this shoulder functions as a stop preventing the spring shaft from being pushed deeper. The spring shaft is thus partly on the spring chamber side and partly on the damper chamber side. A seal ring, e.g. an O-ring  103 , is installed around the spring shaft in such a way that it is compressed in between the said shoulder and the partition dividing the barrel frame into chambers. 
     The inner end of clock spring  101  is connected mechanically to that part of the spring shaft (to the point  128  in FIG. 1 a ) which is located in the spring chamber. The outer end of the clock spring is attached to the inner wall (to the point  129  in FIG. 1 b ) in the spring chamber of the barrel frame. As is known, a clock spring is a spirally wound strip-like spring steel wire. 
     The damper shaft  105  is a solid piece symmetrical in relation to the central axis in the longitudinal direction of the shaft, the first end  116  of which is of a circular cross-section and the second end  119  of which is of an essentially many-sided shape, preferably square. The relative lengths of the first end and second end of the shaft in the longitudinal direction of the shaft depend on the application used. In the longitudinal direction there is a hole  121  with a circular cross-section, extending through the damper shaft. The hole is located essentially in the middle of the shaft and extends from one end to the other of the shaft. The hole diameter is a bit larger than the diameter of the second end of the spring shaft, so that the second end of the spring shaft can be pushed easily through the hole in the damper shaft. The second end of the spring shaft, which is to be pushed through the hole, is of a length slightly longer than the total length of the damper shaft. 
     In the cross-sectional surface of the spring shaft there is a unidirectional circular gear (as seen from the direction of the second end  118 ). Correspondingly, in the cross-sectional surface of the first end  116  of the damper shaft there is a further unidirectional circular gear. The circular gear surfaces of the shafts are machined in such a way that the gears fit exactly and tightly against each other, so that when the spring shaft is rotated in a clockwise direction (in this example), the toothed gear of the spring shaft will in normal use rotate with the toothed gear of the damper shaft in one rotational direction. 
     The damper plate  106  is of a circular cross-section and has a diameter that is smaller than the diameter of the frame barrel. The second end  119  of the damper shaft can be pushed at right angles through a hole  120  essentially of a rectangular shape and located essentially in the middle of the damper plate. The hole  120  in the damper plate is approximately of the same size as the diameter of the second end of the damper shaft, however, so that the damper shaft can be easily moved back and forth at right angles to the damper plate. 
     On the damper plate side opposite to the damper shaft there is a damper leaf spring  107  arranged to press the circular gears together. The second end of the spring shaft functioning as a coaxial pin extends through the hole in the damper shaft and then further extends through an essentially round hole located in the middle of the damper leaf spring. 
     The spring chamber cap plate  100  and the damper chamber cap plate  108  are plate-like uniform pieces of an essentially circular cross-section. They may be straight or bent into a shape, depending on the application. The cap plate of the damper chamber is a solid piece, but essentially in the middle of the spring chamber cap plate there is a circular hole  122 , the diameter of which is such that the first square end of the spring shaft can be pushed at right angles through the hole. 
     When the spring chamber cap plate  100 , the barrel frame  102 , and the damper chamber cap plate  108  are attached to each other, they will together form a closed cylindrical barrel in which there are two chambers. A clock spring is located in the first chamber  109 , and a damper is located in the second chamber  110  (see FIG. 1 b ). The length of the clock spring depends on the application, the thickness of the spring, and the size of the spring barrel module. The second chamber is filled with some known damper viscous liquid. The choice of damper liquid does not restrict the invention. The O-ring  103  prevents leakage of liquid from the central hole  115  in the barrel frame. There is no liquid in the first chamber. 
     The components mentioned in the foregoing may be manufactured from different metals or alloys. However, the choice of material for the components does not restrict the invention. The most important thing is that the components, which are adapted to move mechanically, are made of a sufficiently durable material. 
     In the following, the operation of the spring barrel module will be described in greater detail with reference to FIGS. 2 a - 2   g . It is assumed in the following that the spring barrel module is installed in a mobile terminal of the kind described above, that is, in such a mobile terminal where the body part moves in relation to the grip part. However, these examples are not concerned with the question of how the force obtained from the spring  101  is passed on such as through the linear motion of the body part of the mobile terminal in relation to the grip part, because this is not essential from the viewpoint of the present invention. 
     FIG. 2 a  is an exploded view of a spring and a damper shaft and of a damper plate and a leaf spring. The spring shaft  104  is preferably a uniform piece of metal, which is shaped as shown in the figure. It may be manufactured by machining or by casting in a mould. Of course, the shaft may also be made of some other durable material. At the thickest part of the spring shaft  104 , opposite the before-mentioned shoulder  112 , a unidirectional circular gear  112  is arranged. 
     FIG. 2 f  illustrates the gear as seen from above. The heavier line shows the ridges of the tooth, while the thinner line shows the valleys in the tooth. In the figure, the coaxial pin  118 , in the foregoing called the second end of the spring shaft  104 , is located in the middle at right angles to the paper plane. A narrow groove  119  with a smooth bottom is formed between the coaxial pin and the damper shaft. 
     In FIG. 2 a  the corresponding unidirectional circular gear  125  is arranged in the cross-sectional surface of the damper shaft  105 . In the middle of damper plate  106 , there is a square hole  120 , into which the square part of the damper shaft fits. In the middle of the damper shaft, there is a circular hole  121  smaller than the one mentioned above, through which the coaxial pin  118  of the spring shaft can be pushed. In the middle of the damper leaf spring there is a hole  123  for the coaxial pin of the spring shaft. 
     The damper shaft is adapted to move in the vertical direction in the figure in relation to the spring shaft  104  and the damper plate  106 . 
     FIG. 2 b  illustrates the function of the spring shaft and the damper when the body part of the mobile terminal emerges into the operating position from the grip part. At first, the body part of the mobile terminal is within the sleeve-like grip part. A clock spring (not shown in the figure) is hereby tightened, that is, it is wound tightly around the spring shaft. When the locking latch between the body part and the grip part is released, the spring begins to unwind. The unwinding spring rotates the spring shaft  104  in a clockwise direction, whereby the toothed gear of the spring shaft rotates the toothed gear of the damper. The toothed gears are pushed tightly against each other by the force obtained from the leaf spring  107 . FIG. 2 c  shows more exactly the relative positions of the toothed gears. When the toothed gear of the spring shaft rotates the toothed gear of the damper, the damper plate  106  rotates, too. Simultaneously, the body part of the mobile terminal emerges from the grip part into its operating position. The movement of the body part is smooth and controlled, because damping liquid in the damper chamber  110  softens the rotation with the help of the damper plate. 
     FIG. 2 d  illustrates the operation of the spring shaft and the damper when the body part of the mobile terminal is pushed into the grip part to its idle position. At first, the mobile terminal is in the operating position, i.e. the body part has emerged from the grip part. In this position the clock spring is not entirely stressed, but is partly unwound from around the spring shaft in the spring chamber  109  (the clock spring is not shown in FIG.  2 ). When the body part of the mobile terminal is pushed manually into the grip part, the spring shaft  104  rotates anti-clockwise, whereby the clock spring is wound more tightly around the spring shaft. Due to the unidirectional circular gear, the toothed gear of the spring shaft and the toothed gear of the damper shaft are being pushed away from each other, whereby the damper shaft compresses the leaf spring  107 , i.e. the leaf spring is stressed. The toothed gear of the damper shaft will slow down or stop the rotation completely. This means that the force needed for closing the mobile phone to a retracted position is smaller than the force needed for opening it to an extended position. FIG. 2 e  illustrates the positions of the toothed gears in relation to each other. 
     Unidirectional damping and overload protection can be performed by selecting suitable slopes for the toothed gears. As has been stated, in normal use the dampening acts in one direction only. The allowed load is defined as relatively small. When the load increases so as to exceed a predetermined amount, the overload clutch will act. FIG. 2 h  illustrates the teeth in more detail. An arrow  126  shows the direction of the rotation when the mobile terminal is opened in the operating position by force. The damper shaft resists rotation. An arrow  127  shows the direction of the rotation when the body part of the mobile terminal is pushed into the grip part. 
     When overload protection is used, the slope of the front edge of a tooth must be &gt;90°, i.e. the more gentle the angle of the slope the easier is the overload action and vice versa. 
     A super elastic material may be chosen as the leaf spring material which has a sufficiently low transition temperature, e.g. −10° C. Below the transition temperature, the structural phase of the super elastic material changes and the spring loses its spring characteristics. Thus, the toothed gears of the damper shaft and spring shaft are in the position shown in FIG.  2   e . When the temperature rises to the point of transition, the spring characteristics are restored. 
     FIG. 2 g  shows an exploded view of an advantageous alternative manner of implementation. The situation is otherwise similar to the one shown in FIG. 2 a , but in this embodiment an auxiliary leaf spring  113  is mounted on the spring shaft side of the damper plate  106 , and there is a hole  124  for the spring shaft in the middle of the leaf spring. This leaf spring is smaller and considerably weaker than the damper leaf spring. For example, its material is ordinary spring steel, which will not lose its spring characteristics at low temperatures. When leaf spring  107  loses its spring characteristics below the transition temperature, the auxiliary leaf spring  113  pushes the damper shaft into the position shown in FIG. 2 d  and disengages the teeth from each other. In reality, the weaker leaf spring is smaller than shown in the figure and easily fits into the groove  119  around the spring shaft (see FIG. 2 f ). The purpose of the arrangement shown in FIG. 2 g  is to make sure that no dampening takes place at predetermined low temperatures. 
     However, if there is no super-elastic leaf spring in use, but a normal steel leaf spring, the damper and the overload feature will still work and will protect the mechanism when the terminal is opened by the force. If a clutch is not fitted at all, the damper will still work, but only bi-directionally. Unidirectional damping means that less force is needed to close the terminal than to open it. In this way the use of the terminal is comfortable and smooth. The overload clutch acts if the user gets irritated with the slow opening of the terminal and gives a sudden pull at the body part. 
     The auxiliary spring  113  can be installed in two different ways: either in such a way that the auxiliary spring serves to open the clutch means, which connects the damper plate to the spring shaft, or in such a way that the auxiliary spring serves to close the said clutch means. 
     In the former alternative, depicted as spring  113   b  in FIG. 1 b , instantaneous initial friction is eliminated and in the latter alternative there always exists a certain minimum friction for the damper. This is depicted with the auxiliary spring moved to the position of  113   a  in FIG.  2 . With the help of such arrangements, the spring barrel withstands even relatively rough use. In other words, if the user tries to open or close the equipment by force, the mechanical components of the spring barrel fail to break. 
     The following is an examination with reference to FIGS. 3-6 of different examples of how the force obtained from the spring of the spring barrel module can be passed on to that part of the equipment which is adapted to move. It is assumed that the equipment is a mobile terminal of the kind described above. 
     FIG. 3 a  illustrates a solution, whereby one belt or wire is used. The figure shows the spring barrel module as seen in the longitudinal direction of the spring shaft. The cylindrical spring barrel  300  is fixed. The first end of the wire/belt  302  is attached in some suitable way to that part of the spring shaft  301  which extends outside the spring barrel, in the figure to point  303 . The second outer end of the wire/belt is attached to the mobile terminal. From the viewpoint of this application, it is not essential how or at which point the second end of the wire/belt is attached to the mobile terminal. The wire/belt length is L. 
     When the body part of the mobile terminal is located within the grip part, the clock spring is in its tightened state and the wire/belt  302  is wound at least partly around the shaft. When the locking of the body part and grip part is opened, the stored spring force of the clock spring rotates the spring shaft in the manner described earlier, whereby the wire/belt wound around the shaft will unwind at least partly from around the shaft. 
     FIG. 3 b  illustrates a solution using two belts or wires. The first end of the belts/wires is attached to points  303  and  304  according to the figure, while the second outer end is attached in such a way to the equipment in use so that their points of attachment in the equipment are located in different directions at right angles to the spring shaft. 
     Otherwise, the situation is similar to that shown in FIG. 3 a . In the figure, the length of one wire/belt is L, whereby the equipment opens up in its entirety for a distance 2L. The force required for opening is F/2 for one direction. This solution is especially suitable when a linear or rotary motion is needed in two different directions. 
     Two separate wires/belts may be attached to the spring shaft on the same plane or on different planes, or placed beside each other in relation to the longitudinal direction of the shaft. 
     An embodiment of this kind may be used in any kind of equipment where two opening/closing movements in different directions are required. 
     FIG. 4 a  shows an embodiment, whereby the force obtained from the spring is passed on through a toothed rack  402  and a toothed gear  401  to that part of the electronic equipment which is adapted to be movable. The cylindrical spring barrel  400  is fixed. The gear is at that end of the spring shaft which emerges from the spring chamber. It is assumed, that the toothed rack is attached to the grip part of the mobile terminal while the spring barrel module is attached to the body part. When the spring shaft rotates, the gear rotates along the toothed rack, whereby the body part emerges from the grip part. When the body part is pushed manually into the grip part, the gear rotates in the opposite direction, thus rotating the spring shaft, whereby the clock spring winds around the spring shaft and is thus reset. 
     FIG. 4 b  illustrates an embodiment with a principle similar to the one shown in FIG. 3 b . Instead of a belt/wire, a toothed gear  403  and two separate toothed racks  404  are used. The cylindrical spring barrel  400  is fixed. The shaft  403  rotates. 
     FIG. 5 shows an embodiment, whereby the force obtained from the spring is passed on through a threaded screw  501  to that part of the electronic equipment which is adapted to be movable. 
     In this embodiment, the first end  503  of the spring shaft, which extends past the cylindrical spring shaft barrel  500 , is of a length which is a multiple of the axial length of the spring shaft barrel. In addition, the said shaft part is machined in such a way that there are threads on at least a portion of its outer surface. In this solution a ring element  502  is attached to that part of the equipment which is adapted to be movable, whereby the outer shape of ring element  502  is made suitable for the application. A hole extends axially through the ring element from one end to the other, with a mating thread for a threaded screw. When the spring shaft rotates, e.g. clockwise, due to the thread the ring element moves along the shaft and away from the spring barrel module, whereby that part of the equipment which is adapted to be movable will open. When that part of the equipment which is adapted to be movable is closed, e.g. when it is pushed manually, the ring element moves towards the spring barrel module, the spring shaft rotates anti-clockwise, and the spring of the spring barrel module is wound around the spring shaft and reset. 
     FIG. 6 a  illustrates a situation, where the rotation of the spring shaft  601  is limited. In other words, the spring shaft rotates at a predetermined angle α (α&lt;360°), for example. The cylindrical spring barrel is fixed. 
     FIG. 6 b  shows another alternative solution where the rotary motion is limited. The spring barrel  604  is fixed. The force is transferred from the spring shaft  603  through a wheel  602  in the manner shown by the figure. In other words, the wheel  602  transmits rotation of the shaft  603  to a belt/wire (not shown in FIG. 6 b ), the first end of which is attached to the wheel and the second end is attached to that part of the equipment which is adapted to be movable. Of course, the solution shown in the figure may also be implemented in such a way that there is a toothed gear rack instead of a wheel, whereby there must also be a toothed gear on the shaft end. 
     It should be noted that the examples presented in the foregoing represent only some of the various possibilities for implementation. Persons skilled in the art will find it obvious that various other combinations can be made based on the examples presented above. 
     The size of the spring barrel is decisive, as is the space reserved for the spring barrel module in the equipment. For industrial production, it is important that the assembly and installation of the spring barrel are as simple and economically advantageous as possible. 
     Although the invention is designed to be especially suitable for small-size equipment, the invention is not limited to applications for such equipment. Naturally, the spring barrel module described may be built into equipment of any size. The structure and function of the spring barrel module are decisive. 
     The manner of the attachment most suitable in each case is affected, for example, by the materials chosen, by the place where the spring barrel module is installed, and by how great is the stress applied to the point of attachment. The wire/belt may be attached in many different ways: by riveting, by welding, by gluing, etc. 
     Of course, the spring shaft and the damper shaft can also be assembled from different parts. 
     It should be noted that there are many different application possibilities. Depending on each application, the spring barrel is installed in the equipment at the most suitable point. This means in practice that even in different variations of similar equipment the spring barrel may be located in different places for either technical or aesthetic reasons. In addition how many spring barrel modules are installed in the equipment depends on the application. 
     Although different ways of implementation have been described in the foregoing with reference to a mobile terminal, the spring barrel module may be installed in equipment of any kind requiring smooth linear or rotary motion. There are very many different applications: a disk tray of a CD/DVD stations and a computer keyboard emerging from under the tabletop are mentioned as examples.

Technology Category: 0