JP7101074B2 - Anti-fog device - Google Patents

Description

The present invention relates to an anti-fog device for an image pickup device that images an outdoor image through a transparent member such as glass.

Conventionally, an image pickup device that images the outside through a window glass by an image pickup device attached to the inside of a window glass of an automobile, a train, an airplane, a building, or the like has been used.

If the temperature outside the room is lower than the temperature inside the room where the image pickup device is placed, the humidity inside the room may condense and adhere to the window glass, causing the window glass to become cloudy. If the window glass becomes cloudy, it will not be possible to clearly image the outside of the room through the window glass from the image pickup device. Therefore, in the casing for fixing the image pickup device to the window glass (that is, the internal space of the casing), an anti-fog device that heats the indoor side of the window glass to prevent or remove the fogging of the window glass is provided. Various proposals have been made (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2002-341432

However, since the internal space of the casing accommodating the image pickup device is narrow, the conventional anti-fog device has a problem that it takes time and effort to provide the components of the anti-fog device in the internal space of the casing and cannot be easily manufactured.

The present invention has been devised to solve such a problem, and an object of the present invention is to provide an anti-fog device that can be easily manufactured.

In order to solve the above-mentioned conventional problems, the anti-fog device of the present invention accommodates an image pickup device that takes an image through a transparent member that transmits light, and has a casing attached to the transparent member, a blower device, and the above. A duct that has a supply port to which gas is supplied by the operation of a blower device, a discharge port that opens in the casing and discharges the gas, and a duct integrally provided in the casing, and a heating device that heats the gas. When the elapsed time from the start of the anti-fog operation is within a predetermined time, the heating device and the blower are operated, and when the elapsed time exceeds the predetermined time, the blower is stopped. On the other hand, the operation of the heating device is maintained .

According to the present invention, the anti-fog device can be easily manufactured.

Schematic vertical cross-sectional view of the anti-fog device according to the embodiment of the present invention. Schematic vertical sectional view of a main part of the anti-fog device according to the embodiment of the present invention. Schematic perspective view of the main part of the anti-fog device according to the embodiment of the present invention. Schematic exploded perspective view of the main part of the anti-fog device according to the embodiment of the present invention. Schematic plan view of the planar heater according to the embodiment of the present invention. Schematic perspective view of the piezoelectric blower according to an embodiment of the present invention. Schematic bottom view of the piezoelectric blower according to an embodiment of the present invention. Functional block diagram of the control system of the anti-fog device according to the embodiment of the present invention. It is a figure for demonstrating the operation effect of the anti-fog device of one Embodiment of this invention, and is the schematic vertical sectional view of the anti-fog device. It is a figure for demonstrating the operation effect of the anti-fog device of one Embodiment of this invention, and is the vertical sectional view of the typical anti-fog device. Schematic perspective view of a main part in a modified example of the anti-fog device according to the embodiment of the present invention.

Hereinafter, the anti-fog device according to the embodiment of the present invention will be described with reference to the drawings. The embodiments shown below are merely examples, and do not exclude the application of various modifications and techniques not specified in the following embodiments. In addition, each configuration of the embodiment can be variously modified and implemented without departing from the gist thereof. Further, each configuration of the embodiment can be selected as needed or can be combined as appropriate.

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

Further, in the following, in the anti-fog device, the windshield side to which the anti-fog device is attached is referred to as the front, and the opposite side thereof is referred to as the rear. In addition, the left and right are determined based on the case of looking from the back to the front.

In addition, in all the drawings for explaining the embodiment, the same elements may be designated by the same reference numerals in principle, and the description thereof may be omitted.

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

The anti-fog device 1 shown in FIG. 1 includes a casing 2, a blower device 3, and a heating device 4.

The casing 2 has a box shape that opens forward, and is provided with a ceiling wall, a rear wall, a bottom wall, a left side wall, and a right side wall. In the casing 2, the ceiling wall, the bottom wall, the left side wall, and the front end surface of the right side wall are attached in close contact with the windshield 20 of the vehicle, and the internal space 2a of the casing 2 (hereinafter, also referred to as “casing internal space 2a”). ) Is sealed (or substantially sealed) by the windshield 20. Further, an in-vehicle camera 30 (imaging device) is installed in the casing internal 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 distance above the bottom surface of the casing 2 by a predetermined distance.

The casing 2 is formed with a flow path 5 in which air flows toward the windshield 20 by the operation of the blower device 3. In the present embodiment, the flow path 5 is formed inside the bottom wall of the casing 2. In other words, the duct 5A (see FIG. 2) having the flow path 5 inside is formed integrally with the bottom wall of the casing 2 and flush with each other. Since the flow path 5 is provided within the thickness of the bottom wall of the casing 2, it has a flat shape in which the height dimension is smaller than the front, rear, left, and right dimensions. Further, 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 the rear portion thereof, and an air discharge port 5b that penetrates the upper surface of the bottom wall is provided at the front portion thereof. It is provided. In the present embodiment, the supply port 5a and the discharge port 5b are circular, but the present invention is not limited thereto.

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

In the present embodiment, the blower 3 is configured by the piezoelectric blowers 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 drive source for air, and 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.

Further explaining the piezoelectric blower 3, 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 communicated with each other by a passage (not shown). In the piezoelectric blower 3, the suction port 3a is directed upward, the discharge port 3b is 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 wirings 3c and 3d, the piezoelectric blower 3 sucks the 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 the gas extends along the direction (distribution direction) in which the gas flows through the flow path 5 between the supply port 5a and the discharge port 5b of the flow path 5. ..

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

In the present embodiment, the heating device 4 is configured by the 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 made of a meander-shaped (meandering shape) metal foil provided on the base material 4a, and wirings 4c and 4d. The heating element 4b generates heat by supplying electric power from the wirings 4c and 4d.

The base material 4a is formed of, 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 heated quickly.

When the heating element 4b overheats due to continuous operation, it is preferable to detect the temperature of the heating element 4b and control 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 for the heating element 4b.

Further, since 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, the air in the flow path 5 is heated by the planar heater 4 even through the wall 2b. It is preferable that the wall 2b is thin so that the wall 2b can be effectively heated. Further, among the wall surfaces facing the flow path 5, it is preferable to provide a material having high heat insulating properties such as a foam on the wall surface excluding the wall 2b so that heat does not escape from the flow path 5.

In this embodiment, the planar heater 4 is provided outside the flow path 5, but it may be provided inside the flow path 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 the radiant heat from the upper surface of the wall 2b. Therefore, the upper surface of the wall 2b constitutes the heat dissipation portion 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 in the center of the bottom wall of the casing 2, but the shape, arrangement, and number of the discharge ports 5b are 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 arrangement of the vehicle-mounted camera 30 in the casing 2, and the like, respectively.

[2. control]
The control of the anti-fog device according to the embodiment of the present invention will be described with reference to FIGS. 8, 9A and 9B. FIG. 8 is a functional block diagram of the control system of the anti-fog device according to the embodiment of the present invention. 9A and 9B are diagrams for explaining the operation and effect of the anti-fog device according to the embodiment of the present invention, and are schematic vertical sectional views of the anti-fog device.

The operation of the anti-fog device 1 is controlled by the control device 10 of the vehicle (hereinafter referred to as "the vehicle") in which the anti-fog device 1 is installed. Hereinafter, a specific description will be given.

The vehicle is provided with a first temperature sensor 11 that detects the temperature inside the vehicle and a second temperature sensor 12 that detects 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 the temperature difference ΔT (= Tin—Tout) between the temperature Tin in the vehicle interior and the temperature Tin outside the vehicle based on the detection result of the first temperature sensor 11 and the detection result of the second temperature sensor 12. When the temperature difference ΔT is larger than the threshold value T1 (ΔT> T1), the control device 10 assumes that the windshield 20 is expected to be fogged, and starts the operation of the anti-fog device 1 (anti-fog operation). That is, both the piezoelectric blower 3 and the planar heater 4 are started to operate.

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 operation of the anti-fog device 1 is started, 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 2a side) is radiated from the planar heater 4. In addition, this hot air rapidly heats and raises the temperature.

The control device 10 has a timer function for measuring the elapsed time t since the operation of the anti-fog device 1 is started. When the elapsed time t measured by this timer function exceeds the predetermined time t0 (t> t0), the control device 10 considers that the inner surface of the windshield 20 has been heated to a temperature at which dew condensation does not occur on the inner surface, and is piezoelectric. The operation of the blower 3 is stopped.

Hereinafter, 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 caused by the gentle circulating flow of high-temperature air indicated by the arrow A2 caused by natural convection and the radiation from the planar heater 4. Is retained.

The control device 10 stops the anti-fog device 1 when the temperature difference ΔT between the temperature Tin in the vehicle interior and the temperature Tout outside the vehicle becomes smaller than the 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.

A control device for controlling the operation of the anti-fog device 1 may be provided separately from the control device 10 of the vehicle.

[3. Action / effect]
The operation and effect of the anti-fog device according to the embodiment of the present invention will be described.

(1) As shown in FIG. 2, since the duct 5A is integrally formed inside the casing 2, the anti-fog device is compared with the 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 out by the blower device 3 is heated by the heating device 4, the high-temperature air heated by the heating device 4 can be quickly reached to the windshield 20 to heat the windshield 20. Therefore, fogging of the windshield 20 can be quickly prevented and removed.

(3) Of the heat generated from the heating device 4, the heat transmitted to the outside of the casing 2, that is, the heat released to the outside of the casing 2 if there is no flow path 5, heats the air flowing through the 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 prolong the time for the air flowing through the flow path 5 to be heated by the heating device 4. Therefore, the temperature of the air can be rapidly increased, and the fogging of the windshield 20 can be quickly 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, an air circulation flow 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 the case where low temperature air is sucked from the outside of the casing 2 to heat the casing. can.

(6) Since the supply port 5a and the discharge port 5b of the duct 5A are open toward the same upward direction, the air discharged upward from the discharge port 5b by the operation of the blower device 3 is supplied upward. It will be sucked downward by the mouth 5a. 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 formed over the entire surface (or substantially the entire surface). 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, so that the fogging of the windshield 20 is more effective. Can be prevented and removed.

(8) Immediately after the anti-fog device 1 starts the anti-fog operation, the blower 3 and the heating device 4 are operated. This makes it possible to quickly heat the windshield 20 by forced circulation of high-temperature air, and to quickly prevent and remove fogging of the windshield 20. Further, after the casing internal space 2a reaches a high temperature atmosphere in which the windshield 20 does not become cloudy, the blower device 3 is stopped and only the heating device 4 is operated. This makes it possible to maintain the casing internal space 2a in a high temperature atmosphere in which fogging does not occur in the windshield 20 while suppressing the consumption of the power of the fogging prevention device 1.

(9) The blower 3 uses a piezoelectric blower that is smaller and thinner than a general blower. Therefore, it can be easily installed even in the narrow casing internal space 2a, and the influence of the casing internal space 2a on the circulating flow can be minimized.

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

The configuration shown in FIG. 10 is provided in addition to the above embodiment. In the configuration shown in FIG. 10, a duct 5B 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 is convex toward the casing internal space 2a. The duct 5B is provided with a plurality of discharge ports 5c vertically arranged on the front end surface thereof to discharge high-temperature air toward the windshield. These discharge ports 5c communicate with the flow path 5 (see FIG. 1) on the bottom wall of the casing 2 via the communication passages 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 provided vertically 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. can.

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

(3) The anti-fog device of the present invention can be used not only for an in-vehicle camera but also for various image pickup devices, and can be applied to, for example, a surveillance camera.

The present invention can be applied to an anti-fog device and has high industrial applicability.

1 Anti-fog device 2 Casing 2a Internal space 2b Wall 3 Blower (piezoelectric blower)
3a Suction port 3b Discharge port 3c, 3d Wiring 4 Heating device (planar heater)
4a Base material 4b Heating element 4c, 4d Wiring 5 Flow path 5A, 5B Duct 5a Supply port 5b, 5c Discharge port 10 Control device 11 First temperature sensor 12 Second temperature sensor 20 Windshield (transparent member)
30 In-vehicle camera

Claims (7)

A casing that accommodates an image pickup device that captures images through a transmissive member that transmits light and is attached to the transmissive member.
Blower and
A duct having a supply port to which gas is supplied by the operation of the blower device and a discharge port opened in the casing to discharge the gas, and a duct integrally provided in the casing.
A heating device for heating the gas is provided .
If the elapsed time from the start of the anti-fog operation is within a predetermined time, the heating device and the blower are operated, and if the elapsed time exceeds the predetermined time, the blower is stopped while the heating is performed. Keep the device working
Anti-fog device. The anti-fog device according to claim 1, wherein the heating device is provided in the duct along a distribution direction in which the gas flows in the duct. The anti-fog device according to claim 2, wherein the heating device is a planar heater extending along the distribution direction. The anti-fog device according to any one of claims 1 to 3, wherein the supply port opens in the casing. The anti-fog device according to claim 4, wherein the discharge port and the supply port open in the same direction as each other. The anti-fog device according to any one of claims 1 to 5, wherein the duct has a heat radiating portion that dissipates heat to the outside of the duct. The anti-fog device according to any one of claims 1 to 6 , wherein the blower is a piezoelectric blower.

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