[0001] The present invention relates to a dryer circuit according to the pre-characterizing
clause of claim 1, 9 or 13.
[0002] The conventional dryer is operable only after establishing connection with an AC
power plug through a power cord. The use of the dryer is then limited by the length
of the cord to the area that can be reached by the cord from the AC power receptacle.
Therefore, it is very inconvenient for traveling purposes, in particular, when traveling
in countries where the AC power specifications, such as voltages, cycles, and receptacles
vary from one to another. Different converters and transformers are needed if the
user wants to use a conventional dryer. Furthermore, since the conventional AC-powered
dryers are powered by AC currents with sinusoidal amplitudes, most use a diode to
control the generation of heat. When the switch is shifted to a low heat setting,
the one-way conduction property of the diode filters out a half cycle of the AC current
that passes through the heating filament. When the switch is shifted to a high heat
setting, the current to the heating filament does not go through the diode so that
heat can be generated at full output. At the same time, in order to provide a DC current
to the motor, an additional bridge rectifier has to be employed to supply the needed
DC power.
[0003] This in mind, the present invention aims at providing a dryer circuit to control
the power consumed by the motor and the power consumed by the heating units at the
same time for generating airflow at the desired heat output.
[0004] This is achieved by a dryer circuit according to claim 1, 9 or 13. The dependent
claims pertain to corresponding further developments and improvements.
[0005] As will be seen more clearly from the detailed description following below, the claimed
dryer circuit includes a connection controller coupled to a power unit, a first heating
unit, and a second heating unit, for switching coupling between the first heating
unit, the power unit, and the second heating unit.
[0006] In the following, the invention is further illustrated by way of example, taking
reference to the accompanying drawings. Thereof
FIG. 1 is a diagram illustrating the dryer circuit according to a first embodiment
of the present invention,
FIG. 2 is a diagram illustrating the dryer circuit of FIG.1 operating in the mode
1,
FIG. 3 shows the calculation of the power consumptions on the components in the dryer
circuit in the mode 1,
FIG. 4 is a diagram illustrating the dryer circuit of FIG.1 operating in the mode
2,
FIG. 5 shows the calculation of the power consumptions on the components in the dryer
circuit in the mode 2,
FIG. 6 is a diagram illustrating the dryer circuit of FIG.1 operating in the mode
3,
FIG. 7 shows the calculation of the power consumptions on the components in the dryer
circuit in the mode 3,
FIG. 8 is a diagram illustrating a first connection controller of the first embodiment
of the present invention,
FIG. 9 is a diagram illustrating a second connection controller of the first embodiment
of the present invention,
FIG. 10 is a diagram illustrating the connection controller of FIG. 9 in the mode
1,
FIG. 11 is a diagram illustrating the connection controller of FIG. 9 in the mode
2,
FIG. 12 is a diagram illustrating the connection controller of FIG. 9 in the mode
3,
FIG. 13 is a diagram illustrating a third connection controller of the first embodiment
of the present invention,
FIG. 14 is a diagram illustrating a fourth connection controller of the first embodiment
of the present invention,
FIG. 15 is a diagram illustrating a fifth connection controller of the first embodiment
of the present invention,
FIG. 16 is a diagram illustrating an equivalent dryer circuit according to the first
embodiment of the present invention,
FIG. 17 is a diagram illustrating the dryer circuit according to a second embodiment
of the present invention,
FIG. 18 is a diagram illustrating the dryer circuit of FIG. 17 operating in the mode
1,
FIG. 19 is a diagram illustrating the dryer circuit of FIG.17 operating in the mode
3,
FIG. 20 is a diagram illustrating a first connection controller of the second embodiment
of the present invention,
FIG. 21 is a diagram illustrating a second connection controller of the second embodiment
of the present invention,
FIG. 22 is a diagram illustrating the connection controller of FIG. 21 in the mode
1,
FIG. 23 is a diagram illustrating the connection controller of FIG. 21 in the mode
3,
FIG. 24 is a diagram illustrating a third connection controller of the second embodiment
of the present invention,
FIG. 25 is a diagram illustrating a fourth connection controller of the second embodiment
of the present invention,
FIG. 26 is a diagram illustrating a fifth connection controller of the second embodiment
of the present invention,
FIG. 27 is a diagram illustrating a sixth connection controller of the second embodiment
of the present invention,
FIG. 28 is a diagram illustrating a seventh connection controller of the second embodiment
of the present invention,
FIG. 29 is a diagram illustrating the dryer circuit according to a third embodiment
of the present invention,
FIG. 30 is a diagram illustrating a first connection controller of the third embodiment
of the present invention,
FIG. 31 is a diagram illustrating a second connection controller of the third embodiment
of the present invention,
FIG. 32 is a diagram illustrating a third connection controller of the third embodiment
of the present invention,
FIG. 33 is a diagram illustrating a fourth connection controller of the third embodiment
of the present invention,
FIG. 34 is a diagram illustrating a fifth connection controller of the third embodiment
of the present invention,
FIG. 35 is a diagram illustrating alternative embodiment of the second embodiment
of the present invention,
FIG. 36 is a diagram illustrating a dryer circuit capable of operating in mode 2 according
to the third embodiment of the present invention, and
FIG. 37 shows the calculation of the power consumptions on the components in the main
circuit in mode 2.
[0007] The present invention utilizes a portable electrical power source (e.g., battery).
Therefore, the portable dryer circuit of the present invention does not need to connect
to an AC receptacle.
[0008] Please refer to FIG. 1 . FIG. 1 is a diagram illustrating the dryer circuit 100 according
to a first embodiment of the present invention. As shown in FIG.1, the dryer circuit
100 comprises a main circuit 110 and a connection controller 120. The main circuit
110 comprises a power unit B, a motor M (including a fan), two diodes D
1 and D
2, two heating units HG
1 and HG
2, a resistor R
1, and four nodes N
1, N
2, N
3, and N
4. However, the node N
2 is equivalent to the node N
4 electrically. The power unit B comprises a positive end for providing a voltage V
B (20 volts), and a negative end for serving as a ground end (0 volt). The heating
units HG
1 and HG
2 generate heat according to power consumed by the heating units HG
1 and HG
2, respectively. The motor M (including a fan) generates airflow with a volume according
to the power consumed by the motor M.
[0009] Between the positive end of the power unit B and node N
1, the heating unit HG
1, the motor M, the diode D
2, and the resistor R
1 form a circuit group G
1. In the circuit group G
1, the motor M is coupled to the diode D
2 and the resistor R
1, which the diode D
2 and the resistor R
1 are coupled in series, and the motor is further coupled to the heating unit HG
1 in parallel.
[0010] Between the positive end of the power unit B and node N
3, the heating unit HG
2, the motor M, and the diode D
1, form a circuit group G
2. In the circuit group G
2, the motor M and the diode D
1 are coupled in series, and the motor M is further coupled to the heating unit HG
2 in parallel.
[0011] The connection controller 120 controls the connection between the nodes N
1 and N
2 and the connection between the nodes N
3 and N
4, respectively. Therefore, by controlling the current to flow through the circuit
groups G
1, the circuit group G
2, or both the circuit groups G
1 and G
2, different modes of the dryer circuit 100 are achieved.
[0012] The following are to define four operating modes, mode 0, 1, 2, and 3 of the present
invention. In mode 0, the connection controller 120 disconnects both the nodes N
1 from N
2 and the nodes N
3 from N
4. Therefore, no current flows through the motor M, the heating units HG
1 and HG
2. In mode 1, the connection controller 120 connects the node N
1 to the node N
2, which means current only flows through the circuit group G
1. In mode 2, the connection controller 120 connects the node N
3 to the node N
4, which means current only flows through the circuit group G
2. In mode 3, the connection controller 120 connects the node N
1 to the node N
2, and connects the node N
3 to the node N
4, which means current flows through both the circuit group G
1 and circuit group G
2.
[0013] Please refer to FIG. 2. FIG. 2 is a diagram illustrating the dryer circuit 100 operating
in mode 1. As shown in FIG. 2, the connection controller 120 connects the node N
1 to the node N
2, but disconnects the node N
3 from the node N
4. The diode D
1, instead of filtering a half cycle of the AC current as utilized in a traditional
hair dryer, blocks the DC current flowing through the heating unit HG
2 in mode 1 operation. Therefore, the electric power provided by the power unit B passes
through the circuit group G
1, and the voltage on the heating unit HG
1 equals to the voltage V
B. Neglecting the small voltage drops over the diode D
2, the voltage V
B is shared by the resistor R
1 and the motor M according to their impedances respectively.
[0014] In mode 1, the power consumed respectively by the heating unit HG
1 and the motor M are calculated by the following equations:

wherein V
M represents the voltage on the motor M, P
HG1 and P
M represent the power consumed by the heating unit HG
1 and the motor M respectively, and R
HG1 , R
1 and R
M represent the impedance of the heating unit HG
1, resistor R
1 and the motor M respectively.
[0015] Please refer to FIG. 3. FIG. 3 shows the calculation of the power consumptions on
the components in the main circuit 110 in mode 1. As shown in FIG. 3, the power to
the motor M is 25.9 Watt, and the total power of the main circuit 1 10 is 236.3 Watt.
[0016] Please refer to FIG. 4. FIG. 4 is a diagram illustrating the dryer circuit 100 operating
in mode 2. As shown in FIG. 4, the connection controller 120 connects the node N
3 to the node N
4, but disconnects the node N
1 from the node N
2. The diode D
2 blocks the DC current flowing through the heating unit HG
1 in mode 2 operation. Therefore, the electric power provided by the power unit B passes
through the circuit group G
2, and the voltage on the heating unit HG
2 equals to the voltage V
B. Neglecting the small voltage drops over the diode D
1, the voltage on the motor M equals to the voltage V
B.
[0017] In mode 2, the power consumed respectively by the heating unit HG
2 and the motor M are calculated by the following equations:

wherein the P
HC2 represents the power consumed by the heat unit HG
2, and R
HG2 represents the impedance of the heat unit HG
2.
[0018] Please refer to FIG. 5. FIG. 5 shows the calculation of the power consumptions on
the components in the main circuit 110 in mode 2. As shown in FIG. 5, the power to
the motor M is 50 Watt and the total power of the main circuit 110 is 250 Watt. The
total power of the main circuit 110 has slight difference between in mode 2 and mode
1. However, the power to the motor M in mode 2 is almost twice as much as that in
mode 1.
[0019] Please refer to FIG. 6. FIG. 6 is a diagram illustrating the dryer circuit 100 operating
in mode 3. As shown in FIG. 6, the connection controller 120 connects the node N
1 to the node N
2, and connects the node N
3 to the node N
4. Therefore, the electric power provided by the power unit B passes through both the
circuit group G
1 and circuit group G
2, and the voltage on the heating unit HG
1 equals to the voltage V
B and the voltage on the heating unit HG
2 equals to the voltage V
B. Because the resistor R
1 is disposed in the circuit group G
1, the current flowing through the resistor R
1 and the diode D
2 can be ignored in mode 3. Neglecting the small voltage drops over the diode D
1, the voltage on the motor M equals to the voltage V
B.
[0020] In mode 3, the power consumed respectively by the heating units HG
1 and HG
2 and the motor M are calculated by the following equations:

wherein the P
HG1 and P
HG2 respectively represent the power consumed by the heat units HG
1 and HG
2, R
HG1 and R
HG2 respectively represent the impedances of the heat units HG
1 and HG
2, P
M represents the power consumed by the motor M, and R
M represents the impedance of the motor M.
[0021] Please refer to FIG. 7. FIG. 7 shows the calculation of the power consumptions on
the components in the main circuit 110 in mode 3. As shown in FIG. 7, the power to
the motor M is 50 Watt, and the total power of the main circuit 110 is 450 Watt. Both
the power to the motor M and the total power of the main circuit 110 in mode 3 are
nearly twice as much as those in mode 1.
[0022] Please refer to FIG. 8. FIG. 8 is a diagram illustrating a first connection controller
800 of the first embodiment of the present invention. As shown in FIG. 8, the connection
controller 800 comprises two switches SW
1 and SW
2 respectively for controlling the connection between nodes N
1 and N
2 and the connection between nodes N
3 and N
4. The switches SW
1 and SW
2 are respectively controlled to achieve the operation of the dryer circuit 100 in
modes 0, 1, 2, and 3. The switches SW
1 and SW
2 can be mechanical switches.
[0023] Please refer to FIG. 9. FIG. 9 is a diagram illustrating the connection controller
801 based on the connection controller 800 and utilizing a slide switch SWT of the
present invention. As shown in FIG. 9, the slide switch SWT comprises a base H, a
slide button T, and two conducting pads P
1 and P
2. The slide switch SWT is disposed for controlling the connection between the nodes
N
1 and N
2 and the connection between the nodes N
3 and N
4. The conducting pads P
3 and P
4 are disposed for the nodes N
1 and N
2 and are both shaped as dots. The conducting pads P
5 and P
6 are disposed for the nodes N
3 and N
4 and are shaped as lines. By moving the slide button T of the slide switch SWT to
different positions, the dryer circuit 100 can operate in modes 0, 1, 2, and 3.
[0024] In FIG. 9, by default setting, the connection controller 801 achieves mode 0 for
the dryer circuit 100 by disposing the slide button T in a position so that both the
conducting pads P
1 and P
2 do not contact with the pads P
3, P
4, P
5, and P
6.
[0025] Please refer to FIG. 10. FIG. 10 is a diagram illustrating the connection controller
801 in mode 1. As shown in FIG. 10, the slide button T moves downward so that the
conducting pad P
2 contacts with the conducting pads P
3 and P
4 in order to establish the connection between the nodes N
1 and N
2. Therefore, the nodes N
1 and N
2 are short-circuited by the conducting pad P
2, and consequently the dryer circuit 100 operates in mode 1.
[0026] Please refer to FIG. 11. FIG. 11 is a diagram illustrating the connection controller
801 in mode 2. As shown in FIG. 11, the slide button T moves further downward so that
the conducting pad P
2 shifts away from pads P
3 and P
4 and contacts with the conducting pads P
5 and P
6 to establish the connection between the nodes N
3 and N
4. Therefore, the nodes N
3 and N
4 are short-circuited by the conducting pad P
2, and consequently the dryer circuit 100 operates in mode 2.
[0027] Please refer to FIG. 12. FIG. 12 is a diagram illustrating the connection controller
801 in mode 3. As shown in FIG. 12, the slide button T moves further downward so that
the conducting pad P
2 still contacts with the conducting pads P
5 and P
6 in order to establish the connection between the nodes N
3 and N
4, and the conducting pad P
1 contacts with the conducting pads P
3 and P
4 in order to establish the connection between the nodes N
1 and N
2, Therefore, the nodes N
1 and N
2 are short-circuited by the conducting pad P
1, the nodes N
3 and N
4 are short-circuited by the conducting pad P
2, and consequently the dryer circuit 100 operates in mode 3.
[0028] Please refer to FIG. 13. FIG. 13 is a diagram illustrating another connection controller
1300 of the first embodiment of the present invention. As shown in FIG. 13, the connection
controller 1300 comprises a transistor Q
1 controlled by a switch SW
3 for the connection between the nodes N
1 and N
2, and a transistor Q
2 controlled by a switch SW
4 for the connection between the nodes N
3 and N
4. The transistor Q
1 connects the node N
1 to node N
2 when the switch SW
3 is short-circuited to the power unit B for transmitting the voltage V
B so that the control end of the transistor Q
1 receives the voltage V
B from the power unit B. The transistor Q
1 disconnects the node N
1 from the node N
2 when the switch SW
3 is open (no voltage is received on the control end of the transistor Q
1). The transistor Q
2 connects the node N
3 to the node N
4 when the switch SW
4 is short-circuited to the power unit B for transmitting the voltage V
B so that the control end of the transistor Q
2 receives the voltage V
B from the power unit B. The transistor Q
2 disconnects the node N
3 from the node N
4 when the switch SW
4 is open (no voltage is received on the control end of the transistor Q
2). Additionally, the voltage transmitted to the control ends of the transistors Q
1 and Q
2 for controlling the transistors Q
1 and Q
2 can be positive or negative, depending on the transistors being forward-biased or
reverse-biased. The switches SW
3 and SW
4 are respectively controlled to achieve the operation of the dryer circuit 100 in
modes 0, 1, 2, and 3.
[0029] Please refer to FIG. 14. FIG. 14 is a diagram illustrating the connection controller
1301 based on the connection controller 1300 and utilizing a slide switch SWT of the
present invention. As shown in FIG. 14, the slide switch SWT is disposed for controlling
the connection between the nodes N
1 and N
2 and the connection between the nodes N
3 and N
4. The dryer circuit 100 operates in modes 0, 1, 2, and 3 according to the movement
of the slide button T of the slide switch SWT as described from FIG. 9 to FIG. 12
and the related description is omitted.
[0030] Please refer to FIG. 15. FIG. 15 is a diagram illustrating another connection controller
1 500 of the first embodiment of the present invention. As shown in FIG. 15, the connection
controller 1 500 comprises two transistors Q
1 and Q
2 both controlled by a slide switch SWT, three pads P
6, P
8 and P
10 connected to the power unit B, a pad P
5 connected to the control end of transistor Q
1, a pad P
7 connected to the control end of transistor Q
2, and a pad P
9 connected to both the control ends of transistor Q
1 and transistor Q
2 through the diodes D
3 and D
4 respectively. The slide switch SWT comprises a base H, a slide button T, and a conducting
pad P
1.
[0031] When the slide button T of the slide switch SWT shifts to the position for mode 1,
the pad P
5 and the pad P
6 are short-circuited by the conducting pad P
1, so the control end of the transistor Q
1 receives the voltage V
B from the power unit B. Therefore, the transistor Q
1 connects the node N
1 to the node N
2. The diode D
3 prevents the transistor Q
2 from receiving the voltage V
B from the power unit B when the pad P
5 and the pad P
6 are short-circuited.
[0032] When the slide button T of the slide switch SWT shifts to the position for mode 2,
the pad P
7 and the pad P
8 are short-circuited by the conducting pad P
1, so the control end of the transistor Q
2 receives the voltage V
B from the power unit B. Therefore, the transistor Q
2 connects the node N
3 to the node N
4. The diode D
4 prevents the transistor Q
1 from receiving the voltage V
B from the power unit B when the pad P
7 and the pad P
8 are short-circuited.
[0033] When the slide button T of slide switch SWT shifts to the position for mode 3, the
pad P
9 and the pad P
10 are short-circuited by the conducting pad P
1, so both the control ends of the transistors Q
1 and Q
2 receive the voltage V
B from the power unit B. Therefore, the transistor Q
1 connects the node N
1 to the node N
2 and the transistor Q
2 connects the node N
3 to the node N
4.
[0034] In summary, the dryer circuit 100 can operate in modes 0, 1 , 2, and 3 by shifting
the slide button T of the slide switch SWT to different positions.
[0035] Please refer to FIG. 16. FIG. 16 is a diagram illustrating another dryer circuit
1600 which is electrically equivalent to the dryer circuit 100 of the first embodiment
of the present invention. As shown in FIG. 16, the dryer circuit 1600 comprises a
main circuit 1610 and a connection controller 1620. The main circuit 1610 comprises
a power unit B, a motor M (including a fan), two diodes D
1 and D
2, two heating units HG
1 and HG
2, a resistor R
1, and three nodes N
1, N
2, and N
4.
[0036] Between the node N
2 and the negative end of the power unit B, the heating unit HG
1, the motor M, the diode D
2, and the resistor R
1 form a circuit group G
1. Between the node N
4 and the negative end of the power unit B, the heating unit HG
2, the motor M, and the diode D
1, form a circuit group G
2.
[0037] The connection controller 1620 controls the connection between the nodes N
1 and N
2, and the connection between the nodes N
1 and N
4, respectively. Therefore, by controlling the current to flow through the circuit
groups G
1, the circuit group G
2, or both the circuit groups G
1 and G
2, different modes of the dryer circuit 100 are achieved.
[0038] Utilizing the connection controller 1620, the main circuit 1610 can operate in mode
0, 1, 2 and 3. Though the dispositions of all components of the dryer circuit 1600
are rearranged and different from those of the dryer circuit 100, the dryer circuit
1600 is electrically equivalent to the dryer circuit 100.
[0039] Please refer to FIG. 17. FIG. 17 is a diagram illustrating a second embodiment of
the present invention. As shown in FIG.17, the dryer circuit 1700 comprises a main
circuit 1710 and a connection controller 1 720. The main circuit 1 710 comprises a
power unit B, a motor M (including a fan), a diode D
1, two heating units HG
1 and HG
2, a resistor R
1, and four nodes N
1, N
2, N
3, and N
4. The power unit B provides a voltage V
B. The heating units HG
1 and HG
2 generate heat according to power consumed by the heating units HG
1 and HG
2 respectively. The motor M (including a fan) generates airflow with a volume according
to the power consumed by the motor M.
[0040] Between the node N
2 and the negative end of the power unit B, the heating unit HG
1, the motor M, and the resistor R
1 form a circuit group G
3. In the circuit group G
3, the motor M and the resistor R
1 are coupled in series, and the motor M and the heating unit HG
1 are coupled in parallel.
[0041] Between the nodes N
2 and N
3, the heating unit HG
2, the motor M, and the diode D
1, form a circuit group G
4. In the circuit group G
4, the motor M and the diode D
1 are coupled in series, and the motor M and the heating unit HG
2 are coupled in parallel.
[0042] The connection controller 1 720 controls the connection between the nodes N
1 and N
2, and the connection between the nodes N
3 and N
4, respectively. Therefore, by controlling the current to flow through the circuit
groups G
3, or both the circuit groups G
3 and G
4, different modes of the dryer circuit 1700 are achieved.
[0043] When the dryer circuit 1700 operates in mode 0, the main circuit 1710 is turned off.
The connection controller 1 720 disconnects the connection between the nodes N
1 and N
2. Therefore, no current flows through the motor M, the heating units HG
1 and HG
2.
[0044] However, when the connection controller 1720 disconnects the node N
1 from the node N
2 and connects the node N
3 to the node N
4, no current flows through the circuit group G
4. Therefore, the dryer circuit 1700 does not operate in mode 2 in the second embodiment
of the present invention.
[0045] Please refer to FIG. 18. FIG. 18 is a diagram illustrating the dryer circuit 1700
operating in mode 1. As shown in FIG. 18, the connection controller 1720 connects
the node N
1 to the node N
2, but disconnects the node N
3 from the node N
4. The diode D
1 blocks the DC current flowing through the heating unit HG
2 in mode 1 operation. Therefore, the electric power provided by the power unit B only
passes through the circuit group G
3, the voltage on the heating unit HG
1 equals to the voltage V
B, and the resistor R
1 and the motor M share the voltage V
B according to their impedances respectively.
[0046] In the mode 1, the power consumed respectively by the heating unit HG
1 and the motor M are calculated by the following equations:

wherein V
M represents the voltage on the motor M, P
HG1 and P
M represent the power consumed by the heating unit HG
1 and the motor M respectively, and R
HG1, R
1 and R
M represent the impedance of the heating unit HG
1, resistor R
1 and the motor M respectively. The calculation of the power consumptions on the components
in the main circuit 1 710 in mode 1 is similar to FIG. 3 and is omitted.
[0047] Please refer to FIG. 19. FIG. 19 is a diagram illustrating the dryer circuit 1700
operating in mode 3. As shown in FIG. 19, the connection controller 1 720 connects
the node N
1 to the node N
2, and connects the node N
3 to the node N
4. Therefore, the electric power provided by the power unit B passes through both the
circuit group G
3 and G
4. Because the resistor R
1 is disposed in the circuit group G
3, the current flowing through the resistor R
1 can be ignored in mode 3. Neglecting the small voltage drops over the diode D
1, the voltage on the motor M equals to the voltage V
B.
[0048] In mode 3, the power consumed respectively by the heating units HG
1 and HG
2 and the motor M are calculated by the following equations:

wherein the P
HG1 and P
HG2 respectively represent the power consumed by the heat units HG
1 and HG
2, and R
HG1 and R
HG2 respectively represent the equivalent impedances of the heat units HG
1 and HG
2. The calculation of the power consumptions on the components in the main circuit
1710 in mode 3 is similar to FIG. 7 and is omitted.
[0049] Please refer to FIG. 20. FIG. 20 is a diagram illustrating a first connection controller
2000 of the second embodiment of the present invention. As shown in FIG. 20, the connection
controller 2000 comprises two switches SW
1 and SW
2 respectively for the connection between the nodes N
1 and N
2 and the connection between the nodes N
3 and N
4. The switches SW
1 and SW
2 are respectively controlled to achieve the operation of the dryer circuit 1700 in
modes 0, 1 and 3. In the connection controller 2000, the switches SW
1 and SW
2 can be mechanical switches.
[0050] Please refer to FIG. 21. FIG. 21 is a diagram illustrating the connection controller
2001 based on the connection controller 2000 and utilizing a slide switch SWT of the
present invention. As shown in FIG. 21, the slide switch SWT comprises a base H, a
slide button T and two conducting pads P
1 and P
2. The slide switch SWT is disposed for controlling the connection between the nodes
N
1 and N
2 and the connection between the nodes N
3 and N
4. The conducting pads P
3 and P
4 are disposed for the nodes N
1 and N
2, and the conducting pads P
5 and P
6 are disposed for the nodes N
3 and N
4. The dryer circuit 1700 operates in modes 0, 1 and 3 according to the movement of
the slide button T of the slide switch SWT.
[0051] In FIG. 21, by default setting, the connection controller 2001 achieves mode 0 operation
for the dryer circuit 1 700 by disposing the slide button T in a position that both
the conducting pads P
1 and P
2 do not contact with the pads P
3, P
4, P
5, and P
6.
[0052] Please refer to FIG. 22. FIG. 22 is a diagram illustrating the connection controller
2001 in mode 1. As shown in FIG. 22, the slide button T moves downward so that the
conducting pad P
2 contacts with the conducting pads P
3 and P
4 in order to establish the connection between the nodes N
1 and N
2. Therefore, the nodes N
1 and N
2 are short-circuited by the conducting pad P
2, and consequently the dryer circuit 1 700 operates in mode 1.
[0053] Please refer to FIG. 23. FIG. 23 is a diagram illustrating the connection controller
2001 in mode 3. As shown in FIG. 23, the slide button T moves further downward so
that the conducting pad P
2 contacts with the conducting pads P
5 and P
6 in order to establish the connection between the nodes N
3 and N
4, and the conducting pad P
1 contacts with the conducting pads P
3 and P
4 in order to establish the connection between the nodes N
1 and N
2. Therefore, the nodes N
1 and N
2 are short-circuited by the conducting pad P
1, the nodes N
3 and N
4 are short-circuited by the conducting pad P
2, and consequently the dryer circuit 1700 operates in mode 3.
[0054] Please refer to FIG. 24. FIG. 24 is a diagram illustrating another connection controller
2400 of the second embodiment of the present invention. As shown in FIG. 24, the connection
controller 2400 comprises a transistor Q
1 controlled by a switch SW
3 for the connection between the nodes N
1 and N
2, and a transistor Q
2 controlled by a switch SW
4 for the connection between the nodes N
3 and N
4. The transistor Q
1 connects the node N
1 to the node N
2 when the switch SW
3 is short-circuited for transmitting the voltage V
B from the power unit B and the control end of the transistor Q
1 receives the voltage V
B from the power unit B. The transistor Q
2 connects the node N
3 to the node N
4 when the switch SW
4 is short-circuited for transmitting the voltage V
B from the power unit B and the control end of the transistor Q
2 receives the voltage V
B from the power unit B. The voltages on the control ends of the transistors Q
1 and Q
2 for actuating the transistors Q
1 and Q
2 can be positive or negative, depending on the transistors being forward-biased or
reverse-biased. The switches SW
3 and SW
4 are coupled in parallel for being respectively controlled in order to achieve the
operation of the dryer circuit 1700 in modes 0, 1 and 3.
[0055] Please refer to FIG. 25. FIG. 25 is a diagram illustrating the connection controller
2401 based on the connection controller 2400 and utilizing a slide switch SWT of the
present invention. As shown in FIG. 25, the slide switch SWT is disposed for controlling
the connection between the nodes N
1 and N
2 and the connection between the nodes N
3 and N
4. The dryer circuit 1700 operates in modes 0, 1 and 3 according to the movement of
the slide button T of the slide switch SWT as described from FIG. 21 to FIG. 23 and
the related description is omitted.
[0056] Please refer to FIG. 26. FIG. 26 is a diagram illustrating another connection controller
2600 of the second embodiment of the present invention. As shown in FIG. 26, the connection
controller 2600 comprises two transistors Q
1 and Q
2 both controlled by a slide switch SWT, a pad P
2 connected to the power unit B, a pad P
1 connected to the control end of transistor Q
1, and a pad P
3 connected to the control end of transistor Q
1 through diode D
3 and to the control end of transistor Q
2. The slide switch SWT comprises a base H, a slide button T, and a conducting pad
C.
[0057] By default setting, the connection controller 2600 achieves mode 0 operation for
the dryer circuit 1700 by disposing the slide button T in a position that conducting
pad C contacts with no pads but only the pad P
1.
[0058] When the slide button T of the slide switch SWT shifts to the position for mode 1,
the pad P
1 and the pad P
2 are short-circuited by the conducting pad C, so the control end of the transistor
Q
1 receives the voltage V
B from the power unit B. Therefore, the transistor Q
1 connects the node N
1 to the node N
2. The diode D
3 prevents the transistor Q
2 from receiving the voltage V
B from the power unit B when the pad P
1 and the pad P
2 are short-circuited.
[0059] When the slide button T of the slide switch SWT shifts to the position for mode 3,
the pad P
2 and the pad P
3 are short-circuited by the conducting pad C, so both the control ends of the transistors
Q
1 and Q
2 receive the voltage V
B from the power unit B. Therefore, the transistor Q
1 connects the node N
1 to the node N
2 and the transistor Q
2 connects the node N
3 to the node N
4.
[0060] In summary, the dryer circuit 1700 can operate in modes 0, 1, and 3 by shifting the
slide button T of the slide switch SWT to different positions.
[0061] Please refer to FIG. 27. FIG. 27 is a diagram illustrating another connection controller
2700 of the second embodiment of the present invention. As shown in FIG. 27, the connection
controller 2700 comprises a transistor Q
1 controlled by a switch SW
3 for the connection between the nodes N
1 and N
2, and a transistor Q
2 controlled by a switch SW
4 for the connection between the nodes N
3 and N
4. The transistor Q
1 connects node N
1 to node N
2 when the switch SW
3 is short-circuited for transmitting the voltage V
B from the power unit B and the control end of the transistor Q
1 receives the voltage V
B from the power unit B. The transistor Q
2 connects node N
3 to the node N
4 only when both switch SW
3 and switch SW
4 are short-circuited for transmitting the voltage V
B from the power unit B and the control end of the transistor Q
2 receives a voltage from the power unit B. The voltages on the control ends of the
transistors Q
1 and Q
2 can be positive or negative, depending on the transistors being forward-biased or
reverse-biased. The switches SW
3 and SW
4 are coupled in series for being respectively controlled to achieve the operation
of the dryer circuit 1700 in modes 0, 1 and 3.
[0062] Please refer to FIG. 28. FIG. 28 is a diagram illustrating the connection controller
2701 based on the connection controller 2700 and utilizing a slide switch SWT of the
present invention. As shown in FIG. 28, the slide switch SWT is disposed for controlling
the connection between the nodes N
1 and N
2 and the connection between the nodes N
3 and N
4. The dryer circuit 1700 operates in modes 0, 1 and 3 according to the movement of
the button T of the slide switch SWT as described from FIG. 21 to FIG. 23 and the
related description is omitted.
[0063] Please refer to FIG. 35. FIG. 35 is a diagram illustrating alternative embodiment
of the second embodiment of the present invention. As shown in FIG.35, the dryer circuit
3500 is similar to the dryer circuit 1700 in FIG. 17, but the difference between the
two dryer circuits is: the node N
1 is disposed at the second end of the power unit B, and the node N
2 is disposed at the second end of the first heating unit HG
1.
[0064] Please refer to FIG. 29. FIG. 29 is a diagram illustrating a third embodiment of
the present invention. As shown in FIG.29, the dryer circuit 2900 comprises a main
circuit 2910 and a connection controller 2920. The main circuit 2910 comprises a power
unit B, a motor M (including a fan), a diode D
1, two heating units HG
1, and HG
2, a resistor R
1, and three nodes N
1, N
2, and N
3. The power unit B provides a voltage V
B. The heating units HG
1 and HG
2 generate heat according to power consumed by the heat units HG
1, and HG
2 respectively. The motor M (including a fan) generates airflow with a volume according
to the power consumed by the motor M.
[0065] Between the positive end of the power unit B and the node N
1, the heating unit HG
1, the motor M, and the resistor R
1 form a circuit group G
3. In the circuit group G
3, the motor M and the resistor R
1 are coupled in series, and the motor M and the heating unit HG
1 are coupled in parallel.
[0066] Between the positive end of the power unit B and the node N
3, the heating unit HG
2, the motor M, and the diode D
1, form a circuit group G
4. In the circuit group G
4, the motor M and the diode D
1 are coupled in series, and the motor M and the heating unit HG
2 are coupled in parallel.
[0067] The connection controller 2920 controls the connection between the nodes N
1 and N
2, and the connection between the nodes N
2 and N
3, respectively. Therefore, by controlling the current to flow through the circuit
groups G
3, or both the circuit groups G
3 and G
4, different modes of the dryer circuit 2900 are achieved.
[0068] The dryer circuit 2900 utilizes the connection controller 2920 to perform the same
operating modes 0, 1 and 3 as described from FIG. 17 to FIG. 19 for the dryer circuit
1700 and the related description is omitted. The calculations of the power consumptions
on the components in the main circuit 2910 in modes 1 and 3 are similar to FIG. 3
and FIG. 7, which are also omitted.
[0069] Please refer to FIG. 30. FIG. 30 is a diagram illustrating a first connection controller
2901 of the third embodiment of the present invention. As shown in FIG. 30, the slide
switch SWT is disposed for controlling the connection between the nodes N
1 and N
2 and the connection between the nodes N
2 and N
3. The dryer circuit 2900 operates in modes 0, 1 and 3 according to the movement of
the slide button T of the slide switch SWT as described from FIG. 21 to FIG. 23 and
the related description is omitted.
[0070] Please refer to FIG. 31. FIG. 31 is a diagram illustrating another connection controller
3100 of the third embodiment of the present invention. As shown in FIG. 31 , the connection
controller 3100 comprises a transistor Q
1 for the connection between the nodes N
1and N
2, a transistor Q
2 for the connection between the nodes N
2 and N
3, and a slide switch SWT for controlling both transistors Q
1 and Q
2.The voltage on the control ends of the transistors Q
1 and Q
2 can be positive or negative, depending on the transistors being forward-biased or
reverse-biased. The dryer circuit 2900 operates in modes 0, 1 and 3 according to the
movement of the slide switch SWT also as described from FIG. 21 to FIG. 23 and the
related description is omitted.
[0071] Please refer to FIG. 32. FIG. 32 is a diagram illustrating another connection controller
3200 of the third embodiment of the present invention. As shown in FIG. 32, the connection
controller 3200 comprises two transistors Q
1 and Q
2 both controlled by a slide switch SWT, a pad P
2 connected to the power unit B, a pad P
1 connected to the control end of transistor Q
1, and a pad P
3 connected to the control end of transistor Q
1 through diode D
3 and to the control end of transistor Q
2. The slide switch SWT comprises a base H, a slide button T, and a conducting pad
C. The dryer circuit 2900 operates in modes 0, 1 and 3 according to the movement of
the slide button T of the slide switch SWT as described in FIG. 26 and the related
description is omitted.
[0072] Please refer to FIG. 33. FIG. 33 is a diagram illustrating another connection controller
3300 of the third embodiment of the present invention. As shown in FIG. 33, the connection
controller 3300 comprises a transistor Q
1 controlled by a switch SW
3 for the connection between the nodes N
1 and N
2, and a transistor Q
2 controlled by a switch SW
4 for the connection between the nodes N
2 and N
3. The switches SW
3 and SW
4 are coupled in series for respectively being controlled to achieve the operation
of the dryer circuit 2900 in modes 0, 1 and 3 as described in FIG. 27 and the related
description is omitted.
[0073] Please refer to FIG. 34. FIG. 34 is a diagram illustrating the connection controller
3301 based on the connection controller 3300 and utilizing a slide switch SWT of the
present invention. As shown in FIG. 34, the slide switch SWT is disposed for controlling
the connection between the nodes N
1 and N
2 and the connection between the nodes N
2 and N
3. The dryer circuit 2900 operates in modes 0, 1 and 3 according to the movement of
the slide button T of the slide switch SWT as described from FIG. 21 to FIG. 23 and
the related description is omitted.
[0075] Additionally, the power unit mentioned in the present invention can be realized with
battery, rechargeable battery, fuel cell, micro-engine, or any device providing electric
power and should not be limited to the embodiments mentioned above. The heating units
mentioned in the present invention can be realized with heating filaments, or any
devices with impedance for generating heat by consuming electric power and should
not be limited to the embodiment mentioned above. The transistors mentioned in the
present invention can be realized with any electronic switches including but not limited
to MOSFET (metal-oxide semiconductor field-effect transistor), JFET (junction field-effect
transistor), SCR (silicon-controlled rectifier), UJT (uni-junction transistor) and
so on. Further, the resistor mentioned in the present invention also can be replaced
by and utilized as a heating unit, and the slide switch mentioned in the present invention
also can be replaced with other kinds of switches such as rotary switches or push-button
switches.
[0076] To sum up, the present invention provides various innovative dryer circuits to achieve
multi-setting of the portable dryer. Particularly, the dry circuits utilize the connection
controller to control the power consumed by the motor and the power consumed by the
heating units at the same time for generating various volume of airflow at the desired
heat output.
[0077] In conclusion, the invention can be summarized as a dryer circuit comprising a main
circuit and a connection controller. The dryer circuit comprises a power unit, a first
and second heating units, a first and a second switches, a motor having a fan installed,
a resistor, a first diode, and a second diode. The first and the second heating units
are coupled to ground respectively through the first and the second switches. The
resistor is coupled between the first heating unit and the motor. The first diode
is coupled between the second heating unit and the motor. The second diode is coupled
between the first heating unit and the motor and in series with the resistor. The
connection controller controls the first and the second switches on or off for adjusting
the power supplied to the motor, and the first and the second heating units at the
same time.
[0078] All combinations and sub-combinations of the above-described features also belong
to the invention.
1. A dryer circuit (2900) comprising:
a main circuit (2910), comprising:
a power unit (B), comprising:
a first end for providing a first predetermined voltage (VB); and
a second end for providing a second predetermined voltage;
a first heating unit (HG1), comprising:
a first end coupled to the first end of the power unit (B); and
a second end;
a second heating unit (HG2), comprising:
a first end coupled to the first end of the power unit (B); and
a second end;
a fan motor (M), comprising:
a first end coupled to the first end of the power unit (B); and
a second end;
a diode (D1) coupled between the second end of the second heating unit (HG2) and the second end of the fan motor (M); and
a resistor (R1) coupled between the second of the first heating unit (HG1) and the second end of the fan motor (M); and characterized by:
a connection controller (2920) coupled to the second end of the first heating unit
(HG1), the second end of the second heating unit (HG2), and the second end of the power unit (B) for switching coupling of the second end
of the first heating unit (HG1) to the second end of the power unit (B) and switching coupling of the second end
of the second heating unit (HG2) to the second end of the power unit (B).
2. The dryer circuit (2900) of claim 1 characterized in that the connection controller (2920) comprises a switching device (2920) for coupling
the second end of the first heating unit (HG1) to the second end of the power unit (B), or coupling the second end of the second
heating unit (HG2) to the second end of the power unit (B), or coupling both the second ends of the
first and the second heating units (HG1, HG2) to the second end of the power unit (B).
3. The dryer circuit (2900) of claim 1
characterized in that the switching device (800) comprises:
a first switch (SW1) coupled between the second end of the power unit (B) and the second end of the first
heating unit (HG1) for coupling the second end of the power unit (B) to the second end of the first
heating unit (HG1); and
a second switch (SW2) coupled between the second end of the power unit (B) and the second end of the second
heating unit (HG2) for coupling the second end of the power unit (B) to the second end of the second
heating unit (HG2).
4. The dryer circuit (2900) of claim 1
characterized in that the connection controller (3100) comprises:
a first electronic switch (Q1), comprising:
a first end coupled to the second end of the first heating unit (HG1);
a second end coupled to the second end of the power unit (B); and
a control end;
characterized in that the first end of the first electronic switch (Q1) is coupled to the second end of the first electronic switch (Q1) when the control end of the first electronic switch (Q1) receives the first predetermined voltage (VB);
a second electronic switch (Q2), comprising:
a first end coupled to the second end of the second heating unit (HG2);
a second end coupled to the second end of the power unit (B); and
a control end;
characterized in that the first end of the second electronic switch (Q2) is coupled to the second end of the second electronic switch (Q2) when the control end of the second electronic switch (Q2) receives the first predetermined voltage (VB); and
a switching device (2400) for coupling the control end of the first electronic switch
(Q1) to the first end of the power unit (B) or coupling the control end of the second
electronic switches (Q2) to the first end of the power unit (B).
5. The dryer circuit (3200) of claim 4
characterized in that the switching device (3200) comprises:
a first conducting pad (P2) coupled to the first end of the power unit;
a second conducting pad (P1) coupled to the control end of the first electronic switch (Q1);
a diode (D3) coupled between the control end of the first electronic switch (Q1) and the control end of the second electronic switch (Q2);
a third conducting pad (P3) coupled to the control end of the second electronic switch (Q2); and
a slide switch (SWT), comprising:
a slide button (T); and
a contact (C);
characterized in that when the slide button (T) moves to a first position, the contact (C) is accordingly
moved for coupling the first conducting pad (P2) to the second conducting pad (P1); when the slide button (T) moves to a second position, the contact (C) is accordingly
moved for coupling the first conducting pad (P2) to the third conducting pad (P3).
6. The dryer circuit (100) of claim 1 is further
characterized by:
a second diode (D2) coupled to the resistor (R1) in series and coupled between the second end of the fan motor (M) and the second
end of the first heating unit (HG1);
wherein the connection controller (120) may comprise a switching device (800) for
coupling the second end of the first heating unit (HG
1) to the second end of the power unit (B), or coupling the second end of the second
heating unit (HG
2) to the second end of the power unit (B), or coupling both the second ends of the
first and the second heating units (HG
1, HG
2) to the second end of the power unit (B).
7. The dryer circuit (100) of claim 6
characterized in that the connection controller (1 300) comprises:
a first electronic switch (Q1), comprising:
a first end coupled to the second end of the first heating unit (HG1);
a second end coupled to the second end of the power unit (B); and
a control end;
characterized in that the first end of the first electronic switch (Q1) is coupled to the second end of the first electronic switch (Q1) when the control end of the first electronic switch (Q1) receives the first predetermined voltage (VB);
a second electronic switch (Q2), comprising:
a first end coupled to the second end of the second heating unit (HG2);
a second end coupled to the second end of the power unit (B); and
a control end;
characterized in that the first end of the second electronic switch (Q2) is coupled to the second end of the second electronic switch (Q2) when the control end of the second electronic switch (Q2) receives the first predetermined voltage (VB); and
a switching device (1300) for coupling the control end of the first electronic switch
(Q1) to the first end of the power unit (B), or coupling the control end of the second
electronic switch (Q2) to the first end of the power unit (B), or coupling both the control ends of the
first and the second electronic switches (Q1,Q2) to the first end of the power unit (B).
8. The dryer circuit (100) of claim 7
characterized in that the switching device (1 500) comprises:
a first conducting pad (P6) coupled to the first end of the power unit;
a second conducting pad (P8) coupled to the first end of the power unit;
a third conducting pad (P10) coupled to the first end of the power unit;
a fourth conducting pad (P5) coupled to the control end of the first electronic switch (Q1);
a fifth conducting pad (P7) coupled to the control end of the second electronic switch (Q2);
a first diode (D4) coupled to the control end of the second electronic switch (Q2);
a sixth conducting pad (P9) coupled to the control end of the second electronic switch (Q2) through the first diode (D4);
a second diode (D3) coupled between the control end of the first electronic switch (Q1) and the sixth conducting pad (P9); and
a slide switch (SWT), comprising:
a slide button (T); and
a contact (P1);
characterized in that when the slide button (T) moves to a first position, the contact (P1) is accordingly moved for coupling the first conducting pad (P6) and the fourth conducting pad (P5); when the slide button (T) moves to a second position, the contact (P1) is accordingly moved for coupling the second conducting pad (P8) and the fifth conducting pad (P7); when the slide button (T) moves to a third position, the contact (P1) is accordingly moved for coupling the third conducting pad (P10) and the sixth conducting pad (P9).
9. A dryer circuit (1 700) comprising:
a main circuit (1 710), comprising:
a power unit (B), comprising:
a first end for providing a first predetermined voltage (VB); and
a second end for providing a second predetermined voltage;
a first heating unit (HG1), comprising:
a first end; and
a second end coupled to the second end of the power unit (B);
a second heating unit (HG2), comprising:
a first end coupled to the first end of the first heating unit (HG1); and
a second end;
a fan motor (M), comprising:
a first end coupled to the first end of the first heating unit (HG1); and
a second end;
a diode (D1) coupled between the second end of the second heating unit (HG2) and the second end of the fan motor (M); and
a resistor (R1) coupled between the second of the first heating unit (HG1) and the second end of the fan motor (M); and characterized by:
a connection controller (1 720) coupled to the power unit (B), the first heating unit
(HG1), and the second heating unit (HG2), for switching coupling between the first heating unit (HG1), the power unit (B), and the second heating unit (HG2).
10. The dryer circuit (1700) of claim 9
characterized in that the connection controller (1720) comprises a switching device (1 720) for coupling
the first end of the first heating unit (HG
1) to the first end of the power unit (B) or coupling the first end of the first heating
unit (HG
1) to the first end of the power unit (B) and the second end of the second heating
unit (HG
2) to the second end of the power unit (B); wherein the switching device (1720) may
comprise:
a first switch (SW1) coupled between the first end of power unit (B) and the first end of the first heating
unit (HG1); and
a second switch (SW2) coupled between the second end of the power unit (B) and the second end of the second
heating unit (HG2).
11. The dryer circuit (1700) of claim 9
characterized in that the connection controller (1 720) comprises:
a first electronic switch (Q1), comprising:
a first end coupled to the first end of the first heating unit (HG1);
a second end coupled to the first end of the power unit (B); and
a control end;
characterized in that the first end of the first electronic switch (Q1) is coupled to the second end of the first electronic switch (Q1) when the control end of the first electronic switch (Q1) receives the first predetermined voltage (VB);
a second electronic switch (Q2), comprising:
a first end coupled to the second end of the second heating unit (HG2);
a second end coupled to the second end of the power unit (B); and
a control end;
characterized in that the first end of the second electronic switch (Q2) is coupled to the second end of the second electronic switch (Q2) when the control end of the second electronic switch (Q2) receives the first predetermined voltage (VB); and
a switching device (2400) for coupling the control end of the first electronic switch
(Q1) to the first end of the power unit (B), or coupling both the control ends of the
first and the second electronic switches (Q1, Q2) to the first end of the power unit (B).
12. The dryer circuit (1700) of claim 11
characterized in that the switching device (2600) comprises:
a first conducting pad (P2) coupled to the first end of the power unit (B);
a second conducting pad (P1) coupled to the control end of the first electronic switch (Q1);
a third conducting pad (P3) coupled to the control end of the second electronic switch (Q2);
a diode (D3) coupled between the control end of the first electronic switch (Q1) and the control end of the second electronic switch (Q2); and
a slide switch (SWT), comprising:
a slide button (T); and
a contact (C);
characterized in that when the slide button (T) moves to a first position, the contact (C) is accordingly
moved for coupling the first conducting pad (P2) and the second conducting pad (P1); when the slide button (T) moves to a second position, the contact (C) is accordingly
moved for coupling the first conducting pad (P2) and the third conducting pad (P3).
13. A dryer circuit (3500) comprising:
a main circuit (3510), comprising:
a power unit (B), comprising:
a first end for providing a first predetermined voltage (VB); and
a second end for providing a second predetermined voltage;
a first heating unit (HG1), comprising:
a first end coupled to the first end of the power unit (B); and
a second end;
a second heating unit (HG2), comprising:
a first end coupled to the first end of the first heating unit (HG1); and
a second end;
a fan motor (M), comprising:
a first end coupled to the first end of the first heating unit (HG1); and
a second end;
a diode (D1) coupled between the second end of the second heating unit (HG2) and the second end of the fan motor (M); and
a resistor (R1) coupled between the second of the first heating unit (HG1) and the second end of the fan motor (M); and characterized by:
a connection controller (3520) coupled to the power unit (B), the first heating unit
(HG1), and the second heating unit (HG2), for switching coupling between the second end of the first heating unit (HG1) and the second end of the power unit (B), and between the second end of the second
heating unit (HG2) and the second end of the first heating unit (HG1).
14. The dryer circuit (3500) of claim 13 characterized in that the connection controller (3520) comprises a switching device for coupling the second
end of the first heating unit (HG1) to the second end of the power unit (B) or coupling the second end of the first
heating unit (HG1) to the second end of the power unit (B) and the second end of the second heating
unit (HG2) to the second end of the first heating unit (HG1).
15. The dryer circuit (2900, 100, 1700, 3500) of claims 1, 6, 9, or 13 characterized in that when the first predetermined voltage (VB) is higher than the second predetermined voltage, a positive end of the diode (D1) is coupled to the second end of the fan motor (M), and a negative end of the diode
(D1) is coupled to the second end of the second heating unit (HG2); a positive end of the second diode (D2) is coupled to the second end of the fan motor (M), and a negative end of the second
diode (D2) is coupled to the second end of the first heating unit (HG1).
16. The dryer circuit (2900, 100, 1700, 3500) of claims 1, 6, 9, or 13 characterized in that when the first predetermined voltage (VB) is lower than the second predetermined voltage, a negative end of the diode (D1) is coupled to the second end of the fan motor (M), and a positive end of the diode
(D1) is coupled to the second end of the second heating unit (HG2); a negative end of the second diode (D2) is coupled to the second end of the fan motor (M), and a positive end of the second
diode (D2) is coupled to the second end of the first heating unit (HG1).