Toothbrush

An electrically operated toothbrush comprises a housing with an electromotor inside the housing. The motor includes a rotatable shaft, means converting the rotary movement of the rotary shaft to an oscillatory movement of a brush support shaft which extends through the housing, and a toothbrush is attached to the free end of the support shaft outside of the housing. Sensing structure generates an impulse representative of the pressure exerted on the toothbrush during toothbrushing. A microprocessor or electronic device receives the impulses from the sensing structure during toothbrushing and compares those impulses with stored information representative of a predetermined optimum pressure range for toothbrushing. A signal transmittor releases a signal perceptible by the user of the toothbrush when the pressure on the toothbrush exceeds the predetermined optimum pressure range.

The present invention relates to a toothbrush, particularly an electrically 
operated toothbrush, which allows the user to determine and observe the 
correct pressure when cleaning the teeth. 
An essential criterion of the optimum function of a toothbrush, 
particularly an electric toothbrush, is the maintenance of a correct 
pressure when using the toothbrush. If the pressure is too low there is no 
sufficient cleaning. If the pressure is too high the gums are irritated 
resulting in bleeding of the gums and, as a long-term effect, probably 
even in a retrogression of the gingiva and exposure of the dentin. Thus, 
an essential condition for optimum toothbrushing, especially when using an 
electrically operated toothbrush, consists in cleaning with a correct 
pressure. 
The present invention thus starts out from the problem to construct a 
toothbrush which allows the user to adjust the adequate pressure when 
using the brush and to maintain this pressure during toothbrushing. 
The solution of this problem consists in providing a toothbrush, preferably 
an electrically operated toothbrush, whose construction is known per se, 
being fitted with an equipment for the optical or acoustical indication 
informing the user when leaving the optimum pressure during toothbrushing. 
If an electrically operated toothbrush is used the construction is realized 
in the following way: A pressure sensor is fixed at the axle bearing 
provided for the incorporation of the brush shank which records the 
pressure effective at the slip-on brush and which is connected to a 
microprocessor, in which the optimum pressure range is recorded which is 
compared with the actual pressure value effective at the brush. The 
microprocessor is connected to a signal transmitter in such a way that in 
case of exceeding or remaining under the recorded optimum pressure range a 
perceptible signal is released. 
In the case of a manual toothbrush the pressure is measured by strain 
gauges which are also connected to a microprocessor. In this case it is 
possible and also suitable to design the equipment for pressure 
measurement and signal release in such a way that it can be used for a 
great number of manual toothbrushes, i.e., it can be removed from the old 
brush and further used when the toothbrush is exchanged. 
From German Pat. No. 3,117,160 an electrically operated toothbrush is 
already known which is supposed to allow the user a control of the 
brushing time. This is realized by the fact that this toothbrush is 
provided with a timer which controls the brushing time and which starts 
operating when the toothbrush is switched on, and with an indicator 
element; the timer, controlled by a load measurement equipment, should 
only work during that operating time in which a set strain is exerted on 
the bristle part and at the end of a set minimum operating time the timer 
releases a signal. 
Thus, this known toothbrush has nothing in common with the problem of and 
its solution by the present invention, i.e., to allow the observation of 
the optimum pressure during the use of the toothbrush and to indicate 
upward and downward deviations from a recorded optimum pressure range by 
means of a signal transmitter.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 an electrically operated toothbrush designed according to the 
invention is shown: 
In a casing (1) there are housed an electromotor (2), an accumulator or a 
battery (3), a gear (4) for the conversion of the rotary movement of the 
motor into an oscillatory movement of the brush support shaft (5) and the 
slip-on brush (11), a switch (6) and the axle bearing (7). 
A pressure sensor (8) at the bearing (7) records the effective pressure at 
the slip-on brush (11) and transmits it to a microprocessor (9). 
In the microprocessor (9) an optimum pressure range is recorded which is 
compared with the actual pressure value effective at the brush. If both 
values are identical there is no reaction. 
If the pressure at the slip-on brush (11) is higher or lower than the 
recorded optimum range, the microprocessor (9) releases an optical or 
acoustical signal, perceptible by the user, via a signal transmitter (10) 
which causes the user to change the pressure of the toothbrush against the 
teeth until the signal disappears. 
Of course, it is also possible to adjust the equipment in such a way that 
the signal is kept on during the recorded optimum toothbrushing pressure 
and switches off when that pressure range is left. 
FIG. 2 shows the schematic construction of the above described loop 
control. 
A further preferable embodiment of the invention is the measurement of the 
toothbrush pressure via the current consumption of the electromotor of the 
brush. 
This method is based on the observation that a direct correlation exists 
between the pressure exerted during the use of the toothbrush and the 
current consumption of its electromotor: The higher the pressure, the 
higher the consumption and vice versa. 
So by defining certain consumption ranges in relation to the desired 
pressure, undesired deviations may be indicated to the user by a signal 
transmitter. 
FIG. 3 illustrates the above described embodiment of the invention wherein 
many of the components are similar to the components of the toothbrush 
shown in FIG. 1. Such similar components are identified by similar 
reference characters. In the embodiment of FIG. 3, current consumption of 
the electromotor is determined by electronic device 9 via a connecting 
line between such device and the electrical supply to the motor 2. When 
the current consumption of the electromotor exceeds a predetermined 
amount, the electronic device energizes the signal transmittor 10 which 
releases an optical or an acoustical signal perceptible by the user of the 
toothbrush.