Note: Descriptions are shown in the official language in which they were submitted.
~ 0 9~/'65~; PCT/I~S93/0;9 1 1
- 2 1 3 ~ 3 4 3
LTI-801JND ~E~ICI,E ~IORN 8YgTE~
TEC~NICA~ FIELD
This invention relates in general to the use
of sounds to convey information to a vehicle
operator and to persons outside the vehicle. In
particular, the invention relates to a vehicle horn
system that uses the vehicle horn or horns not only
ls as an audible warning to others, but also to alert
the driver or others of the occurrence of an event,
such as a change in the status of a vehicle alarm or
that the vehicle is backing up. The invention also
relates to a horn system that, upon activation of
the horn switchj produces one of a pair of sounds
depending upon vehicle speed.
` ~ACl~t~ROlJ11D OF T9~1~ SN~ION `
The use of sound generating devices on
vehicles to produce sounds that convey information
to persons within and without the vehicle is well - -~
stab}ished. Devices employed to convey information
to persons outside the vehicle include vehicle horns ~-
~ and, more recently, sound transducers used in `;
vehicle alarm systems. Devices employed to convey l`-
, I information to occupants of the vehicle include
buzzers or other sound transducers which indicate
that, for example, a door is ajar, seat belts should i i`
~ ~ 30 be fastened, or the headlights have b-en l-ft on.
: ~ . . ., ;: :,.
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W0 941'655; 213~ 3 4 3 PCT/USg3loSg~
- 2 ~
For many years, the electric horns commonly
used on automotive vehicles have been of the type
which generate sound by vibration of a diaphragm
driven by an electromagnet motor. The horn
typically comprises a housing with the diaphragm
peripherally clamped thereto forming a motor
chamber. The coil of the electromagnet is mounted
within the chamber and a magnetic pole piece on the
housi~g extends axially of the coil. A magnetic
plunger on the diaphragm extends toward the pole
piece for imparting ~otion to the diaphragm in
response to periodic energization of the coil. The
diaphragm provides a rasilient suspension of the
plunger for reciprocating motion relative to the
coil; it has a spring characteristic whareby the
diaphrag~ and the mass carrisd by it`have a resonant
frequency of mechanical vibration. The coil is
energized ~rom the vehicle battery through a
- ` mechanically actuated switch which is alternately
opened and closed by movement of the plunger with
the di~phragm. ~ vehicle horn of this kind is
sometimas referred to as a mechanically-switched
type horn.~ A specific example of this typa of horn
is described in U.S. Patent No. 4t813,123, granted
- 25 ~arch 21, 1989 to Wilson et al., the disclosure of
which is hereby incorporated by reference.
More recently, vehicle horns that employ a
solid state driver circuit for the horn coil have
been developed. Sea, for example, U.S. Patent No.
5,04~,853, granted September 17, 1991 to Yoon, the
disclosure of which is hereby incorporated by
: . ~
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09~/26i~; 213~3 4 3 pcTl~lss3los9
reference. That patent discloses a vehicle horn
that uses a solid state driver circuit instead of a
mechanical switch to provide the necessary pulses of
driving current to the horn coil. The driver
circuit is adapted to energize the horn coil to
cause vibrations of the diaphragm at its resonant
frequency. The solid state driver has an electronic
timer adjustable to the frequency of the diaphragm
assembly and switches a solid state power output
stage to drive the diaphragm synchronously with the
timer frequency. A driver output st,age comprises a
power MOSFET or a Darlington pair. This type of
horn is sometimes referred to as an electronically-
switched type horn. Another type of electronically-
switched type horn, sometimes referred to as a
"three-wire" horn, is disclosed in U.S.S.N. 684,693,
filed April 12, l991 in the name of Wilson et al.
and assigned to the assignee of the present
invention.
Regardless of the type or frequency of the
hoxn, vehicl,e horn syst,~ms are generally designed
for a singular purpose - to create a sound that
alerts persons nearby of the presence of the
vehicle. It has been found that a horn which
qenerates a plurality of freqùencies provides a
sound that has a pleasing effect and yet is
effective for its intended purpose. Multiple
frequency sound generation has been accomplished in
` 30 many ways. For example, U.S. Paten~ No. 2,glOr~88,
granted October 27, 1959 to Kelley et al., disclos~s
a circuit arrangement which includes two oscillators
....
, ~
..., ~ ~:
.-, ,-.,
--~ U'O 94/265i~ 213~ 3 ~ 3 PCTll,'S93/0;911
- 4 -
that operata at different frequencies and that drive ;
a loudspeaker to generate a sound having two
frequency components. See also, U.S. Patent No. ~`
2,910,689, granted October 27, 1959 to Grace. ~-
~ ~-
Another way to generate a sound composed of
a plurality of fraquencies is disclosed in U.S. -~
Patent No. 4,486,742, granted December 4, 1984 to
- . i:
Kudo et al. In that patent, an oscillator circuit
. ,.~
is used to operate a piezoelectric vibrator at one
of its two (or more) resonant frequencies. The
oscillator output is amplitude ~odulated at a
frequency equal to the frequency separation between
the two resonant frequencies of the piezoelectric.
` Yet another way to genera~e a multiple
frequency sound is to use a pair of either the
electronically-switched or mechanically-switched
type horns described above. To produce a desirable
sound, one o~ tha horns is designed for relatively
low frequency operation ~nd the other for relatively
high frequèncy operation. For example, one horn may
be ~designed to have a reæonant ~requency of four
hundred hertz and the other dasigned to have a
resonànt fraquency of five hundred her~z.
In all of these arrangements, the various
frequencies are generated simultaneously to produce
a single horn sound. In the ~elley et al., Grace,
and Kudo patents mentioned above, a single
` transducer (i.e., loudspeaker or piez~electric) is
energized by a waveform that produces a single sound
` ~,-
~os~l2ssss PcTluss3los9ll
~- 2~ 3q~3
5 .
composed of a plurality of frequencies. In the two-
horn system described above, the two horns are
operated simultaneously by activation of the vehicle
horn switch such that their aural output is
perceived as a single sound.
In applications other than vehicle horn
systems, circuits have been disclosed that allow
selection of one of a plurality of sounds. Such
circuits have been proposed for applications
involving the generation of siren sounds as used,
for example, in emergency vehicles. U.S. Patent No.
3,493,966, granted February 3, 1970 to Human,
discloses an audible al`arm device having a pair of
oscillators and a switch that permits selection of
either a horn or a siren sound. U.S. Patent No.
--
3,873,980, granted March 25, 1975 to Carroll, and
U.S. Patent No. 4,040,Q50, granted August 2, lg77 to
Nunn, Jr., disclo~e circuits for emergency vehicles
that permit switching between "wail" and "yelp"
iren sounds. Nona of these patents, however,
~ disclose or sugg2st utilizing a standard vehicle
;~ horn for producing tho~s sounds in addition to the
usual horn warning sound that is produced upon
~- 25 activation of the vehicle horn switch. The patent
to Nunn, 3r. expressly provides a separate siren for
producing the "wail" and "yelp" sounds. Moreover,
none of these patents teach or suggest how the
circuitry disclosed therein could be incorporated
into a vehicle horn system.
,,,,.~.
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i ~W0 94/265;; ~ ~L 3~ 3 4 ~ PCTIUS93/05911
'; . ~:
- 6
- ~.: ;"'
Circuits have also been disclosed that
provide a vehicle operator with audible signals in
accordance with certain operating conditions of the
vehicle. U.S. PAtent No. 4,785,280, granted
November 15, 1988 to Fubini et al., discloses a
microprocessor controlled system that uses a
loudspeaker to produce audible signals which provide
the operator with information concerning various
vehicle operating conditions, such as fuel level,
oil temperature, oil pressure, and tire pressure. ;~;
Each different operating condition has a different
sound associated with it so that the operator can ~`
determine which of the various operating conditions
being monitored naeds attention. Similarly, U.S. `~
Patent No. 4,421,052, granted December 20, 1983 to
Cook, discloses a tire pressure signalling device
- t~at generates an acoustic signal when the ~ire
` pressure falls below a predetermined Ievel. The
acoustic signal is datected by a microphone and used
to warn the operator via a dashboard light or
buzzer. Neither of these two patents disclose or
suggest using the vehicle horn to alert the operator
of the monitored vehicle condition that needs
attention. Rather, they both te~ch using a separate
~sound-tran ducer~(i.e., a loudspeaker or buzzer).
Similar arrangements have been used in fields
even more remote from vehicle horn systems. For
example, U.S. Patent No~ 4,224,613, granted -
September 23, 1980 to Kaiser et al., discloses a
warning system for a printing press that uses one or ~;~
more speakers to produce any of a plurality of
:~
~VO 9-1/2655; PCTIUS93/059 1 1
~ 2~3~343
sounds, each of which is associated with a different
operating condition of the printing press.
Also known in the prior art are various
electrical and mechanical arrangements for varying
the sound output of the vehicle horn in accordance
with vehicle speed. The above-mentioned patent to
Grace ~iscloses a circuit that includes a speed
control circuit which adjusts the volume of the
sound produced by a loudspeaker as a function of
vehicle speed. The patent to Fubini et al. disclose
a similar system that operates under con~rol of a
microprocessor. Mechanical arrangements using mutes
for lowering the volume of a vehicle horn at lower
speeds are disclosed in U.S. Patent No. 2~301,344,
granted November 10, 1942 to Ti~ettsj and U.S.
Patent No. 2,694,806, granted November 16, 1954 to
Johnson.
8~X~ARY OF T~ I~YENTlO~
In accordance with the present invention,
there is provided a vehicle horn system that is
operable to produce any of~a plurality of sounds via
the vehicle horn. The horn system includes a
vehicle horn, a horn switch couplèd to the vehicle
horn, and a control circuit oupled to the vehicle
horn and having a plurality of inputs for providing
the circuit with a plurality of input signals. The
~` 30 control circuit is operable to control the sound
produced by the vehicle horn in accordance with the
input signals and the horn switch is coupled to a
; ~ ' '~" ',
,' :"`,'
/O 9~1265;; 21 3Y3 4 3 PCT/l,'S93/05911 ~ ;
first one of the plurality of inputs to thereby
provide the control circuit with a first one of the
plurality of input signals upon the horn switch
being activated. Thus, when the horn switch is
activated, the control circuit operates the horn to
produce a first sound, which preferably is a
continuous horn sound at the horn's resonant
; frequency. The other inputs of the control circuit
can be connected to various vehicle electrical
devices, such as a reverse or back-up switch and an
alarm system. The horn utilized can either be a
mechanically-switched type horn ox an
electronically-switched type horn. `~
Preferably, the control circuit is configured
to resolve conflicts between inputs occurring
simultaneously. In doing so, activation of t~e horn
switch is given top priority and the control circuit
therefore produces the normal full horn sound upon
activation of the horn switch, even if the control --
~ circuit is currently serving another input. ~ ~`
`~ In another aspect of the invention, the horn
system includes a second horn having a resonant
frequency that is different than the resonan~
frequency of the first horn and the control circuit
~, is operable to control the sound produced by the ~ -
second vehicle horn in accordance with the inpu~ -
signals. The outputs of the two horns can be -~
combined in various ways to produce different sounds
that are associated with different events. -~
:~
:~
wos~/26;~; pcT~tss3lo;9ll
r 213ql3~3
In yet another aspect of the invention, the . ~.
first and second vehicle horns can be used as part
of a speed-responsive vehicle horn system. This can . .~`
be accomplished using a vehicle speed sensor
5connected to the control circuit with the control ~- .
circuit being configured to operate one or both of ~ -
the vehicle horns depending upon the measured ~.. ~.. -.:
vehicle speed. Pre~erably, the control circuit is ........ `.
configured to operate both o~ the vehicle horns when
~ 10the horn switch is activated and the vehicle speed
is greater than a preset speed, and the control ~ `;
circuit is configured to operate only one of the ~.
vehicle horns when the horn switch is acti~ated and ``.`
the vehicle speed is 1QSS than or egual to the ..
15preset speed~ Preferably, only the horn having the .~.``;
lower resonant frequency is operated when the .. `.`.-`
vehicle speed is less than or equal to the preset ~ ?:,i`~
speed. "`~
?; ~
20In another aspect of the present invention,
:certain onQs of the plurality of inputs are ..
. connectable to a vehiclQ alarm system that provides . .. ~
.the control circuit with a plurality of alarm ... `-
con~rol signals, each of which is associated with a ...
25~ different vshicle alar~ condition. The control
~` : circuit is operable in responsQ to tha alarm control
:signals to eause the v hicle horn to produce a `-~
plurality of sounds, each indicative of a different ~ -
one of the vehicle alarm conditions. .. ~:
. `~
The horn system of the present invention ~ ~
advantageously pormits use of a conventional vehicle ~.. ``
.,~
: , .:
VO 941265;; 2 1 3 ~ 3 4 3 PCT11~593/05911
.,., ~ .
-- 1 0
horn or horns to indicate the occurrence of
different events and allows nearby persons to
determine which of the different events occurred
based on the sound produced by the vehicle horn or
horns. Thus, the present invention eliminates the
need ~or separate sound transducers used for such ~ .
: things as vehicle alarms and backing-up warnings.
The invention can also be used to call attention to :: :
certain vehicle operating conditions such as fuel - ::
level, tire pressure, etc. For any such `
arrangement, the horn syste~ would be coupled to a ~.
sensor that monitors the operating condition and
would be ~on~igured to generate a unique sound . :
~: related to that operating condition.
BRSB~ DX8CaIPTIO~ OF T~E 9RA~I~8~
:- ' ~ ,:
The preferred exemplary embodiments of the
present invention will hereinafter be described in ~ ~
: 20 conjunction with thQ appended drawings, wherein like ~:
~ designations denote like sl2ments, and: ~
~, :
Figus- 1 is a simplified block diagram of a
preferred embodiment of the vehicle horn system of
~ 25 the pres~nt invention;
-j F~guro 2 is a block diagram as in Fig. 1 -~
: showing some of the datail of the controller; and
Figuro 3 is a block diagram of an energizing
circuit operable as the horn drivers of Figs. 1 and :~
2. `~
~VO91/265;5 21 3~ 3 4 3 PCT~S93/0;9ll ~ ~
-', ''..
- ~. 1 - . " .. . -
. :. . . ~...
DE8CRIP~ION OF T~E PREFERRED E~BODI~EN~
As shown in Fig. 1, a vehicle horn system of -`
the present invention, designated generally as 10, -; `
includes a controller 12, a high frequency horn 14,
a low frequency horn 16, a driver i8 for horn 14,
and a second driver 20 ~or horn 16. Controller 12
is a control circuit having a plurality of inputs
.: , . .
connected to various vehicle electrical devices,
each of which is operable to provide controller 12 .
with an indication of the occurrence of some event
for which an audible alert is desired. Such an
indication can be, for example, a change in the ~-
voltage or impedance seen by controller 12 on its `
input.
.`..'... .
In general, controller 12 monitors these
- ~ e}ectr1cal devices and, in response to an indication
of~the occurrence o~ one of the events, operates
20~ hoxn 14 and/or horn 16 to produce a speci~ic sound
~ " .. .- . . i . ~
that is associatad with t~at e~ent. In the `~
illustrated embodiment, controller 12 has ~he
followin devices connected to different ones of its
input-:~ a speed sensor 22, a horn switch 24, a
2s~ reverse switch 26, an alarm ~system 2~, and an l ~-
optional device 30 that can be, for~example, a two- ~-
state sensor that monitors a vehicle operating ~
- ~ condition. ; ~-
: .. , . ~., .,
~ 30 Speed sensor 22 can be a tachomet-r or other ~-
`` ~ device that provides a signal representa~ive of
~` ` vehicle speed. ~orn switch 24 can be, for example~
; ~ ` ". '-',. .:
~ w09~/26s5; 213~3~3 PCT~S~3/Oi911
.
:; .`
- ~2 -
,~
a conventional switch mounted on the ve~icle
steering wheel with contacts that close upon
pres~ure being exerted on the steering wheel pad.
Reverse switch 26 can be, for example, a
conventional switch coupled to the gear switch lever
to detect placement of the vehicle into reverse
~ear.
Alarm system 28 has four connections to -
- lO controller 12, one of which is used for indicating
that the alarm has been violated and the ot~er three
of which are used for indicating certain changes in
the status of the ala~m system, namely, when the
alar~ has been armed, dis-armed, or mis-armed. Of
course, thase ~our inputs could be provided on a
single line using different voltaqe, current, or
impedance levels to indicate the various alarm
conditions.
~,
~;~ 20 Referring now to Fig. 2, a more specific
;~ implementation of controller 12 is shown as it would
be utiliz~d in horn system 10. Controller 12
` includes a sound selact circuit 40, a group of pulse
- generators 42, an enable circuit 44, a summing
junction or logical OR 46 feading driver 18, and a
second logical OR 48 feeding driver 20. Sound
select 40 is provided with most of the inputs to
controller 12 and is connected to each of the pulse
~ .
generators 42. In particular, sound select 40 is
- 30 separately conr.ected to a horn pulse generator 50,
a reverse pulse generator 52, an arm alarm pulse
generator 54, a dis-arm alarm pulse generator 56, a
.
.
~O 94/265;; PCTIUS93/0;911 ~ -
~ 2 1 3q 3 4 3
..... "- .,,
,.. . ..
- 13 ~
:' .'. ' '` .'
mis-arm alarm pulse generator 58, and a alarm
violated pulse generator 60. Although only speed ... ~` `
sensor 22, horn switch 24, reverse switch 26, and
alarm system 28 are shown connected to controller .
12, it will be appreciated by those skilled in the
art that other vehicle electrical devicPs can be ~:.
connected to additional inputs to sound select 40 to . .,:.
thereby indicate the occurrence of other events for
which an audible alert is desired. Controller 12:~
would then contain additional pulse generators 42.;
coupled between sound select 40 and logical ORs 4~
48. :
'.: ''.
Upon an indication of the occurrence of an ..
event on one of the inputs to controller 12, sound
: select 40 causes the one of the pulse generators 42
associated with that event to generat~ a pulse or
pulse train. The signal generated is unique froma~
: the signals genérated by the other ones of the pulse
~:: `20 generators 42 and is used to drive high horn 14
and/or low horn 16 via their drivers 18 and 20. The
~ pulse or pulse train generated by ~àch of the pulse
: generators 42 is preselected to produca a sound from
`............... : horns 14 andJor 16 that is appropriate in terms of
loudness, duration, and rep~tition rate for ~he
event that it is announcing.
. ~ .
Sound select 40 monitors the inputs of
controller 12 that are connec~ed to horn switch 24, ~:
reverse switch 2S, and alarm system 28. The inputs -~
to controller 12 from these vehicle electrical
devices can be independently connected directly to ` .
. :
~ WO 94/26~i; 2 1 3~ 3 4 ~ PCT/US93/05911
their associated ones of the pulse generators 42.
If so, the concurrence on two or more inputs of
controller 12 of the indication of different events
would cause simultaneous operation of two or more of
the pulse generators 42 with a resulting horn output
that is a combination of the output of those pulse
generators.
Preferably, however, sound select 40 is
configured to resolve conflicts between simultaneous
input signals from the various electrical devices so
that only one of the pulse generators 42 causes
operation of horn 14 and/or 16 at any one time.
Generally, this is done on a first-come first-served
lS basis so th~t if, for example, reverse switch 26
closes while horn switch 24 is closed, reverse pulse
genera~or 52 remains disabled until horn switch 24
is re-opened. Even more preferably, horn switch 24
receives priority over the indic tion on other
inputs of other events. Thus, sound select 40 is
configured such t~at if, for example, the vehicle is
placed in reverse with reverse switch 26 thereby
closin~ and causing operation of reverse generator
52, subRequent activ~tion of horn switch 24 is given
priority and sound seleet 40 disables operation of
reverse generator 52 and enables operation of horn
~'~ generator 50. If reverse switch 26 remains closed
after horn switch 24 is re-opened, then operation of
~ reverse generator 52 would resume.
`~ 30
Additionally, sound select 40 could be
configured to store and queue signals receiv~d on
~l/O 91/2655' PCT/lJS93/05911
, 213q343 - ~
- 15 -
: `,: :.:. :..
: -. : :::
its inputs so that if, for instance, a pulse is
provided to controller 12 on the mis-arm alarm input
while horn switch 24 is being activated, the
occurrence of that pulse could be stored and, after
activation of horn switch 24 ends, used to operate
mis-arm pulse generator 58 even though the siqnal on
the mis-arm input is no longer present.
Furthermore, as will be appreciated by those skilled
in the art, the enabling and disabling of the pulse
generators 42 that is provided by sound select 40
could also be implemented between the pulse
generators 42 and logical ORs 46, 48. This could be
done by gating the outputs of the pulse genarators
42.
I5
Preferably, the pulse generators 42 are
configured to produce signals for driving a three-
wire electronically-switched type horn. Before
describing the operation of pulse generators 42, a
suitable three-wire electronically-switchad type
horn 62 suitable for use as horns 14 and 16
(including th~ir drivers) will be descri~ed in
connection with Fig. 3. Three-wire horn 62
comprises an electric horn 64 and an energizing
circuit 66 having a signal ganerator 68 and a solid
state power switch in the form of a power MOSFET 70.
Circuit 66 is shown for energizing horn 64 as it
, , ~, .: ., .
would be connected in an automotive vehicle. Horn
64 has its electromagnet coil 72 connected in series ~-
circuit with a DC voltage source 74 and power MOSFET
70. More specifically, power MOSFET 70 has its
source 76 connected to ground and its drain 78 is
: , ~
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~ w0941265;5 21 3q3 ~ 3 PCT~S93/05911
- 16 -
connected through coil 72 to the positive terminal
of the voltage source 74, through an unswitched
power circuit, tha negative terminal of voltage
source 74 being connected to ground. A horn switch
24', which is manually actuable by the vahicle
driver, has its fixed contact connected directly t~
ground and its movable contact connected through an
on/off circuit 80 to t~e positive terminal of
voltaga source 74. When horn switch 24', is closed,
the battery voltage is applied by on/off circuit 80
to the input of a voltage regulator 82. Voltage
regulator 82 supplies a regulated supply voltage for
an oscillator 84 and a time on compensator 86.
Oscillator 84 is a sawtooth osrillator having an
output frequency determined by a capacitor 88 and an
adjustable resistor 90. Time on compensator 86
develops a control signal which is combined with the
output of oscillator 84 to generate a pulse train
which is applied to a driver stage 92. The control
signal produced by time on compensator 86 determines
~`~ the duty cycle of the pulse train and i5 adjustable
by an adjustable resistor 94. The pulse train
output of driver stage 92 is applied to tha gata 96
of power MOSFET 70 which is switched on and off by
25 ~ the pulse train. A snubber 98 is connected from the
drain to the gate of power MOSFET 70 to protect the
. circuit from transients. Energizing circui~ 66 can
be implemented on a printed circuit board located on
or within a housing 100 of electric horn 64.
U.S.S.N. 684,693, filed April 12, 1991 in the name
of Wilson et al. and assigned to the assignee of the
presant invention, provides further details sn a
,~WO 94126555 PCT/U593/05911
-' '` 2 1 3q 3 4 3 , .~ . ". ,
` ..:' .':.~, ' '
~,.-~,..,,.,., ",
-- 1 7 ~
'`' ''' . '
specific implementation of horn 62 and is hereby ~
incorporated by reference. ` ~;
As will now be appreciated, horn 62 is an ;
electronicalIy-switched horn because coil 72 is
driven by a solid state switching circuit rather
than by the more conventional mechanical switches
describsd above. Additionally, horn 62 is a three-
wire horn because, in order to connect it as it
would be implemented on an automotive vehicle, ~ -
three-wires are used: one leading to DC voltage
source 74 (e.g., the vehicle battery), one providing
a ground return path, and one leading to horn switch ~ ;~
24'.
Horn 62 can suitably be employed ~or high
horn 14 and its driver-18 of Figs. l and 2. To do `
so, terminal 102 of horn 62 (shown in Fig. 3 as
bein~ connected to horn switch 24') would be coupled ~ ~
- 20 to the output of logical OR 46 of Figs. 1 and 2. In ~`
a like manner, a horn 62 can be used for low horn 16 1~ ;
and its driver 20 of ~i~s. 1 and 2, the only
difference being that high hsrn 14 has a higher~ ~`
res~nant frequency of mechanical vibration than low
- ~ 25 horn 16 and resistors 90 and 94 and capacitor 88 for `~;
both horns will be selected for proper opera~ion of
each horn at its resonant frequency. ~-
.
; Referring again to Fig. 2, t~e preferred
profiles for the pulses and pulse trains generated
by each of the pulse generators 42 will now be
described. For the purpose of describing these ` ;
~; . '"' .~ '
.: :
~ 094l26;i; 2 ~ 3q 3 4 3 ~cT~ss3lo;sll
- 18 -
.
signals and the operation of controller 12, an
active hi~h convention is utilized so that, when
disabled, each of the pulse generators 42 output a
logical zero. However, as discussed below, any or
all of the signals generated by controller 12 can be
activP low, the only requirement being that the
logic functions combining the various signals be
altered accordingly.
Horn pulse generator 50 generates a pulse of
indefinite duration, the pulse width ~eing
determined solely by the length of time that horn
switch 24 is activated. Thus, horn generator 50
produces a continuous DC level (logical one) as long
.
as horn switch 24 is depressed. This signal is
provided directly to logical OR 48 to automatically
cause op~ration of low horn 16. This signal is
gated by a logical AND 110 which passes the signal
" ` ~ only if its other input is ~lso a logical one. The
2Q ~ other input to logical AND 110 is connected to the
output of a co~parator 112 that receivas as its
inputs ~h~ output from speed sensor 22 and a presat
speed-114 which provides a minimum vehicle speed for
~;~ ` which operation of high horn 14 is enabled. In
~` ` 25 ~`particular, comparator 112 compares the vehicle
~speed as determined by speed sensor 22 with preset
, ! speed 114. If the vehicle speed is greater than
preset speed 114, then comparator 112 outputs a
logical one, thereby passing the output of horn
generator 50 (whether a logical zero or one) to
driver 18. Conversely, if the vehicle speed is less
than or egual to preset speed 114, then comparator
:
~ '
.
~vos~/265s; PCT~S93/059
~., 2 ~ 3q 3 4 3 ' ~
. : ., ~:
,'~ :'''`.''
- 19 - ' .. ,.:~
112 outputs a logical zero, thereby preventing the
passage of the output of horn generator 50 to
logical OR 46. Since only one horn is operated at
lower speeds, the normal horn sound produced by horn
system 10 has a lower decibel level in situations
involving a stopped or relatively slow-moving
vehicle than in situations in which the vehicle is -~
moving guickly and both horns are utilized. -~
: ::: -: -
; 10 Upon closure of reverse switch 2~, reverse
generator 52 provides a pulse train of nine
millisecond pulses at a repetition rate of one pulse ~
every thirty-eight milliseconds. This pulse train ;~-
is generated for five hundred milliseconds at a rate
., .
of one hertz until reverse switch 26 is re-opened.
This signal is provided directly to logical OR 46 to
thereby operate high horn 14~ This signal is also
provided to a delay circuit 116 which provides a
nine~een millisecond delay before providing the
signal to logical OR 48 to thereby operate low horn
6. Thus, closure of reverse switch 26 results in
high and low horns 14 and 16 being alternately
pulsed for nine milliseconds at a relatively hiqh
r-petition rate for a period of half a second,
~ollowed by one half of a second of silence,
followed by another set of alternating nine
millisecond pulses, and so on until reverse switch
26 is re-opened.
Upon sound selector 40 receiving a signal
from alarm system 28 that the vehicle alarm ha~ been
armed, arm pulse generator 54 produces a single
. A . ~ . ., ~
~vos~/26~5s 2 1 3 q 3 4 3 PCT~'593/05911
- 20 -
pulse having a nine millisecond duration that is
provided only to logical OR 46 and, hence only to
high horn 14. Similarly, upon sound selector 40
receiving a signal from alarm system 28 that the
vehicle alarm has been dis-armed, dis-arm pulse
generator 56 produces a single pulse having a nine
millisecond duration that is provided only to
logical OR 48 and, hence only to low horn 16. Mis-
arm generator 58 also produces a single nine
millisecond pulse, but this pulse is first provided
to logicaI OR 46 to operate high horn 14 and then,
after a three hundred twelve millisecond delay
produced by a delay circuit 118, is provided to
~` ~ logical OR 48 to operate low horn 16.
Upon sound selector 40 receiving a signal
from alarm system 28 that the vehicle alarm has been
violated, alarm violated pulse generator 60 produces
a pulse train of one half of a second pulses at a
repetition rate of one hertz. This pulse train is
provided simultanQously to both logical ORs 46 and
48 so that horns 14 and 16 are operatad together.
; ; It wi}l be appreciated:~that, of the above
pulsès and pulse trains, the minimua pulse width is
nine milliseconds. Thus, for a horn operating at a
frequency of four-hundred hertz, signal generator 68
pul~es power MOSFET 70 on every two and one half
; milliseconds, thereby operating ~OSFET 70 for three
~ 30 full cycles during the nine millisecond pulse.
:;:
. . .. . .: , - .
~og~/265;; pcTlus93los9ll ~
.. :,.................................................................. : .
2 ~ ~q ~ ~1 3
- 21 -
:
The operation of controller 12 has been
des~ribed using an active high convention. It will
of course be appreciated that controller 12 can be
implemented with some or all of the Yarious signals
being active low and the functions provided by
elements 46, 48, and llO would then be chosen
accordingly. Moreover, if the convéntion used
throughout is active low, then logical AND llO could
be replaced by a logical OR and logical Ors 46 and
48 could be replaced by logical ANDs. Horn pulse
generator 50 would then not be needed and horn
switch 24 could then be connected directly to
element 48 (now a logical AND), as indicated by the
brok~n lines in Fig. 2. Horn switch 24 could even
be connected directly to on-off circuit 80 as horn
switch 24' is s~own in Fig. 3, with the signals from
the other pulse generators 42 being coupled to on~
off circuit 80 in any of various ways known to those
skilled in the art.
As mentioned above, horn system lO can be
implemented using mech~nically-switched type horns
rather than the electronically-switched type just
de~cribed. If a mechanically-switched type horn is
~ utilized, then the drivers lR and 20 would be
~`~ responsive to signals fro~ their respective logical
, . ~- :-, :
Ors 46 and 48 to connect their respective horns 14
and 16 to a DC power source such as the vehicle
battery. Additionally, In mechanically-switched
horns, the frequency or the outputted acoustic waves
~` ramps up from zero hertz to the resonant frequency
- of the horn. This~ ra~ping occurs relatively fast
```~: - `,'' :
W094/265;; PCT~S93/059ll
2~3q3~ :
and is not normally perceived by the human ear.
This effect, however, permits generation of
different sounds in a manner other than has been
described above. More specifically, different
sounds can be produced by controlling the amount of
time that power is applied to the horn. If, for
example, it takes a mechanically-switched horn ten
milliseconds to ramp up to its full natural
frequency, then by providing pulses to the horn of
four and one half milliseconds, the frequency
reached by the horn during each pulse will be
something less than the horn's resonant frequency.
The result will be a different sound at a decibel
:
level less than when the horn is being operated at
its resonant ~requency. Moreover, if the repetition
rate of the pulses is high enough, the sound
` produced will be perceived as a continuous sound.
Thus, various sounds can be produced in this manner
, . ,
by configuring pulse generators 42 accordingly.
It will thus be apparent that~there has been
provided in accordance with the ~resent invention a
vehicle horn system which achieves the aims and
advanta~es specified herein. It will of course be
~understood that the foregoing description i~ of
preferred exemplary embodimen~s of the invention and
that the invention is not limited to the specific
embodiments shown. Various changes and
~` modifications will become apparent to those skilled
in the art and all such variations and modifications
are intended to come within the spirit and scope of
the appended claims.
