JP2020019458A - Fogging prevention device - Google Patents

Abstract

To provide a fogging prevention device that can be readily manufactured.SOLUTION: A fogging prevention device includes: a casing storing an imaging device for capturing an image through a transmissive member that transmits light therethrough, and fitted to the transmissive member; a blower device; a duct having a supply port for supplying a gas when the blower device is operated and a discharge port opened inside the casing and discharging the gas, and provided integrally with the casing; and a heating device for heating the gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fogging prevention device for an imaging device that captures an outdoor image through a transparent member such as glass.

  2. Description of the Related Art Conventionally, an imaging device that captures the outside of a window through a window glass has been used by an imaging device mounted inside a window glass of a car, a train, an airplane, a building, or the like.

  If the temperature outside the room is lower than the temperature inside the room where the imaging device is placed, moisture in the room may condense and adhere to the window glass, and the window glass may become cloudy. When the window glass becomes cloudy, it becomes impossible to clearly image the outside of the room through the window glass from the imaging device. Therefore, in a casing for fixing the imaging device to the window glass (that is, in the internal space of the casing), there is provided a fogging prevention device that heats the inside of the window glass to prevent or remove fogging of the window glass. Various proposals have been made (for example, see Patent Document 1).

JP-A-2002-341432

  However, since the internal space of the casing accommodating the imaging device is narrow, the conventional fogging prevention device has a problem that it takes time and effort to provide the components of the fogging prevention device in the internal space of the casing, and cannot be easily manufactured.

  The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a fogging prevention device which can be easily manufactured.

  In order to solve the above-described conventional problems, the fogging prevention device of the present invention accommodates an imaging device that captures an image through a transparent member that transmits light, a casing attached to the transparent member, a blower, A supply port to which gas is supplied by the operation of the blower, a discharge port opened in the casing and discharging the gas, a duct provided integrally with the casing, and a heating device for heating the gas And.

  According to the present invention, a fogging prevention device can be easily manufactured.

1 is a schematic longitudinal sectional view of a fogging prevention device according to an embodiment of the present invention. The typical longitudinal section of the important section of the fogging prevention device of one embodiment of the present invention. The typical perspective view of the principal part of the fogging prevention device of one embodiment of the present invention. The typical exploded perspective view of the principal part of the fogging prevention device of one embodiment of the present invention. FIG. 1 is a schematic plan view of a planar heater according to an embodiment of the present invention. 1 is a schematic perspective view of a piezoelectric blower according to an embodiment of the present invention. Schematic bottom view of a piezoelectric blower according to one embodiment of the present invention Functional block diagram of a control system of the fogging prevention device of one embodiment of the present invention It is a figure for explaining an operation effect of a fogging prevention device of one embodiment of the present invention, and a typical longitudinal section of a fogging prevention device. It is a figure for explaining an operation effect of a fogging prevention device of one embodiment of the present invention, and a longitudinal section of a typical fogging prevention device. The typical perspective view of the principal part in the modification of the fogging prevention device of one embodiment of the present invention.

  Hereinafter, a fogging prevention device according to an embodiment of the present invention will be described with reference to the drawings. The embodiments described below are merely examples, and do not exclude various modifications and application of techniques not explicitly described in the following embodiments. In addition, each configuration of the embodiment can be variously modified and implemented without departing from the spirit thereof. Furthermore, each configuration of the embodiment can be selected as needed or can be appropriately combined.

  In each of the following embodiments, an example will be described in which the fogging prevention device of the present invention is used in a vehicle-mounted camera that captures an image of the outside of a vehicle through a windshield (transmissive member) of the vehicle.

  Hereinafter, in the fogging prevention device, the windshield side to which the fogging prevention device is attached is referred to as front, and the opposite side is referred to as rear. Further, the left and right are determined based on the case where the user looks forward from behind.

  In all the drawings for describing the embodiments, the same elements are denoted by the same reference numerals in principle, and the description thereof may be omitted.

[1. Constitution]
The configuration of the fogging prevention device in the present embodiment will be described with reference to FIGS. FIG. 1 is a schematic longitudinal sectional view of a fogging prevention device according to one embodiment of the present invention. FIG. 2 is a schematic longitudinal sectional view of a main part of the fogging prevention device according to one embodiment of the present invention. FIG. 3 is a schematic perspective view of a main part of the fogging prevention device according to one embodiment of the present invention. FIG. 4 is a schematic exploded perspective view of a main part of the fogging prevention device according to one embodiment of the present invention. FIG. 5 is a schematic plan view of a planar heater according to one embodiment of the present invention. FIG. 6 is a schematic perspective view of a piezoelectric blower according to one embodiment of the present invention. FIG. 7 is a schematic bottom view of the piezoelectric blower according to one embodiment of the present invention.

  The fogging prevention device 1 shown in FIG. 1 includes a casing 2, a blowing device 3, and a heating device 4.

  The casing 2 has a box shape opened forward, and includes a ceiling wall, a rear wall, a bottom wall, a left side wall, and a right side wall. The casing 2 has a front end face of a ceiling wall, a bottom wall, a left side wall, and a right side wall attached to a windshield 20 of the vehicle in close contact therewith. ) Is sealed (or substantially sealed) by the windshield 20. An in-vehicle camera 30 (imaging device) is installed in the casing inner space 2a. In the present embodiment, the vehicle-mounted camera 30 is fixed to the inner surface of the rear wall of the casing 2 at a predetermined distance above the bottom surface of the casing 2.

  In the casing 2, a flow path 5 through which air flows toward the windshield 20 by the operation of the blower 3 is formed. In the present embodiment, the flow path 5 is formed inside the bottom wall of the casing 2. In other words, the duct 5 </ b> A having the flow path 5 therein (see FIG. 2) is formed integrally and flush with the bottom wall of the casing 2. Since the flow path 5 is provided within the thickness of the bottom wall of the casing 2, the flow path 5 has a flat shape whose height is smaller than each of the front, rear, left, and right dimensions. The flow path 5 extends back and forth, and the flow path 5 is provided with an air supply port 5a that opens upward at a rear portion thereof, and an air discharge port 5b that penetrates an upper surface of a bottom wall at a front portion thereof. Is provided. In the present embodiment, the supply port 5a and the discharge port 5b are circular, but are not limited to this.

  The blower 3 supplies the air in the casing internal space 2 a to the flow path 5. Specifically, when the blower 3 is operated, the air in the casing inner space 2a is supplied to the flow path 5 from the supply port 5a, flows through the flow path 5 toward the discharge port 5b, and flows from the discharge port 5b to the windshield. In the vicinity of 20, it is discharged to the casing internal space 2a. That is, by operating the blower 3, a circulating flow of air circulating between the casing internal space 2 a and the flow path 5 is formed.

  In the present embodiment, the blower 3 is configured by a piezoelectric blower shown in FIGS. 6 and 7. Therefore, hereinafter, the blower 3 is also referred to as a piezoelectric blower 3. The piezoelectric blower 3 uses piezoelectric ceramics as a driving source of air. When an AC signal is applied to the piezoelectric ceramics, the piezoelectric ceramics ultrasonically vibrate to send out air. The piezoelectric blower 3 is smaller and thinner than a general blower having an impeller, and can discharge air at a high pressure.

  The piezoelectric blower 3 will be further described. The piezoelectric blower 3 includes a suction port 3a, a discharge port 3b, and wirings 3c and 3d, and the suction port 3a and the discharge port 3b are connected to each other by a passage (not shown). The piezoelectric blower 3 has the suction port 3a directed upward and the discharge port 3b directed downward, and the discharge port 3b is inserted into the supply port 5a of the flow path 5. When an AC signal is applied from the wires 3c and 3d, the piezoelectric blower 3 sucks air in the casing internal space 2a from the suction port 3a and supplies the sucked air to the flow path 5 from the discharge port 3b.

  As shown in FIGS. 1 and 2, the heating device 4 is installed on the upper surface of the bottom wall of the casing 2 in the present embodiment. The heating device 4 is installed above the flow path 5, and extends between the supply port 5 a and the discharge port 5 b of the flow path 5 along the direction in which gas flows through the flow path 5 (flow direction). .

  When the heating device 4 is operated, the radiant heat from the heating device 4 heats the air in the casing inner space 2a and also heats the air flowing through the flow path 5 via the bottom wall. That is, the heating device 4 also functions as the heating device of the present invention and the heat radiating unit.

  In the present embodiment, the heating device 4 is configured by a planar heater shown in FIG. Therefore, hereinafter, the heating device 4 is also referred to as a planar heater 4. The planar heater 4 is composed of a base material 4a, a heating element 4b provided on the base material 4a and made of a meandering (meandering) metal foil, and wirings 4c and 4d. The heating element 4b generates heat by supplying power from the wirings 4c and 4d.

  The substrate 4a is formed from, for example, a resin film. Since the air in the flow path 5 is heated by the heating element 4b via the base material 4a, the thickness of the base material 4a is preferably 200 μm or less so that the air in the flow path 5 can be quickly heated.

  When the heating element 4b is overheated due to continuous operation, it is preferable to detect the temperature of the heating element 4b and manage the temperature of the heating element 4b based on the detection result. Alternatively, it is preferable to use a resistance heating element having a self-temperature adjusting function as the heating element 4b.

  Further, the air flowing in the flow path 5 is heated by the planar heater 4 via the upper wall 2b of the flow path 5, so that the air in the flow path 5 is also heated by the planar heater 4 via the wall 2b. It is preferable that the wall 2b be thin so that the wall 2b can be heated effectively. In addition, it is preferable to provide a material having high heat insulation such as a foam so that heat does not escape from the flow channel 5 on the wall surface excluding the wall 2b among the wall surfaces facing the flow channel 5.

  In the present embodiment, the planar heater 4 is provided outside the flow channel 5, but may be provided inside the flow channel 5, for example, on the lower surface of the wall 2b. In this case, the air in the casing internal space 2a is heated by radiant heat from the upper surface of the wall 2b. Therefore, the upper surface of the wall 2b constitutes the heat radiator of the present invention.

  Further, in the present embodiment, the discharge port 5b of the flow path 5 is formed in a circular shape and only one is provided at the center of the bottom wall of the casing 2, but the shape, arrangement and number of the discharge ports 5b are not limited to this. Not done. The shape, arrangement, and number of the discharge ports 5b are appropriately set according to the shape of the vehicle-mounted camera 30, the position of the vehicle-mounted camera 30 in the casing 2, and the like.

[2. control]
Control of the fogging prevention device according to one embodiment of the present invention will be described with reference to FIGS. 8, 9A, and 9B. FIG. 8 is a functional block diagram of a control system of the fogging prevention device according to the embodiment of the present invention. 9A and 9B are views for explaining the operation and effect of the fogging prevention device according to one embodiment of the present invention, and are schematic longitudinal sectional views of the fogging prevention device.

  The operation of the fogging prevention device 1 is controlled by a control device 10 of a vehicle in which the fogging prevention device 1 is installed (hereinafter referred to as “the relevant vehicle”). Hereinafter, a specific description will be given.

  The vehicle is provided with a first temperature sensor 11 for detecting the temperature inside the vehicle compartment and a second temperature sensor 12 for detecting the temperature outside the vehicle. The detection result of the first temperature sensor 11 and the detection result of the second temperature sensor 12 are transmitted to the control device 10, respectively.

  The control device 10 obtains a temperature difference ΔT (= Tin−Tout) between the temperature Tin inside the vehicle compartment and the outside Tout based on the detection result of the first temperature sensor 11 and the detection result of the second temperature sensor 12. When this temperature difference ΔT is larger than threshold value T1 (ΔT> T1), control device 10 determines that fogging of windshield 20 is expected, and starts operation of fogging prevention device 1 (fogging prevention operation). That is, the operation of both the piezoelectric blower 3 and the planar heater 4 is started.

  By the operation of the piezoelectric blower 3, as shown by an arrow A1 in FIG. 9A, a strong circulating flow of high-temperature air (hot air) heated by the planar heater 4 is formed in the casing internal space 2a. Therefore, immediately after the start of operation of the fogging prevention device 1, high-temperature air flows through the windshield 20, and the inner surface of the windshield 20 (that is, the surface on the casing internal space 2 a side) radiates heat from the planar heater 4. In addition to this, the air is rapidly heated by the high-temperature air to increase the temperature.

  The control device 10 has a timer function for measuring an elapsed time t from when the operation of the fogging prevention device 1 is started. If the elapsed time t measured by the timer function exceeds the predetermined time t0 (t> t0), the control device 10 determines that the inner surface of the windshield 20 has been heated to a temperature at which no dew condensation occurs on the inner surface, and The operation of the blower 3 is stopped.

  Thereafter, as shown in FIG. 9B, the temperature of the casing internal space 2a and the temperature of the inner surface of the windshield 20 are reduced by the gentle circulation of high-temperature air indicated by an arrow A2 caused by natural convection and the radiation from the planar heater 4. Is held.

  Control device 10 stops fogging prevention device 1 when temperature difference ΔT between vehicle interior temperature Tin and vehicle exterior temperature Tout becomes smaller than threshold value T2 (ΔT <T2). That is, when the planar heater 4 is stopped and the piezoelectric blower 3 is operating, the piezoelectric blower 3 is stopped.

  Note that a control device that controls the operation of the fogging prevention device 1 may be provided separately from the control device 10 of the vehicle.

[3. Action / Effect]
The operation and effect of the fogging prevention device according to one embodiment of the present invention will be described.

  (1) Since the duct 5A is integrally formed inside the casing 2 as shown in FIG. 2, the fogging prevention device is compared with a case where a duct separate from the casing 2 is provided in the casing internal space 2a. 1 can be easily manufactured.

  (2) Since the air sent by the blower 3 is heated by the heater 4, the high-temperature air heated by the heater 4 can quickly reach the windshield 20 to heat the windshield 20. Therefore, fogging of the windshield 20 can be quickly prevented and removed.

  (3) Among the heat generated from the heating device 4, the air that flows through the flow path 5 is heated by the heat that is transmitted to the outside of the casing 2, that is, the heat that is released to the outside of the casing 2 if there is no flow path 5. . Therefore, the heat generated by the heating device 4 can be effectively used without waste.

  (4) The heating device 4 is provided in the duct 5A, and the planar heater constituting the heating device 4 extends along the flow direction of the air flowing through the flow path 5 in the duct 5A. This makes it possible to lengthen the time during which the air flowing through the flow path 5 is heated by the heating device 4. Therefore, the temperature of the air can be quickly raised, and the fogging of the windshield 20 can be promptly prevented and removed by the high-temperature air.

  (5) Since both the supply port 5a and the discharge port 5b of the duct 5A are open to the casing internal space 2a, a circulating flow of air is formed in the casing internal space 2a. Therefore, the air in the casing internal space 2a is repeatedly heated each time it flows through the flow path 5, and the casing internal space 2a is maintained at a high temperature as compared with a case where low-temperature air is sucked from outside the casing 2 and heated. it can.

  (6) Since the supply port 5a and the discharge port 5b of the duct 5A are open to the same upper side, the air blown up from the discharge port 5b by the operation of the blower 3 causes the supply port to open upward. The mouth 5a sucks downward. As a result, a circulating flow flowing from the discharge port 5b to the supply port 5a along the inner surface of the windshield 20 and the inner surface of the casing 2 can be positively formed, and the inner surface of the windshield 20 can be entirely (or substantially entirely). It can be heated effectively. Therefore, fogging of the windshield 20 can be prevented and removed over the entire (or substantially the entire) windshield 20.

  (7) In addition to the high-temperature air discharged from the duct 5A, the windshield 20 can be heated by the radiant heat of the heat radiating portion (heating device 4) provided in the duct 5A. Can be prevented and removed.

  (8) Immediately after the fogging prevention device 1 starts the fogging prevention operation, the blowing device 3 and the heating device 4 are operated. Thus, the windshield 20 can be quickly heated by the forced circulation of the high-temperature air, and the fogging of the windshield 20 can be quickly prevented and removed. After the casing inner space 2a reaches a high-temperature atmosphere in which the windshield 20 does not fog, the blower 3 is stopped and only the heater 4 is operated. This makes it possible to maintain the casing internal space 2a in a high-temperature atmosphere in which no fogging occurs in the windshield 20, while suppressing power consumption of the fogging prevention device 1.

  (9) A small and thin piezoelectric blower is used for the blower 3 compared to a general blower. Therefore, it can be easily installed even in the narrow casing internal space 2a, and the influence on the circulation flow of the casing internal space 2a can be minimized.

[4. Modification]
A modification of the fogging prevention device according to the embodiment of the present invention will be described.
(1) A modification of the fogging prevention device will be described with reference to FIG. FIG. 10 is a schematic perspective view of a main part in a modification of the fogging prevention device according to one embodiment of the present invention. In FIG. 10, for convenience, the windshield 20 and the ceiling wall of the casing 2 are removed.

  The configuration shown in FIG. 10 is provided in addition to the above embodiment. In the configuration shown in FIG. 10, a duct 5 </ b> B having an air flow path inside is integrally provided on the inner surface of the side wall of the casing 2. The duct 5B has a stepped shape that protrudes toward the casing internal space 2a. A plurality of discharge ports 5c for discharging high-temperature air toward the windshield are provided on the front end face of the duct 5B in a vertically arranged manner. These discharge ports 5c communicate with the flow path 5 (see FIG. 1) of the bottom wall of the casing 2 via communication paths provided on the side wall and the bottom wall of the casing 2.

  With such a configuration, high-temperature air is discharged from the discharge ports 5c vertically arranged on the side wall of the casing 2, and the high-temperature air heats the windshield from the upper edge to the lower edge of the casing 2. it can.

  (2) The heating device is not limited to the above embodiment. For example, a plurality of coil heaters may be provided on the inner surface or the outer surface of the duct 5A along the flow direction of the air flowing through the duct 5A, and a heating device may be configured by these coil heaters. Even with such a configuration, the temperature of the air flowing through the flow path 5 in the duct 5A can be quickly increased, and the fogging of the windshield 20 can be promptly prevented and removed by the high-temperature air.

  (3) The fogging prevention device of the present invention can be used not only for a vehicle-mounted camera but also for various imaging devices, and can be applied to, for example, a surveillance camera.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a fogging prevention device, and its industrial applicability is high.

DESCRIPTION OF SYMBOLS 1 Fogging prevention device 2 Casing 2a Internal space 2b Wall 3 Blower (piezoelectric blower)
3a suction port 3b discharge port 3c, 3d wiring 4 heating device (plane heater)
Reference Signs List 4a Base material 4b Heating element 4c, 4d Wiring 5 Flow path 5A, 5B Duct 5a Supply port 5b, 5c Discharge port 10 Controller 11 First temperature sensor 12 Second temperature sensor 20 Wind shield (permeable member)
30 In-vehicle camera

Claims (8)

A casing that houses an imaging device that captures an image through a transparent member that transmits light, and is attached to the transparent member,
A blower,
A supply port to which gas is supplied by the operation of the blower, and a discharge port that opens into the casing and discharges the gas, and is provided integrally with the casing,
A fogging prevention device comprising: a heating device for heating the gas. The fogging prevention device according to claim 1, wherein the heating device is provided in the duct along a flow direction in which the gas flows in the duct. The fogging prevention device according to claim 2, wherein the heating device is a planar heater extending along the flow direction. The fogging prevention device according to any one of claims 1 to 3, wherein the supply port is opened in the casing. The fogging prevention device according to claim 4, wherein the discharge port and the supply port open in the same direction. The fogging prevention device according to any one of claims 1 to 5, wherein the duct has a heat radiating portion that radiates heat outside the duct. When the elapsed time from the start of the fogging prevention operation is within a predetermined time, the heating device and the blowing device are operated, and when the elapsed time exceeds the predetermined time, the blowing device is stopped, while the heating is stopped. 7. An anti-fogging device according to claim 6, which maintains operation of the device. The fogging prevention device according to any one of claims 1 to 7, wherein the blower is a piezoelectric blower.

Images