Wireless transmitter

Abstract

To secure radio wave transmission at necessary timing while suppressing power consumption.SOLUTION: A wireless transmitter comprises: an acceleration sensor for sequentially detecting acceleration acting on itself and sequentially deriving an acceleration detection value (DET); a transmission circuit constituted to be capable of transmitting a radio wave; and a control circuit constituted so as to control the operation of the transmitter on the basis of the acceleration detection value. The control circuit provides alternately, in a target period (P1-P3) where the acceleration detection value is larger than a threshold, an on period in which a radio wave is transmitted from the transmission circuit and an off period in which radio wave transmission from the transmission circuit is halted, and thereby adjusting the length of each off period according to the detection acceleration value.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to a wireless transmitter.

Background Art

[0002] Remote access devices for remotely unlocking a door when a user approaches a vehicle or the like are widespread. A wireless transmitter is provided in the remote access device. An acceleration sensor (see Patent Document 1) may be provided in the wireless transmitter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] [Summary] Transmitting radio waves in a wireless transmitter involves power consumption. In a wireless transmitter, there is a need for a technology that suppresses unnecessary radio wave transmission as much as possible while ensuring radio wave transmission at the required timing.

[0005] A wireless transmitter according to an aspect of the present disclosure includes an acceleration sensor configured to sequentially detect an acceleration acting on itself and sequentially derive an acceleration detection value, a transmission circuit configured to be able to transmit radio waves, and a control circuit configured to control the operation of the transmitter based on the acceleration detection value. The control circuit alternately provides an on period in which the radio waves are transmitted from the transmission circuit and an off period in which the transmission of the radio waves from the transmission circuit is stopped during a target period in which the acceleration detection value is greater than a threshold value, and adjusts the length of each off period according to the detected acceleration value.

Brief Description of the Drawings

[0006]

Figure 1

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[0007] [Detailed Description] Hereinafter, examples of embodiments of the present disclosure will be specifically described with reference to the drawings. In each of the drawings to be referred to, the same parts are denoted by the same reference numerals, and redundant descriptions regarding the same parts are omitted in principle. In this specification, for the sake of simplicity of description, the name of information, signal, physical quantity, functional unit, circuit, element, or component, etc. corresponding to the symbol or code may be omitted or abbreviated by writing the symbol or code referring to the information, signal, physical quantity, functional unit, circuit, element, or component, etc.

[0008] In the present specification, when any two physical quantities to be compared are physical quantities v1 and v2, "v1 > v2" represents that physical quantity v1 is greater than physical quantity v2, "v1 < v2" represents that physical quantity v1 is smaller than physical quantity v2, and "v1 = v2" represents that the value of physical quantity v1 is the same as the value of physical quantity v2.

[0009] FIG. 1 shows the relationship among a remote access device 1 (hereinafter, may be simply abbreviated as device 1), a user U1, and a vehicle CR according to an embodiment of the present disclosure. The user U1 is a person who possesses the device 1. The device 1 moves along with the movement of the user U1.

[0010] FIG. 2 shows a schematic internal configuration of the device 1. The device 1 has a wireless transmitter 2 capable of transmitting a radio wave WV. A lock management device 3 is provided in the vehicle CR, and the lock management device 3 controls the state of the vehicle CR to a locked state or an unlocked state. The lock management device 3 can generally set the state of the vehicle CR to the locked state. By the cooperation of the device 1 and the lock management device 3, it is detected using the radio wave WV whether the device 1 (and thus the user U1) is close to the vehicle CR.

[0011] The radio wave WV includes an unlocking signal for shifting the state of the object from the locked state to the unlocked state. The user U1 cannot access the object when the object is in the locked state, and can access the object when the object is in the unlocked state. In the configuration of FIG. 1, the vehicle CR is an example of the object, and thus the radio wave WV includes an unlocking signal for shifting the state of the vehicle CR from the locked state to the unlocked state.

[0012] The vehicle CR is provided with a door DR, and the door DR is controlled to be in a locked state or an unlocked state by the lock management device 3. The door DR is an object that separates the internal space (passenger compartment) of the vehicle CR from the external space of the vehicle CR. When the vehicle CR is in the locked state, the door DR is in the locked state. When the vehicle CR is in the unlocked state, the door DR is in the unlocked state. For the user U1 to be able to access the vehicle CR as the object, it means that the user U1 can enter the internal space of the vehicle CR from the external space of the vehicle CR through the door DR. That is, the unlocked state of the vehicle CR refers to a state in which it is possible for the user U1 to enter from the external space of the vehicle CR into the internal space of the vehicle CR, and the locked state of the vehicle CR refers to a state in which such entry is not possible.

[0013] More specifically, when the door DR is in the unlocked state, the user U1 can open and close the door DR. For the door DR to be able to be opened and closed means that the user U1 can freely change the state of the door DR between the open state and the closed state. When the door DR is in the unlocked state, the user U1 can enter the internal space (passenger compartment) of the vehicle CR from the external space of the vehicle CR through the open door DR. When the door DR is in the locked state, the user U1 cannot open and close the door DR. That is, when the door DR is in the locked state, the door DR is fixed in the closed state by the lock management device 3, and the user U1 cannot enter the internal space (passenger compartment) of the vehicle CR from the external space of the vehicle CR through the door DR. Incidentally, the door DR itself may be considered as the object. In this case, the locked state and the unlocked state of the door DR correspond to the locked state and the unlocked state of the object, respectively.

[0014] The lock management device 3 has a receiving circuit (not shown). When a radio wave WV is received by the receiving circuit, based on the unlocking signal in the radio wave WV, the lock management device 3 shifts the state of the vehicle CR from the locked state to the unlocked state. The range where the radio wave WV reaches is limited. The distance between the device 1 and the vehicle CR (specifically, the receiving circuit in the lock management device 3) is referred to as the distance d. When the distance d is a predetermined radio wave reach distance d THWhen the radio wave WV is transmitted from the wireless transmitter 2 under the following conditions, the radio wave WV is received by the receiving circuit of the lock management device 3 (therefore, the above unlocking signal is received). When the distance d exceeds the radio wave reach distance d TH If the radio wave WV is transmitted from the wireless transmitter 2 when it exceeds, in principle, the radio wave WV is not received by the receiving circuit of the lock management device 3 (therefore, the above unlocking signal is not received). However, when the distance d is slightly larger than the radio wave reach distance d TH If the radio wave WV is transmitted from the wireless transmitter 2 when it is slightly larger, the radio wave WV may be received by the receiving circuit of the lock management device 3.

[0015] It can also be expressed as follows. "When d ≤ d TH ", if the radio wave WV is transmitted from the wireless transmitter 2, the radio wave WV is received by the receiving circuit of the lock management device 3. "When d TH < d ≤ d TH2 ", when the radio wave WV is transmitted from the wireless transmitter 2, the radio wave WV may or may not be received by the receiving circuit of the lock management device 3. "When d TH2 < d", if the radio wave WV is transmitted from the wireless transmitter 2, the radio wave WV is not received by the receiving circuit of the lock management device 3. Here, the distance d TH2 is larger than the radio wave reach distance d TH .

[0016] In addition, the device 1 is provided with various operation buttons and an internal power supply circuit (not shown) in addition to the wireless transmitter 2. A battery composed of a primary battery or a secondary battery is mounted on the device 1, and an internal power supply voltage is generated by the internal power supply circuit based on the output voltage of the battery. The wireless transmitter 2 is driven based on the internal power supply voltage. Also, functions such as starting the engine of the vehicle CR based on the radio wave WV may be provided in the device 1 and the lock management device 3, but hereinafter, only the function of controlling the door DR to the locked state or the unlocked state will be noted.

[0017] As shown in FIG. 2, the wireless transmitter 2 includes an acceleration sensor 10, a host circuit 20, and a transmission circuit 30. The host circuit 20 includes a control circuit 21 and a state machine 22. In FIG. 2, the control circuit 21 and the state machine 22 are shown separately, but the state machine 22 may be incorporated in the control circuit 21.

[0018] The acceleration sensor 10 detects acceleration. The acceleration detected by the acceleration sensor 10 is the acceleration acting on the acceleration sensor 10 and is also the acceleration acting on the device 1 and the wireless transmitter 2. The user U1 moves or remains stationary while wearing the device 1. For example, the user U1 moves or remains stationary while holding the device 1 in the hand, putting the device 1 in the pocket of his / her clothing, or putting the device 1 in the bag he / she carries. Therefore, the acceleration corresponding to the behavior of the user U1 is detected by the acceleration sensor 10, and typically, it may be considered that the acceleration of the user U1 is detected by the acceleration sensor 10.

[0019] In the acceleration sensor 10, an X-axis, a Y-axis, and a Z-axis are defined. The X-axis, the Y-axis, and the Z-axis are three mutually orthogonal axes. The acceleration sensor 10 is disposed at the origin where the X-axis, the Y-axis, and the Z-axis intersect. The acceleration sensor 10 is a three-axis acceleration sensor that detects the respective accelerations in the X-axis, Y-axis, and Z-axis directions. A vector based on the detection result of the acceleration sensor 10 is called an acceleration vector. The X-axis, Y-axis, and Z-axis components of the acceleration vector are the X-axis, Y-axis, and Z-axis components of the acceleration detected by the acceleration sensor 10, respectively. The magnitude of the acceleration vector is called an acceleration detection value DET. The acceleration sensor 10 repeatedly executes an acceleration detection operation of detecting the acceleration acting on the device 1 and deriving the acceleration detection value DET at a predetermined detection period. That is, the acceleration sensor 10 sequentially detects the acceleration acting on itself, the device 1, or the wireless transmitter 2 and sequentially derives the acceleration detection value DET.

[0020] Since the device 1 and the user U1 are assumed to be located on the earth, the gravitational acceleration due to the weight of the earth always acts on the device 1. Although the relationship between the X-axis, Y-axis, and Z-axis and the direction of the gravitational acceleration is indefinite, it is assumed that the above acceleration vector is a vector from which the component of the gravitational acceleration has been excluded. Therefore, the acceleration detection value DET represents the detection value of the acceleration from which the component of the gravitational acceleration has been excluded among the accelerations acting on the device 1. Since the component of the gravitational acceleration is a DC component, the component of the gravitational acceleration can be easily removed by a known method using a filter or the like.

[0021] The acceleration sensor 10 and the host circuit 20 are connected in a manner that enables two-way communication (electrically connected). The acceleration sensor 10 monitors whether a predetermined interrupt condition is satisfied, and when the interrupt condition is satisfied, it sends an interrupt request signal REQ INT to the host circuit 20.

[0022] The operating modes of the host circuit 20 (hereinafter simply referred to as the operating mode) are a standby mode and a normal mode. The host circuit 20 sets the operating mode to the standby mode or the normal mode. It may be considered that a mode setting circuit (not shown) for setting the operating mode of the host circuit 20 to the standby mode or the normal mode is provided in the device 1 separately from the host circuit 20. The host circuit 20 includes an interrupt monitoring circuit that monitors the reception of the interrupt request signal REQ INT and a main circuit which is the other circuit. In the standby mode, only the interrupt monitoring circuit in the host circuit 20 is operating, and the main circuit is stopped. In the normal mode, the entire host circuit 20 operates (i.e., the main circuit also operates). Therefore, the power consumption of the host circuit 20 in the standby mode is smaller than the power consumption of the host circuit 20 in the normal mode.

[0023] The control circuit 21 and the state machine 22 belong to the main circuit. However, the state machine 22 may be operated even in the standby mode. Among the host circuit 20, the main circuit is the interrupt request signal REQ INTIt is activated upon receiving . After the main circuit is activated, the control circuit 21 can read the acceleration read signal RD from the acceleration sensor 10. The acceleration read signal RD read here represents the latest acceleration detection value DET.

[0024] The control circuit 21 has a function of controlling the operation of the transmission circuit 30, and causes the transmission circuit 30 to transmit the radio wave WV at a necessary timing. The state of the transmission circuit 30 is controlled and set to an on state or an off state by the control circuit 21. The on state is an operating state, and the off state is a stop state. In the on state of the transmission circuit 30, the transmission circuit 30 operates, and thus transmits the radio wave WV. In the off state of the transmission circuit 30, the transmission circuit 30 stops. That is, in the off state of the transmission circuit 30, the transmission of the radio wave WV is stopped (the radio wave WV is not transmitted). The radio wave WV is an omnidirectional radio wave, and in the on state of the transmission circuit 30, the radio wave WV is radiated omnidirectionally. A specific example of the operation control of the transmission circuit 30 by the control circuit 21 will be described later.

[0025] The state machine 22 sets the state of the control circuit 21 to state ST1 or ST2. The entity of the state machine 22 is a memory that stores a value indicating which of the states ST1 and ST2 the state of the control circuit 21 is. The value in the memory of the state machine 22 is assumed not to be lost even in the standby mode. The memory of the state machine 22 may be a non-volatile memory. If the state machine 22 operates even in the standby mode, the memory of the state machine 22 may be a volatile memory. The significance of states ST1 and ST2 will become clear from the following description.

[0026] In conjunction with the activation of device 1, the host circuit 20 is activated. When the host circuit 20 is activated, after performing the initial sequence operation in the normal mode, it shifts the operation mode to the standby mode. In the initial sequence operation, the control circuit 21 transmits a setting signal SET for setting the operation conditions of the acceleration sensor 10 and the like to the acceleration sensor 10. The threshold value TH (see FIG. 4) described later is specified by the setting signal SET.

[0027] After the device 1 is activated, a modification in which the host circuit 20 always operates in the normal mode may be applied to the device 1. In this case, each time the acceleration detection value DET is derived at the detection period of the acceleration sensor 10, the acceleration sensor 10 may transmit the latest acceleration detection value DET to the host circuit 20.

[0028] Transmission of the radio wave WV requires relatively large power, and an increase in the transmission time of the radio wave WV accelerates the battery consumption of the device 1. Therefore, while ensuring the transmission of the radio wave WV at the required timing, the transmission time of the radio wave WV should be suppressed as much as possible. A beneficial technology that can suppress unnecessary power consumption as much as possible while not impairing the usage feeling of the user U1 (while satisfying the requirement that the vehicle CR is correctly unlocked when the user U1 approaches the vehicle CR) is adopted in the device 1.

[0029] An internal block diagram of the control circuit 21 for realizing the beneficial technology is shown in FIG. 3, and an operation flowchart of the device 1 is shown in FIG. 4. The control circuit 21 includes a counter 21a, a transmission control unit 21b, and a count reference value setting unit 21c (hereinafter, may be abbreviated as the setting unit 21c). The counter 21a counts and holds the count value CNT. The counter 21a performs an up-count process of increasing the count value CNT by a unit amount each time a fixed time Δt elapses from the initial value, or a down-count process of decreasing the count value CNT by a unit amount each time a fixed time Δt elapses from the initial value, starting from the specified timing. The fixed time Δt is determined depending on the period of the internal clock signal generated within the device 1. Here, the initial value of the count value CNT is zero, and it is assumed that the up-count process is performed by the counter 21a. The state of the transmission circuit 30 is controlled and set to the on state or the off state by the transmission control unit 21b. The setting unit 21c will be described later.

[0030] The operation flow of Device 1 will be described along the operation flowchart of FIG. 4. When Device 1 is activated by attaching a battery to Device 1, it proceeds to Step S11. In Step S11, the control circuit 21 performs the above-described initial sequence operation, and transmits a setting signal SET to the acceleration sensor 10 during the initial sequence operation. The setting signal SET is received by the acceleration sensor 10. In Step S12 following Step S11, the continuous execution of the acceleration detection operation by the acceleration sensor 10 is started. Therefore, after Step S12, the acceleration detection operation for detecting the acceleration acting on Device 1 by the acceleration sensor 10 and deriving an acceleration detection value DET is repeatedly and continuously executed at a predetermined detection period. In Step S13 following Step S12, the state machine 22 sets the state of the control circuit 21 to state ST1. When the state of the control circuit 21 is set to state ST1 in Step S13, the host circuit 20 (or the mode setting circuit) shifts the operation mode of the host circuit 20 to the standby mode.

[0031] Note that the transmission control unit 21b generally maintains the transmission circuit 30 in an off state. When the host circuit 20 is in the standby mode, the transmission circuit 30 is always in the off state. The transmission circuit 30 can be turned on only during a part of the period when the host circuit 20 operates in the normal mode. After Step 13, it proceeds to Step S14.

[0032] In step S14, the acceleration sensor 10 performs an acceleration detection operation to obtain the latest acceleration detection value DET, and the acceleration sensor 10 compares the latest acceleration detection value DET with a predetermined threshold value TH. The threshold value TH is specified by a setting signal SET. In step S15 following step S14, based on the comparison result in step S14, it is confirmed by the acceleration sensor 10 that the latest acceleration detection value DET is greater than the threshold value TH. When the latest acceleration detection value DET is greater than the threshold value TH (Y in step S15), the above-mentioned interrupt condition is satisfied, and the acceleration sensor 10 causes a transition to step S16. When the latest acceleration detection value DET is less than or equal to the threshold value TH (N in step S15), the acceleration sensor 10 causes a transition to step S14 and repeats the processes of steps S14 and S15. However, it may be possible to proceed to step S16 when "DET = TH".

[0033] In step S16, the acceleration sensor 10 transmits an interrupt request signal REQ INT to the host circuit 20, and the interrupt request signal REQ INT is received by the host circuit 20. Triggered by the reception of the interrupt request signal REQ INT , the main circuit of the host circuit 20 is activated, and thus the operation mode of the host circuit 20 transitions from the standby mode to the normal mode. When the main circuit of the host circuit 20 is activated, it proceeds from step S16 to step S17.

[0034] In step S17, the transmission control unit 21b performs a radio wave on process. In the radio wave on process, the transmission control unit 21b sets the transmission circuit 30 to the on state for a predetermined on time t ON , and then returns the transmission circuit 30 to the off state. Therefore, in step S17, the radio wave WV is transmitted from the transmission circuit 30 for only the on time t ON . In FIG. 5, the time T A1 is the transmission start time of the radio wave WV by the radio wave on process in step S17, and the time T A2 is the transmission end time of the radio wave WV by the radio wave on process in step S17. The difference between the times T A1 and T A2 is the on time t ONis equal to.

[0035] Also in step S17, the control circuit 21 performs an acceleration reading process of reading the latest acceleration detection value DET from the acceleration sensor 10. The acceleration detection value DET read in the acceleration reading process of step S17 is particularly referred to as the acceleration detection value DET REF is called. Further in step S17, the setting unit 21c sets a count reference value CNT REF according to the acceleration detection value DET REF by executing a counter setting process.

[0036] In the counter setting process, the setting unit 21c sets the count reference value CNT REF to be larger as the acceleration detection value DET REF is larger. The setting unit 21c may increase the count reference value CNT REF step by step as the acceleration detection value DET REF increases. More specifically, for example, as shown in FIG. 6, the setting unit 21c sets the reference value CNT REF <DET VAL1 ” is established, and sets the reference value CNT REF for the count reference value CNT VAL1 , and sets the reference value CNT VAL1 ≦DET REF <DET VAL2 ” is established, and sets the reference value CNT REF for the count reference value CNT VAL2 , and sets the reference value CNT VAL2 ≦DET REF ” is established, and sets the reference value CNT REF for the count reference value CNT VAL3 . Here, “0 < DET VAL1 <DET VAL2 ” and “0 < CNT VAL1 <CNT VAL2 <CNT VAL3 ” are established. In the example of FIG. 6, the count reference value CNT REF is variably set in three steps according to the acceleration detection value DET REF , but the count reference value CNT REF is set according to the acceleration detection value DET REFIt may be variably set in two steps, or may be variably set in four or more steps.

[0037] The setting unit 21c may continuously increase the count reference value CNT REF as the acceleration detection value DET REF increases. That is, as shown in FIG. 7, the setting unit 21c may set the count reference value CNT REF according to "CNT REF = k × DET REF ". Here, k is a coefficient having a predetermined positive value.

[0038] Also, in step S17, the state transition process is executed by the state machine 22. In the state transition process, the state machine 22 switches the state of the control circuit 21 from state ST1 to state ST2.

[0039] In step S17, the execution order of the radio wave on process, the acceleration reading process, the counter setting process, and the state transition process is arbitrary, and any two or more of these four processes may be executed simultaneously. However, the counter setting process is executed after the acceleration reading process. Referring to FIG. 5 again, the acceleration reading process and the counter setting process may be executed before the time T A1 , may be executed during the period from the time T A1 to the time T A2 , or may be executed after the time T A2 . Similarly, the state transition process may be executed before the time T A1 , may be executed during the period from the time T A1 to the time T A2 , or may be executed after the time T A2 .

[0040] After the execution of the radio wave on process, acceleration reading process, counter setting process, and state switching process in step S17, the process proceeds to step S18. In step S18, the count-up process is started by counter 21a. Before the start of the count-up process, counter 21a is initialized so that the count value CNT has an initial value (here, 0). When the count-up process is started, the count value CNT increases by a unit amount (for example, 1) every time a fixed time Δt elapses from the initial value (here, 0). After step S18, the process proceeds to step S19.

[0041] In step S19, the acceleration detection operation is performed by the acceleration sensor 10 to obtain the latest acceleration detection value DET. The latest acceleration detection value DET obtained in step S19 is read by the control circuit 21, and the control circuit 21 related to step S19 compares the read latest acceleration detection value DET with the threshold value TH. However, the comparison in step S19 may be performed by the acceleration sensor 10. In step S20 following step S19, based on the comparison result in step S19, it is confirmed by the control circuit 21 or the acceleration sensor 10 whether the latest acceleration detection value DET is greater than the threshold value TH. If the latest acceleration detection value DET is greater than the threshold value TH (Y in step S20), the process proceeds to step S21, and if the latest acceleration detection value DET is less than or equal to the threshold value TH (N in step S20), the process proceeds to step S22. However, when "DET = TH", the process may proceed to step S22.

[0042] In step S21, the control circuit 21 determines whether the count value CNT has exceeded the count reference value CNT REF After the count-up process is started in step S18, when the count value CNT exceeds the count reference value CNT REF (that is, when "CNT>CNT REF " is established), the counter 21a outputs an overflow signal indicating that fact. When the overflow signal is output from the counter 21a, the control circuit 21 determines that the count value CNT is the count reference value CNT REFIf it is determined that it has exceeded (Y in step S21), a transition from step S21 to step S13 is caused. When transitioning from step S21 to step S13, the above-described processing from step S13 is executed again. In step S21, if the count value CNT has not exceeded the count reference value CNT REF (N in step S21), the process returns to step S19.

[0043] In step S22, the transmission control unit 21b performs the same radio wave on processing as in step S17. Therefore, in the radio wave on processing according to step S22, the transmission control unit 21b sets the transmission circuit 30 to the on state for a predetermined on time t ON and then returns the transmission circuit 30 to the off state. For this reason, in step S22, the radio wave WV is transmitted from the transmission circuit 30 for only the on time t ON . When the radio wave on processing is completed in step S22, the process returns to step S13. When returning from step S22 to step S13, the above-described processing from step S13 is executed again.

[0044] In addition, the following first modified operation may be performed. In the first modified operation, when it is determined in step S21 that the count value CNT has exceeded the count reference value CNT REF , a transition from step S21 to step S22 is caused, the radio wave on processing in step S22 is performed, and then the process returns to step S13.

[0045] Alternatively, the following second modified operation may be performed. In the second modified operation, when it is determined in step S21 that the count value CNT has exceeded the count reference value CNT REF , a transition from step S21 to step S17 is caused. In step S17 when transitioning from step S21 to step S17, instead of the state switching process, a process of maintaining the state of the control circuit 21 in state ST2 is executed.

[0046] FIG. 8 is a state transition diagram of the device 1. However, in the state transition diagram of FIG. 8, it is assumed that after performing the radio wave on process of step S17, through the acceleration reading process and the counter setting process, the state of the control circuit 21 is switched from state ST1 to state ST2.

[0047] Considering the relationship with the operation flowchart of FIG. 7, the state transition of the device 1 shown in FIG. 8 will be described. First, immediately after the device 1 is started, the control circuit 21 is set to state ST1 (step S13). As long as the acceleration detection value DET is smaller than the threshold value TH, the control circuit 21 is maintained in state ST1 and the transmission circuit 30 is maintained in the off state. After that, when an acceleration detection value DET exceeding the threshold value TH is obtained (Y in step S15), the transmission circuit 30 is turned on for a predetermined on-time t ON is turned on for a certain time and then returned to the off state, and also the acceleration detection value DET REF is used to set the count reference value CNT REF and the state of the control circuit 21 is switched from state ST1 to state ST2 (step S17). After the state of the control circuit 21 is switched to state ST2, the count-up process is started (step S18).

[0048] After the state of the control circuit 21 is switched to state ST2, as long as the acceleration detection value DET exceeds the threshold value TH and the count value CNT does not exceed the count reference value CNT REF , state ST2 is maintained (Y in step 20 and N in step S21). After the state of the control circuit 21 is switched to state ST2, when an acceleration detection value DET smaller than the threshold value TH is obtained (N in step S20), the transmission circuit 30 is turned on for a predetermined on-time t ON is turned on for a certain time and then returned to the off state, and then the control circuit 21 returns to state ST1 (via step S22 to step S13). Also, after the state of the control circuit 21 is switched to state ST2, when "CNT>CNT REF " is established while "DET>TH" is maintained, the control circuit 21 returns to state ST1 (via N in step S21 to step S13).

[0049] FIG. 9 is a state transition diagram of the device 1 when the above-described first modified operation is applied. In the state transition diagram of FIG. 9, after the state of the control circuit 21 is switched to the state ST2, whether an acceleration detection value DET smaller than the threshold value TH is obtained or " REF CNT>CNT ON " is satisfied, the transmission circuit 30 is turned on for a predetermined on-time t

[0050] and then turned off, and thereafter, the control circuit 21 returns to the state ST1. B1 FIG. 10 shows an example of the time-series changes of the acceleration detection value DET, the state of the transmission circuit 30, and the state of the user U1. As time progresses, the times T B2 T B3 T B4 T B5 are visited in this order. The differences between the times T B1 and T B2 , the differences between the times T B2 and T B3 , and the differences between the times T B3 and T B4 are all assumed to be sufficiently longer than the on-time T ON . In FIG. 10, a case where the user U1 moves from a stationary state through a moving state and then returns to the stationary state is assumed.

[0051] Before the time T B1 , the user U1 is stationary, and thus the acceleration detection value DET is sufficiently smaller than the threshold value TH. As a result, before the time T B1 , the state of the control circuit 21 is maintained in the state ST1 and the transmission circuit 30 is maintained in the off state. From the time T B1 to the time T B4 , the user U1 moves toward the vehicle CR. Due to this movement, it is assumed that the acceleration detection values DET sequentially obtained between the times T B1 and T B4 are maintained in a state larger than the threshold value TH.

[0052] The period between the times T B1 and T B4 is the period P1 from the time T B1 to the time T B2 and the time TB2 from time T B3 to period P2, and from time T B3 to time T B4 to period P3. User U1 moves at a relatively low moving speed during periods P1 and P3 (e.g., walks at 4 km / h), and moves at a relatively high moving speed during period P2 (e.g., runs at 10 km / h).

[0053] During periods P1 to P3, after reaching step S21 from step S13, a series of loop processes that return to step S13 based on the establishment of "CNT > CNT REF " are repeatedly executed. In each loop process, a count reference value CNT REF is set based on the acceleration detection value DET obtained in step S17 (i.e., the acceleration detection value DET REF ). Here, it is assumed that the acceleration detection value DET (i.e., the acceleration detection value DET REF ) obtained in step S17 in each loop process during periods P1 and P3 coincides with the value DET L , and the acceleration detection value DET (i.e., the acceleration detection value DET REF ) obtained in step S17 in each loop process during period P2 coincides with the value DET H . Here, "TH < DET L < DET H " holds. Due to the difference in the intensity of the movement of user U1 between periods P1 and P3 and the intensity of the movement of user U1 during period P2, a difference occurs between the acceleration detection value DET (DET L ) during periods P1 and P3 and the acceleration detection value DET (DET H ) during period P2.

[0054] In each loop process during periods P1 and P3, a relatively small first value is set as the count reference value CNT L based on a relatively small acceleration detection value DET (DET REF ). In each loop process during period P2, a relatively large second value is set as the count reference value CNT H based on a relatively large acceleration detection value DET (DET REFis set. The second value is larger than the first value. For example, the first value is the reference value CNT VAL1 and the second value is the reference value CNT VAL3 (see FIG. 6).

[0055] In each loop process in periods P1 to P3, after passing through steps S13 to S16, the transmission circuit 30 is turned on for the on-time t ON only in the radio wave on process of step S17, and then the transmission circuit 30 is maintained in the off state for the waiting time until “CNT>CNT REF ” is satisfied. The waiting time here increases as the count reference value CNT REF increases, and is the off-time t OFF1 in periods P1 and P3, and is the off-time t OFF2 in period P2. That is, in each of periods P1 and P3, after the transmission circuit 30 is turned on for the on-time t ON only, the operation of turning off the transmission circuit 30 for the off-time t OFF1 only is repeated. On the other hand, in period P2, after the transmission circuit 30 is turned on for the on-time t ON only, the operation of turning off the transmission circuit 30 for the off-time t OFF2 only is repeated. Since the count reference value CNT REF in period P2 is larger than the count reference value CNT REF in periods P1 and P3, the off-time t OFF2 is longer than the off-time t OFF1 .

[0056] It can also be considered as follows. The control circuit 21 has a timer. The timer measures the elapsed time (the elapsed time since the transmission circuit 30 was switched from the on state to the off state) using the counter 21a after the radio wave on process of step S17 is completed. After the transition to step S18, when the measurement time by the timer reaches the time corresponding to the count reference value CNT REF (corresponding to the above waiting time) without “DET≦TH” being satisfied (or without “DET<TH” being satisfied), the control circuit 21 causes a transition from step S21 to step S13.

[0057] Time T B4 At the boundary of time T, the state of user U1 changes from the moving state to the stationary state, and at the time immediately after time T B4 User U1 stops in a state where it is sufficiently close to the door DR of the vehicle CR. Therefore, at the time immediately after time T B4 At the time immediately after time T B5 the acceleration detection value DET falls below the threshold value TH and is thereafter maintained at "DET < TH". In the example of FIG. 10, "DET < TH" is satisfied during the execution process of the processes of steps S19 to S21, and as a result, starting from time T B5 the radio wave on process of step S22 is executed. The state of the vehicle CR is switched from the locked state to the unlocked state by the radio wave WV transmitted from the transmission circuit 30 in the radio wave on process of step S22. Note that the distance d during the period P3 is correspondingly small. Therefore, the radio wave WV in the radio wave on process (particularly, for example, the radio wave on process executed immediately before time T B4 ) executed during the period P3 may be received by the receiving circuit of the lock management device 3, and in this case, the state of the vehicle CR is switched from the locked state to the unlocked state during the period P3.

[0058] As understood from the above description, the control circuit 21 intermittently operates the transmission circuit 30 during a period in which the detected acceleration value DET is greater than the threshold value TH, and adjusts the operation interval of the transmission circuit 30 according to the detected acceleration value DET. The radio wave WV is transmitted only when the transmission circuit 30 operates. That is, the control circuit 21 provides an on period in which the radio wave WV is transmitted from the transmission circuit 30 and an off period in which the transmission of the radio wave from the transmission circuit 30 is stopped alternately during a period in which the detected acceleration value DET is greater than the threshold value TH, and adjusts the length of each off period (each off period during a period in which the detected acceleration value DET is greater than the threshold value TH) according to the detected acceleration value DET. Hereinafter, a period in which the detected acceleration value DET is greater than the threshold value TH is referred to as an adjustment target period for convenience. The adjustment target period is, in detail, a period in which the detected acceleration value DET is maintained greater than the threshold value TH (a period in which "DET > TH" is maintained).

[0059] The on-period is the period during which the transmission circuit 30 is in the on-state, and the off-period is the period during which the transmission circuit 30 is in the off-state. In the example of FIG. 10, the length of each off-period during periods P1 and P3 is the off-time t OFF1 and the length of each off-period during period P2 is the off-time t OFF2 . In the example of FIG. 10, the operating interval of the transmission circuit 30 during period P1 or P3 is the sum of the on-time t ON and the off-time t OFF1 (t ON +t OFF1 ), and in one operation of the transmission circuit 30, the radio wave WV is transmitted only for the on-time t ON . In the example of FIG. 10, the operating interval of the transmission circuit 30 during period P2 is the sum of the on-time t ON and the off-time t OFF2 (t ON +t OFF2 ), and in one operation of the transmission circuit 30, the radio wave WV is transmitted only for the on-time t ON . And as described above, “t OFF2 >t OFF1 ”.

[0060] Therefore, the control circuit 21 increases the operating interval of the transmission circuit 30 as the detected acceleration value DET increases in the adjustment target period. That is, the control circuit 21 increases the length of each off-period (each off-period during the adjustment target period) as the detected acceleration value DET increases in the adjustment target period.

[0061] User U1 approaches vehicle CR by moving. Also, the movement of user U1 causes a corresponding acceleration to act on device 1. Therefore, when an acceleration detection value DET exceeding a threshold TH is obtained, radio wave WV should be transmitted, and in response, a radio wave on process is executed in step S17. However, a state where the acceleration acting on device 1 is sufficiently large corresponds to a state where user U1 is moving violently, and it is unlikely that an unlocking state of vehicle CR is required during a period when user U1 is moving violently (for example, a period when user U1 is running in a state where distance d is sufficiently long). Considering this, during an adjustment target period, as the detected acceleration value DET increases, the operating interval of transmission circuit 30 is increased (the length of each off period is increased). Thereby, wasteful power consumption due to unnecessary radio wave transmission can be suppressed.

[0062] As a reference method, a method of always transmitting radio wave WV at a constant interval during a period when "DET>TH" holds (a method of keeping the operating interval of transmission circuit 30 constant) can be considered. In the reference method, if the transmission interval of radio wave WV is set too long, radio wave WV will not be transmitted when radio wave WV is truly needed, and the usability of user U1 will be impaired. In the reference method, if the transmission interval of radio wave WV is set too short, wasteful power consumption will increase. In device 1 according to the present embodiment, since the operating interval of transmission circuit 30 is increased in a situation where it is unlikely that an unlocking state of vehicle CR is required, without impairing the usability of user U1 (while satisfying the requirement that vehicle CR becomes correctly unlocked when user U1 approaches vehicle CR), wasteful power consumption can be suppressed as much as possible.

[0063] Specifically, a state machine 22 that sets the state of control circuit 21 to state ST1 or ST2 is used. When an acceleration detection value DET greater than threshold TH is obtained by acceleration sensor 10 in state ST1 (when transitioning from the state of "DET<TH" to the state of "DET>TH"; Y in step S15), control circuit 21 turns on transmission circuit 30 for on-time t ONOnly transmit the radio wave WV, and the state machine 22 switches the state of the control circuit 21 from state ST1 to state ST2 (step S17). After the state of the control circuit 21 is switched to state ST2, if "DET < TH" holds before the elapse of the specified time, the control circuit 21 transmits the radio wave WV for only the on-time t from the transmission circuit 30 ON Only transmit the radio wave WV (step S22), and the state machine 22 returns the state of the control circuit 21 to state ST1 (step S13).

[0064] As a result, when the user U1 stops in front of the vehicle CR after moving or when the intensity of the user U1's movement decreases, the radio wave WV is transmitted (step S22), and the vehicle CR switches from the locked state to the unlocked state as desired by the user U1. The above specified time is the time from the start of the count-up process in step S18 until "CNT < CNT REF " holds, and is determined by the count reference value CNT REF (the specified time increases as the count reference value CNT REF increases, and the specified time decreases as the count reference value CNT REF decreases). The above specified time corresponds to the off-time t OFF1 in periods P1 and P3, and corresponds to the off-time t OFF2 in period P2.

[0065] Also, after the state machine 22 switches the state of the control circuit 21 to state ST2 (step S17), when the specified time elapses while "DET > TH" is maintained (Y in step S21), the state of the control circuit 21 is returned to state ST1 (step S13). When the acceleration detection value DET after the state of the control circuit 21 is returned to state ST1 is greater than the threshold value TH (Y in step S15), the control circuit 21 transmits the radio wave WV for only the on-time t from the transmission circuit 30 again, and the state machine 22 switches the state of the control circuit 21 from state ST1 to state ST2 again (step S17). ON Only transmit the radio wave WV, and the state machine 22 switches the state of the control circuit 21 from state ST1 to state ST2 again (step S17).

[0066] The control circuit 21 detects the acceleration value DET when its own state is switched from state ST1 to state ST2REF As it increases, the specified time is increased, and thus, when the state of the object itself is switched from state ST1 to state ST2, the detected acceleration value DET REF is decreased as it decreases. By increasing and decreasing the specified time in this manner, the control circuit 21 adjusts the operating interval of the transmission circuit 30 during the adjustment target period (adjusts the length of each off period).

[0067] Referring to FIG. 1, the vehicle CR (or door DR) is given as an example of the object, but the object is not limited thereto. For example, the object may be a house (or the door of a house), or any facility (or the door of a facility). An electronic device such as a smartphone or a personal computer may also be the object.

[0068] The acceleration sensor 10 may be a two-axis acceleration sensor that detects the respective accelerations in the X-axis and Y-axis directions. The two-axis acceleration sensor does not have a function of detecting the acceleration in the Z-axis direction. When the acceleration sensor 10 is a two-axis acceleration sensor, the acceleration vector will have only X-axis and Y-axis components. In particular, for example, when the relationship between the X-axis and Y-axis directions and the direction in which gravity acts (the direction of gravitational acceleration) is determined to a certain extent, the acceleration sensor 10 can be a two-axis acceleration sensor. Alternatively, the acceleration sensor 10 may be a uniaxial acceleration sensor that detects only the acceleration in one axial direction. When the acceleration sensor 10 is a uniaxial acceleration sensor, the acceleration detection value DET is the magnitude of the acceleration in the uniaxial direction detected by the acceleration sensor 10. In particular, for example, when the relationship between the uniaxial direction and the direction in which gravity acts (the direction of gravitational acceleration) is determined to a certain extent, the acceleration sensor 10 can be a uniaxial acceleration sensor.

[0069] Embodiments of the present disclosure can be appropriately modified in various ways within the scope of the technical idea shown in the claims. The above embodiments are merely examples of the embodiments of the present disclosure, and the meanings of the terms of the present disclosure or each constituent element are not limited to those described in the above embodiments. The specific numerical values shown in the above description are merely examples, and of course, they can be changed to various numerical values.

[0070] <<Supplementary Note>> A supplementary note is provided for the present disclosure in which specific configuration examples are shown in the above embodiments.

[0071] A wireless transmitter (2) according to one aspect of the present disclosure includes an acceleration sensor (10) configured to sequentially detect an acceleration acting on itself and sequentially derive an acceleration detection value (DET), a transmission circuit (30) configured to be able to transmit radio waves (WV), and a control circuit (21) configured to control the operation of the transmitter based on the acceleration detection value. The control circuit provides, in a target period (adjustment target period) in which the acceleration detection value is greater than a threshold value (TH), an on period in which the radio wave is transmitted from the transmission circuit and an off period in which the transmission of the radio wave from the transmission circuit is stopped alternately, and adjusts the length of each off period according to the detected acceleration value (first configuration).

[0072] Thereby, the length of the off period can be appropriately adjusted according to the state (motion state) of the user who holds the wireless transmitter, and it is possible to suppress unnecessary radio wave transmission as much as possible while ensuring radio wave transmission at a necessary timing through the adjustment.

[0073] In the wireless transmitter according to the first configuration, the control circuit may be configured to increase the length of each off period as the acceleration detection value increases in the target period (second configuration).

[0074] In the wireless transmitter according to the second configuration, a state machine (22) is provided that is configured to set the state of the control circuit to a first state (ST1) or a second state (ST2). When the acceleration detection value greater than the threshold value is obtained by the acceleration sensor in the first state (Y in S15), the control circuit causes the transmission circuit to transmit the radio wave for a predetermined on-time (t ON ) and the state machine switches the state of the control circuit from the first state to the second state (S17). After the state of the control circuit is switched to the second state, if the acceleration detection value becomes smaller than the threshold value before the elapse of a specified time (N in S20), the control circuit may cause the transmission circuit to transmit the radio wave for the on-time and the state machine may return the state of the control circuit to the first state (third configuration).

[0075] In the wireless transmitter according to the third configuration, after the state machine switches the state of the control circuit to the second state (S17), when the specified time elapses while the acceleration detection value remains greater than the threshold value (Y in S21), the state machine returns the state of the control circuit to the first state. When the acceleration detection value after the state of the control circuit is returned to the first state is greater than the threshold value, the control circuit may cause the transmission circuit to transmit the radio wave for the on-time again and the state machine may switch the state of the control circuit from the first state to the second state again (S17 again) (fourth configuration).

[0076] In the wireless transmitter according to the fourth configuration, the control circuit may increase the specified time as the acceleration detection value (DET REF ) increases when the state of the control circuit is switched from the first state to the second state, thereby adjusting the length of each off-period in the target period (fifth configuration).

[0077] In the wireless transmitter according to any one of the first to fifth configurations, the radio wave may have a configuration (sixth configuration) including a signal (unlocking signal) for shifting an object (CR) from a locked state to an unlocked state.

Explanation of Signs

[0078] U1 User CR Vehicle DR Door d Distance WV Radio wave 1 Remote access device 2 Wireless transmitter 3 Lock management device 10 Acceleration sensor 20 Host circuit 21 Control circuit 21a Counter 21b Transmission control unit 21c Count reference value setting unit 22 State machine 30 Transmission circuit REQ INT Interrupt request signal RD Acceleration read signal SET Setting signal

Claims

1. An acceleration sensor configured to sequentially detect the acceleration acting on itself and sequentially derive an acceleration detection value, A transmission circuit configured to be able to transmit radio waves, A control circuit configured to control the operation of the transmitter based on the acceleration detection value, comprising: The control circuit provides an on period in which the radio wave is transmitted from the transmission circuit and an off period in which the transmission of the radio wave from the transmission circuit is stopped alternately in a target period in which the acceleration detection value is greater than a threshold value, and adjusts the length of each off period according to the detected acceleration value , A wireless transmitter.

2. The control circuit increases the length of each off period as the acceleration detection value increases in the target period , The wireless transmitter according to claim 1.

3. A state machine configured to set the state of the control circuit to a first state or a second state is provided, When an acceleration detection value greater than the threshold value is obtained by the acceleration sensor in the first state, the control circuit causes the transmission circuit to transmit the radio wave for a predetermined on time and the state machine switches the state of the control circuit from the first state to the second state, After the state of the control circuit is switched to the second state, if the acceleration detection value becomes smaller than the threshold value before a specified time elapses, the control circuit causes the transmission circuit to transmit the radio wave for the on time and the state machine returns the state of the control circuit to the first state , The wireless transmitter according to claim 2.

4. The state machine returns the state of the control circuit to the first state when the specified time elapses while the acceleration detection value remains greater than the threshold value after the state of the control circuit is switched to the second state, When the acceleration detection value after the state of the control circuit is returned to the first state is greater than the threshold value, the control circuit causes the transmission circuit to transmit the radio wave for the on time again and the state machine switches the state of the control circuit from the first state to the second state again , The wireless transmitter according to claim 3.

5. The control circuit increases the specified time as the acceleration detection value increases when the state of the control circuit is switched from the first state to the second state, thereby adjusting the length of each off period in the target period , The wireless transmitter according to claim 4.

6. The radio wave includes a signal for shifting an object from a locked state to an unlocked state. The wireless transmitter according to any one of claims 1 to 5.

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