JP7309082B2 - hand dryer - Google Patents

Description

The present disclosure relates to hand dryers for drying wet hands.

Hand hygiene requires proper washing of hands and hygienic drying of wet hands after washing. In order to enable sanitary drying of the hands, a hand drying device is sometimes used that dries the hands by blowing off water droplets with jets of air.

When a hand is detected at the hand insertion portion of the hand dryer, the hand dryer activates the blower to blow airflow at the hand insertion portion. When the hand is removed from the hand insertion portion and the hand is no longer detected, the hand dryer stops the blower. Hand dryers are required to be able to shorten the time from the detection of the hand to the activation of the blower. In addition, the hand dryer is required to be able to reduce the standby power consumption while the blower is stopped.

In addition, a drive circuit including an inverter circuit and a bootstrap circuit may be used in an air blower having a direct current (DC) brushless motor as a drive source. A bootstrap circuit is connected to the drive circuit. Operation of the drive circuit begins through charging of the capacitor in the bootstrap circuit.

Patent Literature 1 discloses a blower provided with a boost converter section that boosts an AC voltage supplied from an AC power source and converts it into a DC voltage. The blower can be downsized and can increase the amount of air blown by boosting the air in the boosting converter section.

Japanese Patent No. 5158101

The hand dryer is required to start blowing air immediately after the hand is detected. According to the conventional technology disclosed in Patent Document 1, the hand dryer boosts the DC voltage until it reaches a desired voltage value after the hand is detected. In the case of a hand dryer that uses a bootstrap circuit, charging the bootstrap circuit after the bus voltage has stabilized delays start-up of the blower for the period of waiting for the completion of boosting and the completion of charging. Become. On the other hand, if the step-up converter section is operated all the time in order to shorten the time until the blower starts up, the standby power consumption of the hand dryer increases. Hand dryers are required to be able to shorten the period required to start air blowing and to reduce standby power consumption.

The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain a hand dryer that can shorten the time required to start air blowing and reduce standby power consumption.

In order to solve the above-described problems and achieve the object, the hand dryer according to the present disclosure includes a housing having a hand insertion portion, an air blower for sending out an air flow to be jetted from the hand insertion portion, and a hand insertion portion. a hand detection unit for detecting a hand inserted into the body; a power supply unit including a booster circuit for boosting DC voltage; a drive circuit for receiving power from the power supply unit to drive the blower unit; and a bootstrap circuit. The drive circuit can drive the blower after charging the bootstrap circuit. The booster circuit starts boosting when the hand is detected by the hand detector. The charging of the bootstrap circuit is performed during the boosting period.

The hand dryer according to the present disclosure has the effect of shortening the time required to start air blowing and reducing standby power consumption.

A perspective view of a hand dryer according to the first embodiment Sectional view of the hand dryer according to the first embodiment FIG. 3 is a diagram showing the configuration of a control unit included in the hand dryer according to the first embodiment; FIG. 4 is a diagram showing a configuration of a control unit according to a modification of the first embodiment; FIG. Flowchart showing the operation procedure of the hand dryer according to the first embodiment Timing chart for explaining the relationship between boosting and charging in the hand dryer according to the first embodiment Flowchart showing the operation procedure of the hand dryer according to the second embodiment Timing chart for explaining the relationship between boosting and charging in the hand dryer according to the second embodiment Flowchart showing the operation procedure of the hand dryer according to the third embodiment Timing chart for explaining the operation of the hand dryer according to the third embodiment Flowchart showing the operation procedure of the hand dryer according to the fourth embodiment Timing chart for explaining the operation of the hand dryer according to the fourth embodiment Flowchart showing the operation procedure of the hand dryer according to the fifth embodiment

A hand dryer according to an embodiment will be described in detail below with reference to the drawings.

Embodiment 1.
FIG. 1 is a perspective view of a hand dryer 1 according to Embodiment 1. FIG. FIG. 2 is a cross-sectional view of the hand dryer 1 according to the first embodiment. FIG. 2 shows a cross section taken along line II--II of FIG.

A hand dryer 1 has a housing 3 having a hand insertion portion 2 into which a hand can be inserted. The upper portion and both side portions of the hand insertion portion 2 are open. A hand can be inserted into the hand insertion part 2 from the upper part and both sides. The housing 3 forms the outer shell of the hand dryer 1 as a whole. The front part 4 is a part of the housing 3 and is a part on the front side of the hand insertion part 2 . The back portion 5 is a part of the housing 3 and is a portion on the back side of the hand insertion portion 2 . Note that the front side is the side where the user using the hand dryer 1 is located when viewed from the hand dryer 1 . The back side is the side opposite to the front side when viewed from the hand dryer 1 .

The water receiving portion 6 is positioned at the bottom of the hand inserting portion 2 . The water receiving portion 6 is provided with a drain port for discharging the received water to the drain tank 7 . Further, the housing 3 is provided with a drainage channel through which water from the drainage port flows to the drain tank 7 . Illustration of the drain port and the drain channel is omitted. The drain tank 7 stores water from the drainage channel. The drain tank 7 is provided on the front side of the lower portion of the housing 3 . The drain tank 7 is detachable from the housing 3.

The hand dryer 1 includes an air blower 10 that is a blower that blows out an airflow that is jetted from the hand insertion portion 2 . The blower 10 is provided inside the housing 3 . The blower 10 includes a DC brushless motor 21 as a drive source and a turbo fan 22 that is driven by the DC brushless motor 21 to rotate.

The nozzle 11 is provided on the surface of the front portion 4 on the side of the hand insertion portion 2 . The nozzle 12 is provided on the surface of the back portion 5 on the side of the hand insertion portion 2 . The hand dryer 1 causes the hand inserting portion 2 to jet the airflow that has passed through the duct 13 inside the front portion 4 from the blower 10 from the nozzle 11 . The hand dryer 1 causes the hand insertion portion 2 to jet the airflow that has passed through the duct 14 inside the back portion 5 from the blower 10 from the nozzle 12 .

The hand dryer 1 includes a sensor 15 that is a hand detection section that detects a hand inserted into the hand insertion section 2 . The sensor 15 is built in the back portion 5 . One example of sensor 15 is a ranging sensor. The sensor 15, which is a distance measuring sensor, includes a light-emitting element that emits infrared light and a light-receiving element that detects infrared light reflected by a hand, which is an object to be measured. Illustration of the light-emitting element and the light-receiving element is omitted. The sensor 15 detects the presence or absence of a hand in the hand insertion portion 2 based on the angle of the infrared light incident on the light receiving element. The sensor 15 may be any sensor other than a distance measuring sensor as long as it can detect the hand inserted into the hand insertion portion 2 . The sensor 15 may be built in the front portion 4 .

The intake port 16 is provided at a rear side position in the lower portion of the housing 3 . The blower 10 takes in an airflow from an air inlet 16 to a duct 17 inside the housing 3 and sends out the airflow from the duct 17 to the ducts 13 and 14 . An air filter 18 is attached to the intake port 16 to remove foreign matter from the airflow taken into the duct 17 . In addition, the hand dryer 1 may be provided with a heater for heating the air flow sent out to the ducts 13 and 14 .

Inside the housing 3, a control unit 20 for controlling the entire hand dryer 1 is provided. When the sensor 15 detects the hand, the control unit 20 activates the blower 10 . When the hand is removed from the hand insertion portion 2 and the hand is no longer detected by the sensor 15 , the control portion 20 stops the blower 10 .

FIG. 3 is a diagram showing the configuration of the controller 20 included in the hand dryer 1 according to the first embodiment. The control unit 20 includes a power supply unit 24 including a booster circuit that boosts a DC voltage, a drive circuit 25 that receives power supply from the power supply unit 24 and drives the DC brushless motor 21, and a microcontroller 26 that is a control processing unit. , a boost converter section 30 which is a booster circuit, and a bootstrap circuit 45 .

The rectifier circuit 31 of the power supply section 24 is connected to the commercial AC power supply 23 . The rectifier circuit 31 outputs a DC voltage by full-wave rectification of the AC voltage from the commercial AC power supply 23 . A voltage dividing resistor 32, which is a voltage detecting means, is connected on the output side of the rectifier circuit 31 between a DC bus 42 on the positive voltage side and a DC bus 43 on the negative voltage side. Inductor 33 , switching element 34 , and fast recovery diode 35 of power supply section 24 constitute boost converter section 30 . The boost converter unit 30 boosts the voltage of the DC voltage from the rectifier circuit 31 until it reaches a predetermined voltage value.

Inductor 33 is connected to DC bus 42 . The switching element 34 is connected between the DC buses 42 and 43 on the output side of the inductor 33 . The switching element 34 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor), which is a semiconductor element having a switching function.

The anode of the fast recovery diode 35 is connected to the output side of the inductor 33 . A voltage dividing resistor 36, which is voltage detection means, is connected between the DC buses 42 and 43 on the cathode side of the fast recovery diode 35. As shown in FIG. A smoothing capacitor 37 is connected between the DC buses 42 and 43 on the output side of the voltage dividing resistor 36 . The control power supply circuit 38 is connected between the DC buses 42 and 43 on the output side of the smoothing capacitor 37 . A resistor 39 serving as current detection means is connected between the voltage dividing resistor 32 and the switching element 34 in the DC bus 43 .

When the switching element 34 is turned on, the inductor 33 is charged. When switching element 34 is switched from on to off, inductor 33 releases the stored charge. The smoothing capacitor 37 is charged by the charge supplied from the inductor 33 through the fast recovery diode 35 . The smoothing capacitor 37 reduces noise by smoothing the voltage.

A switching control IC (Integrated Circuit) 40 controls the switching operation of the switching element 34 . The switching control IC 40 detects the DC voltage output from the rectifier circuit 31 with the voltage dividing resistor 32 . The switching control IC 40 detects the current from the inductor 33 with the resistor 39 . The switching control IC 40 detects the voltage output from the boost converter section 30 with the voltage dividing resistor 36 . The switching control IC 40 controls the operation of the switching element 34 based on the detection results of the voltage dividing resistors 32 and 36 and the resistor 39, thereby matching the phase of the voltage and the phase of the current after rectification.

The switching control IC 40 functions as a power factor correction circuit that brings the power factor of the power supply section 24 closer to 1 by adjusting the phase of the voltage and the phase of the current to match, thereby suppressing the generation of harmonic current components. Boost converter section 30 functions as an active filter for suppressing harmonic current components. Furthermore, the switching control IC 40 controls the operation of the switching element 34 to adjust the voltage value from the boost converter section 30 to a desired voltage value.

Control power supply circuit 38 supplies power to drive circuit 25 , microcontroller 26 , switching control IC 40 and bootstrap circuit 45 . The switching element 41 is a semiconductor element having a switching function and is a bipolar transistor. The switching element 41 is connected to the microcontroller 26 , the control power supply circuit 38 and the switching control IC 40 .

Bootstrap circuit 45 is connected to drive circuit 25 . The switching element 44 is a semiconductor element having a switching function and is a bipolar transistor. Switching element 44 is connected to microcontroller 26 , control power supply circuit 38 and bootstrap circuit 45 .

When the sensor 15 detects a hand, the microcontroller 26 applies current to the base of the switching element 41 to turn on the switching element 41 . When the switching element 41 is turned on, power from the control power supply circuit 38 is supplied to the switching control IC 40 . The switching control IC 40 turns on the switching operation of the switching element 34 by being supplied with power. When the switching operation of switching element 34 is turned on, boost converter section 30 starts boosting. When the voltage output from boost converter section 30 reaches a desired voltage value, control power supply circuit 38 supplies power to drive circuit 25 .

Further, when the hand is detected by the sensor 15, the microcontroller 26 applies current to the base of the switching element 44 to turn on the switching element 44. FIG. When the switching element 44 is turned on, the power of the control power supply circuit 38 is supplied to the bootstrap circuit 45 . The control unit 20 charges the bootstrap circuit 45 by power supply from the control power supply circuit 38 to the bootstrap circuit 45 . The drive circuit 25 drives the DC brushless motor 21 after charging of the bootstrap circuit 45 is completed. In other words, the drive circuit 25 is ready to drive the blower 10 after charging the bootstrap circuit 45 .

The microcontroller 26 controls on/off of boosting by the boost converter section 30 by switching the switching element 41 between on and off. The microcontroller 26 switches the charging of the bootstrap circuit 45 between on and off by switching the switching element 44 between on and off. The microcontroller 26 also performs feedback control of the drive circuit 25 .

Note that the control unit 20 may include the functions of the switching control IC 40 in the functions of the microcontroller 26 . FIG. 4 is a diagram showing the configuration of the control unit 20 according to the modification of the first embodiment.

In a variant, microcontroller 26 controls the switching operation of switching element 34 . The microcontroller 26 detects the DC voltage output from the rectifier circuit 31 with the voltage dividing resistor 32 . Microcontroller 26 senses current from inductor 33 at resistor 39 . The microcontroller 26 detects the voltage output from the boost converter section 30 with the voltage dividing resistor 36 . The microcontroller 26 controls the operation of the switching element 34 based on the detection results of the voltage dividing resistors 32 and 36 and the resistor 39 to match the phase of the voltage and the current after rectification. Furthermore, the microcontroller 26 controls the operation of the switching element 34 to adjust the voltage value from the boost converter section 30 to a desired voltage value. The microcontroller 26 controls switching on and off of boosting by the boost converter section 30 by switching the switching operation of the switching element 34 between ON and OFF.

Next, operation of the hand dryer 1 will be described. In Embodiment 1, the operation of the hand dryer 1 from when the power of the hand dryer 1 is turned on until the drive circuit 25 starts driving the DC brushless motor 21 will be described. FIG. 5 is a flow chart showing operation procedures of the hand dryer 1 according to the first embodiment.

When power is turned on to the hand dryer 1 by connecting it to the commercial AC power supply 23, the hand dryer 1 enters a standby state in step S10. The standby state is a state in which power is supplied to the hand dryer 1 and the driving of the blower 10 is stopped. Standby power, which is power consumption in the standby state, is lower than power consumption when blower 10 is being driven. In the standby state, the hand dryer 1 does not perform boosting by the boost converter section 30 and does not charge the bootstrap circuit 45 .

In step S11, the hand dryer 1 determines whether or not a hand has been detected. The microcontroller 26 obtains a signal from the sensor 15 indicating the detection result. Microcontroller 26 determines whether a hand has been detected based on the acquired signal. If the hand is not detected (step S11, No), the hand dryer 1 repeats the procedure of step S11. When a hand is detected (step S11, Yes), the hand dryer 1 advances the procedure to step S12 and step S13.

In step S12, the microcontroller 26 turns on the switching element 41, so that the boost converter section 30 starts boosting. Also, in step S13, the microcontroller 26 turns on the switching element 44, so that the hand dryer 1 starts charging the bootstrap circuit 45. As shown in FIG. Microcontroller 26 turns on switching element 41 and switching element 44 at the same time. Boost converter section 30 starts boosting when sensor 15 detects a hand. Charging of the bootstrap circuit 45 is started simultaneously with the start of boosting. The charging of the bootstrap circuit 45 is performed during the boosting period.

In step S14, the hand dryer 1 determines whether or not boosting by the boosting converter section 30 has been completed. Completing the step-up means that the voltage value of the DC voltage reaches a predetermined voltage value. If boosting by the boosting converter unit 30 is not completed (step S14, No), step S14 is repeated. In step S15, the hand dryer 1 determines whether charging of the bootstrap circuit 45 is completed. Completion of charging means that electric charge is accumulated in the capacitor in the bootstrap circuit 45 and no current flows through the capacitor. If charging of the bootstrap circuit 45 is not completed (step S15, No), step S15 is repeated.

When the boosting by the boost converter unit 30 is completed (step S14, Yes) and the charging of the bootstrap circuit 45 is completed (step S15, Yes), the drive circuit 25 starts operating in step S16. As described above, the hand dryer 1 starts driving the DC brushless motor 21 by the driving circuit 25 .

FIG. 6 is a timing chart for explaining the relationship between boosting and charging in the hand dryer 1 according to the first embodiment. The "bus voltage" graph represents changes in bus voltage over time. The bus voltage is the voltage between the DC bus 42 and the DC bus 43 . The "charging voltage" graph represents changes in the charging voltage of the bootstrap circuit 45 on the time axis. The charging voltage is the terminal voltage of the capacitor within the bootstrap circuit 45 .

FIG. 6 shows a "bus voltage" graph and a "charging voltage" graph for two cases. Case 1A is a case in which charging of the bootstrap circuit 45 is started when the bus voltage becomes a constant voltage value due to boosting. Case 1B is a case in which charging of the bootstrap circuit 45 is started simultaneously with the start of boosting by the boost converter section 30 .

In case 1A, the hand dryer 1 is powered on at time t1. After that, when the hand is detected by sensor 15, hand dryer 1 starts boosting by boost converter 30 at time t2. Boosting is completed when the bus voltage reaches a preset voltage value. The hand dryer 1 starts charging the bootstrap circuit 45 when the boosting is completed. The drive circuit 25 starts driving the DC brushless motor 21 at time t3 when the charging of the bootstrap circuit 45 is completed.

In case 1B, as in case 1A, it is assumed that power is turned on to hand dryer 1 at time t1, and boosting by boost converter section 30 is started at time t2. In case 1B, hand dryer 1 also begins charging bootstrap circuit 45 at time t2. Charging is completed before boosting is completed. Drive circuit 25 starts driving DC brushless motor 21 at time t4 when boost converter section 30 completes boosting.

In the case 1B, the hand dryer 1 can start driving the DC brushless motor 21 earlier by Δt1 than in the case 1A. Δt1 is the period from time t4 to time t3. Thus, the hand dryer 1 can start air blowing earlier in case 1B than in case 1A.

According to the first embodiment, the hand dryer 1 starts charging the bootstrap circuit 45 at the same time when the boosting converter unit 30 starts boosting, thereby charging the bootstrap circuit 45 during the boosting period. conduct. As a result, the hand dryer 1 can shorten the time required to start air blowing. Moreover, the hand dryer 1 can reduce standby power consumption by not boosting the pressure in the standby state before the hand is detected. As described above, the hand dryer 1 can shorten the time required to start air blowing, and can reduce standby power consumption.

Embodiment 2.
FIG. 7 is a flow chart showing operation procedures of the hand dryer 1 according to the second embodiment. In the second embodiment, the hand dryer 1 completes charging of the bootstrap circuit 45 at the same time as the boost converter unit 30 completes boosting. In the second embodiment, the same reference numerals are assigned to the same components as in the first embodiment, and the configuration different from the first embodiment will be mainly described. Further, in Embodiment 2, the operation of the hand dryer 1 from when the power of the hand dryer 1 is turned on until the drive circuit 25 starts driving the DC brushless motor 21 will be described.

A delay period, which is a period from when the switching operation of the switching element 34 is turned on to when the switching element 44 is turned on, is set in the microcontroller 26 . The delay period is adjusted so that the end point of the period in which the bootstrap circuit 45 is charged coincides with the point in time when the boosting by the boosting converter section 30 is completed. Specifically, the delay period is determined based on the capacitance of the capacitor in the bootstrap circuit 45 and the time constant according to the limit resistance value.

When power is turned on to the hand dryer 1 by connecting it to the commercial AC power supply 23, the hand dryer 1 enters a standby state in step S20. In step S21, the hand dryer 1 determines whether or not a hand has been detected. If the hand is not detected (step S21, No), the hand dryer 1 repeats the procedure of step S21. When a hand is detected (step S21, Yes), the hand dryer 1 advances the procedure to step S22 and step S23.

In step S22, the microcontroller 26 turns on the switching element 41, so that the boost converter section 30 starts boosting. Simultaneously with turning on the switching element 41, the microcontroller 26 determines whether a preset delay period has elapsed in step S23. If the delay period has not elapsed (step S23, No), the hand dryer 1 repeats the procedure of step S23. If the delay period has passed (step S23, Yes), the microcontroller 26 turns on the switching element 44, and the hand dryer 1 starts charging the bootstrap circuit 45 in step S24. The charging of the bootstrap circuit 45 is performed during the boosting period.

In step S25, the hand dryer 1 determines whether or not boosting by the boosting converter section 30 has been completed. If boosting by the boosting converter unit 30 is not completed (step S25, No), step S25 is repeated. In step S26, the hand dryer 1 determines whether the charging of the bootstrap circuit 45 is completed. If charging of the bootstrap circuit 45 is not completed (step S26, No), step S26 is repeated.

By starting charging of bootstrap circuit 45 after the elapse of the delay period, boosting by boost converter section 30 and charging of bootstrap circuit 45 are completed at the same time. When the boosting by the boosting converter unit 30 is completed (step S25, Yes) and the charging of the bootstrap circuit 45 is completed (step S26, Yes), the drive circuit 25 starts operating in step S27. As described above, the hand dryer 1 starts driving the DC brushless motor 21 by the driving circuit 25 .

FIG. 8 is a timing chart for explaining the relationship between boosting and charging in the hand dryer 1 according to the second embodiment. FIG. 8 shows a "bus voltage" graph and a "charging voltage" graph for two cases. Case 2A is a case in which charging of the bootstrap circuit 45 is started when the bus voltage reaches a constant voltage value due to boosting. Case 2B is a case in which charging of the bootstrap circuit 45 is completed simultaneously with the completion of boosting by the boost converter section 30 .

In case 2A, the hand dryer 1 is powered on at time t11. After that, the hands are detected by the sensor 15, and the hand dryer 1 starts boosting by the boost converter section 30 at time t12. The drive circuit 25 starts driving the DC brushless motor 21 at time t13 when the charging of the bootstrap circuit 45 is completed.

In case 2B, as in case 2A, it is assumed that power is turned on to the hand dryer 1 at time t11, and boosting by the boost converter section 30 is started at time t12. In case 2B, the hand dryer 1 starts charging the bootstrap circuit 45 after the delay period has elapsed from time t12. At time t14, boosting and charging are completed at the same time. Drive circuit 25 starts driving DC brushless motor 21 at time t14.

In case 2B, driving of the DC brushless motor 21 can be started earlier than in case 2A by Δt2. Δt2 is the period from time t14 to time t13. Thus, the hand dryer 1 can start air blowing earlier in case 2B than in case 2A.

According to the second embodiment, the hand dryer 1 charges the bootstrap circuit 45 while boosting is being performed, and completes charging the bootstrap circuit 45 at the same time as the boosting by the boost converter section 30 is completed. As a result, the hand dryer 1 can shorten the time required to start air blowing. Moreover, the hand dryer 1 can reduce standby power consumption by not boosting the pressure in the standby state before the hand is detected. As described above, the hand dryer 1 can shorten the time required to start air blowing, and can reduce standby power consumption.

Furthermore, according to the second embodiment, the hand dryer 1 operates the driving circuit 25 at the same time that the charging of the bootstrap circuit 45 is completed. can be eliminated. Thereby, the hand dryer 1 can improve energy saving.

Embodiment 3.
FIG. 9 is a flow chart showing the operation procedure of the hand dryer 1 according to the third embodiment. In Embodiment 3, the hand dryer 1 stops charging the bootstrap circuit 45 after a set period of time has elapsed since the hand was no longer detected by the sensor 15 . In Embodiment 3, the operation of the hand dryer 1 after the drive circuit 25 finishes driving the DC brushless motor 21 until the hand dryer 1 returns to the standby state will be described. In the third embodiment, the same reference numerals are assigned to the same constituent elements as in the first or second embodiment, and the configuration different from that in the first or second embodiment will be mainly described. The operation of the hand dryer 1 according to the third embodiment may be performed after either the operation described in the first embodiment or the operation described in the second embodiment.

While the drive circuit 25 is driving the DC brushless motor 21, in step S30, the hand dryer 1 determines whether or not a hand has been detected. When a hand is detected (step S30, Yes), the hand dryer 1 repeats the procedure of step S30. If the hand is not detected (step S30, No), the drive circuit 25 stops operating in step S31. That is, the drive circuit 25 stops driving the DC brushless motor 21 .

In step S<b>32 , the hand dryer 1 turns off boosting by the boosting converter section 30 . Turning off boosting means that the microcontroller 26 stops boosting by switching the switching element 41 from on to off.

Next, in step S33, the hand dryer 1 determines whether or not a hand has been detected. If a hand is detected (step S33, Yes), the hand dryer 1 advances the procedure to step S34. If the hand is not detected (step S33, No), the hand dryer 1 advances the procedure to step S38.

In step S34, the microcontroller 26 switches the switching element 41 from off to on, thereby turning on boosting by the boost converter section 30. FIG. Turning on boosting means that the microcontroller 26 switches the switching element 41 from off to on to perform boosting.

In step S35, the hand dryer 1 determines whether or not boosting by the boosting converter section 30 has been completed. If boosting by the boosting converter unit 30 is not completed (step S35, No), step S35 is repeated. When the boost converter unit 30 completes boosting (step S35, Yes), the driving circuit 25 resumes its operation in step S36.

While the drive circuit 25 is driving the DC brushless motor 21, in step S37, the hand dryer 1 determines whether or not a hand has been detected. When a hand is detected (step S37, Yes), the hand dryer 1 repeats the procedure of step S37. If the hand is not detected (step S37, No), the hand dryer 1 returns to step S31.

At step S38, the microcontroller 26 determines whether the set period has elapsed. The set period is a period set in advance as a period from when the hand is no longer detected until charging of the bootstrap circuit 45 is stopped. An arbitrary value can be set in the microcontroller 26 to indicate the length of the set period. If the set period has not elapsed (step S38, No), the hand dryer 1 repeats the procedure of step S38.

If the set period has passed (step S38, Yes), the hand dryer 1 turns off charging of the bootstrap circuit 45 in step S39. Turning off the charging of the bootstrap circuit 45 means that the charging of the bootstrap circuit 45 is stopped by the microcontroller 26 switching the switching element 44 from on to off. After finishing the procedure of step S39, the hand dryer 1 is put into a standby state in step S40.

FIG. 10 is a timing chart for explaining the operation of the hand dryer 1 according to the third embodiment. The "boost" graph is a graph showing a period during which the boosting converter section 30 stops boosting as L (Low) level and a period during which boosting by the boosting converter section 30 is performed as H (High) level. . The "bus voltage" graph represents changes in bus voltage over time. The "charge" graph is a graph in which the period during which charging of the bootstrap circuit 45 is stopped is L level, and the period during which the bootstrap circuit 45 is being charged is represented as H level. The "charging voltage" graph represents changes in the charging voltage of the bootstrap circuit 45 on the time axis. The "hand detection" graph is a graph in which a period during which the hand is not detected by the sensor 15 is L level, and a period during which the hand is detected by the sensor 15 is H level.

FIG. 10 shows graphs of "boost", "bus voltage", "charging", "charging voltage" and "hand detection" in two cases. Case 3A is a case in which the boosting by the boosting converter unit 30 and the charging of the bootstrap circuit 45 are simultaneously turned off when the hand is no longer detected. Case 3B is a case in which boosting by the boost converter unit 30 is turned off when the hand is no longer detected, and charging of the bootstrap circuit 45 is turned off after a set time has elapsed since the hand was no longer detected. be.

In Case 3A, the boost is turned off when the hand is no longer detected, thereby causing the bus voltage to drop from the moment the hand is no longer detected. In addition, charging is turned off when the hand is no longer detected, so the charging voltage drops from the time when the hand is no longer detected. In Case 3A, it is assumed that a hand is detected while the bus voltage continues to drop. When the hand is detected, boosting by the boosting converter section 30 is turned on. That is, boosting is restarted. By resuming boosting, the bus voltage rises. Also, when a hand is detected, the charging of the bootstrap circuit 45 is turned on. That is, charging is restarted. By resuming charging, the charging voltage rises.

In Case 3A, it is assumed that the period from when charging is restarted to when charging is completed is longer than the period from when boosting is restarted to when boosting is completed. In this case, the time t21 at which charging is completed is later than the time at which boosting is completed. The drive circuit 25 starts driving the DC brushless motor 21 at time t21. The hand dryer 1 cannot start air blowing until charging is completed even if the pressure is increased.

On the other hand, in case 3B, charging of the bootstrap circuit 45 is continued for the set period Δt3 from when the hand is no longer detected. After Δt3 has elapsed, charging is switched off. Also in case 3B, it is assumed that a hand is detected while the bus voltage continues to drop. Boosting and charging resume when a hand is detected.

In case 3B, the charging stop is delayed by Δt3 compared to case 3A, so the amount of decrease in charging voltage when a hand is detected is smaller than in case 3A. Therefore, the hand dryer 1 can shorten the period from when the hand is detected to when the charging is completed, compared to the case 3A. In case 3B, charging is completed at time t22 earlier than time t21 in case 3A. In the case 3B, the hand dryer 1 can start driving the DC brushless motor 21 earlier by Δt4 than in the case 3A. Δt4 is the period from time t22 to time t21. The hand dryer 1 can start air blowing earlier in case 3B than in case 3A. The hand dryer 1 can solve the problem that air blowing cannot be started until charging is completed even if the pressure is completed.

According to the third embodiment, the hand dryer 1 stops charging the bootstrap circuit 45 after a set period has elapsed since the hand was no longer detected by the sensor 15, so that when the hand is detected again. It is possible to shorten the time required to start air blowing in. Moreover, the hand dryer 1 can reduce standby power consumption by not boosting the pressure in the standby state before the hand is detected. As described above, the hand dryer 1 can shorten the time required to start air blowing, and can reduce standby power consumption. Moreover, the hand dryer 1 can improve energy saving by stopping the charging of the bootstrap circuit 45 .

Embodiment 4.
FIG. 11 is a flow chart showing operation procedures of the hand dryer 1 according to the fourth embodiment. In the fourth embodiment, hand drying apparatus 1 stops boosting by boost converter section 30 after a set period has elapsed since sensor 15 no longer detects the hand. In the fourth embodiment, the operation of the hand dryer 1 after the drive circuit 25 finishes driving the DC brushless motor 21 until the hand dryer 1 returns to the standby state will be described. In the fourth embodiment, the same reference numerals are assigned to the same components as in the first to third embodiments, and the configuration different from the first to third embodiments will be mainly described. The operation of the hand dryer 1 according to the fourth embodiment may be performed after either the operation described in the first embodiment or the operation described in the second embodiment.

While the drive circuit 25 is driving the DC brushless motor 21, in step S50, the hand dryer 1 determines whether or not a hand has been detected. When a hand is detected (step S50, Yes), the hand dryer 1 repeats the procedure of step S50. If the hand is not detected (step S50, No), the drive circuit 25 stops operating in step S51. That is, the drive circuit 25 stops driving the DC brushless motor 21 . In step S<b>52 , the hand dryer 1 turns off charging of the bootstrap circuit 45 .

Next, in step S53, the hand dryer 1 determines whether or not a hand has been detected. If a hand is detected (step S53, Yes), the hand dryer 1 advances the procedure to step S54. If the hand is not detected (step S53, No), the hand dryer 1 advances the procedure to step S58.

In step S<b>54 , the hand dryer 1 turns on charging of the bootstrap circuit 45 . Turning on charging refers to charging of the bootstrap circuit 45 by the microcontroller 26 switching the switching element 44 from off to on.

In step S55, the hand dryer 1 determines whether charging of the bootstrap circuit 45 is completed. If charging of the bootstrap circuit 45 is not completed (step S55, No), step S55 is repeated. When the charging of the bootstrap circuit 45 is completed (step S55, Yes), the driving circuit 25 resumes its operation in step S56.

While the drive circuit 25 is driving the DC brushless motor 21, in step S57, the hand dryer 1 determines whether or not a hand has been detected. If a hand is detected (step S57, Yes), the hand dryer 1 repeats the procedure of step S57. If the hand is not detected (step S57, No), the hand dryer 1 returns to step S51.

At step S58, the microcontroller 26 determines whether the set period has elapsed. The set period is a period that is set in advance as a period from when the hand is no longer detected to when boost converter section 30 stops boosting. An arbitrary value can be set in the microcontroller 26 to indicate the length of the set period. If the set period has not elapsed (step S58, No), the hand dryer 1 repeats the procedure of step S58.

When the set period has passed (step S58, Yes), the hand dryer 1 turns off the boosting by the boost converter section 30 in step S59. After completing the procedure of step S59, the hand dryer 1 is put into a standby state in step S60.

FIG. 12 is a timing chart for explaining the operation of the hand dryer 1 according to the fourth embodiment. FIG. 12 shows graphs of "boost", "bus voltage", "charging", "charging voltage" and "hand detection" in two cases. Case 4A is a case in which the boosting by the boosting converter unit 30 and the charging of the bootstrap circuit 45 are simultaneously turned off when the hand is no longer detected. Case 4B is a case in which charging of the bootstrap circuit 45 is turned off when the hand is no longer detected, and boosting by the boost converter section 30 is turned off after a set time has elapsed since the hand is no longer detected. be.

In case 4A, the boost is turned off when the hand is no longer detected, thereby reducing the bus voltage from the moment the hand is no longer detected. In addition, charging is turned off when the hand is no longer detected, so the charging voltage drops from the time when the hand is no longer detected. In Case 4A, it is assumed that a hand is detected while the bus voltage continues to drop. When the hand is detected, boosting by the boosting converter section 30 is turned on. That is, boosting is restarted. By resuming boosting, the bus voltage rises. Also, when a hand is detected, the charging of the bootstrap circuit 45 is turned on. That is, charging is restarted. By resuming charging, the charging voltage rises.

In Case 4A, it is assumed that the period from the resumption of boosting to the completion of boosting is longer than the period from the resumption of charging to the completion of charging. In this case, the time t31 at which boosting is completed is later than the time at which charging is completed. The drive circuit 25 starts driving the DC brushless motor 21 at time t31. Even if charging is completed, the hand dryer 1 cannot start blowing air until boosting is completed.

On the other hand, in case 4B, boosting by the boosting converter unit 30 is continued for the set period Δt5 from when the hand is no longer detected. After Δt5 has elapsed, the boost is turned off. Also in case 4B, it is assumed that a hand is detected while the bus voltage continues to drop. Boosting and charging resume when a hand is detected.

In case 4B, the stoppage of boosting is delayed by Δt5 compared to case 4A, so the drop in bus voltage when a hand is detected is smaller than in case 4A. Therefore, the hand dryer 1 can shorten the period from when the hand is detected to when the pressure rise is completed, compared to the case 4A. In case 4B, charging is completed at time t32 earlier than time t31 in case 4A. In the case 4B, the hand dryer 1 can start driving the DC brushless motor 21 earlier by Δt6 than in the case 4A. Δt6 is the period from time t32 to time t31. Thus, the hand dryer 1 can start air blowing earlier in case 4B than in case 4A. The hand dryer 1 can solve the problem that air blowing cannot be started until the pressure rise is completed even if charging is completed.

According to the fourth embodiment, hand dryer 1 stops boosting by boost converter unit 30 after a set period has passed since sensor 15 no longer detects the hand, so that when the hand is detected again, It is possible to shorten the time required to start air blowing in. Moreover, the hand dryer 1 can reduce standby power consumption by not boosting the pressure in the standby state before the hand is detected. As described above, the hand dryer 1 can shorten the time required to start air blowing, and can reduce standby power consumption. Moreover, the hand dryer 1 can improve energy saving by stopping the charging of the bootstrap circuit 45 .

Embodiment 5.
FIG. 13 is a flow chart showing the operating procedure of the hand dryer 1 according to the fifth embodiment. In the fifth embodiment, hand drying apparatus 1 stops boosting by boost converter section 30 and charging of bootstrap circuit 45 when hand is no longer detected by sensor 15 . In the fifth embodiment, the operation of the hand dryer 1 after the drive circuit 25 finishes driving the DC brushless motor 21 until the hand dryer 1 returns to the standby state will be described. In Embodiment 5, the same components as those in Embodiments 1 to 4 are denoted by the same reference numerals, and configurations different from those in Embodiments 1 to 4 will be mainly described. The operation of the hand dryer 1 according to the fifth embodiment may be performed after either the operation described in the first embodiment or the operation described in the second embodiment.

While the drive circuit 25 is driving the DC brushless motor 21, in step S70, the hand dryer 1 determines whether or not a hand has been detected. When a hand is detected (step S70, Yes), the hand dryer 1 repeats the procedure of step S70. If the hand is not detected (step S70, No), the drive circuit 25 stops operating in step S71. That is, the drive circuit 25 stops driving the DC brushless motor 21 . After finishing the procedure of step S71, the hand dryer 1 advances the procedure to step S72 and step S73.

In step S<b>72 , the hand dryer 1 turns off boosting by the boosting converter section 30 . Also, in step S73, the hand dryer 1 turns off the charging of the bootstrap circuit 45. FIG. As a result, the hand dryer 1 turns off the boosting by the boosting converter section 30 and the charging of the bootstrap circuit 45 at the same time. After completing the procedure of step S72 and the procedure of step S73, the hand dryer 1 enters a standby state in step S74.

According to the fifth embodiment, hand dryer 1 stops boosting by boost converter section 30 and stops charging of bootstrap circuit 45 when hand is no longer detected by sensor 15 . Thereby, the hand dryer 1 can obtain high energy saving.

The configuration shown in each of the above embodiments is an example of the contents of the present disclosure. The configuration of each embodiment can be combined with another known technique. Configurations of respective embodiments may be combined as appropriate. A part of the configuration of each embodiment can be omitted or changed without departing from the gist of the present disclosure.

1 hand dryer, 2 hand insertion part, 3 housing, 4 front part, 5 back part, 6 water receiving part, 7 drain tank, 10 blower, 11, 12 nozzle, 13, 14, 17 duct, 15 sensor, 16 Intake port 18 Air filter 20 Control unit 21 DC brushless motor 22 Turbo fan 23 Commercial AC power supply 24 Power supply unit 25 Drive circuit 26 Microcontroller 30 Boost converter unit 31 Rectifier circuit 32, 36 Piezoresistor 33 Inductor 34,41,44 Switching element 35 Fast recovery diode 37 Smoothing capacitor 38 Control power supply circuit 39 Resistor 40 Switching control IC 42, 43 DC bus 45 Bootstrap circuit.

Claims (6)

a housing having a hand insertion portion;
a blowing unit for sending out an airflow to be jetted by the hand insertion unit;
a hand detection unit that detects a hand inserted into the hand insertion unit;
a power supply unit including a booster circuit for boosting a DC voltage;
a drive circuit that receives power supply from the power supply unit and drives the blower unit;
a bootstrap circuit connected to the drive circuit;
The drive circuit is capable of driving the blower unit through charging of the bootstrap circuit,
The booster circuit starts boosting when the hand is detected by the hand detection unit,
The hand dryer, wherein charging of the bootstrap circuit is performed while the voltage is boosted. 2. The hand dryer according to claim 1, wherein charging of said bootstrap circuit is started at the same time said boosting is started. 2. The hand dryer according to claim 1, wherein charging of said bootstrap circuit is completed upon completion of said boosting. The booster circuit stops boosting when the hand detection unit no longer detects a hand after the drive circuit starts driving the blower unit,
4. The charging of the bootstrap circuit according to any one of claims 1 to 3, wherein the charging of the bootstrap circuit is stopped after a preset period has passed since the hand is no longer detected by the hand detection unit. hand drying equipment. charging of the bootstrap circuit is stopped when the hand detection unit no longer detects the hand after the drive circuit starts driving the blower unit;
4. The booster circuit according to any one of claims 1 to 3, wherein the booster circuit stops boosting after a preset period has elapsed since the hand was no longer detected by the hand detector. Hand dryer. After the driving circuit starts driving the air blowing unit, when the hand detection unit no longer detects the hand, the boosting circuit stops the boosting and the charging of the bootstrap circuit is stopped. 4. A hand dryer according to any one of claims 1 to 3, characterized in that:

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