U.S. patent application number 11/075947 was filed with the patent office on 2005-11-24 for fan speed control system.
This patent application is currently assigned to Delta Electronics, Inc.. Invention is credited to Chang, Sans, Chiu, Chun-Lung, Chiu, Magellan, Tsai, Ming-Shi.
Application Number | 20050257537 11/075947 |
Document ID | / |
Family ID | 35373868 |
Filed Date | 2005-11-24 |
United States Patent
Application |
20050257537 |
Kind Code |
A1 |
Chang, Sans ; et
al. |
November 24, 2005 |
Fan speed control system
Abstract
A fan speed control system. A temperature and humidity sensing
unit detects environmental temperature and humidity and outputs a
corresponding electrical signal. A micro-control unit receives and
processes the electrical signal to obtain a digital signal, and
sends the digital signal to the fan motor circuit to control fan
speed accordingly.
Inventors: |
Chang, Sans; (Taoyuan Hsien,
TW) ; Chiu, Magellan; (Taoyuan Hsien, TW) ;
Chiu, Chun-Lung; (Taoyuan Hsien, TW) ; Tsai,
Ming-Shi; (Taoyuan Hsien, TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Delta Electronics, Inc.
|
Family ID: |
35373868 |
Appl. No.: |
11/075947 |
Filed: |
March 10, 2005 |
Current U.S.
Class: |
62/176.6 ;
236/44C; 236/49.3; 62/178 |
Current CPC
Class: |
F24F 2110/10 20180101;
F25B 2600/112 20130101; F24F 11/30 20180101; F24F 11/77 20180101;
F24F 2110/20 20180101; F25B 2700/02 20130101; Y02B 30/70
20130101 |
Class at
Publication: |
062/176.6 ;
062/178; 236/044.00C; 236/049.3 |
International
Class: |
F24F 007/00; F25D
017/04; F25B 049/00; F25D 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2004 |
TW |
93113916 |
Claims
What is claimed is:
1. A fan speed control system, comprising: a fan motor circuit; a
temperature sensing element detecting environmental temperature and
sending a corresponding first electrical signal; a humidity sensing
element detecting environmental humidity and sending a
corresponding second electrical signal; and a micro-control unit
receiving and processing the first and second electrical signals to
obtain a digital signal, and sending the digital signal to the fan
motor circuit to control fan speed.
2. The fan speed control system as claimed in claim 1, further
comprising a speed sensing unit detecting the fan speed and sending
a corresponding third electrical signal to the micro-control
unit.
3. The fan speed control system as claimed in claim 1, wherein the
humidity sensing element comprises a humidity-sensitive
resistor.
4. The fan speed control system as claimed in claim 1, wherein the
temperature sensing element comprises a heat-sensitive
resistor.
5. The fan speed control system as claimed in claim 1, wherein the
digital signal comprises a pulse width modulation (PWM) signal.
6. A fan speed control system, comprising: a fan motor circuit; a
temperature and humidity sensing unit detecting environmental
temperature and humidity and sending a corresponding first
electrical signal; and a micro-control unit receiving and
processing the first electrical signal to obtain a digital signal,
and sending the digital signal to the fan motor circuit to control
fan speed.
7. The fan speed control system as claimed in claim 6, further
comprising a speed sensing unit detecting the fan speed and sending
a corresponding second electrical signal to the micro-control
unit.
8. The fan speed control system as claimed in claim 6, wherein the
temperature and humidity sensing unit comprises a heat-sensitive
element, a humidity-sensitive element, and a plurality of
resistors.
9. The fan speed control system as claimed in claim 8, wherein the
heat-sensitive element and the humidity-sensitive element both
comprise resistors.
10. The fan speed control system as claimed in claim 6, wherein the
digital signal comprises a pulse width modulation (PWM) signal.
Description
BACKGROUND
[0001] The present invention relates to a speed control system for
fan, and particularly to a speed control system for fan responding
to environmental temperature and humidity.
[0002] Fans are widely used for heat dissipation in electrical
devices. Generally, fan speed is modulated by a speed control
circuit responding to environmental temperature. The speed control
circuit is typically driven by pulse width modulation (PWM) signals
or voltages. Humidity, however, is not considered a factor in
modulation of fan speed in the speed control circuit. When an
electrical device with the speed control circuit is operated in low
environmental temperature and high humidity, fan speed is not
increased due to the low temperature. However, moisture may adhere
to elements of the fan and the electrical device, resulting in
short-circuit or rust that contaminates or damages the electrical
device.
SUMMARY
[0003] Accordingly, an embodiment of a fan speed control system
comprises a fan motor circuit, a temperature and humidity sensing
unit, and a micro-control unit. The temperature and humidity
sensing unit sends an electrical signal related to detected
temperature and humidity. The micro-control unit receives and
processes the electrical signal to obtain a digital signal, and
sends the digital signal to the fan motor circuit to control speed
thereof.
[0004] The temperature and humidity sensing unit can comprise
heat-sensitive and humidity-sensitive resistors, and the digital
signal can comprise a pulse width modulation (PWM) signal.
[0005] A detailed description is given in the following embodiments
with reference to the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
[0006] The present invention can be more fully understood by
reading the subsequent detailed description and examples with
references made to the accompanying drawings, wherein:
[0007] FIG. 1 is a block diagram of a fan speed control system of
an embodiment of the invention; and
[0008] FIG. 2 is a schematic view of the temperature and humidity
sensing unit in an embodiment of the present invention.
DETAILED DESCRIPTION
[0009] In an embodiment of the invention, a fan speed control
system responding to environmental temperature and humidity is
provided in an electrical device. In some embodiments, moisture can
be prevented from contacting elements of the electrical device and
the fan thereof.
[0010] FIG. 1 is a block diagram of an embodiment of a fan speed
control system 2, comprising a temperature and humidity sensing
unit 21, a micro-control unit (MCU) 22, and a fan motor circuit
23.
[0011] The temperature and humidity sensing unit 21 detects
temperature T and humidity H in the operating environment, and
sends an accordingly generated electrical signal S.sub.1 to MCU 22
comprising one electrical signal for temperature T, and one for
humidity H. The MCU 22 receives and processes the electrical signal
S.sub.1 to obtain a digital signal 221, such as a pulse width
modulation (PWM) signal, and sends the digital signal 221 to the
fan motor circuit 23 to control fan speed V.
[0012] Further, the fan speed control system in the embodiment
comprises a speed sensing unit 24, which detects fan speed V and
sends an electrical signal S.sub.2 therefore to the MCU 22, which
compensates digital signal 221 accordingly. Thus, fan speed V
achieves a desired value with the feedback control of the
electrical signal S.sub.2.
[0013] FIG. 2 shows the temperature and humidity sensing unit 21,
comprising a temperature sensing element 211, a humidity sensing
element 212, and resistors 213 and 214. The temperature sensing
element 211 can be a heat-sensitive resistor, and the humidity
sensing element 212 can be a humidity-sensitive resistor.
[0014] The temperature and humidity sensing unit 21 further
comprises a voltage input terminal 215 and two signal output
terminals 216. The voltage input terminal 215 is connected to a
power source V.sub.in, and the signal output terminals 216 are
connected to the MCU 22.
[0015] The signal output terminals 216 transfer electrical signals
S11 and S12 from the temperature sensing element 211 and the
humidity sensing element 212. The signal output terminals 216
obtain terminal voltages from the heat-sensitive resistor of the
temperature sensing element 211 and the humidity-sensitive resistor
of the humidity sensing element 212 as electrical signals S11 and
S12. Resistance R1 of resistor 213 and resistance R2 of resistor
214 can be modulated in accordance with the resistances of the
heat-sensitive resistor and the humidity-sensitive resistor.
[0016] According to the embodiment, the speed control system 2
controls fan speed V of the fan according to environmental
temperature and humidity. Embodiments of the invention may thus
contribute to prevention of overheating and condensation.
[0017] While the invention has been described by way of example and
in terms of preferred embodiment, it is to be understood that the
invention is not limited thereto. To the contrary, it is intended
to cover various modifications and similar arrangements (as would
be apparent to those skilled in the art). Therefore, the scope of
the appended claims should be accorded the broadest interpretation
so as to encompass all such modifications and similar
arrangements.
* * * * *