Abstract:
Tilting, retractable screen device for tables, which comprises means for guiding the screen between a substantially vertical concealed position in which the screen is located under the surface of the table and a use position in which the screen projects from said surface, in which the guide means are configured in order to guide the table in a movement that takes the screen from the concealed position to a use position, which is tilted with respect to the surface of the table, said movement being composed of a vertical translation until the screen projects substantially from the surface, followed by a rotation that takes the screen to the use position, such that same may be used when tilted but remains vertical when stowed.

Description:
[0001]    The present invention relates to a retractable tilted screen device for desks, which optimizes space utilization while being convenient to use for users. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are some known retractable screen devices for desks comprising means for guiding the screen between a vertical concealed position wherein the screen is housed below the surface of the table and a working position wherein the screen protrudes beyond said surface, which are designed to adapt the use of working desks and to protect the screens. 
         [0003]    Typically, these devices comprise a housing which houses the screen and the sliding mechanism of the screen between the two positions and is arranged under the desk. 
         [0004]    This housing has the disadvantage of occupying a space under the table which may be uncomfortable for the user whose leg-space is reduced. 
         [0005]    Another solution is to dispense with the tilt of the screen when being used, but the disadvantage is that the user&#39;s line of vision is not perpendicular to the plane of the screen and eye contact with others is reduced, with the discomfort this entails. 
         [0006]    A solution to the viewing angle problem is to rotate the entire screen-mechanism-housing assembly around an axle situated approximately at the level of the opening, as proposed in European patent application EP 1574150, however, it does not solve the leg-space problem under the desk. 
         [0007]    On the other hand, these devices generally comprise a lid to close the opening, designed to keep the housing closed when the screen is hidden, especially to provide a desk without inconvenient holes in the surface when the screens are not being used and to avoid dust or any object entering when the screen is not in use. 
         [0008]    A common solution is a lid hinged to the desk that opens driven by the screen itself when it emerges. However, this solution has several disadvantages:
       The contact forces between the lid and the screen, namely the screen frame, can cause scratches on the frame and also friction noises that may be annoying.   The lid is visible when the screen is in working position, which is unsightly because it involves a visible part of a mechanism on the desk, and highlights the utilitarian nature of the screen, unwanted features when optimization of the visual atmosphere is sought.       
 
         [0011]    Therefore, a retractable screen device that solves the problems described is needed, namely, that both in extreme positions and in positions taken when in movement, the screen should take up as little space as possible under the table to avoid invading the leg-space, while providing the desired inclination of the screen when in working position. On the other hand, the present invention also aims to provide a retractable screen device that has a lid which does not brush against the screen when it opens and is hidden when in working position. 
       DESCRIPTION OF THE INVENTION 
       [0012]    To that end, this invention provides a retractable screen device for desks, comprising means for guiding the screen between a substantially vertical concealed position whereby the screen is situated below the desk surface and a working position whereby the screen protrudes beyond the surface, and is characterized in that the guide means are configured to guide the desk in a movement that takes the screen from the concealed position to a working position which is inclined in relation to the desk surface, said movement being formed by a vertical translation until the screen protrudes noticeably beyond the surface followed by a rotation that takes the screen to the working position. 
         [0013]    This sequence of movements solves the technical problems, since it tilts the screen into its working position and on the other hand, allows the screen and its housing to be stored in a vertical position. 
         [0014]    Preferably, the inclination corresponding to the working position is of about 20 degrees, optimum angle when the screen is arranged with its underside substantially at the level of the desk surface. 
         [0015]    Advantageously, the guide means comprise two horizontal axles joined to the screen, being located one below the other, a pair of upper axle guides that guide it according to a substantially vertical movement and at least another pair of lower axle guides that guide it according to a movement with vertical and horizontal components in the final upward stretch, so the upward movement of the screen causes it to tilt. 
         [0016]    This configuration allows a twist at the end of the upward movement of the screen (or equivalently, at the beginning of the downward movement) and a translational movement during the rest of the trajectory. 
         [0017]    More preferably, the pair of lower axle guides comprise a section near the surface of the desk which is tilted as regards to a lower section, which is substantially vertical, so that the screen tilts back, pivoting on the upper axle in a rotational movement, when the ends of the lower axle slide along the section of such guides which is near the surface. 
         [0018]    More advantageously, the screen can pivot with respect to a support according to such upper axle, so that this support transmits the efforts between the various parts, including the drive motor, and enables the easy removal of the screen for maintenance or replacement 
         [0019]    More advantageously, the lower axle guides comprise a last section substantially aligned with the lower section, so that the displacement at the end of the trajectory is substantially translational. 
         [0020]    Therefore, once the screen is tilted, it can still go an extra length without changing its inclination. This allows in particular simplifying the upward drive control, since no great accuracy is needed to deactivate the vertical displacement drive motor. Indeed, when reaching the working position, the screen takes speed and therefore has some kinetic energy. If the guide were to end at that point, either a motor control would be needed allowing reversing its rotational direction in a short time, or there would be an impact between the axle ends and the guide end. Therefore, the extension of the guide allows the screen to lose some kinetic energy by the action of gravity and also allows a less precise control system, that is, at a lower cost than that needed to stop the screen in a shorter trajectory. 
         [0021]    More preferably, the device comprises a screen protection housing attached to the underside of the desk. 
         [0022]    Additionally, the said support comprises four wheels that roll along such guides of the upper axle, so that these wheels and the support form a link between these guides and the upper axle guiding it according to a vertical movement. Cooperation between the four wheels and the upper axle guides ensure a smooth run of the upper axle in its vertical translational motion, and avoid ill linking conditioning. 
         [0023]    On the other hand, the device of the present invention comprises a lid closing said opening and means for moving the lid between a closed position and a retracted position whereby said lid is situated below the desk surface. 
         [0024]    This feature solves some of the disadvantages of prior art, since the lid is only visible when closed and if an object is accidentally placed on top, the lid will not put pressure on the object as it will withdraw into position without protruding beyond the plane of the desk, it being the mechanism for lifting the screen, much more robust, which will put pressure on the object. 
         [0025]    Preferably, in this closed position the lid is substantially flush with the plane of the desk surface so that the desk has the whole of its working surface available when the screen is not in use, and furthermore has no parts in relief which could be unsightly. 
         [0026]    Advantageously the means for moving the lid comprise a hinge axle between the lid and the desk, this axle being located close to one edge of the opening and below the level thereof, an articulated rod with an appendix joined to the lid so that movement of the rod induces a rotation of the lid, and linking means between the movement of the screen and the movement of the rod, so that the lid retracts shortly after the beginning of the ascent of the screen and closes just before the end of the descent of the screen. 
         [0027]    This is accomplished by a simple mechanism in which there are no contact forces between the screen frame and lid, thus avoiding scratches, and allowing fine materials to be used for the screen frame, such as wood, etc. 
         [0028]    More preferably, the linking means between the screen movement and the movement of the rod comprise a mounted slide along the rod and which rotates on an axle joined to the screen and provided with means to perform a drag force on the rod for an upward or downward stretch of the screen. 
         [0029]    More advantageously, the means for performing a drag force on the rod comprise a widening of the rod and a sliding mounted element on the slide driven by a spring toward the rod, the spring constants being determined so that when the element is at the level of the widening, the normal force exerted by the element on the rod causes an upward or downward frictional drag force, and when it is above the widening, it does not make contact with the rod. 
         [0030]    This system allows the slide, dragged by the screen itself, to activate the rod movement just enough to make the lid open and close. 
         [0031]    More advantageously, the device comprises means to stabilize the lid position in the closed position and in the retracted position. Such means, which can be performed with a stable spring mechanism in the two positions, a set of magnets, or an imbalance between the lid and rod weights, guarantees the stability of the lid in each of the two resting positions, in the first two cases, or only the opening position in the third. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    For a better understanding of what has been stated some drawings which, schematically and solely by way of example, show a practical embodiment. 
           [0033]    FIGS.  1 . a  to  1 . e  are elevational views which represent the relative position of the screen and the desk at different times of the upward or downward movements. 
           [0034]    FIGS.  2 . a  to  2 . d  are elevational views of the device of the invention which shows the relative arrangement of its main components when the screen goes through the different positions. 
           [0035]      FIG. 3  depicts a rear elevational view of the lid mechanism of the device of the invention. 
           [0036]      FIG. 4  is a schematic elevational view of the lid mechanism of the device of the invention when the screen is in a concealed position. 
           [0037]      FIG. 5  is a schematic elevational view of the lid device of the invention when the screen is in a working position. 
           [0038]      FIG. 6  is a schematic section of part of the rod and slide in a situation where there is pressure and hence friction and in another where there is no contact. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0039]    As shown by FIGS.  1 . a  to  1 . e  and  2 . a  to  2 . d , the invention relates to a retractable screen  2  device  1  for desks  3 , provided with means for guiding the screen between a significantly vertical concealed position A where the screen  2  is below the desk surface  3 , preferably housed in a protective housing  13 , and a working position B in which the screen  2  protrudes above the surface of the desk and is characterized in that the guide means are configured to guide the desk in a movement that takes the screen from a concealed position A to a working position B which is tilted as regards to the surface of the desk  3 , preferably with an α angle of about 20 degrees, while said movement is formed by a vertical translation  4  until the screen  2  protrudes noticeably above the surface followed by a rotation  5 , which takes the screen to the working position, thus enabling a comfortable viewing of the screen and maximum leg-space, as the pivoting with respect to the desk occurs with respect to an axle located on the underside of the screen, whereby it hardly takes up any space in front of the screen. 
         [0040]    According to a preferred embodiment of the invention, as shown in FIGS.  2 . a  to  3 , the movement means of the screen include two horizontal axles  6  and  7  joined to the screen  2 , one  6  being situated below the other  7 , a pair of guides  8  of the upper axle  7  that guide it according to a substantially vertical movement and at least another pair of guides  9  of the lower axle  6  that guide it according to a movement with vertical and horizontal components, so that the upward movement of the screen  2  causes it to tilt. 
         [0041]    The movement with the vertical and horizontal components is accomplished in the present embodiment through the lower axle guides  9 , which consist of a section  10  near the surface of the desk  3  tilted with respect to a lower section  11 , which is substantially vertical so that the screen  2  is tilted backwards, rotationally  5  pivoting on the upper axle  7 , when the ends  18  of the lower axle  6  slide down said section  10  of said guides  9  near the surface. 
         [0042]    The translational movement of the upper axle  7  is accomplished by mounting the latter on a support  15  having only one degree of free movement which is vertical. Therefore, the screen and support are articulated through the upper axle  7 . 
         [0043]    To guide the upper axle  7  in vertical translation, the support  15  comprises four wheels  16  that roll along such guides  8  of the upper axle  7  so that these wheels and support are a link between the guides  8  and the upper axle that guide it according to a vertical movement. By providing 2 wheels on each guide  8 , this prevents the rotation of the screen according to an axle perpendicular to the screen itself and therefore any rigidity between the support  15  and said guides  8   
         [0044]    Another advantageous feature of this preferred embodiment is that the guides  9  have a last section  12  substantially aligned with the lower section  11 , so that the displacement  13  is substantially translational at the end of the trajectory. Indeed, once the lower axle  6  has passed the inclined section, it begins to slide along this last stretch  12  which is parallel to section  11  along which the axle  6  continues to slide, so that the screen has a final movement that does not change the tilt. Therefore, the screen need not be immobilized when it has reached its tilted position, as it has a section without needing an accurate control, which would be expensive, ensuring the smooth operation of the device. 
         [0045]    Also, the device of the invention comprises a control system, already known in itself, which includes an adapter card that controls the entries and exits to control the position of the screen using a microcontroller. These entries can be connected to position photocells and, preferably, the speed control in the upward movement involves a slow beginning, then changing to the normal speed, and when the lower axle enters the tilted section it goes back to a slow speed. The downward movement is equivalent but in reverse. The slow movements avoid sudden changes in the speed of the screen support assembly, particularly at the ends of the guides, where there is a greater risk of impact and therefore stress that may damage the device. Also, to avoid overexertion, the device of the invention may comprise an automatic shutdown system depending on the resistance detected in the upward or downward movements 
         [0046]    The device can be controlled by means of two buttons, one for going up and one for going down, mounted on the side of the opening, preferably on the right-hand side, and likewise each of them can be the stop button while the other has been pressed. Another alternative is to control it with a remote control or automation, such as AMX, Creston, or any other adapted to the device. 
         [0047]    On the other hand, as shown in  FIGS. 4 and 5 , the device  1  of the preferred embodiment is provided with a lid  20  to close the opening  19  of said desk  3  and means for moving between a closed position A and a retracted position C that allows the passage of the screen  2 , and specifically in the device of the invention, the retracted position is located below the surface of the desk  3 , as shown in  FIG. 5 . Therefore, to take it from the closed position A, in which, as shown in  FIG. 4  the lid  20  is flush with the plane of the surface of the desk  3 , to the retracted position C, it does not need at any time to protrude beyond the plane of the desk  3 , whereby the movements of the lid  20  are not impeded by objects that can be found inadvertently on the desk  3 . 
         [0048]    According to the preferred embodiment of the invention, as shown in  FIGS. 4 and 5 , to move the lid  20  between the two positions A and C, the device  1  comprises a hinge axle  21  between the lid  20  and the desk  3  located close to an edge of the opening  19  and below the level thereof, a rod  22  articulated with an appendix  23  joined to the lid  5 . 
         [0049]    Specifically, these elements are arranged so that the movement  24  of the rod  22  induces a rotation  25  of the lid  20 , and linking means between the movement  4  of the screen  2  and the movement  24  of the rod  22 , so that the lid  20  withdraws soon after the screen  2  starts to rise and closes shortly before the end of the descent of the screen  2 . This mechanism is very simple and reliable and prevents contact between the lid  20  and the screen  2 . 
         [0050]    In this preferred embodiment, the linking means between the movement  4  of the screen  2  and the movement  24  of the rod  8  comprise a mounted slide  26  along the rod  22  and rotating on an axle  27  joined to the screen  2  and provided with means for dragging the rod  22  during an upward  32  or downward  31  trajectory of the screen  2 . 
         [0051]    Axle  27  joined to the screen, means that the movement of one implies that of the other according to a rigid body kinematics, but does not necessarily imply a direct binding of the joint axle  27  to the screen  2 , yet rather preferably, both screen  2  and axle are fixed to a sturdy support responsible for driving the screen. 
         [0052]    Thus, by activating the screen  2  elevation, the slide  26 , whose axle of rotation  27  is joined to the screen  2 , pushes the rod  22  upwards, and the latter will trigger the rotation of the lid  20 . 
         [0053]    The displacement of the lid  20  between its two extreme positions is achieved with a minimum displacement of rod  22  end, determined mainly by the length of said appendix  23 . 
         [0054]    Therefore, it is only necessary for the slide  26  to activate the axle  22  during a stretch of the upward or downward trajectory. This is achieved with the rod  22  dragging means that are built into the slide  26 . 
         [0055]    As illustrated in  FIG. 6 , according to the preferred embodiment described, the means for performing a drag force on the rod  22  include a widening  28  of the rod  22  and a mounted sliding element  29  on the slide  26  driven by a spring  30  toward the rod  22 , the spring  30  constants being determined such that when the element is at the height of the widening  28 , the normal force exerted by the element  29  on the rod  22  causes an upward  32  or downward  31  frictional drag force, and when it is above the widening  28 , it does not come into contact with the rod  22 . 
         [0056]      FIG. 6 , for the sake of simplicity, shows a widening  28  whose section is offset with respect to the rod section  22  immediately above. 
         [0057]    This simple mechanism means that, in the extreme positions of the lid  20 , i.e. the end of the appendix, the movement of the end of the rod  22  is prevented, and the friction force between the rod  22  and the element  29  and the larger section stretch, either upward  31  or downward  32 , is strong enough to move the rod  22  in the opposite direction to that where it is blocked. 
         [0058]      FIG. 6  shows the relative positions that may exist between the rod  22  and the slide  26 . Specifically, when the slide  26  is in the lower position shown, whether going up or down, it drags the rod  22  upwards or downwards respectively, then opening or closing the lid  20  of the opening  19 . When in the upper position, it is noted that the resting length of the spring  30  is determined such that the element  29  fails to make contact with the rod  22 . Obviously, the widening  28  is very short, since a minimum run is needed to produce a rotation of the lid  20 . 
         [0059]    On the other hand, since the lid-appendix assembly revolves around an axle  21 , the rise of the end of the appendix  23  which is attached to the rod  22  also involves a sideways movement, which induces the rod  22 , apart from the upward movement  24 , to rotate 33. Hence the need to provide the slide  26  with a degree of freedom of rotation with respect to the screen  2 . This degree of freedom is provided by the rotation axle  27  between the slide  22  and the screen  2 . 
         [0060]    In addition to providing stability in the extreme positions, the device of the invention comprises means to stabilize the position of the lid  20  in the closed position A and in the retracted position C, for example by a spring mechanism stable in both positions or a set of magnets, one in the lid  20  and another fixed to the desk  3  in the vicinity of the first when the lid  20  is open. 
         [0061]    Stability in the open position C can also be achieved with a mass difference between the lid  20  and the rod  22  causing an imbalance of moments that tend to leave the lid  20  in a retracted position C.