JP2016025807A - Non-contact power transmission device and input system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission device capable of appropriately stopping power transmission from a power transmission unit when a battery in a power reception unit is fully charged.SOLUTION: A non-contact power transmission device 100 comprises: a power transmission unit 10 including a power transmission coil 16 for generating a magnetic flux by using a power supply; a power reception unit 20 including a power reception coil 21 to which power transmission is performed using electromagnetic induction by the power transmission coil 16 to charge a capacitor 23; a light emitting unit 24 that is provided in the power reception unit 20, monitors a charge state of the capacitor 23, and issues a notification when the capacitor 23 has been fully charged; and a light receiving unit 17 that is provided in the power transmission unit 10 and stops the power transmission on the basis of the notification from the light emitting unit 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a contactless power transmission device and an input system including the same.

  When a thin pen (stylus) is used on the capacitive touch panel, the contact area is small and it is difficult to detect the contact position. In Patent Document 1, an input using a stylus with a small contact area is made possible by increasing a contact position detection signal flowing through a capacitor when the tip of the stylus is brought into contact with a capacitive touch panel. An input device is disclosed.

  The stylus described in Patent Document 1 requires a power source such as a battery. Examples of the battery include a super capacitor (super CAP), a lithium ion capacitor (Li-ion CAP), a nickel metal hydride (Ni-MH) battery, and a lithium ion (Li-ion) battery.

  Cited Document 2 discloses a method for charging a battery of a coordinate pointing pen in a contactless manner. Patent Document 3 discloses a method for charging a battery of a position indicator in a non-contact manner by an induced current flowing in a coil of a resonance circuit provided in the position indicator.

JP 2007-183809 A JP-A-3-139713 JP 2007-164356 A

  Generally, the current consumption of the power transmission unit is large at the start of charging of the battery of the power receiving unit, and the current consumption decreases as the battery approaches full charge. Usually, when the current consumption of the power transmission unit reaches a current value at which it is determined that the battery is fully charged, the transmission of power from the power transmission unit is stopped.

  However, when the power transmission unit is a tablet or the like, the transmission power is relatively small, and the transmission power may be almost constant at the start of charging and at the time of full charging. As described above, when charging is performed in a state where the transmission power is substantially constant, there is a problem that it is not possible to determine whether or not the battery of the power receiving unit is fully charged based on the current consumption of the power transmitting unit.

  The present invention has been made against the background of such problems, and an object of the present invention is to provide a contactless power transmission device capable of appropriately stopping power transmission from the power transmission unit when the battery of the power reception unit is fully charged. And an input system using the same.

  A non-contact power transmission device according to the present invention includes a power transmission unit having a power transmission coil that generates magnetic flux from a power source, a power reception unit having a power reception coil that performs power transmission by electromagnetic induction by the power transmission coil and charges a battery, and the power reception Based on the notification from the charge monitoring unit, and a charge monitoring unit that monitors the charge state of the battery and issues a notification when the battery is fully charged. And a power transmission control unit for stopping power transmission.

  According to the present invention, it is possible to provide a non-contact power transmission device that can appropriately stop power transmission from the power transmission unit when the battery of the power reception unit is fully charged.

It is a figure which shows an example of the non-contact electric power transmission apparatus concerning embodiment. It is a figure which shows the example which provided the light emission part of the non-contact electric power transmission apparatus concerning embodiment in the stylus. It is a figure which shows the example which provided the light-receiving part of the non-contact electric power transmission apparatus concerning embodiment in the tablet. It is a figure explaining an example of operation | movement of the non-contact electric power transmission apparatus concerning embodiment. It is a figure explaining the other example of operation | movement of the non-contact electric power transmission apparatus concerning embodiment.

Embodiment A configuration of a non-contact power transmission apparatus according to an embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a configuration of a non-contact power transmission apparatus 100 according to the embodiment. As shown in FIG. 1, the non-contact power transmission apparatus 100 includes a power transmission unit 10 and a power reception unit 20. The power transmission unit 10 includes a power source 11, a power reception unit detection unit 12, an oscillation circuit 13, a coil 14, a matching circuit 15, a power transmission coil 16, and a light reception unit 17. The oscillation circuit 13 includes a pulse signal source 18 and a MOSFET 19. In the example shown in FIG. 1, an n-type MOSFET 19 is used as a switching element. The power receiving unit 20 includes a power receiving coil 21, a rectifier circuit 22, a capacitor 23, and a light emitting unit 24.

  The non-contact power transmission apparatus 100 transmits power using electromagnetic induction. In the non-contact power transmission apparatus 100, the power transmission coil 16 and the power reception coil 21 are arranged close to each other, and a magnetic flux generated by passing a current through the power transmission coil 16 is used for the power reception coil 21. Electric power is transmitted by generating an electromotive force.

  Hereinafter, each configuration will be described in detail. The power source 11 is connected to the oscillation circuit 13 via the power reception unit detection unit 12. The power source 11 is connected to one end of the coil 14 via the power receiving unit detection unit 12. The other end of the coil 14 is connected to the drain of the MOSFET 19 of the oscillation circuit 13. The source of the MOSFET 19 is grounded. A pulse signal source 18 is connected to the gate of the MOSFET 19.

  The power supply 11 supplies DC power to the oscillation circuit 13 via the power reception unit detection unit 12. Further, DC power from the power source 11 is supplied to one end of the coil 14 via the power receiving unit detection unit 12. When DC power is supplied from the power supply 11, the pulse signal source 18 generates a pulse waveform signal at a constant frequency. The pulse waveform signal is input to the gate of the MOSFET 19. AC power is generated by switching the MOSFET 19 according to the frequency of the pulse waveform signal.

  The generated AC power is input to the matching circuit 14. The matching circuit 14 performs impedance matching and outputs transmission power to the power transmission coil 16. The power transmission coil 16 transmits the transmission power from the matching circuit 14 to the power reception coil 21 on the power reception unit side.

  The power receiving coil 21 is connected to the rectifier circuit 22. The rectifier circuit 22 is connected to the capacitor 23. In the example shown in FIG. 1, a capacitor 23 is used as a rechargeable battery. Various rechargeable batteries such as a super capacitor (super CAP), a lithium ion capacitor (Li-ion CAP), a nickel metal hydride (Ni-MH) battery, a lithium ion (Li-ion) battery, etc. Types can be used.

  The power receiving coil 21 receives the transmission power from the power transmission coil 16 and outputs it to the rectifier circuit 22. The rectifier circuit 22 converts the input transmission power into DC power. The capacitor 23 is charged with DC power.

  In the present embodiment, in the power receiving unit 20, the light emitting unit 24 is connected in parallel with the capacitor 23. In the power transmission unit 10, a light receiving unit 17 is connected to the oscillation circuit 13. The light emitting unit 24 is a charge monitoring unit that monitors the charged state of the capacitor 23. The light emitting unit 24 issues a notification when the capacitor 23 is fully charged. In the present embodiment, the light emitting unit 24 emits light when the capacitor 23 reaches a voltage value determined to be fully charged. As the light emitting unit 24, for example, a light emitting element such as an LED (Light-emitting Diode) can be used. As the light emitting unit 24, a display element such as an LCD (Liquid Crystal Display) can be used. When a display element is used as the light emitting unit 24, the battery remaining amount can be displayed on the display element. In order to suppress power consumption, the display element may intermittently display the remaining battery level, or may temporarily display for warning only when the remaining battery level falls below a predetermined value. it can.

  When the light emitted from the light emitting unit 24 is received by the light receiving unit 17, the generation of AC power in the oscillation circuit 13 is stopped. That is, the light receiving unit 17 configures a power transmission control unit that stops power transmission based on the notification from the light emitting unit 24. Thus, in the present embodiment, the light emitting unit 24 monitors whether or not the capacitor 23 is fully charged, and the light receiving unit 17 performs an operation of stopping power transmission when the capacitor 23 is fully charged.

  Thereby, even if the power transmission unit is a tablet or the like and the transmission power is relatively small, and the transmission power is almost constant between the start of charging of the capacitor 23 and the full charge, the power transmission unit 10 is fully charged when the capacitor 23 is fully charged. Power transmission from can be stopped appropriately.

  The power transmission unit 10 is provided with a power reception unit detection unit 12. The power reception unit detection unit 12 detects whether or not the power reception unit 20 is coupled to the power transmission unit 10 in a chargeable state. When the power receiving unit detecting unit 12 detects that the power receiving unit 20 is coupled to the power transmitting unit 10 and the capacitor 23 is not fully charged, power transmission from the power transmitting unit 10 is started. This will be described in detail later.

  The non-contact power transmission apparatus 100 according to the present embodiment is suitably used for an input system having a position indicator that requires charging and a position detector that detects a position indicated by the position indicator. Examples of the position indicator include an electronic pen and a stylus. Examples of the position detector include a coordinate input device and a stylus input device.

  Here, an example in which the non-contact power transmission device 100 is applied to the tablet 40 including the electronic pen 30 will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram illustrating an example in which the light emitting unit 24 is provided in the electronic pen 30. FIG. 3 is a diagram illustrating an example in which the light receiving unit 17 is provided in the tablet 40.

  The electronic pen 30 is provided with the power receiving unit 20 described above. The tablet 40 is provided with the above-described power transmission unit 10. As shown in FIG. 3, the tablet 40 is provided with an insertion hole 41 into which the electronic pen 30 can be inserted. The insertion hole 41 is formed in a size that can accommodate the electronic pen 30.

  Although not shown here, the power transmission coil 16 is provided in the insertion hole 41. The power transmission coil 16 is wound around an area in which the electronic pen 30 is accommodated. When the electronic pen 30 is inserted into the insertion hole 41, the power reception unit 20 is coupled to the power transmission unit 10 in a state where the power reception unit 20 can be charged. That is, when the electronic pen 30 is inserted into the insertion hole 41, the capacitor 23 can receive power with the transmission power from the power transmission coil 16.

  Next, the operation of the non-contact power transmission apparatus 100 will be described with reference to FIG. FIG. 4 is a diagram for explaining an example of the operation of the non-contact power transmission apparatus 100 according to the embodiment. In FIG. 4, the voltage of the capacitor 23 is shown as a CAP voltage. Further, it is assumed that the electronic pen 30 is inserted into the insertion hole 41 at the timing indicated by the arrow.

  As shown in FIG. 4A, before the electronic pen 30 is inserted, the oscillation circuit 13 provided in the power transmission unit 10 on the tablet 40 side performs intermittent oscillation. At this time, the power reception unit detection unit 12 detects whether or not the electronic pen 30 is inserted. As a method of detecting whether or not the electronic pen 30 is inserted, for example, a method of detecting based on a difference in current consumption on the power transmission unit 10 side can be employed.

  When the electronic pen 30 is inserted into the insertion hole 41, the power transmission coil 16 and the power reception coil 21 are electromagnetically coupled, so that the current flowing through the power transmission coil 16 increases. That is, the current consumption when the electronic pen 30 is inserted into the insertion hole 41 is larger than the current consumption when the electronic pen 30 is not inserted.

  As illustrated in FIG. 4B, when the electronic pen 30 is inserted, the power receiving unit detection unit 12 detects the insertion of the electronic pen 30 during intermittent oscillation after the insertion of the electronic pen 30. In response to this, power transmission from the power transmission unit 10 is started (power transmission ON). The oscillation circuit 13 is controlled to a continuous oscillation operation, and power transmission to the power receiving unit 20 is continued. Thereby, the capacitor 23 is charged and the CAP voltage rises.

  Thereafter, when the voltage value (first threshold value) at which the CAP voltage is determined to be fully charged in FIG. 4 (3), the light emitting unit 24 emits light and the power transmitting unit 10 side is notified that it is fully charged. When receiving the light from the light emitting unit 24, the light receiving unit 17 controls the oscillation circuit 13 to stop power transmission (power transmission OFF). Thereby, when charging is unnecessary, power transmission can be stopped appropriately, and wasteful power consumption can be suppressed. Thereafter, the oscillation circuit 13 is controlled to an intermittent oscillation operation.

  Then, as shown in FIG. 4 (4), when the CAP voltage decreases and becomes equal to or lower than a second threshold value lower than the first threshold value, the light emitting unit 24 is turned off. That is, the CAP voltage when the light emitting unit 24 transitions from non-light emission to light emission is different from the CAP voltage when transition from light emission to non-light emission.

  The light emitting unit 24 emits light when it detects that the capacitor 23 is fully charged, but consumes power at this time. As a result, the voltage of the capacitor 23 is lowered, and another problem that it is difficult for the light emitting unit 24 to hold the fully charged display of the capacitor 23 occurs. In the embodiment, the CAP voltage when the light emitting unit 24 transitions from lighting to off is lower than the CAP voltage when the light emitting unit 24 transitions from lighting to lighting. Thereby, it becomes possible for the light emission part 24 to hold | maintain the display of a full charge.

  In FIG. 4 (4), it is assumed that the state in which the electronic pen 30 is inserted into the insertion hole 41 is maintained. When the light emitting unit 24 is turned off and the power receiving unit detection unit 12 detects insertion of the electronic pen 30 during intermittent oscillation, the power transmission unit 10 starts power transmission again (power transmission ON).

  If the power transmission unit 10 stops power transmission in accordance with the full charge notification from the power reception unit 20, the charge stored in the capacitor 23 by the light emitting unit 24, the circuit inside the electronic pen 30 or the like is consumed and used by the user. There is a possibility that the power charged in the capacitor 23 has been discharged when desired.

  In the embodiment, when it is detected that the electronic pen 30 is inserted and the capacitor 23 is not fully charged, power transmission from the power transmission unit 10 is repeatedly performed. As described above, when the electronic pen 30 is inserted, if the capacitor 23 needs to be charged, power transmission is started as appropriate, and the fully charged state of the capacitor 23 can be maintained.

  Next, another operation of the non-contact power transmission apparatus 100 will be described with reference to FIG. FIG. 5 is a diagram for explaining another example of the operation of the non-contact power transmission apparatus 100 according to the embodiment. In FIG. 5, the voltage of the capacitor 23 is shown as a CAP voltage. Further, it is assumed that the electronic pen 30 is inserted into the insertion hole 41 at the timing indicated by the arrow.

  In the example of FIG. 5, insertion of the electronic pen 30 is detected by a mechanical switch (not shown). As illustrated in FIG. 5A, when the mechanical switch is turned on, the power receiving unit detection unit 12 detects the insertion of the electronic pen 30. When insertion of the electronic pen 30 is detected, the power transmission unit 10 starts power transmission (power transmission ON). Thereby, the capacitor 23 is charged and the CAP voltage rises. The mechanical switch may be built in the power transmission unit 10 or provided outside the power transmission unit 10.

  Thereafter, when the CAP voltage reaches a voltage value (first threshold value) determined to be fully charged in FIG. 5B, the light emitting unit 24 emits light. When the light receiving unit 17 receives light from the light emitting unit 24, the power transmission unit 10 stops power transmission (power transmission OFF). Thereby, when charging is unnecessary, power transmission can be stopped appropriately, and wasteful power consumption can be suppressed.

  As shown in FIG. 5 (3), when the CAP voltage decreases and becomes equal to or lower than a second threshold value lower than the first threshold value and the light emitting unit 24 is turned off, the power transmitting unit 10 starts power transmission again (power transmission ON). Thus, when the mechanical switch is on and the capacitor 23 is not fully charged, power transmission from the power transmission unit 10 is repeatedly performed. As shown in FIG. 5 (4), when the electronic pen 30 is removed from the insertion hole 41, the mechanical switch is turned off. In this case, power transmission from the power transmission unit 10 is stopped.

  The detection of insertion of the electronic pen 30 into the insertion hole 41 is not limited to the above example. For example, it is also possible to detect the insertion of an electronic pen by intermittently oscillating to generate magnetism in the tablet-side transformer and magnetically coupling with the pen-side transformer. Further, it is possible to adopt a method for detecting an electronic pen by detecting a change in impedance due to magnetic coupling between a transformer on the electronic pen side and a transformer on the tablet side.

  The light receiving unit 17 of the power transmission unit 10 may erroneously recognize the full charge of the capacitor 23 due to the influence of ambient light. Therefore, as shown in FIG. 2, the light emitting unit 24 is provided not near the tip of the electronic pen 30 but near the center in the longitudinal direction of the shaft of the electronic pen 30. As shown in FIG. 3, the light receiving portion 17 is provided in the insertion hole 41.

  When the electronic pen 30 is housed in the insertion hole 41, the light emitting unit 24 and the light receiving unit 17 are arranged at a position that cannot be seen from the outside. As a result, the influence of ambient light can be suppressed, and erroneous recognition of the fully charged state of the capacitor 23 can be prevented.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the configuration of the above embodiment, and those skilled in the art within the scope of the invention of the claims of the present application claims. It goes without saying that various modifications, modifications, and combinations that can be made are included.

DESCRIPTION OF SYMBOLS 100 Contactless power transmission apparatus 10 Power transmission part 11 Power supply 12 Power receiving part detection part 13 Oscillation circuit 14 Coil 15 Matching circuit 16 Power transmission coil 17 Light receiving part 18 Pulse signal source 19 MOSFET
20 power receiving unit 21 power receiving coil 22 rectifier circuit 23 capacitor 24 light emitting unit 30 electronic pen 40 tablet 41 insertion hole

Claims (10)

A power transmission unit having a power transmission coil for generating magnetic flux by a power source;
A power receiving unit having a power receiving coil for performing power transmission by electromagnetic induction by the power transmission coil and charging a battery;
A charge monitoring unit that is provided in the power receiving unit, monitors a charging state of the battery, and issues a notification when the battery is fully charged;
A power transmission control unit that is provided in the power transmission unit and stops power transmission based on the notification from the charge monitoring unit;
Comprising
Non-contact power transmission device. The charge monitoring unit has a light emitting unit that emits light when the battery is fully charged,
The power transmission control unit includes a light receiving unit that receives light from the light emitting unit,
The contactless power transmission device according to claim 1. The battery voltage when the light emitting unit transitions from non-light emission to light emission is different from the battery voltage when transition from light emission to non-light emission,
The non-contact power transmission device according to claim 2. The power transmission unit further includes a power reception unit detection unit that detects whether or not the power reception unit is coupled to the power transmission unit in a chargeable state,
When the power receiving unit detection unit detects the coupling of the power receiving unit and the battery is not fully charged, power transmission from the power transmitting unit is started.
The non-contact electric power transmission apparatus of any one of Claims 1-3. A position indicator;
A position detector for detecting a position indicated by the position indicator;
A power transmission unit provided in the position detector and having a power transmission coil that generates magnetic flux by a power source;
A power receiving unit that is provided in the position indicator, performs power transmission by electromagnetic induction by the power transmission coil, and has a power receiving coil that charges a battery of the position indicator;
A charge monitoring unit that is provided in the power receiving unit, monitors a charging state of the battery, and issues a notification when the battery is fully charged;
A power transmission control unit that is provided in the power transmission unit and stops power transmission based on the notification from the charge monitoring unit;
Comprising
Input system. The charge monitoring unit has a light emitting unit that emits light when the battery is fully charged,
The power transmission control unit includes a light receiving unit that receives light from the light emitting unit,
The input system according to claim 5. The battery voltage when the light emitting unit transitions from non-light emission to light emission is different from the battery voltage when transition from light emission to non-light emission,
The input system according to claim 6. The power transmission unit further includes a power reception unit detection unit that detects whether or not the power reception unit is coupled to the power transmission unit in a chargeable state,
When the power receiving unit detection unit detects the coupling of the power receiving unit and the battery is not fully charged, power transmission from the power transmitting unit is started.
The input system according to claim 6 or 7. The position detector further comprises an insertion hole into which the position indicator can be inserted,
When the power transmission coil is provided in the insertion hole and the position indicator is inserted into the insertion hole, the power reception unit is coupled to the power transmission unit in a chargeable state,
The input system according to claim 8, wherein the light receiving unit is provided in the insertion hole. The power transmission unit further includes a power reception unit detection unit that detects whether or not the power reception unit is coupled to the power transmission unit in a chargeable state,
When the power receiving unit detection unit detects the coupling of the power receiving unit and the battery is not fully charged, power transmission from the power transmitting unit is started.
The input system according to claim 5.

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