JP4002813B2 - Vibration generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibration generator for small portable electronic devices, which is useful for notification of incoming calls of a mobile phone.
[0002]
[Prior art]
In mobile phones, in order to notify the user of incoming calls even in places where ringing sounds cause trouble to the surroundings, the mobile phone itself or a dedicated device connected wirelessly to the mobile phone vibrates mainly. A method of applying mechanical stimulation to the user's body is employed. As such a vibration generator for a mobile phone, a small motor having an eccentric weight attached to a shaft is generally used, and a casing is obtained by rotating the motor at a relatively low speed of about several tens of Hz. Generate vibrations.
[0003]
However, in such a vibration generator, there is a problem that a large load is applied to the shaft and the bearing in order to rotationally drive the eccentric weight, and a failure is likely to occur. Therefore, the current vibration generator assumes only a life of about 3 years. In addition, the electric-mechanical conversion by the motor is not very energy efficient, and part of the energy is wasted as heat and the like, so that the power consumption tends to increase. As is well known, in portable electronic devices such as mobile phones, reduction in power consumption is an important issue as well as reduction in size and weight, and the amount of power consumed by the vibration generator cannot be neglected.
[0004]
In response to the above problems, vibration generators using piezoelectric vibrators have been proposed. For example, an example of a vibration generator disclosed in Patent Document 1 is shown in FIG. In this vibration generator, one end of a vibration transmitting member 34 is fixed to the center of the lower surface of the piezoelectric diaphragm 31 formed by sandwiching the diaphragm 33 from both sides with the piezoelectric element 32, and the other end is attached to, for example, a casing 35 of a mobile phone. It is fixed. One end of an elastic member 36 is connected to the outer peripheral edge of the piezoelectric diaphragm 31, and a weight 37, which is a mass load, is attached to the other end. When the piezoelectric diaphragm 31 vibrates, the amount of displacement of the weight via the elastic member 36 increases, so that the vibration is amplified and a strong vibration can be generated.
[0005]
[Patent Document 1]
JP 2000-233157 A (paragraphs 0016 to 0024, FIG. 1)
[0006]
[Problems to be solved by the invention]
A vibration generator using such a piezoelectric element has little loss in electro-mechanical displacement conversion, and seems to be quite promising as a vibration generator for a small electronic device. However, even in the recent rapid spread of mobile phones and technological progress, a vibration generator using the above method has not yet been put into practical use. The reason seems to be that it is practically difficult to obtain a sufficiently large vibration while saving power.
[0007]
The present invention has been made in view of these points, and an object of the present invention is to provide a vibration generator capable of generating a sufficiently large vibration for incoming call notification while suppressing power consumption. Is to provide.
[0008]
[Means for Solving the Problems]
The vibration generator according to the present invention, which has been made to solve the above problems,
a) an electro-mechanical displacement mutual conversion element for converting an electrical signal into mechanical vibration, or vice versa, and converting mechanical vibration into an electrical signal;
b) an elastic member partially or directly connected to the electro-mechanical displacement mutual conversion element;
c) a weight provided at a position away from the connecting portion between the elastic member and the electromechanical displacement mutual conversion element;
d) a support that supports the elastic member at a position away from the weight and propagates vibrations of the elastic member to an object;
e) grasping a vibration state based on an electric signal generated in the electro-mechanical displacement mutual conversion element due to deformation of the electro-mechanical displacement mutual conversion element or displacement of the elastic member or the weight; Control means for supplying power to the electro-mechanical displacement interconversion element so that the vibration is amplified;
The electro-mechanical displacement mutual conversion element is an element that can selectively perform switching between conversion from electrical signal to mechanical vibration and vice versa, and the control means includes A detection period for detecting an electric signal generated in the electro-mechanical displacement mutual conversion element due to the deformation of the electro-mechanical displacement mutual conversion element, and supplying electric power to the electro-mechanical displacement mutual conversion element to cause displacement in the element A drive period is provided in a time-sharing manner, a vibration state is grasped based on an electric signal detected in the detection period, and power is supplied to the element so that the vibration is amplified .
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
In the vibration generating apparatus according to the present invention, the electro-mechanical displacement mutual conversion element is a single element that can be selectively switched by switching between conversion from an electric signal to mechanical vibration and vice versa. And a combination of elements that convert electrical signals into mechanical vibrations and elements that detect mechanical vibrations and convert them into electrical signals for feedback. obtain. A typical example of the former element is a piezoelectric element.
[0011]
As a basic operation when a piezoelectric element is used as an electro-mechanical displacement mutual conversion element, mechanical vibration generated by the piezoelectric element is applied to the elastic member, and the elasticity of the elastic member and the inertia of the weight are determined. Use to amplify vibration. The piezoelectric element utilizes both an inverse piezoelectric effect that causes deformation when a voltage is applied and a piezoelectric effect that generates a voltage when deformation is caused by an external mechanical force due to vibration. However, in the conventional apparatus as described above, a voltage having a predetermined frequency is applied to the piezoelectric element and only vibrates at the frequency, whereas in the apparatus according to the present invention, the excited weight is applied. In accordance with the vibration of the weight, that is, in accordance with the vibration energy direction of the weight, vibration energy is applied to the weight via the elastic member so as to further increase (vibrate) the vibration. In other words, further excitation is adaptively performed according to the vibration state (frequency, phase, magnitude, etc. of vibration).
[0012]
Specifically, the control means detects an electric signal generated in the piezoelectric element due to deformation of the piezoelectric element during the detection period, grasps the vibration state at that time based on this, and accelerates the vibration. A voltage is applied to the piezoelectric element during the driving period so that the piezoelectric element compresses or expands in the direction. By repeating such excitation, the weight accumulates a large amount of energy that cannot be applied by a single excitation, and the vibration is close to the maximum within the range of the strength of the elastic body and other mechanical constraints. Can be obtained.
[0013]
In addition to the piezoelectric element, those that can be used as the electro-mechanical displacement mutual conversion element can be freely deformed such as torsion and expansion / contraction according to changes in applied voltage and supply current, and the energy conversion efficiency thereof. Various materials can be used as long as they are high. For example, a conductive polymer that conducts electricity can be used for the above purpose because it undergoes stretching deformation by an electrochemical oxidation / reduction reaction. Of course, the principle and type of electro-mechanical displacement conversion are not limited as long as the above conditions are satisfied.
[0014]
As described above, according to the vibration generator of the present invention, the vibration energy generated by the electro-mechanical displacement mutual conversion element as the vibration source is efficiently supplied to the weight held by the elastic member. Can get a big vibration. In addition, according to the vibration generator of the present invention, since driving power is not supplied to the electro-mechanical displacement mutual conversion element during the detection period, power consumption can be suppressed as a whole. In addition, since the timing of supplying power to the electro-mechanical displacement mutual conversion element is appropriately controlled so as to amplify the vibration, the vibration can be reliably and efficiently amplified, and quick from the start of the vibration. A large vibration can be generated at the rising edge. In addition, unlike a conventional vibration generator using a motor, it does not have a mechanism that receives a frictional force or the like such as a bearing, so that there is little failure or breakage and high reliability can be achieved.
[0015]
As an embodiment of the vibration generator according to the present invention, the control means recognizes at least a half cycle of the vibration waveform in the detection period and sets a time width for applying voltage based on the recognition. Can do. According to this configuration, the above-described excitation is performed every time the traveling direction of the weight is reversed by the vibration, so that the vibration amplification effect is large and a large vibration can be obtained more quickly.
[0016]
Furthermore, it is more preferable that the control means recognizes the peak of the vibration waveform during the detection period and sets the voltage application start timing after the peak appears. According to such a configuration, even when there are variations in structural size, weight, characteristics, etc. that affect the vibration state of piezoelectric elements, elastic members, weights, etc., or even fluctuations due to the effects of temperature or humidity, Large vibrations can be reliably obtained without any adjustment.
[0017]
【Example】
Hereinafter, a vibration generator according to an embodiment of the present invention will be described with reference to FIGS.
[0018]
FIG. 1 is a schematic overall configuration diagram of a vibration generator according to the present embodiment, FIG. 2 is a conceptual diagram for explaining the vibration principle of the vibration generator, and FIG. 3 is a flowchart showing an example of operation control in the vibration generator. 4 and 5 are schematic waveform diagrams for explaining the operation of the vibration generator.
[0019]
In this vibration generator, a pair of piezoelectric elements 3a and 3b is provided as a vibration source 1 at a substantially central portion of an elongated plate-like arm 2 having elasticity (spring property) so as to sandwich the arm 2 from above and below. The weights 5 are fixed to both ends of the arm 2, respectively. The lower piezoelectric element 3b is fixed to the upper end of the support 4 having rigidity, and the lower end is fixed to a casing 6 such as a mobile phone to be vibrated. When the vibration source 1 vibrates in the vertical direction. Vibration propagates to the housing 6 via the support 4.
[0020]
A piezoelectric element driving unit 10 is connected to the electrode portions of the piezoelectric elements 3a and 3b as an electric circuit. The piezoelectric element driving unit 10 functionally detects the voltage generated at the both end electrodes due to the deformation (strain) due to the compressive force or the expansion force applied to the piezoelectric elements 3a and 3b during a predetermined period, and determines the deformation amount. A deformation amount detection unit 11 to grasp, an arithmetic processing unit 12 that determines a state of vibration based on the deformation amount and determines a voltage application timing, and the like, and applies a drive voltage to the piezoelectric elements 3a and 3b at the determined timing. The voltage generating unit 13 and the control unit 14 that supplies a control signal to each of the above units are configured. The arithmetic processing unit 12 and the control unit 14 can be mainly configured by a microcomputer composed of a CPU, a memory, etc., and by executing predetermined arithmetic programs and control programs on the microcomputer, predetermined processing as described later is performed. Function can be achieved.
[0021]
Next, the operation of the vibration generator having the above configuration will be described. When a voltage having a predetermined cycle is applied from the voltage generator 13 to the piezoelectric elements 3a and 3b, the piezoelectric elements 3a and 3b expand and contract in the vertical direction accordingly. The pair of upper and lower piezoelectric elements 3a and 3b is configured to maintain a relationship in which one of the piezoelectric elements 3a and 3b contracts when the other extends, and the central portion of the arm 2 sandwiched between the piezoelectric elements 3a and 3b is indicated by an arrow M1 in FIG. So that it vibrates up and down. Since the arm 2 has elasticity and an inertial force acts on the weight 5, when the central portion of the arm 2 vibrates up and down as described above, the arm 2 as shown by an arrow M <b> 2 in FIG. 2. Both ends of the housing 6 swing up and down greatly, and the vibration is amplified by the force, and the housing 6 vibrates greatly.
[0022]
The amplitude of the vibration becomes a sine wave as shown in FIG. 4A and gradually increases with time. In general, such a mechanical vibration system has a natural frequency that depends on the elastic coefficient of the arm 2 and the weight of the weight 5, and a conventional vibration generator applies a voltage in the vicinity of this natural frequency to the piezoelectric element. It waits for the vibration to be amplified by the resonance action of the vibration system including the elastic member. On the other hand, in the apparatus of the present embodiment, the vibration state of the weight 5 is grasped, and the piezoelectric elements 3a and 3b are driven so as to positively accelerate the vibration. That is, in order to grasp the actual vibration state, the piezoelectric effect by the piezoelectric elements 3a and 3b is used, and the piezoelectric is adaptively adjusted so that the vibration is further accelerated and the voltage application time is as short as possible. Control is performed to apply a voltage to the elements 3a and 3b.
[0023]
Specifically, as shown in FIG. 3, the control procedure from the start of vibration is sequentially shifted to three stages of an initial excitation mode, a deformation amount detection process, and an adaptive control mode.
[0024]
First, in order to cause vibration from a no-vibration state, an initial excitation mode is set at the beginning of vibration (step S1). That is, the voltage generator 13 applies a pulse voltage having a predetermined frequency to the piezoelectric elements 3a and 3b (see FIG. 4B). Thereby, the vibration generating source 1 including the piezoelectric elements 3a and 3b starts to vibrate. At this time, the frequency may be, for example, a natural frequency of the vibration generation source 1 and may be calculated in advance based on the elastic coefficient and length of the arm 2, the weight of the weight 5, and the like.
[0025]
When a predetermined time (usually very short time) has elapsed from the start of vibration, voltage application by the voltage generation unit 13 is temporarily stopped, and the deformation amount detection unit 11 applies an electrical signal obtained from the piezoelectric elements 3a and 3b. Based on this, a deformation amount is detected (step S2). As shown in FIG. 2, when the arm 2 is vibrating while being bent, the piezoelectric elements 3 a and 3 b are deformed by the compression force or the extension force by the arm 2. Since the piezoelectric elements 3a and 3b generate a voltage corresponding to the deformation amount due to the piezoelectric effect, the deformation amount detection unit 11 detects a temporal change in the deformation amount and sends the data to the arithmetic processing unit 12. .
[0026]
The temporal change in the deformation amount corresponds to a part of the vibration waveform as shown in FIG. Therefore, as shown in FIG. 5C, the temporal change of the deformation amount is monitored continuously (actually every minute time interval) during the period of time t1 set to be equal to or longer than the period of the half cycle t of vibration. Thus, the positive and negative peaks Pa and Pb of the vibration waveform can be detected, and the time t required from one peak to the other peak (in the example of FIG. 5, from the negative peak Pa to the positive peak Pb) is also detected. can do.
[0027]
After the deformation amount at that time can be detected in this way, the mode shifts to the adaptive control mode (step S3). The vibration amplitude peaks Pa and Pb are points where the vibration direction is reversed. Therefore, if the piezoelectric elements 3a and 3b are driven in the direction of accelerating the vibration immediately after the peak appears and the voltage application is stopped just before the next peak appears, the reverse piezoelectric effect of the piezoelectric elements 3a and 3b occurs. The compression / extension operation does not deviate from the vibration direction of the arm 2 at that time, and appropriate vibration amplification can be performed.
[0028]
Therefore, the arithmetic processing unit 12 determines a time width t2 for applying the voltage next based on the time t acquired immediately before the calculation processing unit 12, and accelerates the vibration of the arm 2 from a point when a little has elapsed after the peak appears. A pulse voltage having the time width t2 is applied to drive the piezoelectric elements 3a and 3b. As a result, the movement of the arm 2 is accelerated, but the voltage becomes zero before the next peak. Instead, the deformation amount detection unit 11 detects the deformation amount and grasps the vibration waveform in the same manner as described above. Since it is before the peak at the start of deformation amount detection, when the vibration waveform is monitored, it can be recognized that the vibration direction of the arm 2 has been reversed beyond the peak. Therefore, when a little has passed after exceeding the peak, the detection of the deformation amount is stopped, and a pulsed voltage having the time width t2 is applied to drive the piezoelectric elements 3a and 3b in the direction of accelerating the vibration of the arm 2. Apply. It is more preferable that the time width of the voltage to be applied next is appropriately adjusted according to the time t3 from when the deformation amount detection is started until the peak actually appears.
[0029]
In this way, during a predetermined period before and after the positive and negative peaks of the vibration waveform, the application of voltage to the piezoelectric elements 3a and 3b is stopped, and instead the deformation waveform is detected to grasp the vibration waveform, and the peak Make sure of the position of In a period suitable for accelerating the vibration of the arm 2 on the way from one peak to the other peak, a voltage is reliably applied to the piezoelectric elements 3a and 3b to accelerate the vibration.
[0030]
By doing so, the piezoelectric elements 3a and 3b can be driven so as to synchronize with the vibration of the weight 5 and accelerate the moving speed in accordance with the moving direction. In general, the displacement of a piezoelectric element is not necessarily large, but the response is good and the vibration energy that can be given to the outside is large. Therefore, large vibration energy can be supplied to the weight 5 via the arm 2 every time the piezoelectric elements 3a and 3b are driven. By repeating such excitation, vibration energy is accumulated in the weight 5, and for example, the vibration can be gradually increased so as to spread the swing, and a strong vibration with a large amplitude can be obtained. Further, in this vibration generator, the period during which the drive voltage is applied to the piezoelectric elements 3a and 3b can be suppressed to about 60 to 80% of the whole, so that the power consumption can be reduced.
[0031]
Note that the above embodiment is merely an example of the present invention, and it is obvious that modifications and corrections can be made as appropriate without departing from the scope of the claims. Specifically, for example, the arm 2 is not extended to both sides of the support 4 but can be modified to have a structure in which the support 4 is provided at one end of the arm 2 and the weight 5 is provided at the other end. Can easily be conceived. The drive control procedure described above is an example, and the gist of the present invention is that not only the inverse piezoelectric effect of the piezoelectric element but also the piezoelectric effect is used in a time-sharing manner in order to effectively amplify the vibration. is there.
[Brief description of the drawings]
FIG. 1 is a schematic overall configuration diagram of a vibration generator according to an embodiment of the present invention.
FIG. 2 is a conceptual diagram for explaining the vibration principle of the vibration generator according to the present embodiment.
FIG. 3 is a flowchart showing an example of operation control in the vibration generator according to the present embodiment.
FIG. 4 is a schematic waveform diagram for explaining the operation of the vibration generator according to the present embodiment.
FIG. 5 is a schematic waveform diagram for explaining the operation of the vibration generator according to the present embodiment.
FIG. 6 is a schematic configuration diagram of a vibration generator using a piezoelectric element, which is conventionally known.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vibration source 2 ... Arm 3a, 3b ... Piezoelectric element 4 ... Support body 5 ... Weight 6 ... Case 10 ... Piezoelectric element drive part 11 ... Deformation amount detection part 12 ... Arithmetic processing part 13 ... Voltage generation part 14 ... Control unit

Claims (3)

a) an electro-mechanical displacement mutual conversion element for converting an electrical signal into mechanical vibration, or vice versa, and converting mechanical vibration into an electrical signal;
b) an elastic member partially or directly connected to the electro-mechanical displacement mutual conversion element;
c) a weight provided at a position away from the connecting portion between the elastic member and the electromechanical displacement mutual conversion element;
d) a support that supports the elastic member at a position away from the weight and propagates vibrations of the elastic member to an object;
e) grasping a vibration state based on an electric signal generated in the electro-mechanical displacement mutual conversion element due to deformation of the electro-mechanical displacement mutual conversion element or displacement of the elastic member or the weight; Control means for supplying power to the electro-mechanical displacement interconversion element so that the vibration is amplified;
The electro-mechanical displacement mutual conversion element is an element that can selectively perform switching between conversion from electrical signal to mechanical vibration and vice versa, and the control means includes A detection period for detecting an electric signal generated in the electro-mechanical displacement mutual conversion element due to the deformation of the electro-mechanical displacement mutual conversion element, and supplying electric power to the electro-mechanical displacement mutual conversion element to cause displacement in the element A vibration generating apparatus characterized in that a drive period is provided in a time-sharing manner, a vibration state is grasped based on an electric signal detected in the detection period, and electric power is supplied to the element so that the vibration is amplified. 2. The vibration generating apparatus according to claim 1 , wherein the control unit recognizes at least a half cycle of a vibration waveform in the detection period and sets a time width for applying a voltage based on the recognition. Said control means, said recognizing the peak of the vibration waveform in the detection period, the vibration generator according to claim 1 or 2, characterized in that setting the start timing of the voltage application after the peak appeared.

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