Energy-independent height indicator for a table

Abstract

Height indicator device (22) for a height-adjustable table (10), comprising - a sensor (24) for measuring a height (26) of a table top (18); - a display (34) for indicating the height (26); - an energy generator (36) for generating electrical energy to operate the sensor (24) and the display (34).

Description

BACKGROUND OF THE INVENTIONThe invention relates to a height display device for a height-adjustable table, having a sensor for measuring a height of a table top and a display for displaying the height.Such a height display device is known, for example, from WO 2019 / 086071 A2.In the case of tables that can be adjusted vertically by electric motor, as are known, for example, from the aforementioned WO 2019 / 086071 A2, the energy supply of the sensor and display is possible without problems via an electrical network, which also supplies the energy for driving the adjusting motor for adjusting the height.There is an increasing need for height-adjustable tables which do not have electric motors and do not require an external power supply. It is known in principle in this respect to provide gas compression springs to assist the height adjustment.In such mechanically height-adjustable tables, however, the adjusted height of the table top cannot be displayed easily or often not released in a sufficiently comfortable manner. Accurate or repeatable adjustment of a particular height is therefore cumbersome.If a height scale is attached to a table leg, it is difficult to read.Devices with a pointer which is controlled via a cable pull are structurally complicated and correspondingly expensive. Furthermore, these cannot be retrofitted as a rule.Object of the InventionIt is an object of the invention to improve the comfort when using, in particular, mechanically height-adjustable tables.DESCRIPTION OF THE INVENTIONThis object is achieved according to the invention by a height display device according to claim 1 and according to claim 10, a table according to claim 16 and a table assembly according to claim 27.Height Display Device According to the InventionAccording to the invention, a height display device for a height-adjustable table is provided. The height display device is also referred to below for short as height display.The height display has a sensor for measuring a height of a table top and a display for displaying the height. The sensor can be arranged at a defined distance from an upper side of the table top. The displayed height can then be obtained from the measured value of the sensor by corresponding addition or subtraction of the distance and, if appropriate, of the height of a reference surface with respect to which the sensor measures. The sensor is typically a distance sensor.According to a first aspect of the invention, the height display device has an energy generator for generating electrical energy for operating the sensor and the display. The energy generator enables the operation of the height indicator independently of a power grid. As a result, the height of a mechanically adjustable table can be measured precisely and displayed in a well-readable manner.The height display device according to the invention can advantageously be easily retrofitted to an existing table, in particular since no electrical connection is required. This also makes it possible, when manufacturing mechanically height-adjustable tables, to dispense with the height display depending on the customer's desire in order to save costs, or to attach the height display in order to increase the ease of use, in particular without the other components of the table having to be changed for this purpose.The height display device can furthermore have an energy store for electrical energy generated by the energy generator, in particular a capacitor and / or an accumulator. The energy store can compensate for a time offset between the power generation in the energy generator and the power requirement of the sensor, display and, if appropriate, of a control device. If an accumulator is provided as an energy store, it is basically only charged by the energy generator and not with the aid of a power network. Likewise, it is not provided to replace the accumulator with a charged accumulator.The energy generator can have a solar module. The usual illumination in the office environment makes it possible to generate sufficient energy even with relatively small solar modules. This applies in particular when an e-paper display is used. A surface area of the solar module can be at least 1 cm 2, in particular at least 2 cm 2 or at least 4 cm 2 and / or at most 20 cm 2, preferably at most 15 cm 2, particularly preferably at most 10 cm 2. This simplifies the integration of the energy generator with sufficient performance.The height display device can have an operating element, in particular for triggering a height adjustment of the table. The energy generator can be attached to the operating element in order to generate electrical energy when the operating element is actuated. In this way, a manual movement to be carried out anyway during the height adjustment can be used to provide the energy for the height measurement. It can also be provided that the actuation of the operating element triggers a measurement process independently of the height adjustment.The energy generator can have a piezoelectric element. A piezo element is particularly suitable for generating energy during a manual actuation process such as the movement of an operating lever for height adjustment.The energy generator can have a generator, in particular with a permanent magnet movable relative to a coil. The relative movement can take place rotationally or linearly or along a curved path. The generator can be driven by a manual actuation process, for example the movement of an operating lever for height adjustment, or a relative movement of components of a table frame. The latter allows the provision of a comparatively large amount of energy. In particular, the generator can be driven by changing the length of a telescopic table leg. Alternatively, the generator can be driven by a rotation of a synchronous shaft between two table legs of variable length.The height display device can furthermore have a control device, in particular a microcontroller, for actuating the sensor and the display. The control device is likewise operable with energy generated by the energy generator. In particular, the control device can be configured to actuate the sensor for height measurement at predefined time intervals, of for example 0.2 seconds, when the energy supply is present. The display can be updated after each measurement process. Preferably, the control device is configured to cause a change in the display of the display only if the height measured by the sensor has changed. Intermittent measurement and display update also reduces the power generator requirements. If no energy is available, the height display device can transition into a rest state, preferably wherein the height last displayed is still displayed on the display.The components of the height display device are typically all mountable on the table, in particular on the table top or a part of a table frame that is movable together with the table top, for example a cross member or a plate carrier.The sensor, the display, the energy generator and, if appropriate, the control device and the energy store can be combined in a single structural unit which can be mounted on a table top. This simplifies the assembly or retrofitting of the height display device. A housing of the common structural unit can have a recess for passing through a screw, an adhesive strip and / or a clamping section. In this way, the height display device can be screwed or glued to the table top or clamped to the table top.Alternatively, the energy generator can be mountable separately from the sensor and / or the display and / or the control device, in particular on an operating element for triggering a height adjustment or on a table frame. If provided, the energy store can be mountable together with the energy generator or together with the other components. Depending on the type of energy generator, in particular when the energy generator uses relative movements for generating energy, a separate, spatially separate mounting may be advantageous.It is also conceivable that the sensor can be mounted on the table top, in particular on the underside, while the display can be arranged on the table top or otherwise, for example on another piece of furniture or a furniture accessory, independently of the sensor. The energy generator can be mountable together with the display (in particular in the case of a solar module) or with the sensor or independently. The control device can be mountable with the display or with the sensor or with the energy generator.Components of the height display device which are spatially separated from one another can be wired to one another for the common energy supply, in particular by the energy generator, and / or for the data transmission.In a second aspect, the invention also relates to a height display device in which, instead of an energy generator or in addition to the energy generator, a replaceable battery is provided for supplying energy to the sensor, display and optionally control device. In this respect, the invention also relates to a height display device for a height-adjustable table, havinga sensor for measuring a height of a table top;a display for displaying the height;a replaceable battery for providing electrical power for operating the sensor and the display.The battery can further simplify the structure of the height display device. In the case of height display devices which are used only occasionally, a battery can have a sufficiently long service life.A control device, in particular of a battery-operated height display device, can be configured to perform a height measurement only on request, for example when an operating element for height adjustment or a switching element for triggering a measurement is actuated, and to display the measured height temporarily, for example for 10 to 30 seconds.The display is preferably configured to obtain its display value in a voltage-free state. The height set is thus displayed permanently or at least for a longer period of time of, for example, at least 10 hours, without energy being required for this purpose. This enables the use of a small and simple-constructed power generator. Accordingly, a replaceable battery is not loaded for display after measurement.In particular, the display can be an e-paper display. E-paper displays require energy only to change the display value. In the voltage-free state, the display value is retained. In addition, e-paper displays are easily readable and can be inserted into an office environment with a high-quality appearance.Alternatively, the display can be an LED display, in particular an OLED display. Such displays are available at low cost and can be operated with little energy. OLED displays can present particularly high contrasts for improved readability in brightly illuminated regions.It can be provided that the display, in particular the (O)LED display, displays the set height for a certain period of time, for example 10 to 30 seconds, after an adjustment process and then goes out. This reduces the requirements of the energy generator or the battery, in particular if the display requires continuous energy supply for the display.The sensor is preferably configured for contactless height measurement. The sensor can in principle be arranged in a fixed manner on the table top or a part of a table frame, for example a cross-member or a plate carrier, which is movable jointly with the table top; however, the sensor measuring in a contactless manner does not have any mechanical contact with a floor or a part of the table frame standing on the floor.The sensor is preferably an ultrasonic sensor. Ultrasonic sensors require very little energy. Ultrasonic sensors are also particularly suitable if the height of the table top with respect to soft or non-reflecting surfaces is to be measured, for example a particularly gray carpeting, as is frequently used in office environments.Alternatively, the sensor can be an optical sensor, in particular a laser sensor, a lidar sensor or a time-of-flight sensor. These sensors can make particularly accurate measurements possible. It can be provided that the optical sensor is aligned with a foot boom. The foot beam typically has favorable reflection properties for an optical measurement.A measuring direction of the sensor can be angled (in the correctly mounted state of the height display device) with respect to the vertical, for example by 3° to 5°, in particular away from the table top. This can prevent objects such as office containers arranged below the table top from distorting the measurement. It is understood that for displaying the measured height, a corresponding conversion of the measured value of the sensor takes place.Inventive TableThe invention further relates to a height-adjustable table having a table top, having a table frame, preferably having at least one table leg which can be varied in length, and having an above-described height display device according to the invention. Instead of a table leg that can be varied in length, a scissors mechanism could be provided, for example.The table can have a, preferably lockable, gas pressure spring for assisting the height adjustment. Preferably, the gas spring is arranged in the table leg. In such tables, a conveniently usable height measurement which is simple to install and operates precisely has not been known up to now.The display can be embedded in the table top. The table top can be provided with a recess for this purpose. Preferably, further, in particular all, components of the height display device are also embedded in the table top. An embedded display, which in particular ends flush with the table top, does not prevent the use of the table top for depositing objects. In addition, the integration protects against damage.The display can be arranged on a longitudinal side of the table top, in particular a user-side longitudinal side. This can be ergonomically advantageous for reading the display. For a particularly simple assembly, the display can overlap the longitudinal side of the table top, preferably with further components of the height display device.In particular, the entire height display device can be attached to the longitudinal side.The display can be arranged separately from the sensor. Typically, the sensor can be mounted on the table top, in particular on the underside. The display can be arranged at another location on the table top, in particular on the top, or on a furniture accessory, for example on an organization element or a separation element such as an optically and / or acoustically effective panel.Advantageously, the sensor is arranged on an underside of the table top. This enables accurate height measurement. In addition, the sensor does not interfere with the use of the table.A structural unit of the height display device comprising the display (and preferably the sensor and optionally the control device) can be screwed or glued to the table top or clamped to the table top. The structural unit can furthermore comprise the energy generator, in particular if it has a solar module; in the embodiment with a replaceable battery, it can also be arranged in the structural unit. The mounting of the height display device is possible in a particularly efficient manner in this embodiment.The sensor may be directed at a foot boom of the table leg. The foot boom can have favorable properties for contactless, in particular optical, height measurement. In particular, by measuring against the foot boom, the energy requirement for a height measurement can be reduced because of its favorable reflection properties.A measuring direction of the sensor can be angled with respect to the vertical, for example by 3° to 5°, in particular away from the table top. This can prevent objects such as office containers arranged below the table top from distorting the measurement. It is understood that for displaying the measured height, a corresponding conversion of the measured value of the sensor takes place.If the height display device has an energy generator, in particular a piezoelectric element or a generator, different types of drive are conceivable for the energy generator.The energy generator can be driven by an operating element for releasing a fixing of a table frame, in particular for releasing a blocking of the gas pressure spring. In this way, a manual movement to be carried out anyway during the height adjustment can be used to provide the energy for the height measurement.The energy generator can be driven by changing the length of a telescopic table leg. In particular, the energy generator can be mounted between two parts of the table leg that are movable relative to one another, in particular between two telescopic segments. "Intermediate" is to be understood here as functional and not necessarily spatially. This enables the use of an often large relative movement, which takes place with a certain force, for generating a comparatively large amount of energy.The table stand can have a synchronous shaft which couples the changes in length of two table legs. The power generator may be driven by the synchronous shaft. In this way, in particular a rotationally operating generator can be used to generate a comparatively large amount of energy.Table Assembly according to the InventionThe invention also relates to a table assembly with a height-adjustable table frame, preferably having at least one length-adjustable table leg, and with an above-described height display device according to the invention. By supplementing a table top, a table according to the invention described above can be obtained with the table assembly.Further features and advantages of the invention are evident from the description, the claims and the drawing. According to the invention, the features mentioned above and those set out further below can each be used individually or together in any desired suitable combinations. The embodiments shown and described are not to be understood as a final enumeration, but rather have exemplary character for describing the invention.DETAILED DESCRIPTION OF THE INVENTION AND DRAWINGThe invention is illustrated in the drawing and is described with reference to exemplary embodiments. FIG. 1 shows a schematic diagram of a table according to the invention with a height display device according to the invention in a first embodiment; FIG. 2 shows a schematic plan view of a height display device according to the invention of a table according to the invention in a second embodiment; FIG. 3 shows a schematic diagram of a table according to the invention with a height display device according to the invention in a third embodiment; FIG. 4 shows a schematic diagram of a table according to the invention with a height display device according to the invention in a fourth embodiment; FIG. 5 shows a schematic diagram of a table according to the invention with a height display device according to the invention in a fifth embodiment; FIG. 6 shows a schematic diagram of a table according to the invention with a height display device according to the invention in a sixth embodiment; FIG. 7 shows a schematic diagram of a table according to the invention with a height display device according to the invention in a seventh embodiment.Referring now to FIG. 1, there is shown a table 10 and a table stand 12 of the table 10 includes a pair of telescoping table legs 14. The table legs 14 can be supported on a floor 17 via foot booms 16. The table legs 14 support a table top 18, and the table top 18 can be fastened to plate supports, not shown in detail, of the table frame 12. The table legs 14 can be connected by means of a traverse, likewise not shown in detail. A blockable gas compression spring 20 is arranged in at least one of the table legs 14. During the adjustment of the height of the table top 18, the gas spring 20 carries at least part of the weight of the table top 18.A height display device 22 is attached to the table top 18. The height display device 22 has a sensor 24, here an ultrasonic sensor 24 a, in order to determine the height 26 of the table top 18. For this purpose, the sensor 24 is arranged on an underside 28 of the table top 18 and oriented vertically downwards towards the floor 17. A distance measurement value 30 may be added to the known distance 29 of the sensor 24 from a top 32 of the table top 18 to obtain the height 26.The height 26 is displayed on a display 34. The display 34 can be an e-paper display 34a which retains its display value for some time even when no more power supply is present.In order to provide the energy required for the operation of the height display device 22, an energy generator 36, here a solar module 36 a, is provided.Electrical energy produced by the energy generator 36 can be stored in an energy store 38, for example with an accumulator and / or a capacitor.A control device 40 coordinates the aforementioned components of the height display device 22, Here, the control device 40 is programmed to actuate the sensor 24 for a height measurement at certain time intervals, for example every 0.2 seconds, provided a minimum voltage is available. Furthermore, the control device 40 is programmed to only undertake a change in the height value displayed on the e-paper display 34 awhen the measured height has changed since the last update of the display. Both of the above-mentioned measures save energy and make possible a smaller dimensioning of energy generator 36 and energy store 38 or the use of a larger display 40 and / or a more precise sensor 24.In the embodiment of FIG. 1, all components of the height display device 22 are integrated into a common housing 42. The height display device 22 is thus formed by a single structural unit which can be mounted on the table top 18. For example, the housing 42 may be screwed, bonded, or clamped to the table top 18.FIG. 2 shows a modification of the height display device 22 from FIG. 1, the height display device 22 being let into a recess 44 on a longitudinal side 46 of the table top 18. The display 34 and the solar module 36 aterminate flush with the upper side 32 of the table top 18. It is understood that the recess with the height display device 22 could also be arranged within the surface of the table top (not shown in more detail).FIG. 3 shows a table 10 with a height display device 22, the energy generator 36 of which is arranged between two parts of one of the table legs 14 which are movable relative to one another during the height adjustment. Table legs 14 are shown in section in FIG. 3 to show the components received therein.The energy generator 36 is designed here as a linearly operating generator 36 b. A coil 48 is fixed to an upper segment 14a of the table leg 14. A permanent magnet 50 is fixed to a lower segment 14b of the table leg 14. In the event of a change in height, a voltage is thus induced in the coil 48, which serves to charge the energy store 38.The energy store 38 is arranged here, by way of example, at the coil 48. A housing 42 with the sensor 24, the display 34 and the control device 40 is mounted on the table top 18 separately from the energy generator 36 and the energy storage 38. It is understood that the energy storage device 38 could also be accommodated in the housing 42 (not shown in more detail).Incidentally, the table 10 and the height display device 22 may be configured as described above.FIG. 4 shows a table 10, the two table legs 14 of which are coupled by means of a synchronous shaft 52. In the upper segments 14a of the two table legs 14 there are mounted two respective rollers 54 over which a revolving means 56, for example a toothed belt or a chain, is guided. One end of a push rod 58 is fastened to the circulating means 56, the other end of which push rod is fixed to the lower segment 14 b. In this way, the two table legs 14 are forced to change their length synchronously with one another.The energy generator 36 is here a rotationally operating generator 36 b. A coil 48 of the generator 36 is secured to the table stand 12 or the table top 28. A permanent magnet 50 held on the synchronous shaft 52 rotates within the coil 48 during the height adjustment.In the embodiment of FIG. 4, the energy storage device 38 is arranged, for example, in the housing 42 with the sensor 24, the display 34 and the control device 40. The generator 36 bis mounted separately from the housing 42.Incidentally, the table 10 and the height display device 22 may be configured as described above.FIG. 5 shows a table 10, the lockable gas pressure spring 20 of which can be released for height adjustment by an operating element 60, here an operating lever. When the operating element 60 is actuated, a valve in the gas spring 20 is opened, here by way of example via a cable pull 62 and optionally a further mechanism on and / or in the gas spring 20, such that the table top 18 can be raised or lowered. When the operating lever 60 is released, the valve closes so that the set height is fixed.The energy generator 36 here has a piezoelectric element 36 c, which is compressed when the operating element 60 is actuated, so that an electrical voltage arises. In this way, electrical energy can be generated and stored in the energy store 38. The energy store 38 can be arranged in the housing 42 of the height display device 22 with its further components (illustrated here) or arranged on the operating element 60 at the energy generator 36 b(not illustrated in more detail).Incidentally, the table 10 and the height display device 22 may be configured as described above.FIG. 6 shows a table 10 with a height display device 22, which has an optical sensor 24 b, for example a laser distance sensor. It is understood that an optical sensor 24 bmay be provided in place of the ultrasonic sensor 24 ain the above-described height display devices 22. Conversely, an ultrasonic sensor 24a could also be provided in the embodiment of FIG. 6.A measuring direction of the sensor 24 can point vertically downwards (shown with a full double arrow).Alternatively, the measuring direction can be angled with respect to the vertical (shown with a dashed double arrow). The measuring direction can be inclined away from the table 10 in order to avoid incorrect measurements due to objects possibly located under the table 10.When the sensor 24 is disposed above one of the foot beams 16, the measurement direction may be directed toward a surface 64 of the foot beam 16. This may improve the reflection of the measurement signal back to the sensor 24 and may be particularly useful in optical sensors 24 b. In this case, the measurement direction can be oriented vertically (compare the solid double arrow) or can be inclined toward the foot boom 16 (not shown in more detail).It is understood that the inclination of the measuring direction and, if applicable, the distance 65 of the surface 64 of the foot extension 16 from the floor 17 are taken into account for the calculation of the height 26 to be displayed.If the foot extension 16 is less long or the sensor 24 is offset with respect to the foot extension 16 along the longitudinal edge 46, it is also possible to measure directly on the floor 17 in the case of a vertical measurement direction (compare in this respect FIGS. 1 and 3 to 5 ).In the embodiment of Fig. 6, a replaceable battery 66 is provided for power supply. Instead of the battery 66, one of the above-described energy generators 38 could also be provided.The display 34 can be an LED display 34 b, in particular an OLED display. The control device 40 can be programmed to display the new height 26 for a predetermined period of time, for example 10 to 30 seconds, after a change in height, and subsequently to switch off the display 34 b.An LED display 34 band corresponding programming could also be provided in the height display devices 22 described above.Conversely, in the height display device 22 of FIG. 6, an e-paper display 34 acan be provided here.Alternatively or additionally, a switching element 68, for example a button or a touch-sensitive field, can be provided, the current height 26 being displayed for a predefined period of time, for example 10 to 30 seconds, when said switching element is actuated. Alternatively or additionally, a height measurement can take place when the switching element 68 is actuated. The height measurement can take place continuously or at intervals of, for example, 0.2 seconds over a certain period of time, for example, 30 seconds to 2 minutes, the value displayed by the display 34 being updated continuously, for example every 0.5 seconds. In this way, the setting of a specific height 26 can be assisted. Such a switching element 68 and corresponding programming could also be provided in the above-described height display devices 22.FIG. 7 shows a table 10 with a height display device 22, the sensor 24 of which can be mounted separately from the display 34. The sensor 24, here an ultrasonic sensor 24 a, for example, is attached, for example adhesively bonded, to an underside 28 of the table top 18. The display 34, together with further components of the height display device 22, is arranged here on a furniture accessory 70, in the exemplary embodiment shown an acoustically and optically active panel. A cable 72 connects a housing 42 in which the display 34 is received to the sensor 24.The housing 42 also accommodates the energy generator 36 in the form of a solar module 36 a, the energy storage device 38 and the control device 40. It is understood that, for example, the control device 40 or the energy store 38 could be mounted together with the sensor 24. If instead of the solar module 36 a, a generator 36 bor a piezoelectric element 36 cis provided as the energy generator 36, these can be arranged as described above.The panel can be clamped to the table top 18 on a side facing away from the user. The panel may have trays for items that are not shown in detail. The housing 42 may be disposed on one of the shelves or attached to the bezel.In summary, the invention relates to a height display device for a table with a height-adjustable table frame. The table frame can have a gas pressure spring for supporting the height adjustment without electrical energy from a power network. The height display device is configured for autonomous operation without connection to a power grid. Preferably, an energy generator is provided in order to generate the energy for the operation of the height display device, in particular of its display and sensor. The energy generator can use movements taking place during the height adjustment for generating energy. Alternatively or additionally, the energy generator can have a solar module. The display is advantageously an e-paper display, which only requires electrical energy to update the display. The sensor is typically mountable to a table top to measure its height above the floor or a foot boom of the table frame.List of reference characters10 Table 12 Table frame 14 Table leg 14 a Oberes segment 14 b Unteres segment 16 Foot extension 17 Floor 18 Table top 20 Gas pressure spring 22 Height display device 24 Sensor 24 a Ultraschall sensor 24 b Optischer sensor 26 Height 28 Underside 29 Distance 30 Distance measurement value 32 Top 34 Display 34 aE paper display 34 b LED display 36 Energy generator 36 a Solarmodul module 36 bGenerator 36 c Piezoelement element 38 Energy store 40 Control device 42 Housing 44 Cutout 46 Longitudinal side 48 Coil 50 Permanent magnet 52 Synchronous shaft 54 Rollers 56 Circulatory means 58 Push rod 60 Operating element 62 Cable pull 64 Surface 65 Distance 66 Battery 68 Switching element 70 Furniture accessory 72 CableReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedWO 2019 / 086071 A2 [0002, 0003]

Claims

Height display device (22) for a height-adjustable table (10), comprising - a sensor (24) for measuring a height (26) of a table top (18); - a display (34) for displaying the height (26); - an energy generator (36) for generating electrical energy for operating the sensor (24) and the display (34).Height display device (22) according to Claim 1, furthermore having an energy store (38) for electrical energy generated by the energy generator (36), in particular a capacitor and / or an accumulator.Height display device (22) according to one of the preceding claims, wherein the energy generator (36) has a solar module (36a).Height display device (22) according to one of the preceding claims, further comprising an operating element (60), in particular for triggering a height adjustment of the table (10), wherein the energy generator (36) is attached to the operating element (60) in order to generate electrical energy upon actuation of the operating element (60).Height display device (22) according to one of the preceding claims, wherein the energy generator (36) has a piezoelectric element (36c).Height display device (22) according to one of the preceding claims, wherein the energy generator (36) has a generator (36b), in particular with a permanent magnet (50) which can be moved relative to a coil (48).Height display device (22) according to one of the preceding claims, further comprising a control device (40) for controlling the sensor (24) and the display (34), in particular wherein the control device (40) is configured to control the sensor (24) at predefined time intervals for height measurement when the energy supply is present and preferably to cause a change in the display of the display (34) only if the height (26) measured by the sensor (24) has changed.Height display device (22) according to one of Claims 1 to 7, wherein the sensor (24), the display (34), the energy generator (36) and, if appropriate, the control device (40) and the energy store (38) are combined in a single structural unit which can be mounted on a table top (18).Height display device (22) according to one of Claims 1 to 7, wherein the energy generator (36) can be mounted separately from the sensor (24) and / or the display (34) and / or the control device (40).Height display device (22) for a height adjustable table (10), comprising - a sensor (24) for measuring a height (26) of a table top (18); - a display (34) for displaying the measured height (26); - a replaceable battery (66) for providing electrical energy for operating the sensor (24) and the display (34).Height display device (22) according to one of claims 1 to 10, wherein the display (34) is configured to obtain its display value in a voltage-free state.The height display device (22) according to any one of claims 1 to 11, wherein the display (34) is an e-paper display (34a).Height display device (22) according to one of Claims 1 to 10, wherein the display (34) is an LED display (34b), in particular an OLED display.The height indicator (22) of any of claims 1 to 13, wherein the sensor (24) is an ultrasonic sensor (24a).Height display device (22) according to one of claims 1 to 13, wherein the sensor (24) is an optical sensor (24b), in particular a laser sensor, a lidar sensor or a time-of-flight sensor.Height-adjustable table (10) having a table top (18), having a table frame (12), preferably having at least one table leg (14) which can be varied in length, and having a height display device (22) according to one of the preceding claims.Table (10) according to claim 16, further comprising a preferably lockable gas spring (20) for assisting the height adjustment, preferably wherein the gas spring (20) is arranged in the table leg (14).Table (10) according to claim 16 or 17, wherein the display (34) is embedded in the table top (18) and / or is arranged on a longitudinal side (46) of the table top (18).Table (10) according to one of claims 16 to 18, wherein the display (34) can be arranged separately from the sensor (24).Table (10) according to one of claims 16 to 19, wherein the sensor (24) is arranged on an underside (28) of the table top (18).Table (10) according to one of Claims 16 to 20, wherein a structural unit of the height display device (22) comprising the display (34) and preferably the sensor (24) and optionally the control device (40) is screwed or glued to the table top (18) or is clamped firmly to the table top (18).The table (10) of any of claims 16 to 21, wherein the sensor (24) is directed toward a foot boom (16) of the table leg (14).Table (10) according to one of claims 16 to 22, wherein a measurement direction of the sensor (24) is angled with respect to the vertical, in particular away from the table top (18).Table (10) according to one of Claims 16 to 23, wherein the energy generator (36) of the height display device (22) designed according to one of Claims 1 to 8 is driven by an operating element (60) for releasing a fixing of a table frame (12), in particular for releasing a blocking of the gas pressure spring (20).Table (10) according to one of claims 16 to 24, wherein the energy generator (36) of the height display device (22) formed according to one of claims 1 to 8 is driven by a change in length of a telescopic table leg (14), in particular wherein the energy generator (36) is mounted between two parts of the table leg (14) which are movable relative to one another.Table (10) according to one of Claims 16 to 25, wherein a synchronous shaft (52) couples the changes in length of two table legs (14), and wherein the energy generator (36) of the height display device (22) configured according to one of Claims 1 to 8 is driven by the synchronous shaft (52).Table assembly, in particular for a table (10) according to one of claims 16 to 26, having a height-adjustable table frame (12), preferably having at least one table leg (14) which can be varied in length, and having a height display device (22) according to one of claims 1 to 15.

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