US20130336760A1

US20130336760A1 - Fan control method, fan model identification method, and fan control circuit

Info

Publication number: US20130336760A1
Application number: US13/755,148
Authority: US
Inventors: Hsi-Pin Li; Che-Ting Li; Keng-Wei Shih
Original assignee: Lite On Technology Corp
Current assignee: Lite On Technology Corp
Priority date: 2012-06-18
Filing date: 2013-01-31
Publication date: 2013-12-19
Also published as: CN103511306A

Abstract

A fan control method is to be implemented by a control circuit for controlling a fan coupled thereto. The fan control method includes configuring the control circuit to output a driving signal to the fan such that the fan rotates according to the driving signal, to detect a rotational speed of the fan and to generate a feedback signal corresponding to the rotational speed thus detected, to identify a model of the fan according to the feedback signal thus generated, and to control rotation of the fan according to the model thus identified.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Chinese Patent Application No. 201210201016.X, filed on Jun. 18, 2012.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a control method, more particularly to a fan control method which performs corresponding control according to different models of fans.
2. Description of the Related Art
The shape of an electronic device has developed toward a miniaturized and compact design as electronic technology advances. On the other hand, more heat may be generated as a result of operation of the electronic device. Once the heat is not dissipated timely from the electronic device, an internal temperature of the electronic device may rise because of accumulated heat, and performance of the electronic device may be adversely influenced.
Taking a projector as an example, heat dissipation and temperature control of the projector have always been important concerns. If a light source of the projector is operated in an excessively high temperature environment, the light source may suffer from issues such as failure, color drift, reduced lifespan, etc. Therefore, a fan is usually utilized in the projector for facilitating fast heat dissipation by virtue of airflow resulting from fan rotation. However, one projector model may be designed for use with more than one model of fans. Different rotational speed feedback signals may be obtained in response to the same pulse-width modulation (PWM) input signal, since each model of fans has distinct specifications. Once a fan is disposed in the projector, a model of the fan is not easily identified. Therefore, optimal temperature control may be hard to achieve because of mismatch between a fan control program and the model of the installed fan.
Currently, a method for identifying a model of a fan is to add an ID pin to the fan, such that the model may be identified via the ID pin using a control program. However, this method requires additional hardware cost and increases complexity in manufacturing.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a fan control method which facilitates optimal temperature control.
Accordingly, the fan control method of the present invention is to be implemented by a control circuit for controlling a fan coupled thereto. The fan control method comprises:
(A) configuring the control circuit to output a driving signal to the fan such that the fan rotates according to the driving signal;
(B) configuring the control circuit to detect a rotational speed of the fan and to generate a feedback signal corresponding to the rotational speed thus detected;
(C) configuring the control circuit to identify a model of the fan according to the feedback signal generated in step (B); and
(D) configuring the control circuit to control rotation of the fan according to the model identified in step (C).
Another object of the present invention is to provide a fan model identification method which facilitates identification of a model of a fan.
Accordingly, the fan model identification method of the present invention is to be implemented by a control circuit for identifying a model of a fan coupled thereto. The fan model identification method comprises:
(a) configuring the control circuit to output a driving signal to the fan such that the fan rotates according to the driving signal;
(b) configuring the control circuit to detect a rotational speed of the fan and to generate a feedback signal corresponding to the rotational speed thus detected; and
(c) configuring the control circuit to identify a model of the fan according to the feedback signal generated in step (b).
Yet another object of the present invention is to provide a fan control circuit which does not require an additional ID pin so as to reduce hardware cost while simplifying manufacturing.
Accordingly, the fan control circuit of the present invention is adapted for controlling a fan coupled thereto. The fan control circuit comprises a pulse-width modulation (PWM) module, a detection module and a control module. The pulse-width modulation (PWM) module is to be coupled electrically to the fan, and is configured to output a driving signal to the fan such that the fan rotates according to the driving signal. The detection module is to be coupled electrically to the fan, and is configured to detect a rotational speed of the fan and to generate a feedback signal corresponding to the rotational speed thus detected. The control module is coupled electrically to the PWM module and the detection module, and is configured to identify a model of the fan according to the feedback signal generated by the detection module and to control rotation of the fan according to the model thus identified.
Effects of the present invention reside in that, by detecting the rotational speed of the fan so as to quickly identify the model of the fan, corresponding thermal control algorithms maybe applied according to different models of the fans. In this way, the fan is controllable with required parameters such that an effect of optimal temperature control may be achieved. Further, an additional ID pin is not required for identifying the model of the fan, such that hardware cost is reduced and complexity in manufacturing is simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of a preferred embodiment with reference to the accompanying drawings, of which:

FIG. 1 is a block diagram illustrating a preferred embodiment of a fan control circuit according to the present invention;

FIG. 2 is a flow chart illustrating a preferred embodiment of a fan control method according to the present invention;

FIG. 3 illustrates specification parameters, which are associated with different fan models of fans, stored in a memory module of the preferred embodiment; and

FIG. 4 is a plot illustrating relationship between duty cycles and rotational speeds of two fan models in the preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a fan device 100 is shown to include a fan 10 and a preferred embodiment of a fan control circuit 20 of the present invention that is coupled electrically to the fan 10. In this embodiment, the fan device 100 is to be applied in a micro projector, and utilizes the fan control circuit 20 to detect a rotational speed of the fan 10 and to generate a feedback signal corresponding to the rotational speed thus detected, so as to identify a model (or ID) of the fan 10 for fast setting of initial parameters of the fan 10, such that the fan 10 may have optimal rotational speed and temperature control. Certainly, the fan device 100 is applicable to any electronic device which requires heat dissipation, such as a computer, a video card, etc., and is not limited to the disclosure in this embodiment.
In the preferred embodiment, the control circuit 20 comprises a pulse-width modulation (PWM) module 21, a detection module 23, a control module 22, a memory module 24, and a display module 25. The PWM module 21 is to be coupled electrically to the fan 10, and is configured to output a driving signal to the fan 10 such that the fan 10 rotates according to the driving signal. Specifically, a rotation speed at which the fan 10 rotates is adjusted according to the driving signal. Preferably, the driving signal is a pulse signal having a specific duty cycle.
The detection module 23 is to be coupled electrically to the fan 10, and is configured to detect the rotational speed of the fan 10 and to generate a feedback signal corresponding to the rotational speed thus detected. The control module 22 is coupled electrically to the PWM module 21 and the detection module 23, and is configured to control operations of the various components in the fan control circuit 20. Details of the control method of the control module 22 will be described in the following paragraphs. The memory module 24 is a memory, is coupled electrically to the control module 22, and stores specification parameters of fans and thermal control algorithms. The specification parameters include a plurality of fan models of the fans, and a plurality of rotational speeds corresponding respectively to the fan models (or IDs) of the fans when driven by a signal with the specific duty cycle. The display module 25 is coupled electrically to the control module 22 for providing information relevant to operation of the fan 10.
Referring to FIG. 2 in combination with FIG. 1, a preferred embodiment of a fan control method to be implemented by the fan control circuit 20 according to the present invention is described in the following.
In step S10, the control module 22 is configured to control the PWM module 21 to output the driving signal to the fan 10 such that the fan 10 rotates according to the driving signal. In this embodiment, the driving signal is a pulse signal having a specific duty cycle.
Referring to FIG. 3, in this embodiment, the memory module 24 stores first and second specification parameters, and first and second thermal control algorithms. Each of the first and second specification parameters includes a respective one of first and second fan models (ID1 and ID2), and a plurality of rotational speeds corresponding respectively to the first and second fan models (ID1 and ID2) of the fans 10 when driven by signals of different duty cycles. The first thermal control algorithm corresponds to the first fan model (ID1), and the second thermal control algorithm corresponds to the second fan model (ID2).
FIG. 4 is a plot illustrating relationship between duty cycles and rotational speeds of the first and second fan models (ID1 and ID2). In the plot, a horizontal axis represents the duty cycle of the pulse signal outputted by the PWM module 21, a vertical axis represents the rotational speeds corresponding to the first and second fan models (ID1 and ID2), a curve L1 represents the relationship between the duty cycle and the rotational speed corresponding to the first fan model (ID1), and a curve L2 represents the relationship between the duty cycle and the rotational speed corresponding to the second fan model (ID2). It is evident from the plot that when the pulse signal outputted from the PWM module 21 has the duty cycle of 60%, a maximum difference exists between the rotational speeds of the two models of fans 10 (i.e., the first and second fan models ID1 and ID2). Therefore, in step S10 of this embodiment, the PWM module 21 is controlled to output the pulse signal having the specific duty cycle of 60%, such that different models of the fans 10 are driven to rotate at corresponding rotational speeds having a relatively significant difference therebetween for facilitating identification of the model of the fan 10.
It is noted that the specific duty cycle of the pulse signal is not limited to the duty cycle at which different models of fans 10 operate such that a maximum difference exists between the rotational speeds of the different models of fans 10. In other words, the specific duty cycle of the pulse signal may be selected according to specifications and characteristics of different fans 10, and is not limited to the disclosure in this embodiment.
Referring back to FIG. 2, in combination with FIG. 1 and FIG. 4, after the control module 22 is configured to control the PWM module 21 to output the pulse signal having the specific duty cycle (60%), step S20 is performed.
In step S20, the detection module 23 is configured to detect the rotational speed of the fan 10 and to generate a feedback signal corresponding to the rotational speed thus detected, and then transmit the feedback signal to the control module 22. The feedback signal is associated with the rotational speed at which the fan 10 rotates. When the fan 10 rotates faster, a higher value of the feedback signal is generated, and vice versa.
In step S30, the control module 22 is configured to identify a model of the fan 10 according to the feedback signal generated by the detection module 23. Step S30 includes the following sub-steps.
In step S31, the control module 22 is configured to determine whether the feedback signal corresponds to a first rotational speed range (FG1), wherein when it is determined that the feedback signal corresponds to the first rotational speed range (FG1), the flow proceeds to step S41. Otherwise, when it is determined that the feedback signal does not correspond to the first rotational speed range (FG1), the flow proceeds to Step S32. In this embodiment, the first rotational speed range (FG1) is set to a range, which is the rotational speed plus or minus 15% of the rotational speed that corresponds to the first fan model (ID1) of the fan 10 driven by the pulse signal having the specific duty cycle of 60% and that is stored as the specification parameter in the memory module 24. That is to say, as long as the feedback signal corresponds to the plus or minus 15% range of the rotation speed corresponding to the first fan model (ID1) at the specific duty cycle, the control module 22 is configured to identify the model of the fan 10 as the first fan model (ID1). Subsequently, in step S41, the control module 22 is configured to control rotation of the fan 10 based on the first thermal control algorithm.
In step S32, the control module 22 is configured to determine whether the feedback signal corresponds to a second rotational speed range (FG2), wherein when it is determined that the feedback signal corresponds to the second rotational speed range (FG2), the flow proceeds to step S42. Otherwise, when it is determined that the feedback signal does not correspond to the second rotational speed range (FG2), the flow proceeds to step S50. In this embodiment, the second rotational speed range (FG2) is set to a range, which is the rotational speed plus or minus 15% of the rotational speed that corresponds to the second fan model (ID2) of the fan 10 driven by the pulse signal having the specific duty cycle of 60% and that is stored as the specification parameter in the memory module 24. That is to say, as long as the feedback signal corresponds to the plus or minus 15% range of the rotation speed corresponding to the second fan model (ID2) at the specific duty cycle, the control module 22 is configured to identify the model of the fan 10 as the second fan model (ID2). Subsequently, in step S42, the control module 22 is configured to control rotation of the fan 10 based on the second thermal control algorithm.
It is apparent that, the first and second rotational speed ranges (FG1 and FG2) should not be limited to the plus or minus 15% ranges of the rotational speeds, and may be modified according to different specifications and needs.
Specifically, since a temperature of the micro projector when just started is lower than a final equilibrium temperature thereof on account of heat accumulation, when the control circuit 20 is controlling rotation of the fan 10, an initial rotational speed of the fan 10 is adjusted to a moderate rotational speed (i.e., lower than a rotational speed at the final equilibrium temperature and higher than a lowest rotational speed of the fan 10), such that noise resulting from rotation of the fan 10 may be reduced while fast thermal equilibrium may be achieved in the micro projector.
When the feedback signal does not correspond to the first and second rotational speed ranges (FG1 and FG2), step S50 is performed. In step S50, the control module 22 is configured to control the display module 25 to provide an error notification, so as to inform users that the model of the fan 10 is unidentifiable.
Since the rotational speed of the fan 10 will be different depending on the model of the fan 10 when the fan 10 is driven by the pulse signal with the specific duty cycle, by means of the control circuit 20 of the present invention, the model of the fan 10 may be quickly identified, without requiring an additional ID pin for the fan 10. Moreover, the control circuit 20 is configured to control rotation of different models of the fans based on corresponding thermal control algorithms, and corresponding control parameters may be easily applied to the fan 10 so as to achieve optimal temperature control.
To sum up, by detecting the rotational speed of the fan 10 so as to identify the model of the fan 10, an ID pin of the fan 10 may be omitted so as to reduce the hardware cost and simplify the manufacturing procedure. Moreover, corresponding thermal control algorithms may be quickly applied to the fan 10 according to different fan models, so as to satisfy the need of heat dissipation in micro projectors and the like.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.

Claims

What is claimed is:

1. A fan control method that is to be implemented by a control circuit for controlling a fan coupled thereto, the fan control method comprising:

(A) configuring the control circuit to output a driving signal to the fan such that the fan rotates according to the driving signal;

(B) configuring the control circuit to detect a rotational speed of the fan and to generate a feedback signal corresponding to the rotational speed thus detected;

(C) configuring the control circuit to identify a model of the fan according to the feedback signal generated in step (B); and

(D) configuring the control circuit to control rotation of the fan according to the model identified in step (C).

2. The fan control method as claimed in claim 1, wherein, in step (A), the driving signal is a pulse signal having a specific duty cycle.

3. The fan control method as claimed in claim 2, the control circuit including a memory module which stores a plurality of fan models of fans and a plurality of rotational speeds corresponding respectively to the fan models of the fans when driven by a signal with the specific duty cycle,

wherein, in step (C), the control circuit is configured to compare the feedback signal with the rotational speeds stored in the memory module so as to identify the model of the fan.

4. The fan control method as claimed in claim 3, each of the plurality of the fan models corresponding to a rotational speed range which is associated with the respective one of the plurality of the rotational speeds,

wherein, in step (C), the control circuit is configured to determine whether the feedback signal corresponds to one of the rotational speed ranges, and to identify the model of the fan as the fan model which corresponds to said one of the rotational speed ranges when it is determined that the feedback signal corresponds to said one of the rotational speed ranges.

5. The fan control method as claimed in claim 4, the memory module storing first and second fan models, a first rotational speed range and a second rotational speed range which correspond respectively to the first and second fan models, and a first thermal control algorithm and a second thermal control algorithm which correspond respectively to the first and second rotational speed ranges,

wherein step (C) includes the following sub-steps of:

(C-1) configuring the control circuit to determine whether the feedback signal corresponds to the first rotational speed range, wherein

when it is determined that the feedback signal corresponds to the first rotational speed range, the control circuit is configured to control rotation of the fan based on the first thermal control algorithm in step (D), and

when it is determined that the feedback signal does not correspond to the first rotational speed range, the flow proceeds to sub-step (C-2); and

(C-2) configuring the control circuit to determine whether the feedback signal corresponds to the second rotational speed range, wherein

when it is determined that the feedback signal corresponds to the second rotational speed range, the control circuit is configured to control rotation of the fan based on the second thermal control algorithm in step (D), and

when it is determined that the feedback signal does not correspond to the second rotational speed range, the control circuit is configured to provide an error notification.

6. The fan control method as claimed in claim 2, the control circuit storing a plurality of fan models of fans and a plurality of thermal control algorithms which correspond respectively to the fan models, wherein:

in step (C), one of the fan models is identified as the model of the fan; and

in step (D), the rotation of the fan is controlled according to one of the thermal control algorithms that corresponds to said one of the fan models identified in step (C).

7. The fan control method as claimed in claim 3, wherein the specific duty cycle is a duty cycle at which two models of fans operate such that a maximum difference exists between the rotational speeds of the two models of fans.

8. A fan model identification method that is to be implemented by a control circuit for identifying a model of a fan coupled thereto, the fan model identification method comprising:

(b) configuring the control circuit to detect a rotational speed of the fan and to generate a feedback signal corresponding to the rotational speed thus detected; and

(c) configuring the control circuit to identify a model of the fan according to the feedback signal generated in step (b).

9. The fan model identification method as claimed in claim 8, wherein, in step (a), the driving signal is a pulse signal having a specific duty cycle.

10. The fan model identification method as claimed in claim 9, the control circuit including a memory module which stores a plurality of fan models of fans and a plurality of rotational speeds corresponding respectively to the fan models of the fans when driven by a signal with the specific duty cycle,

11. The fan model identification method as claimed in claim 10, each of the plurality of the fan models corresponding to a rotational speed range which is associated with the respective one of the plurality of the rotational speeds,

12. A fan control circuit adapted for controlling a fan coupled thereto, said fan control circuit comprising:

a pulse-width modulation (PWM) module to be coupled electrically to the fan, and configured to output a driving signal to the fan such that the fan rotates according to the driving signal;

a detection module to be coupled electrically to the fan, and configured to detect a rotational speed of the fan and to generate a feedback signal corresponding to the rotational speed thus detected; and

a control module coupled electrically to said PWM module and said detection module, and configured to identify a model of the fan according to the feedback signal generated by said detection module and to control rotation of the fan according to the model thus identified.

13. The fan control circuit as claimed in claim 12, wherein the driving signal is a pulse signal having a specific duty cycle.

14. The fan control circuit as claimed in claim 13, further comprising a memory module which is coupled electrically to said control module and which stores a plurality of fan models of fans and a plurality of rotational speeds corresponding respectively to the fan models of the fans when driven by a signal with the specific duty cycle, wherein:

said control module is configured to compare the feedback signal with the rotational speeds stored in said memory module so as to identify the model of the fan.

15. The fan control circuit as claimed in claim 14,

wherein each of the plurality of the fan models corresponds to a rotational speed range which is associated with the respective one of the plurality of the rotational speeds;

wherein said control module is configured to determine whether the feedback signal corresponds to one of the rotational speed ranges, and to identify the model of the fan as the fan model which corresponds to said one of the rotational speed ranges when it is determined that the feedback signal corresponds to said one of the rotational speed ranges.

16. The fan control circuit as claimed in claim 15, further comprising a display module coupled electrically to said control module, said memory module storing first and second fan models, a first rotational speed range and a second rotational speed range which correspond respectively to the first and second fan models, and a first thermal control algorithm and a second thermal control algorithm which correspond respectively to the first and second rotational speed ranges,

wherein said control module is configured to determine whether the feedback signal corresponds to the first rotational speed range, wherein

when it is determined that the feedback signal corresponds to the first rotational speed range, said control module is configured to control rotation of the fan based on the first thermal control algorithm, and

when it is determined that the feedback signal does not correspond to the first rotational speed range, said control module is configured to determine whether the feedback signal corresponds to the second rotational speed range, wherein

when it is determined that the feedback signal corresponds to the second rotational speed range, said control module is configured to control rotation of the fan based on the second thermal control algorithm, and

when it is determined that the feedback signal does not correspond to the second rotational speed range, the control module is configured to control said display module to provide an error notification.

17. The fan control circuit as claimed in claim 13, further comprising a memory module which is coupled electrically to said control module and which stores a plurality of fan models of fans and a plurality of thermal control algorithms which correspond respectively to the fan models, wherein:

when one of the fan models is identified as the model of the fan, said control module is configured to control the rotation of the fan according to one of the thermal control algorithms that corresponds to said one of the fan models thus identified.