EP1233505A1 - Driving signal for electrodynamic vibration devices - Google Patents
Driving signal for electrodynamic vibration devices Download PDFInfo
- Publication number
- EP1233505A1 EP1233505A1 EP01104030A EP01104030A EP1233505A1 EP 1233505 A1 EP1233505 A1 EP 1233505A1 EP 01104030 A EP01104030 A EP 01104030A EP 01104030 A EP01104030 A EP 01104030A EP 1233505 A1 EP1233505 A1 EP 1233505A1
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- EP
- European Patent Office
- Prior art keywords
- signal
- driving
- driving signal
- electrodynamic
- vibration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/0207—Driving circuits
- B06B1/0223—Driving circuits for generating signals continuous in time
- B06B1/0269—Driving circuits for generating signals continuous in time for generating multiple frequencies
- B06B1/0284—Driving circuits for generating signals continuous in time for generating multiple frequencies with consecutive, i.e. sequential generation, e.g. with frequency sweep
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/04—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
- B06B1/045—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism using vibrating magnet, armature or coil system
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
- B06B2201/50—Application to a particular transducer type
- B06B2201/52—Electrodynamic transducer
- B06B2201/53—Electrodynamic transducer with vibrating magnet or coil
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
- B06B2201/70—Specific application
Definitions
- the present invention relates to a method for driving an electrodynamic or electromagnetic vibration device for outputting a vibration signal and a driving means for driving an electrodynamic or electromagnetic vibration device for outputting a vibration signal.
- Vibration signal or alert is a standard feature for mobile telecommunication means like mobile phones for GSM (Global System for Mobile Telecommunication) or UMTS (Universal Mobile Telecommunication System).
- GSM Global System for Mobile Telecommunication
- UMTS Universal Mobile Telecommunication System
- Known devices for generating vibration signals are often DC-motors with an excenter weight inside the mobile phone. The disadvantage of this solution is, that these motors are fairly expensive, they need space and they are heavy in weight.
- electrodynamic transducers which are driven with a sinewave current signal (further called sinewave signal) at their resonant frequency.
- sinewave signal a sinewave current signal
- the vibration function is combined in one signalling device with a speaker, ringer and/or receiver function.
- an electrodynamic vibration device for generating a vibration signal bases on an elastically suspended weight of a predetermined mass, which is brought to oscillation by an alternating magnetic field. Therefore, the electrodynamic vibration device comprises a coil for generating an alternating magnetic field caused by a sinewave signal, and the elastically suspended weight, which is normally a magnetic yoke with a predetermined weight and is brought to oscillation by the alternating magnetic field.
- the oscillation of the weight is transmitted through the elastic suspension (e.g. spiral springs) to the fixing of the weight and consequently to the case of the mobile telecommunication means.
- the output vibration strength is thereby maximal at the resonant frequency.
- the resonant frequency of those electrodynamic vibration devices is mostly between 100 and 200 Hz and is among other things determined by the elastic suspension (spring) and the weight.
- the bandwidth of the resonance frequency is rather small, around 10 Hz, and the resonant frequency of the mobile phone depends further on the mechanic load conditions like mass and the support of the mobile phone like suspension (strongly or loosely), clamping more or less tightly.
- the resonant frequency varies if the mobile telecommunication means is held in the hand, laid on a table, etc. Also, the resonant frequency depends on aging, temperature, tolerance of manufacturing, etc.
- the resonant frequency thus varies with different external conditions and so it is difficult to determine the exact resonant frequency of the mobile phone for these actual conditions for outputting a vibration signal with a predetermined strength at a predetermined frequency, whereby the predetermined output strength is optimally the maximum output strength at the resonant frequency.
- Figure 6 shows an example of the output vibration strength in dependence on the frequency f of the sinewave signal (solid line).
- the output vibration strength is maximal at the resonant frequency f res with a bandwidth ⁇ f 1 . It is seen, that the output vibration strength decreases rapidly, when the frequency of the sinewave signal differs from the resonant frequency ⁇ f res .
- the bandwidth ⁇ f of the resonant frequency f res can be broadened by lowering the quality of the resonant system; see also dotted line of figure 6 with the broadened bandwidth ⁇ f 2 .
- This can be achieved by enlarging the damping of the weight through the springs.
- the disadvantage of this solution is, that it is expensive, costly and the driving signal of the electrodynamic vibration device has to be more powerful to output the same strength of the vibration signal over the bandwidth. This reduces consequently the standby-time of the battery or accumulator powered mobile telecommunication means.
- a further solution is to sweep the frequency of the driving signal in the tolerance range of the resonant frequency, whereby a driving signal is generated, which contains signals with different ascending or descending frequencies at different times.
- the signal could be a sequence of sinewave signals with fixed frequencies in the tolerance range of the resonant frequency.
- Another possibility is to establish a feedback loop for the driving signal, using a sensor for the movement of the vibrating mass and thereby tuning the frequency of the driving signal automatically to the actual mechanic resonant frequency.
- This is a costly solution requiring also additional space.
- the above object is achieved by a method for driving an electrodynamic or electromagnetic vibration device for outputting a vibration signal with a predetermined vibration strength for a mobile telecommunication means according to claim 1.
- the above object is also achieved by a driving means for driving an electrodynamic or electromagnetic vibration device for outputting a vibration signal with a predetermined vibration strength for a mobile telecommunication means according to claim 8.
- the electrodynamic vibration device is driven by a driving signal, which comprises time successive alternating current signals of varying periods, whereby the variation of the periods is set so, that the perceived vibration strength is essentially constant for a user over time.
- a driving signal which comprises time successive alternating current signals of varying periods, whereby the variation of the periods is set so, that the perceived vibration strength is essentially constant for a user over time.
- the vibration strength is perceived constant for periodical changes of amplitude if the amplitude modulation frequency is higher than 20 Hz. That means that the maximum duration for a signal with constant period is 25 ms in the case that only two signals with different periods are output alternately. If more alternating current signals with different periods are output alternately, the mentioned duration of a signal with constant period will have to be accordingly shorter.
- the advantage of the present invention is, that the strength of the vibration signal is time-invariant and independent of the mechanic load conditions, so that the output vibration strength is varying barely noticeable for a user of the mobile telecommunication means. Further, the present invention is easily to implement in existing systems, since the driving signal according to the present invention can be generated digitally from a processor to get a digital signal with the predetermined periods. Then, the digital signal is converted to analog to get a sinewave signal for driving the electrodynamic vibration device. In another embodiment, the vibration device may also be driven digitally.
- the alternating current signals are sinewave signals of the same amplitudes.
- each signal contains n half periods, whereby n is equal to or larger than one.
- each signal contains one whole-numbered period. If the period of the sinewave signals is varied after one or a few whole-numbered periods, for example between one to three periods, the variation of periods is so fast, that a variation of the output vibration strength is essentially constant and consequently barely noticeable for the user of the mobile telecommunication means.
- the periods are dependent on the resonant frequency of the vibration device and varying in a narrow bandwidth in the range of the expected resonant frequency in order to output a maximum of vibration strength, whereby the resulting vibration strength is little below the maximum output vibration strength by driving the vibration device at exact the resonant frequency.
- the successive sinewave signals of the driving signal are concatenated at equal values in order to obtain a continuous function.
- the successive sinewave signals are concatenated at points of equal slope in order to obtain a differentiable function as a result. This avoids bounces and edges at the concatenations in order to avoid generating frequencies higher than the vibration frequency, i. e. audible frequencies.
- two sinewave signals of equal amplitude are concatenated, this is advantageously done at their common maximum value or minimum value respectively.
- both concatenated sinewave functions have the same value and a slope of zero, both above mentioned conditions are fulfilled this way.
- the resulting driving signal is differentiable in each part of it, likewise in order to avoid bounces at the transfer between signals of different periods and consequently to avoid generating frequencies above the vibration frequency.
- the driving signal according to the present invention generates minimum audible noise, i.e. it has low as possible components at frequencies higher than the vibration frequency, so that the present invention is advantageously used for combined signal outputting means, for example a vibration means combined with a loudspeaker for outputting a vibration signal as well as an alert tone.
- the resulting driving signal is amplitude modulated before it is output to the electrodynamic vibration device.
- This modulation can simply happen by switching on and off the driving signal, e.g. according to the timing of a call sign of an incoming call or according to the setting of the mobile telecommunication means by a user.
- the driving signal is switched on and/or off at a phase, where the unmodulated value of the driving signal is zero, i.e. at a phase which is zero, ⁇ or 2* ⁇ , again to avoid generating frequencies above the vibration frequency.
- Figure 1 shows an example of a signalling device 1 for outputting acoustic and vibration signals in a mobile telecommunication means, whereby the signalling device 1 is a combination of an electrodynamic vibration device and a speaker.
- the signalling device 1 is designed to output an acoustic signal like an alert tone as well as a vibration signal.
- This signalling device 1 is usually mounted inside on the backside of the case of the mobile telecommunication means.
- the signalling 1 device comprises a membrane 11 for outputting the acoustic signal, a weight 12, which represents the driven mass for the vibration device (and the mobile telecommunication means respectively) and is permanent magnetic, and a coil 13 for driving the membrane 11 and the weight 12.
- the weight 12 is connected by one or more elastic suspensions 14 (e.g. spiral springs) to a casing 15.
- the weight 12 with a predetermined mass and the elastic suspensions 14 in combination with the casing 15 builds the resonant system, which generates the vibration.
- the signalling device 1 is driven by a driving signal generated by the signal generating means 3 of the driving means 2, whereby the coil 13 is driven by an alternating current signal either in the range of the mechanical resonant frequency in order to output a vibration signal or in the range of an audible signal for outputting an alert tone.
- the driving means 2 For outputting an acoustic alert signal the driving means 2 generates a driving signal in kHz-range. This frequency, which is significantly higher than the described resonant frequency for outputting a vibration signal, causes the membrane 11 to oscillate and therefore to output an acoustic signal.
- the driving means 2 For outputting an vibration signal, the driving means 2 generates a driving signal according to the present invention.
- This signal contains frequencies, which are in the range of the (mechanical) resonant frequency of the mobile telecommunication means and causes the weight 12 to oscillate; this frequencies are mostly between 100 and 200 Hz with a predetermined bandwidth, for example with a bandwidth of around 10 Hz.
- Figure 2 shows a schematic diagram of the example of a resulting driving signal according to the present invention, by which the electrodynamic vibration device is driven.
- the periods are varying every whole-numbered period and are concatenated at the maximum amplitude; the time of the periods is given with t 1 , t 2 and t 3 .
- the periods can thereby vary time sequentially ascending or descending in period or vary arbitrary. According to the present invention it is more important, that the variation of periods happens fast, that means after one or a few periods, so that the output variation strength is essentially constant.
- Essentially constant means, that the output vibration signal is so low in variation over time, so that the user of the mobile phone barely notes a variation of the vibration strength over time caused by varying the periods during driving the electrodynamic vibration device.
- the electrodynamic vibration device is driven by a signal which consists of single or few sinewave periods with slightly changing frequency in the range of the bandwidth around the resonant frequency.
- a narrow band signal is generated which causes no noticeable change in vibration strength over time, in contrary to a sweep or longer periods with changing frequency.
- the segments are concatenated such that the resulting signal is continuous. Higher frequency products can be even further reduced if the resulting signal is also differentiable. This can be achieved best when the periods are concatenated either at maximum or minimum value.
- the present invention is for example implemented as software, whereby the driving signal for driving the signalling means 1 is generated digitally from a processor to get a digital signal with the predetermined periods. Then, the digital signal is converted to analog to get a sinewave signal for driving either the electrodynamic vibration device or the loudspeaker. In another embodiment, the vibration device or loudspeaker may also be driven digitally.
- Figure 3 to 5 shows different examples of the construction of an electrodynamic vibration device, which can be driven by a driving signal according to the present invention, whereby the driving means for generating this driving signal is not shown.
- Figure 3 to 5 shows examples of electrodynamic vibration devices with different constructions of the driven weight 12. Additional, this constructions contain at a time an iron core 16 of different constructions instead of a membrane, so that these devices are only designed for outputting a vibration signal.
- the iron core 16 amplifies the magnetic field generated by the coil 13, so that the output vibration strength is stronger than the output vibration strength by a combined signalling device according to fig. 1 at the same amplitude of the driving signal.
- the different constructions of the weights shown in fig. 2 and 3 causes likewise different vibration strengths of the electrodynamic vibration device at the same amplitude of the driving signal, whereby the construction shown in fig. 3 outputs a stronger vibration signal.
- the simple construction of the weight 12 is less costly than the construction of the weight 12 as shown in fig. 3.
- the elastic suspension 14 is designed as a leaf spring, at which the weight 12 is suspended. Further, the elastic suspension 14 comprises a permanent magnet 17.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Apparatuses For Generation Of Mechanical Vibrations (AREA)
- Details Of Audible-Bandwidth Transducers (AREA)
Abstract
The present invention relates to a method for driving an electrodynamic vibration
device for outputting a vibration signal with a predetermined vibration strength for a
mobile telecommunication means, whereby the electrodynamic vibration device is
driven by an alternating current driving signal. The driving signal comprises time
successive sinewave signals of varying periods, whereby the variation of the periods is
set so, that the duration of each alternating current signal with constant period is shorter
than 25 ms.
Further, the present invention relates to a driving means (2) for driving an
electrodynamic vibration device for outputting a vibration signal with a predetermined
vibration strength for a mobile telecommunication means for carrying out this method.
Description
The present invention relates to a method for driving an electrodynamic or
electromagnetic vibration device for outputting a vibration signal and a driving means
for driving an electrodynamic or electromagnetic vibration device for outputting a
vibration signal.
Vibration signal or alert is a standard feature for mobile telecommunication means like
mobile phones for GSM (Global System for Mobile Telecommunication) or UMTS
(Universal Mobile Telecommunication System). Known devices for generating vibration
signals are often DC-motors with an excenter weight inside the mobile phone. The
disadvantage of this solution is, that these motors are fairly expensive, they need space
and they are heavy in weight.
These are the reasons why these motors are more and more replaced by electrodynamic
transducers (further called electrodynamic vibration devices), which are driven with a
sinewave current signal (further called sinewave signal) at their resonant frequency.
Sometimes the vibration function is combined in one signalling device with a speaker,
ringer and/or receiver function.
The function of an electrodynamic vibration device for generating a vibration signal
bases on an elastically suspended weight of a predetermined mass, which is brought to
oscillation by an alternating magnetic field. Therefore, the electrodynamic vibration
device comprises a coil for generating an alternating magnetic field caused by a
sinewave signal, and the elastically suspended weight, which is normally a magnetic
yoke with a predetermined weight and is brought to oscillation by the alternating
magnetic field. The oscillation of the weight is transmitted through the elastic
suspension (e.g. spiral springs) to the fixing of the weight and consequently to the case
of the mobile telecommunication means. The output vibration strength is thereby
maximal at the resonant frequency.
The resonant frequency of those electrodynamic vibration devices is mostly between
100 and 200 Hz and is among other things determined by the elastic suspension (spring)
and the weight. The bandwidth of the resonance frequency is rather small, around 10
Hz, and the resonant frequency of the mobile phone depends further on the mechanic
load conditions like mass and the support of the mobile phone like suspension (strongly
or loosely), clamping more or less tightly. Further, the resonant frequency varies if the
mobile telecommunication means is held in the hand, laid on a table, etc. Also, the
resonant frequency depends on aging, temperature, tolerance of manufacturing, etc.
The resonant frequency thus varies with different external conditions and so it is
difficult to determine the exact resonant frequency of the mobile phone for these actual
conditions for outputting a vibration signal with a predetermined strength at a
predetermined frequency, whereby the predetermined output strength is optimally the
maximum output strength at the resonant frequency.
Figure 6 shows an example of the output vibration strength in dependence on the
frequency f of the sinewave signal (solid line). The output vibration strength is maximal
at the resonant frequency fres with a bandwidth Δf1. It is seen, that the output vibration
strength decreases rapidly, when the frequency of the sinewave signal differs from the
resonant frequency Δfres.
To solve this problem, the bandwidth Δf of the resonant frequency fres can be broadened
by lowering the quality of the resonant system; see also dotted line of figure 6 with the
broadened bandwidth Δf2. This can be achieved by enlarging the damping of the weight
through the springs. However, the disadvantage of this solution is, that it is expensive,
costly and the driving signal of the electrodynamic vibration device has to be more
powerful to output the same strength of the vibration signal over the bandwidth. This
reduces consequently the standby-time of the battery or accumulator powered mobile
telecommunication means.
A further solution is to sweep the frequency of the driving signal in the tolerance range
of the resonant frequency, whereby a driving signal is generated, which contains signals
with different ascending or descending frequencies at different times. Alternatively the
signal could be a sequence of sinewave signals with fixed frequencies in the tolerance
range of the resonant frequency. Both solutions have the disadvantage, that the strength
of the vibration signal appears to change over time depending on the vibration
transmission properties for the momentary frequency.
It is also possible to drive the electrodynamic vibration device with a noise signal with a
bandwidth covering the expected range of the resonant frequency. However, it is
difficult to generate a noise signal with constant noise power in the range of that
predetermined bandwidth. Alternatively a driving signal with different frequencies at
the same time (a so called multitone signal) could be provided to the electrodynamic
vibration device. Both signals have the disadvantage of a high crest factor and a
pronounced time structure, which could be perceived as changing vibration strength
over time.
Another possibility is to establish a feedback loop for the driving signal, using a sensor
for the movement of the vibrating mass and thereby tuning the frequency of the driving
signal automatically to the actual mechanic resonant frequency. However, this is a
costly solution requiring also additional space.
It is therefore the object of the present invention, to provide a method for driving an
electrodynamic vibration device for outputting a vibration signal for a mobile
telecommunication means and a driving means for driving an electrodynamic vibration
device, which output a vibration signal, which is time-invariant and independent of the
mechanic load conditions. Further, this signal should generate minimum audible noise,
i.e. it should have as low as possible components at frequencies higher than the
vibration frequency.
The above object is achieved by a method for driving an electrodynamic or
electromagnetic vibration device for outputting a vibration signal with a predetermined
vibration strength for a mobile telecommunication means according to claim 1. The
above object is also achieved by a driving means for driving an electrodynamic or
electromagnetic vibration device for outputting a vibration signal with a predetermined
vibration strength for a mobile telecommunication means according to claim 8.
According to the present invention, the electrodynamic vibration device is driven by a
driving signal, which comprises time successive alternating current signals of varying
periods, whereby the variation of the periods is set so, that the perceived vibration
strength is essentially constant for a user over time. Experiments show that the vibration
strength is perceived constant for periodical changes of amplitude if the amplitude
modulation frequency is higher than 20 Hz. That means that the maximum duration for
a signal with constant period is 25 ms in the case that only two signals with different
periods are output alternately. If more alternating current signals with different periods
are output alternately, the mentioned duration of a signal with constant period will have
to be accordingly shorter.
The advantage of the present invention is, that the strength of the vibration signal is
time-invariant and independent of the mechanic load conditions, so that the output
vibration strength is varying barely noticeable for a user of the mobile
telecommunication means. Further, the present invention is easily to implement in
existing systems, since the driving signal according to the present invention can be
generated digitally from a processor to get a digital signal with the predetermined
periods. Then, the digital signal is converted to analog to get a sinewave signal for
driving the electrodynamic vibration device. In another embodiment, the vibration
device may also be driven digitally.
In one embodiment of the present invention the alternating current signals are sinewave
signals of the same amplitudes.
In a further embodiment of the present invention, each signal contains n half periods,
whereby n is equal to or larger than one. Preferred, each signal contains one whole-numbered
period. If the period of the sinewave signals is varied after one or a few
whole-numbered periods, for example between one to three periods, the variation of
periods is so fast, that a variation of the output vibration strength is essentially constant
and consequently barely noticeable for the user of the mobile telecommunication means.
Further, the periods are dependent on the resonant frequency of the vibration device
and varying in a narrow bandwidth in the range of the expected resonant frequency in
order to output a maximum of vibration strength, whereby the resulting vibration
strength is little below the maximum output vibration strength by driving the vibration
device at exact the resonant frequency.
Advantageously, the successive sinewave signals of the driving signal are concatenated
at equal values in order to obtain a continuous function. Further advantageously the
successive sinewave signals are concatenated at points of equal slope in order to obtain
a differentiable function as a result. This avoids bounces and edges at the concatenations
in order to avoid generating frequencies higher than the vibration frequency, i. e.
audible frequencies. When two sinewave signals of equal amplitude are concatenated,
this is advantageously done at their common maximum value or minimum value
respectively. As both concatenated sinewave functions have the same value and a slope
of zero, both above mentioned conditions are fulfilled this way.
Further advantageously the resulting driving signal is differentiable in each part of it,
likewise in order to avoid bounces at the transfer between signals of different periods
and consequently to avoid generating frequencies above the vibration frequency.
This has the advantage, that the driving signal according to the present invention
generates minimum audible noise, i.e. it has low as possible components at frequencies
higher than the vibration frequency, so that the present invention is advantageously used
for combined signal outputting means, for example a vibration means combined with a
loudspeaker for outputting a vibration signal as well as an alert tone.
In a further embodiment of the present invention, the resulting driving signal is
amplitude modulated before it is output to the electrodynamic vibration device. This
modulation can simply happen by switching on and off the driving signal, e.g.
according to the timing of a call sign of an incoming call or according to the setting of
the mobile telecommunication means by a user. Advantageously, the driving signal is
switched on and/or off at a phase, where the unmodulated value of the driving signal is
zero, i.e. at a phase which is zero, π or 2*π, again to avoid generating frequencies
above the vibration frequency.
In the following description, preferred embodiments of the present invention are
explained in more detail in relation to the enclosed figures in which
Figure 1 shows an example of a signalling device 1 for outputting acoustic and vibration
signals in a mobile telecommunication means, whereby the signalling device 1 is a
combination of an electrodynamic vibration device and a speaker. Thus, the signalling
device 1 is designed to output an acoustic signal like an alert tone as well as a vibration
signal. This signalling device 1 is usually mounted inside on the backside of the case of
the mobile telecommunication means.
The signalling 1 device comprises a membrane 11 for outputting the acoustic signal, a
weight 12, which represents the driven mass for the vibration device (and the mobile
telecommunication means respectively) and is permanent magnetic, and a coil 13 for
driving the membrane 11 and the weight 12. The weight 12 is connected by one or
more elastic suspensions 14 (e.g. spiral springs) to a casing 15. The weight 12 with a
predetermined mass and the elastic suspensions 14 in combination with the casing 15
builds the resonant system, which generates the vibration.
The signalling device 1 is driven by a driving signal generated by the signal generating
means 3 of the driving means 2, whereby the coil 13 is driven by an alternating current
signal either in the range of the mechanical resonant frequency in order to output a
vibration signal or in the range of an audible signal for outputting an alert tone.
For outputting an acoustic alert signal the driving means 2 generates a driving signal in
kHz-range. This frequency, which is significantly higher than the described resonant
frequency for outputting a vibration signal, causes the membrane 11 to oscillate and
therefore to output an acoustic signal.
For outputting an vibration signal, the driving means 2 generates a driving signal
according to the present invention. This signal contains frequencies, which are in the
range of the (mechanical) resonant frequency of the mobile telecommunication means
and causes the weight 12 to oscillate; this frequencies are mostly between 100 and 200
Hz with a predetermined bandwidth, for example with a bandwidth of around 10 Hz.
Figure 2 shows a schematic diagram of the example of a resulting driving signal
according to the present invention, by which the electrodynamic vibration device is
driven.
In this example the periods are varying every whole-numbered period and are
concatenated at the maximum amplitude; the time of the periods is given with t1, t2 and
t3. The periods can thereby vary time sequentially ascending or descending in period or
vary arbitrary. According to the present invention it is more important, that the
variation of periods happens fast, that means after one or a few periods, so that the
output variation strength is essentially constant.
Essentially constant means, that the output vibration signal is so low in variation over
time, so that the user of the mobile phone barely notes a variation of the vibration
strength over time caused by varying the periods during driving the electrodynamic
vibration device.
According to the present invention, the electrodynamic vibration device is driven by a
signal which consists of single or few sinewave periods with slightly changing
frequency in the range of the bandwidth around the resonant frequency. By doing this, a
narrow band signal is generated which causes no noticeable change in vibration strength
over time, in contrary to a sweep or longer periods with changing frequency. In order
to limit the spectrum of the generated signal to the desired narrow frequency band, the
segments are concatenated such that the resulting signal is continuous. Higher frequency
products can be even further reduced if the resulting signal is also differentiable. This
can be achieved best when the periods are concatenated either at maximum or minimum
value.
In Figure 6 is shown, that the resulting vibration strength, caused by the inertia of the
weight, is little below the maximum output vibration strength by the driving the
vibration device at exact the resonant frequency fres.
The present invention is for example implemented as software, whereby the driving
signal for driving the signalling means 1 is generated digitally from a processor to get a
digital signal with the predetermined periods. Then, the digital signal is converted to
analog to get a sinewave signal for driving either the electrodynamic vibration device or
the loudspeaker. In another embodiment, the vibration device or loudspeaker may also
be driven digitally.
Figure 3 to 5 shows different examples of the construction of an electrodynamic
vibration device, which can be driven by a driving signal according to the present
invention, whereby the driving means for generating this driving signal is not shown.
Figure 3 to 5 shows examples of electrodynamic vibration devices with different
constructions of the driven weight 12. Additional, this constructions contain at a time
an iron core 16 of different constructions instead of a membrane, so that these devices
are only designed for outputting a vibration signal. The iron core 16, however,
amplifies the magnetic field generated by the coil 13, so that the output vibration
strength is stronger than the output vibration strength by a combined signalling device
according to fig. 1 at the same amplitude of the driving signal.
The different constructions of the weights shown in fig. 2 and 3 causes likewise
different vibration strengths of the electrodynamic vibration device at the same
amplitude of the driving signal, whereby the construction shown in fig. 3 outputs a
stronger vibration signal. However, the simple construction of the weight 12 is less
costly than the construction of the weight 12 as shown in fig. 3.
In Figure 5 the elastic suspension 14 is designed as a leaf spring, at which the weight 12
is suspended. Further, the elastic suspension 14 comprises a permanent magnet 17.
Thus, a electromagnetic field caused by the coil 13 and the iron core 16 lead to
oscillation of the weight 12.
It is noted, that the present invention on the basis of an electrodynamic vibration device
as described above could also be used for electromagnetic vibration devices, which
bases on the electromagnetic transduction principle.
Claims (20)
- Method for driving an electrodynamic or electromagnetic vibration device for outputting a vibration signal with a predetermined vibration strength for a mobile telecommunication means, whereby the electrodynamic or electromagnetic vibration device is driven by an alternating current driving signal, the driving signal comprising time successive alternating current signals of varying periods (t1...t3), whereby the variation of the periods is set so, that the duration of each alternating current signal with constant period t1 is shorter than 25 ms.
- Method according to claim 1,
characterized in that the alternating current signals are sinewave signals. - Method according to claim 1 or 2,
characterized in that the alternating current signals feature equal amplitudes. - Method according to claim 1, 2 or 3,
characterized in that the periods (t1...t3) are varying in a narrow bandwidth in the range of the resonant frequency. - Method according to one of the claims 1 to 4,
characterized in that the successive sinewave signals of the driving signal are concatenated at equal value. - Method according to one of the claims 1 to 5,
characterized in that the successive sinewave signals of the driving signal are concatenated at equal slope. - Method according to one of the claims 1 to 6,
characterized in that the successive sinewave signals of the driving signal are concatenated at minimum or maximum value. - Method according to one of the claims 1 to 7,
characterized in that the resulting driving signal is amplitude modulated before it is output to the electrodynamic or electromagnetic vibration device. - Method according to claim 8,
characterized in that the resulting driving signal is modulated by switching on and off. - Method according to claim 9,
characterized in that the driving signal is switched on and/or off at a phase, where the unmodulated value of the driving signal is zero. - Driving means (2) for driving an electrodynamic or electromagnetic vibration device for outputting a vibration signal with a predetermined vibration strength for a mobile telecommunication means, whereby the electrodynamic or electromagnetic vibration device is driven by an alternating current driving signal, comprising
a signal generating means (3) for generating a driving signal comprising time successive alternating current signals of varying periods (t1...t3), whereby the variation of the periods (t1...t3) is set so, that the duration of each alternating current signal with constant period (t1) is shorter than 25 ms. - Driving means (2) according to claim 11,
characterized in that the alternating current signals output by the signal generating means (3) are sinewave signals . - Driving means (2) according to claim 11 or 12,
characterized in that the alternating current signals output by the signal generating means (3) feature equal amplitudes. - Driving means (2) according to claim 11, 12 or 13,
characterized in that the signal generating means (3) generates sinewave signals, the periods (t1...t3) of which are varying in a narrow bandwidth in the range of the resonant frequency. - Driving means (2) according to one of the claims 11 to 14,
characterized in that the signal generating means (3) concatenates the successive sinewave signals of the driving signal at equal value. - Driving means (2) according to one of the claims 11 to 15,
characterized in that the signal generating means (3) concatenates the successive sinewave signals of the driving signal at equal slope. - Driving means (2) according to one of the claims 11 to 16,
characterized in that the signal generating means (3) concatenates the successive sinewave signals of the driving signal either at maximum or at minimum value. - Driving means (2) according to one of the claims 11 to 17,
characterized in that the signal generating means (3) modulates the resulting driving signal in amplitude before the driving signal is output to the electrodynamic or electromagnetic vibration device. - Driving means (2) according to claim 18,
characterized in that the signal generating means (3) modulates the resulting driving signal by switching on and off. - Driving means (2) according to claim 19,
characterized in that the signal generating means (3) switches the driving signal on and/or off at a phase, where the unmodulated value of the driving signal is zero.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP01104030A EP1233505A1 (en) | 2001-02-20 | 2001-02-20 | Driving signal for electrodynamic vibration devices |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP01104030A EP1233505A1 (en) | 2001-02-20 | 2001-02-20 | Driving signal for electrodynamic vibration devices |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP1233505A1 true EP1233505A1 (en) | 2002-08-21 |
Family
ID=8176538
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP01104030A Withdrawn EP1233505A1 (en) | 2001-02-20 | 2001-02-20 | Driving signal for electrodynamic vibration devices |
Country Status (1)
| Country | Link |
|---|---|
| EP (1) | EP1233505A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019097229A (en) * | 2017-11-17 | 2019-06-20 | ミツミ電機株式会社 | Vibration actuator and portable device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1991020136A1 (en) * | 1990-06-18 | 1991-12-26 | Motorola, Inc. | Selective call receiver having a variable frequency vibrator |
| US5436622A (en) * | 1993-07-06 | 1995-07-25 | Motorola, Inc. | Variable frequency vibratory alert method and structure |
| EP0952663A2 (en) * | 1998-04-23 | 1999-10-27 | Matsushita Electric Works, Ltd. | Driving circuit for oscillatory actuator |
| EP1008394A1 (en) * | 1998-06-29 | 2000-06-14 | Matsushita Electric Industrial Co., Ltd. | Electrical/mechanical/sound converter and apparatus of electrical/mechanical/sound conversion |
-
2001
- 2001-02-20 EP EP01104030A patent/EP1233505A1/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1991020136A1 (en) * | 1990-06-18 | 1991-12-26 | Motorola, Inc. | Selective call receiver having a variable frequency vibrator |
| US5436622A (en) * | 1993-07-06 | 1995-07-25 | Motorola, Inc. | Variable frequency vibratory alert method and structure |
| EP0952663A2 (en) * | 1998-04-23 | 1999-10-27 | Matsushita Electric Works, Ltd. | Driving circuit for oscillatory actuator |
| EP1008394A1 (en) * | 1998-06-29 | 2000-06-14 | Matsushita Electric Industrial Co., Ltd. | Electrical/mechanical/sound converter and apparatus of electrical/mechanical/sound conversion |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019097229A (en) * | 2017-11-17 | 2019-06-20 | ミツミ電機株式会社 | Vibration actuator and portable device |
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