Patent Publication Number: US-2015060257-A1

Title: Switch system

Description:
FIELD OF THE INVENTION 
     The present invention relates to a switch system having touch switches. 
     BACKGROUND OF THE INVENTION 
     There are known switch systems in which an operator touches an operation surface with a finger, and a charge in electrostatic capacitance caused by the touch is sensed. For example, a switch system is attached to a spoke of a steering wheel in order to operate an onboard instrument. The technology disclosed in JP-A 2009-298285 is an example of this type of conventional technology. 
     In a vehicle steering switch such as the one in JP-A 2009-298985, an operation unit comprising a touch switch capable of gesture operations such as a swipe operation is attached to a spoke. 
     An operator can operate any desired onboard instrument by touching the operation surface of the touch switch with a finger. A car navigation system is a possible example of an onboard instrument. 
     However, when the switch is disposed in a narrow area such as a spoke, there is a risk of accidentally operating a different switch than the switch necessary for the operation. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a switch system that can be operated accurately even when disposed in a narrow area. 
     According to the present invention, there is provided a switch system wherein an operator touches an operation surface of a switch with a finger, a change in electrostatic capacitance caused by the touch is sensed, and movement of the finger of the operator is detected, and wherein the operation surface of the switch is formed into concavities or convexities. 
     In the present invention as explained above, the operation surface of the switch is formed into concavities or convexities. Due to the operation surface being formed into concavities or convexities, the operator can easily recognize that he is touching the operation surface of the switch. The operator can thereby be prevented from touching the finger to an incorrect area, and the operator can accurately perform any desired operation. 
     Preferably, the areas formed into concavities or convexities are formed over the entire range in which the operator can perform operations. 
     Specifically, the operator performs a switch sliding operation in the range of the areas formed into concavities or convexities. The accuracy of operation can be further secured by clarifying the range in which the operation can be performed. 
     Preferably, a general surface at the peripheral edge of the operation surface of the switch is a smooth surface. 
     The operation surface is formed into concavities or convexities, while the general surface unrelated to operations is formed into a smooth surface. The design of the switch can be improved due to the three-dimensional operation surface and the two-dimensional general surface being continuous. 
     Preferably, the operation surface of the switch is disposed on a spoke of a vehicle steering wheel; and the areas of the concavities or convexities are formed along an arc of a preset designated radius centered around an area in the vehicle steering wheel that is touched by the base of the thumb of operator when gripping a rim. 
     Specifically, the areas of the concavities or convexities and the switch are disposed so as to be aligned along the trajectory of the thumb of the operator gripping the rim. The operator can thereby operate the switch with natural finger movements. Specifically, the operability of the switch can be improved by employing this configuration. 
     Preferably, the operation surface of the switch is disposed on a substantially T-shaped spoke of the vehicle steering wheel, which comprises a rim and the spoke, the spoke being formed integrally on the inner periphery of the rim; the vehicle steering wheel is configured so that the operator grips the proximity of a point of intersection between the rim and a laterally extending side of the substantially T-shaped spoke; and a line through the areas formed into the concavities or convexities intersects a line at an incline so as progress outward from the bottom to the top, the line extending perpendicular to the laterally extending side. 
     Specifically, the areas of the concavities or convexities and the switch are disposed so as to be aligned along the trajectory of the thumb of the operator gripping the rim. The operator can thereby operate the switch with natural finger movements. Specifically, the operability of the switch can be improved by employing this configuration. 
     Preferably, the switch is a first switch; the spoke also has a second switch; the second switch is disposed in an area closer to the rim than the first switch; and the switch system has a control unit for assessing that only a contact signal of the first switch has been detected when contact signals are simultaneously received from both the first switch and the second switch. 
     The second switch is disposed in a position closer to the rim than the first switch. When the first switch is operated while the rim is gripped, there is a risk that the second switch will be mistakenly touched simultaneously. When both the first and second switches are touched simultaneously, the instrument can be controlled as intended by the operator by performing control so that the operation of the second switch is invalidated. The operability of the switches is thereby further improved. 
     Preferably, the operation surface of the first switch is tilted to the front in the vehicle body relative to the operation surface of the second switch so as to move away from the finger of the operator. 
     The operation surface of the first switch and the operation surface of the second switch are disposed along different directions. Faulty operations can thereby be suppressed, and the accuracy of operation can be further improved. 
     Preferably, a backlight for illuminating the operation surface of the switch is provided in the proximity of the switch; and the backlight is turned on by the detection of contact on the switch by the operator. 
     The area where the switch is disposed is made visually clear. The accuracy of operating the operation unit can thereby be further improved. 
     Preferably, the switch system is attached to a steering wheel; the steering wheel comprises a rim for steering the vehicle and a spoke formed integrally on the inner peripheral surface of the rim; the operation surface is positioned in an area within the spoke allowing operation while the rim is gripped; and the operation surface is positioned farther forward in the vehicle body than a plane fanning out from an area where the distal end of the thumb of the operator in a normal driving posture touches the rim; the axis being a direction orthogonal to the plane of the steering wheel; and the center being the area touched by the ball of the thumb of the operator when the operator grips the rim. 
     There is a high height to the operation surface from a line drawn parallel to the operation surface from the apex of the rim, in alignment with the orientation of the thumb while the steering handle is being gripped normally. The operation unit can thereby be swiped by the thumb while the rim is gripped. When this operation is performed, the operation is with the thumb upright in accordance with the forward-retreating formation. The contact surface area of the thumb on the operation unit can be reduced because the distal end of the thumb is in contact with the operation surface. Due to the smaller contact surface area, mistaken contact on switches in the proximity of the area being operated can be suppressed. The accuracy of operating the operation unit can thereby be improved. Additionally, because the thumb operates the unit while upright, the operation is performed more easily. Operation with the thumb is also made easier because the base of the thumb (ball of the thin b) is in contact with the rim. 
     Preferably, the operation surface is inclined forward in the vehicle body from the outer peripheral edge of the rim toward the center. 
     The operation with a more natural posture is thereby made possible. 
     Preferably, the operation surface is positioned in a location where the operation surface can be operated by the thumb of the operator while the bail of the thumb is in contact with the rim. 
     Therefore, operation with a more natural posture is made possible because the operation surface is disposed within the length of the thumb. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Several preferred embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic view of a vehicle equipped with the switch system according to the first embodiment of the present invention; 
         FIG. 2  is a cross-sectional view along line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view along line  3 - 3  of  FIG. 1 ; 
         FIGS. 4A and 4B  are enlarged views of the operation unit shown in  FIG. 1 ; 
         FIG. 5  is a flowchart for describing the relationship between the first switch and the second switch shown in  FIG. 1 ; 
         FIG. 6  illustrates the effect of the vehicle steering switch shown in  FIG. 1 ; 
         FIG. 7  is a cross-sectional view of an operation unit equipped with the switch system of the second embodiment of the present invention; 
         FIG. 8  is a front view of an operation surface of the switch system of the third embodiment of the present invention; and 
         FIGS. 9A and 9B  illustrate an operation surface of the switch system of the fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention are described below with reference to the accompanying drawings. In the drawings, the terms “left” and “right” refer to the left and right referencing an occupant of the vehicle, and the terms “front” and “back” refer to the front and back referencing the traveling direction of the vehicle. Fr in the drawings indicates the front, Rr indicates the back, Ce indicates the vehicle-width middle, Up indicates up, and Dn indicates down. 
     First Embodiment 
     As shown in  FIG. 1 , a vehicle steering wheel  20  (referred to below simply as the “steering wheel  20 ”) for steering a vehicle  10  is provided in the front inside the passenger compartment. 
     A monitor  12   a  of an audio device  12  (an onboard instrument  12 ) is provided in the proximity of the steering wheel  20 , and two blower vents  13   a,    13   a  of an air-conditioning device  13  (an onboard instrument  13 ) are provided on either side of the monitor  12   a.    
     The monitor  12   a  serves as a monitor for a car navigation system. 
     The audio device  12  and the air-conditioning device  13  have a control unit  15 , and the level of noise and the rate of air blown are controlled by the control unit  15 . Only one control unit  15  is conceptually shown. Specifically, two or more control units  15  can be disposed in any desired locations. 
     The steering wheel  20  is composed of a rim  21  that is substantially circular and can be steered by a vehicle occupant, a substantially T-shaped spoke  22  formed integrally on the inner peripheral surface of the rim  21 , a horn switch cover  23  attached to the middle of the spoke  22  and placed over a horn switch, a first operation unit  30  (an operation unit  30 ) provided adjacent to the left side of the horn switch cover  23  and used for operating the audio device  12 , and a second operation unit  40  (an operation unit  40 ) provided adjacent to the right side of the horn switch cover  23  and used for operating the air-conditioning device  13 . 
     The first operation unit  30 , the horn switch cover  23 , and the second operation unit  40  are disposed along a straight line. The first operation unit  30 , the horn switch cover  23 , and the second operation unit  40  correspond to a laterally extending side  25  of the substantially T-shaped spoke  22 . 
     The horn switch cover  23  is disposed in the center C of the rim  21 . 
     The first operation unit  30  and the second operation unit  40  are both hooked up to the control unit  15 . 
     The point of intersection between the laterally extending side  25  of the spoke  22  and a longitudinally extending side  26  coincides with the center C of the rim  21 . 
     The first operation unit  30  is an area for performing operations of the audio device  12 . When an operator operates the first operation unit  30 , an operation signal is generated. Based on the operation signal, the control unit  15  changes a song selection or the sound level. 
     The second operation unit  40  is an area for performing operations of the air-conditioning device  13 . When an operator operates the second operation unit  40 , an operation signal is generated. Based on the operation signal, the control unit  15  switches between heating and cooling or changes the temperature. 
     The first operation unit  30  and the second operation unit  40  have the same essential configuration, and the first operation unit  30  primarily is described below as an example. 
     As shown in  FIG. 2 , a pipe-shaped material is used as the rim  21 . The spoke  22  extends from the inner periphery of the rim  21  toward the center C of the rim  21  (see  FIG. 1 ) at a slight, forward incline. The spoke  22  is directly connected to the inner periphery of the rim  21 . 
     An opening  22   a  is formed in the spoke  22 . The first operation unit  30 , consolidated into a unit, is embedded in the opening  22   a.    
     The opening  22   a  is formed toward the driver seat. An operation surface  30   a  of the first operation unit  30  is disposed facing the driver seat. The operation surface  30   a,  together with the spoke  22 , is inclined slightly forward toward the center of the rim  21 . 
     An extending part  22   b  that extends forward is formed in the end part of the spoke  22 . Due to the formation of the extending part  22   b,  a proximal end part  22   c  of the spoke  22  and the peripheral edge area of the opening  22   a  are formed in the shape of a step. The end part of the spoke  22  can also be referred to as the border between the rim  21  and the spoke  22 . Specifically, the border between the rim  21  and the spoke  22  is formed into the shape of a step so that with the rim  21  as a reference, the spoke  22  (at least the area where the first operation unit  30  is attached) separates forward. 
     Other options of a configuration in which the border between the rim  21  and the spoke  22  is formed into a step shape include bending the spoke  22 , as well as changing the shape of part of the rim  21 , and placing a separate member for forming a step in between the rim  21  and the spoke  22 . 
     Returning to  FIG. 1 , a first switch  31  (a switch  31 ) is disposed in an area within the first operation unit  30  that is in the proximity of the horn switch cover  23 . Specifically, the first switch  31  (the switch  31 ) is disposed in the side near the center of the rim  21 . A second switch  32  is disposed adjacent to the first switch  31 , on the side near the rim  21 . A third switch  33  is disposed below the second switch  32 . 
     The first to third switches  31  to  33  are electrostatic capacitance switches that detect touching by an operator, for example. 
     Touch switches other than those of the electrostatic capacitance type can also be employed as the first to third switches  31  to  33 . 
     The first to third switches  31  to  33  are disposed within an area enclosed by a frame  34 . A distal end of the frame  34  protrudes nearer to the operator than the operation surface  30   a  of the first operation unit  30 . 
     First to third switches  41  to  43  are disposed in the second operation unit  40  as well, similar to the first operation unit  30 . 
     For example, a first switch  41  (a switch  41 ) is operated when a temperature setting is adjusted, a second switch  42  is operated when an air-blowing mode is selected, and a third switch  43  is operated when cooling or heating is selected. 
     The switch system in the present invention is composed of either the first operation unit  30  and the control unit  15 , or the second operation unit  40  and the control unit  15 . 
     Referring to  FIG. 3 , an LED backlight  35  is installed in the first operation unit  30 . The backlight  35  is covered by a plastic operation panel  36 . An operation surface  31   a  of the first switch  31  is formed in part of the operation panel  36 . 
     A plurality of convexities  31   b  is formed in the operation surface  31   a  of the first switch  31 . The convexities  31   b  can be formed integrally in the operation panel  36  by extrusion molding. The convexities  31   b  are formed over the entire operation surface  31   a  of the first switch  31 . Specifically, the entire operation surface  31   a  of the first switch  31  is formed into convex shapes. 
     Blinder members  37  are affixed to the back surface of the operation surface  31   a  of the first switch  31 , in areas corresponding to the spaces between the convexities  31   b.  The convexities  31   b  alone thereby appear to be lit up when the backlight  35  is turned on. Specifically, due to the blinder members  37  being affixed in areas corresponding to the spaces between the convexities  31   b,  the convexities  31   b  are emphasized and the outward appearance of the first operation unit  30  can be improved. 
     The backlight  35  is turned on by detection of contact of the firs switch  31  by the operator. After being turned on, the backlight  35  is turned off by the elapse of a designated period. These controls are performed by the control unit  15  (see  FIG. 1 ). The area where the first switch  31  is disposed is made visually clear by the backlight  35  turning on. The accuracy of operating the first operation unit  30  can thereby be improved. 
     Referring to  FIG. 4A , the general surface  30   a  at the peripheral edge of the operation surface  31   a  is a smooth surface. The first operation unit  30  is operated by the thumb Th of the left hand gripping the rim  21 . 
     While gripping the rim  21 , the operator performs an operation (a swipe operation) of rotating the thumb Th about the base P 1  of the thumb. The area shown by the imaginary lines is the area in which the thumb Th can move while extended straight. Specifically, the area shown by the imaginary lines is the area in which the swipe operation can be performed. This area of possible movement supposes that the thumb is that of the average adult male (American). The operation surface  30   a  is formed underneath this area. 
     Referring to  FIG. 4B  as well, the first switch  31  is a switch for adjusting the sound level, and is disposed along a substantially vertical direction. When adjusting the sound level, the operator slides the thumb Th up and down on the operation surface  31   a  of the first switch  31 . The thumb Th is slid upward to raise the sound level, and the thumb Th is slid downward to lower the sound level. 
     More specifically, the thumb Th of the operator gripping the rim  21  is slid so as to move in a substantially arcuate trajectory L 1  about the base area P 1  of the thumb Th. The first switch  31  is disposed substantially in alignment with the trajectory L 1 . Specifically, the first switch  31  is disposed in a position overlapping the trajectory L 1  of the thumb Th of the operator. 
     The vehicular steering wheel  20  is configured so that the operator grips the proximities of the points of intersection between the rim and the laterally extending side  25  of the substantially T-shaped spoke. A line L 4  through the convexities  31   b  intersects a line L 3  extending perpendicular to the laterally extending side  25  (L 2 ), and does so at an incline so as progress outward from the bottom to the top. 
     The convexities  31   b  are formed along a preset arc L 1  of a designated radius, centered about the area P 1  in the steering wheel  20  that is adjoined by the base of the thumb Th of the operator gripping the rim  21 . The operator can thereby operate the first switch  31  by natural finger movements. Specifically, the operability of the first switch  31  can be improved by employing this configuration. 
     The convexities  31   b  are formed in the operation surface  31   a  of the first switch  31 . Due to the formation of the convexities  31   b,  the operator can easily recognize that he is touching the operation surface  31   a  of the first switch  31 . The operator can thereby be prevented from touching the thumb Th to an incorrect area, and the operator can accurately perform any desired operation. 
     The convexities  31   b  are formed over the entire area in which the swipe operation can be performed. Specifically, the operator performs the swipe operation of the first switch  31  within the range of the area where the convexities  31   b  are formed. The accuracy of operation can be further secured by clarifying the range in which the operation can be performed. 
     Furthermore, the general surface  30   a  at the peripheral edge of the operation surface  31   a  of the first switch  31  is a smooth surface. The convexities  31   b  are formed in the operation surface  31   a,  while the general surface  30   a  unrelated to operations is formed into a smooth surface. The design of the first switch  31  (the first operation unit  30 ) can be improved due to the three-dimensional operation surface  31   a  and the two-dimensional general surface  30   a  being continuous. 
     The second switch  32  is formed in the shape of a double circle, wherein an enter key  32   a  is disposed in the middle and a directional key  32   b  is disposed so as to enclose the enter key  32   a.  Furthermore, the second switch  32  is formed into a bowl shape so that the center of the double circle is the deepest. Faulty operation of the switches  31  to  33  can be further minimized by forming concavities and convexities in the second switch  32 . Specifically, the accuracy of operating the first operation unit  30  can be improved. 
     The second switch  32  is used to select a song title, for example. To select any desired song, the operator uses the directional key  32   b  to select a song title shown on the monitor  12   a  (see  FIG. 1 ), and uses the enter key  32   a  to choose the song. The operator then uses the thumb Th to press the enter key  32   a  or the directional key  32   b.    
     The third switch  33 , which is disposed along the direction in which the spoke  22  extends, is a switch for making music or radio selections, for example. Pressing the desired key switches between music, AM radio, and FM radio. The third switch  33  can also be operated by the thumb Th of the operator. 
     Referring to  FIGS. 1 and 5 , in step S 01 , the control unit  15  assesses whether or not the operator is touching the first switch  31 . More specifically, the control unit  15  assesses that the operator is touching the first switch  31  by receiving a detection signal from the first switch  31 . 
     When the operator is touching the first switch  31 , the sequence advances to step S 02 . In step S 02 , the control unit  15  invalidates the second switch  32 . Specifically, control of the audio device  12  based on an operation signal of the second switch  32  is not performed while the operator is touching the first switch  31 , even if the operator touches the second switch  32 . Specifically, when the control unit  15  simultaneously receives a contact signal from both the first switch  31  and the second switch  32 , the control unit  15  detects only the contact signals of the first switch  31 . 
     Referring again to  FIG. 4A , the second switch  32  is disposed in a position closer to the rim  21  than the first switch  31 . There is a risk that when the operator intends to operate the first switch  31  while gripping the rim  21 , the operator will accidentally touch the second switch  32  at the same time. When the operator simultaneously touches both the first and second switches  31 ,  32 , a control is performed so that the operation of the second switch  32  is invalid, whereby the audio device  12  can be controlled as intended by the operator. The operability of the switches is thereby further improved. 
     Returning to  FIGS. 5 and 1 , in step S 03 , the control unit  15  validates the first switch  31 . Specifically, an electric signal is sent from the control unit  15  to the first switch  31  on the basis of the operation performed by the operator. Based on this electric signal, the control unit  15  controls the audio device  12 . The order of step S 02  and step S 03  may be reversed. 
     When contact on the first switch  31  is not detected in step S 01 , the sequence advances to step S 04 . In step S 04 , the control unit  15  assesses whether or not the operator is touching the second switch  32 . More specifically, the control unit  15  assesses whether or not the operator is touching the second switch  32  by receiving a detection signal from the second switch  32 . 
     The sequence advances to step S 05  when the operator is touching the second switch  32 . In step S 05 , the control unit  15  validates the second switch  32 . Specifically, an electric signal is sent to the control unit  15  from the second switch  32  on the basis of the operation performed by the operator. Based on this electric signal, the control unit  15  controls the audio device  12 . 
     The sequence ends when contact on the second switch  32  is not detected in step S 04 . 
     Referring to the conventional example shown in  FIG. 6A , when a spoke  122  extends in a straight line from a rim  121 , the base P 1  of the thumb Th (the ball of the thumb) is separated from the rim  121 . Because the center of the trajectory of the thumb Th is separated from the rim  121 , it is difficult for the thumb Th to perform the swipe operation. The operational sensation is also poor when the thumb Th is laid down. 
     Furthermore, the thumb Th extends straight. Therefore, the trunk part of the thumb Th contacts an operation surface  130   a  of an operation unit  130 . The surface area of the part of the thumb Th making contact becomes larger, and there is a risk of mistaken contact on a switch in the proximity of the area being operated. Specifically, there is a low height H 1  to the operation surface  130   a  from a line L 1  drawn parallel to the operation surface  130   a  from the apex of the rim  121 . The surface area of the thumb Th in contact with the operation surface  130   a  thereby becomes larger. Due to the larger contact surface area, it is difficult to detect the operation and faulty operations are likely. 
     Referring to the embodiment shown in  FIG. 6B , the border between the rim  21  and the spoke  22  in the present invention is formed in the shape of a step so that the spoke  22  separates forward with the rim  21  as a reference. Therefore, there is a high height H 1  to the operation surface  30   a  from a line L 1  drawn parallel to the operation surface  30   a  from the apex of the rim  21 . When the first operation unit  30  is operated by the thumb Th while the rim  21  is gripped, the operation is with the thumb Th upright in accordance with the step shape formed by the border. The contact surface area of the thumb Th on the first operation unit  30  can be reduced because the distal end of the thumb Th is in contact with the operation surface  30   a.  Due to the smaller contact surface area, mistaken contact on switches in the proximity of the area being operated can be suppressed. The accuracy of operating the first operation unit  30  can thereby be improved. 
     Additionally, because the thumb Th operates the unit while upright, the operation is performed more easily. Operation with the thumb Th is also made easier because the base P 1  of the thumb Th is in contact with the rim  21 . 
     Furthermore, the peripheral edge of the operation surface  30   a  is enclosed by the frame  34 , and the distal end of the frame  34  protrudes nearer to the operator than the operation surface  30   a.  Therefore, the thumb Th operates the unit while upright in accordance with the need to avoid the distal end of the frame  34  when the first operation unit  30  is operated by the thumb Th while the rim  21  is gripped. The accuracy of operating the first operation unit  30  can thereby be further improved. 
     Furthermore, the operation surface  30   a  inclines forward in the vehicle body toward the center of the rim  21  from the outer peripheral surface. The operation surface can thereby be operated will a more natural posture. 
     Furthermore, the operation surface  30   a  is positioned in a location where it can be operated by the thumb Th of the vehicle occupant while the ball of the thumb is in contact with the rim  21 . The operation surface  30   a  can be operated with a more natural posture because it is disposed within the length of the thumb Th. 
     Second Embodiment 
     Next, a second embodiment of the present invention is described with reference to the drawings.  FIG. 7  shows a cross-sectional configuration of an operation unit equipped with the switch system of the second embodiment.  FIG. 7  corresponds to  FIG. 3  described above. Elements common to the first embodiment are denoted by the same symbols, and detailed descriptions thereof are omitted. 
     As shown in  FIG. 7 , a plurality of concavities  51   b  are formed in an operation surface  51   a.  Specifically, an operation surface  51   a  of a first switch  51  is formed into a concave shape. The concavities  51   b  are formed over the entire operation surface  51   a  of the first switch  51 . 
     Blinder members  37  are affixed to the back surface of the operation surface  51   a  of the first switch  51 , in areas corresponding to the concavities  51   b.  The areas between the concavities  51   b  thereby appear to be lit up when a backlight  35  is turned on. Specifically, due to the blinder members  37  being affixed in areas corresponding to the concavities  51   b,  the areas between the concavities  51   b  are emphasized and the outward appearance of the first operation unit  50  can be improved. The other designated effects of the present invention can still be achieved when such a configuration is used. 
     Third Embodiment 
     Next, a third embodiment of the present invention is described with reference to the drawings.  FIG. 8  shows an operation surface of a switch system of the third embodiment. Elements common to the first embodiment or the second embodiment are denoted by the same symbols, and detailed descriptions thereof are omitted. 
     Referring to  FIG. 8 , a plurality of convexities  31   b  are formed in a first operation unit  60 . These convexities  31   b  are formed along a line L 6  that is orthogonal to a line L 5  from the center C of the rim (see  FIG. 1 ) to the rim  21  (see  FIG. 1 ). These convexities  31   b  are formed at a slant relative to the line L 6 . The designated effects of the present invention can still be obtained in such a case. 
     Fourth Embodiment 
     Next, a fourth embodiment of the present invention is described with reference to the drawings.  FIGS. 9A and 9B  show an operation surface of a switch system of the fourth embodiment. Elements common to the first embodiment, the second embodiment, or the third embodiment are denoted by the same symbols, and detailed descriptions thereof are omitted. 
     Referring to  FIGS. 9A and 9B ,  FIG. 9B  is a view from the arrow  9 B in  FIG. 9A . An operation surface  71   a  of a first switch  71  of a first operation unit  70  is inclined forward in the vehicle body relative to an operation surface  72   c  of a second switch  72  so as to move away from the finger of the operator. The designated effects of the present invention can still be obtained in such a case. 
     Furthermore, the operation surface  71   a  of the first switch  71  and the operation surface  72   c  of the second switch  72  are disposed along different directions. It is thereby possible to suppress faulty operations and to further improve the accuracy of operation. 
     A case of operating an audio device was used as an example to describe the switch system of the present invention, but the switch system can also be used to operate other onboard instruments such as car navigation systems. Specifically, the onboard instrument is not limited to these examples as long as the object of the present invention can be achieved. Different embodiments can also be combined as appropriate as long as the actions and effects of the present invention are achieved. 
     An average adult male was assumed as the vehicle occupant in the present invention. The size of the hand and the position of the ball of the thumb were also assumed to be those of the average adult male. 
     The steering wheel in the present invention was presented in an embodiment in which the border between the rim  21  and the spoke  22  was formed in the shape of a step such that the spoke  22  separated forward with the rim  21  as a reference, but the border need not be formed in the shape of a step and may be formed in the shape of an inclined surface. 
     Obviously, various minor changes and modifications of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.