JP2013015372A - Sensor fitting structure and projection type image displaying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor fitting structure that can accurately measure the flow rate of air flowing through a through hole without having to alter the configuration of an air flow rate sensor and the size of the through hole even when the air pressure difference in a space between one end and the other of the through whole penetrating a sensor fitting wall has become greater, and a projection type image displaying apparatus.SOLUTION: A duct 32, which is a sensor fitting wall in which a through hole 32A is formed, partitions a first space S1 and a second space S2 from each other. An air flow rate sensor 40, disposed in the first space S1 has an inlet 41 through which air flows in from the first space S1 and an outlet 42 through which the air from the inlet 41 flows out, detects the flow rate of the air having flowed in through the inlet 41. The air flow rate sensor 40 is so disposed that a gap C is left between the outlet 42 and the through hole 32A, and the outlet 42 is so disposed with spacing from the through hole 32A that, when an air pressure difference has arisen between spaces S1 and S2, air correspondingly flows into the through hole 32A from both the outlet 42 and the gap C.

Description

  The present invention relates to a sensor mounting structure in which an air volume sensor for detecting a flow rate of air flowing through a through hole is mounted on a sensor mounting wall in which the through hole is formed, and a projection display apparatus including the same. .

In a liquid crystal projector which is a projection type image display device, it is known to use an air volume sensor to detect clogging of an air filter (see, for example, Patent Document 1).
The air volume sensor described in Patent Document 1 has an inflow port into which detection target wind flows in and an outflow port that opens on the opposite surface, and the size of the outflow port of the air flow sensor is adjusted inside the mounting wall of the cooling fan. It is attached so as to correspond to the adjusted hole.

JP 2008-298957 A

  By the way, although the air volume sensor can accurately detect the flow rate of air flowing into the inlet at a flow velocity within a predetermined flow velocity range, the flow rate of air flowing into the inlet at a large flow velocity exceeding the flow velocity range is accurate. It cannot be detected. Therefore, if the air pressure difference in the space sandwiching the through hole increases, the flow velocity of the air flowing into the inlet of the air volume sensor increases because the air flows into the through hole. There is a risk that the flow rate cannot be detected accurately.

  In the sensor mounting structure described in Patent Document 1, when the air pressure difference in the space sandwiching the adjustment hole, which is a through hole of the sensor mounting wall, becomes large, the flow rate of air flowing through the adjustment hole cannot be detected with high accuracy. There is a fear. If the size (diameter) of the adjustment hole is reduced, the flow velocity of the air flowing into the inlet of the air flow sensor can be reduced, but there is a disadvantage that the pin of the mold for forming the adjustment hole is broken. In addition, the configuration of the air flow sensor can be changed to widen the flow velocity range in which the flow rate can be detected with high accuracy, but there are disadvantages such as an increase in the size of the air flow sensor and an increase in cost.

  The present invention has been made to solve the above-described problems, and the purpose of the present invention is to construct and penetrate the air flow sensor even when the air pressure difference in the space sandwiching the through hole of the sensor mounting wall becomes large. An object of the present invention is to provide a sensor mounting structure and a projection display apparatus that can accurately detect the flow rate of air flowing through a through-hole without changing the size of the hole.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is a sensor mounting structure in which an air volume sensor for detecting a flow rate of air flowing through the through hole is mounted on a sensor mounting wall in which the through hole is formed, The sensor mounting wall partitions the first space and the second space sandwiching the through hole, the sensor is provided in the first space, and the air volume sensor includes an inlet port through which air flows from the first space. And an outlet through which the air flowing into the same air volume sensor flows out from the inlet, and the flow rate of the air flowing into the inlet is detected so that a gap is formed between the outlet and the through hole. The air volume sensor is provided at the same time, and the first space and the through hole communicate with each other through the gap, so that an air pressure difference is generated between the first space and the second space. According It said outlet and so that air in the through hole from both the gap flows, the outflow port, characterized in that it is provided at a distance from the through hole. The air volume sensor is a sensor that detects the flow rate of air, and includes a wind speed sensor that detects the flow rate of air per predetermined time.

  According to the above-described invention, when an air pressure difference is generated between the first space and the second space, the gap formed between the outlet of the air flow sensor and the through hole is passed according to the pressure difference. Then, air flows into the through hole from the first space, and air flows into the through hole from the first space through the inlet and outlet of the air volume sensor. At this time, as the flow velocity of the air flowing through the through-hole increases, the flow velocity of the air passing through the gap formed between the outlet and the through-hole of the air flow sensor is also the flow velocity of air passing through the inlet and the outlet of the air flow sensor. The flow rate of air passing through the gap and the flow rate of air passing through the inlet and outlet have a certain relationship. Therefore, using an air flow sensor that detects the flow rate of air flowing in from the inlet, based on the flow rate of air flowing in from the inlet detected by the air flow sensor and the flow rate of air passing through the gap corresponding thereto, The flow rate of air flowing through the through hole can be detected.

  In addition, even if the air pressure difference in the space sandwiching the through hole is large, all the air flowing into the through hole is not configured to flow into the air volume sensor. As compared with the configuration in which is provided without a gap, the flow velocity of the air flowing into the inlet of the air volume sensor can be reduced. Therefore, even when the air pressure difference in the space sandwiching the through hole of the sensor mounting wall becomes large, the flow rate of the air flowing through the through hole is changed without changing the configuration of the air flow sensor and the size of the through hole. It is possible to detect with high accuracy.

  According to a second aspect of the present invention, in the sensor mounting structure according to the first aspect, the outlet and the through hole face each other on a straight line extending in a direction in which the through hole passes through the sensor mounting wall. It is characterized by that.

  According to the above invention, since the outlet and the through hole face each other on the straight line extending in the direction in which the through hole passes through the sensor mounting wall, the air flows into the through hole through the inlet and outlet of the air flow sensor. The air flow can be made smooth.

  According to a third aspect of the present invention, in the sensor mounting structure according to the first or second aspect, the air volume sensor includes a heat generating portion that generates heat, and a thermopile provided around the heat generating portion. A flow rate of air flowing into the inflow port is detected based on a voltage output from the thermopile.

  According to the above invention, the air volume sensor detects the flow rate of the air flowing into the inflow port of the air volume sensor based on the voltage output from the thermopile provided around the heat generating portion. The air volume sensor having such a configuration can be configured using MEMS (Micro-Electro-Mechanical Systems). Therefore, in the device provided with the sensor mounting structure, it is possible to reduce the size of the device or reduce the installation space of the air volume sensor.

  Invention of Claim 4 is provided with the sensor attachment structure as described in any one of Claims 1-3, and the duct which forms the flow path of air, The said sensor attachment wall is formed by the said duct, An internal space of the duct through which air flows is the second space, and the air volume sensor is provided outside the duct.

  According to the said invention, the flow volume of the air which flows into the through-hole of a duct is detected with the air volume sensor attached with respect to the duct, and the fluctuation | variation of the pressure of the air in the internal space of a duct can be detected.

According to a fifth aspect of the invention, in the projection display apparatus according to the fourth aspect of the invention, an air filter is provided that is located upstream of the through hole in the air flow.
According to the above invention, the projection display apparatus includes the air filter positioned upstream of the air flow from the through hole of the duct. According to such a configuration, the air flow sensor for detecting the flow rate of the air flowing through the through hole detects the fluctuation of the air pressure in the internal space of the duct and determines the degree of clogging of the air filter. Is possible.

  According to the present invention, even when the air pressure difference in the space sandwiching the through hole of the sensor mounting wall becomes large, the air flow sensor flows through the through hole without changing the configuration and the size of the through hole. It becomes possible to detect the air flow rate with high accuracy.

1 is a perspective view showing an external appearance of a projection display apparatus according to an embodiment of the present invention. Sectional drawing which shows typically the internal structure about the projection type video display apparatus of the embodiment. The block diagram which shows typically the structure of the sensor attachment structure with which the projection type video display apparatus of the embodiment is provided. The block diagram which shows typically the system comprised by the air volume sensor with which the projection type video display apparatus of the embodiment is provided. The block diagram which shows typically the structure of the sensor attachment structure of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, the dashed-dotted arrow in the figure shows the flow of air.
As shown in FIG. 1, the projection display apparatus according to this embodiment capable of projecting and displaying an image on a plane such as a screen or a wall is a video projector 1 (hereinafter referred to as “projector”) that displays an image based on an image signal. 1 ").

  The projector 1 includes a housing 10 that stores optical components, electronic components, and the like. The projector 1 displays an image on an image display surface (not shown) facing the projector 1 by projecting image light from the opening 11 provided in the housing 10 by the projection lens 21.

  The housing 10 is provided with an air inlet 12 for sucking air from the outside of the projector 1 and an air outlet (not shown) for discharging air from the inside of the projector 1 to the outside. The inlet 12 is provided with a lattice member 13 that prevents large foreign matter from entering the projector 1.

  The projector 1 includes an optical component such as a discharge lamp (not shown) as a cooling target component that is cooled by air cooling. The air sucked into the projector 1 is blown as cooling air to the parts to be cooled.

  The housing 10 is provided with a notification unit 22 that performs a notification operation. The notification unit 22 is a light emitting unit that emits light, and includes, for example, an LED (Light Emitting Diode). When the flow rate of air sucked into the projector 1 through the air inlet 12 decreases, the notification unit 22 notifies that by emitting light.

The internal configuration of the projector 1 will be described with reference to FIG.
Inside the projector 1 are an air filter 31 that captures dust in the air, a duct 32 that forms a flow path of cooling air that flows to the component to be cooled, and a cooling fan 33 that blows cooling air to the component to be cooled. Is provided.

  The air filter 31 is provided so as to cover the openings of the lattice member 13 and the duct 32. The duct 32 partitions the space inside the projector 1, that is, the space inside the housing 10. Of the spaces partitioned by the duct 32, the external space of the duct 32 is defined as a first space S1, and the internal space of the duct 32 is defined as a second space S2. The cooling fan 33 sucks air from the outside of the projector 1 through the duct 32.

  When the cooling fan 33 is driven, the pressure in the second space S2 is lower than the outside of the projector 1, so that air is sucked into the projector 1 through the air filter 31, and the air flows into the second space. At this time, dust contained in the air is captured by the air filter 31. Air sucked into the projector 1 is guided to the cooling fan 33 by the duct 32. Then, the cooling air blown from the cooling fan 33 is guided to the component to be cooled through another duct (not shown).

  The duct 32 is formed with a through hole 32A that communicates the first space S1 and the second space S2. When the cooling fan 33 is driven, the pressure in the second space S2 is lower than that in the first space S1, so that air is sucked into the second space S2 from the first space S1 through the through hole 32A.

  An air volume sensor 40 for detecting the flow rate of the air flowing through the through hole 32A is attached to the duct 32 which is a sensor mounting wall. Hereinafter, the sensor mounting structure provided in the projector 1 will be described with reference to FIG.

  In the sensor mounting structure in which the air volume sensor 40 is attached to the duct 32, the air volume sensor 40 is provided in the first space S <b> 1 that is a space outside the duct 32. The air volume sensor 40 is brought into close contact with a sensor mounting portion 32B provided in the vicinity of the through-hole 32A, and is fixed to the duct 32 using screws (not shown).

  The air volume sensor 40 has an inlet 41 through which air flows from the first space S1 and an outlet 42 through which air flows into the air volume sensor 40 from the inlet 41. The air volume sensor 40 detects the flow rate of the air flowing into the air volume sensor 40, that is, the air flowing into the inlet 41. The air that flows out from the outflow port 42 flows into the through hole 32A.

  Inside the air volume sensor 40, a flow sensor element (not shown) including a temperature sensor is provided. The flow sensor element is an integrated circuit including a fine mechanical structure in which an insulating thin film sandwiching a heater and a thermopile is provided on a base. The thermopile is provided around the heater that generates heat. The voltage output from the thermopile changes according to the temperature distribution that changes as air flows in the vicinity of the insulating thin film of the flow sensor element. The air volume sensor 40 detects the flow rate of air at the inlet 41 based on the voltage output from the thermopile.

  The sensor attachment portion 32 </ b> B provided with the air volume sensor 40 is a portion in which a part of the duct 32 is protruded toward the first space S <b> 1, that is, toward the outside of the duct 32. Accordingly, a step is formed between the outer surface of the duct 32 in which the through hole 32A is formed and the outer surface of the duct 32 in the sensor mounting portion 32B.

  The air volume sensor 40 provided outside the duct 32 is provided such that a gap C is provided between the outlet 42 and the through hole 32A. In the present embodiment, on the straight line in which the through hole 32A extends in the direction passing through the duct 32, the outlet 42 and the through hole 32A face each other with a space therebetween. The air volume sensor 40 does not completely cover the through hole 32A, and the first space S1 and the through hole 32A communicate with each other through the gap C. The gap C is a space in which air flows into the through hole 32A through the gap C when an air pressure difference occurs in the first space S1 and the second space S2.

  As described above, when an air pressure difference occurs in the first space S1 and the second space S2, air flows into the through hole 32A from both the outlet 42 and the gap C according to the pressure difference. The outlet 42 is provided at a distance from the through hole 32A. The projector 1 determines the degree of clogging of the air filter 31 using the air volume sensor 40 in the sensor mounting structure.

With reference to FIG. 4, the system configuration of the projector 1 using the air volume sensor 40 will be described.
The projector 1 includes a control unit 51 that controls the notification unit 22 and a storage unit 52 that stores information such as a program executed by the control unit 51.

  The control unit 51 is configured by an integrated circuit. The air volume detection result output by the air volume sensor 40 is input to the control unit 51. As a result of the air volume detection, the control unit 51 receives a voltage at which the thermopile constituting the air volume sensor 40 is output. Based on this voltage, the control unit 51 determines the flow rate of air flowing into the through hole 32A from the first space S1 through the inlet 41 and the outlet 42 of the air volume sensor 40.

  The storage unit 52 is configured by a readable / writable nonvolatile memory. The storage unit 52 stores information on the flow rate of air flowing through the gap C according to the flow rate of air flowing into the through-hole 32A through the outlet 42. As the flow velocity of the air flowing through the through hole 32A increases, the flow velocity of the air passing through the gap C formed between the outlet 42 of the air volume sensor 40 and the through hole 32A also increases the inlet 41 and the outlet 42 of the air volume sensor 40. The flow rate of the air passing through the air gap increases, and the flow rate of the air passing through the gap C and the flow rate of the air passing through the inflow port 41 and the outflow port 42 have a certain relationship. Therefore, information indicating the relationship between the flow rate of air flowing into the through hole 32A through the outlet 42 and the flow rate of air flowing into the through hole 32A through the gap C is stored. Such information can be obtained by an experiment, and the information obtained by the experiment is stored in the storage unit 52 in advance.

  Based on the information stored in the storage unit 52, the control unit 51 of the present embodiment passes through the gap C formed between the outlet 42 of the air volume sensor 40 and the through hole 32A, and thus the first space S1. The flow rate of the air flowing into the through-hole 32A is determined. That is, the control unit 51 determines the air flowing into the through hole 32A based on the flow rate of air flowing into the through hole 32A from the first space S1 and the information on the flow rate of air flowing through the gap C according to the flow rate of this air. Detect the flow rate.

  The control unit 51 determines that the degree of clogging of the air filter 31 located upstream of the through hole 32A is higher than that of the through hole 32A when the detected flow rate of the air flowing through the through hole 32A is greater than or equal to a predetermined value. When the flow rate of air flowing through the through hole 32A is equal to or greater than a predetermined value, the degree of clogging of the air filter 31 is large and the flow rate of air sucked into the projector 1 through the air inlet 12 is reduced. Therefore, the control unit 51 replaces or cleans the air filter 31 when the flow rate of air flowing through the through hole 32A is equal to or higher than a predetermined value, that is, when the flow rate of air sucked into the projector 1 through the intake port 12 decreases. In order to prompt, the notification unit 22 performs a notification operation.

The operation of the present invention will be described.
When the degree of clogging of the air filter 31 increases and an air pressure difference occurs between the first space S1 and the second space S2, the air filter 31 passes through the gap C from the first space S1 according to the pressure difference. Air flows into the through hole 32A, and air flows from the first space S1 into the through hole 32A through the inflow port 41 and the outflow port 42. At this time, the control unit 51 detects the flow rate of the air flowing through the through hole 32 </ b> A based on the air volume detection result input from the air volume sensor 40 and the information stored in the storage unit 52. Then, the flow rate of air passing through the air filter 31 is detected based on the flow rate of air flowing through the through hole 32A.

According to this embodiment, the following effects can be obtained.
(1) Using the air volume sensor 40 that detects the flow rate of air flowing in from the inlet 41, the flow rate of air flowing in from the inlet 41 detected by the air volume sensor 40, and the flow rate of air passing through the gap C corresponding to this Based on the above, the flow rate of the air flowing through the through hole 32A can be detected. Further, even when the air pressure difference in the spaces S1 and S2 sandwiching the through hole 32A becomes large, the air volume sensor 40 is not configured so that all of the air flowing into the through hole 32A flows into the air volume sensor 40. Compared with the configuration in which the outlet 42 and the through hole 32A are provided without a gap, the flow velocity of the air flowing into the inlet 41 of the air volume sensor 40 can be reduced. Therefore, even when the air pressure difference in the spaces S1 and S2 sandwiching the through hole 32A of the duct 32 becomes large, the configuration of the air volume sensor 40 and the size of the through hole 32A are not changed, and the through hole 32A. It is possible to accurately detect the flow rate of the air flowing in the air.

  FIG. 5 shows a sensor mounting structure of a comparative example to be compared with the present invention. In the sensor mounting structure shown in FIG. 5, the through hole 32A is formed in the sensor mounting portion 32B to which the air volume sensor 40 is in close contact, and the through hole 32A is covered by the air volume sensor 40. Therefore, the gap C shown in FIG. It is not formed between the first space S1 and the through hole 32A. Therefore, even if the flow rate of the air flowing through the through hole 32A shown in FIGS. 3 and 5 is the same, the flow rate and flow velocity of the air flowing into the inlet 41 shown in FIG. 5 are large, and the through hole 32A shown in FIG. The flow rate of flowing air may not be detected with high accuracy. In addition, by providing the air volume sensor 40 in a portion where the air pressure difference between the first space S1 and the second space S2 is small, it is possible to accurately detect the air flow rate with the sensor mounting structure shown in FIG. It takes time and effort to find a portion having a small air pressure difference between the first space S1 and the second space S2.

  (2) Since the outflow port 42 and the through hole 32A face each other on a straight line extending in a direction in which the through hole 32A passes through the duct 32, the through hole 32A passes through the inflow port 41 and the outflow port 42 of the air volume sensor 40. The flow of air flowing into the can be made smooth.

  (3) The air volume sensor 40 detects the flow rate of the air that has flowed into the inlet 41 of the air volume sensor 40 based on the voltage output from the thermopile provided around the heater that is the heat generating portion. The air volume sensor 40 having such a configuration can be configured using MEMS (Micro-Electro-Mechanical Systems). Therefore, in the projector 1 that is an apparatus having the sensor mounting structure, it is possible to reduce the size of the projector 1 or reduce the installation space of the air volume sensor 40.

  (4) The flow rate of air flowing through the through hole 32A of the duct 32 is detected by the air volume sensor 40 attached to the duct 32, and the fluctuation of the air pressure in the second space S2 that is the internal space of the duct 32 is detected. Can be detected.

  (5) The projector 1 includes an air filter 31 located on the upstream side of the flow of cooling air from the through hole 32 </ b> A of the duct 32. According to such a configuration, the air volume sensor 40 for detecting the flow rate of the air flowing through the through hole 32A detects the fluctuation of the air pressure in the second space S2, and the degree of clogging of the air filter 31 is determined. It is possible to judge.

  The present invention is not limited to the above embodiment, and various design changes can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention. For example, the above embodiment may be modified as follows, or the following modifications may be combined.

  In the above embodiment, the air volume sensor 40 is configured to detect the air flow rate based on the voltage output from the thermopile provided around the heat generating portion. However, the air volume sensor detects the air flow rate by other methods. A sensor can also be used. That is, the air volume sensor 40 is an integrated circuit including a fine mechanical structure having a heater and a thermopile, but an air volume sensor having a configuration other than this can also be used. An air volume sensor that detects the flow rate of air per predetermined time can also be used. Such an air volume sensor is generally called a wind speed sensor because the air flow rate per predetermined time indicates the wind speed.

  In the above embodiment, the outflow port 42 and the through hole 32A face each other on the straight line extending in the direction in which the through hole 32A passes through the duct 32, but the straight line extends in the direction in which the through hole 32A passes through the duct 32. The positions of the outlet 42 and the through hole 32A can be shifted.

  In the above embodiment, the sensor mounting wall is formed by the duct 32, but parts other than the duct 32 can be used as the sensor mounting wall. That is, the use of the sensor mounting wall is not limited to the use of forming an air flow path. Further, the position where the air volume sensor is provided can be changed.

  -Although the sensor attachment structure of the said embodiment is a structure with which the projector 1 is provided, apparatuses other than the projector 1 can also be provided with the said sensor attachment structure. For example, an air cleaner or an air conditioner may have the sensor mounting structure.

  DESCRIPTION OF SYMBOLS S1 ... 1st space, S2 ... 2nd space, C ... Gap, 1 ... Video projector (projection type image display apparatus), 10 ... Housing, 11 ... Opening part, 12 ... Intake port, 13 ... Lattice member, 21 ... Projection lens, 22 ... notification unit, 31 ... air filter, 32 ... duct (sensor mounting wall), 32A ... through hole, 32B ... sensor mounting unit, 33 ... cooling fan, 40 ... air volume sensor, 41 ... inlet, 42 ... Outflow port, 51 ... control unit, 52 ... storage unit.

Claims (5)

A sensor mounting structure in which an air volume sensor for detecting a flow rate of air flowing through the through hole is mounted on a sensor mounting wall in which the through hole is formed,
The sensor mounting wall partitions the first space and the second space sandwiching the through hole, and the sensor is provided in the first space,
The air volume sensor has an inflow port through which air flows from the first space and an outflow port from which air flows into the air flow sensor from the inflow port, and detects the flow rate of air flowing into the inflow port. And
The air volume sensor is provided so that a gap is provided between the outlet and the through hole, and the first space and the through hole communicate with each other through the gap.
When an air pressure difference occurs between the first space and the second space, the outlet port is configured so that air flows into the through hole from both the outlet port and the gap according to the pressure difference. Is provided at a distance from the through hole. The sensor mounting structure according to claim 1, wherein the outlet and the through hole face each other on a straight line extending in a direction in which the through hole passes through the sensor mounting wall. The air volume sensor has a heat generating part for generating heat and a thermopile provided around the heat generating part, and detects a flow rate of air flowing into the inflow port based on a voltage output from the thermopile. The sensor mounting structure according to claim 1 or 2. The sensor mounting structure according to any one of claims 1 to 3, and a duct that forms an air flow path,
The duct is formed with the sensor mounting wall,
An internal space of the duct through which air flows is the second space, and the air volume sensor is provided outside the duct. The projection image display apparatus according to claim 4, further comprising an air filter positioned upstream of the through hole in the air flow.