On-vehicle receiving system

An on-vehicle receiving system for optimizing the receiving performance of a radio receiver and a remote controlled receiver, whereby a remote-controlled receiver and a radio receiver share an on-vehicle antenna. A key detector for detecting whether an ignition key is fitted into a key cylinder of the vehicle is employed and a selector switch for connecting the on-vehicle antenna selectively to the remote-controlled receiver or the radio receiver are incorporated. When the key detector detects that the ignition key is fitted into the key cylinder, the selector switch selects the radio receiver. When it is detected that the ignition key is not fitted into the key cylinder, the remote-controlled receiver is selected. In one embodiment, a remote-controlled receiver and a radio receiver share not only an on-vehicle antenna but also part of receiving equipment. The remote-controlled receiver and radio receiver can also share the frequency and modulation form employed. In another embodiment, the detector is designed to detect whether the vehicle ACC switch is turned on by the ignition key instead of whether the ignition key is fitted into the key cylinder.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an on-vehicle receiving system. More 
particularly, this invention is concerned with an on-vehicle receiving 
system including a radio receiver for receiving an AM or FM broadcast or a 
TV audio broadcast and a remote-controlled receiver for receiving a remote 
control signal transmitted from a hand-held remote unit to operate a 
keyless entry system or a vehicle security system. 
2. Description of the Related Art 
It is inconvenient to have to use a conventional key to lock a door when 
leaving a vehicle and to have to use the same key to unlock the door when 
getting into the vehicle. In an effort to alleviate this nuisance, keyless 
entry systems have been developed. With a keyless entry system, when a 
user presses a lock button on a hand-held remote unit after getting out of 
the vehicle, a radio signal carrying a remote control signal that 
represents a lock command is propagated. The radio signal carrying the 
remote control signal is received by an antenna mounted on the vehicle and 
then fed to a remote-controlled receiver in the keyless entry system. The 
remote control signal is then received and modulated. Based on the 
resulting remote control signal, a controller controls a door lock device 
so that the door lock device locks the door. Further, when an unlock 
button on the hand-held remote unit is pressed in the vicinity of the 
vehicle, a radio signal carrying a remote control signal that represents 
an unlock command is propagated. The radio signal is received by the 
antenna, and then fed to the remote-controlled receiver in the keyless 
entry system. The remote control signal is then received and modulated. 
The controller then controls the door lock device so that the door lock 
device unlocks the door. 
An on-vehicle radio set is installed in almost all vehicles so that drivers 
can enjoy AM or FM broadcasts or TV audio broadcasts. In an effort to 
offer improved receiving performance with this kind of on-vehicle radio 
set, an antenna is usually installed in an elevated place on the vehicle 
by placing a pole upright on a front pillar or rear trunk of the vehicle 
or by attaching a metallic-foil pattern to a rear or front window of the 
vehicle. 
However, when an on-vehicle radio set and a keyless entry system are both 
installed in a vehicle, an antenna dedicated to the radio set which 
affords high receiving performance must be placed with higher priority 
outside the vehicle or on a window of the vehicle. Therefore, if an 
antenna dedicated to the keyless entry system is also placed outside the 
vehicle or on the window, the streamlined appearance of the vehicle is 
impaired and the possibility of breaking the antennas increases. In 
addition, the driver's field of vision can become too narrow. The antenna 
dedicated to the keyless entry system must therefore be installed inside 
the vehicle despite degraded receiving performance. In addition, it is not 
cost-effective to provide an antenna for both a radio set and a keyless 
entry system. 
The same problem arises when a vehicle security system, or any other 
on-vehicle remote-controlled unit is installed together with an on-vehicle 
radio set. 
SUMMARY 
According to the invention, an on-vehicle receiving system for optimizing 
the receiving performance of a radio receiver and a remote controlled 
receiver are provided with no restriction imposed on the antenna 
installation site. 
According to the present invention, a remote-controlled receiver and a 
radio receiver share an on-vehicle antenna. A key detector (also called a 
detector) for detecting whether an ignition key is fitted into a key 
cylinder of the vehicle is provided as well as a selector switch for 
connecting the on-vehicle antenna selectively to the remote-controlled 
receiver or the radio receiver. According to the invention, when the key 
detector detects that the ignition key is fitted into the key cylinder, 
the selector switch selects the radio receiver. When the key detector 
detects that the ignition key is not fitted into the key cylinder, the 
remote-controlled receiver is selected. Thus, according to the present 
invention, it is determined whether an ignition key is fitted into a key 
cylinder. When it is determined that the ignition key is fitted into the 
key cylinder, the on-vehicle antenna is switched over to the radio 
receiver. When the ignition key is not fitted into the key cylinder, the 
on-vehicle antenna is switched over to the remote-controlled receiver. 
Thus, the radio receiver and the remote-controlled receiver can share a 
single on-vehicle antenna. Once the on-vehicle antenna is installed in an 
optimal place on the vehicle, the remote-controlled receiver and the radio 
receiver can provide excellent receiving performance. The system according 
to the invention is therefore cost-effective. Furthermore, a user is 
relieved from a manual switching operation. Specifically, the on-vehicle 
antenna can be automatically switched over to whichever must be activated: 
the remote-controlled receiver or radio receiver. This is quite 
convenient. 
According to one embodiment of the invention, a remote-controlled receiver 
and a radio receiver share not only the on-vehicle antenna but also part 
of the receiving equipment. In addition, a key detector for detecting 
whether an ignition key is fitted into a key cylinder and a selector for 
selectively connecting the on-vehicle antenna to the shared part of 
receiving equipment to the remote-controlled receiver and radio receiver 
are incorporated. When the key detector detects that the ignition key is 
fitted into the key cylinder, the selector selects the radio receiver. 
When it is not detected that the ignition key is fitted into the key 
cylinder, the remote-controlled receiver is selected. 
The remote-controlled receiver and radio receiver can share not only the 
on-vehicle antenna but also the frequency and modulation form employed. 
This results in a reduction in cost. 
In one embodiment of the invention, the detector detects whether an ACC 
switch is turned on by means of the ignition key (i.e., the ignition is 
turned to the ACC position) instead of whether the ignition key is fitted 
into the key cylinder (an ACC switch is installed in virtually all 
vehicles). When the detector detects that the ACC switch is turned on, the 
selector selects the radio receiver. When it is detected that the ACC 
switch is off, the remote-controlled receiver is selected. Using the ACC 
switch, the present invention can be implemented even in a vehicle not 
having a switch for use in determining whether the ignition key is fitted 
into the key cylinder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a block diagram of one embodiment of the present invention. In 
FIG. 1, an on-vehicle radio set and a keyless entry system are integrated 
into a single unit 2. 
An on-vehicle antenna 1 is realized by placing a metallic pole upright on a 
front pillar or rear trunk of the vehicle or by attaching a metallic-foil 
pattern on a rear window of the vehicle. A single on-vehicle antenna is 
shared by the radio set and the keyless entry system. An integrated unit 2 
has the capabilities of a radio set and keyless entry system. A key switch 
3 is incorporated in a key cylinder (the key cylinder is not shown). When 
an ignition key is fitted into the key cylinder (not shown), a connection 
is made by switch 3 so that an output of +12 V is provided. When the 
ignition key is not fitted into the key cylinder, the connection is broken 
so that an output of 0 V is provided. A door lock device 4 for locking or 
unlocking a door of the vehicle is also provided. 
A selector switch 5 is connected to the on-vehicle antenna 1 which is 
controlled according to a detection signal sent from a comparator that 
will be discussed below. A radio receiver 6 is provided as well as a 
front-end processor 7 with a tuning frequency which is variable within a 
frequency band including an AM or FM broadcast band and which receives an 
intended broadcasting signal and converts it into an intermediate 
frequency signal. An intermediate frequency amplifier 8 is included as 
well as a detector 9 for detecting an AM or FM signal in an intermediate 
frequency (IF) signal. A multiplexer 10 is provided and a 
remote-controlled receiver 11. A front-end processor 12 with a tuning 
frequency which is fixed and which receives a radio signal carrying a 
remote control signal and converts it into an intermediate frequency 
signal is also included. An intermediate frequency (IF) amplifier 13 and a 
detector 14 based on a given modulation form which is consistent with the 
modulation form adopted for modulating the radio signal carrying the 
remote control signal are provided. 
A transformer 15 transforms a voltage of +12 V supplied from the key switch 
3 into a voltage of +5 V. A comparator 16 for providing a detection signal 
indicating whether the ignition key is fitted into the key cylinder is 
provided. Upon receiving +5 V from the transformer 15, the comparator 16 
provides a high-level signal. Upon receiving 0 V, the comparator 16 
provides a low-level signal. The key switch 3, transformer 15, and 
comparator 16 constitute a key detector for detecting whether or not the 
ignition key is fitted into the key cylinder. A drive circuit 17 is 
provided for driving the door lock device 4 under the control of a 
controller, which will be discussed below, and for allowing the door lock 
device 4 to lock or unlock a door. An radio interface 18 for selecting a 
radio broadcasting station or selecting an AM or FM mode is also provided. 
A controller 19 that is based on a microcomputer and is responsible for 
overall system control is provided so that when the comparator 16 sends a 
high level detection signal indicating that the ignition key is fitted 
into the key cylinder, the controller 19 controls the radio receiver 6 
according to an action of the radio interface 18 (more particularly, the 
controller controls tuning of the front-end processor 7 or controls the 
selecting of the AM or FM mode for the detector 9 and multiplexer 10). 
When the comparator 16 supplies a low level detection signal indicating 
that the ignition key is not fitted into the key cylinder, the controller 
19 controls a remote control unit. In particular, the controller 19 
decodes a remote control signal in response to a detection signal sent 
from the detector 14 and controls the drive circuit 17 according to the 
resultant remote control signal so that the drive circuit 17 actuates the 
door lock device 4. Controller 19 includes an operation program. A program 
capable of operating controller 19 having the functionality disclosed 
herein is easily provided by those skilled in the art. 
A radio signal carrying a remote control signal is transmitted from a 
hand-held remote unit (not shown). The integrated unit 2 is always 
energized by a battery (not shown) irrespective of the on or off state of 
an ACC switch (not shown). Moreover, when receiving a high-level signal 
from the comparator 16, the selector switch 5 is switched over to the 
radio receiver 6. When receiving a low-level signal, the selector switch 5 
is switched over to the remote-controlled receiver 11. 
The operation of the above discussed embodiment of the invention is as 
follows. When the driver fits the ignition key into the key cylinder, the 
key switch 3 is made. The key switch 3 provides a signal of +12 V and the 
transformer 15 converts this signal into a signal of +5 V. As a result, 
comparator 16 supplies a high-level signal indicating that the ignition 
key is fitted into the key cylinder. Then, the selector switch 5 is 
switched over to the radio receiver 6 and the on-vehicle antenna 1 is 
connected to the radio receiver 6, thereby enabling the radio receiver 6 
to receive a broadcast signal. At this time, the controller 19 ignores any 
signal fed from the remote control receiver 11 and controls the signal 
receiving function of the radio receiver 6 according to the action of the 
radio interface 18. The on-vehicle antenna 1 is conventionally located at 
an elevated place on the vehicle, therefore the driver can enjoy a radio 
broadcast with excellent receiving performance. 
When the driver removes the ignition key from the key cylinder to get out 
of the vehicle, the key switch 3 connection is broken. In this state, the 
key switch 3 provides a signal of 0 V and the transformer 15 5 provides a 
signal of 0 V. The comparator 16 therefore supplies a low-level signal 
indicating that the ignition key is not fitted into the key cylinder. The 
selector switch 5 is then switched over to the remote-controlled receiver 
11 and the on-vehicle antenna 1 is connected to the remote-controlled 
receiver 11, thereby enabling the remote-controlled receiver 11 to receive 
a signal. In this state, the controller 19 ignores any action of the radio 
interface 18 and controls a remote control unit according to a 
predetermined sequence in response to an input from the remote-controlled 
receiver 6. 
After the driver exits the vehicle, closes the door, and presses a lock 
button on a hand-held remote unit, a remote control signal representing a 
lock command is delivered by means of a radio signal. The radio signal is 
received by the on-vehicle antenna 1 and detected by the remote-controlled 
receiver 11 and then fed to the controller 19. The controller 19 then 
decodes the remote control signal according to detected information. Since 
the detected information is a lock command, the controller 19 controls the 
drive circuit 17 so that the door lock device 4 locks the door. 
When returning to the vehicle, the driver presses an unlock button on the 
hand-held remote unit. A remote control signal representing an unlock 
command is then delivered by means of a radio signal. The radio signal is 
received by the on-vehicle antenna 1, detected by the remote-controlled 
receiver 11, and then fed to the controller 19. The controller 19 decodes 
the remote control signal according to detected information. Since the 
detected information is an unlock command, the controller 19 controls the 
drive circuit 17 so that the door lock device 4 unlocks the door. 
Being located at an elevated place, the on-vehicle antenna 1 can reliably 
receive a radio signal carrying a remote control signal transmitted from 
the hand-held remote unit and supply it to the remote-controlled receiver 
11. Door locking or unlocking can therefore be achieved reliably owing to 
the excellent receiving performance provided by the elevated antenna. 
According to this embodiment of the invention, the single on-vehicle 
antenna 1 is shared by the radio receiver 6 and remote-controlled receiver 
11. Once the on-vehicle antenna 1 is installed in an optimal place on a 
vehicle, both the remote-controlled receiver 6 and radio receiver 11 
exhibit excellent receiving performance. This is cost-effective. Moreover, 
a driver will not be annoyed with a manual switching operation. Depending 
on whether a driver enters or leaves a vehicle, the on-vehicle antenna 1 
is automatically switched over to whichever must be activated; the radio 
receiver 6 or remote-controlled receiver 11. This is very convenient. 
Furthermore, the radio receiver 6 and remote-controlled receiver 11 share a 
single on-vehicle antenna without using a distributor. A signal received 
by the antenna can therefore be supplied to whichever must be activated; 
the radio receiver 6 or remote control receiver 11, without any power or 
time losses. 
In another embodiment of the invention, the input stage of the transformer 
15 is the conventional ACC switch (not shown) incorporated in the key 
cylinder instead of the key switch 3. When closed, the ACC switch provides 
a signal of +12 V. When open, the ACC switch provides a signal of 0 V. 
Thus, when the ACC switch is closed, the comparator 16 provides a 
high-level signal. The selector switch 5 is therefore switched over to the 
radio receiver 6. By contrast, when the ACC switch is open, the comparator 
16 provides a low-level signal. The selector switch 5 is therefore 
switched over to the remote-controlled receiver 11. Thus, the on-vehicle 
antenna 1 can be automatically switched over to whichever must be 
activated; the radio receiver 6 or remote-controlled receiver 1. An ACC 
switch is incorporated in virtually every vehicle. Using the ACC switch, 
the present invention can be implemented even in a vehicle which does not 
have a key switch 3 (see FIG. 1). 
FIG. 2 is a block diagram of an overall configuration of a second 
embodiment of the present invention. In the second embodiment, the 
on-vehicle radio set and the keyless entry system are stand-alone units. 
The components identical to those discussed in connection with FIG. 1 are 
assigned the same reference numerals. 
A separate on-vehicle radio set 20 is provided with this embodiment of the 
invention along with a separate keyless entry system 21. Each of the units 
is energized directly by a battery. The on-vehicle radio set 20 includes 
the selector switch 5, radio receiver 6, transformer 15, comparator 16, 
and radio interface 18, as well as a controller 190. The input terminal of 
the voltage is connected to the key switch 3. One terminal of the selector 
switch 5 is connected to the radio receiver 6, while the other terminal 
thereof is connected to an ANTin terminal of the keyless entry system 21. 
The controller 190 controls signal receiving in response to an action of 
the radio interface 18. 
The keyless entry system 21 includes the remote-controlled receiver 11 and 
drive circuit 17 as well as a controller 191. The input terminal of the 
remote control receiver is connected to the ANTin terminal. The output 
terminal of the drive circuit 17 is connected to the door lock device 4. 
When an ignition key is fitted into the key cylinder and the key switch 3 
is made, the selector switch 5 is switched over to the radio receiver 6. 
This allows reception of a radio broadcast. By contrast, when the key is 
not fitted into the key cylinder, and the key switch 3 is open, the 
selector switch 5 is switched over to the keyless entry system 21. This 
enables the remote-controlled receiver 11 to receive a remote control 
signal. The controller 191 decodes the remote control signal sent from the 
remote-controlled receiver 11. If the remote control signal represents a 
lock command, the controller 191 controls the drive circuit 17 so that the 
door is locked. If the remote control signal represents an unlock command, 
the controller 191 controls the drive circuit 17 so that the door is 
unlocked. 
According to this embodiment of the invention, even when a keyless entry 
system is separately installed in a vehicle with an on-vehicle radio set, 
the single on-vehicle antenna 1 can be commonly used. This is quite 
convenient. 
FIG. 3 is a block diagram of an overall configuration of a third embodiment 
of the present invention. In the third embodiment, the on-vehicle radio 
set and the keyless entry system use the same intermediate frequency and 
modulation/demodulation form and share an intermediate frequency amplifier 
and a detector which are included in receiving equipment. The components 
identical to those in FIG. 1 are assigned the same reference numerals. 
A selector switch 22 is provided for selectively supplying an output signal 
of a front-end processor 7 in a radio set and an output signal of a 
front-end processor 120 in a remote control unit to an intermediate 
frequency amplifier 8. When the comparator 16 provides a high-level 
signal, the selector switch 22 is switched over to the front-end processor 
7 while being interlocked with the selector switch 22. An intermediate 
frequency signal relating to the radio broadcast is then fed to the 
intermediate frequency amplifier 8. When the comparator 16 provides a 
low-level signal, the selector switch 22 is switched over to a front-end 
processor 120 so that an intermediate frequency signal relating to a 
remote control signal is fed to the intermediate frequency amplifier 8. 
The intermediate frequency signals supplied by the front-end processors 7 
and 120 represent the same intermediate frequency. The front-end processor 
7, selector switch 22, intermediate frequency amplifier 8, detector 90, 
and multiplexer 10 constitute a radio receiver. The front-end processor 
120, selector switch 22, intermediate frequency amplifier 8, and detector 
90 constitute a remote-controlled receiver. 
A controller 192 is provided for overall control of the integrated unit 2. 
When receiving a high-level signal from the comparator 16, the controller 
192 allows the radio interface 18 to place the phase detector 90 and 
multiplexer 10 in a driver-selected AM or FM mode and controls tuning of 
the front-end processor 7 according to the drivers choice of a 
broadcasting station. The controller 192 ignores an input signal from the 
detector 90. 
By contrast, when receiving a low-level input from the comparator 16, the 
controller 192 places the detector 90 in either the AM or FM mode 
consistent with a modulation/demodulation form employed with the keyless 
entry system and receives a detection signal from the detector 90 so as to 
decode a remote control signal and control the drive circuit 17 according 
to the remote control signal so that the door lock device 4 is actuated. 
According to the third embodiment of the invention discussed above, when an 
on-vehicle radio set and a keyless entry system use the same intermediate 
frequency and modulation/demodulation form, they can share not only the 
on-vehicle antenna 1 but also the intermediate frequency amplifier 8 and 
phase detector 90 which are included in receiving equipment. This results 
in a reduction in cost. 
FIG. 4 shows an overall configuration of a fourth embodiment of the present 
invention. In the fourth embodiment, the on-vehicle radio set and the 
keyless entry system use the same frequencies and share an on-vehicle 
antenna as well as a front-end processor that is part of receiving 
equipment. The components identical to those in FIG. 1 are assigned the 
same reference numerals. 
A front-end processor 70 whose tuning frequency is variable within a band 
containing a frequency employed in the keyless entry system and a selector 
switch 23 for supplying an output signal of the front-end processor 70 
selectively to the intermediate frequency amplifiers 8 and 13 are 
provided. When the comparator 16 provides a high-level signal, the 
selector switch 23 is switched over to the intermediate frequency 
amplifier 8 so that an intermediate frequency signal relating to a radio 
broadcast is fed to the intermediate frequency amplifier 8. When the 
comparator 16 provides a low-level signal, the selector switch 23 is 
switched over to the intermediate frequency amplifier 13 so that an 
intermediate frequency signal relating to a remote control signal is fed 
to the intermediate frequency amplifier 13. The front-end processor 70, 
selector switch 23, intermediate frequency amplifier 8, detector 9, and 
multiplexer 10 constitute a radio receiver. The front-end processor 12, 
selector switch 23, intermediate frequency amplifier 13, and detector 14 
constitute a remote-controlled receiver. A controller 193 is responsible 
for the overall control of the integrated unit 2. When receiving a 
high-level signal from the comparator 16, the controller 193 ignores a 
detection signal sent from the detector 14, allows the radio interface 18 
to place the detector 9 and multiplexer 10 in a driver-selected AM or FM 
mode, and controls tuning of the front-end processor 70 according to the 
driver's choice of a broadcasting station. 
By contrast, when receiving a low-level signal from the comparator 16, the 
controller 193 tunes the front-end processor 70 so that the frequency of 
the front-end processor 70 matches the frequency employed in the keyless 
entry system. The controller 193 then decodes a remote control signal in 
response to a detection signal sent from the detector 14 and controls the 
drive circuit 17 according to the remote control signal so that the door 
lock device 4 is actuated. 
According to the fourth embodiment of the invention discussed above, when 
the on-vehicle radio set and the keyless entry system employ different 
modulation/demodulation forms and use the same frequencies, they can share 
not only the on-vehicle antenna 1 but also the front-end processor 70. 
This results in a reduction in cost. 
In any of the embodiments discussed above, the input stage of the 
transformer 15 may be the ACC switch instead of the key switch 3. When the 
antenna tuning circuits in the front-end processors 7 and 70 can be placed 
in either the AM or FM mode, mode change for the front-end processors 7 
and 70 may be interlocked with mode change for the phase detectors 9 and 
90. Moreover, even when a vehicle security system is substituted for the 
keyless entry system, or any other on-vehicle remote-controlled system, 
the present invention can still be employed. The radio receiver may also 
be designed to have the ability to receive TV audio broadcasts. 
As discussed above, according to the present invention, it is detected 
whether the ignition key is fitted into the key cylinder. When it is 
detected that the ignition key is fitted into the key cylinder, an 
on-vehicle antenna is switched over to an on-vehicle radio set. When it is 
detected that the ignition key is not fitted into the key cylinder, the 
on-vehicle antenna is switched over to an on vehicle remote-controlled 
receiving system. Thus, a single on-vehicle antenna can be shared by the 
on-vehicle radio set and the on-vehicle remote control receiving system. 
As also discussed above, the on-vehicle remote controlled receiving system 
and on-vehicle radio set can also share part of the receiver equipment. 
When the on-vehicle remote-controlled receiving system and on-vehicle 
radio set share part of receiving equipment cost is reduced. 
This disclosure is illustrative and not limiting; further modifications 
will be apparent to one skilled in the art, and are intended to fall 
within the scope of the appended claims.