EP0655980A1

EP0655980A1 - Multi-sound vehicle horn system

Info

Publication number: EP0655980A1
Application number: EP93916647A
Authority: EP
Inventors: Juris Turlais; Stuart D. Davis; Edward G. Faris; Steven L. Dietrich; Jeffrey G. Hertenstein
Original assignee: Sparton Corp
Current assignee: Sparton Corp
Priority date: 1993-05-18
Filing date: 1993-06-21
Publication date: 1995-06-07
Also published as: EP0655980A4; CA2139343A1; KR950702481A; JPH07507523A; WO1994026555A1

Abstract

A vehicle horn system (10) is disclosed which provides a plurality of different sounds, each indicative of the occurence of a different event. The horn system includes a vehicle horn (14), a horn switch (24), and a control circuit (12) having a plurality of inputs, one of which is coupled to the horn switch (24). Activation of the horn switch (24) causes the control circuit (12) to operate the horn (14) to produce a standard horn warning. Other events for which the horn system produces an audible alert include backing-up of the vehicle and changes in the vehicle alarm status. The horn system can include a vehicle alarm sensor (24) and a second vehicle horn (16) that produces a different sound than the first horn (14). The control circuit (12) is configured to operate only one of the horns when the vehicle is travelling below a certain speed and to operate both horns when the vehicle is travelling above that speed.

Description

MULTI-SOUND VEHICLE HORN SYSTEM

TECHNICAL 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 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 switch, produces one of a pair of sounds depending upon vehicle speed.

BACKGROUND OF THE INVENTION

The use of sound generating devices on vehicles to produce sounds that convey information to persons within and without the vehicle is well established. 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 information to occupants of the vehicle include buzzers or other sound transducers which indicate that, for example, a door is ajar, seat belts should be fastened, or the headlights have been left on. 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 housing extends axially of the coil. A magnetic plunger on the diaphragm extends toward the pole piece for imparting motion to the diaphragm in response to periodic energization of the coil. The diaphragm provides a resilient suspension of the plunger for reciprocating motion relative to the coil; it has a spring characteristic whereby the diaphragm and the mass carried by it have a resonant freguency of mechanical vibration. The coil is energized from the vehicle battery through a mechanically actuated switch which is alternately opened and closed by movement of the plunger with the diaphragm. A vehicle horn of this kind is sometimes referred to as a mechanically-switched type horn. A specific example of this type of horn is described in U.S. Patent No. 4,813,123, granted March 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. See, for example, U.S. Patent No.

5,049,853, granted September 17, 1991 to Yoon, the disclosure of which is hereby incorporated by 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 freguency. The solid state driver has an electronic timer adjustable to the freguency of the diaphragm assembly and switches a solid state power output stage to drive the diaphragm synchronously with the timer frequency. A driver output stage 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, 1991 in the name of Wilson et al. and assigned to the assignee of the present invention.

Regardless of the type or freguency of the horn, vehicle horn systems 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 generates a plurality of frequencies provides a sound that has a pleasing effect and yet is effective for its intended purpose. Multiple frequency sound generation has been accomplished in many ways. For example, U.S. Patent No. 2,910,688, granted October 27, 1959 to Kelley et al., discloses a circuit arrangement which includes two oscillators that operate 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 frequencies is disclosed in U.S. Patent No. 4,486,742, granted December 4, 1984 to 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 modulated at a frequency equal to the frequency separation between the two resonant frequencies of the piezoelectric.

Yet another way to generate 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 of the horns is designed for relatively low frequency operation and the other for relatively high frequency operation. For example, one horn may be designed to have a resonant frequency of four hundred hertz and the other designed to have a resonant frequency of five hundred hertz.

In all of these arrangements, the various frequencies are generated simultaneously to produce a single horn sound. In the Kelley et al., Grace, and Kudo patents mentioned above, a single transducer (i.e., loudspeaker or piezoelectric) is energized by a waveform that produces a single sound 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 alarm 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. 4,040,050, granted August 2, 1977 to Nunn, Jr. , disclose circuits for emergency vehicles that permit switching between "wail" and "yelp" siren sounds. None of these patents, however, disclose or suggest utilizing a standard vehicle horn for producing these sounds in addition to the usual horn warning sound that is produced upon activation of the vehicle horn switch. The patent to Nunn, Jr. 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. 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 needs attention. Similarly, U.S. Patent No. 4,421,052, granted December 20, 1983 to Cook, discloses a tire pressure signalling device that generates an acoustic signal when the tire pressure falls below a predetermined level. The acoustic signal is detected 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 teach using a separate sound transducer (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 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 discloses 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 control 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 Tibbetts, and U.S. Patent No. 2,694,806, granted November 16, 1954 to Johnson.

SUMMARY OF THE INVENTION

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 coupled to the vehicle horn, and a control circuit coupled to the vehicle horn and having a plurality of inputs for providing the circuit with a plurality of input signals. The 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 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 or an electronically-switched type horn.

Preferably, the control circuit is configured to resolve conflicts between inputs occurring simultaneously. In doing so, activation of the 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 freequency that is different than the resonant 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 input signals. The outputs of the two horns can be combined in various ways to produce different sounds that are associated with different events. 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 connected 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. Preferably, the control circuit is configured to operate both of the vehicle horns when the 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 activated and the vehicle speed is less than or equal to the preset speed. Preferably, only the horn having the lower resonant frequency is operated when the vehicle speed is less than or equal to the preset speed.

In another aspect of the present invention, certain ones of the plurality of inputs are connectable to a vehicle alarm system that provides the control circuit with a plurality of alarm control signals, each of which is associated with a different vehicle alarm condition. The control circuit is operable in response to the alarm control signals to cause the vehicle 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 permits use of a conventional vehicle 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 for 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 system would be coupled to a sensor that monitors the operating condition and would be configured to generate a unique sound related to that operating condition.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred exemplary embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and:

Figure 1 is a simplified block diagram of a preferred embodiment of the vehicle horn system of the present invention;

Figure 2 is a block diagram as in Fig. 1 showing some of the detail of the controller; and

Figure 3 is a block diagram of an energizing circuit operable as the horn drivers of Figs. 1 and 2. DESCRIPTION OF THE PREFERRED EMBODIMENT

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 18 for horn 14, and a second driver 20 for 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 electrical devices and, in response to an indication of the occurrence of one of the events, operates horn 14 and/or horn 16 to produce a specific sound that is associated with that event. In the illustrated embodiment, controller 12 has the following devices connected to different ones of its inputs: a speed sensor 22, a horn switch 24, a reverse switch 26, an alarm system 28, and an optional device 30 that can be, for example, a two- state sensor that monitors a vehicle operating condition.

Speed sensor 22 can be a tachometer or other device that provides a signal representative of vehicle speed. Horn switch 24 can be, for example, a conventional switch mounted on the vehicle steering wheel with contacts that close upon pressure 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 gear.

Alarm system 28 has four connections to controller 12, one of which is used for indicating that the alarm has been violated and the other three of which are used for indicating certain changes in the status of the alarm system, namely, when the alarm has been armed, dis-ar ed, or mis-armed. Of course, these four inputs could be provided on a single line using different voltage, current, or impedance levels to indicate the various alarm conditions.

Referring now to Fig. 2, a more specific implementation of controller 12 is shown as it would be utilized in horn system 10. Controller 12 includes a sound select circuit 40, a group of pulse generators 42, an enable circuit 44, a summing junction or logical OR 46 feeding 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 separately connected 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 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 devices 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 46, 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 generate a pulse or pulse train. The signal generated is unique from the signals generated by the other ones of the pulse 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 each of the pulse generators 42 is preselected to produce a sound from horns 14 and/or 16 that is appropriate in terms of loudness, duration, and repetition rate for the event that it is announcing.

Sound select 40 monitors the inputs of controller 12 that are connected to horn switch 24, reverse switch 26, and alarm system 28. The inputs to controller 12 from these vehicle electrical devices can be independently connected directly to 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 basis so that if, for example, reverse switch 26 closes while horn switch 24 is closed, reverse pulse generator 52 remains disabled until horn switch 24 is re-opened. Even more preferably, horn switch 24 receives priority over the indication on other inputs of other events. Thus, sound select 40 is configured such that if, for example, the vehicle is placed in reverse with reverse switch 26 thereby closing and causing operation of reverse generator 52, subsequent activation of horn switch 24 is given priority and sound select 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.

Additionally, sound select 40 could be configured to store and queue signals received on 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 signal 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 generators 42.

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-switched type horn 62 suitable for use as horns 14 and 16 (including their drivers) will be described in connection with Fig. 3. Three-wire horn 62 comprises an electric horn 64 and an energizing circuit 66 having a signal generator 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 connected through coil 72 to the positive terminal of the voltage source 74, through an unswitched power circuit, the negative terminal of voltage source 74 being connected to ground. A horn switch 24' , which is manually actuable by the vehicle driver, has its fixed contact connected directly to ground and its movable contact connected through an on/off circuit 80 to the positive terminal of voltage 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 oscillator 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 is adjustable by an adjustable resistor 94. The pulse train output of driver stage 92 is applied to the gate 96 of power MOSFET 70 which is switched on and off by 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 circuit 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 present invention, provides further details on a specific implementation of horn 62 and is hereby incorporated by reference.

As will now be appreciated, horn 62 is an electronically-switched horn because coil 72 is driven by a solid state switching circuit rather than by the more conventional mechanical switches described 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 for 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 being connected to horn switch 24') would be coupled 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 and its driver 20 of Figs, l and 2, the only difference being that high horn 14 has a higher resonant frequency of mechanical vibration than low horn 16 and resistors 90 and 94 and capacitor 88 for both horns will be selected for proper operation of each horn at its resonant frequency.

Referring again to Fig. 2, the 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 signals and the operation of controller 12, an active high 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 active 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 being 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 operation of low horn 16. This signal is gated by a logical AND 110 which passes the signal only if its other input is also a logical one. The other input to logical AND 110 is connected to the output of a comparator 112 that receives as its inputs the output from speed sensor 22 and a preset speed 114 which provides a minimum vehicle speed for which operation of high horn 14 is enabled. In 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 equal to preset speed 114, then comparator 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 quickly and both horns are utilized.

Upon closure of reverse switch 26, 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 nineteen millisecond delay before providing the signal to logical OR 48 to thereby operate low horn 16. Thus, closure of reverse switch 26 results in high and low horns 14 and 16 being alternately pulsed for nine milliseconds at a relatively high repetition rate for a period of half a second, followed 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 has been armed, arm pulse generator 54 produces a single 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 logical 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 simultaneously to both logical ORs 46 and 48 so that horns 14 and 16 are operated together.

It will be appreciated that, of the above pulses and pulse trains, the minimum pulse width is nine milliseconds. Thus, for a horn operating at a frequency of four hundred hertz, signal generator 68 pulses power MOSFET 70 on every two and one half milliseconds, thereby operating MOSFET 70 for three full cycles during the nine millisecond pulse. The operation of controller 12 has been described using an active high convention. It will of course be appreciated that controller 12 can be implemented with some or all of the various signals being active low and the functions provided by elements 46, 48, and 110 would then be chosen accordingly. Moreover, if the convention used throughout is active low, then logical AND 110 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 broken lines in Fig. 2. Horn switch 24 could even be connected directly to on-off circuit 80 as horn switch 24' is shown 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 10 can be implemented using mechanically-switched type horns rather than the electronically-switched type just described. If a mechanically-switched type horn is utilized, then the drivers 18 and 20 would be responsive to signals from 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 of the outputted acoustic waves ramps up from zero hertz to the resonant frequency of the horn. This ramping occurs relatively fast 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 freguency, 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 frequency. 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 present invention a vehicle horn system which achieves the aims and advantages specified herein. It will of course be understood that the foregoing description is of preferred exemplary embodiments 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.

Claims

What is claimed is:

1. In a vehicle horn system of the type having a vehicle horn and a horn switch coupled to said vehicle horn, the improvement comprising:

a control circuit coupled to said vehicle horn and having a plurality of inputs for providing said circuit with a plurality of input signals, said control circuit being operable to control the sound produced by said vehicle horn in accordance with the input signals;

wherein said horn switch is coupled to a first one of said plurality of inputs to thereby provide said control circuit with a first one of the input signals upon said horn switch being activated.

2. A vehicle horn system as defined in claim 1, wherein said vehicle horn has a resonant frequency of mechanical vibration and said control circuit is responsive to activation of said horn switch to operate said vehicle horn at said resonant frequency.

3. A vehicle horn system as defined in claim 2, further comprising a second vehicle horn having a second resonant frequency of mechanical vibration that is different than said first- mentioned resonant frequency, wherein said control circuit is coupled to said second vehicle horn and is operable to control the sound produced by said second vehicle horn in accordance with the input signals.

4. A vehicle horn system as defined in claim 3, further comprising a sensor coupled to a second one of said plurality of inputs, said sensor being operable to provide said second input with a signal representative of vehicle speed;

wherein said control circuit is configured to operate both of said vehicle horns when said horn switch is activated and the vehicle speed is greater than a predetermined value and, further, wherein said control circuit is configured to operate only one of said vehicle horns when said horn switch is activated and the vehicle speed is less than or equal to said predetermined value.

5. A vehicle horn system as defined in claim 1, wherein said vehicle horn is a mechanically-switched type horn.

6. A vehicle horn system as defined in claim 1, further comprising an electronically- switched type horn that includes an electric horn and an electronic switch for selectively supplying power to said electric horn.

7. A vehicle horn system as defined in claim 1, wherein certain ones of said plurality of inputs are connectable to a vehicle alarm system that provides said control circuit with a plurality of alarm control signals, each of which is associated with a different vehicle alarm condition, said control circuit being operable in response to the alarm control signals to cause said vehicle horn to produce a plurality of sounds, each indicative of a different one of said vehicle alarm conditions.

8. A vehicle horn system for selectively producing a plurality of different sounds, each of which is associated with a different event, comprising:

a vehicle horn; and

a control circuit having first and second inputs, said first input being connectable to a first electrical device that, via said first input, is capable of providing said control circuit with an indication of the occurrence of a first event, said second input being connectable to a second electrical device that, via said second input, is capable of providing said control circuit with an indication of the occurrence of a second event;

said control circuit being operable to cause said vehicle horn to produce a first sound when said first input is provided with an indication of the occurrence of said first event and, further, said control circuit being operable to cause said vehicle horn to produce a second sound when said second input is provided with an indication of the occurrence of said second event.

9. A vehicle horn system as defined in claim 8, further comprising a horn switch coupled to said first input to cause said control circuit to operate said vehicle horn when said horn switch is activated, whereby said first event is the activation of said horn switch.

10. A speed-responsive vehicle horn system, comprising:

a first vehicle horn having a first resonant frequency of mechanical vibration;

a second vehicle horn having a second resonant frequency of mechanical vibration different than said first resonant frequency;

a control circuit responsive to first and second input signals and coupled to said first and second horns to control the operation of said horns;

a horn switch operable by the vehicle operator to produce said first input signal; and

a sensor operable to generate said second input signal in accordance with vehicle speed; wherein said control circuit is configured to operate said first and second vehicle horns when said horn switch is activated and the vehicle speed is greater than a predetermined value and to operate only said first vehicle horn when said horn switch is activated and the vehicle speed is less than or equal to said predetermined value.