JP2019066301A - Communication terminal - Google Patents

Abstract

To provide a communication terminal with which it is possible to secure the acceleration detection accuracy of an acceleration sensor.SOLUTION: A stiction detection unit 29 acquires the absolute value Sk' of an acceleration value from an acceleration sensor 10 and compares the absolute value Sk' with a previously acquired value. The stiction detection unit 29 determines that there is occurrence of a stiction in the acceleration sensor 10 when the previous and latest absolute values Sk' of acceleration are the same. When a stiction is detected, a stiction elimination unit 30 forcibly moves an electrode that is a device 12 element of the acceleration sensor 10 and thereby gets rid of the stiction having occurred in the acceleration sensor 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication terminal provided with an acceleration sensor.

  Conventionally, as a communication terminal of this type, an electronic key provided with an acceleration sensor is known (see Patent Document 1 etc.). The electronic key provided with the acceleration sensor is switched to the activated state, for example, when the acceleration sensor detects the movement (vibration) of the electronic key. In this way, the power consumption of the electronic key battery can be reduced. This also serves as a countermeasure against unauthorized use of the vehicle by operating the vehicle by illegally connecting the communication between the electronic key and the vehicle with the relay.

Unexamined-Japanese-Patent No. 2006-63676

  By the way, in this type of acceleration sensor, there is a possibility that stiction may occur in which an electrode which is a component of the acceleration sensor is fixed. If stiction occurs in the acceleration sensor, a correct output can not be obtained from the acceleration sensor, and there is a problem that the detection accuracy of the movement of the electronic key is deteriorated.

  An object of the present invention is to provide a communication terminal capable of ensuring the accuracy of acceleration detection of an acceleration sensor.

  A communication terminal for solving the above problems is characterized in that, in a configuration in which the operation is controlled by a terminal control unit provided in the terminal body based on an output of an acceleration sensor that detects a movement occurring in the terminal body, A stiction detection unit for detecting stiction, which is a kind of operation failure, and a stiction cancellation unit for executing an operation for canceling the stiction when the stiction is detected.

  According to this configuration, stiction which may occur in the acceleration sensor can be detected, and when stiction is detected, processing for canceling the stiction is executed. For this reason, even if stiction occurs in the acceleration sensor, it is possible to take measures to return the acceleration sensor to the original state without stiction. Therefore, it is possible to secure the accuracy of the detection signal of the acceleration sensor.

  In the communication terminal, preferably, the stiction detection unit determines whether stiction occurs in the acceleration sensor based on an absolute value of acceleration data input from the acceleration sensor. According to this configuration, the presence or absence of stiction is determined using the absolute value of the acceleration detected by the acceleration sensor, which is advantageous for securing the detection accuracy of the stiction.

  In the communication terminal, the acceleration sensor detects the movement of the electrode by the detection unit to detect the movement generated in the terminal body, and the stiction cancellation unit forces the electrode at the time of detection of stiction. It is preferable to eliminate the stiction by moving it in a stationary manner. According to this configuration, at the time of stiction detection, stiction is eliminated through measures for directly moving the electrodes of the acceleration sensor. Therefore, it becomes possible to eliminate stiction more reliably.

  The communication terminal further includes a self test function unit that executes a self test that periodically checks whether the acceleration sensor operates normally, and the stiction canceling unit performs the self test when stiction is detected. It is preferable to eliminate the stiction by operating the functional unit. According to this configuration, it is possible to eliminate stiction of the acceleration sensor, for example, by using the self-test function that has been installed before the communication terminal. There is no need.

  According to the present invention, it is possible to secure the accuracy of the acceleration detection of the acceleration sensor.

The block diagram of the communication terminal (electronic key) of one embodiment. The schematic block diagram of the device of an acceleration sensor. It is a wave form diagram of the acceleration detected by an acceleration sensor, Comprising: (a) is a wave form diagram at the time of normal, (b) is a wave form diagram at the time of stiction generation | occurrence | production. The flowchart showing a series of flows from detection of stiction to cancellation.

Hereinafter, an embodiment of the communication terminal will be described according to FIGS. 1 to 4.
As shown in FIG. 1, the communication terminal 1 is an electronic key 3 that performs key verification wirelessly with the vehicle 2. The electronic key 3 has a terminal control unit 4 for controlling the operation of the electronic key 3, an antenna 5 for communicating radio waves in the electronic key 3, and a memory 6 in which an electronic key ID which is a unique ID of each electronic key 3 is registered. Equipped with The electronic key 3 executes communication of ID collation with the vehicle 2 triggered by communication from the electronic key 3 or smart key (registered trademark) that executes communication of ID collation with the vehicle 2 triggered by communication from the vehicle 2 It may be any of the wireless keys. The antenna 5 preferably receives radio waves in the LF (low frequency) band in reception, and transmits radio waves in the UHF (ultra high frequency) band in transmission.

  In the case of the smart key, when the electronic key 3 receives a radio wave (for example, a wake signal) transmitted from the vehicle 2, the electronic key 3 switches from the standby state to the activated state. The electronic key 3 switched to the activated state executes ID verification (smart verification) with the vehicle 2. The smart verification includes, for example, electronic key ID verification for confirming whether the electronic key ID registered in the electronic key 3 is correct or not, and challenge response authentication which is a type of encrypted communication. If smart verification (smart verification outside the vehicle) is established between the electronic key 3 located outside the vehicle and the vehicle 2, locking and unlocking of the vehicle door is permitted or executed. When smart verification is established between the electronic key 3 located in the vehicle and the vehicle 2, the power transition operation by the engine switch in the vehicle is permitted.

  The standby state of the electronic key 3 is, for example, a state in which the power is supplied to only a part of the electrical components of the electronic key 3 so that the power is supplied only to the communication circuit of the antenna 5 of the electronic key 3 or the like. Say. In addition, the activation state of the electronic key 3 refers to a state in which power is supplied to all the electrical components of the electronic key 3.

  When the electronic key 3 is a wireless key, when an operation button (not shown) provided on the electronic key 3 is operated, the electronic key 3 transmits a key radio wave corresponding to the operation button. The operation buttons include, for example, a lock button operated when locking the vehicle door, and an unlock button operated when unlocking the vehicle door. When the vehicle 2 receives the key radio wave from the electronic key 3, the vehicle 2 collates the electronic key ID contained therein, and if the collation is established, the vehicle 2 operates according to the command contained in the same radio wave to lock and unlock the vehicle door.

  The electronic key 3 has a power saving function for reducing the consumption of the battery mounted on the electronic key 3. In this case, the electronic key 3 is provided with an acceleration sensor 10 that detects a movement generated in the terminal body 9. The acceleration sensor 10 includes a sensor control unit 11 that controls the operation of the acceleration sensor 10, and a device 12 that is a place to measure movement (vibration) in the acceleration sensor 10. The sensor control unit 11 is, for example, a dedicated ASIC. The device 12 is, for example, a MEMS (Micro Electro Mechanical Systems).

  The electronic key 3 includes a power saving function unit 15 that controls the power saving function of the electronic key 3. The power saving function unit 15 is provided in the terminal control unit 4. The power saving function unit 15 detects a motion generated in the electronic key 3 based on the vibration detection signal Sa input from the acceleration sensor 10. The vibration detection signal Sa is preferably a binary code in which the signal levels of Hi and Low change, for example, when vibration is detected. When the power saving function unit 15 detects that movement (vibration) occurs in the electronic key 3, the power saving function unit 15 puts the electronic key 3 in a communicable state (for example, a standby state or a start state). On the other hand, when detecting that no movement (vibration) has occurred in the electronic key 3, the power saving function unit 15 puts the electronic key 3 in the power saving state (power off state). The power saving state is realized, for example, by executing the power saving sequence written in the memory 6.

  As shown in FIG. 2, when the vibration detection structure of the acceleration sensor 10 is a “three-axis structure”, the device 12 includes detection units 18 on each of the X axis, the Y axis, and the Z axis. In this example, the X-axis detection unit 18 is "18a", the Y-axis detection unit 18 is "18b", and the Z-axis detection unit 18 is "18c". Each detection unit 18 is constructed from a detection element 19 which detects the movement occurring in the electronic key 3 in each axis. The detection element 19 includes an electrode 20 whose conduction is controlled by the sensor control unit 11 and a detection unit 21 which detects a capacitance generated in the electrode 20. The electrode 20 of this embodiment moves in response to the vibration of the electronic key 3 with respect to the fixed frame portion 22, and in the case of this embodiment, swings with respect to the fulcrum 23. Further, a pair of detection units 21 in this example is disposed on both sides of the swinging electrode 20, and detects the capacitance according to the inclination of the electrode 20.

  When movement occurs in the electronic key 3, the electrodes 20 of each axis swing so as to have an inclination according to the movement. At this time, the detection unit 21 of each axis detects the capacitance according to the inclination of the electrode 20. Then, the sensor control unit 11 inputs the value of the capacitance detected by the detection unit 21 of each axis as the value of the acceleration generated to the electronic key 3, and is movement of the electronic key 3 generated from this acceleration? Decide whether or not. When confirming that movement has occurred in the electronic key 3 through such processing, the sensor control unit 11 outputs a vibration detection signal Sa indicating the presence of movement to the terminal control unit 4.

  Returning to FIG. 1, the electronic key 3 has a self test function (fault detection function) that periodically checks whether the acceleration sensor 10 operates properly. In this case, the electronic key 3 includes a self test function unit 26 that controls the self test function of the electronic key 3. The self test function unit 26 carries out a self test at a prescribed timing, and more specifically, the electrode 20 is energized to force the electrode 20 to move. At this time, if the acceleration sensor 10 is normal, the electrode 20 moves, and the acceleration detected by the device 12 changes. Therefore, if the self test function unit 26 can confirm the input of the vibration detection signal Sa indicating that there is a motion at the time of the self test, it determines that the acceleration sensor 10 is normal, and performs various processes using the output of the acceleration sensor For example, the power saving function etc. is executed as usual.

  On the other hand, the self-test function unit 26 determines that the acceleration sensor 10 is not normal if the input of the vibration detection signal Sa indicating the presence of movement can not be confirmed at the time of the self-test. At this time, the terminal control unit 4 (electronic key 3) disconnects the acceleration sensor 10 and operates the electronic key 3. That is, the terminal control unit 4 (electronic key 3) disconnects the acceleration sensor 10 from the operation of the process and executes a process that does not use the output of the acceleration sensor 10.

  By the way, in this type of acceleration sensor 10, there is a possibility that a so-called "stiction" may occur, for example, in which the electrode 20 is stuck. When stiction occurs in the acceleration sensor 10, the electrode 20 does not move despite movement of the electronic key 3, and an appropriate acceleration according to the vibration of the electronic key 3 is not output from the acceleration sensor 10. It becomes a situation. This example is a technique for solving this problem.

  In the case of this example, the electronic key 3 includes a stiction detection unit 29 that detects stiction, which is a type of malfunction of the acceleration sensor 10. The stiction detection unit 29 is provided in the terminal control unit 4. The stiction detection unit 29 acquires a detection signal Sk, which is acceleration data (acceleration value) detected by the acceleration sensor 10, as an "absolute value Sk '", and detects the presence or absence of stiction based on the absolute value Sk'. Do. The stiction detection unit 29 determines that stiction does not occur if a change occurs in the absolute value Sk ′ of acceleration, and if a change occurs in the absolute value Sk ′ of an acceleration, stiction occurs. Judge that it has occurred.

  The electronic key 3 includes a stiction canceling unit 30 that executes an operation for canceling the stiction when the stiction is detected. The stiction cancellation unit 30 is provided in the terminal control unit 4. It is preferable that the stiction canceling unit 30 of this example cancels stiction by operating the self test function unit 26 at the time of detection of stiction. That is, at the time of detection of stiction, the stiction canceller 30 forcibly moves the electrode 20 to cancel stiction.

Next, the operation and effects of the communication terminal 1 (electronic key 3) according to the present embodiment will be described according to FIGS. 3 and 4. FIG.
The output waveform of the acceleration sensor 10 at the normal time is illustrated in FIG. As can be seen from the figure, if the acceleration sensor 10 is normal, the value (absolute value Sk ') of the detection signal Sk of the acceleration sensor 10 also changes according to the movement generated in the electronic key 3. Thus, if the output of the acceleration sensor 10 constantly fluctuates, the acceleration sensor 10 should be regarded as normal.

  On the other hand, FIG. 3B shows the output waveform of the acceleration sensor 10 at the time of stiction generation. As can be understood from the figure, when stiction occurs in the acceleration sensor 10, the value (absolute value Sk ') of the detection signal Sk of the acceleration sensor 10 is fixed at a constant value. Therefore, if the output of the acceleration sensor 10 is constant, it can be considered that stiction occurs in the acceleration sensor 10. This example uses this principle to detect the presence or absence of stiction.

  Subsequently, according to the flowchart of FIG. 4, a series of flows from detection of stiction to cancellation will be described. The flowchart of FIG. 6 is repeatedly executed at the sampling timing of the output of the acceleration sensor 10.

  In step 101, the stiction detection unit 29 acquires an absolute value Sk ′ of acceleration from the acceleration sensor 10 after a predetermined time has elapsed, and stores the value in the memory 6. In addition, it is preferable that the fixed time described here is the sampling timing of the acceleration at the time of detecting the presence or absence of movement, such as a vibration, by the acceleration sensor 10, for example.

  In step 102, the stiction detecting unit 29 determines whether or not there is a difference with respect to the previously acquired absolute value Sk 'of acceleration. That is, it is confirmed whether the absolute value Sk 'of the acceleration acquired by this and the last time becomes the same (or approximation). Here, if there is no difference in absolute value Sk 'of acceleration between the last time and this time, the process proceeds to step 103, and if there is a difference in absolute value Sk' of acceleration between the last time and this time, the process proceeds to step 106.

  In step 103, the terminal control unit 4 determines whether the acceleration sensor 10 detects a motion such as a vibration. Here, the terminal control unit 4 determines whether or not the vibration detection signal Sa is input from the acceleration sensor 10. Then, if the acceleration sensor 10 detects a motion such as vibration, the process proceeds to step 104, and if the acceleration sensor 10 does not detect a motion such as vibration, the process proceeds to step 105.

  In step 104, the terminal control unit 4 maintains the communicable state of the electronic key 3 when the acceleration sensor 10 detects a motion such as vibration. As a result, since the electronic key 3 is in the standby state or in the activated state, it is possible to execute communication of ID collation with the vehicle 2 through wireless communication.

  On the other hand, in step 105, when the acceleration sensor 10 does not detect a motion such as vibration, the terminal control unit 4 shifts the execution application of the electronic key 3 to the power saving sequence. As a result, the power saving function unit 15 operates and the electronic key 3 shifts to the power saving state, so power saving of the battery of the electronic key 3 becomes possible.

  In addition, in step 106, when there is no difference in absolute value Sk 'of acceleration between the previous time and the current time, the stiction cancellation unit 30 performs a self test and generates in the acceleration sensor 10 (electrode 20). Eliminate stiction. In the case of this example, the stiction canceling unit 30 cancels the stiction generated in the acceleration sensor 10 using the self-test function that is conventionally mounted on the electronic key 3.

  Specifically, the stiction elimination unit 30 forcibly moves the electrode 20 by applying a predetermined voltage to the electrode 20 to eliminate stiction. Thereby, the electrode 20 returns to the original normal state, and it becomes possible to detect the movement generated in the electronic key 3 as usual. Therefore, various processes (for example, a power saving function and the like) using the output of the acceleration sensor 10 can be correctly executed.

  Now, in the case of the present example, stiction which may occur in the acceleration sensor 10 can be detected, and at the time of stiction detection, processing for eliminating the stiction (in the present example, a self test function) is executed. For this reason, even if stiction occurs in the acceleration sensor 10, it is possible to implement measures to return the acceleration sensor 10 to the original state without stiction. Therefore, the accuracy of the acceleration detection of the acceleration sensor 10 can be secured.

  The stiction detection unit 29 determines whether stiction occurs in the acceleration sensor 10 based on the absolute value Sk ′ of the acceleration data input from the acceleration sensor 10. Therefore, since the presence or absence of stiction is determined using the absolute value Sk 'of the acceleration detected by the acceleration sensor 10, it is advantageous for securing the detection accuracy of the stiction.

  The acceleration sensor 10 detects the movement of the terminal 20 by detecting the movement of the electrode 20 by the detection unit 21. The stiction cancellation unit 30 cancels stiction by forcibly moving the electrode 20 at the time of detection of stiction. For this reason, at the time of stiction detection, stiction is eliminated through measures for moving the electrodes 20 of the acceleration sensor 10 directly. Therefore, stiction can be eliminated more reliably.

  The stiction canceling unit 30 cancels the stiction by operating the self test function unit 26 provided in advance in the electronic key 3 when detecting the stiction. Therefore, it is possible to eliminate stiction of the acceleration sensor 10 by using the self-test function that has been installed since the electronic key 3. Therefore, there is no need to add significant functions to eliminate stiction. .

The embodiment is not limited to the configuration described above, and may be changed to the following modes.
The process of using the acceleration sensor 10 in the electronic key 3 is a power saving function that stops the operation of the electronic key 3 when the electronic key 3 does not move, and unauthorized communication prevention that prevents unauthorized communication establishment using a relay It is not limited to being used for a function etc. For example, the movement (motion movement) applied to the electronic key 3 may be determined from the output of the acceleration sensor 10, and the vehicle 2 may be made to perform an operation according to the movement movement. For example, when the operation of opening the power slide door of the vehicle 2 is detected by the acceleration sensor 10, a radio wave to that effect is transmitted from the electronic key 3 to the vehicle 2, and the power slide door is automatically opened. Good.

In the case of taking the difference of the absolute value Sk 'of acceleration, for example, the difference of the moving average which is the average of the absolute value Sk' obtained by tracing back a predetermined number of samples from the present may be taken.
The difference between the absolute value Sk 'of the acceleration is not limited to the difference from the immediately preceding absolute value Sk', and may be, for example, a comparison value with the absolute value Sk 'sampled a predetermined number of times earlier.

The method of detecting stiction is not limited to the method of detecting based on the absolute value Sk ′ acquired from the acceleration sensor 10, and may be appropriately changed to various other methods.
The cancellation of stiction is not limited to the method using the self test function. For example, the stiction may be canceled by transitioning to a dedicated stiction cancellation sequence.

The method of eliminating stiction is not limited to the method of forcibly moving the electrode 20, and may be changed to another method such as vibrating the device 12 itself.
The power saving function may determine whether movement such as vibration has occurred in the electronic key 3 based on acceleration data (actual value) acquired from the acceleration sensor 10, for example.

The terminal body 9 refers to, for example, a body portion including the housing of the electronic key 3.
The vibration detection signal Sa and the detection signal Sk may be input to the terminal control unit 4 through different wires.

The structure of the acceleration sensor 10 may be changed as appropriate to the structure described in the embodiment.
The communication terminal 1 may be changed to a terminal other than the electronic key 3.
Next, technical ideas that can be grasped from the above-described embodiment and another example will be additionally described below together with their effects.

  (A) In the communication terminal, based on the vibration detection signal input from the acceleration sensor, it is confirmed whether movement occurs in the terminal body, and the movement is not generated in the terminal body, By shifting the processing of the terminal control unit to the power saving sequence, a power saving function unit is provided to reduce the power consumption of the power supply. According to this configuration, it is possible to save power of the power supply of the communication terminal.

  DESCRIPTION OF SYMBOLS 1 ... Communication terminal, 3 ... Electronic key, 4 ... Terminal control part, 9 ... Terminal main body, 10 ... Acceleration sensor, 20 ... Electrode, 21 ... Detection part, 26 ... Self-test function part, 29 ... Stiction detection part, 30 ... Stiction cancellation unit, Sa ... Vibration detection signal, Sk ... Detection signal, Sk '... Absolute value.

Claims (4)

In a communication terminal whose operation is controlled by a terminal control unit provided in the terminal main body based on an output of an acceleration sensor that detects a movement generated in the terminal main body,
A stiction detection unit that detects stiction, which is a type of malfunction of the acceleration sensor;
A communication terminal comprising: a stiction cancellation unit configured to execute an operation for canceling the stiction when the stiction is detected. The communication terminal according to claim 1, wherein the stiction detection unit determines whether stiction occurs in the acceleration sensor based on an absolute value of acceleration data input from the acceleration sensor. The acceleration sensor detects the movement generated in the terminal main body by detecting the movement of the electrode by a detection unit,
The communication terminal according to claim 1, wherein the stiction cancellation unit cancels the stiction by forcibly moving the electrode when detecting stiction. It has a self test function unit that executes a self test that periodically checks whether the acceleration sensor operates properly.
The communication terminal according to any one of claims 1 to 3, wherein the stiction cancellation unit cancels the stiction by operating the self test function unit at the time of detection of stiction.