Power source circuit

Abstract

To eliminate an unstable state when a power supply is switched.SOLUTION: A power supply circuit includes: a power supply switching unit that selectively outputs a power supply voltage from an internal battery and a power supply voltage from an AC adapter; a DC / DC converter that receives the power supply voltage from the power supply switching unit and outputs a power supply voltage of a predetermined voltage value to a power supply voltage line for a load; and a switching delay circuit that controls the power supply switching unit such that the power supply voltage from the internal battery is output during a period in which the power supply voltage input from the AC adapter is not detected and such that the power supply voltage from the AC adapter is output after a predetermined delay time elapses when the power supply voltage input from the AC adapter is detected.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a power supply circuit that can accommodate both a built-in battery and an AC adapter. [Background technology]

[0002] A power supply circuit is commonly used that supplies a power supply voltage from an internal battery to a load, and also supplies a power supply voltage from an external power supply to the load when an AC adapter is connected.

[0003] The following Patent Document 1 discloses that the device has a switch circuit that switches between a battery and an external power source, and that the on / off switching is controlled by a control signal from a connector protection circuit. It also discloses a delay circuit to prevent chattering in connector connection detection. The following Patent Document 2 describes how to handle a power outage from an adapter. That is, in order to output direct current of a rated voltage from a secondary battery to an output connector, a power outage detection circuit detects a power outage and outputs a power outage signal to a control circuit, and the control circuit switches an output switch from an OFF state to an ON state in response to the power outage signal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-176581 A [Patent Document 2] JP 2017-188967 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in devices that can use both an external power source via an AC adapter and an internal battery power source, when switching between the two power sources, the power supply voltage can become unstable or a momentary interruption can occur. This is particularly problematic for devices with large load power consumption.

[0006] Therefore, the present invention proposes a configuration for preventing the power supply voltage from becoming unstable when switching power sources in a power supply circuit in a device that selectively uses a power supply voltage from an internal battery and a power supply voltage input from an AC adapter. [Means for solving the problem]

[0007] The power supply circuit of the present invention comprises a power supply switching unit which selectively outputs a power supply voltage from an internal battery and a power supply voltage from an AC adapter, a DC / DC converter which receives the power supply voltage from the power supply switching unit and outputs a power supply voltage of a predetermined voltage value to a power supply voltage line for a load, and a switching delay circuit which controls the power supply switching unit so that the power supply voltage from the internal battery is output during a period when power supply voltage input from the AC adapter is not detected, and when power supply voltage input from the AC adapter is detected, the power supply voltage from the AC adapter is output after a predetermined delay time has elapsed. When an AC adapter is connected and a power supply voltage is detected from the outside, a power supply switching unit does not immediately switch the power supply voltage, but outputs the power supply voltage from the AC adapter after a predetermined time has elapsed.

[0008] Furthermore, the power supply circuit of the present invention includes a complement circuit that can turn on / off the application of the power supply voltage from the internal battery to the power supply voltage line, and a complement control unit that turns on the complement circuit while the power supply voltage input from the AC adapter is detected, and controls the complement circuit to be turned off after a predetermined time has elapsed when the power supply voltage input from the AC adapter is no longer detected. When the power supply voltage from the AC adapter is lost, the supplementary circuit is turned on so that the power supply voltage from the internal battery is applied to the power supply voltage line. Effect of the Invention

[0009] According to the power supply circuit of the present invention, when power supply from an AC adapter begins, the power supply voltage is switched only after the power supply voltage output from the AC adapter has stabilized, thereby avoiding unstable operation when switching to the AC adapter. In addition, when the power supply from the AC adapter is terminated, such as when the AC adapter is removed, the power supply voltage from the internal battery is supplemented, preventing momentary power outages caused by voltage drops. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram of a communication system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of each component constituting the communication system according to the embodiment. [Diagram 3] FIG. 1 is a block diagram of a power supply circuit of a comparative example. [Figure 4] FIG. 13 is an explanatory diagram of switching to power supply from an AC adapter in a comparative example. [Diagram 5] FIG. 11 is an explanatory diagram of a comparative example when switching to battery power supply. [Figure 6] 1 is a block diagram of a power supply circuit according to an embodiment; [Figure 7] FIG. 11 is an explanatory diagram of switching to power supply from an AC adapter according to an embodiment. [Figure 8] FIG. 11 is an explanatory diagram of switching to battery power supply according to an embodiment. [Figure 9] 5 is a flowchart of control when switching to battery power supply in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described. In the embodiment, an example of a power supply circuit mounted on a control device for an unmanned vehicle will be given.

[0012] <1. System Overview> Figure 1 shows a drone 2 as an example of an unmanned mobile body, and a control device 1 for the drone 2. The communication system between the control device 1 and the drone 2 is a high-speed wireless transmission system capable of long-distance communication up to approximately 5 km.

[0013] A control signal is transmitted from the control device 1 to the drone 2 to control the flight of the drone 2 and the shooting operation of the camera 82 mounted on the drone 2. Image signals captured by the camera 82 and telemetry data from the drone 2 are transmitted from the drone 2 to the control device 1.

[0014] In this case, the first wireless communication and the second wireless communication are performed simultaneously in parallel between the control device 1 and the drone 2. In the first wireless communication, an image signal is transmitted from the drone 2 to the control device 1 via one-way communication using a first frequency band, for example the 5.7 GHz band. In the second wireless communication, control signals and telemetry data request signals are transmitted from the control device 1 to the drone 2, and telemetry data is transmitted from the drone 2 to the control device 1, using simplex communication in a second frequency band, for example the sub-GHz band.

[0015] The sub-GHz band of the second wireless communication is, for example, 920 MHz. The telemetry data is information obtained by various sensors on the drone side, such as altitude information, location information by the Global Navigation Satellite System (GNSS), temperature information, air pressure information, attitude information of the drone 2, remaining battery information, and the like. Control signals sent from the control device 1 via the second wireless communication include control signals (control signals) for flight control of the drone 2, and control signals (camera operation signals) related to the shooting operation of the camera 82 mounted on the drone 2.

[0016] The image signal transmitted by the first wireless communication is, for example, a Full HD (Full High Definition) image, allowing high-quality images (video or still images) captured by the camera 82 of the drone 2 to be viewed on the control device 1 side.

[0017] The control device 1, which will be described in detail later, is used by attaching a separate information processing device, a tablet PC 3. The display screen 30 of the tablet PC 3 can be used to display images based on received image signals and information based on telemetry data.

[0018] Furthermore, the control device 1 can be connected to, for example, an external monitor device 4, and can be supplied with and display an image signal received via the first wireless communication. In addition, a memory card 5, for example, can be attached to the control device 1 as a storage medium, and image signals received via the first wireless communication can be stored in the memory card 5.

[0019] The control device 1 is also provided with a charging port 26. By connecting a terminal 6a of an external AC adapter 6 to a terminal within this charging port 26, it becomes possible to operate using an external power source and charge the internal battery. The terminal 6a is, for example, a USB (Universal Serial Bus) Type-C connector, and the terminal 6a and the charging port are configured to comply with the USB-PD (USB Power Delivery) standard.

[0020] <2. Internal structure> The internal configuration of the drone 2 and the control device 1 will be described with reference to FIG. The drone 2 is equipped with an aerial station 80, a camera 82, a flight controller 83, and antennas 84 and 85.

[0021] The aerial station 80 communicates with the pilot device 1 and processes information transmission to a camera 82 and a flight controller 83 based on the communication. The flight controller 83 controls the flight of the drone 2 and performs sensing using various sensors. The camera 82 captures an image and outputs an image signal SV0. The camera 82 is provided with a gimbal mechanism (not shown).

[0022] The antenna 84 is a first communication antenna used for the first wireless communication, which is a one-way communication in the 5.7 GHz band. The antenna 85 is a second communication antenna used for a second wireless communication, which is simplex communication in the sub-GHz band.

[0023] The aerial station 80 supplies the control signal CM transmitted from the controller 1 by the second wireless communication to the camera 82 (or gimbal mechanism). This causes the camera operation or gimbal operation to be performed in response to the user's operation on the controller 1 side. The aerial station 80 also supplies the control signal CM and the request signal transmitted from the control device 1 through the second wireless communication to the flight controller 83. This allows the drone 2 to fly in response to the operation of the user on the control device 1 side, and transmits the telemetry data TM in response to the request signal.

[0024] The aerial station 80 also performs processing to transmit an image signal SV0 captured by a camera 82 from an antenna 84 via a first wireless communication. The aerial station 80 also performs a process of transmitting the telemetry data TM input from the flight controller 83 from the antenna 85 via a second wireless communication.

[0025] The control device 1 includes a ground station 50, a memory unit 70, an operation unit 75, dipole antennas 21, 22, and 23, patch antennas 24 and 25, a battery 77, and a power supply circuit 76.

[0026] In the pilot control device 1, of the three dipole antennas 21, 22, and 23, the dipole antenna 23 is set as a second communication antenna used for the second wireless communication. In addition, the dipole antennas 21, 22 and the patch antennas 24 and 25 are set as a first communication antenna used for the first wireless communication.

[0027] The memory unit 70 has the memory card 5 shown in FIG.

[0028] The operation unit 75 is composed of various operation switches provided on the control device 1, operators such as a joystick, and operation detection circuits for these.

[0029] The ground station 50 receives image signals using a first communication antenna (dipole antennas 21, 22 and patch antennas 24, 25) and receives telemetry data TM using a second communication antenna (dipole antenna 23), and transmits control signals CM and request signals.

[0030] The ground station 50 can transmit the received image signal SV1 to the tablet PC 3 via the terminal 71. For example, the ground station 50 selects the one with the better reception condition between the dipole antenna 21 and the patch antenna 24, and also selects the one with the better reception condition between the dipole antenna 22 and the patch antenna 25. The ground station 50 then performs image synthesis on the selected received signals. For example, synthesis is performed for each frame of the image signal, in pixel block units or line units, such that the one with the least errors or missing pixels is selected. Furthermore, the image signal for each frame thus synthesized is subjected to necessary processing such as adding an on-screen display (OSD) display and changing the resolution, and is output as image signals SV1, SV2, and SV3.

[0031] For example, the ground station 50 supplies an image signal SV1 from a terminal 71 to the tablet PC 3. The ground station 50 can also demodulate telemetry data TM received by the dipole antenna 23 and transmit the data to the tablet PC 3 via a terminal 72. As a result, on the tablet PC 3 side, an application program corresponding to the pilot device 1 is started, so that the input image signal SV1 and telemetry data TM can be processed and displayed on the display screen 30. Therefore, the user can pilot the drone 2 and operate the camera while viewing the images captured by the drone 2 and the telemetry data on the display screen 30.

[0032] In the ground station 50, the reception process of the telemetry data TM and the reception process of the image signal are performed asynchronously.

[0033] Moreover, the ground station 50 can supply the received image signal SV2 to the storage unit 70 so that it can be stored in the memory card 5. Furthermore, the ground station 50 can supply the received image signal SV3 to a terminal 73. When the monitor device 4 is connected to the terminal 73, the image captured by the drone 2 is displayed on the monitor device 4.

[0034] When transmitting a control signal or a request signal in response to an operation of the operation unit 75 , the ground station 50 modulates data as the control signal or the like and transmits the signal from the dipole antenna 23 .

[0035] The battery 77 is an internal battery of the control device 1 and is composed of, for example, a lithium-ion battery. The power supply circuit 76 supplies an operating power supply voltage, for example, DC 8.5 V, to each part of the pilot device 1 using the power supply voltage from a battery 77 or the power supply voltage from an external power supply via an AC adapter 6 connected to the charging port 26. The power supply circuit 76 also charges the battery 77.

[0036] <3. Comparative Example> Below, we will mainly explain power supply circuit 76, but first, a power supply circuit 200 as a comparative example is shown in Fig. 3. Power supply circuit 200 as the comparative example is an example configuration assuming power supply from an external power source, power supply from battery 77, and charging of battery 77 in pilot device 1.

[0037] The power supply circuit 200 includes a power on / off control unit 40, a USB-PD detection unit 41, a charging circuit 42, a power supply switching unit 43, and a DC / DC converter 44.

[0038] The USB-PD detection unit 41 detects a power supply voltage based on an external power supply from the AC adapter 6, for example, an input of DC 5V, and outputs a control signal to the power on / off control unit 40 in response to the input of DC 5V.

[0039] In response to a control signal from the USB-PD detection unit 41, the power on / off control unit 40 turns on the power supply voltage (DC 5V) from the AC adapter 6, that is, supplies the power supply voltage (DC 5V) to the power supply switching unit 43.

[0040] The power supply switching unit 43 has one terminal P1 supplied with a power supply voltage (DC 5V) from the AC adapter 6, and the other terminal P2 supplied with a power supply voltage, for example DC 7.2V, from the battery 77.

[0041] The power supply switching unit 43 also receives the power supply voltage (DC 5V) output from the power on / off control unit 40 as a control signal S1. That is, when the power on / off control unit 40 is turned on and the power supply voltage (DC 5V) is supplied as the control signal S1, the power supply switching unit 43 performs switching to select terminal P1. On the other hand, when the power on / off control unit 40 is turned off and the power supply voltage (DC 5V) is not supplied, the power supply switching unit 43 selects terminal P2.

[0042] The power supply voltage (DC 5V or DC 7.2V) output from the power supply switching unit 43 is input to the DC / DC converter 44. The DC / DC converter 44 boosts the input voltage and generates an output voltage of DC 8.5V, for example. This DC 8.5V is supplied to a power supply voltage line 91 as an operating power supply voltage for each part in the control device 1 shown as a load 90. Note that the load 90 in the control device 1 is assumed to consume a relatively large amount of power, about 10W.

[0043] The charging circuit 42 supplies a charging current to the battery 77 in response to the power on / off control unit 40 being turned on and the power supply voltage (DC 5V) being supplied.

[0044] According to the power supply circuit 200 of this comparative example, the pilot device 1 can be operated by switching between the battery 77 and an external power supply. When a power supply voltage (DC 5V) is supplied from the AC adapter 6, the power supply voltage (DC 5V) is used to supply a power supply voltage of DC 8.5V to the load 90 and to charge the battery 77. When the power supply voltage (DC 5V) is not supplied from the AC adapter 6, the power supply voltage (DC 7.2V) from the battery 77 is used to supply a power supply voltage of DC 8.5V to the load 90.

[0045] However, in such a power supply circuit 200, the following phenomenon occurred. When the power supply switching unit 43 switches from the external power supply to the battery 77, the AC adapter 6 is overloaded, and the output of the power supply switching unit 43 becomes unstable. This causes the downstream DC / DC converter 44 to be unable to generate the power supply voltage (DC 8.5 V) normally.

[0046] This is shown in Fig. 4. Fig. 4 shows the power supply voltage (DC 5V) from the AC adapter 6 as an external power supply, detection by the USB-PD detection unit 41, internal DC 5V (power supply voltage (DC 5V) supplied to the power supply switching unit 43), and the power supply switching output (output state of the power supply switching unit 43).

[0047] Assume that at time t0, for example, the AC adapter 6 is connected and the power supply voltage (DC 5V) is input to the power on / off control unit 40. It is assumed that the USB-PD detection unit 41 has completed detection of the supply of DC 5V from the AC adapter 6 during the period from time t0 to time t1. This turns on the power on / off control unit 40, and the internal DC 5V is applied to terminal P1 of the power supply switching unit 43. At the same time, the power supply switching unit 43 switches the connection terminal from terminal P2 to terminal P1 in response to the control signal S1.

[0048] However, at this time, the power supply voltage (DC 5V) becomes unstable due to the overload. In other words, the power supply switching output was stable at the power supply voltage (DC 7.2V) from the battery 77 until time t1, but became unstable after time t1, and as a result, the power supply voltage (DC 8.5V) cannot be generated normally by the DC / DC converter 44.

[0049] Furthermore, with the power supply circuit 200, a problem also occurs when the supply of power supply voltage (DC 5V) from the AC adapter 6 is cut off. When the USB-PD detection unit 41 detects that the power supply voltage (DC 5V) is not being supplied from the AC adapter 6, the power on / off control unit 40 turns off, and the power supply switching unit 43 switches to the P2 terminal in response to the control signal S1. At this point, a voltage drop occurs. As a result, the DC / DC converter 44 in the downstream stage cannot generate the power supply voltage (DC 8.5V) normally, resulting in an instantaneous power interruption.

[0050] This is shown in Figure 5. Assume that at time t10, the AC adapter 6 is connected and the power source switching unit 43 switches from the battery 77 (terminal P2) to the external power source (terminal P1). Then, at time t11, the power source voltage (DC 5V) is no longer supplied from the AC adapter 6. At this time, power supply switching unit 43 switches to terminal P2, but a voltage drop occurs at the output of power supply switching unit 43, which in turn causes a voltage drop for a period of, for example, about 20 msec at the output of DC / DC converter 44, causing a momentary interruption in load 90.

[0051] <4. Power supply circuit according to the embodiment> In consideration of the above-mentioned inconveniences, the power supply circuit 76 according to the embodiment is configured as shown in FIG.

[0052] 6 also includes a power on / off control unit 40, a USB-PD detection unit 41, a charging circuit 42, a power switching unit 43, and a DC / DC converter 44, as in the comparative example of FIG. In addition, the power supply circuit 76 includes a switching delay circuit 45 , an external power supply detection section 46 , a complement control section 47 , a complement circuit 48 , and a Schottky barrier diode 49 .

[0053] A reset IC that receives a predetermined voltage and outputs a delayed reset output signal is used for the switching delay circuit 45. The delay time can be set by a capacitor 45c that is connected to a predetermined terminal of the reset IC. The switching delay circuit 45 using such a reset IC receives the power supply voltage (DC 5V) from the power on / off control unit 40 and outputs a delayed version of it as a control signal S2 for the power supply switching unit 43.

[0054] The external power supply detection unit 46 detects the power supply voltage (DC 5V) from the power on / off control unit 40 and supplies a detection signal to the complementary control unit 47. The complement control unit 47 is configured by, for example, a CPU (Central Processing Unit), and provides a control signal S3 to the complement circuit 48 to perform on / off control.

[0055] The complement circuit 48 has a switch for turning on / off the power supply voltage (DC 7.2 V) from the battery 77 . When the complement circuit 48 is turned on, the power supply voltage (DC 7.2 V) from the battery 77 is applied via the Schottky barrier diode 49 to the output side of the DC / DC converter 44 , that is, to the power supply voltage line 91 for the load 90 .

[0056] In such a power supply circuit 76, first, when switching to power supply from the AC adapter 6, the switching delay circuit 45 functions to eliminate the unstable operation described with reference to FIG.

[0057] This will be explained with reference to Fig. 7. Fig. 7 shows the power supply voltage (DC 5V) from the AC adapter 6 shown in Fig. 4, the detection by the USB-PD detection unit 41, the internal DC 5V (the power supply voltage (DC 5V) supplied to the power supply switching unit 43), and the power supply switching output (the output state of the power supply switching unit 43), as well as the control signal S2.

[0058] Assume that at time t20, for example, the AC adapter 6 is connected and the power supply voltage (DC 5V) is input to the power on / off control unit 40. Also assume that the USB-PD detection unit 41 detects the supply of DC 5V from the AC adapter 6, and completes detection of the DC 5V supply at time t21. This causes the power on / off control unit 40 to be turned on, and the internal DC 5V is applied to terminal P1 of the power switching unit 43. However, at this time t21, the control signal S2 is not on, so the power supply switching unit 43 maintains the connection of the terminal P2. Therefore, the output of the power supply switching unit 43 remains the power supply voltage (DC 7.2 V) from the battery 77.

[0059] The internal DC 5V from the power on / off control unit 40 is also supplied to the switching delay circuit 45. The switching delay circuit 45 outputs the internal DC 5V as the control signal S2 with a delay time of, for example, 500 msec set by the capacitor 45c. As a result, at the time t22, 500 msec after the time t21, the control signal S2 is turned on, and the power switching unit 43 is switched to the terminal P1. After time t22, the output of the power supply switching unit 43 becomes the power supply voltage (DC 5V) from the AC adapter 6.

[0060] In the above operation, the switching delay circuit 45 is used to stabilize the output of the AC adapter 6 before switching of the power supply switching unit 43 is performed. Even if a power supply voltage (DC 5V) is input from the AC adapter 6, by waiting for, for example, 500 msec, the power supply voltage (DC 5V) is stabilized, and switching of the power supply switching unit 43 is performed after stabilization. This allows the power supply switching unit 43 to obtain a stable DC 5V output at time t22, and this can be supplied to the DC / DC converter 44.

[0061] Next, the operation when switching power supply from the AC adapter 6 to the battery 77 will be described with reference to FIG. 8 shows the power supply voltage (DC 5V) from the AC adapter 6, the power supply voltage (DC 8.5V) that is the output from the DC / DC converter 44, and the control signal S3 from the complementary control unit 47.

[0062] Assume that the AC adapter 6 is connected at time t30, and the power source switching unit 43 switches from the battery 77 (terminal P2) to the external power source (terminal P1). Then, at time t31, for example, the connection with the AC adapter 6 is released, and the power source voltage (DC 5V) is no longer supplied from the AC adapter 6.

[0063] Looking at the control signal S3, it is ON while the power supply voltage (DC 5V) is being supplied from the AC adapter 6, and it remains ON for a period of 500 msec even after the power supply voltage (DC 5V) is interrupted. After this period of 500 msec has elapsed, the control signal S3 is turned OFF. While the control signal S3 is on, the complement circuit 48 is turned on, and the line of the power supply voltage (DC 7.2 V) from the battery 77 is connected to the power supply voltage line 91 via the Schottky barrier diode 49.

[0064] The power supply voltage line 91, which is the output side of the DC / DC converter 44, is set to the power supply voltage (DC 8.5 V). However, as described above with reference to FIG. 5, a voltage drop occurs when the power supply voltage (DC 5 V) from the AC adapter 6 is interrupted. In the case of FIG. 8, this timing is between time t31 and time t32, and during this period, the power supply voltage line 91 is supplemented with DC 7.2V from the battery 77.

[0065] When the DC / DC converter 44 is functioning normally and outputting 8.5V, the Schottky barrier diode 49 does not conduct, and therefore no current flows from the power supply voltage line 91 to the battery 77. When the output voltage of the DC / DC converter 44 drops and the Schottky barrier diode 49 conducts, the power supply voltage (DC 7.2V) is used to supplement the output.

[0066] As described above, the power supply circuit 76 according to the embodiment can solve the problems that occur during switching in the power supply circuit 200 of the comparative example, and can achieve a stable supply of power supply voltage. When the power supply voltage (DC 7.2V) of the battery 77 is input to the DC / DC converter 44, the complement circuit 48 is turned off, thereby preventing DC 8.5V from leaking to the battery 77 side.

[0067] An example of processing by the complementary control unit 47 (CPU) for realizing such an operation is shown in Fig. 9. The complementary control unit 47 repeatedly executes the processing in Fig. 9 as processing at predetermined time intervals, for example.

[0068] In step S101, the complement control unit 47 detects a signal from the external power source detection unit 46 and determines whether or not the power source voltage (DC 5V) from the AC adapter 6 is detected. When the power supply voltage (DC 5V) is detected, the complement control unit 47 proceeds to step S102, turns on the control signal S3, and turns on the flag Fs used in the processing in step S103.

[0069] When the power supply voltage (DC 5V) is not detected, the complement control unit 47 proceeds from step S101 to step S104, and branches the process according to the flag Fs. For example, when the external power supply is cut off, such as at time t31 in Fig. 8, the flag Fs is on. In this case, the complement control unit 47 performs a count process, for example, incrementing a count variable, in step S105.

[0070] In step S106, the complement control unit 47 determines whether the count value is equal to or greater than a predetermined threshold value th1. The threshold value th1 is a count value equivalent to, for example, 500 msec. If the count value is not equal to or greater than the threshold value th1, the process of Fig. 9 ends, and the process returns to step S101. For example, the above process is repeated from time t31 to time t33 in Fig. 8.

[0071] When the count value becomes equal to or greater than the threshold value th1 at a certain point in time in step S106, the complement control unit 47 proceeds to step S107 to turn off the flag Fs, and turns off the control signal S3 at step S108. This is the process at time t33, for example.

[0072] Thereafter, if the state in which the power supply voltage (DC 5V) is not detected continues, the complement control unit 47 proceeds from step S104 to step S108 since the flag Fs is off, and keeps the control signal S3 off.

[0073] Further thereafter, when the power supply voltage (DC 5V) from the AC adapter 6 is detected, the complement control unit 47 proceeds from step S101 to step S102, turns on the control signal S3, and turns on the flag Fs. Thereafter, this is repeated until the power supply voltage (DC 5V) from the AC adapter 6 is no longer detected.

[0074] 5. Effects of the embodiment and modifications According to the above embodiment, the following effects can be obtained.

[0075] The power supply circuit 76 of the embodiment includes a power supply switching unit 43 that selectively outputs a power supply voltage (DC 7.2 V) from a battery 77 and a power supply voltage (DC 5 V) from an AC adapter 6, and a DC / DC converter 44 that receives the power supply voltage from the power supply switching unit 43 and outputs a power supply voltage of a predetermined voltage value (8.5 V) to a power supply voltage line 91 for a load 90. The power supply circuit 76 further includes a switching delay circuit 45 that controls the power supply switching unit 43 so that the power supply voltage (DC 7.2 V) from the battery 77 is output during a period when a power supply voltage input from the AC adapter 6 is not detected, and when a power supply voltage input from the AC adapter 6 is detected, the power supply circuit 76 outputs the power supply voltage (DC 5 V) from the AC adapter after a predetermined delay time has elapsed. As a result, the power supply voltage is switched after the power supply voltage output from the AC adapter 6 has stabilized, and unstable operation when the power supply is switched to the AC adapter 6 can be avoided. Although the switching delay circuit 45 outputs the control signal S2 delayed by 500 msec, the delay time does not have to be 500 msec. It is sufficient if the delay time allows the switching to wait until the power supply voltage output from the AC adapter 6 becomes stable.

[0076] In addition, in the embodiment, the switching delay circuit 45 is configured with an IC that outputs an output with a delay time set by the connected capacitor 45c to the power supply voltage (DC 5V) from the AC adapter 6 as a control signal S2 to the power supply switching unit 43. This makes it possible to realize, with a simple circuit, the switching delay circuit 45 that causes the power supply switching unit 43 to execute switching after a delay time has elapsed when the supply of power supply voltage from the AC adapter 6 is started.

[0077] Moreover, in addition to the power supply switching unit 43 and the DC / DC converter 44, the power supply circuit 76 of the embodiment includes a complement circuit 48 that can turn on / off the application of the power supply voltage (DC 7.2 V) from the battery 77 to the power supply voltage line 91, and a complement control unit 47 that turns on the complement circuit 48 while the power supply voltage input from the AC adapter 6 is detected, and controls the complement circuit 48 to be turned off after a predetermined time has elapsed when the power supply voltage input from the AC adapter 6 is no longer detected. This makes it possible to prevent momentary power outages caused by voltage drops, since the power supply voltage from the battery 77 is supplemented when the AC adapter 6 is removed, etc. Note that although 500 msec is given as the predetermined time, this is merely an example and does not have to be 500 msec. The predetermined time should be set so that the period during which the voltage drop occurs can be covered by the supplementary voltage.

[0078] In the embodiment, the power supply voltage (DC 7.2V) from the battery 77 that is output when the complement circuit 48 is turned on is applied to the power supply voltage line 91 via a backflow prevention element. By using a backflow prevention element such as a Schottky barrier diode 49, even if the complement circuit 48 is turned on, no current flows back from the power supply voltage line 91 to the battery 77, and when a voltage drop occurs, the voltage of the power supply voltage line 91 is complemented by the power supply voltage from the battery 77. Furthermore, if the supplementary circuit 48 is always on when power voltage is being supplied by the AC adapter 6, the power voltage can be appropriately supplemented by the battery 77 when the power supply from the AC adapter 6 is suddenly cut off.

[0079] The configuration example of FIG. 6 includes a switching delay circuit 45, an external power supply detection unit 46, a complement control unit 47, a complement circuit 48, and a Schottky barrier diode 49. The configuration is not limited to this, and there is also a configuration example that has the switching delay circuit 45 but does not include the external power supply detection unit 46, the complementary control unit 47, the complementary circuit 48, and the Schottky barrier diode 49. In other words, this is at least a configuration example that eliminates unstable operation when switching to power supply from the AC adapter 6 as shown in FIG. Alternatively, there is a configuration example in which the switching delay circuit 45 is not provided, but an external power supply detection unit 46, a complementary control unit 47, a complementary circuit 48, and a Schottky barrier diode 49 are provided. In other words, this is a configuration example in which an instantaneous power interruption does not occur at least when switching to power supply from the battery 77 as shown in FIG.

[0080] In the embodiment, the power supply circuit 76 built into the control device 1 is taken as an example. The control device 1 is equipped with a ground station 50 that simultaneously executes a first wireless communication, which is a one-way communication in a first frequency band, and a second wireless communication, which is a simplex communication in a second frequency band lower than the first frequency band, with an unmanned mobile body, receives an image signal captured by a camera attached to the unmanned mobile body by the first wireless communication, and transmits a control signal to the unmanned mobile body and receives telemetry data from the unmanned mobile body by the second wireless communication. When using either the AC adapter 6 or the battery 77 in such a control device 1, the power supply circuit 76 can maintain a stable power supply voltage state even when switching, regardless of whether the AC adapter 6 is plugged in or unplugged, thereby improving the control function of the unmanned vehicle and the stability of image display. In particular, in the case of such a control device 1, a relatively large power consumption of about 10 W is assumed for the load 90. The power supply circuit 76 is suitable for such a device.

[0081] The communication system exemplified in the embodiment is a communication system between a drone 2, which is an unmanned mobile body, and a control device 1. This communication system simultaneously executes a first wireless communication in which an image signal captured by a camera 82 attached to the drone 2 is transmitted to the control device 1 by one-way communication in a first frequency band, and a second wireless communication in which a control signal is transmitted from the control device 1 to the drone 2 and telemetry data is transmitted from the drone 2 to the control device 1 by simplex communication in a second frequency band. In such a communication system, image signals, which have a large data size, can be separated from telemetry data and control signals, thereby stabilizing the transmission of both. In addition, image signals are transmitted in a high-frequency band, which is advantageous in terms of transfer rate, and image transmission can be stabilized. In particular, the first wireless communication is one-way, which allows the control device 1 to increase the reception gain and improve the reception sensitivity of image signals from long distances, resulting in excellent stable image display.

[0082] Specifically, using the 5.7 GHz band for the first wireless communication is suitable for transmitting and receiving a large amount of data for images because it provides a sufficient bandwidth. Communication of control signals and telemetry data uses the sub-GHz band because the amount of data is small but long-distance compatibility and good communication performance are required. By using each of these frequency bands, it is possible to optimally realize image transmission, telemetry data transmission, and control functions.

[0083] In particular, when flying the drone 2 up to a distance of, for example, about 5 km, the user will operate the drone 2 while looking at the captured images. For this reason, stability of image communication over long distances is extremely desirable in the communication system between the aircraft and the control device.

[0084] The pilot device 1 also includes a ground station 50 that simultaneously processes the first and second wireless communications, a first communication antenna (21, 22, 24, 25) used to receive the first wireless communication, and a second communication antenna (23) used to transmit and receive the second wireless communication. In this case, the first communication antenna is dedicated to reception, allowing the reception gain to be set high, making it suitable for long-distance image transmission.

[0085] In the above, a drone is used as an example of an unmanned mobile body; however, in the present invention, unmanned mobile bodies are not limited to unmanned aerial vehicles such as drones, and may take forms other than aerial vehicles, such as unmanned ground vehicles, unmanned surface ships, unmanned surface boats, and unmanned submarine boats. [Explanation of symbols]

[0086] 1. Controls 2. Drone 6 AC adapter 26 Charging port 40 Power On / Off Control Unit 41 USB-PD detector 42 Charging circuit 43 Power Switching Unit 44 DC / DC converter 45 Switching Delay Circuit 45c capacitor 46 External power supply detection section 47 Complementary control unit (CPU) 48 Complementary Circuit 49 Schottky Barrier Diode 50 Ground Station 76 Power supply circuit 77 Battery 90 Load 91 Power supply voltage line

Claims

1. a power supply switching unit that selectively outputs a power supply voltage from an internal battery and a power supply voltage from an AC adapter; a DC / DC converter that receives a power supply voltage from the power supply switching unit and outputs a power supply voltage of a predetermined voltage value to a power supply voltage line for a load; a switching delay circuit that controls the power supply switching unit so as to output a power supply voltage from the internal battery during a period when a power supply voltage input from the AC adapter is not detected, and to output the power supply voltage from the AC adapter after a predetermined delay time has elapsed when a power supply voltage input from the AC adapter is detected; a complement circuit that can turn on / off application of the power supply voltage from the internal battery to the power supply voltage line; a complement control unit that turns on the complement circuit during a period when a power supply voltage input from the AC adapter is detected, and that controls to turn off the complement circuit after a predetermined time has elapsed when the power supply voltage input from the AC adapter is no longer detected. power circuit.

2. a power supply switching unit that selectively outputs a power supply voltage from an internal battery and a power supply voltage from an AC adapter; a DC / DC converter that receives a power supply voltage from the power supply switching unit and outputs a power supply voltage of a predetermined voltage value to a power supply voltage line for a load; a switching delay circuit that controls the power supply switching unit so that a power supply voltage from the internal battery is output during a period when a power supply voltage input from the AC adapter is not detected, and when a power supply voltage input from the AC adapter is detected, the power supply voltage from the AC adapter is output after a predetermined delay time has elapsed. power circuit.

3. a power supply switching unit that selectively outputs a power supply voltage from an internal battery and a power supply voltage from an AC adapter; a DC / DC converter that receives a power supply voltage from the power supply switching unit and outputs a power supply voltage of a predetermined voltage value to a power supply voltage line for a load; a complement circuit that can turn on / off application of the power supply voltage from the internal battery to the power supply voltage line; a complement control unit that turns on the complement circuit during a period when a power supply voltage input from the AC adapter is detected, and that controls to turn off the complement circuit after a predetermined time has elapsed when the power supply voltage input from the AC adapter is no longer detected. power circuit.

4. The switching delay circuit is configured with an IC that outputs an output, to which the delay time set by a connected capacitor is applied to the power supply voltage from the AC adapter, as a control signal for the power supply switching unit.

3. The power supply circuit according to claim 1 or 2.

5. The power supply voltage from the internal battery, which is output when the complement circuit is turned on, is applied to the power supply voltage line via a backflow prevention element. The power supply circuit according to claim 1 or 3.

6. The control device is built in a ground station that simultaneously executes a first wireless communication, which is a one-way communication in a first frequency band, and a second wireless communication, which is a simplex communication in a second frequency band lower than the first frequency band, with an unmanned vehicle, receives an image signal captured by a camera attached to the unmanned vehicle by the first wireless communication, and transmits a control signal to the unmanned vehicle and receives telemetry data from the unmanned vehicle by the second wireless communication. The power supply circuit according to any one of claims 1 to 3.

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