Horizontally supported planar surfaces – Power driven
Patent
1985-11-18
1987-12-22
Aschenbrenner, Peter A.
Horizontally supported planar surfaces
Power driven
34087038, 108147, A47B 8500
Patent
active
047140259
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an arrangement for a switchboard desk with a height adjustable desk top. The height adjustable desk top is equipped with two or more telescopic legs. The arrangement comprises a device which effects the raising and lowering of the desk top and devices to control the effective devices.
It is already known to make desks with a desk-top and a leg framework such that the desk-top can be raised and lowered in conjunction with manual influencing devices. It is also known to provide electric motors in the respective telescopic legs of a desk which can be raised and lowered, to effect the raising and lowering of the desk-top. The electric motors are controlled by electrical circuits. Code plate devices are provided on the telescopic legs for monitoring the actual position of the desk-top and in addition indicating devices are provided to enable the desk-top height to be read off from the upper side.
DESCRIPTION OF THE INVENTION
THE TECHNICAL PROBLEM
There is an overall aim with this kind of desk to obtain a technically simple and yet satisfactorily functioning design for the various parts of the desk. One requirement in this connection is for a minimum of components in the control and effective devices. To provide, for example, electric motors on at least two of the telescopic legs of the desk complicates the construction and is relatively expensive at the same time.
SUMMARY OF THE INVENTION
The main object of the present invention is to propose an arrangement which solves the above-mentioned problems. It can be considered essentially characteristic of the new arrangement that the effective devices comprise at least two hydraulic cylinders each positioned in its respective telescopic leg and connected to at least one hydraulic pump which can be driven by an electric motor. It is a further characteristic of the the present invention that the controlling devices comprise manually actuated devices which switch on the electric motor to rotate in either direction according to the way they are actuated, and that a device monitoring the rotation of the electric motor actuates indicating devices which show the position of the desk-top above a reference level which may be formed by the floor on which the desk is set up.
Further embodiments of the present invention relate to more detailed information on how the various parts of the apparatus. Thus, in a preferred embodiment the devices monitoring the rotation of the electric motor consist of potentiometer devices which supply voltage to a digital volt-meter, the outputs of which are connected or may be connected to the indicating devices. The potentiometer devices here can comprise at least one potentiometer which is incorporated in a voltage divider, the central outlet of the potentiometer being connected for voltage supply to the digital voltmeter.
The electric motor is controlled by means of the manual influencing devices which control according to their actuation the voltage supply to relay devices or corresponding devices. The relay devices or corresponding devices connect power supply to the electric motor.
In the first embodiment of the invention a first relay is employed for actuating the motor in a first direction of rotation, which may correspond to a downward movement of the desk-top. In a corresponding manner, a second relay connects the current to actuate the electric motor in a second direction of rotation, which thus corresponds to upward movement of the desk-top.
The apparatus is provided with limits switches for obtaining a maximum and minimum position of the desk-top above the reference level, which means that the desk top may be operated only over a predetermined distance.
In a preferred embodiment of the invention the devices which monitor the rotation of the electric motor are designed so that a variation brought about by one of these devices of approximately 1 mV in a supply voltage output corresponds to a raising or lowering of the desk-top by approximately 1.0 mm. The potentiometer may also b
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Johansson Lars A.
Lundstrom Kurt A.
Svensson Ake P.
Wallin Per Olov T.
Warell Bengt H.
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