STEERING DEVICE

In order to make it possible to definitively restrict operation of an in-vehicle device by a passenger who is driving a vehicle, by using a simple and economic configuration, a steering device is equipped with a steering wheel and a detection mechanism. The detection mechanism has a first contact sensor that detects contact with the left hand of a driver, and is provided on the side near the in-vehicle device, and also has a second contact sensor that detects contact with the right hand, and is provided on the side away from the in-vehicle device. The detection range of the first contact sensor is set as a narrower region than that of the detection range of the second contact sensor.

TECHNICAL FIELD

The present invention relates to a steering device equipped with a steering wheel, and a detection mechanism adapted to detect contact of the hands of a vehicle occupant over a predetermined region on the circumference of the steering wheel.

BACKGROUND ART

In recent years, various systems have been adopted in automobiles in order to discriminate whether or not the hands of a driver are grasping the steering wheel. For example, a vehicle attention arousing system for a vehicle is known, as disclosed in Japanese Laid-Open Patent Publication No. 2008-059459.

In such a vehicle attention arousing system, a plurality of contact sensors (wires or the like) are arranged over the entire circumference of the steering wheel (paragraph [0054]). In addition, the contact sensors are insulated via insulating bodies at a 12 o'clock position and a 6 o'clock position, and contact with an L (left) side and an R (right) side of the steering wheel is partitioned and detected by an L-side contact detection means and an R-side contact detection means.

Thus, for example, in a state in which contact is detected on both the L-side and the R-side, or stated otherwise, in a state in which it is presumed that the driver is grasping the steering wheel with both hands, there are cases in which the above-described vehicle attention arousing system is applied to a system that allows vehicle-mounted devices to be operated even while traveling.

At such a time, in the vehicle attention arousing system, spaces between the L-side contact detection means and the R-side contact detection means, which are insulated via the insulating bodies, is narrow. In addition, boundaries between the L-side and R-side detection regions are positioned on a vertical center line of the steering wheel in an upright position of the steering wheel (a position in which the vehicle travels straight ahead). Therefore, in the case that the driver grasps the boundary that is positioned at 12 o'clock with one hand (one of the hands), there is a concern that it will be recognized erroneously that the steering wheel is being grasped with both hands, and the driver is made capable of operating the vehicle-mounted device with the other hand.

SUMMARY OF INVENTION

The present invention has been devised in order to solve this type of problem, and has the object of providing, with a simple and economical structure, a steering device which is capable of reliably restricting operations of a vehicle-mounted device by a vehicle occupant while the vehicle is being driven.

The present invention relates to a steering device equipped with a steering wheel, and a detection mechanism configured to detect contact by hands of a vehicle occupant over a predetermined region on a circumference of the steering wheel.

The detection mechanism includes a first contact sensor provided on a side proximate to a vehicle-mounted device as viewed from a front of the steering wheel, and configured to detect contact by one hand of the vehicle occupant. The detection mechanism further includes a second contact sensor provided on a side remote from the vehicle-mounted device, and configured to detect contact by another hand of the vehicle occupant. In addition, a first detection range detected by the first contact sensor is set to a region that is narrower than a second detection range detected by the second contact sensor.

Further, on an upper half of the steering wheel, a boundary between the first detection range and the second detection range may preferably be disposed on a side proximate to the vehicle-mounted device with respect to a vertical center line of the steering wheel.

Furthermore, on a lower half of the steering wheel, a boundary between the first detection range and the second detection range may preferably be disposed on a side proximate to the vehicle-mounted device with respect to a vertical center line of the steering wheel.

Further still, preferably, leather members by which the predetermined region is divided in plurality along the circumference may be wound around the steering wheel. At that time, a conductive paint may preferably be applied to each of the leather members, thereby constituting a first touch sensor and a second touch sensor as the first contact sensor and the second contact sensor, respectively.

According to the present invention, the first detection range that detects one hand of the vehicle occupant (driver) is disposed on the side proximate to the vehicle-mounted device, and is set to a region that is narrower than the second detection range that detects the other hand of the vehicle occupant. Accordingly, at least one of the boundaries between the first contact sensor and the second contact sensor is arranged at a position proximate to the vehicle-mounted device, and at a position that can be easily grasped by one hand of the vehicle occupant.

Therefore, in spite of a state in which only one hand of the vehicle occupant is grasping the boundary between the first contact sensor and the second contact sensor, even in the case it is presumed by the detection mechanism that both hands of the vehicle occupant are in contact with the steering wheel, since the boundary is grasped by the one hand on the side proximate to the vehicle-mounted device, it is difficult for the vehicle-mounted device to be operated with the other hand.

Accordingly, with a simple and economical structure, even if the detection mechanism determines erroneously that the driver is grasping the steering wheel with both hands, and the operation of the vehicle-mounted device is enabled during traveling, it is possible to reliably prevent operation of the vehicle-mounted device.

DESCRIPTION OF EMBODIMENTS

As shown inFIGS. 1 and 2, a steering device10according to an embodiment of the present invention is installed in a vehicle12such as an automobile or the like.

The steering device10is equipped with a steering wheel14, which is an operating member for manipulating a direction in which the vehicle12travels, and a detection mechanism18that detects contact by both hands (a right hand16R and a left hand16L) of a driver H over a predetermined region on the circumference of the steering wheel14.

A contact determining ECU (Electronic Control Unit)20is electrically connected to the steering wheel14, and an operation permission determining ECU22is electrically connected to both the steering wheel14and the contact determining ECU20.

A well-known type of computer is applied to the contact determining ECU20and the operation permission determining ECU22. The contact determining ECU20and the operation permission determining ECU22include a computation unit, a storage unit, an input/output unit, and a counter/timer, etc., none of which are shown. By the computation unit executing programs stored in the storage unit, various function realizing units are constructed, which are needed in order to carry out the contact determination and the operation permission determination, respectively. The function realizing units can also be constituted in the form of hardware.

The vehicle12is equipped with a vehicle-mounted device24such as a navigation device, an air conditioning device, an audio device, or the like, which is not concerned with the basic performance (traveling, turning, stopping) of the vehicle12, and which can be operated by the vehicle occupants (a driver and a fellow passenger).

As shown inFIG. 3, an input device26such as a touch panel, a switch, a volume knob, or the like of the vehicle-mounted device24is disposed in the vicinity of a substantially central portion of a dashboard30of the vehicle12. The steering wheel14, for example, is a right-hand steering wheel, and the vehicle-mounted device24is arranged on one side (the left side inFIG. 3) of the steering wheel14when the vehicle12is observed in plan view. A front door32faces toward another side (the right side) of the steering wheel14.

The steering wheel14is manipulated by the driver H. The input device26of the vehicle-mounted device24is capable of being operated not only by the driver H but also by the fellow passenger. The operation permission determining ECU22is provided in order to restrict the driver H from operating the vehicle-mounted device24while the vehicle12is traveling.

As shown inFIGS. 1 and 2, the steering wheel14is formed in an annular shape, and includes a rim portion34for the driver H to grasp with the right hand16R and the left hand16L. In an upright position of the steering wheel14(a position in which the vehicle12travels straight ahead), radial inner sides of left and right and lower parts of the rim portion34and the steering shaft are connected by a T-shaped connecting part36.

The rim portion34is configured in the form of a laminated structure the cross section of which is made up from a plurality of layers. More specifically, the rim portion34comprises, in order toward a side in a radial outward direction from a cross-sectional center portion thereof, an annular metal core (not shown), a molded layer (not shown) made of a resin material, and a plurality of (for example, two or four) leather layers38L,38R. The core constitutes the skeletal structure of the rim portion34, and is connected to the steering shaft via a connecting member provided inside the connecting part36.

The leather layers38L,38R are wound around the outer circumference of the molded layer with a plurality of leather members being adjacent to each other, respectively, so that the leather members are wound over a predetermined region on the entire circumference of the steering wheel. A first contact sensor (first touch sensor)18L and a second contact sensor (second touch sensor)18R are constituted by applying a conductive paint to each of the leather members. The first contact sensor18L and the second contact sensor18R constitute the detection mechanism18.

As shown inFIG. 3, the first contact sensor18L is provided on a side proximate to the vehicle-mounted device24as viewed from the front of the steering wheel14, and detects contact by the left hand (one hand)16L of the driver H. The second contact sensor18R is provided on a side remote from the vehicle-mounted device24as viewed from the front of the steering wheel14, and detects contact by the right hand (other hand)16R of the driver H.

As shown inFIG. 4, a first detection range40L detected by the first contact sensor18L is set to a region that is narrower than a second detection range40R detected by the second contact sensor18R. The first detection range40L lies within a range that includes a vertical region41L corresponding to a 9 o'clock position of the steering wheel14(a boundary site with a left end portion of the connecting part36). The second detection range40R lies within a range that includes a vertical region41R corresponding to a 3 o'clock position of the steering wheel14(a boundary site with a right end portion of the connecting part36).

On an upper half of the steering wheel14, an upper boundary42abetween the first detection range40L and the second detection range40R is disposed on a side proximate to the vehicle-mounted device24with respect to a vertical center line V of the steering wheel14. The first detection range40L and the second detection range40R lie adjacent to each other, and the upper boundary42ais separated by a space S1, which is of a degree so that the driver H is capable of contacting the first detection range40L and the second detection range40R at the same time with one hand (left hand16L). For example, the space S1of the upper boundary42ais set to a dimension that is less than a width T (seeFIG. 4) of a first of the left hand16L of the driver H (S1<T).

On a lower half of the steering wheel14, a lower boundary42bbetween the first detection range40L and the second detection range40R is disposed on the side proximate to the vehicle-mounted device24with respect to the vertical center line V of the steering wheel14. The lower boundary42bis separated by a space S2, which is of a degree so that the driver H is incapable of contacting the first detection range40L and the second detection range40R at the same time with one hand (the left hand16L or the right hand16R). For example, the space S2of the lower boundary42bis preferably set to a dimension that is greater than the width T of a first of the left hand16L of the driver H (S2>T).

An insulation treatment is implemented on the upper boundary42aand the lower boundary42bin order to electrically isolate the first detection range40L and the second detection range40R. The insulation treatment is carried out, for example, by providing portions on the leather layers38L,38R to which the conductive coating is not applied, or by applying insulating members (insulating materials) on the leather layers38L,38R. Alternatively, the insulating treatment is performed by interposing insulating members between the leather layers38L,38R.

An electrostatic capacitance sensor, which is capable of detecting an electrostatic capacitance in the case that the driver H (human body) has grasped and contacted the steering wheel14, and an electrostatic capacitance in the case that the driver H (human body) is not in contact with the steering wheel14, is used as each of the first contact sensor18L and the second contact sensor18R.

As shown inFIG. 2, a contact signal S1and a contact signal Sr, which are output from the first contact sensor18L and the second contact sensor18R, are supplied respectively to an oscillation circuit44L and an oscillation circuit44R in the contact determining ECU20. Outputs from the oscillation circuit44L and the oscillation circuit44R are connected to a frequency detector (oscillation frequency detector)46L and a frequency detector46R.

An oscillation frequency fl pertaining to the first contact sensor18L for the left hand as detected by the frequency detector46L, and an oscillation frequency fr pertaining to the second contact sensor18R for the right hand as detected by the frequency detector46R are supplied respectively to two input ports of a contact determining unit48. Each of the oscillation circuits44L,44R includes an oscillator main body50, and a resonant circuit including an electrostatic capacitance C and an inductance L.

As shown in the following equations (1) and (2), the frequency detectors46L,46R, which are frequency counters, separately detect an oscillation frequency f, which is a resonant frequency (electrostatic capacitance C) when the driver H is not touching the detection mechanism18with the left hand16L and the right hand16R, and an oscillation frequency f′, which is a resonant frequency when the electrostatic capacitance (C+C′) has increased when the detection mechanism18is touched.

In equations (1) and (2), the electrostatic capacitance C′ is an electrostatic capacitance of the driver (human body) H.

The frequency detector46L detects the oscillation frequency fl when the left hand16L has contacted the first contact sensor18L as the oscillation frequency f′, and detects the oscillation frequency fl at a time of non-contact as the oscillation frequency f.

The frequency detector46R detects the oscillation frequency fr when the right hand16R has contacted the second contact sensor18R as the oscillation frequency f′, and detects the oscillation frequency fr at a time of non-contact as the oscillation frequency f.

For example, in the case that the LC resonant frequency is set to several hundred kHz or the like, a frequency difference (f>>f′) of several tens of kHz is obtained by the contact and non-contact states, and it is possible to sufficiently distinguish between the contact and non-contact states.

The contact determining unit48detects the contact and non-contact states of the left hand16L and the right hand16R to the first contact sensor18L and the second contact sensor18R, from the oscillation frequency fr (non-contact: f, contact: f′) and the oscillation frequency fl (non-contact: f, contact: f′) supplied to the respective input ports, and outputs the detection result as a contact determination output Dt.

The contact determination output Dt is supplied to the input port of an operation permission determining unit52that constitutes the operation permission determining ECU22. A gate signal Gs, which is an output from the operation permission determining unit52, is input to a control port which is one input port of a gate circuit54. An input signal Din, which is an operation input by the driver H to the input device26that makes up the vehicle-mounted device24, is supplied to a signal input port which is another input port of the gate circuit54.

When an “H level” (permission granted) of the gate signal Gs, which is an output of the operation permission determining unit52, is input to the control port, the gate circuit54passes through and outputs the input signal Din that is input to the signal input port. On the other hand, when an “L level” (permission not granted) of the gate signal Gs, which is an output of the operation permission determining unit52, is input to the control port, the gate circuit54interrupts the input signal Din that is input to the signal input port.

The output of the gate circuit54is supplied to an output device28including a main body portion and a display unit of the vehicle-mounted device24. A warning signal (notification signal) Swarn is output from the operation permission determining unit52to an output device56(a display device and a speaker) of a display audio device or the like. The output device56functions as a warning device (notification device).

An FET (field effect transistor)58a, which is connected across the upper boundary42ato the first contact sensor18L and the second contact sensor18R, is connected to the steering wheel14. An FET58b, which is connected across the lower boundary42bto the first contact sensor18L and the second contact sensor18R, is connected to the steering wheel14. The FETs58a,58bare connected to a disconnection detector60, and detect disconnections of the first contact sensor18L and the second contact sensor18R.

Operations of the steering device10, which is configured in the foregoing manner, will be described with reference to the flowchart ofFIG. 5.

In step S1, the contact determining ECU20and the operation permission determining ECU22detect that a non-illustrated power switch (ignition switch) of the vehicle12has been placed in an ON state (YES in step S1).

Next, proceeding to step S2, the operation permission determining unit52detects from the frequency detectors46L,46R the oscillation frequency fl and the oscillation frequency fr of the first contact sensor18L and the second contact sensor18R.

In step S3, the contact determining unit48refers to the oscillation frequencies f, f′ of the oscillation frequency fl and the oscillation frequency fr {the above-described equation (1) and equation (2)}, and performs a contact determination with respect to the first contact sensor18L of the left hand16L, and a contact determination with respect to the second contact sensor18R of the right hand16R.

More specifically, contact determinations are carried out on the basis of the following map (contact determination map), in which a one-hand contact determination or a two-hand contact determination made with respect to the detection mechanism18(first contact sensor18L and second contact sensor18R) is expressed using combinations of the oscillation frequencies [fl, fr].

In the above-described contact determination map, determinations are made that the left hand16L is in contact with the steering wheel14in the third, fourth, and fifth modes from the top.

In the fifth mode, as shown inFIG. 6, the left hand16L of the driver H is in a state of simultaneous contact with the first contact sensor18L and the second contact sensor18R while straddling across the upper boundary42a. At such a time, the right hand16R may not be in contact with the second contact sensor18R.

When it is determined by the contact determination output Dt of the contact determining unit48that a two-handed contact is not taking place, and contact with the left hand is not occurring (NO in step S3), the process proceeds to step S4, and the operation permission determining unit52carries out an operation refusal process. At this time, the operation permission determining unit52outputs a gate signal Gs of an “L level” (permission not granted) to the gate circuit54.

When the gate signal Gs of the “L level” (permission not granted) is input from the operation permission determining unit52, the gate circuit54interrupts the input signal Din from the input device26of the vehicle-mounted device24. Consequently, the output device28does not respond, and the vehicle-mounted device24is maintained in an operation refusal state (operation prohibited state).

After the operation refusal process of step S4, in step S5, the operation permission determining unit52outputs a warning signal (notification signal) Swarn with respect to the output device56. Due to the warning signal (notification signal) Swarn, a possibility exists that the left hand16L of the driver H is free. Accordingly, the output device56outputs a display or a voice message from the speaker to indicate that the vehicle-mounted device24, for example, a navigation device, cannot be operated, and issues a warning (notification) to the vehicle occupant.

On the other hand, in step S3, when it is determined by the contact determination output Dt of the contact determining unit48that a two-handed contact or contact with the left hand is taking place (YES in step S3), the process proceeds to step S6. In step S6, the operation permission determining unit52outputs the gate signal Gs of an “H level” (permission granted) to the gate circuit54.

When it is determined that the driver H is in a two-handed contact state or a left-handed contact state with respect to the steering wheel14, the gate circuit54allows the input signal Din of the input device26to pass through, and outputs it to the output device28. Therefore, operations of the vehicle-mounted device24made by the fellow passenger are treated as valid.

Next, proceeding to step S7, it is determined whether or not the power switch has been placed in an OFF state. If the power switch is not in an OFF state (NO in step S7), the routine returns to step S2and process is continued. On the other hand, if the power switch is in an OFF state (YES in step S7), a determination is made to terminate the process.

In this case, according to the present embodiment, as shown inFIGS. 3 and 4, the first detection range40L for detecting the left hand (one hand)16L of the driver H is set to a region that is narrower than the second detection range40R for detecting the right hand (other hand)16R of the driver H. Therefore, the upper boundary42abetween the first contact sensor18L and the second contact sensor18R is arranged at a position that can be easily grasped by the left hand16L of the driver H. Accordingly, there are cases in which the left hand16L simultaneously grasps the first contact sensor18L and the second contact sensor18R while straddling across the upper boundary42a. On the other hand, the right hand16R of the driver H is separated from the upper boundary42a, and the upper boundary42ais not grasped thereby.

Accordingly, when only the contact signal from the first contact sensor18L is obtained, or when the contact signals are simultaneously obtained from the first contact sensor18L and the second contact sensor18R, it is determined that the left hand16L is grasping the steering wheel14. Consequently, input operations of the vehicle-mounted device24can be permitted.

On the other hand, in the case that there are no contact signals from the first contact sensor18L or the second contact sensor18R, or in the case that only a contact signal from the second contact sensor18R is obtained, it is possible to restrict the input operations of the vehicle-mounted device24. Consequently, with a simple and economical structure, it is possible to reliably restrict operations of the vehicle-mounted device24by the driver H while the vehicle is being driven.

More specifically, as shown inFIG. 4, on the upper half of the steering wheel14, the upper boundary42abetween the first detection range40L and the second detection range40R is disposed on a side proximate to the vehicle-mounted device24with respect to the vertical center line V of the steering wheel14. In addition, the space S1of the upper boundary42ais set to a dimension that is less than the width T of a first of the left hand16L of the driver H.

Therefore, with the left hand16L of the driver H, a posture is possible in which the first detection range40L is grasped (seeFIG. 3), and a posture is possible in which the first detection range40L and the second detection range40R are grasped simultaneously (seeFIG. 6). In both of these postures, since the driver H cannot operate the vehicle-mounted device24with the right hand16R, convenience can easily be enhanced by allowing the passenger in the passenger seat to operate the vehicle-mounted device24.

On the other hand, ordinarily, it is not possible for the first detection range40L and the second detection range40R to be simultaneously grasped by the right hand16R of the driver H while straddling across the upper boundary42a. Accordingly, when it is detected that both hands of the driver H are in a grasping state, it can be regarded that the left hand16L is not free. This makes it possible to suppress insofar as possible a situation in which the driver H is capable of operating the vehicle-mounted device24during traveling.

Furthermore, on the lower half of the steering wheel14, the lower boundary42bbetween the first detection range40L and the second detection range40R is disposed on the side proximate to the vehicle-mounted device24with respect to the vertical center line V of the steering wheel14. In addition, the space S2of the lower boundary42bis set to a dimension that is greater than the width T of a first of the left hand16L of the driver H.

Therefore, the driver H is incapable of grasping the first detection range40L and the second detection range40R simultaneously only by the right hand16R with the lower boundary42binterposed therebetween. Therefore, it is possible to reliably prevent an erroneous recognition that the steering wheel14is being grasped by the left hand16L, in spite of the fact that the left hand16L is free.

Further still, on the outer periphery of the steering wheel14, a plurality of divided leather members are adjacent to each other and wound over a predetermined region, thereby forming the leather layers38L,38R. At that time, a conductive paint preferably is applied to each of the leather layers38L,38R to thereby constitute a first touch sensor and a second touch sensor in the form of the first contact sensor18L and the second contact sensor18R. In addition, an insulating treatment is applied between the leather layers38L,38R themselves. In accordance with this feature, the space S1of the upper boundary42ais set to a dimension, and more specifically, a narrow dimension, which is less than the width T of a first of the left hand16L of the driver H.

Moreover, according to the present embodiment, although the steering wheel14is a right-hand steering wheel, the present invention is not limited to this feature, and the steering wheel14may be a left-hand steering wheel.

In such a case, the one hand of the driver H is the right hand16R, and the other hand of the driver H is the left hand16L, while in addition, the second contact sensor18R that detects contact by the right hand16R becomes the first contact sensor18R. On the other hand, the first contact sensor18L that detects contact by the left hand16L becomes the second contact sensor18L. The detection range detected by the first contact sensor18R is set to be narrower than the detection range detected by the second contact sensor18L, and as shown by the two-dot dashed lines inFIG. 4, an upper boundary42cis set to a position capable of being grasped by the right hand16R. Consequently, similar effects can be obtained in the case that the steering wheel14is a right-hand steering wheel, and in the case that the steering wheel14is a left-hand steering wheel.

Further, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications could be adopted therein without departing from the essence and gist of the present invention.