Abstract:
Disclosed is controlling a vibration of a vibration generating device configured to reciprocatively vibrate an operating body movably supported in a first direction and a second direction which are opposite to each other, a driving signal being transmitting to a first interval and a second interval in which vibration frequencies of acceleration during movement of the operating body are different from each other, the first interval being an initial motion interval when the operating body moves toward the first direction, the second interval being an initial motion interval when the operating body moves toward the second direction. The vibration frequency of the second interval is smaller than the vibration frequency of the first interval which is equal to or smaller than 250 Hz, and the vibration frequency of the second interval is greater than the vibration frequency of the first interval which is equal to or greater than 250 Hz.

Description:
CLAIM OF PRIORITY 
     This application claims benefit of Japanese Patent Application No. 2015-055227 filed on Mar. 18, 2015, which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic apparatus that gives a sense of touch of a vibration to a finger when a touch operation of an operating body is performed using the finger, and a vibration control method of controlling the vibration. 
     2. Description of the Related Art 
     Hitherto, electronic apparatuses with vibration feedback have been proposed which give a sense of touch of a vibration to a finger when the finger is touched to an operating body to thereby bring the operating body into operation. 
     Among them, an electronic apparatus has been proposed which gives a stimulus to a finger using vibration acceleration capable of being recognized by a Pacinian corpuscle included in the finger for bringing an operating body into operation, thereby allowing an operator to recognize a stimulus. 
     The Pacinian corpuscle is a receptor observed in the skin, is present sparsely 2 mm or more under the skin, and is able to sense instantaneous stimuli and vibrations. Meanwhile, the peak value of a vibration frequency capable of being sensed by the Pacinian corpuscle is said to be 250 Hz, and a vibration having a vibration frequency closer to 250 Hz has a greater tendency to be sensed. 
     WO2013/186841 discloses a technique in which information is input by touching a finger to a touch panel in an electronic apparatus such as a smartphone or a cellular phone. The touch panel has a structure in which a vibration is given using a vibration frequency capable of being recognized by the Pacinian corpuscle, and a stimulus is given to a finger for bringing the touch panel into operation. 
     In the technique disclosed in WO2013/186841, the vibration frequency for giving an acceleration stimulus to the Pacinian corpuscle is always fixed regardless of an elapse of time. According to such a technique, even when a predetermined time has elapsed after the vibration of the touch panel, the acceleration stimulus transmitted to an operator&#39;s finger remains in the vibration frequency having a great influence on the Pacinian corpuscle, and thus a vibration transmitted to the finger stays behind. Therefore, there is a problem in that the operator is not able to obtain a sharp and clear operation feeling. 
     SUMMARY OF THE INVENTION 
     The present invention provides an electronic apparatus and a vibration control method which are capable of obtaining a sharp and clear operation feeling (sense of touch) when an operator performs a touch operation on an operating body using a finger. 
     In order to solve the above-mentioned problems of the related art, according to the present invention, there is provided an electronic apparatus including: an operating body movably supported in a first direction and a second direction which are opposite to each other; vibration generating means for reciprocatively vibrating the operating body; and vibration control means for transmitting a driving signal to the vibration generating means, and controlling a vibration of the vibration generating means. The vibration control means transmits a driving signal to a first interval and a second interval in which vibration frequencies of acceleration during movement of the operating body are different from each other. The first interval is an initial motion interval when the operating body moves toward the first direction. The second interval is an initial motion interval when the operating body moves toward the second direction. The vibration frequency of the first interval and the vibration frequency of the second interval satisfy any of the following Expressions (1) and (2).
 
The vibration frequency of the second interval&lt;the vibration frequency of the first interval≦250 Hz  (1)
 
250 Hz≦the vibration frequency of the first interval&lt;the vibration frequency of the second interval  (2)
 
     According to such a configuration, a stimulus is given to a finger using vibration acceleration capable of being recognized by the Pacinian corpuscle included in the finger for bringing the operating body into operation, and a stimulus (vibration) does not remain therein, thereby allowing a sharp and clear sense of touch to be given to an operator. 
     Preferably, the vibration generating means includes a transmission member configured to transmit a force to the operating body and an actuator configured to drive the transmission member in the first direction, and is provided with an elastic member capable of being compressed when the transmission member is driven by the actuator in the first direction. 
     According to such a configuration, it is possible to smoothly perform the movement of the transmission member in the second direction. 
     Preferably, detection means for detecting movement of the transmission member in a second direction is further provided. 
     According to such a configuration, the position of a bottom dead center of the transmission member in the first direction is detected, and thus it is possible to send a signal to the vibration control means, and to sharply perform switching of a vibration. 
     According to the present invention, there is provided a vibration control method of controlling a vibration of vibration generating means for reciprocatively vibrating an operating body movably supported in a first direction and a second direction which are opposite to each other, the method including a step of transmitting a driving signal to a first interval and a second interval in which vibration frequencies of acceleration during movement of the operating body are different from each other, the first interval being an initial motion interval when the operating body moves toward the first direction, the second interval being an initial motion interval when the operating body moves toward the second direction, and the vibration frequency of the first interval and the vibration frequency of the second interval satisfying any of the following Expressions (1) and (2).
 
The vibration frequency of the second interval&lt;the vibration frequency of the first interval≦250 Hz  (1)
 
250 Hz≦the vibration frequency of the first interval&lt;the vibration frequency of the second interval  (2)
 
     According to such a method, a stimulus is given to a finger using vibration acceleration capable of being recognized by the Pacinian corpuscle included in the finger for bringing an operating body into operation, and a stimulus (vibration) does not remain therein, thereby allowing a sharp and clear sense of touch to be given to an operator. 
     According to the present invention, it is possible to provide an electronic apparatus and a vibration control method which are capable of obtaining a sharp and clear operation feeling (sense of touch) when an operator performs a touch operation on an operating body using a finger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram schematically illustrating an electronic apparatus showing an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view illustrating a state before the operation of a vibration generating device of the electronic apparatus shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view illustrating a state after the operation of the vibration generating device of the electronic apparatus shown in  FIG. 1 . 
         FIG. 4  is a graph illustrating a relationship between a vibration frequency and the hardness of an elastic member used in the electronic apparatus showing the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a block diagram schematically illustrating an electronic apparatus  100  showing an embodiment of the present invention,  FIG. 2  is a cross-sectional view illustrating a state before the operation of a vibration generating device  1  of the electronic apparatus  100 , and  FIG. 3  is a cross-sectional view illustrating a state after the operation of the vibration generating device  1 . 
     As shown in  FIG. 1 , the electronic apparatus  100  includes the vibration generating device  1  that gives a vibration to an operating body  10  and a vibration control device  50  that controls the vibration of this vibration generating device  1 . The vibration generating device  1  includes an actuator  20  that generates a vibration and a transmission member  25  that transmits the vibration to the operating body  10 . 
     The vibration control device  50  includes a solenoid drive circuit  51  that sends a driving control signal to the actuator  20  of the vibration generating device  1 , a coordinate detection device  56  that detects a touch of a finger  40  with the operating body  10 , an electrostatic IC  52  to which a detection signal is sent from the coordinate detection device  56 , a pressure-sensitive amplifier  54  that amplifies a signal of the pressure-sensitive sensor  53  which is detection means for detecting a movement of the operating body  10 , and a CPU  55  that receives a signal from the electrostatic IC  52  and the pressure-sensitive amplifier  54  and sends a driving signal to the solenoid drive circuit  51 . The driving of the vibration generating device  1  is controlled by a control signal of the CPU  55 , and a vibration is given to the operating body  10 . 
     The solenoid drive circuit  51  transmits a driving signal to a first interval and a second interval in which vibration frequencies of acceleration during the movement of the operating body  10  are different from each other. The first interval is an initial motion interval when the operating body  10  moves toward a first direction, and the second interval is an initial motion interval when the operating body  10  moves toward a second direction. The vibration frequency of the first interval and the vibration frequency of the second interval satisfy any of the following Expressions (1) and (2).
 
The vibration frequency of the second interval&lt;the vibration frequency of the first interval≦250 Hz  (1)
 
250 Hz≦the vibration frequency of the first interval&lt;the vibration frequency of the second interval  (2)
 
     The first direction of the operating body  10  means a direction in which a plunger  26  of the transmission member  25  of the vibration generating device  1  is excited, and the plunger  26  moves in a Z direction (upward direction) in  FIG. 1  toward the finger  40 . In addition, the second direction means the Z direction (downward direction) in  FIG. 1  in which the plunger  26  is pulled back, and the plunger  26  moves away from the finger  40 . 
     Expression (1) is a relational expression when the standard strength of a third elastic member  32  is used. As represented in Expression (1), an operator touches the operating body  10  and pushes down the operating body  10 , so that the vibration frequency of the first interval which is an initial motion interval in which the plunger  26  moves toward the first direction is set to, for example, 200 Hz which is equal to or lower than 250 Hz. The vibration frequency of the second interval which is an initial motion interval in which the plunger  26  moves toward the second direction is set to be lower than the frequency of the first interval, for example, 100 Hz. 
     The peak value of the vibration frequency of an acceleration stimulus capable of being sensed by a Pacinian corpuscle is said to be approximately 250 Hz. Therefore, in a case of the first interval in which the vibration frequency of 200 Hz which is a value close to 250 Hz is obtained, the operator can greatly feel a vibration on the finger. When the plunger  26  moves to the interval (second interval) in a direction away from the finger, the vibration frequency is set to 100 Hz lower than the vibration frequency of the first interval, and thus it is not more likely to feel a vibration on the finger than in the first interval. 
     In addition, Expression (2) is a relational expression when the high strength of the elastic member is used. As represented in Expression (2), the operator touches the operating body  10  and pushes down the operating body  10 , so that the vibration frequency of the first interval which is an initial motion interval in which the plunger  26  moves toward the first direction is set to be equal to or higher than 250 Hz. The vibration frequency of the second interval which is an initial motion interval in which the plunger  26  moves toward the second direction is set to be higher than the frequency of the first interval. 
     Therefore, when the frequency is a frequency close to 250 Hz, the operator can greatly feel a vibration on the finger. When the plunger  26  moves to the interval (second interval) in a direction away from the finger, the vibration frequency is set to be higher than the vibration frequency of the first interval, and thus it is not more likely that the operator feels a vibration on the finger than in the first interval. 
     As shown in  FIG. 2 , the vibration generating device is configured such that a bracket  4  is fixed onto a substrate  3 , and that a base  2  is constituted by the substrate  3  and the bracket  4 . 
     A plurality of guide shafts  5  are fixed to the upper portion of the bracket  4 , and the operating body  10  is guided to the guide shafts  5  and is supported so as to freely move back and forth in the Z direction (vertical direction). The operating body  10  is guided by the plurality of guide shafts  5 , and thus is vertically movable while maintaining a horizontal posture. A biasing spring  6  is provided between the bracket  4  and the operating body  10 , and the operating body  10  is biased by the biasing spring  6  upward along a Z-axis. 
     The operating body  10  is configured such that an operating base member  11  and an operation knob  12  installed thereon are fixed to each other. The operating base member  11  is made of a metal or synthetic resin, and is supported by the plurality of guide shafts  5  so as to be capable of reciprocating in the Z direction. The operation knob  12  is formed of a synthetic resin material, has the coordinate input device  56  such as an electrostatic sensor mounted on its surface  12   a  or its rear surface  12   b , and is configured to be capable of detecting which position on the operation knob  12  the operator&#39;s finger  40  touches. 
     The actuator  20  is fixed onto the lower surface of a ceiling board  4   a  of the bracket  4 . The actuator  20  is a uniaxial driving actuator, and is a solenoid mechanism. As the uniaxial actuator, a voice coil motor or a linear actuator may be used in addition to the solenoid mechanism. 
     A fixed portion of the actuator  20  which is a solenoid mechanism is constituted by an inside yoke  21  and an outside yoke  22  which are formed of a magnetic metal material, and an exciting coil  23  which is held inside of both the yokes  21  and  22 . A movable portion of the actuator  20  includes a transmission member  25 . The transmission member  25  is constituted by the plunger  26  that moves back and forth in a Z-axis direction through the inside yoke  21 , a movable yoke  27  which is suctioned into the inside yoke  21 , a biasing portion  28  fixed to the lower end of the movable yoke  27 , and a pressing portion  29  formed on the lower end. 
     The plunger  26  is a metal shaft. A thrust bearing  7  is fixed onto the upper surface of the bracket  4 , and the plunger  26  is slidably supported by the thrust bearing  7 . The thrust bearing  7  is constituted by an impregnation bearing which is made of a metal and contains lubricating oil. 
     A first elastic member  31  is fixed to the upper tip  26   a  of the plunger  26  constituting the transmission member  25 . The first elastic member  31  is formed of synthetic rubber, a foamed synthetic resin, or the like, and is elastically deformable in a compression direction.  FIG. 2  shows a state in which electrical conduction to the exciting coil  23  of the actuator  20  is not allowed. 
     The third elastic member  32  is interposed between the outside yoke  22  and the biasing portion  28  of the transmission member  25 . Similarly to the first elastic member  31 , the third elastic member  32  is formed of a material, such as synthetic rubber or a foamed synthetic resin, which is elastically deformable in a compression direction. As shown in  FIG. 2 , when electrical conduction to the exciting coil  23  is not allowed, the transmission member  25  is biased downward so as not to move in a descending state by pressurization which is exerted by the third elastic member  32 . Meanwhile, the third elastic member  32  is fixed to the biasing portion  28 , and may have a structure in which the upper portion thereof comes into contact with the lower surface of the outside yoke  22  without being fixed thereto. 
     A second elastic member  35  is provided on the substrate  3  of the base  2 . Similarly to the first elastic member  31 , the second elastic member  35  is formed of a material, such as synthetic rubber or a foamed synthetic resin, which is elastically deformable in a compression direction. 
     In this embodiment, the portion of the second elastic member  35  is provided with the pressure-sensitive sensor  53  (detection means). When the transmission member  25  moves further downward from the posture shown in  FIG. 2 , the second elastic member  35  is pressed by the pressing portion  29  of the transmission member  25 . In this case, the pressure-sensitive sensor  53  detects the amount of operation pressure of the plunger  26  of the transmission member  25 , and sends the signal to the pressure-sensitive amplifier  54 . 
     Meanwhile, in the present invention, when the second elastic member  35  and the pressure-sensitive sensor  53  are formed separately from each other, and the transmission member  25  is pressed downward, an upward elastic force may be exerted by the second elastic member  35  and the pressure-sensitive sensor  53  operate. 
     As shown in  FIG. 3 , when electrical conduction to the exciting coil  23  of the actuator  20  is allowed, the inside yoke  21  is magnetized due to its current magnetic field, the movable yoke  27  is suctioned into the inside yoke  21 , and the transmission member  25  ascends along the Z-axis which is the first direction. In this case, a first gap M is formed between the pressing portion  29  of the transmission member  25  and the second elastic member  35 . 
     Here, reference is now made to  FIG. 4  to describe a change in the characteristics of vibration frequency in accordance with the hardness of the third elastic member  32 . The solid line A of  FIG. 4  shows that the spring attitude of the third elastic member  32  is standard, the broken line B shows that the hardness of the second elastic member  32  is a hardness of ½ times the spring hardness of the solid line, and the dashed-dotted line C shows that the hardness of the second elastic member  32  is a hardness of 8 times the practical spring hardness. In  FIG. 4 , the standard spring hardness shows that the pushing-up speed of the operating body  10  caused by the ascent of the plunger  26  and the descending speed of the plunger  26  are balanced. The low hardness can cause the operating body  10  to be easily pushed up together with the ascent of the plunger  26 , which leads to fast arrival at the peak value of vibration acceleration. However, since a repulsive force becomes weaker to that extent, the descent of the plunger  26  becomes slower. The high hardness causes time to be taken to push up the operating body  10 , which leads to late arrival at the peak value of vibration acceleration. However, the repulsive force becomes higher, and the descent of the plunger  26  becomes faster. 
     Next, an operation and a vibration control method of the vibration generating device  1  will be described. As shown in  FIG. 2 , when electrical conduction to the exciting coil  23  of the actuator  20  is not allowed, the transmission member  25  descends, and downward pressurization is given to the transmission member  25  from the third elastic member  32 . 
     When the finger  40  is touched to the surface  12   a  of the operation knob  12 , the touch of the finger  40  is detected by the coordinate detection device  56  such as an electrostatic sensor which is mounted on the operation knob  12 . The detection signal is sent to the electrostatic IC  52 . When the finger  40  is brought into operation along the surface  12   a , the movement state of the touch position of the finger  40  is detected by the coordinate detection device  56 . When the finger  40  is caused to move on the surface  12   a  of the operation knob  12 , a cursor display moves on a display screen which is not shown. After the cursor display is caused to move to the position of any menu display, it is possible to perform a selection determination operation of a menu by pressing the operation knob  12  using a downward force F 1  in  FIG. 2 . 
     As shown in  FIG. 2 , when the downward pressing force F 1  is given to the operating body  10  in the pressing operation of the finger  40 , the operating base member  11  is guided to the guide shafts  5  and descends. Then, the operating body  10  is caused to move downward through the first elastic member  31  together with the transmission member  25 . The second elastic member  35  is pressed in the pressing portion  29  of the transmission member  25 , the pressure-sensitive sensor  53  detects the touch, and a switching signal is generated. The switching signal is sent to the CPU  55  through the pressure-sensitive amplifier  54 . Then, the solenoid drive circuit  51  starts up, and a driving current is given to the exciting coil  23  of the actuator  20 . This driving current has a pulse shape for a short time and is given only one shot. 
     When electrical conduction to the exciting coil  23  is allowed, as shown in  FIG. 3 , the movable yoke  27  is suctioned into the inside yoke  21 , the transmission member  25  is lifted up, the operating base member  11  of the operating body  10  is pushed upward by the first elastic member  31  fixed to the upper tip  26   a  of the plunger  26 , and bending is given to the operating body  10  in a state where the first elastic member  31  is contracted and the third elastic member  32  is contracted. 
     Such a state is the first interval which is an initial motion interval in which the plunger  26  moves toward the first direction (Z direction in  FIG. 3 , upward direction). In this interval, the vibration frequency which is applied to the operating body  10  is set to 200 Hz, and is set to a value close to 250 Hz which is the peak of the vibration frequency of acceleration capable of being sensed by the Pacinian corpuscle. Therefore, the operator can feel a sense of touch (vibration) on the finger  40 . 
     Immediately after that, when electrical conduction to the exciting coil  23  is cut off, and the suction force of a solenoid mechanism is released, the transmission member  25  moves downward due to the elastic restoring force of the first elastic member  31  contracted, the bending elastic force of the operating body  10 , and the elastic restoring force of the third elastic member  32 , and the second elastic member  35  is contracted in the pressing portion  29  on the lower end of the transmission member  25 . 
     Such a state is the second interval which is an initial motion interval in which the plunger  26  moves toward the second direction (Z direction in  FIG. 3 , downward direction). In this interval, the vibration frequency which is applied to the operating body  10  is set to 100 Hz lower than the vibration frequency of the first interval. This vibration frequency is set to a value far away from 250 Hz which is the peak value of the vibration frequency obtained by the Pacinian corpuscle, and thus the operator is not able to feel a vibration on the finger  40 . 
     Therefore, when the operator touches and operates the operating body  10 , the operator feels only an initial vibration frequency given to the operating body  10  in the Pacinian corpuscle, and thus it is possible to obtain a sharp and clear operation feeling (sense of touch) on the finger  40 . 
     Meanwhile, when the vibration frequency of the first interval is set to be higher than 250 Hz and the vibration frequency of the second interval is set to be higher than the vibration frequency of the first interval even in a case where the hardness of the third elastic member  32  is high, it is possible to greatly feel a vibration during the movement of the operating body  10  in the first direction, and thus it is not likely to feel a vibration during the movement of the operating body  10  in the second direction. Therefore, it is possible to obtain a sharp and clear operation feeling (sense of touch) on the finger  40 . 
     The present invention is not limited to the aforementioned embodiment. That is, those skilled in the art may variously change, combine, sub-combine, and substitute the components of the aforementioned embodiment within the technical scope of the present invention or its equivalents. 
     The present invention can be applied to various electronic apparatuses without being limited to a consumer electronic apparatus and an in-vehicle electronic apparatus, insofar as a finger touches an operating body and the operating body is brought into operation. 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims of the equivalents thereof.