JP2002221187A - Fan-monitoring control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give an alarm by detecting the number of revolutions of a fan, simultaneously to rotate the fan only when a unit of a cooling object is in a mounted state, by a simple circuit and with a simple structure. SOLUTION: A fan-monitoring control circuit is constituted of a half mirror 32 to pass emission light from a light emitting diode 31 between vanes of the fan 2 and simultaneously to permeate reflected light from the unit to return on the same optic axis, a photo diode 33 to receive the reflected light, a mounted detector 35 to detect the mounted state of the unit 1 from the reflected light and to output a mounted detection signal 102, a revolution number detector 36 to give the alarm by detecting the number of revolutions of the fan 2 from an interruption period of the reflected light, a switch 38 to switch on an electric power source of the fan 2 by an alarm circuit 37 and the mounted detection signal 102, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blower monitoring and control circuit, and more particularly to a blower monitoring and control circuit for detecting a rotation speed and generating an alarm.

[0002]

2. Description of the Related Art In general, a light emitting diode and a photodiode are combined to detect the number of rotations, and a rotating body intermittently emits light emitted from the light emitting diode, and the intermittent light is received by the photodiode. In many cases, the number of rotations is detected. For example, there is a prior art described in Japanese Patent Application Laid-Open No. 57-72064.

FIG. 4 is a block diagram showing this prior art.
The present embodiment relates to a speed and rotation number detecting device for detecting the rotation speed of a rotating disk attached to an axle in order to measure the speed of a vehicle.

FIG. 4A is a side view of a speed and rotation number detecting device, and FIG. 4B is a front view of a rotating disk. The rotating shaft 41 rotates in proportion to the speed of the axle as the object to be measured. The rotating disk 42 is attached to the rotating shaft 41, and has a plurality of slits (2a) to (2n) on the same circumference around the rotating shaft 41. The light emitting device 43 is installed on one surface side of the rotating disk 42 and has a slit (2a).
To project light to (2n), and is composed of a light emitting diode 431, a variable resistor 432 connected in series to the light emitting diode 431, and a lens 433 for taking out the light emitted from the light emitting diode 431 as a parallel light beam. .

The DC power supply 44 applies a DC voltage to the light emitting diode 431 via the variable resistor 432.
The light receiving device 45 is provided on the other surface side of the rotating disk 42.
, Which receives the light from the light emitting device 43 passing through the slits (2a) to (2n), and which collects the light from the light emitting device 43;
1, a photodiode 452 that receives light through the photodiode 1 and generates an output in accordance with the amount of received light, and the photodiode 452 is connected between the collector and the base.
And an output transistor 453 for amplifying the output of the second transistor. The output terminals 46a and 46b are connected to the collector and the emitter of the output transistor 453.

Next, this operation will be described. Since the rotating shaft (1) rotates in proportion to the vehicle speed, the rotating disk 42 also rotates in proportion to the vehicle speed. Therefore, the light from the light emitting device 43 is intermittently received by the light receiving device 45 via the slits (2a) to (2n) at a cycle proportional to the vehicle speed. Therefore, output pulses having a frequency proportional to the vehicle speed are obtained at the output terminals 46a and 46b. In this case, the rotating shaft 4
The number of rotations of 1 can be similarly detected from the frequency of the output pulses of the output terminals 46a and 46b.

Another conventional example for detecting the number of revolutions is disclosed in Japanese Patent Application Laid-Open No. 62-290334 (not shown). This conventional example is similar to the conventional example described with reference to FIG. 4, but is different in that emitted light from a light emitting diode is reflected by a rotating unit, and the reflected light is received to detect the number of rotations.

That is, in this conventional example, the number of rotations of the rotor of the flat motor is detected. The number of rotations detecting pattern is composed of a reflection pattern and an absorption pattern provided radially and alternately on a rotating part. A slit plate having a radial slit provided opposite to the rotation speed detection pattern,
A light detector having a light-emitting element and a light-receiving element provided in close proximity to the rotation speed detection pattern via the slit plate, and a light emitted from the light-emitting element is provided to the rotation unit through the slit. The light reflected by the reflection pattern is received by the light receiving element to detect the number of rotations.

[0009]

The prior art for detecting the number of revolutions can be applied to the detection of the number of revolutions of a blower. In the case of a blower, the purpose of detecting the number of revolutions is used for monitoring, for example, when a decrease in the number of rotations is determined to be abnormal and an alarm is generated. However, when this conventional technique is applied to a blower, there are the following problems.

First, in the case of a blower, an object to be cooled, for example, in the case of a communication device, the unit is not fixedly mounted, but in a plug-in system, there are mounted and unmounted states. It is a unit in a mounted state that needs to be installed. When the unit is not mounted, it is desirable to stop the blower and place it in terms of power saving, noise, and the like. In order to perform this control automatically, it is necessary to detect whether the unit is mounted or not, and control the power of the blower to be turned on and off based on the result. There is a problem that such a control function is not included in the related art.

Second, in the conventional example described with reference to FIG.
Since the light-emitting diode and the photodiode are arranged on the left and right sides of the rotating disk, if this is applied to a blower, one of them will be provided on the side of the object to be cooled, which receives cooling air. Therefore, there is a problem that it is not desirable and the structure becomes complicated.

Third, in the latter conventional example, it is necessary to provide a reflection pattern on the rotating portion. When applied to a blower, providing the reflection pattern on the blade of the blower is sufficient when the blade surface is a curved surface. There is a problem that light cannot be obtained.

[0013]

According to the present invention, there is provided a blower monitoring and control circuit, wherein a light emitting source is disposed behind a blower for cooling a unit, and light emitted from the light emitting source passes between blades of the blower and is reflected by the unit. When the received light level is higher than a predetermined reference value, a detection signal indicating that the unit is in a mounted state is output, and the power of the blower is turned on by the detection signal.

A means is provided for detecting the number of rotations of the blower from the number of intermittent times of the reflected light intermittently due to the rotation of the blower, and generating an alarm when the number of rotations falls below a predetermined reference value. May be.

Further, there may be provided means for causing the light emitting source to emit light intermittently at a predetermined cycle when the detection signal is not output.

The light emitting diode provided behind the blower for cooling the unit and the light emitted from the light emitting diode pass between the blades of the blower and are reflected toward the unit at the same time as the light reflected from the unit is reflected by the same unit. A half mirror that transmits the reflected light returning on the optical axis, a photodiode that receives the transmitted light of the half mirror and converts the light into a current, a voltage converter that converts a current output from the photodiode into a voltage, and the voltage A mounting detector that compares a voltage output from the converter with a predetermined reference voltage and outputs a mounting detection signal indicating that the unit is in a mounting state when the voltage is higher than the reference voltage; and a power supply of the blower based on the mounting detection signal. And a power switch for turning on.

A voltage detector which receives a voltage output from the voltage converter and counts the number of times the voltage is interrupted when the voltage is interrupted by the rotation of the blower to detect the number of revolutions; May be provided with an alarm circuit for generating an alarm when the output value falls below the reference value.

[0018] Further, there is provided a light emitting diode controller for intermittently turning on and off a driving power supply of the light emitting diode at a predetermined cycle when the mounting detector does not output the mounting signal, that is, when the unit is not mounted. You may do it.

Also, instead of the half mirror, the emitted light passes between the blades of the blower and is reflected to the unit, and is reflected such that the optical axis of the reflected light is aligned with the optical axis of the emitted light. A reflection mirror may be provided, and the photodiode may directly receive light reflected by the reflection mirror.

Further, the mounting detector may be configured to change the reference voltage and the alarm circuit can change the reference value.

[0021]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is a block diagram showing a second embodiment of the present invention, and FIG. 3 explains the operation of the blower monitoring control circuit in FIG. 2 and FIG. FIG.

In FIG. 1, a unit 1 for an object to be cooled, which is a part of a communication device, a blower 2 provided below the unit 1 for cooling the unit, and a blower monitoring control circuit of the present invention for monitoring and controlling the blower 1 3 as a whole.

The blower monitoring and control circuit 3 includes a light emitting diode 31 provided behind the blower 2 for cooling the unit.
A half mirror 32 that transmits the light emitted from the light emitting diode 31 through the blades of the blower 2 and reflects the light toward the unit 1 while reflecting the light reflected by the unit 1 and returning on the same optical axis; 32, a photodiode 33 for receiving the transmitted light and converting the current into a current, a voltage converter 34 for converting the current output from the photodiode 33 to a voltage 101, and a voltage 101 output from the voltage converter 34 as a predetermined reference voltage. If the comparison result is higher than this reference voltage, the mounting detection signal 10 indicating that the unit 1 is in the mounting state.
2, a power switch 38 for turning on the power of the blower 2 based on the mounting detection signal 102, and a voltage 101 output from the voltage converter. When this voltage is interrupted by the rotation of the blower 2, It comprises a rotation speed detector 36 for counting the number of intermittent operations and detecting the rotation speed, and an alarm circuit 37 for generating an alarm when the output value 103 of the rotation speed detector 36 falls below a reference value.

Next, the operation will be described with reference to FIG. 1 and FIG. In FIG. 1, the light emitted from the light emitting diode 31 is condensed by an internal lens to form a beam,
2, half of the light amount is reflected in the unit direction. The reflected emission light passes between the blades of the blower 2 which is stopped, is reflected by the reflection plate 11 of the unit 1, returns on the return path having the same optical axis as the outward path, and transmits half of the light amount through the half mirror 32. The light is received by the photodiode 33.

The photodiode 33 condenses the received light by an internal lens, converts the light into a current by the photodiode, and outputs the current. The voltage converter 34 power-amplifies this current, converts it into a voltage 101, and outputs it. The voltage 101 is the mounting detector 3
5 and the rotation speed detector 36, and the mounting detector 35 compares the voltage 101 with an internal reference voltage, and outputs a mounting detection signal 102 when the voltage is equal to or higher than the reference voltage. The mounting detection signal 102 is input to a switch 38, which is turned on to supply power to the blower 2. Then, the blower 2 starts rotating.

On the other hand, the rotation speed detector 36 is interrupted by the voltage 101 due to the rotation of the blower 2, so the number of interruptions is counted by an internal counter to measure the rotation speed of the blower 2, and the measured value 103 is output. . And the alarm circuit 37
Compares the measured value with the reference value held therein, generates a drop detection signal when the measured value is lower than the reference value, and further takes the logical product of the drop detection signal and the mounting detection signal 102, and then calculates Is output to the outside as an alarm signal and an alarm is displayed at the same time.

When the blower 2 starts rotating, the emitted light from the half mirror 32 impinges on the blades of the blower 2, which becomes scattered light. Since it is slight and has a sufficient level difference from the reflected light from the unit, it is possible to identify the intermittent of the reflected light from the unit 1.

Next, the above operation will be supplemented with reference to FIG. First, when the unit 1 is not mounted, the voltage 101
Is approximately OV, and when the unit 1 is mounted, the voltage 101 becomes EV and a mounting detection signal 102 is output. This causes the blower 2 to start rotating, so that the voltage 101 has an intermittent waveform as shown. At this time, the lower limit of the voltage 101 does not become OV due to the scattered light hitting the blade 1 of the blower. In this normal state, when the unit 1 is pulled out, the voltage 101 does not become OV due to scattered light, but is lower than the reference voltage. Therefore, the transmission of the mounting detection signal 102 is stopped. Stops.

When the unit is mounted again, the mounting detection signal 102 is output and the blower 2 starts rotating. Further, if the blower 2 fails in this state and the number of rotations decreases, an alarm is generated from the alarm circuit 37.

Next, a second embodiment of the present invention will be described with reference to FIG. The difference from the case of FIG. 1 is that when the mounting detector 35 does not output the mounting signal 102, that is, when the unit 1 is not mounted, the driving power supply of the light emitting diode 31 is intermittently turned on and off at a predetermined cycle. A light emitting diode controller 39 is provided. The other parts are the same as those in FIG.

When the unit 1 is not mounted and the blower 2 is stopped, that is, when the mounting detection signal 102 is off, the light emitting diode controller 39 turns off the power of the light emitting diode 39 by one.
The light emitting diode 31 is intermittently turned on for only one second every minute, and the light emitting diode 31 emits emitted light intermittently for one second.
When the first reflected light of the emitted light from the light emitting diode 31 is received by the photodiode 33 by mounting the unit 1, a mounting detection signal 102 is output, and the light emitting diode controller 39 continuously switches the power supply of the light emitting diode 31. To supply. By such control of the light emitting diode controller 39, the power consumption of the light emitting diode at the time of standby for mounting the unit can be reduced.

Instead of the half mirror 32, a normal reflection in which the emitted light passes between the blades of the blower 2 and is reflected to the unit 1 and is reflected so that the optical axis of the reflected light is shifted from the optical axis of the emitted light. This may be done if a mirror (not shown) is provided and the photodiode 33 can be arranged so as to directly receive the reflected light. In this way, an inexpensive reflection mirror can be used.

Further, if the reference voltage of the mounting detector 35 and the reference value of the alarm circuit 37 are made variable, it is possible to set the optimum identification sensitivity according to the environmental conditions.

[0034]

As described above, the blower monitoring and control circuit of the present invention detects the mounting / non-mounting of the unit and detects the rotation speed of the blower from the reflected light that passes between the blades of the blower, is reflected by the unit and returns on the outward path. Since the detection is performed simultaneously, when the unit is not mounted, the rotation of the blower can be automatically stopped to save power and reduce noise.Also, when the rotation of the blower decreases, an alarm is generated and maintenance is performed. This has the effect of making the flight easier. Further, there is an effect that these two functions can be realized by a simple circuit and structure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a characteristic diagram for explaining the operation in FIGS. 1 and 2;

4A is a side view of a conventional example, and FIG. 4B is a side view of a rotating plate.

[Explanation of symbols]

 Reference Signs List 1 unit 2 blower 3 blower monitoring control circuit 31 light emitting diode 32 half mirror 33 photodiode 34 voltage converter 35 mounting detector 36 rotation speed detector 37 alarm circuit 38 switch 39 light emitting diode controller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02P 5/00 H02P 5/00 T H05K 7/20 H05K 7/20 J F-term (Reference) 3H021 AA01 BA01 BA11 BA12 BA16 BA21 CA00 CA04 CA07 EA05 EA07 EA08 EA20 3H045 AA06 AA09 AA12 AA26 BA01 BA31 BA32 BA38 BA41 CA00 CA09 CA21 EA17 EA22 EA34 EA50 5E322 BB04 5F089 BB03 BC02 CA21 FA06 GA01 MM03 GG01 MM01

Claims (9)

[Claims] 1. A light emitting source is placed behind a blower for cooling a unit, and light emitted from the light emitting source passes through the blades of the blower and receives reflected light reflected by the unit. A blower monitoring and control circuit, comprising: means for outputting a detection signal indicating that the unit is in a mounted state when the value is higher than a reference value, and turning on the power of the blower in accordance with the detection signal. 2. A means for detecting the number of revolutions of the blower from the number of intermittent times of the reflected light intermittently due to the rotation of the blower, and generating an alarm when the number of revolutions falls below a predetermined reference value. The blower monitoring and control circuit according to claim 1, wherein: 3. The blower monitoring and control circuit according to claim 1, further comprising means for intermittently emitting light from said light emitting source at a predetermined cycle when said detection signal is not output. 4. A light emitting diode provided behind a blower for cooling the unit, and the light emitted from the light emitting diode passes between the blades of the blower and is reflected in the unit direction, and is simultaneously reflected by the unit and reflected by the unit. A half mirror that transmits the reflected light returning on the optical axis, a photodiode that receives the transmitted light of the half mirror and converts the light into a current, a voltage converter that converts a current output from the photodiode into a voltage, and the voltage A mounting detector that compares a voltage output from the converter with a predetermined reference voltage and outputs a mounting detection signal indicating that the unit is in a mounting state when the voltage is higher than the reference voltage; and a power supply of the blower based on the mounting detection signal. And a power switch for turning on the fan. 5. A rotation number detector for inputting a voltage output from the voltage converter and counting the number of interruptions and detecting the rotation number when the voltage is interrupted by the rotation of the blower, and a rotation number detector. 5. The blower monitoring and control circuit according to claim 4, further comprising: an alarm circuit for generating an alarm when an output value of said blower falls below a reference value. 6. A light emitting diode controller for intermittently turning on and off a driving power supply of the light emitting diode at a predetermined cycle when the mounting detector does not output the mounting signal, that is, when the unit is not mounted. The blower monitoring and control circuit according to claim 4 or 5, wherein 7. Instead of the half mirror, the emitted light passes between the blades of the blower and is reflected to the unit, and is reflected so that the optical axis of the reflected light is aligned with the optical axis of the emitted light. 7. The blower monitoring and control circuit according to claim 4, further comprising a reflection mirror, wherein the photodiode directly receives light reflected by the reflection mirror. 8. The blower monitoring and control circuit according to claim 4, wherein the mounting detector is capable of changing the reference voltage. 9. The blower monitoring control circuit according to claim 5, wherein said alarm circuit is capable of changing said reference value.