JP2007206110A - Dustproof filter clog detection device and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a conventional system, wherein when a filter becomes clogged, the temperature in a ventilation duct increases, and thus a difference between the outside temperature and inside temperature is detected to determine, based on a fixed threshold, whether the filter has been clogged, in which case the increase in temperature difference is small and a temperature detecting circuit fluctuates, which make it difficult to detect the difference and is likely to cause malfunctions, and the consideration, for effective detection in the system of cooling two or more heat generating bodies, is not taken. <P>SOLUTION: A control device, using two or more fans, adopts the system in which the filter also serves as the ventilation duct. In this system, a temperature detection circuit is disposed on the side of a low-pressure control fan in the duct, because the current of air in the duct is drawn by a higher-pressure control fan, when the filter is clogged. Since with this configuration the difference between the outside air temperature and the inside air temperature is increased, to immediate detection of the clogging of the dustproof filter becomes possible. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device that air-cools a heat source using wind passing through a dustproof filter, and more particularly to a clogging detection device that detects clogging of a dustproof filter.

  In Patent Document 1 below, the internal temperature and the external temperature of the apparatus are detected, the temperature difference between the internal temperature and the external temperature is obtained, it is determined whether the temperature difference is within the normal temperature difference, Determine mouth (including filter) or fan abnormality. And when the rotation speed of a fan is normal, the technique which determines with it being the state (clogging) with which the air supply / exhaust port was block | closed is disclosed.

  Patent Document 2 below discloses a technique for determining clogging of a filter based on a rotation signal corresponding to the rotation speed of a fan.

JP 2002-357317 A JP 2002-62589 A

  In Patent Documents 1 and 2, when there are a plurality of heating elements (components) having different allowable temperatures in the housing, specifically, for example, a heating element (component) such as a light source having a high allowable temperature and the allowable temperature are low. An effective clogging detection technique when there is a heating element (component) of a display element (for example, a liquid crystal panel) is not considered.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dustproof unit for cooling at least two heating elements (heat sources) having different allowable temperatures using fans having different cooling capacities. It is an object of the present invention to provide a dustproof filter clogging detection device capable of increasing the temperature difference between the outside air and the ventilation duct when the filter is clogged, reducing the malfunction of the dustproof filter clogging detection, and reducing the cost.

  One aspect of the present invention is a detection device that detects clogging of a dustproof filter provided on any one of an upper surface, a lower surface, and a side surface of a housing, and includes at least first and second heating elements, and the dustproof filter. A first fan that cools the first heating element by sucking wind from the air and a second fan that cools the second heating element by sucking wind from the dustproof filter, and the rotational speed is different from that of the first fan. A duct having a second fan, a split section that divides the wind from the dust-proof filter from a predetermined location into a portion leading to the first fan and a portion leading to the second fan; And a first temperature detector disposed outside the device, a temperature inside the device, a second temperature detector disposed in the device, and the first temperature. The temperature detected by the detection unit and the temperature detected by the second temperature detection unit It detects a difference temperature between the temperature, the difference temperature and a determining controller whether within a predetermined threshold.

  ADVANTAGE OF THE INVENTION According to this invention, the malfunctioning of clogging detection of a dustproof filter can be reduced. In addition, since the temperature detection circuit for detecting the internal temperature in the ventilation duct can be integrated into one, the cost can be reduced.

  Hereinafter, embodiments of the present invention will be described.

  A clogging detection device for a dustproof filter according to a first embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating a clogging detection device for a dustproof filter according to a first embodiment, FIG. 2 is a diagram illustrating a relationship between a detection temperature and a clogging rate in the first embodiment, and FIG. It is a flowchart of a process.

  In the following description, a device having a heating element is assumed to be a liquid crystal projector, and the heating elements are classified into two groups for the sake of convenience for ease of explanation (however, the first embodiment is not limited to this). And may have a plurality of groups). One is a group of heating elements having a high allowable temperature, such as PBS, and the other is a group of heating elements having a low allowable temperature, such as a display element and a polarizing plate.

  In FIG. 1, the 1st heat generating body 21 with high allowable temperature is PBS, for example. Here, only the first heating element 21 is shown as a heating element with a high allowable temperature, but it goes without saying that there may be a plurality of heating elements. The second heating element 31 having a low allowable temperature is, for example, a display element. In a liquid crystal projector that irradiates a display element with light from a light source and projects light from the display element with a projection lens, three display elements for R light, G light, and B light, for example, have low allowable temperatures. There are other polarizing plates. Here, assuming that there are a plurality of heating elements, the Nth heating element is denoted by reference numeral 33 and the other elements are not shown.

  The fan 221 has a low cooling capacity and cools the first heating element 21 with the wind sucked from the dustproof filter 100, and the fan 331 has a high cooling capacity and cools the second heating element 31 with the wind sucked from the dustproof filter 100. The fan 333 has a high cooling capacity and cools the Nth heating element. Although each fan is illustrated as cooling one heating element, the present invention is not limited to this, and a plurality of heating elements may be cooled by one fan.

  In the dustproof filter 100 according to the first embodiment, a dustproof filter that cools a heating element having a high allowable temperature and a dustproof filter provided in an air passage that cools a heating element having a low allowable temperature are common, and the housing of the apparatus Is formed on one of the upper surface, the lower surface, and the side surface.

  Further, the ventilation duct 200 according to the first embodiment is not divided on the dustproof filter 100 side, but the ventilation duct 200a that forms an air passage for cooling the heating element having a high allowable temperature from a predetermined place and the heating element having a low allowable temperature. It is formed by a dividing portion 201 that divides the air duct 200b that forms an air passage for cooling the air. The first heating element 21 and the fan 221 are provided on the ventilation duct 200a side, and the second heating element 31, the fan 331,..., The Nth heating element 33 and the fan 333 are provided on the ventilation duct 200b side. Yes.

  The control circuit 6 includes, for example, a CPU (Central Processing Unit) having a calculation control function, and controls the entire apparatus based on a program stored in a ROM (not shown) while appropriately using a work memory (not shown). The clogging detection process of the dustproof filter is performed.

  The cooling device for the liquid crystal projector is formed as described above. Therefore, when the dustproof filter 100 is not clogged, air is taken in from the dustproof filter 100 and flows through the ventilation ducts 200a and 200b in the ventilation duct 200 as indicated by arrows 801, 802, and 803. However, when the dust filter 100 becomes clogged, an air flow from the fan side having a low static pressure toward the fan side having a high static pressure is generated due to a difference in cooling capacity of the fans. In the first embodiment, since the fan 221 has a small cooling capacity, the static pressure and the air volume are small. On the other hand, since the fans 331 and 333 have a large cooling capacity, the static pressure and the air volume are large. Accordingly, an air flow is generated in the direction of the arrow 810. The first heating element 21 has a high heat generation temperature. When the dust filter 100 is clogged, an air flow is generated in the direction of the arrow 810, so that the warm air whose temperature has been raised by the first heating element 21 flows backward through the ventilation duct 200a to the ventilation duct 200b side.

  Therefore, in the first embodiment, the second temperature detection circuit 4 for temperature detection is provided only in the ventilation duct 200a. When a reverse flow occurs due to the clogging of the dustproof filter 100, the warm air whose temperature has been raised by the first heating element flows backward in the ventilation duct 200a, so that the temperature detected by the second temperature detection circuit 4 suddenly increases. To do.

  FIG. 2 is a diagram illustrating the relationship between the detected temperature and the clogging rate. T101 is the outside air temperature detected by the first temperature detection circuit 3, and T102 is the internal temperature of the ventilation duct 200a detected by the second temperature detection circuit 4. ΔT is a difference temperature between the internal temperature T102 and the outside air temperature T101 when not clogged. ΔT103 is a difference temperature represented by the equation (T102−T101−ΔT), and indicates a temperature change due to clogging. ΔT104 indicates a predetermined threshold value for determining clogging detection. In the first embodiment, the threshold level includes different levels α and β, which will be described later. In the following description, the difference temperature indicates ΔT103.

  As is apparent from FIG. 2, when the dust filter is clogged, the difference in temperature ΔT103 has a sufficiently large temperature change compared to the case where the temperature is detected by separating the ventilation ducts 200a and 200b into two ducts. . Along with this, ΔT104, which is a predetermined threshold for detecting clogging of the dustproof filter, can be increased. As a result, even if the temperature detection circuit has some variation in detection temperature (usually 2 to 3 ° C.), the influence on the clogging detection is relatively reduced, so that the clogging of the dustproof filter can be detected well. It becomes possible. In order to detect clogging early and increase the temperature difference, the second temperature detection circuit 4 is preferably provided at a position close to the fan 221 in the ventilation duct 200a.

  At this time, since only one temperature detection circuit 4 is used for measuring the internal temperature in the ventilation duct 200, the cost can be reduced as compared with the conventional case.

  Next, a control process of the control circuit 6 according to the first embodiment will be described with reference to FIG. The control circuit 6 periodically performs the clogging detection process of the dustproof filter at predetermined time intervals. When the clogging detection process is started, first, in step 1 (hereinafter, “S”), the outside temperature T101 and the inside temperature T102 are set using the first temperature detection circuit 3 and the second temperature detection circuit 4. To detect. Next, a difference temperature ΔT103 between the internal temperature T102 and the outside air temperature T101 is calculated (S2). Then, in S3, it is determined whether or not the difference temperature ΔT103 has exceeded a predetermined threshold value α at which a clogging detection warning is displayed. If NO in S3, the clogging detection process is terminated, and if YES, the process proceeds to S4.

  In S4, it is determined whether or not the difference temperature ΔT103 exceeds a predetermined threshold value β for displaying an error indicating clogging detection. If NO in S4 (that is, if the difference temperature ΔT103 is equal to or less than the threshold value β), the process proceeds to S5, and the control circuit 6 displays that it is time to replace the dust filter, and the second heating element 31 having a low allowable temperature is displayed. ,..., A warning display for notifying that the reliability of the Nth heating element 33 is lowered is performed on the display device 7. Then, the process ends.

  If YES in S4 (that is, if the difference temperature ΔT103 is equal to or greater than the threshold value β), the process proceeds to S6, and the control circuit 6 assumes that the dustproof filter has been clogged, and the life of the heating element (particularly the second having a low allowable temperature). From the viewpoint of the life of the heating elements 31,..., The life of the Nth heating element 33), the power source for supplying heat energy to the heating elements is turned off (however, the fan lowers the temperature of the heating elements at this time). Therefore, it goes without saying that it is operated for a predetermined time). For example, when the apparatus is a liquid crystal projector, the optical component generates heat upon receiving light from the light source, and thus stops the light emission of the light source. For example, if the device is a semiconductor device, the power source of the heating element is turned off. Then, in order to notify the user that the dustproof filter is clogged in S7, the clogging state is displayed on the display device 7, and the process is terminated.

  FIG. 4 shows an embodiment of the temperature detection circuit. FIG. 4 shows the first temperature detection circuit 3 as a representative of the temperature detection circuit. It goes without saying that other temperature detection circuits are formed in the same manner. In the first embodiment, the thermistor 303 is used as the temperature sensor. A current is passed through the thermistor 303 from the DC power supply 301 via the resistor R1, and the voltage (analog voltage) across the thermistor 303 is converted into digital data by the AD converter 304. Then, the CPU 601 serving as the control circuit 6 reads the digital data from the AD converter 304, detects the temperature, and combines with the temperature detection values of the other temperature detection circuits, based on these temperature detection values, as shown in FIG. Perform clogging detection processing.

  FIG. 5 is an example of a display device. In FIG. 5, the display device 7 according to the first embodiment includes an LED 1 that displays a warning and an LED 2 that displays a clogging state. When the control circuit 6 detects that the difference temperature ΔT103 is not less than a predetermined threshold value α and not more than β, it outputs a voltage of 1.4 V or more to the base (point A) of the transistor TR1. As a result, the transistor TR1 is turned on, a current flows from the DC power source 701 to the LED 1 via the resistor R2, the LED 1 emits light, and a warning is displayed. Further, when the control circuit 6 detects that the difference temperature ΔT103 is equal to or higher than the predetermined threshold value β, it outputs a voltage of 1.4 V or higher to the base (point B) of the transistor TR2. Thereby, the transistor TR2 is turned on, a current flows from the DC power source 701 to the LED 2 via the resistor R3, the LED 2 emits light, and a clogging state display is made.

  With reference to FIG. 6, the clogging detection device for a dustproof filter of Example 2 will be described. In FIG. 6, 5 is an air volume detection sensor for detecting the air volume passing through the duct 200a. In FIG. 6, the description of the same symbols and functions as those in the first embodiment is omitted.

  In the second embodiment, as in the first embodiment, when the dustproof filter 100 becomes clogged, the air flow (arrow) from the fan side having a small static pressure toward the fan side having a large static pressure is caused by the difference in cooling capacity of the fan. 810) occurs. Therefore, the airflow detection sensor 5 detects in advance the difference in airflow between normal use and clogging, and sets a threshold value for determining clogging detection, thereby clogging the dustproof filter 100. To detect.

  According to the second embodiment, the same effect as the first embodiment can be obtained. In the second embodiment, the air volume detection sensor 5 is arranged in the duct 200a. However, it goes without saying that the same effect can be obtained by arranging the air volume sensor 5 in the duct 200b and detecting the air volume passing through the duct 200b. Further, when the dustproof filter 100 is clogged, the predetermined amount of wind toward the fan 221 is directed to the fan 331, that is, even if the air volume detection sensor 5 is disposed in the vicinity of the dividing unit 201. Needless to say, the effect of.

FIG. 3 is a schematic diagram illustrating a clogging detection device for a dustproof filter according to a first embodiment. FIG. 3 is a diagram for explaining a relationship between a detected temperature and a clogging rate in the first embodiment. 6 is a flowchart of clogging detection processing according to the first embodiment. An example of a temperature detection circuit. An example of a display device. FIG. 6 is a schematic diagram illustrating a clogging detection device for a dustproof filter according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... 1st temperature detection circuit, 4 ... 2nd temperature detection circuit, 5 ... Air volume detection sensor, 6 ... Control circuit, 7 ... Display device, 21 ... 1st heating element, 31 ... 2nd heating element, 33 ... Nth heating element, 100 ... dust filter, 200 ... ventilation duct, 201 ... dividing part, 221 ... fan, 301 ... DC power supply, 303 ... thermistor, 304 ... AD converter, 331,333 ... fan, 601 ... CPU 701 DC power source 801 802 803 810 arrow.

Claims (10)

A detection device that detects clogging of a dustproof filter provided on any one of an upper surface, a lower surface, and a side surface of a housing,
At least first and second heating elements;
A first fan that sucks wind from the dust filter and cools the first heating element;
A second fan having a rotational speed different from that of the first fan, by sucking air from the dust filter to cool the second heating element;
A duct having a dividing portion that divides the wind from the dustproof filter from a predetermined location into a portion leading to the first fan and a portion leading to the second fan;
Detecting a temperature outside the device, and a first temperature detector disposed outside the device;
Detecting a temperature in the device; and a second temperature detecting unit disposed in the device;
A difference temperature between the temperature detected by the first temperature detection unit and the temperature detected by the second temperature detection unit is detected, and whether or not the difference temperature is within a predetermined threshold range. And a control unit for determining. The detection device according to claim 1,
The detection device, wherein the second temperature detection unit is arranged in the vicinity of the fan having a small number of rotations among the first and second fans. The detection device according to claim 1 or 2,
The detection device includes:
A detection apparatus comprising: a display device that displays the determination when the control unit determines that the difference temperature is within a predetermined threshold range. The detection device according to claim 1, wherein
The detection device includes:
At least a power supply for supplying current to the first fan;
When the control unit determines that the difference temperature is within a predetermined threshold range, the power supply unit varies the amount of supplying the current. A detection device that detects clogging of a dustproof filter provided on any one of an upper surface, a lower surface, and a side surface of a housing,
At least first and second heating elements;
A first fan that sucks wind from the dust filter and cools the first heating element;
A second fan having a rotational speed different from that of the first fan, by sucking air from the dust filter to cool the second heating element;
A duct having a dividing portion that divides the wind from the dustproof filter from a predetermined location into a portion leading to the first fan and a portion leading to the second fan;
An air volume detection sensor disposed in the apparatus;
And a control unit that determines whether or not the differential airflow detected by the airflow detection sensor is within a predetermined threshold range. The detection device according to claim 5,
The air volume detection sensor is arranged in the vicinity of the first or second fan. The detection device according to claim 5,
The said air volume detection sensor is arrange | positioned in the vicinity of the said division part, The detection apparatus characterized by the above-mentioned. The detection device according to claim 5, wherein
The detection device includes:
A detection apparatus comprising: a display device for displaying the determination when the control unit determines that the differential airflow volume is within a predetermined threshold range. The detection device according to claim 5, wherein
The detection device includes:
At least a power supply for supplying current to the first fan;
When the control unit determines that the differential airflow volume is within a predetermined threshold range, the power supply unit varies the amount of supplying the current. A display device that irradiates a display element with light from a light source, and projects light from the display element with a projection lens,
A display device comprising at least the detection device according to claim 1.

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