Keyless system

In a keyless system including a car-mounted device and a portable device carried by a user, the portable device detects the static state of the portable device for an arbitrarily set time period or longer with a static action detection section, and transmits a response signal serving as a response to a challenge signal transmitted from the car-mounted device on condition that the static state has been detected by the static action detection section. This can allow vehicle control such as locking and unlocking of a door of a vehicle through a simple action not requiring operation with a user's hand, and can prevent unnecessary vehicle control not intended by the user.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a keyless system for performing vehicle control including locking and unlocking of a door of a vehicle, opening and closing of a slide door, and turn-on of an interior light through communication for authentication between a portable device and a car-mounted device.

Description of the Related Art

Conventionally known automobile communication systems for enhancing the convenience of automobiles include a keyless system for allowing vehicle control including locking and unlocking of a door, opening and closing of a slide door, and turn-on of an interior light by a user carrying a portable device and operating a switch provided for a door knob of a vehicle or touching a touch sensor with his finger.

Such a keyless system involves communicating a challenge signal in an LF band and a resulting response signal in a UHF band between a car-mounted device and a portable device carried by a user to identify and authenticate the portable device to process communication data, and achieves enhanced convenience as compared with operation for door opening and closing using a conventional mechanical key or operation of buttons using a wireless key.

In the system as described above, however, in a situation where it is difficult to operate the switch or the touch sensor such as when a user carries baggage in both hands or cannot find the location of a door knob in a dark place, the user cannot enjoy sufficient convenience. This produces the need for a hands-free function which does not require any operation using a user s hand, and various proposals thereof have been made.

Patent Literature 1 has proposed a door lock control apparatus equipped with an automatic lock function of automatically locking a door of a vehicle when a user carrying a portable device moves away from the vehicle to a distance where close-range LF communication is not established or to a distance where medium- to long-range UHF communication is not established. Although the related art is directed only to the locking operation, it is easily conceivable that the related art may be extended to unlocking operation on condition that the user enters the LF communication range of the vehicle and communication is established.

Patent Literature 2 has proposed a slide door opening/closing apparatus provided with a human detection unit for detecting the presence or absence of a user near a vehicle and an action detection unit for detecting a predefined action with a user's foot or the like. The related art eliminates the need for any operation with a user's hand and allows opening and closing of a slide door with fewer erroneous operations even when both hands of the user are full.

CITATION LIST

Patent Literature

When the door lock control apparatus proposed in Patent Literature 1 is extended and applied to the unlock control, however, a problem arises in which communication for authentication is established merely by a user approaching the vehicle to perform the vehicle control even when the user has no intention thereof. In particular, the unintentional unlocking operation leads to a lower level of security and thus needs to be prevented.

Since Patent Literature 1 involves the communication for authentication performed between the portable device and the car-mounted device, the car-mounted device employs a communication sequence in which it always transmits a challenge signal in an LF hand. This results in a problem of fast drain of a battery on the vehicle or a battery on the portable device and a problem of radio interference with the communication between other vehicles.

In the keyless system provided with the slide door opening/closing apparatus presented in Patent Literature 2, the automatic opening and closing of the slide door requires an ultrasonic sensor or an infrared sensor serving as the human detection unit and a motion sensor serving as the action detection unit to be installed at a plurality of points such as close to left and right doors of the vehicle, which leads to a problem of an increased number of parts to cause high cost.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problems, and it is an object thereof to provide a keyless system allowing vehicle control such as locking and unlocking of a door of a vehicle through a simple action not requiring operation with a user's hand, and achieving low cost, reduced power consumption, and enhanced convenience.

According to an aspect, the present invention provides a keyless system including a car-mounted device mounted on a vehicle and a portable device carried by a user, the keyless system configured to perform communication for authentication such that the car-mounted device transmits a challenge signal and the portable device transmits back a response signal thereto, the car-mounted device configured to perform vehicle control including locking and unlocking of a door of the vehicle when the portable device is authenticated in the communication for authentication, wherein the car-mounted device includes a first close-range communication equipment configured to transmit the challenge signal through a signal in an LF band, a first medium- to long-range communication equipment configured to receive a signal in a UHF band transmitted by the portable device, and a first processor configured to authenticate the portable device based on the response signal received by the first medium- to long-range communication equipment, and the portable device includes a second close-range communication equipment configured to receive the challenge signal transmitted by the first close-range communication equipment, a second medium- to long-range communication equipment configured to transmit at least a response signal through a signal in the UHF band, out of the request signal for requesting the challenge signal from the car-mounted device and the response signal serving as a response to the challenge signal, an action detection section configured to sense and convert vibrations or a change of position of the portable device into an electric signal, a static action detection section configured to detect a static state of the portable device for an arbitrarily set time period or longer based on the electric signal output from the action detection section, and a second processor configured to cause the second medium- to long-range communication equipment to transmit the request signal or the response signal on condition that the static state has been detected by the static action detection section within a predetermined time period.

According to another aspect, the present invention provides a keyless system including a car-mounted device mounted on a vehicle, and a portable information terminal and a portable device both carried by a user, the keyless system configured to perform communication for authentication such that the car-mounted device transmits a challenge signal and the portable device transmits back a response signal thereto, the car-mounted device configured to perform vehicle control including locking and unlocking of a door of the vehicle when the portable device is authenticated in the communication for authentication, wherein the car-mounted device includes a first close-range communication equipment configured to transmit the challenge signal through a signal in an LF band, first medium- to long-range communication equipment configured to receive a signal in a UHF band transmitted by the portable device, and a first processor configured to authenticate the portable device based on the response signal received by the first medium- to long-range communication equipment, the portable information terminal includes a first external device interface configured to perform bidirectional communication with the portable device, an acceleration sensor configured to convert an acceleration produced from a change position of the portable information terminal into an electric signal, and a static action detection section configured to detect a static state of the portable information terminal for an arbitrarily set time period or longer based on an acceleration sensor signal output from the acceleration sensor, and the portable device includes a second external device interface configured to perform bidirectional communication with the portable information terminal, a second close-range communication equipment configured to receive the challenge signal transmitted by the first close-range communication equipment, a second medium- to long-range communication equipment configured to transmit at least the response signal through a signal in the UHF band, out of the request signal for requesting the challenge signal from the car-mounted device and the response signal serving as a response to the challenge signal, and a second processor configured to acquire the result of detection by the static action detection section through the first external device interface and the second external device interface, and to cause the second medium- to long-range communication equipment to transmit the request signal or the response signal on condition that the static state has been detected within a predetermined time period.

According to another aspect, the present invention provides a keyless system including a car-mounted device mounted on a vehicle, and a portable information terminal and a portable device both carried by a user, the keyless system configured to perform communication for authentication such that the car-mounted device transmits a challenge signal and the portable information terminal or the portable device transmits back a response signal thereto, the car-mounted device configured to perform vehicle control including locking and unlocking of a door of the vehicle when the portable device is authenticated in the communication for authentication, wherein the car-mounted device includes a first close-range communication equipment configured to transmit the challenge signal through a signal in an LF band, a third external device interface configured to perform bidirectional medium- to long-range communication with at least the portable information terminal out of the portable device and the portable information terminal and to receive at least the response signal out of a request signal and the response signal through a signal for medium- to long-range communication transmitted by the portable device or the portable information terminal, and a first processor configured to authenticate the portable device based on the response signal received by the third external device interface, the portable information terminal includes a first external device interface configured to perform bidirectional communication with the car-mounted device and the portable device, an acceleration sensor configured to convert an acceleration produced from a change of position of the portable information terminal into an electric signal, and a static action detection section configured to detect a static state of the portable information terminal for an arbitrarily set time period or longer based on an acceleration sensor signal output from the acceleration sensor, and the portable device includes a second external device interface configured to perform bidirectional communication with at least the portable information terminal out of the car-mounted device and the portable information terminal, a second close-range communication equipment configured to receive the challenge signal transmitted by the car-mounted device, and a second processor configured to acquire the result of detection by the static action detection section through the first external device interface and the second external device interface, and to cause the second external device interface or the first external device interface to transmit the request signal for requesting the challenge signal from the car-mounted device or the response signal serving as a response to the challenge signal on condition that the static state has been detected within a predetermined time period.

According to the keyless system of the present invention, the communication for authentication is performed on condition that the static state of the portable device has been detected by the static action detecting section of the portable device carried by the user. This can allow vehicle control such as locking and unlocking of the door of the vehicle through a simple action not requiring operation with a user's hand, and can prevent unnecessary vehicle control not intended by the user.

In addition, the portable information terminal for bidirectional communication with the portable device is provided and the static state is detected by the acceleration sensor and the static action detection section included in the portable information terminal, so that, the portable device can be simplified in configuration and reduced in size. Furthermore, since the high-performance acceleration sensor and a fast CPU can be utilized in the portable information terminal, the static action of the user can be detected with high accuracy.

Since each of the car-mounted device, the portable information terminal, and the portable device is provided with the external device interface, the medium- to long-range communication equipment can be omitted in the car-mounted device the portable device to simplify the configuration and reduce the cost. In addition, the portable information terminal or the portable device can estimate the distance from the car-mounted device based on the status of establishment of bidirectional communication with the car-mounted device or the intensity of a received signal therefrom, and can cause transmission of the request signal when the portable information terminal or the portable device is in the medium- to long-range communication establishment area of the car-mounted device and the static action detection section detects the static state. This can reduce the number of transmissions of ineffective challenge signals by the car-mounted device, thereby reducing power consumption and radio interference with the communication between other vehicles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A keyless system according to Embodiment 1 of the present invention will hereinafter be described with reference to the drawings.FIG. 1is a diagram showing a representative layout of the keyless system according to Embodiment 1.FIG. 2is a block diagram showing the configurations of a car-mounted device and a portable device in the keyless system according to Embodiment 1. In the drawings, the identical or corresponding components are designated with the same reference numerals.

The keyless system according to Embodiment 1 of the present invention includes a car-mounted device1mounted on a vehicle100and a portable device2typically carried by a user who is a driver, and performs communication for authentication in which the car-mounted device1transmits a challenge signal and the portable device2transmits back a response signal. When the authentication of the portable device2is performed successfully in the communication for authentication, the car-mounted device1performs vehicle control including locking and unlocking of a door of the vehicle100.

Close-range communication at low frequencies in the LF band is used for the communication from the car-mounted device1to the portable device2. Medium- to long-range communication at high frequencies in the UHF band is used for the communication from the portable device2to the car-mounted device1. When medium- to long-range communication compliant with BLUETOOTH® is used as in Embodiment 2, later described, bidirectional communication is possible between the car-mounted device1and the portable device2.

The vehicle100is equipped with, as antennas for the car-mounted device1, LF antennas14a,14b,14c, and14d(referred to collectively as LF antenna14) for transmitting the challenge signal provided by an LF signal141and a UHF antenna15for receiving at least the response signal out of the response signal and a request signal provided by a UHF signal251transmitted from the portable device2.

The LF antennas14a,14b, and14care installed on knobs of doors or a trunk and form LF communication establishment areas (indicated by dotted lines A, B, and C inFIG. 1) in which the challenge signal can be communicated to the portable device2generally within a range of approximately one meter outside the care. The LF antenna14dforms an LF communication establishment area (indicated by a dotted line U inFIG. 1) in which the LF challenge signal can be communicated to the portable device2throughout the interior of the car.

The UHF communication with the UHF signal251is medium- to long-range communication longer than the LF communication and typically covers several tens to several hundreds of meters. In other words, a UHF communication establishment area (indicated by a dotted line E inFIG. 1) corresponds to a range of several tens to several hundreds of meters from the UHF antenna15for the car-mounted device1. The UHF signal251transmitted from the portable device2within the UHF communication establishment area is received by the UHF antenna15and input to the car-mounted device1.

A switch or an electrostatic sensor (either not shown) is installed for sensing an instruction from a user to start the communication between the car-mounted device1and the portable device2on a door or a door knob outside the car or inside the car close to the LF antenna14. Upon activation of the switch, communication for authentication is started between the car-mounted device1and the portable device2located within the LF communication establishment area outside the car, and when the authentication is successfully performed, vehicle control is performed such as locking or unlocking of a door.

When the switch inside the car is activated to start communication for authentication between the LF antenna14and the portable device2located in the LF communication establishment area D in the vehicle100and the authentication is successfully performed, then vehicle control is performed such as start or stop of an engine. AlthoughFIG. 1shows the LF antenna14for the vehicle100consisting of four antennas, the present invention is not limited thereto, and the number of the antennas can be changed depending on the size of the vehicle100or the layout of the LF antenna14.

As shown inFIG. 2, the car-mounted device1of the keyless system according to Embodiment 1 is configured to include a control section11serving as a first processor, a body control section12, an LF transmission section13and the LF antenna14together serving as a first close-range communication equipment, and the UHF antenna15and a UHF reception section together serving as a first medium- to long-range communication equipment.

The control section11is formed, for example of a CPU responsible for the overall control of the car-mounted device1and authenticates the portable device2based on the response signal received by the UHF antenna15. The body control section12performs the vehicle control such as locking and unlocking of a door, and start and stop of the engine based on a control signal from the control section11.

The LF transmission section13modulates a challenge signal to be transmitted to the portable device2. The LF antenna14transmits the modulated challenge signal corresponding to the LF signal141. The UHF antenna15receives a response signal corresponding to the UHF signal251transmitted from the portable device2. The UHF reception section16demodulates the radio signal.

The portable device2is configured to include a control section21serving as a second processor, an LF antenna22and an LF reception section23together serving as a second close-range communication equipment, a UHF transmission section24and a UHF antenna25together serving as a second medium- to long-range communication equipment, and an action detection section26serving as an action detector, and a static action detection section27serving as a static action detector for detecting a static action of a user carrying the portable device2.

The control section21is formed, for example of a CPU responsible for the overall control of the portable device2. The LF antenna22receives a challenge signal transmitted from the LF antenna14of the car-mounted device1. The LF reception section23demodulates the challenge signal received by the LF antenna22. The UHF transmission section24modulates a response signal serving as a response to the challenge signal. The UHF antenna25transmits the modulated response signal.

In the keyless system according to the present invention, the UHF signal251transmitted from the portable device2to the car-mounted device1includes the request signal for requesting the challenge signal from the car-mounted device1and the response signal serving as the response to the challenge signal. The portable device2according to Embodiment 1 transmits only the response signal.

The action detection section26of the portable device2is configured to include a vibration sensor, an acceleration sensor or the like, and senses and converts any vibrations or change of position of the portable device2into an electric signal. The static action detection section27detects a static state of the portable device2for an arbitrarily set time period or longer based on the electric signal output from the action detection section26. The control section21causes the UHF transmission section24and the UHF antenna25to transmit a response signal on condition that the static state has been detected by the static action detection section27within a predetermined time period.

Next, the configurations of the action detection section26and the static action detection section27of the portable device2are described with reference toFIG. 3toFIG. 6.FIG. 3is a block diagram showing the configurations of the action detection section and the static action detection section of the portable device.FIGS. 4 and 5show exemplary circuit configurations of the action detection section.FIG. 6shows an exemplary circuit configuration of the static action detection section.

As shown inFIG. 3, the action detection section26includes a vibration sensor261having a switch which changes a signal path between a connection state and a disconnection state in response to vibrations of the portable device2and configured to output a vibration sensor signal (switch signal SG1), and an action detection circuit262for converting the switch signal SG1output from the vibration sensor261into an action signal SG2indicating the action state of the portable state2before output of the action signal SG2. The action detection circuit262outputs the action signal in the action state changing between “High” and “Low.”

An action detection circuit262ashown inFIG. 4as an exemplary configuration of the action detection circuit262is formed of a circuit for filtering and outputting the switch signal SG1from the vibration sensor261which is turned ON and OFF by vibrations. An action detection circuit shown inFIG. 5is formed of an edge detection circuit262bfor detecting the leading edge and falling edge of the switch signal SG1from the vibration sensor261.

The action detection circuit26is not limited to one including the vibration sensor261and the action detection circuit262. For example, an acceleration sensor for converting an acceleration produced from changes of position of the portable device2into an electric signal may be used such that the movement of the portable device2is sensed from the amount of change in the value of an acceleration sensor signal and the acceleration sensor signal is converted into an action signal. How to convert the acceleration sensor signal output from the acceleration sensor into the action signal is described in Embodiment 3, later described.

The static action detection section27includes a timer counter271serving as a time measurement unit and a comparator272serving as a comparison unit for determining whether or not a static time period exceeds the arbitrarily preset time period. As shown inFIG. 6, the timer counter271is formed of an asynchronous counter including a plurality of Delay Flip-Flops (DFFs) and has a characteristic of being a circuit of low power consumption.

The timer counter271is enabled by a start signal SG3to start operation, receives input of the action signal SG2output from the action detection section26as a reset signal, and counts pulses of a clock signal SG4to measure time starting from the point when the reset signal is cleared.

The comparator272compares the time measured by the timer counter271, that is, a counter value T, with a static time parameter value Ts corresponding to the arbitrarily set time period, and when the counter value T exceeds the static time parameter value Ts, determines that the exceeding time period corresponds to a static state, and outputs a static state signal SG5indicating whether or not the portable device2is in a static state. The static state signal SG5indicates that the user changes from an active state to a static state or from a static state to an active state.

The comparator272is formed of a reception apparatus for receiving the counter value T provided by the timer counter271and a processing circuit for comparing the arbitrary static time parameter value Ts with the counter value provided by the timer counter271and producing the static state signal SG5based on the comparison result.

The operations of the action detection section26and the static action detection section27of the portable device2according to Embodiment 1 are described with timing waveforms inFIG. 7. InFIG. 7, the horizontal axis represents time. The action detection section26performs filtering with a certain time constant on the vibration sensor signal (switch signal SG1) changing between High and Low in accordance with the movement of the portable device2to produce the action signal SG2.

When the start signal SG3is enabled at a time t1, the static action detection section27starts the count of pulses of the clock signal SG4and updates the counter output. When the portable device2remains in the static state and the counter value T reaches the static time parameter value Ts at a time t2, the counter operation stops, and the static state signal SG5indicating the change from the active state to the static state is output.

When the portable device2is operated to bring the action signal Low at a time t3, the action signal SG2is applied to a rest input of the timer counter271, and thus the counter value T is reset to the initial state. In an example shown byFIG. 7, the time period between the time t2and the time t3, and the time period between a time t5and a time t6are determined to be the static state, during which the static state signal SG5indicating the static state is output.

The control section21of the portable device2refers to the static state signal output from the static action detection section27when the LF antenna22receives the challenge signal, and causes the UHF transmission section24and the UHF antenna25to transmit the response signal only if the static state has been detected within the predetermined time period. The predetermined time period is a short time period of approximately several seconds immediately before the reception of the challenge signal and is preset and stored in the portable device2.

FIG. 8shows a communication sequence performed when a hands-free function is implemented in the keyless system according to Embodiment 1. InFIG. 8, P1to P11indicate positions of the portable device2relative to the vehicle100having the car-mounted device1mounted thereon.FIG. 8represents changes in positional relationship between the user carrying the portable device2and the car-mounted device1and how the communication is performed between the car-mounted device1and the portable device2.FIG. 9shows a flow chart of communication control performed when the hands-free function is used to unlock a door in the keyless system according to Embodiment 1.

The flow of communication control performed when the hands-free function is implemented in the keyless system according to Embodiment 1 is described with reference toFIG. 8andFIG. 9. As a comparative example,FIG. 10andFIG. 11show an exemplary communication sequence and an exemplary flow chart of communication control performed when a hands-free function is implemented on the basis of a conventional scheme. In the flow charts ofFIG. 9andFIG. 11, the same step number represents the same processing.

First, at step S1inFIG. 9, the car-mounted device1intermittently transmits a challenge signal corresponding to a signal in the LF band. At step S2, the portable device2starts detection of a static action. InFIG. 8, when the user stays at any of the positions P1to P4outside the LF communication establishment area, the portable device2does not make any reaction since the challenge signal does not arrive.

At step S3, the portable device2determines whether or not the challenge signal is received from the car-mounted device1. When the challenge signal is received (YES), the portable device2checks whether or not it has detected a static action by the static action detection section27within the predetermined time period at step S4. When it is determined that the static action has been detected at step S4(YES), the portable device2transmits back a response signal at step S5.

InFIG. 8, when the user reaches the position P5or P6in the LF communication establishment area, the portable device2receives the challenge signal from the car-mounted device1. However, the user is not stationary at the position P5or P6but merely passes by, so that it is determined that any static action is not detected at step S4(NO), and the portable device2does not transmit back a response signal. When the user enters the LF communication establishment area again to reach the position P9and then is stationary at the position P10, it is determined that the static action is detected at step S4(YES), and the portable device2transmits back a response signal at step S5.

Subsequently at step S6, the car-mounted device1authenticates the portable device2based on the response signal transmitted from the portable device2, and when the authentication is successfully performed (YES), unlocks the door of the vehicle100at step S7and completes the hands-free function. When the portable device2does not receive the challenge signal from the car-mounted device1at step S3(NO) when the portable device2does not detect the static action at step S4(NO), and when the authentication is not successfully performed at step S6(NO), the control returns to step S3to repeat the processing described above.

As described above, the keyless system according to Embodiment 1 establishes the communication for authentication only when the user performs the static action with the intention of riding into the vehicle100. In other words, the static state signal output from the static action detection section27of the portable device2indicating the static state is a precondition for the establishment of the communication for authentication.

In contrast, in the conventional scheme shown byFIG. 10, when a user carrying the portable device2stays at any of the positions P1to P4outside the LF communication establishment area, the portable device2does not make any reaction since a challenge signal does not arrive. However, when the user reaches a position P5within the LF communication establishment area, the portable device2determines that the challenge signal is received from the car-mounted device1at step S3inFIG. 11, and transmits back a response signal at step S5. When authentication is successfully performed at step S6, the door of the vehicle100is unlocked at step S7.

In the example shown byFIG. 10, the user does not perform any static action when he reaches the position P5within the LF communication establishment area, but the portable device2transmits back the response signal. As a result, communication for authentication is established at the position P5and the door is unlocked. However, the user only approaches the vehicle100and does not ride. At the position P8outside the LF communication establishment area, the communication for authentication is disabled and the door is locked.

As described above, in the conventional scheme, when the user does not intend to ride into the vehicle100or moves away from the vehicle100without riding, unnecessary door control is performed such as the unlocking of the door of the vehicle100when the user enters the LF communication establishment area.

As described above, according to the keyless system of Embodiment 1, the static action detection section27of the portable device2carried by the user detects the static state of the portable device2for the arbitrarily set time period or longer, and the response signal is transmitted on condition that the static action detection section27detects the static state. This can realize the hands-free function such as the locking and unlocking of the door of the vehicle100through the simple action not requiring action with a user's hand.

Since the natural behavior of the user, that is, the static action, is used, and the time period of the static action can be set arbitrarily, the hands-free function can be realized as appropriate for each user without discomfort. In addition, unnecessary vehicle control not intended by the user can be prevented to reduce the load on a battery for the vehicle100and therefore the power consumption.

Some conventional systems include an ultrasonic sensor or an infrared sensor serving as the human detection unit and a motion sensor serving as the action detection unit provided at a plurality of points close to doors of a vehicle. As compared with such conventional systems, the keyless system according to Embodiment 1 realizes a simplified structure with a reduced number of parts and a lower cost. From the above, according to Embodiment 1, the keyless system can be provided with low cost, reduced power consumption, and enhanced convenience.

FIG. 12is a block diagram showing the configurations of a car-mounted device and a portable device in a keyless system according to Embodiment 2 of the present invention. A car-mounted device1A of the keyless system according to Embodiment 2 is configured such that the UHF reception section16in the car-mounted device1(seeFIG. 2) according to Embodiment 1 is replaced by a BLUETOOTH®-compatible communication section17compliant with the BLUETOOTH® standard, and a first medium- to long-range communication equipment is formed of the BLUETOOTH®-compatible communication section17and the UHF antenna15.

A portable device2A is configured such that the UHF transmission section24in the portable device2according to Embodiment 1 is replaced by a BLUETOOTH®-compatible communication section28, and a second medium- to long-range communication equipment is formed of the BLUETOOTH®-compatible communication section28and the UHF antenna25. Since the other configurations are similar to those in Embodiment 1, description thereof is omitted.

Similarly to Embodiment 1, the keyless system according to Embodiment 2 can implement a hands-free function by using the communication sequence shown inFIG. 8and the communication control flow chart shown inFIG. 9. Specifically, the control section21of the portable device2A can cause the UHF antenna25to transmit a response signal on condition that the static action detection section27detects a static state.

In addition, medium- to long-range communication between the car-mounted device1A and the portable device2A is provided through the BLUETOOTH® communication capable of bidirectional communication in Embodiment 2, an approximate distance between the portable device2A and the car-mounted device1A can be detected on the basis of the status of establishment of bidirectional communication or the intensity of a received signal.

The control section21of the portable device2A may estimate the distance between the portable device2A and the car-mounted device1A based on the status of establishment of bidirectional communication with the medium- to long-range communication equipment of the car-mounted device1A or the intensity of a received signal therefrom, and may cause the UHF antenna25to transmit a request signal when the portable device2A is in the medium- to long-range communication establishment area of the car-mounted device1A and the static action detection section27detects a static state.

According to Embodiment 2, in addition to the similar advantages to those in Embodiment 1, the distance relationship between the car-mounted device1A and the portable device2A can be added to the condition for detecting the static action, and the request signal can be transmitted when the portable device2A is in the medium- to long-range communication establishment area of the car-mounted device1A, so that this request signal serves as a trigger for communication for authentication. This can reduce the number of transmissions of ineffective challenge signals, thereby reducing power consumption and radio interference with the communication between other vehicles.

Since the standard BLUETOOTH® communication is employed for the medium- to long-range communication, development cost can be reduced to realize the keyless system at a lower cost. In addition, Embodiment 2 can provide the advantage of facilitating an interface with other portable information terminals represented by smartphones.

FIG. 13is a block diagram showing the configurations car-mounted device, u portable device, and a portable information terminal in a keyless system according to Embodiment 3 of the present invention. The keyless system according to Embodiment 3 is configured to include a car-mounted device1, a portable device2B, and a portable information terminal3. Since the configuration of the car-mounted device1according to Embodiment 3 is similar to that of the car-mounted device1(seeFIG. 2) according to Embodiment 1, description thereof is omitted.

The portable device273according to Embodiment 3 differs from the portable device2(seeFIG. 2) according to Embodiment 1 in that it is configured to include an external device interface29serving as a second external device interface and not to include the action detection section26and the static action detection section27. Since the other configurations are similar to those of the portable device2according to Embodiment 1, description thereof is omitted.

The portable information terminal3includes an external device interface31serving as a first external device interface for performing bidirectional communication with the external device interface29of the portable device2A, an acceleration sensor32, and a static action detection section33serving as a static action detector. The acceleration sensor32converts an acceleration produced from changes of position of the portable information terminal3into an electric signal. The static action detection section33detects a static state of the portable information terminal3for an arbitrarily set time period or longer based on an acceleration sensor signal output from the acceleration sensor32.

The external device interface31of the portable information terminal3and the external device interface29of the portable device2B perform communication according to the BLUETOOTH® standard. The portable information terminal3is formed of a smartphone or a tablet which functionally corresponds to a smartphone and is not limited to any particular device.

As shown inFIG. 14, the acceleration sensor32is a three-axis acceleration sensor for detecting an X-axis acceleration32x, a Y-axils acceleration32y, and a Z-axis acceleration32zorthogonal to each other. The acceleration of gravity is detected as three-axis components of X, Y, and Z depending on any inclination of the portable information terminal3.

As shown inFIG. 15, the static action detection section33of the portable information terminal3includes an action detection section331serving as an action detection unit, a timer counter332, and a comparator333. The action detection section331samples a three-axis acceleration sensor signal SG6of three-axis directions orthogonal to each other output from the acceleration sensor32and senses and converts the movement of the portable information terminal3from the amount of change in the sampled signal value into an action signal SG7.

The timer counter332serving as a time measurement unit starts processing upon instruction of a start signal SG3, measures time by using the action signal SG7output from the action detection section331as a reset signal, and outputs a counter value T. The comparator333compares the counter value T measured by the timer counter332with a static time parameter value Ts corresponding to the arbitrarily set time period, and when the counter value T exceeds the static time parameter value Ts, determines that the exceeding time corresponds to a static state, and outputs a static state signal SG5indicating whether or not the portable information terminal3is in a static state.

The operations of the acceleration sensor32and the static action detection section33of the portable information terminal3according to Embodiment 3 are described with reference to timing waveforms inFIG. 16. InFIG. 16, the horizontal axis represents time. The acceleration sensor32outputs accelerations in the X-axis, Y-axis, and Z-axis directions as digital values (three-axis acceleration sensor signal SG6).

The action detection section331receives the input of the acceleration values in the respective axes and calculates a difference in terms of a sampling time n (n=0, 1, 2, 3, . . . ) according to the following expressions 1 to 3. The difference value, that is, the acceleration change amount is calculated to detect the magnitude of movement of the portable information terminal3.
ΔX(n)=X(n+1)−X(n)  (Expression 1)
ΔY(n)=Y(n+1)−Y(n)  (Expression 2)
ΔZ(n)=Z(n+1)−Z(n)  (Expression 3)

The acceleration sensor32mounted on the portable information terminal3has high accuracy and outputs a change amount even from small vibrations. When the user carries the portable information terminal3, it is often difficult to maintain the terminal3in a completely static state. Thus, as shown inFIG. 16, the action detection section331sets a movement determination threshold value Lim, and determines that any movement occurs in each axis direction when the Lim is exceeded.

The action detection section331outputs the action signal SG7when any movement occurs in any of the X axis, Y axis, or Z axis. Specifically, the action signal SG7is “High” if at least one of |ΔX(n)|>Lim, |ΔY(n)|>Lim, or |ΔZ(n)|>Lim is satisfied, or “Low” if not.

Since the action signal SG7is input as the rest signal to the timer counter332, the counter value T is reset and returns to the initial state when the portable information terminal3moves and any pulse is output in the action signal SG7. In the example shown byFIG. 16, when the portable information terminal3remains in the static state and the counter value T reaches the static time parameter value Ts at a time t2, the counter operation stops, and the static state signal SG5indicating the static state is output.

When any pulse is output in the action signal SG7at a time t3, the counter value T is reset and returns to the initial state. En the example shown byFIG. 16, the time period between the time t2and the time t3, and the time period between a time t5and a time t6are determined to be the static state, during which the static state signal SG5indicating the static state is output.

Since the communication sequence and the communication control flow chart performed when the hands-free function is implemented in the keyless system according to Embodiment 3 are similar to those in Embodiment 1, description thereof is omitted (seeFIG. 8andFIG. 9). In Embodiment 3, however, the static action detection section33of the portable information terminal33determines the static action at step S4in the flow chart ofFIG. 9.

According to Embodiment 3, in addition to the similar advantages to those in Embodiment 1, the portable device2B and the portable information terminal3such as a smartphone are connected to each other through the external device interfaces29and31, and the portable information terminal3is provided with the acceleration sensor32and the static action detection section33for detecting the static action of the user, so that the portable device2E can be simplified in configuration and reduced in size. Since the high-performance acceleration sensor32and a fast CPU can be utilized in the portable information terminal3, the static action of the user can be detected with high accuracy.

FIG. 17is a block diagram showing the configurations of a car-mounted device, a portable device, and a portable information terminal in a keyless system according to Embodiment 4 of the present invention. A car-mounted device is in the keyless system according to Embodiment 4 includes, in addition to the configuration similar to that of the car-mounted device1(seeFIG. 13) according to Embodiment 3, an external device interface18serving as a third external device interface for performing medium- to long-range bidirectional communication with the portable information terminal3.

Since the configurations of the portable device2B and the portable information terminal3according to Embodiment 4 are similar to those of the portable device2B and the portable information terminal3(seeFIG. 13) according to Embodiment 3, and how to detect the static action of the user is similar to that in Embodiment 3, description thereof is omitted.

The external device interface31of the portable information terminal3performs bidirectional communication with the car-mounted device1B and the portable device2B through the external device interface18of the car-mounted device1B and the external device interface29of the portable device2B, respectively. The external device interfaces18,29, and31of the car-mounted device1B, the portable device2B, and the portable information terminal3are interfaces for performing medium- to long-range communication according to the BLUETOOTH® standard.

In Embodiment 4, an approximate distance between the car-mounted device1B and the portable information terminal3can be detected on the basis of the status of establishment of bidirectional communication between the external device interface18of the car-mounted device1B and the external device interface31of the portable information terminal3or the intensity of a received signal. Thus, the general distance relationship between the car-mounted device1B and the portable device2B can be added to the condition for detecting the static action.

Specifically, the control section21of the portable device2B estimates the distance between the portable information terminal3and the car-mounted device1B based on the status of establishment of bidirectional communication between the external device interface31of the portable information terminal3and the external device interface18of the car-mounted device1B or the intensity of a received signal, and causes the UHF antenna25to transmit a request signal when the portable information terminal3is in the medium- to long-range communication establishment area of the car-mounted device1B and the static action detection section33detects a static state.

FIG. 18shows a communication sequence performed when the hands-free function is implemented in the keyless system according to Embodiment 4. InFIG. 18, P1to P7indicate positions of the portable device2B and the portable information terminal3relative to the vehicle100having the car-mounted device1B mounted thereon.FIG. 18represents changes in positional relationship between the user carrying the portable device2B and the car-mounted device1B and how the communication is performed between the car-mounted device and the portable device2B and between the car-mounted device1B and the portable information terminal3.FIG. 19shows a flow chart of communication control performed when the hands-free function is used to unlock a door in the keyless system according to Embodiment 4.

The flow of communication control performed when the hands-free function is implemented in the keyless system according to Embodiment 4 is described with reference toFIG. 18andFIG. 19. When the hands-free function is started, at step S11ofFIG. 19, the portable device2B starts detection of a static action. At this point, the car-mounted device1B does not perform intermittent transmission of a challenge signal. When the user stays at the position P1or P2outside the UHF communication establishment area, the portable device2B performs no operation regardless of the presence or absence of the static action of the user.

Subsequently at step S12, it is checked whether or not the portable device2B is within the medium- to long-range communication area of the car-mounted device1B. When it is within the medium- to long-range communication area (YES), the control proceeds to step S13and the car-mounted device1B controls turn-on of a light such as an interior light of the vehicle100. Communication for authentication is not established in this case, and the control details such as the turn-on of the light at step S13are arbitrarily set. InFIG. 18, when the user approaches the vehicle100and reaches the position P3within the UHF communication establishment area, it is determined that the portable device2B is within the medium- to long-range communication area.

Subsequently at step S14, the portable device2B determines from a static state signal output from the static action detection section33of the portable information terminal3whether or not a static action of the user is detected. When the portable device2B detects the static state at step S14(YES), the control proceeds to step S15and the portable device2B transmits a request signal for requesting start of authentication through a signal in the UHF band.

Upon reception of the request signal, the car-mounted device1B transmits a challenge signal through a signal in the LF band to the portable device2B at step S16. Subsequently at step S17, when the portable device2B is within the LF communication establishment area and receives the challenge signal (YES), the portable device2B transmits back a response signal through a signal in the UHF band at step S18.

Subsequently at step S19, the car-mounted device1B authenticates the portable device2B based on the response signal transmitted from the portable device2B, and when the authentication is successfully performed (YES), unlocks a door of the vehicle100at step S20and ends the hands-free function.

When the portable device2B does not detect the static action at step S14(NO), when the portable device2B does not receive the challenge signal from the car-mounted device1B at step S17(NO), and when the authentication is not successfully performed at step S19(NO), the control returns to step S14to repeat the processing described above.

InFIG. 18, since the user performs the static action at the position P3within the UHF communication establishment area and outside the LF communication establishment area, the portable device2B detects the static action with the static action detection section33of the portable information terminal3and transmits a request signal. Upon reception of the request signal, the car-mounted device1B transmits a challenge signal, but the portable device2B cannot receive the challenge signal since it is outside the LF communication establishment area, and thus the authentication is not successfully performed.

When the user further approaches the vehicle100and performs the static action at the position P5within the LF communication establishment area, the portable device2B detects the static action and transmits a request signal. Then, the portable device2B receives a challenge signal transmitted by the car-mounted device1B and transmits back a response signal to perform authentication. When the authentication is successfully performed, the door of the vehicle100unlocked.

As described above, in the keyless system according to Embodiment 4, when the portable device2B is within the medium- to long-range communication area of the car-mounted device1B and detects the static action of the user, the portable device2B transmits the request signal for requesting the challenge signal to the car-mounted device1B, and this request signal serves as a trigger for communication for authentication.

According to Embodiment 4, in addition to the advantages similar to those in Embodiment 3, the car-mounted device1B does not need to intermittently transmit the challenge signal at all times, and thus the number of transmissions of ineffective challenge signals can be reduced. This can reduce power consumption and radio interference with the communication between other vehicles. Furthermore, since the external device interfaces18,29, and31perform the standard BLUETOOTH® communication, development cost can be reduced to realize the keyless system at a lower cost.

FIG. 20is a block diagram showing the configurations of a car-mounted device, a portable device, and a portable information terminal in a keyless system according to Embodiment 5 of the present invention. Although Embodiments 1 to 4 involve the UHF communication performed for the medium- to long-range communication between the car-mounted device1,1A, or1B and the portable device2,2A, or2B, a car-mounted device1C of the keyless system according to Embodiment 5 performs medium- to long-range communication with the external device interface31of the portable information terminal3through the external device interface18.

The car-mounted device1C according to Embodiment 5 has the configuration in which the UHF antenna15and the UHF reception section17are omitted from the car-mounted device15(seeFIG. 17) according to Embodiment 4. The external device interface18of the car-mounted device1C performs bidirectional medium- to long-range communication with at least the external device interface31of the portable information terminal3out of the portable information terminal3and the portable device2C and receives at least a response signal out of the response signal and a request signal through a medium- to long-range communication signal transmitted from the external device interface29of the portable device2C and the external device interface31of the portable information terminal3.

The portable device2C has the configuration in which the UHF transmission section24and the UHF antenna25are omitted from the portable device2B according to Embodiment 4. The external device interface29of the portable device2C performs bidirectional communication with at least the external device interface31of the portable information terminal3out of the portable information terminal3and the car-mounted device1C. The external device interfaces18,29, and31of the car-mounted device1C, the portable device2C, and the portable information terminal3perform communication according to the BLUETOOTH® standard, but the communication scheme is not particularly limited.

In the keyless system according to Embodiment 5, the portable device2C does not include the UHF transmission section24and the UHF antenna25, the portable information terminal3may perform communication for authentication with the car-mounted device1C. Specifically, the external device interface of the portable information terminal3may transmit a request signal for requesting a challenge signal from the car-mounted device1C and a response signal serving as a response to the challenge signal.

The control section21of the portable device2C acquires the result of detection by the static action detection section33of the portable information terminal3through the external device interfaces29and31, and causes the external device interface29or31to transmit a request signal or a response signal on condition that a static state is detected within a predetermined time period.

Since how to detect the static action of the user in the portable information terminal3is similar to that in Embodiment 3, description thereof is omitted (seeFIG. 16). The communication sequence and the communication control flow chart performed when the hands-free function is implemented in Embodiment 5 are almost similar to those in Embodiment 4 (seeFIG. 18andFIG. 19).

In Embodiment 5, however, the control section21of the portable device2C estimates the distance between the portable information terminal3or the portable device2C and the car-mounted device1C based on the status of establishment of bidirectional communication between the external device interface31of the portable information terminal3or the external device interface29of the portable device2C and the external device interface18of the car-mounted device1C or the intensity of a received signal therefrom. Since both the portable information terminal3and the portable device2C are carried by the user, the distance between the portable information terminal3and the car-mounted device1C is considered as being the same as the distance between the portable device2C and the car-mounted device1C.

According to Embodiment 5, the similar advantages to those in Embodiment 4 can be provided, and the external device interfaces18and29are used as the medium- to long-range communication unit in the car-mounted device1C and the portable device2C to omit the UHF communication sections, so that the configurations of the car-mounted device1C and the portable device2C are simplified to reduce the cost. It should be noted that the embodiments may be combined freely or modified or omitted as appropriate without departing from the spirit or scope of the present invention.