Field of the invention

The present invention relates to user-adjustable furniture, more particularly a height-tilt- adjustable office desk, and a method of adjusting such furniture. Another example of such furniture is a manufacturing workstation like in an assembly line where a work product needs to be positioned with respect to an operator.

Background art

Working stations with an adjustable height are known from the prior art. To that end, electronically adjustable office furniture is provided, such as sit-stand desks, drawing tables, or office chairs.

US 2018/0235360 A1 shows one such workstation having an adjustable height. The workstation has a top workspace area and a movable base consisting of two or four legs, wherein each movable leg includes a linear actuator mechanism and a power box. The power box controls the movement of the linear actuator mechanism which further controls the movement of the legs such that the workstation can be raised and lowered on command.

CN203467932U relates to a table, which comprises a tabletop and table legs, wherein each table leg comprises an upper table leg and a lower table leg, each upper table leg is connected with the tabletop through a hinge, a telescopic structure is arranged between each upper table leg and each lower table leg and is used for enabling each upper table leg to extend and retract relative to each lower table leg, and the bottom of each lower table leg is provided with a pulley which is provided with a brake mechanism.

A problem experienced with the known adjustable office furniture as well as assembly line workstations is that the height-adjustment may lead to user’s discomfort when switching from for example, a seated position to a standing position or from performing one type of task such as typing on a computer to another such as drawing. In many cases, change of height of a tabletop is not sufficient enough to provide a satisfactory adjustment for the user as it would still require from the user to assume an uncomfortable body position. Further, the stability of the table systems with adjustable tabletops is of key importance for such systems. Any adjustment mechanism that would result in unbalanced, shaky, wobbly, or in general unstable tabletops would render such systems impractical. Therefore, it would be desirable to provide electronically adjustable office furniture, which improves on existing furniture by providing additional adjusting options to the tabletop while maintaining the stability of the tabletop.

Summary of the invention

According to a first aspect of the present invention, a desk is provided as defined in claim 1 . The desk comprises a desktop, a pair of powered lifting columns for altering a vertical height of the desktop, wherein the pair of lifting columns are hingeably fixed to the desktop for allowing an inclined position of the desktop, and a support structure for maintaining at least one of the lifting columns in a stationary orientation, in particular an upright position.

The term “desk” in the context of this application may be understood in its broadest meaning as to mean a piece of furniture comprising a flat surface, the desktop, elevated from the such as a bureau, a sit-stand desk, a drawing desk, a counter, a workstation in an assembly line and similar. The desktop is elevated in a vertical direction from the ground by the lifting columns or legs of the desk. The vertical direction is a direction perpendicular to the ground, or a surface of a floor, or in general, a subsurface of the desk. The vertical height of the desktop is measured as a vertical distance of the desktop from the ground. In particular, the desk according to the present invention is configured for altering the vertical height of the desktop between a seating configuration and a standing configuration. In the seating configuration, the vertical height of the desktop is arranged to optimize performance of user’s tasks while the user is in a seated position. In the standing configuration, the vertical height of the desktop is arranged to optimize performance of the user’s tasks while the user is in a standing position.

The inclined position of the desktop is understood as tilted position of a surface of the desktop with respect to the ground wherein, the inclined position is characterized by a tilt angle enclosed by the surface of the desktop and the ground.

The upright position of the powered lifting columns is understood as a position wherein, a central axis of each of the powered lifting columns is aligned with a vertical direction.

The lifting columns are powered by a motor such as an electric motor, more precisely a de motor, or a pneumatic-motor or similar. Each of the lifting columns may have a motor and additionally all or at least some motors may be arranged to be synchronized. Preferably, each motor works independently, which facilitates adjusting of the position including the angular orientation of the desktop.

The support structure a support structure for maintaining at least one of the lifting columns in a stationary orientation, in particular an upright position. Usually, the support structure maintains both of the lifting columns in a stationary orientation, or even all of the lifting columns of the desk.

The desk according to the invention provides electronically adjustable furniture, which improves on existing furniture by providing additional adjusting options to the tabletop while maintaining the stability of the tabletop because of the support structure that maintains a lifting column in a stationary orientation while the lifting column is hingeably fixed to the desktop. This is beneficial in the office as well as for a workstation in an assembly line where a work product must be frequently positioned with respect to an operator in a stable manner.

In an embodiment, the support structure comprises a base frame contacting the subsurface of the desk. The support structure may comprise a pair of beams extending in a direction perpendicular to the vertical direction and having a length dimension configured to maintain the lifting columns in the upright position. Unlike the prior art, wherein the lifting columns are in a direct contact with the subsurface of the desk, the presence of the support structure improves the overall stability of the desk according to the present invention while allowing for a significant level of control of the position of the desktop as it will be apparent from the present disclosure.

In an embodiment, at least one lifting column of the pair of powered lifting columns comprises a stationary section. The stationary section may be hingeably coupled to the base frame. A hingeable connection between the base frame and the at least one lifting column is advantageous as it allows pivotal movement of the lifting column and the desktop to a desired height and/or inclination. Importantly, one of the lifting columns comprises the stationary section hingeably coupled to the base frame. This embodiment allows the user additional degrees of freedom in controlling the position of the desktop.

Alternatively, the stationary section may be fixedly connected to the base frame and the at least one lifting column of the pair of powered lifting columns may comprise a height adjustable section slideably fixed or connected to the desktop. A slidably fixed connection of the stationary section leads to an improved stability of the desk while the connection being slideable with the desktop allows for a suitable adjustment of the position of the desktop. Importantly, one of the lifting columns comprises the height adjustable section slideably fixed or connected to the desktop which results in maximal degree of freedom in controlling the position of the desktop while improving the overall stability of the desk.

In an embodiment, the desk according to the present invention comprises a desktop support frame contacting the desktop. The desktop support frame may be connected to the desktop by a bottom surface of the desktop, wherein the bottom surface is a surface of the desktop facing the subsurface of the desk. The desktop support frame may comprise two elongated elements placed at a distance between each other and close to peripheries of the desktop. For example, in a case of a rectangular shape of the desktop having a width dimension and a length dimension, the two elongated elements may be placed along the width of the desktop and separated mutually by approximately a value of the length of the desktop.

In an embodiment, at least one and preferably all lifting columns are hingeably and/or slideably coupled to the desktop through the desktop support frame.

In an embodiment, one lifting column of the pair of powered lifting columns is slideably fixed to the desktop through a slotted hole connection. The slotted hole connection is arranged to allow sliding of the desktop along a length of the slotted hole while a width of the slotted hole is configured to prevent an offset motion of the desktop in a perpendicular direction to a direction along the length of the slotted hole. This preventing of offset motion improves stability of the desk during the position adjustment of the desktop. Additionally, one of the lifting columns may be coupled to the desktop through the slotted hole connection arranged with the desktop support frame. The slotted hole connection may comprise one or more of the following: a bolt with a nut, t-slot fasteners, a Chicago screw, or similar type of fasteners.

The stability of the desktop may be further improved by using the slotted hole connection comprising prestressing means operational to avoid mechanical backlash between the at least one lifting column and the desktop. Preferably, each of the slotted hole connections comprises the prestressing means. The prestressing means are arranged in a form of a fastener, such as a screw, comprising a resilient member such as a spring. The fastener may include a head section comprising two flanges which are separated by the resilient member. The resilient member is configured to create a force in the perpendicular direction and efficiently suppress the offset motion of the desktop.

In an embodiment, the support structure interconnects the pair of lifting columns for maintaining the pair of lifting columns in the stationary orientation, in particular the upright position. Preferably, the support structure is self-supporting wherein, the self-supporting means that the support structure is configured to at least support weight of the desktop and the lifting columns. The support structure may comprise at least one of the following materials: a metal or wood, or plastic, or any other suitable type of material. An interconnection may be in a form of an interconnecting beam connecting the base frame with both columns of the pair of lifting columns.

In an embodiment, each lifting column of the pair of powered lifting columns comprises respective height position sensing means for determining a vertical height of the respective lifting column. The sensor may be in a form of a digital encoder configured to count rotational pulses provided by the motor.

In an embodiment, the desk may comprise two pairs of lifting columns arranged at opposite ends of the desk. This configuration with four columns is usual for desks. Each of the lifting columns may be powered by a motor. However, it is conceivable that associated lifting columns of the two pairs of lifting columns may be powered by a common motor. Like for example two associated lifting columns at the front of the desk, that is closest to a user of the desk, may be powered together. Likewise, two associated lifting columns at the back of the desk, that is furthest from a user of the desk, may be powered together.

In an embodiment, the desk may comprise a control unit for controlling a position of the desktop, wherein the position includes a height position and an angular position. The pair of lifting columns may comprise a primary lifting column and a secondary lifting column, wherein the primary lifting column further comprises a primary height position sensing means providing a primary height position signal, and the secondary lifting column comprises a secondary height position sensing means different and independent from the primary height position sensing means and providing a secondary height position signal. Both, the primary height position sensing means, and the secondary height position sensing means may be operationally coupled to the control unit. The control unit may be configured to control the height position of the desktop based on the primary height position signal and, additionally or alternatively, the angular position of the desktop based on a difference between the primary height position signal and the secondary height position signal. In an embodiment, the first pair of lifting columns may comprise the primary height position sensing means, and the second pair of lifting columns may comprise the secondary height position sensing means. Further, the first pair of lifting columns may provide the primary height position signal and the second pair of lifting columns may provide the secondary height position signal.

In an embodiment, the primary height position sensing means and/or the secondary height position sensing means comprises a rotary sensor. The rotary sensor may be in a form of a digital encoder. Additionally, the desk may comprise an electric motor powering one of the primary lifting column and secondary lifting column, and wherein the rotary sensor is operationally coupled with the electric motor for counting a number of motor shaft revolutions.

In an embodiment, the desk may comprise an input unit coupled with the control unit, wherein the input unit is configured to receive a single user instruction associated with both the height position and the angular position. In a further embodiment the desk may comprise a memory unit, wherein the memory unit is configured to store pre-sets of height positions and angular positions defined by the user and/or manufacturer.

According to a second aspect of the present invention there is provided a method for controlling a position of the desktop of the desk according to the first aspect of the present invention. The method comprises steps of controlling a height position of the desktop based on the primary height position signal, and controlling an angular position of the desktop based on a difference between the primary height position signal and the secondary height position signal.

In an embodiment, the method may additionally comprise powering the primary lifting column and the secondary lifting column of the pair of lifting columns for simultaneously controlling the height position and the angular position of the desktop.

In an embodiment, the method may comprise step of powering at least one of the primary lifting columns and the secondary lifting column until an extreme position is taken, and then setting a corresponding at least one of the primary height position signal and secondary height position signal to an initial value.

In an embodiment, the method may further comprise step of driving the primary lifting column and the secondary lifting column at different speeds. In a further embodiment, the method further comprises step of the desktop reaching a set height position and set angular position at the same time as perceived by a user of the desk. Additionally, in case the angular position exceeds a user acceptable value, the method may comprise interrupting of powering of at least one of the primary lifting columns and the secondary lifting column, and/or powering of at least one of the primary lifting columns and the secondary lifting column in an opposite direction.

Short description of drawings

The present invention will be discussed in more detail below, with reference to the attached drawings, in which

Fig. 1 depicts a perspective view of a desk according to the present invention;

Fig. 2 depicts a side-view of the desk in Fig. 1 ;

Fig. 3 depicts an enlarged area around a slotted hole connection of the desk shown in Fig. 2;

Fig. 4 depicts a side-view of the lifting column configuration of the desk according to the present invention;

Fig. 5 depicts a side-view of a lifting column with a hingeable connection of the desk according to the present invention;

Fig. 6 depicts an enlarged area around a slotted connection shown in Fig. 4; and

Fig. 7 depicts a control unit of the desk according to the present invention.

The figures are meant for illustrative purposes only, and do not serve as restriction of the scope or the protection as laid down by the claims.

Description of embodiments

The following is a description of certain embodiments of the invention, given by way of example only and with reference to the figures. In the drawings, like numerals designate like elements. Multiple instances of an element may each include separate letters appended to the reference number. For example, two instances of a particular element “20” may be labeled as “20a” and “20b”. The reference number may be used without an appended letter (e.g., “20”) to generally refer to an unspecified instance or to all instances of that element, while the reference number will include an appended letter (e.g., “20a”) to refer to a specific instance of the element.

Fig. 1 depicts a perspective view of a desk 10 according to the present invention. The desk 10 has a desktop 12, four lifting columns 14, and a support structure in a form of a base frame 16. The desktop 12 has a bottom surface B facing a ground G and an opposite top surface T which is facing a user. The base frame 16 includes two base frame beams 18 which are in contact with a ground G. Each of the lifting columns 14 comprises a stationary section 22 connected to the base frame 16 and a height adjustable section 24 connected to the desktop 12. The height adjustable section 24 and the stationary section 22 partially overlap such that the height adjustable section 24 is placed over the stationary section. The height adjustable section 24 and the stationary section 22 do form a telescopic lifting column 14.

Fig. 2 depicts a side-view of the desk 10 shown in Fig. 1. The desktop 12 further includes a desktop support frame 26 connected to the bottom surface B of the desktop 12. The base frame 18 includes a pair of stabilizing feet 34 for stabilizing the base frame 16. A first lifting column 14A is connected to the desktop support frame 26 by a hole connection 28 allowing a pivotal movement of the desktop 12 around the hole connection 28. A second lifting column 14B is connected to the desktop 12 by a slotted hole connection 32. The first lifting column 14A and the second lifting column 14B are separated by a distance D. The first lifting column 14H has a height H that can be increased or decreased by sliding the height adjustable section 24A of the first lifting column 14A up or down, with respect to a vertical direction Z, the stationary part of the first lifting column 14A, respectively. The same applies to the second lifting column 14B. A difference AH between the heights of the first lifting column and the second lifting column defines an inclination of the desktop 12. The inclination is characterized by an inclination angle a. The slotted hole connection 32 is shown in more detail in Fig. 3.

Fig. 3 depicts the enlarged area III around the slotted hole connection 32 in Fig. 2. The slotted hole connection 32 comprises a slot 36 in the desk support frame 26 and a bolt 38. The bolt 38 is inserted thorough the slot 36 and a corresponding slot (not shown) in the second lifting column 14B and fastened on an opposite end by a nut (not shown). The fastening is arranged to allow a translatory movement of the desktop 12 with respect to the second lifting column 14B. During the inclination adjustment motion, the second lifting column 14B moves along the vertical direction Z. In this process, the bolt 38 moves along the slot 36 from one end of the slot 36 towards the other end of the slot 36 and the inclination angle a of the desktop 12 is changed. A width W of the slot 36 is arranged to correspond to a width of the bolt 38 in order to minimize an offset motion of the desktop 12 resulting in an improved stability of the desktop 12 in use.

Fig. 4 depicts another embodiment of the position adjustment mechanism of the desk 10’. In this embodiment, the desk 10’ has lifting columns 14 which each comprise height position sensing means 44 that measure a vertical height of the respective lifting column 14 along a central axis 42. In the position adjustment process of the desktop 12, the height adjustment section 24 slides along the stationary section 22 until a set or desired position of the desktop 12 is reached.

Fig. 5 depicts another embodiment of the desk 10” according to the present invention wherein the second lifting element 14B is connected to the base frame 18 by a hingeable connection 46. The hingeable connection 46 allows the second lifting element 14B to preform a pivotal motion P around the connection in order to enable the inclination of the desktop 12.

Fig. 6 depicts the enlarged area VI shown in Fig. 4. The figure shows the slotted hole connection 32’ comprising a prestressing means 48. The prestressing means 48 includes a fastener 48 having a split head section 54 and a spring 52 therein between. The spring 52 is inserted in order to push sections of the slit head section 54 towards edges of the slot 36 along the width W and prevent the undesirable offset motion leading to instabilities of the desktop in use.

Fig. 7 depicts a control unit 62 of the desk according to the present invention. The control unit includes two de motors 64 powering independently two lifting elements (not shown), a height sensor 66, and a user controller 68. The user sends instructions via the user controller 68 which are handled by the control unit 62 instructing the motor 64 to start height adjustment process. The sensor 66 counts the rotation cycles of the motor 64 in order to obtain height information and sends signals back to the control unit 62. Once, the desired position of the desktop 12 is achieved, the control unit 62 ends the process.

The desk control unit provides the ability to control both, the height adjustment of the desk according to the present invention, as well as the inclination. The height of each lifting column 14 is measured by rotational pulses provided by the de motor 64. For initializing the desk before first use, a calibration before adjustment is done to determine the absolute null I block position of each lifting column 14. To achieve this, the motor 64 drives slowly down to the lowest possible position until a mechanical stop creates a certain resistance causing a spike in electrical current that provides the control unit 62 with the information that the mechanical lowest limit or in other words the null I block position has been reached.

The desk control unit 62 operates the first and the second lifting column independently. An offset of the pulses of the motor 64 powering the second lifting column 14B with respect to the pulses of the motor 64 powering the first lifting column 14B axis is used to control the inclination of the desktop 12.

Pre-defined positions of the desktop 12 are stored in the desk control unit 62 and recalled using the user controller 68. For example, the control unit 62 has a current position “A” that comes with the height of the first lifting column 72cm and inclination: 0°. The user can change these parameters by instructing the control unit 62 to apply a predefined position “B” pre-set to the height of the first lifting column 90cm and inclination 30°.

The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible and are included in the scope of protection as defined in the appended claims.