TWI381098B - Positive and negative rotation control circuit for fan - Google Patents

Description

Fan forward and reverse control circuit

The invention relates to a rotation control circuit of a fan, in particular to a control circuit capable of controlling the forward and reverse rotation of a fan motor.

In order to effectively dissipate the heat generated by the electronic product during operation, the conventional technology is usually operated by a heat-dissipating fan to achieve rapid heat dissipation of the electronic product. In the heat-dissipating operation of the cooling fan, the cooling fan rotates in a predetermined rotation direction to guide the external airflow into the interior of the electronic product, and is thermally dissipated by the heat source, but the external airflow is introduced into the electronic product in a large amount. Therefore, it is easy to accumulate dust inside the electronic product; therefore, at the beginning of the starting operation of the electronic product, the cooling fan is usually controlled to rotate in a direction opposite to the predetermined rotation direction for a period of time (for example, 5 seconds), so that the cooling fan can The dust inside the electronic product is guided to the outside to perform the dust removal operation inside the electronic product; after that, the cooling fan is controlled to rotate in the predetermined rotation direction to perform the heat dissipation operation.

In order to achieve the purpose of controlling the heat dissipation of the cooling fan after dust removal, as shown in FIG. 1, the positive and negative control circuit of the conventional fan is disclosed, which comprises a driving unit 91 and a microcontroller 92. The driving unit 91 and the microcontroller 92 are respectively connected to a voltage source VCC, so that the voltage source VCC can be supplied to the driving unit 91 and the required power of the microcontroller 92. The driving unit 91 is electrically connected to the microcontroller. 92, and the driving unit 91 is electrically connected to a fan motor 8.

When the conventional fan is activated, the microcontroller 92 sends a rotation signal and inputs the drive unit 91 so that the drive unit 91 can control the fan motor 8 to rotate in the predetermined rotation direction to perform the dust removal operation.

After the conventional fan is dusted for a period of time, the microcontroller 92 sends a reverse rotation signal opposite to the rotation signal, so that the driving unit 91 can control the fan motor 8 to rotate in a direction opposite to the predetermined rotation direction. For heat dissipation work.

However, in general, the forward and reverse control circuit of the conventional fan described above has the following disadvantages: the conventional fan needs to use the microcontroller 92 to generate the rotation signal and the reverse rotation signal to control the forward and reverse rotation thereof due to the micro The controller 92 is a high unit price component, so that the fan controls the fan motor 8 to rotate using the microcontroller 92, which inevitably causes an increase in circuit cost. For the above reasons, it is necessary to further improve the forward and reverse control circuit of the above conventional fan.

The object of the present invention is to provide a forward and reverse control circuit for a fan, which is composed of only a plurality of analog circuit components, and avoids using a microcontroller to control a fan motor to reverse the current to reduce the circuit installation cost.

The forward and reverse control circuit of the fan according to the present invention comprises: a drive control unit and a steering switching control unit, the drive control unit is electrically connected to a fan motor; the steering switching control unit is only composed of a plurality of analog circuit components The steering switching control unit is electrically connected to the driving control unit, and the steering switching control unit generates a forward/reverse switching signal group, and controls the fan motor to rotate in a predetermined rotation direction for a period of time after starting, and then controls the The fan motor rotates in a direction opposite to the predetermined rotational direction.

The above and other objects, features and advantages of the present invention will become more <RTIgt; It discloses a forward and reverse control circuit for a fan according to a first embodiment of the present invention, which includes a drive control unit 1 and a steering switching control unit 2, and the drive control unit 1 and the steering switching control unit 2 are commonly connected to a power supply. VCC. The drive control unit 1 is connected to a fan motor 6; the steering switch control unit 2 is composed of only a plurality of analog circuit components, such as a charge and discharge circuit, and the steering switch control unit 2 is electrically connected to the drive control unit. In addition, the present invention further has a storage capacitor C for storing electrical energy, so that when the supply power source VCC is interrupted, the power of the fan can be provided. The steering switching control unit 2 can generate a forward/reverse switching signal group for the driving control unit 1 to receive, thereby controlling the fan motor 6 to rotate in a predetermined rotation direction for a period of time after starting, and then controlling the fan motor 6 Rotating in the opposite direction to the predetermined direction of rotation.

Referring to FIG. 2 again, in further words, the forward/reverse switching signal group includes a forward rotation control signal and a reverse rotation control signal, and the driving control unit 1 can receive the forward rotation control signal and The reverse rotation control signal is respectively converted to generate a low level logic signal and a high level logic signal, and after the forward rotation control signal is maintained for output for a predetermined time, the reverse rotation control signal is switched and outputted according to A control is achieved in which the fan motor 6 is first rotated in the predetermined rotational direction for a period of time and then rotated in the opposite direction to the predetermined rotational direction.

Referring to FIG. 2 again, the steering switching control unit 2 of the first embodiment of the present invention includes a resistor 21 and a capacitor 22. The resistor 21 and the capacitor 22 form the charging and discharging circuit. The series connection of the resistor 21 and the capacitor 22 is a signal output end. The signal output end is coupled to the driving control unit, that is, the capacitor 22 is connected in parallel. The drive control unit 1.

Referring to Figures 2, 3a and 3b, when the fan of the present invention is activated, the power supply VCC charges the capacitor 22, and the charging voltage curve is as shown in Fig. 3a, wherein the capacitor of the first embodiment of the present invention The charging voltage of 22 can be used as the forward/reverse switching signal group for the driving control unit 1 to receive.

Furthermore, please refer to FIG. 3b at the same time, after receiving the charging voltage, the driving control unit 1 will use a low threshold voltage VL (such as 1V) and a high threshold voltage VH (such as 4V) as a basis for judging, In order to convert the charging voltage into a low level logic signal or a high level logic signal. For example, when the received charging voltage signal does not reach the low threshold voltage VL of the driving control unit 1, the driving control unit 1 converts the charging voltage at this time into a low level logic signal; in contrast, when the received charging When the voltage signal level is higher than the high threshold voltage VH, the drive control unit 1 converts the charging voltage into a high level logic signal.

In other words, in the process of charging the capacitor 22 from 0V to the low threshold voltage VL, the driving control unit 1 will regard the segment charging time T1 as the forward rotation control signal, and at this time, the driving control unit 1 controls the fan motor. 6 is rotated in the predetermined rotation direction for a period of time (the period of time is the same as the charging time T1); if the charging voltage of the capacitor 22 exceeds the threshold voltage VH of the driving control unit 1, it is determined as The reverse rotation control signal is controlled by the drive control unit 1 to rotate the fan motor 6 in a direction opposite to the predetermined rotation direction. The length of the charging time T1 can be adjusted by appropriately designing the resistance of the resistor 21 and the capacitance of the capacitor 22.

In addition, when the driving control unit 1 according to the first embodiment of the present invention receives the intermediate voltage between the low threshold voltage VL and the high threshold voltage VH, the driving control unit 1 cannot determine that the driving control unit 1 is The high level logic signal or the low level logic signal, therefore, the fan motor 6 will stop rotating during the charging time T2 of the intermediate potential, until the charging voltage is higher than the high threshold voltage VH, the fan motor 6 Respond to the rotation state.

Referring to FIG. 4, a forward and reverse control circuit of a fan according to a second embodiment of the present invention is disclosed. Compared with the first embodiment, the steering switching control unit 3 of the second embodiment of the present invention includes a resistor 31. a capacitor 32 and a discharge loop diode 33. The resistor 31 and the capacitor 32 form the charging and discharging circuit, and the capacitor 32 is connected in parallel to the driving control unit 1; the discharging circuit diode 33 is connected in reverse parallel to the resistor 31, that is, the discharging circuit diode 33 An anode is connected to one of the signal output terminals of the charge and discharge circuit.

Thereby, when the fan stops running, the charging voltage of the capacitor 32 can be quickly discharged by one of the discharge paths formed by the resistor 31 and the discharge loop diode 33. In other words, if only the capacitor 32 is used for discharging, a long discharge time is required. Therefore, in the second embodiment of the present invention, the discharge path is set to shorten the discharge time, thereby improving the smoothness of the fan to start the operation again in a short time. .

Referring to FIG. 5, a forward and reverse control circuit of a fan according to a third embodiment of the present invention is disclosed. Compared with the second embodiment, the steering switching control unit 4 of the third embodiment of the present invention includes a resistor 41. A capacitor 42, a discharge loop diode 43, and a transistor switch 44. The circuit connection state and the action of the resistor 41, the capacitor 42 and the discharge loop diode 43 are the same as those of the resistor 31, the capacitor 32 and the discharge loop diode 33 of the second embodiment, and the details are not described herein. .

Referring to FIG. 5 again, the output end of the transistor switch 44 of the third embodiment of the present invention is electrically connected to the resistor 41 and the capacitor 42 is connected to form a signal output terminal for charging the capacitor 42. The voltage can control the on or off of the transistor switch 44; further, the transistor switch 44 is connected in parallel to the drive control unit 1, that is, one of the output terminals (set extreme or 汲 extreme) of the transistor switch 44 is electrically connected. The drive control unit 1. The transistor switch 44 can be selected from an N-type transistor such as an NPN transistor or an NMOS transistor.

Further, when the charging voltage does not reach a turn-on voltage of the transistor switch 44, the transistor switch 44 forms an open circuit, and the driving control unit 1 receives the voltage of the power supply VCC and determines that it is a high level logic. The signal; conversely, when the charging voltage exceeds the turn-on voltage of the transistor switch 44, the transistor switch 44 is turned on and grounded, and the drive control unit 1 receives the low level logic signal at this time.

As can be seen from the above, since the transistor switch 44 of the third embodiment of the present invention operates only in the on or off state, the steering switching control unit 4 can quickly perform the logic signal alignment as compared with the first embodiment and the second embodiment. The switching operation of the bit can avoid the problem that the fan stops running due to the intermediate potential, so that the smooth running of the fan can be further improved.

Furthermore, the steering switching control unit 4 of the third embodiment of the present invention can also operate with the discharge loop diode 43 omitted, thereby reducing circuit installation cost and simplifying circuit connection complexity.

Referring to FIG. 6, a forward and reverse control circuit for a fan according to a fourth embodiment of the present invention is disclosed. Compared with the third embodiment, the steering switching control unit 5 of the fourth embodiment of the present invention includes a resistor 51. A capacitor 52, a discharge loop diode 53, a first voltage dividing resistor 54, a second voltage dividing resistor 55 and a comparator 56. The circuit connection state and the action of the resistor 51, the capacitor 52 and the discharge loop diode 53 are the same as those of the resistor 31, the capacitor 32 and the discharge loop diode 33 of the second embodiment, and the details are not described herein. .

Referring to FIG. 6 again, the first voltage dividing resistor 54 and the second voltage dividing resistor 55 of the fourth embodiment of the present invention are connected in series to each other to form a voltage dividing network having a voltage dividing output. And the voltage dividing network is connected between the power supply VCC and the ground, so as to establish a comparison voltage at the voltage dividing output of the voltage dividing network, the comparison voltage is the cross of the second voltage dividing resistor 55 Pressure.

The comparator 56 has a positive input 561 and a negative input 562. The resistor 51 and the capacitor 52 are connected to form a signal output terminal electrically connected to the positive input terminal 561 of the comparator 56; and the voltage dividing output terminal of the voltage dividing network is electrically connected to the comparator 56. The negative input terminal 562, such that the charging voltage of the capacitor 52 and the comparison voltage of the second voltage dividing resistor 55 can be input into the comparator 56 for comparison, so that the comparator 56 determines the output high level logic signal or the output low level a bit logic signal, that is, when the charging voltage does not reach the comparison voltage (ie, less than the comparison voltage), the comparator 56 outputs a low level logic signal; otherwise, when the charging voltage exceeds the comparison voltage (ie, greater than the When comparing voltages, the comparator 56 outputs a high level logic signal.

The comparison voltage of the fourth embodiment of the present invention can be set by adjusting the individual resistance values of the first voltage dividing resistor 54 and the second voltage dividing resistor 55 to set the voltage value of the comparison voltage. For example, the supply power source VCC is 5V. If the ratio of the resistance value of the first voltage dividing resistor 54 to the resistance value of the second voltage dividing resistor 55 is 1:4, the comparison voltage is 4V.

Furthermore, since the output of the comparator 56 also has only the switching state of the high level logic and the low level logic, the fourth embodiment of the present invention is compared to the steering switching control unit 2 of the first and second embodiments. In this case, the problem that the fan is stopped due to the intermediate potential can also be avoided.

In addition, since the voltage value of the comparison voltage can be increased by the design of the two voltage dividing resistors 54 and 55 according to the fourth embodiment of the present invention, and the comparison voltage can be designed to be larger than the low threshold voltage VL of the driving control unit 1, the phase Compared with the steering switching control unit 2 of the first and second embodiments, the capacitor 52 of the fourth embodiment of the present invention can select a smaller rated capacitor under the condition that the same charging time T1 is maintained.

Moreover, the steering switching control unit 5 of the fourth embodiment of the present invention can also operate with the discharge loop diode 53 omitted, thereby reducing the circuit installation cost and simplifying the circuit connection complexity.

The forward and reverse rotation control circuit of the fan according to the first to fourth embodiments of the present invention uses the charging voltage as the forward/reverse switching signal group to control the rotation of the fan motor 6. Conversely, the forward and reverse control circuit can also use a discharge voltage as the set of forward and reverse switching signals for inverse logic control.

Referring to FIG. 7, which discloses a forward and reverse control circuit for a fan according to a fifth embodiment of the present invention, the steering switching control unit 2' of the fifth embodiment of the present invention is a resistor as compared with the first embodiment. 21' and a capacitor 22' form the charge and discharge circuit, and the resistor 21' is connected in parallel to the drive control unit 1. The steering switching control unit 2' switches the discharge control voltage of the driving control unit 1 of the second embodiment from a high-level logic signal to a low-level logic signal by the operation of the discharge voltage of the resistor 21'.

Referring to FIG. 8, which discloses a forward and reverse control circuit for a fan according to a sixth embodiment of the present invention, the steering switching control unit 3' of the sixth embodiment of the present invention includes a resistor 31 compared to the second embodiment. ', a capacitor 32' and a discharge loop diode 33'. The discharge circuit diode 33' is connected in parallel to the resistor 31', and one of the discharge circuit diodes 33' is connected to a signal output terminal of the charge and discharge circuit. Thereby, the drive control unit 1 can switch the discharge voltage from a high level logic signal to a low level logic signal.

Referring to FIG. 9, a forward and reverse control circuit for a fan according to a seventh embodiment of the present invention is disclosed. Compared with the third embodiment, the steering switching control unit 4' of the seventh embodiment of the present invention includes a resistor 41. ', a capacitor 42', a discharge loop diode 43' and a transistor switch 44'. The transistor switch 44' is electrically connected to the resistor 41' and the capacitor 42' is connected to form a signal output terminal, so that the discharge voltage of the resistor 41' can control the transistor switch 44' to be turned on or off. The transistor switch 44 can be selected from a P-type transistor such as a PNP transistor or a PMOS transistor.

Referring to FIG. 10, a forward/reverse control circuit for a fan according to an eighth embodiment of the present invention is disclosed. Compared with the fourth embodiment, the steering switching control unit 5' of the eighth embodiment of the present invention includes a resistor 51. ', a capacitor 52', a discharge loop diode 53', a first voltage divider resistor 54', a second voltage divider resistor 55' and a comparator 56'. A signal output terminal formed by the resistor 51' and the capacitor 52' is connected to one of the negative input terminals 562' of the comparator 56'; and a voltage divider is formed by the two voltage dividing resistors 54' and 55'. The output is coupled to one of the positive inputs 561' of the comparator 56'. Thereby, the drive control unit 1 can perform the rotation control of the fan motor 6 corresponding to a discharge voltage.

In summary, the steering switching control unit 2, 2', 3, 3', 4, 4', 5, and 5' of the present invention is only configured by a plurality of analog components to output the forward/reverse switching signal group. And controlling the fan motor 6 to rotate in a predetermined rotation direction for a period of time after starting, and then controlling the fan motor 6 to rotate in a direction opposite to the predetermined rotation direction, which is required to be utilized by the forward and reverse control circuit of the conventional fan. The controller 92 controls the operation of the fan motor 8, and the present invention will have the effect of reducing the cost of circuit setup.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

[this invention]

1. . . Drive control unit

2. . . Steering control unit

twenty one. . . resistance

twenty two. . . capacitance

2'. . . Steering control unit

twenty one'. . . resistance

twenty two'. . . capacitance

3. . . Steering control unit

31. . . resistance

32. . . capacitance

33. . . Discharge loop diode

3’. . . Steering control unit

31’. . . resistance

32’. . . capacitance

33’. . . Discharge loop diode

4. . . Steering control unit

41. . . resistance

42. . . capacitance

43. . . Discharge loop diode

44. . . Transistor switch

4’. . . Steering control unit

41’. . . resistance

42’. . . capacitance

43’. . . Discharge loop diode

44’. . . Transistor switch

5. . . Steering control unit

51. . . resistance

52. . . capacitance

53. . . Discharge loop diode

54. . . First voltage divider resistor

55. . . Second voltage dividing resistor

56. . . Comparators

561. . . Positive input

562. . . Negative input

5’. . . Steering control unit

51’. . . resistance

52’. . . capacitance

53’. . . Discharge loop diode

54’. . . First voltage divider resistor

55’. . . Second voltage dividing resistor

56’. . . Comparators

561’. . . Positive input

562’. . . Negative input

6. . . Fan motor

[customary]

8. . . Fan motor

91. . . Drive unit

92. . . Microcontroller

Figure 1: Schematic diagram of the positive and negative control circuit of the conventional fan.

Fig. 2 is a schematic view showing the forward and reverse control circuit of the fan of the first embodiment of the present invention.

Fig. 3a is a diagram showing the waveform of a charging voltage generated by the steering switching control unit of the first embodiment of the present invention.

Fig. 3b is a schematic diagram showing the waveform of the charging voltage corresponding to the conversion of the driving control unit of the first embodiment of the present invention.

Fig. 4 is a schematic view showing the forward and reverse control circuit of the fan of the second embodiment of the present invention.

Fig. 5 is a schematic view showing the forward and reverse control circuit of the fan of the third embodiment of the present invention.

Figure 6 is a schematic diagram of a forward and reverse control circuit of a fan according to a fourth embodiment of the present invention.

Figure 7 is a schematic diagram of a forward and reverse control circuit of a fan according to a fifth embodiment of the present invention.

Figure 8 is a schematic view showing the forward and reverse control circuit of the fan of the sixth embodiment of the present invention.

Figure 9 is a schematic diagram of a forward and reverse control circuit of a fan according to a seventh embodiment of the present invention.

Fig. 10 is a view showing the forward and reverse control circuit of the fan of the eighth embodiment of the present invention.

1. . . Drive control unit

2. . . Steering control unit

twenty one. . . resistance

twenty two. . . capacitance

6. . . Fan motor

Claims (18)

A forward/reverse control circuit for a fan, comprising: a drive control unit electrically connected to a fan motor; and a steering switching control unit, configured by at least one charge and discharge circuit, the steering switch control unit electrically connecting the drive And a control unit, and the charging and discharging circuit generates a forward/reverse switching signal group, and controls the fan motor to rotate in a predetermined rotation direction for a period of time after starting, and then controls the fan motor to rotate in a direction opposite to the predetermined rotation direction. The forward and reverse control circuit of the fan according to the first aspect of the invention, wherein the steering switching control unit comprises a resistor and a capacitor, the resistor and the capacitor are connected in series to form the charging and discharging circuit, and the resistor and the capacitor The series connection is a signal output, and the signal output is coupled to the drive control unit. The forward and reverse control circuit of the fan according to the second aspect of the patent application, wherein the capacitor is connected in parallel to the drive control unit. The forward/reverse control circuit of the fan according to claim 3, wherein the steering switching control unit further comprises a discharge loop diode, the discharge loop diode being connected in reverse parallel connection. The forward/reverse control circuit of the fan according to the third or fourth aspect of the patent application, wherein the steering switching control unit further comprises a transistor switch electrically connected to the signal output end. The forward and reverse control circuit of the fan according to claim 5, wherein the output end of the transistor switch is connected in parallel to the drive control unit. The positive/negative control circuit of the fan according to claim 5, wherein the transistor switch is an N-type transistor. The forward/reverse control circuit of the fan according to claim 3 or 4, wherein the steering switching control unit further comprises a comparator having a positive input terminal, the resistor and the capacitor being connected to form one The signal output is electrically connected to the positive input. The forward/reverse control circuit of the fan according to claim 8 , wherein the comparator further has a negative input terminal, and the steering switching control unit further comprises a first voltage dividing resistor and a second voltage dividing resistor. The first voltage dividing resistor and the second voltage dividing resistor are connected in series to each other to form a voltage dividing network having a voltage dividing output, and the voltage dividing output end of the voltage dividing network is electrically connected to the negative input end. The forward and reverse control circuit of the fan according to claim 9 , wherein the voltage dividing network is connected between the power supply VCC and the ground. The forward and reverse control circuit of the fan according to the second aspect of the patent application, wherein the resistor is connected in parallel to the drive control unit. The forward/reverse control circuit of the fan according to claim 11, wherein the steering switching control unit further comprises a discharge circuit diode, and the discharge circuit diode is connected in parallel to the resistor. The forward/reverse control circuit of the fan according to claim 11 or 12, wherein the steering switching control unit further comprises a transistor switch electrically connected to the signal output end. The forward and reverse control circuit of the fan according to claim 13 , wherein the output end of the transistor switch is connected in parallel to the drive control unit. The positive/negative control circuit of the fan according to claim 13 , wherein the transistor switch is a P-type transistor. The forward/reverse control circuit of the fan according to claim 11 or 12, wherein the steering switching control unit further comprises a comparator having a negative input terminal, the resistor and the capacitor being connected to form one The signal output is electrically connected to the negative input. The forward and reverse control circuit of the fan according to claim 16 , wherein the comparator further has a positive input terminal, and the steering switching control unit further comprises a first voltage dividing resistor and a second voltage dividing resistor. The first voltage dividing resistor and the second voltage dividing resistor are connected in series to each other to form a voltage dividing network having a voltage dividing output end, and the voltage dividing output end of the voltage dividing network is electrically connected to the positive input end. The forward and reverse control circuit of the fan according to claim 17, wherein the voltage dividing network is connected between the power supply VCC and the ground.