JP5034631B2 - Overheat protection device and projector with overheat protection device - Google Patents

Description

  The present invention relates to an electric device having a heat source, and more particularly, to an apparatus that blows cooling air with a cooling fan and cools the heat source, an overheat protection device that prevents an abnormal temperature rise in the device, and a projector including the overheat protection device It is about.

  Conventionally, there is a projection display device such as a projector as an electric apparatus having a large heat source. For example, a liquid crystal projector modulates light emitted from a light source such as an ultra-high pressure mercury lamp with a liquid crystal display element having a transmissive or reflective light modulation function, and projects the light onto a screen via a projection lens to display an image. It is what you do.

  In other words, the liquid crystal projector is driven by red, green, and blue color signals by means of splitting the light emitted from the light source into the three primary colors of red, green, and blue, and with red light, green light, and blue light. The liquid crystal panel includes three liquid crystal panels and a projection lens that synthesizes the light transmitted through the liquid crystal panels and projects the enlarged light on the screen.

  In such a liquid crystal projector, a mercury lamp or the like is used as a light source, and heat is generated from the light source, and the liquid crystal panel is irradiated with light from the light source, thereby being arranged on the liquid crystal panel and its incident side and emission side. Since the polarizing plate to be heated is heated as it is, it becomes a high temperature and adversely affects the image display.

  In order to prevent this, outside air is usually introduced by a cooling fan, and cooling air is guided to the light source, the liquid crystal panel, and the polarizing plate.

  In general, in the vicinity of this cooling fan, in order to guide outside air to the cooling fan, the intake port provided in the cabinet of the liquid crystal projector main body and the intake port of the cooling fan are connected by an intake duct. In order to prevent dust and dirt entering from the mouth from adhering to the liquid crystal panel and the polarizing plate, an air filter is attached in the vicinity of the air inlet.

  However, if dust or debris accumulates in this air filter and becomes clogged or blocked by paper or the like, the outside air is not introduced, so that the cooling effect is reduced, and therefore it is an object to be cooled. There has been a drawback that the temperature of the polarizing plate and the liquid crystal panel rises, leading to deterioration.

  Patent Document 1 and Patent Document 2 are examples of measures taken when the air filter provided at the intake port is blocked by dust or dust as described above.

  In the example of Patent Document 1, when the air filter is clogged, the rotation speed of the cooling fan provided near the air filter attached to the air inlet formed in the projector casing is detected to fluctuate. Then, a protective operation such as shutting off the power of the projector is performed.

In the example of Patent Document 2, the voltage between the terminals of the thermistor arranged in the vicinity of the air filter is detected to fluctuate when the air filter is clogged, and the rotation speed of the cooling fan is controlled. It performs protection operations such as shutting off the power supply.
JP 2002-152634 A JP-A-6-221599

  However, when the device is used at a high altitude with a low atmospheric pressure, the air density decreases, and therefore the rotation speed fluctuates even though the air filter is not clogged. Will be detected.

  For the same reason, even in the case of Patent Document 2, although the air filter is not clogged, the voltage between terminals of the thermistor fluctuates and is erroneously detected.

  That is, although the air filter is not clogged, the malfunction of the device is caused such that the rotation speed of the cooling fan is controlled or the power is shut off.

  For this reason, in order for an apparatus to detect the clogging of an air filter normally, it was necessary to set restrictions on the conditions of the external pressure used.

  The present invention solves the above-mentioned problem, by measuring the outside air temperature and the outside air pressure at which the device is used, thereby grasping the use environment and accurately determining the degree of clogging of the air filter. , Equipped with an overheat protection device and overheat protection device that can control the number of rotations of the cooling fan, shut off the power supply, and give a sign to prompt the user to clean or replace the air filter according to the usage environment The purpose is to provide a projector.

  In order to solve the above-described problem, the invention according to claim 1 of the present invention includes a first intake port and a second intake port for introducing outside air into the device, the first intake port and the first intake port. A first cooling fan and a second cooling fan respectively disposed in the vicinity of the second air inlet, and a first cooling fan rotation speed for controlling the rotation of the first cooling fan and the second cooling fan, respectively. A control unit and a second cooling fan rotation speed control unit; a first cooling fan rotation number detection unit and a second cooling fan rotation that respectively detect rotation speeds of the first cooling fan and the second cooling fan; A number detection unit, an air filter provided between the first air inlet and the first cooling fan to remove dust from outside air, an outside air temperature detection unit for detecting outside air temperature, the outside air temperature and Rotation of the second cooling fan And an air pressure clogging degree calculating unit for calculating the clogging degree of the air filter from the rotation number of the first cooling fan and the value of the external air pressure. The overheat protection device has the effect of accurately calculating the degree of clogging of the filter regardless of the ambient temperature or atmospheric pressure, which is the usage environment of the device.

According to a second aspect of the present invention, there is provided a first thermistor disposed in the vicinity of the first cooling fan, a current source for supplying a current to the first thermistor, and a first temperature sensor for detecting a temperature of the first thermistor. The air filter clogging degree calculating unit calculates a degree of clogging of the air filter from the external pressure and the first thermistor temperature. The overheat protection device described in 1) has the effect of accurately calculating the degree of clogging of the filter regardless of the outside air temperature or the outside air pressure that is the usage environment of the device.

According to a third aspect of the present invention, there is provided a second thermistor disposed in the vicinity of the second cooling fan, a second current source for supplying a current to the second thermistor, and the temperature of the second thermistor. 2. The overheat protection according to claim 1 , further comprising: a second thermistor temperature detection unit that detects, wherein the external air pressure calculation unit calculates an external air pressure from the external air temperature and the second thermistor temperature. The device has an effect of accurately calculating the degree of clogging of the filter regardless of the outside air temperature or the atmospheric pressure as the use environment of the device.

  According to a fourth aspect of the present invention, the first cooling fan rotation speed control unit and the second cooling fan rotation speed control unit are respectively responsive to an external air pressure value from the external air pressure calculation unit, 2. The overheat protection device according to claim 1, wherein the number of revolutions of the first cooling fan and the second cooling fan is controlled, and responds to a change in cooling efficiency due to an external pressure. Thus, the rotation speed of the cooling fan is changed to ensure the quality and reliability of the components in the equipment.

  According to a fifth aspect of the present invention, the first cooling fan rotation speed control unit and the second cooling fan rotation speed control unit set the air filter clogging degree value from the air filter clogging degree calculation unit. In response, the number of rotations of the first cooling fan and the second cooling fan is controlled. The overheat protection device according to claim 1, wherein the overheat protection device according to claim 1 is used. In response to the change in cooling efficiency, the rotation speed of the cooling fan is changed to ensure the quality and reliability of components in the equipment.

  The invention according to claim 6 is the overheat protection device according to claim 1, further comprising warning means for warning when the value of the external air pressure from the external air pressure calculation unit falls below a predetermined value. It has the effect of ensuring the quality and reliability of the components in the device by urging the user a warning in response to the change in cooling efficiency due to the external atmospheric pressure.

  The invention according to claim 7 is provided with warning means for warning when the value of the air filter clogging degree from the air filter clogging degree calculating unit exceeds a predetermined value. This is an overheat protection device that ensures the quality and reliability of the components in the equipment by prompting the user in response to the change in cooling efficiency due to the degree of clogging of the air filter. Have

  The invention according to claim 8 is provided with a shut-off means for shutting off a heat source or a power source in the device when the value of the external air pressure from the external air pressure calculation unit falls below a predetermined value. It is an overheat protection device and has the effect of ensuring the quality and reliability of the components in the equipment by shutting off the heat source or power supply in the equipment in response to the change in cooling efficiency due to the external air pressure. .

  The invention according to claim 9 includes a shut-off means for shutting off a heat source or a power source in the device when the air filter clogging degree value from the air filter clogging degree calculating unit exceeds a predetermined value. The overheat protection device according to claim 1, wherein the quality of parts in the device is cut off by shutting off a heat source or a power source in the device in response to a change in cooling efficiency depending on the degree of clogging of the air filter. And has the effect of ensuring reliability.

  Invention of Claim 10 is a projector provided with the light source, the display element, the spectroscopic means, the light synthesis means, the projection means, and the overheat protection device according to any one of Claims 1 to 9, and the light source This protects the display element and the like from the heat generated from the heat and ensures the quality and reliability.

  The invention described in claim 11 is a projector having an overheat protection device according to claim 10, wherein the light source is a lamp, the display element is a liquid crystal panel, the spectroscopic means is a dichroic mirror, and the light combining means is a dichroic prism. In addition, the liquid crystal panel and the like are protected from heat generated from the lamp, and the quality and reliability are ensured.

  The invention described in claim 12 is provided with a duct for guiding outside air introduced from the first air inlet to the display element and the spectroscopic means via the first cooling fan. 10. A projector comprising the overheat protection device according to claim 10, wherein the outside air from which dust and dirt have been removed is blocked from the outside air introduced from the second air inlet, and efficiently led to the display element and the spectroscopic means. It has the action.

  As described above, the overheat protection device and the projector equipped with the overheat protection device of the present invention have an advantage that the degree of clogging of the air filter can be accurately calculated because the outside air temperature and the outside air pressure can be known.

  In addition, since the rotation speed of the cooling fan can be changed according to changes in the external air pressure and the degree of clogging of the air filter, the quality and reliability of the components in the equipment can be ensured, and the cooling fan Since the rotation speed is not increased, there is an advantage that the silent performance of the device can be secured at the same time.

  In addition, the user can be alerted according to changes in the external air pressure and the degree of clogging of the air filter, so there is an advantage that the quality and reliability of the parts in the equipment can be secured by improving the usage environment. is there.

  In addition, since the heat source or power supply in the device can be shut off according to the change in the external air pressure or the degree of clogging of the air filter, there is an advantage that the components in the device can be forcibly protected.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration when the overheat protection device of Embodiment 1 of the present invention is applied to a liquid crystal projector.

  In FIG. 1, reference numeral 1 denotes a housing of a liquid crystal projector. The housing 1 is provided with a first air inlet 2 and a second air inlet 3, and an air filter 4 is provided in the first air inlet 2. Is attached. A first cooling fan 5 and a second cooling fan 6 are attached in the vicinity of the first air inlet 2 and the second air inlet 3, respectively. One outside air 7 is taken into the first cooling fan 5, and the second outside air 8 taken from the second air inlet 3 is taken into the second cooling fan 6.

  Further, an air filter 4 is located between the first air inlet 2 and the first cooling fan 5, and the first outside air 7 passes through the air filter 4 and is contained in the first outside air 7. In addition, the first cooling fan 5 is configured so as to remove dust and dust.

  Further, the first cooling fan 5 is driven and rotated by the first cooling fan rotation speed control unit 10, thereby taking in the first outside air 7 taken in from the first intake port 2, and the second cooling fan 5. The cooling fan 6 is driven and rotated by the second cooling fan rotation speed control unit 11, thereby taking in the second outside air 8 taken in from the second air inlet 3, and cooling air into the housing 1. I am blowing.

  In addition, a power supply circuit 12, a lamp driving circuit 13, a video processing circuit 14, a liquid crystal panel driving circuit 15, and a CPU 16 as a control circuit are provided in the housing 1.

  The power supply circuit 12 converts an alternating voltage from an alternating current power source into a direct current voltage and supplies the direct current voltage to each circuit described above.

  The lamp driving circuit 13 drives and drives a lamp 17 as a light source, and irradiates the liquid crystal panel 18 with light from the lamp 17. The liquid crystal panel 18 modulates and emits the light from the lamp 17 according to the video signal, and projects it onto the screen via the projection lens 19 to display an image.

  The video processing circuit 14 processes the video signal supplied to the input terminal 20 and supplies the RGB signal to the liquid crystal panel drive circuit 15.

  Further, a first fan rotation speed detector 21 is connected to the first cooling fan 5, and the first rotation speed detector 21 detects the rotation speed of the first cooling fan 5 and detects the air filter. The rotation speed information is provided to the clogging degree calculation unit 23. Similarly, a second fan speed detector 22 is connected to the second cooling fan 6, and the second speed detector 22 detects the speed of the second cooling fan 6 and removes it. The rotational speed information is provided to the atmospheric pressure calculation unit 24.

  The CPU 16 controls the first cooling fan rotation speed control unit 10, the second cooling fan rotation speed control unit 11, the power supply circuit 12, the lamp drive circuit 13, and the video processing circuit 14, and is powered by a user operation. In addition to turning on / off, the circuits 12, 13, and 14 are controlled in response to information from the clogging degree calculation unit 23 and the external air pressure calculation unit 24. Further, the CPU 16 supplies information such as message characters to the video processing circuit 14 so that it can be combined with the video signal.

  Next, an arrangement structure of the optical unit and the cooling fan of the liquid crystal projector described above will be described with reference to FIGS.

  In FIG. 2, an optical block 25 is provided in the housing 1 as an optical unit, in which a lamp 17, liquid crystal panels 18R, 18G, and 18B, dichroic mirrors DM1 and DM2 serving as spectroscopic means, and light synthesizing means are provided. A dichroic prism 26 is arranged. An air intake duct 9 is provided so as to connect the first air inlet 2 and the first cooling fan 5, and cooling from the first cooling fan 5 to the liquid crystal panels 18 R, 18 G, and 18 B and the dichroic prism 26 is performed. A liquid crystal panel cooling duct 27 for guiding the wind is provided.

  By these ducts, the first outside air 7 is blocked from the second outside air 8, and the outside air 7 from which dust and dirt are removed can be efficiently guided to the panels 18R, 18G, 18B and the dichroic prism 26.

  Light from the lamp 17 enters the dichroic mirror DM1. The dichroic mirror DM1 reflects blue light and transmits red and green light. The red and green light transmitted through the dichroic mirror DM1 is incident on the dichroic mirror DM2, and the dichroic mirror DM2 reflects green light and transmits red light.

  Of the red, green and blue light thus dispersed, the blue light is reflected by the mirror M1 and enters the liquid crystal panel 18B, the green light is directly incident on the liquid crystal panel 18G, and the red light is reflected by the mirrors M2 and M3. The light enters the panel 18R.

  The liquid crystal panels 18R, 18G, and 18B are provided with polarizing plates (not shown) on the incident side and the emission side, and light transmitted through the liquid crystal panels 18R, 18G, and 18B is transmitted to the dichroic prism 26 as red, green, and blue light. Are combined so that an image can be projected onto the screen via the projection lens 19.

  FIG. 3 is a view showing a cooling structure of the liquid crystal panel in the optical block 25 of FIG.

  As shown in FIG. 3, the cooling air from the first cooling fan 5 is guided to the liquid crystal panels 18R, 18G, and 18B by the liquid crystal panel cooling duct 27 provided in the casing 1.

  As shown in FIGS. 2 and 3, by driving the first cooling fan 5, the first outside air 7 from the first air inlet 2 is contained through the air filter 4 to contain dust and dirt. Is removed and sucked in by the first cooling fan 5 while passing through the intake duct 9, and further, the cooling air is sent to the liquid crystal panels 18R, 18G, 18B through the liquid crystal panel cooling duct 27, and the liquid crystal panels 18R, 18G , 18B and the like are cooled, and dust and dirt are prevented from adhering to the liquid crystal panels 18R, 18G, 18B.

  By the way, when the air filter 4 is attached to the first air inlet 2 and the air filter 4 is clogged with dust or dust, or when the first air inlet 2 is blocked with paper or the like. The first outside air 7 does not flow to the first cooling fan 5, and the liquid crystal panels 18R, 18G, and 18B are heated and deteriorated by the heat generated by the lamp 17.

  On the other hand, when the device is used at a high altitude, the density of the air decreases as the atmospheric pressure decreases. For this reason, since the density of the 1st external air 7 and the 2nd external air 8 also falls, cooling efficiency will reduce and the temperature rise of the whole apparatus will be caused.

  In order to suppress the deterioration of the liquid crystal panels 18R, 18G, 18B when the air filter 4 is clogged, the rotational speed of the first cooling fan 5 is increased or the user is clogged with the air filter 4. It is effective to warn of the occurrence or to cut off the heat source or power supply in the device when the degree of clogging is significant.

  In addition, when the device is used at high altitude, in order to ensure the reliability of the components in the device and the safety of the user, the components in the device including the first cooling fan 5 and the second cooling fan 6 are used. When the number of rotations of all the cooling fans is increased, or when the cooling fan is used at a very high place, a method of cutting off a heat source or a power source in the device is effective.

  As described above, when the air filter 4 is clogged or when the device is used at a high altitude, the temperature of the components in the device rises.

  In the present invention, the degree of clogging in the air filter 4 is detected by the clogging degree calculation unit 23 as described above, and the external atmospheric pressure calculation unit 24 determines how much the external atmospheric pressure is used by the device. And overheating of the device is to be protected by the control of the CPU 16.

  Next, the operation of the overheat protection device of the present invention will be described.

  In FIG. 1, when the device is used at a high altitude, the external air pressure decreases, so the air density decreases. For this reason, since the load added to the wing | blade of a cooling fan changes, the rotation speed of the cooling fan in an apparatus changes. The viscosity of the lubricating oil used in the motor unit of the cooling fan also changes depending on the environmental temperature in which the device is used, and the rotational speed of the cooling fan changes.

  Utilizing this characteristic, in order to measure the use environment temperature of the device, for example, the use temperature measured by the outside air temperature detection unit 28 configured by the thermistor or the like provided near the second air inlet 3, The second cooling under the temperature and atmospheric pressure conditions in which the device is used, which has been converted into data based on the rotation speed value of the second cooling fan 6 measured by the second cooling fan rotation speed detector 22. From the relationship of the rotational speed of the fan 6, the external air pressure used by the device can be detected by the external air pressure calculation unit 24.

  Further, when the air filter 4 is clogged, the amount of the first outside air 7 that can be sucked by the first cooling fan 5 is decreased, and therefore the rotational speed of the first cooling fan 5 is changed. In order to measure the degree of clogging of the air filter 4 using this feature, the operating temperature measured by the outside air temperature detecting unit 28, the outside air pressure calculated by the outside air pressure calculating unit 24, and the first cooling Based on the value of the rotation speed of the first cooling fan 5 measured by the fan rotation speed detection unit 21, the data is preliminarily converted under the conditions of the temperature and pressure used by the device and the degree of clogging of the air filter 4. The actual clogging degree of the air filter 4 can be detected by the clogging degree calculation unit 23 from the relationship of the rotation speed of the first cooling fan 5.

  In the present invention, the clogging degree of the air filter 4 calculated by the clogging degree calculation unit 23 is supplied to the CPU 16, so that the first cooling fan rotation speed control is performed according to the clogging degree of the air filter 4. Usually, the number of rotations of the first cooling fan 5 is increased by the unit 10, or a warning message signal such as “Please clean the air filter” is generated in the video processing circuit 14, and supplied from the input terminal 20. Is superimposed on the video signal to prompt the user to clean or replace the air filter 4, or the lamp drive circuit 13 is controlled to reduce the light amount of the lamp 17, or the power supply circuit 12 is controlled to shut off the power source and overheat. I try to protect it.

  Furthermore, the value of the external air pressure calculated by the external air pressure calculation unit 24 is supplied to the CPU 16, so that the first cooling fan rotation speed control unit 10 and the second cooling fan rotation speed control unit 11 according to the external air pressure. In addition, when there are other cooling fans, the rotational speed control unit thereof increases the rotational speed of the cooling fan in the device, or controls the lamp driving circuit 13 to decrease the light amount of the lamp 17. The power supply circuit 12 is controlled to cut off the power supply and perform overheat protection.

(Embodiment 2)
FIG. 4 is a block diagram showing a configuration when the overheat protection device according to the second embodiment of the present invention is applied to a liquid crystal projector.

  4, the same components as those in FIG. 1 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  4 is different from FIG. 1 in that a first air volume detection unit 29 is connected in the vicinity of the first cooling fan 5. In this method, for example, a current is passed through a thermistor to generate heat, and the temperature of the thermistor changes according to the amount of air flowing therethrough, and the amount of air is detected by a change in resistance.

  The first air volume detection unit 29 detects the amount of the first outside air 7 flowing through the first cooling fan 5 and provides the flow rate information of the first outside air 7 to the air filter clogging degree calculation unit 23. .

  At this time, if the device is used at a high altitude, the external air pressure decreases, so the air density decreases. For this reason, since the quantity of the 1st external air 7 which flows into the 1st cooling fan 5 reduces, the flow volume which the 1st air volume detection part 29 detects apparently becomes low.

  In addition, when the air filter 4 is clogged, the amount of the first outside air 7 that can be sucked by the first cooling fan 5 is reduced, so that the flow rate detected by the first air volume detection unit 29 is apparently reduced. .

  In order to measure the degree of clogging of the air filter 4 using this feature, the operating temperature measured by the outside air temperature detecting unit 28, the outside air pressure calculated by the outside air pressure calculating unit 24, and the first air volume Conditions for the temperature and pressure at which the device is used and the degree of clogging of the air filter 4 preliminarily converted into data based on the flow rate of the first outside air 7 flowing through the first cooling fan 5 measured by the detection unit 29 The clogging degree of the air filter 4 can be detected by the clogging degree calculation unit 23 from the relationship of the flow rate of the first outside air 7 flowing to the first cooling fan 5 below.

(Embodiment 3)
FIG. 5 is a block diagram showing a configuration when the overheat protection device according to the second embodiment of the present invention is applied to a liquid crystal projector.

  In FIG. 5, the same components as those in FIG. 1 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  5 is different from FIG. 1 in that a second air volume detection unit 30 is connected in the vicinity of the second cooling fan 6. In this method, for example, a current is passed through a thermistor to generate heat, and the temperature of the thermistor changes according to the amount of air flowing therethrough, and the amount of air is detected by a change in resistance.

  The second air volume detection unit 30 detects the amount of the second outside air 8 flowing through the second cooling fan 6 and provides the flow rate information of the second outside air 8 to the outside air pressure calculation unit 24.

  At this time, if the device is used at a high altitude, the external air pressure decreases, so the air density decreases. For this reason, since the quantity of the 2nd external air 8 which flows into the 2nd cooling fan 6 reduces, the flow volume which the 2nd air volume detection part 30 detects apparently becomes low.

  In order to measure the use environment temperature of the equipment using this feature, for example, the use temperature measured by the outside air temperature detection unit 28 configured by a thermistor or the like provided in the vicinity of the second air inlet 3 and the like. Based on the value of the flow rate of the second outside air 8 flowing through the second cooling fan 6 measured by the second air volume detection unit 30, the data is preliminarily converted into the first data under the temperature and pressure conditions used by the device. From the relationship between the flow rate values of the second outside air 8, the outside air pressure used by the device can be detected by the outside air pressure calculation unit 24.

  As described above, according to the present invention, appropriate overheat protection can be performed without generating useless noise in accordance with the clogging of the air filter 4 or the altitude used, which causes a temperature rise in the device. .

  In the above invention, the three-plate type liquid crystal projector device has been described, but it is needless to say that the overheat protection device of the present invention can also be applied to electric equipment having other heat sources.

  The overheat protection device and the projector equipped with the overheat protection device according to the present invention measure the outside air temperature, the outside air pressure, and the degree of clogging of the air filter in which the electric device having the heat source is used, and thereby noise depending on the situation. It is useful as an overheat protection device for an electric device having a fan that blows cooling air and a projector.

Block diagram when the overheat protection device of Embodiment 1 of the present invention is applied to a liquid crystal projector The top view which shows the optical block of the overheat protection apparatus of Embodiment 1 of this invention The figure which shows the cooling structure of the liquid crystal panel in the optical block of the overheat protection apparatus of Embodiment 1 of this invention Block diagram when the overheat protection device of Embodiment 2 of the present invention is applied to a liquid crystal projector Block diagram when the overheat protection device of Embodiment 3 of the present invention is applied to a liquid crystal projector

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing | casing 2 1st inlet port 3 2nd inlet port 4 Air filter 5 1st cooling fan 6 2nd cooling fan 7 1st outside air 8 2nd outside air 9 Intake duct 10 1st cooling fan rotation Number control unit 11 Second cooling fan rotation number control unit 12 Power supply circuit 13 Lamp drive circuit 14 Video processing circuit 15 Liquid crystal panel drive circuit 16 CPU
DESCRIPTION OF SYMBOLS 17 Lamp 18 Liquid crystal panel 19 Projection lens 20 Input terminal 21 1st fan rotation speed detection part 22 2nd fan rotation speed detection part 23 Clogging degree calculation part 24 External pressure calculation part 25 Optical block 26 Dichroic prism 27 Liquid crystal panel cooling Duct 28 Outside air temperature detector 29 First air volume detector 30 Second air volume detector

Claims (12)

A first inlet and a second inlet for introducing outside air into the device;
A first cooling fan and a second cooling fan respectively disposed in the vicinity of the first air inlet and the second air inlet;
A first cooling fan rotation speed control unit and a second cooling fan rotation speed control unit that respectively control rotations of the first cooling fan and the second cooling fan;
A first cooling fan rotation speed detection unit and a second cooling fan rotation speed detection unit that respectively detect rotation speeds of the first cooling fan and the second cooling fan;
An air filter provided between the first air inlet and the first cooling fan to remove dust from the outside air;
An outside air temperature detector for detecting outside air temperature,
An external air pressure calculation unit for calculating an external air pressure from the external air temperature and the rotation speed of the second cooling fan;
An air filter clogging degree calculating unit that calculates the degree of clogging of the air filter from the rotation speed of the first cooling fan and the value of the external pressure;
With overheat protection device. A first thermistor disposed in the vicinity of the first cooling fan; a current source for supplying a current to the first thermistor; and a first thermistor temperature detecting unit for detecting a temperature of the first thermistor. ,
2. The overheat protection device according to claim 1, wherein the air filter clogging degree calculation unit calculates a clogging degree of the air filter from the external air pressure and the first thermistor temperature. A second thermistor disposed in the vicinity of the second cooling fan; a second current source for supplying a current to the second thermistor; and a second thermistor temperature detecting unit for detecting the temperature of the second thermistor. And
The overheat protection device according to claim 1 , wherein the external air pressure calculation unit calculates an external air pressure from the external air temperature and the second thermistor temperature. The first cooling fan rotation speed control unit and the second cooling fan rotation speed control unit respond to the value of the external air pressure from the external air pressure calculation unit, and the first cooling fan and the second cooling fan The overheat protection device according to claim 1, wherein the number of rotations of the cooling fan is controlled. The first cooling fan rotation speed control unit and the second cooling fan rotation speed control unit respond to the value of the air filter clogging degree from the air filter clogging degree calculation unit, and The overheat protection device according to claim 1, wherein the number of rotations of the fan and the second cooling fan is controlled. The overheat protection device according to claim 1, further comprising a warning unit that warns when an external air pressure value from the external air pressure calculation unit falls below a predetermined value. The overheat protection device according to claim 1, further comprising warning means for warning when the air filter clogging degree value from the air filter clogging degree calculating unit exceeds a predetermined value. The overheat protection device according to claim 1, further comprising: a shut-off unit that shuts off a heat source or a power source in the device when an external air pressure value from the external air pressure calculation unit falls below a predetermined value. 2. The overheat protection device according to claim 1, further comprising: a shut-off unit that shuts off a heat source or a power source in the device when the value of the air filter clogging degree from the air filter clogging degree calculation unit exceeds a predetermined value. . The projector provided with the light source, the display element, the spectroscopic means, the light synthesis means, the projection means, and the overheat protection device according to any one of claims 1 to 9. The projector with an overheat protection device according to claim 10, wherein the light source is a lamp, the display element is a liquid crystal panel, the spectroscopic means is a dichroic mirror, and the light combining means is a dichroic prism. 11. The overheat protection device according to claim 10, further comprising a duct for guiding outside air introduced from the first air inlet to the display element and the spectroscopic unit via the first cooling fan. Projector.

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