Patent Application
20140239692
This application claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2013 102 008.9, filed Feb. 28, 2013; the prior application is herewith incorporated by reference in its entirety.
1. Field of the Invention
The invention relates to a mechanism for an office chair.
Numerous techniques for changing the movement characteristic of an office chair mechanism are known from the prior art. The movement is generally a pivoting movement. Depending on the mechanism being used it may, for example, be a combined synchronous seat/backrest movement or an asynchronous seat/backrest movement. Other movements that are realizable by an office chair mechanism are, for example, the adjustment of the seat inclination independently of the backrest inclination or the adjustment of the backrest inclination independently of the seat inclination.
In that case, an adjusting device for changing the movement characteristic of the mechanism frequently includes one or more spring configurations (for example in the form of a plurality of compression or tension springs connected in parallel) and associated setting mechanisms (worm gears, gear wheels, threaded rods, etc.). If, for example, the pivoting resistance of the backrest of an office chair is intended to be changed, the tension of the spring elements is usually changed with the aid of a manually operable actuating element, for example a handle or crank, and thus a setting between “hard” and “soft” is selected, depending on whether the user of the office chair is a heavy or light person.
Changing the movement characteristic of the office chair mechanism, in particular for example the pivoting resistance of the backrest, in this case is often associated with the exertion of a comparatively high force.
It is accordingly an object of the invention to provide a mechanism for an office chair, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known mechanisms of this general type and which simplifies the manipulation of an adjusting device for changing a movement characteristic of an office chair.
With the foregoing and other objects in view there is provided, in accordance with the invention, a mechanism for an office chair, comprising an adjusting device for changing a movement characteristic of the mechanism, in particular for changing a pivoting resistance of a backrest of the office chair, and an electromotive drive configured to actuate the adjusting device.
It is a core concept of the invention to use an electromotive drive to actuate the adjusting device. As a result, the manipulation of the adjusting device is considerably simplified, since manual operation of an actuating element, associated with the exertion of a comparatively high force, is no longer required. Instead, the user can manipulate the adjusting device without physical effort.
In addition, the use of an electromotive drive for actuating the adjusting device opens up a multiplicity of further options for improving the office chair mechanism, in particular in connection with changing the movement characteristic of the mechanism. Thus, the movement characteristic can be adapted, for example automatically and without the user being involved, to particular properties of the user and/or to the user's behavior, as is explained in more detail further below.
In accordance with another feature of the invention, the mechanism includes an actuating element for actuating the adjusting device. This actuating element is connected to the electromotive drive and is driveable by the electromotive drive. In a very simple case, the actuating element is a spindle. The actuating element is connected to the drive preferably directly, that is to say without interposition of an additional component. Complicated setting mechanisms, such as worm gears, gear wheels, threaded rods, etc., are not necessary as a rule. Therefore, the number of components and the manufacturing costs are particularly low.
In accordance with a further feature of the invention, the adjusting device includes a spring configuration having at least one spring element, and the spring configuration is operatively connected to a backrest support of the office chair and determines the pivoting resistance of the backrest support in the event of pivoting from a starting position into a pivoted position. In this case, the actuating element is configured to change the tension of the at least one spring element and/or to change the spring rate (also called spring stiffness, spring hardness or spring constant) of the spring configuration.
The spring configuration operatively connected to the backrest support of the office chair can be connected either directly or indirectly to the backrest support. In the event of indirect connection, the spring configuration is connected to the backrest support preferably through the seat support as a coupling element. The specific structural embodiment is dependent on the construction of the office chair and the type of mechanism (synchronous mechanism, asynchronous mechanism).
The tension of the at least one spring element and/or the spring rate of the spring configuration is changed by way of the actuating element, in particular by way of a change in position of the actuating element, for example a movement of the actuating element in translation or rotation. For the purposes of the present invention, any desired types of spring element can be used in the spring configuration. Helical springs in the form of leg springs, helical compression springs or helical tension springs have proven particularly advantageous due to their simplicity and robustness.
In this case, it is left to the specific configuration of the mechanism as to whether one or more spring elements are tensioned or relaxed when the pretensioning of the spring configuration is set. In other words, for example, on one hand a spring element which is completely or partially relaxed in the unloaded state of the office chair can be tensioned in the event of loading, or on the other hand a spring element which is maximally or partially pretensioned in the rest state relaxes when the office chair is loaded. However, active forcing of the mechanism counter to the movement of the backrest by a number of already pretensioned spring elements preferably already takes place even when the seat support is not loaded by a user. It is likewise left to the specific embodiment of the invention as to whether the spring rate of one or more spring elements is changed and how the change of the spring rates takes place.
The pretensioning of individual spring elements and the spring rate of the spring configuration can be set fundamentally in two different manners. Firstly, it is possible to change the position of at least one spring end of a spring element of the spring configuration with the overall position of the spring element staying the same or changing. This can take place for example by the spring ends of a helical spring being pulled apart or pushed together or by rotation or deflection of one spring leg of a leg spring towards the other spring leg or relative to the other spring leg, about the spring longitudinal axis extending through the spring midpoint. Secondly, it is possible to change the position of the spring element itself relative to its fixed or likewise at least partially movable spring ends. In the case of a leg spring, this can take place for example by displacement of the spring midpoint of the leg spring, when the bearing points are fixed. Depending on the requirements placed on the structure of the seat mechanism, both variants of spring setting can be realized in the case of the invention. In order to change the spring rate of the spring configuration, it is also possible for example to change the number of spring elements that act in the spring configuration.
The invention is not limited to the use of a spring configuration for changing the movement characteristic. Instead of a spring configuration, the adjusting device for changing the movement characteristic may also include other components. Thus, for example, instead of a spring configuration, a variable cam mechanism can be used. What is important is that the adjusting device or the actuating element of the adjusting device is actuated by an electromotive drive.
In a simple embodiment of the invention, the adjusting device is actuated by the electromotive drive in that the drive is operated by the user, in particular switched on and off. However, an embodiment of the invention in which the movement characteristic is changed automatically and without the user being involved has proved to be particularly advantageous.
In accordance with an added feature of the invention, the mechanism preferably includes at least one measuring device for detecting at least one user-dependent measured value and also an evaluation and control unit for evaluating the measurement result and for controlling the electromotive drive depending on the measurement result. In other words, the electromotive drive of the adjusting device is controlled on the basis of measured values which are detected in direct temporal conjunction with the use of the office chair. As a result, an individual movement characteristic, matched to the user, of the office chair mechanism is settable.
For this purpose, in an embodiment of the invention, the evaluation and control unit includes a microcontroller or some other computing unit suitable for data processing, and a memory in which a characteristic curve is stored. With the aid of the characteristic curve, particular control values for controlling the adjusting device are assigned to possible measured values. For example, defined spring-force settings are assigned to various user weights. In this case, it may be a conventional linear characteristic curve or a non-linear characteristic curve. Taking the actually determined measured values into account, the evaluation and control unit selects, from the characteristic curve defining the movement characteristic of the mechanism, the associated control values according to which the electromotive drive is subsequently controlled. To this end, a corresponding control signal is generated which causes the electric motor to move to a position associated with the control signal.
In an embodiment of the invention, different characteristic curves are stored in the evaluation and control unit. In this case, it is advantageous for automatic selection of a characteristic curve which is suitable for the current user or is preferred to take place. A suitable characteristic curve is selected for example on the basis of the results of the measurements of the measuring device that are taking place. A preferred characteristic curve is selected for example on the basis of identification of the current user. In another variant, the user has the possibility of selecting a particular characteristic curve.
In accordance with an additional preferred feature of the invention, the measuring device and the evaluation and control unit are configured to continuously measure, evaluate and control. In this case, not only user-individual control of the drive can take place but also continuous control of the drive which is thus matched dynamically to the current, actual loading of the chair. If a plurality of characteristic curves are available for selection, it is also possible in this case to change the characteristic curve if the evaluation of the measurement results reveals that the currently used characteristic curve is providing a movement characteristic which is not optimal for the user.
As an alternative to a continuous mode of operation, the mechanism may also be configured in such a way that the setting of the movement characteristic, for example the setting of the spring force for pivoting the backrest, takes place once, when the user sits down on the seat of the office chair. The setting is then initiated preferably by the actuation of an operating element by the user, for example by the actuation of a button or the like. However, the one-time setting of the movement characteristic can also be initiated automatically when the user sits down on the seat.
In accordance with yet another feature of the invention, the at least one measuring device includes a device for measuring the weight of a user sitting on the office chair.
In accordance with a concomitant feature of the invention, the at least one measuring device, alternatively or additionally to measuring the weight, includes a device for detecting the weight distribution and/or for detecting the position of the user on the seat of the office chair.
The selection of the control values, suitable for the user, for controlling the electromotive drive with the aid of the characteristic curve then takes place preferably both with the weight of the user being taken into account and with the weight distribution of the user on the seat of the office chair, and thus his or her sitting position, being taken into account. In other words, the mechanism is set preferably automatically depending on the weight, the weight distribution and/or the position of the user. As a result, an optimal movement characteristic can be selected from ergonomic points of view.
It is particularly advantageous if, in addition to the movement characteristic, influenced by the evaluation and control unit, of the office chair, selected control values for controlling the electromotive drive are settable by the user in advance on the chair, or on the mechanism, and/or are manually changeable subsequently, or while sitting. As a result, for example a movement characteristic that is perceived to be uncomfortable can be altered by the user. If the user wishes to operate the electromotive drive and/or the evaluation and control unit, the drive or the evaluation and control unit can be operated preferably with the aid of suitable operating elements, for example buttons and/or touch-sensitive surfaces.
The device for measuring the weight of the user is preferably at least one force sensor or the like, which is advantageously installed under the seat of the office chair. In order to measure the weight of the user, it is also possible to provide a plurality of force sensors or the like that are disposed in a spaced-apart manner.
The device for detecting the weight distribution is preferably a number of force sensors or the like, which are disposed in a spaced-apart manner. If both the weight and the weight distribution are intended to be detected, both devices advantageously make use of the same sensors.
The device for detecting the position of the user is advantageously a device which has recourse to the measurement data of the weight distribution and determines the position of the user therefrom. However, the device for detecting the position of the user may also, independently of the force sensors or pressure sensors which may already be present, be a number of touch sensors disposed in or on the seat, wherein these touch sensors react for example to mechanical contacts and/or temperature fluctuations brought about by the user.
In principle, no limits are placed on the type of sensors and measuring devices that are used. What is important is that the measuring devices used provide measured values that are dependent on the individual user of the office chair and are relevant for changing the movement characteristic of the mechanism in a user-individual manner.
Thus, by way of the invention, a system for changing the movement characteristic of an office chair mechanism, in particular for example for changing the pivoting resistance of the backrest of an office chair, is created, with the system being set without the user being involved and differing from the systems known from the prior art in that the movement characteristic, in particular for example the pivoting resistance, is primarily not set arbitrarily by the hand of the user, but automatically and in accordance with the specifications of the mechanism, in particular in accordance with the control unit of the mechanism and the calculations that take place there or the characteristic curves stored there. It is primarily advantageous in this case that it is possible to change the movement characteristic, in particular for example the pivoting resistance, in a particularly simple, reliable and safe manner. The movement characteristic can, in this case, not only be set in dependence on the weight of the user but also in dependence on the sitting behavior of the user.
The invention can be used in numerous office chair mechanisms, irrespective of whether it is a synchronous or asynchronous or some other form of mechanism.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a mechanism for an office chair, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now in detail to the figures of the drawings, all of which are diagrammatic, not true to scale and only show important constituent parts and in which identical reference signs correspond to elements having an identical or comparable function, and first, particularly, to
Mounted on the seat support 3 is a seat 10, which is provided with an upholstered sitting surface. Fitted on the backrest support 4 is a non-illustrated backrest, which is height-adjustable in modern office chairs. The backrest can also be connected integrally to the backrest support 4.
It is understood that such a description of the mechanism 1 serves merely to identify the important structural components. A person skilled in the art is familiar with the further structure of an office chair mechanism.
The mechanism 1 includes an adjusting device 6 for changing its movement characteristic. An electromotive drive 7 is used to actuate the adjusting device 6. This electromotive drive 7 is, for example, a commercially customary electric motor having a gear mechanism, which is operated through a mains connection or by batteries or rechargeable batteries.
The mechanism 1 includes an actuating element in the form of a spindle 8 for actuating the adjusting device 6. The spindle 8 is directly connected to the electric motor 7 and is driveable by the electric motor 7.
The adjusting device 6 includes a spring configuration 5 for forcing the mechanism 1 counter to the movement of the backrest support 4. The spring configuration 5 includes at least one spring element in the form of a compression spring 9. The spring configuration 5 is connected indirectly to the backrest support 4 of the office chair, with the seat support 3 serving as a coupling element. The spring configuration 5 determines the pivoting resistance of the backrest support 4. In this case, the spindle 8 is configured to change the pretensioning of the compression spring 9. To this end, the spindle 8 acts directly on a spring seat 11 of the compression spring 9. The spring seat 11 is adjustable in the longitudinal direction of the spring. An opposite spring seat 12 is mounted in a non-movable manner. Thus, a rotation of the spindle 8, brought about by the electric motor 7, results in a reduction in the distance between the two spring seats 11, 12.
The mechanism 1 includes a measuring device 13 having a plurality of load cells 13 disposed in a spaced-apart manner beneath the seat, to be more precise beneath the seat panel, for detecting the weight of the user. Force transducers can also be used instead of load cells 13.
The mechanism 1 furthermore includes an evaluation and control unit 14 for evaluating the measurement results of the measuring device 13 and for actuating the electric motor 7 in dependence on the measurement results. In this case, the measured values determined by the load cells 13 serve in the evaluation and control unit 14 to simultaneously determine the weight distribution and thus to detect the position of the user on the seat.
The evaluation and control unit 14 includes a microcontroller 15 and a non-illustrated memory, in which a characteristic curve of the mechanism is stored. This characteristic curve assigns one or more control values for controlling the electric motor 7 to each weight and each sitting position.
In a simple example, the microcontroller 15 receives an analogue voltage signal from the load cells 13 and determines therefrom the weight and the sitting position of the user. Furthermore, the microcontroller 15 receives a signal from the electric motor 7 about the current position of the spindle 8. For this purpose, the electric motor 7 is equipped with a suitable non-illustrated position sensor. The microcontroller 15 contains in its program sequence a characteristic curve which assigns a defined spring force setting to each weight/position combination. The microcontroller 15 selects the corresponding control values depending on the weight and the sitting position of the user. The evaluation and control unit 14 uses these control values to control the electric motor 7 and a corresponding control signal is output to the electric motor 7. A suitable control loop causes the electric motor 7 to move into the position calculated by the microcontroller 15. The measuring, evaluating and controlling takes place continuously in this case, starting at the time at which the user sits down on the seat of the office chair.
The load cells 13 or force transducers mentioned in conjunction with the described exemplary embodiment typically use strain gauges to register elastic component deformations. However, it is also possible to use other suitable sensors. Rather than prefabricated assemblies, the strain gauges or other suitable sensors can also be used as individual components. Thus, a strain gauge can be encapsulated, for example, by a plastics seat panel of the seat or a strain gauge is attached to the housing of the mechanism 1. Individual sensors or assemblies, for example force transducers, may also be installed between components of the chair, as long as such a configuration is suitable for detecting user-individual measured values, for example between gas spring and base support 2 or between gas spring and foot cross.
It is also not necessary for the sensors to be fitted in or on the seat of the office chair. Thus, the weight of the user or a change in the sitting position can, for example, also be detected in that a pressure sensor senses a rise in pressure within a gas spring fitted in the chair column.
In addition to the above-described applications, further applications for an electromotive drive come into question in an office chair.
Thus, for example, a variable travel limitation can be brought about by way of the electromotive drive, as is depicted in
An electromotive drive can also be used to actuate a gas spring 34 of the office chair.
Another variant for actuating a gas spring 34 is depicted in
All of the features illustrated and discussed in the description, the following claims and the drawing can be important to the invention both individually and in any desired combination with one another.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102013102008.9 | Feb 2013 | DE | national |
