JP7007315B2 - Surveillance cameras and methods for suppressing condensation on surveillance cameras - Google Patents

Description

The present disclosure relates to a surveillance camera and a method for suppressing dew condensation on the surveillance camera.

Surveillance cameras designed to be installed outdoors are required to have airtightness, for example, in order to ensure waterproofness. Therefore, the moisture (that is, water vapor) contained in the air existing in the housing of the surveillance camera is difficult to move to the outside air, and dew condensation is likely to occur depending on the ambient temperature environment. In a surveillance camera, if dew condensation occurs on the light transmissive cover provided to protect the lens, the sharpness (that is, visibility) of the captured image is deteriorated.

In the image pickup device of Patent Document 1, a lens unit and a heat generating member are provided in an internal space, and the internal space is divided into a first closed space and a second closed space through an opening, and an opening. A valve member for opening and closing the portion, a detecting means for detecting the temperature of the internal space, an opening / closing means for opening / closing the valve member, and a control means for controlling the opening / closing operation of the valve member by the opening / closing means are provided. This image pickup device can acquire a high-definition image in a short time with a simple structure when driven in a low temperature environment.

Japanese Unexamined Patent Publication No. 2017-200109

However, in the image pickup apparatus of Patent Document 1, the internal space of the camera body is divided into a first closed space and a second closed space. When the temperature drops to a temperature at which dew condensation is likely to occur, the heater is driven to limit and heat only the first enclosed space to suppress dew condensation. On the other hand, when it becomes necessary to cool the image pickup device, the drive of the heater is stopped and the blower fan is driven. As a result, air flows between the first closed space and the second closed space, the air in the internal space of the camera body is agitated, and the heat inside the camera body is dissipated. For this reason, air containing water vapor cannot be discharged from the internal space of the sealed camera body, and there is room for improvement in that the suppression of dew condensation is insufficient. In addition, suppressing dew condensation only by driving the heater leads to an increase in running cost.

The present disclosure has been devised in view of the above-mentioned conventional circumstances, and suppresses the increase in manufacturing cost and running cost, and suppresses dew condensation on surveillance cameras and surveillance cameras that can suppress dew condensation and icing while effectively utilizing internal heat generation. The purpose is to provide a method.

The present disclosure comprises a camera unit having a lens, a housing unit having an opening facing the light incident surface of the lens to support the camera unit, and surrounding the camera unit with a gap, and the lens. A translucent cover portion that is attached to the opening and seals the housing portion, a fan that is arranged in the gap and circulates air in the gap between the cover portion, and the above. A vent hole formed in the housing portion to open the gap to the outside, a waterproof ventilation film that closes the vent, a heater provided facing the gap and heating the air, and a surface facing the gap. Provided is a surveillance camera provided with an infrared light irradiation device that emits infrared light to the outside through the cover portion and radiates light to the air.

Further, the present disclosure is a method for suppressing dew condensation on a surveillance camera, wherein the surveillance camera has a camera unit having a lens and an opening facing the light incident surface of the lens to support the camera unit. A housing portion that surrounds the camera portion across a gap, a translucent cover portion that is attached to the opening apart from the lens and seals the housing portion, and a translucent cover portion that is arranged in the gap and described above. A fan that circulates air in the gap between the cover portion, a vent that is bored in the housing portion and opens the gap to the outside, a waterproof ventilation film that closes the vent, and a surface in the gap. A heater that heats the air, an infrared light irradiation device that is provided facing the gap and emits infrared light to the outside through the cover portion and dissipates heat to the air, and the air. The control unit includes a temperature sensor that detects the temperature, and a control unit that controls the operation and stop of the fan and the heater based on the temperature detection signal from the temperature sensor and the current value of the infrared light irradiation device. Activates the heater and the fan when the detection temperature of the temperature sensor is lower than a predetermined temperature, and when the detection temperature of the temperature sensor is higher than the temperature at the start of temperature decrease, the heater and the fan. Provides a method for suppressing dew condensation on a surveillance camera.

According to the present disclosure, it is possible to suppress an increase in manufacturing cost and running cost, and to suppress dew condensation and icing while effectively utilizing internal heat generation.

Perspective view showing an example of the surveillance camera according to the first embodiment. An exploded perspective view of the surveillance camera shown in FIG. Front view of the surveillance camera shown in FIG. AA sectional view of FIG. 3 BB sectional view of FIG. A perspective view showing the mounting structure of the waterproof ventilation membrane in the surveillance camera of FIG. 1 together with an enlarged view of the main part. Enlarged view of the main part of FIG. 4 showing the flow path of air containing water vapor Perspective view showing an example of the surveillance camera according to the second embodiment. An exploded perspective view of the surveillance camera shown in FIG. Front view of the surveillance camera shown in FIG. CC sectional view of FIG. FIG. 10 is a sectional view taken along the line DD. A partially cutaway perspective view of FIG. 8 showing an air flow path. A block diagram showing an example of the main internal configuration of the surveillance cameras according to the first and second embodiments. A flowchart showing an example of the operation procedure of the dew condensation suppression method in the surveillance cameras according to the first and second embodiments. The figure which shows an example of a heater control table

Hereinafter, each embodiment in which the surveillance camera and the method for suppressing dew condensation of the surveillance camera according to the present disclosure are specifically disclosed will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters and duplicate explanations for substantially the same configuration may be omitted. This is to avoid unnecessary redundancy of the following description and to facilitate the understanding of those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
First, the surveillance camera 11 according to the first embodiment will be described with reference to FIGS. 1 to 7.

FIG. 1 is a perspective view showing an example of the surveillance camera 11 according to the first embodiment. The surveillance camera 11 according to the first embodiment is a surveillance camera having a so-called box-shaped (that is, box-shaped) housing. The installation environment of the surveillance camera 11 is, for example, outdoors. The surveillance camera 11 may be installed indoors such as in a factory or a warehouse.

In the surveillance camera 11, the housing portion 17 is supported by the base portion 13 via the angle portion 15. In the first embodiment, the housing portion 17 is, for example, a rectangular parallelepiped. The shape of the housing portion 17 is not limited to this. A sunshade 19 is attached to the upper surface side of the housing portion 17. A translucent cover portion 21 is attached to the front surface of the housing portion 17. The angle portion 15 is pan-rotatable with respect to the base portion 13 in both directions in the direction of arrow a about the center 23 of the pan rotation axis. Further, the housing portion 17 can be tilted and rotated with respect to the base portion 13 in both directions of the arrow b around the tilt shaft 25.

FIG. 2 is an exploded perspective view of the surveillance camera 11 shown in FIG. The housing portion 17 has a front case 27 to which the cover portion 21 is attached and a main body case 29 to which the angle portion 15 is attached.

The rear portion of the camera unit 31 is housed in the main body case 29. The camera unit 31 has a camera body unit 33 and a lens unit 35. The lens unit 35 has a lens 37 on the front end surface. In the lens unit 35, an arc-shaped heater substrate 39 is attached to the front end surface that exposes the lens 37 so as to surround substantially the upper half of the lens 37. A heater (not shown) is mounted on the heater substrate 39. The heater has a first heater 41 and a second heater 43 (see FIG. 14), each of which can be driven independently.

A lens cover 45 is attached to the camera body 33 so as to cover the lens unit 35. The lens cover 45 attached to the camera body 33 is inserted inside the front case 27. A lens exposure opening 47 that exposes the lens 37 is formed on the front end surface of the lens cover 45. An infrared light irradiation device 49 is attached to the front end surface of the lens cover 45 along the outer periphery of the lens 37 exposed to the lens exposure opening 47.

The infrared light irradiation device 49 has an arc-shaped IR (Infrared Ray) -LED (Light Emitting Diode) substrate 51 along the outer periphery of the lens 37, and an IR-LED cover 53 that covers a part of the IR-LED substrate 51. .. A plurality of IR-LEDs 55 (for example, two in the first embodiment) are mounted on the IR-LED substrate 51. The IR-LED cover 53 is formed with an LED window portion that exposes the IR-LED 55. The IR-LED cover 53 is made of a metal having high thermal conductivity (for example, aluminum or copper). The IR-LED cover 53 is fixed to the IR-LED substrate 51 via the heat conductive sheet 57. As a result, the IR-LED substrate 51 can efficiently dissipate heat generated by driving the IR-LED 55 from the IR-LED cover 53 to the surrounding air. The IR-LED cover 53 is arranged so as to face the inner surface of the cover portion 21 attached to the front case 27.

FIG. 3 is a front view of the surveillance camera 11 shown in FIG. The front case 27 is substantially square when viewed from the front. A cover portion 21 is arranged at the center of the front end surface of the front case 27. The cover portion 21 is attached to the opening 59 of the front case 27 so as to be separated from the lens 37. The internal space of the housing portion 17 is opened at the opening portion 59. The cover portion 21 is attached to the opening portion 59 to seal the housing portion 17. Since the cover portion 21 has translucency, the cover portion 21 transmits the object light from the subject and causes the object light to be incident on the lens 37. The opening 59 is arranged so as to face the light incident surface of the lens 37.

For the cover portion 21, a resin material having excellent moldability and transparency can be used as the substrate material. Resin materials include organic resin materials and inorganic resin materials. In the first embodiment, an organic resin material such as polycarbonate is used as the substrate material of the cover portion 21. Polycarbonate is suitable because it is hard and resistant to impact. Further, a resin having good transparency such as acrylic can be used for the cover portion 21.

FIG. 4 is a sectional view taken along the line AA of FIG. The housing portion 17 covers the camera portion 31. The housing portion 17 has an opening 59 corresponding to the lens 37 to support the camera portion 31 and surround the camera portion 31 with a gap 61. The camera unit 31 is provided with a fan 63 as an example of the blower device. In the first embodiment, the fan 63 is an axial fan in which the fan blades are rotated by a motor (not shown). The fan 63 is arranged in the gap 61 and circulates the air in the gap 61 with the cover portion 21. The structure of the fan 63 is not limited to this, and may be a sirocco fan or the like that blows air in a direction orthogonal to the rotation axis.

FIG. 5 is a cross-sectional view taken along the line BB of FIG. A vent 65 is formed in the housing portion 17. The vent 65 opens the gap 61 to the outside 67. In the first embodiment, the vent 65 is arranged on the lower surface side of the main body case 29 constituting the housing portion 17. The vent 65 is arranged on the blowout side of the fan 63.

FIG. 6 is a perspective view showing the mounting structure of the waterproof ventilation film 69 in the surveillance camera 11 of FIG. 1 together with an enlarged view of a main part. The vent 65 is closed by the waterproof vent film 69. The waterproof ventilation film 69 does not allow water to pass through, but allows air to pass through. The air passed through the waterproof ventilation film 69 contains water vapor. That is, the waterproof ventilation film 69 allows the passage of water molecules. The waterproof ventilation film 69 is attached to the ventilation port 65, and then attached by a protective sheet 70 having a circular center opening. The opening diameter of the protective sheet 70 matches or substantially matches the diameter of the vent 65. The vent 65 is formed, for example, in a circular shape. The vent 65 opens at the bottom of the membrane mounting recess 71 recessed in the outer surface of the housing 17. The waterproof ventilation film 69 is arranged with the same or substantially the same diameter as the ventilation port 65 opened at the bottom of the membrane mounting recess 71, and the waterproof ventilation film 69 is further attached by attaching a protective sheet 70 having an opening in the center. Peeling is prevented. The waterproof breathable membrane 69 arranged in the membrane mounting recess 71 is protected by the cover plate 73 mounted in the membrane mounting recess 71. A ventilation slit 75 is formed in the cover plate 73.

FIG. 7 is an enlarged view of a main part of FIG. 4 showing a flow path of air containing water vapor. When the fan 63 is driven, the surveillance camera 11 circulates the air in the gap 61 between the fan 63 and the cover portion 21 in the direction indicated by the arrow in FIG. 7. The air blown out from the fan 63 flows toward the cover portion 21 through the gap 61 as a flow path, flows along the inner surface of the cover portion 21, and then returns to the suction side of the fan 63 through the other gap 61. .. Here, the flow path does not have to be the one shown in FIG. 7. However, it is preferable that the air is blown out from the fan 63, comes into contact with the inner surface of the cover portion 21, and then returns to the fan 63 as reflux. That is, the inner surface of the cover portion 21 is designed so that an air stagnation region isolated from the air flow (so-called circulation 77) does not occur. Even if the mainstream of Circulation 77 does not flow on the inner surface of the cover portion 21, its tributary 79 may flow.

(Embodiment 2)
Next, the surveillance camera 81 according to the second embodiment will be described with reference to FIGS. 8 to 13.

FIG. 8 is a perspective view showing an example of the surveillance camera 81 according to the second embodiment. In the second embodiment, the same members and the same parts as the members shown in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

The surveillance camera 81 according to the second embodiment is a surveillance camera having a so-called dome-shaped housing. The installation environment of the surveillance camera 81 is, for example, outdoors. The surveillance camera 81 may be installed indoors such as in a factory or a warehouse.

The surveillance camera 81 has a housing portion 17 and a cover portion 21.

In the second embodiment, the housing portion 17 includes a dome case 83, a main body case 85 (see FIG. 11), and an inner case 87 (see FIG. 11). The dome case 83 is attached to the main body case 85 by a plurality of fixing screws 89. The inner case 87 is fixed to the main body case 85 by a fixing screw (not shown). A camera unit 31 (see FIG. 9) is supported by the inner case 87.

The surveillance camera 81 is attached to, for example, a ceiling, a wall, a support pole for a surveillance camera, or the like via a mounting bracket (not shown). The camera unit 31 is fixed to the inner case 87 so as to be oriented in a desired direction in the pan rotation direction centered on the pan rotation center. The pan rotation direction is, for example, the rotation direction around the pan rotation center axis perpendicular to the ceiling surface or the wall surface to which the surveillance camera 81 is attached. Further, the tilt rotation direction described later is a rotation direction around the tilt axis in a direction perpendicular to the pan rotation center axis.

In the second embodiment, the cover portion 21 is formed in a dome shape in which a cylindrical straight portion 93 is continuous on the opening edge of the hemispherical portion 91. The dome case 83 is formed in an annular shape into which the hemispherical portion 91 of the cover portion 21 is inserted inward. As the material of the cover portion 21, the same material as that of the first embodiment can be used.

FIG. 9 is an exploded perspective view of the surveillance camera 81 shown in FIG. The camera unit 31 has an annular plate-shaped pan angle 95 rotatably supported in the pan rotation direction in the inner case 87. A pair of tilt arms 97 are formed upright on the pan angle 95. The pan angle 95 rotatably supports a tilt angle 101 formed in a ring plate shape having a diameter smaller than that of the pan angle 95 on the pair of tilt arms 97 via a tilt fixing screw 99. The lens unit 103 is fixed to the tilt angle 101.

A lens 37 is provided on the front end surface of the lens unit 103. An arcuate heater substrate 39 is attached to the front end surface of the lens unit 103 along the outer circumference of the lens 37. A heater is mounted on the heater substrate 39. The heater has a first heater 41 and a second heater 43 (see FIG. 14), each of which can be independently driven, as in the first embodiment. A lens cover 105 is attached to the lens unit 103 so as to cover the heater substrate 39. A ring-shaped light-shielding rubber 107 is attached to the front end surface of the lens cover 105. The light-shielding rubber 107 is in close contact with the inner surface of the cover portion 21 (see FIG. 11).

An infrared light irradiation device 49 is attached to the tilt angle 101. The infrared light irradiation device 49 has a pair of IR-LED substrates 109 formed in an arc shape and a pair of IR-LED covers 111 attached to the respective IR-LED substrates 109. The IR-LED substrate 109 is arranged so as to sandwich the center of the tilt angle 101 formed in an annular shape. The IR-LED cover 111 is attached by exposing the IR-LED 55 provided on the IR-LED substrate 109 and covering the IR-LED substrate 109. The side surface of the lens unit 103 is covered with a pair of side surface covers 114. A bottom cover 115 is attached to the rear end surface of the lens unit 103 opposite to the lens 37 via an annular wave washer 113, so that the lens unit 103 can rotate in the yaw rotation direction.

FIG. 10 is a front view of the surveillance camera 81 shown in FIG. In the surveillance camera 81 accommodating the lens unit 103, the circular dome case 83 and the cover portion 21 are arranged concentrically in a plan view. The cover portion 21 is attached to the opening portion 59 that opens at the central portion of the dome case 83. The cover portion 21 attached to the opening portion 59 seals the housing portion 17 with the dome case 83 and the main body case 85. The cover portion 21 formed in a hemispherical dome shape has a radius substantially half of the radius of the surveillance camera 81 and rises at the central portion of the housing portion 17 to cover the camera portion 31.

11 is a cross-sectional view taken along the line CC of FIG. In the housing portion 17, the inner case 87 supports the camera portion 31, and the dome case 83 surrounds the camera portion 31 with a gap 61. The housing portion 17 is provided with a vent 65 in the inner case 87. The vent 65 opens the gap 61 to the outside 67. In the present embodiment, the vent 65 is arranged on the side surface side of the main body case 85 constituting the housing portion 17. The vent 65 that opens on the side surface side of the main body case 85 is covered with a dome case 83 arranged with a gap 117. The vent 65 leads to the outside 67 through the gap 117.

The ventilation port 65 of the inner case 87 is closed by the same waterproof ventilation film 69 as described above.

FIG. 12 is a cross-sectional view taken along the line DD of FIG. The inner case 87 is provided with a fan 63 as a blower. In the present embodiment, the fan 63 is an axial fan in which the fan blades are rotated by a motor. The fan 63 is arranged in the gap 61 and circulates the air in the gap 61 with the cover portion 21.

FIG. 13 is a perspective view showing a flow path of air with a part of FIG. 8 cut out. In the surveillance camera 81, when the fan 63 is driven, the air in the gap 61 circulates between the fan 63 and the cover portion 21 in the direction indicated by the arrow in FIG. The air blown out from the fan 63 flows toward the cover portion 21 through the gap 61 as a flow path, flows along the inner surface of the cover portion 21, and then returns to the suction side of the fan 63 through the other gap 61. .. Here, the flow path does not have to be particularly specified. However, it is a requirement that the air is blown out from the fan 63, comes into contact with the inner surface of the cover portion 21, and then returns to the fan 63 as reflux. That is, the inner surface of the cover portion 21 is designed so that an air stagnation region isolated from the air flow (so-called circulation) does not occur. Even if the mainstream of Circulation 77 does not flow on the inner surface of the cover portion 21, its tributary 79 may flow.

Next, the main internal configurations of the surveillance cameras 11 and 81 according to the first and second embodiments will be described with reference to FIG.

FIG. 14 is a block diagram showing an example of the main internal configurations of the surveillance cameras 11 and 81 according to the first and second embodiments. The surveillance cameras 11 and 81 mainly include a camera unit 31, a housing unit 17, a cover unit 21, a fan 63, a vent 65, a waterproof ventilation film 69, a heater, and an IR-LED55, respectively. It has as a basic configuration.

Further, the surveillance camera 11 and the surveillance camera 81 have a temperature sensor 119 for detecting the temperature of air and a control unit 121 as a main configuration. The control unit 121 individually controls the operation and stop of the fan 63 and the heater based on the temperature detection signal from the temperature sensor 119 and the current value of the IR-LED55.

In the surveillance cameras 11 and 81, as described above, the heater has a first heater 41 and a second heater 43 having a smaller calorific value than the first heater 41. The control unit 121 individually controls the operation and stop of the first heater 41 and the second heater 43.

In the surveillance cameras 11 and 81, the first heater 41 and the second heater 43 are arranged on the downstream side of the IR-LED 55 in the flow path of the air flowing from the fan 63 to the cover portion 21.

Further, the surveillance camera 11 and the surveillance camera 81 are provided with a PoE (Power of Ethernet (registered trademark)) power supply 123. The PoE power supply 123 is supplied with power supply 125 via a LAN (Local Area Network) cable or the like connected to the surveillance cameras 11 and 81. The power supply 125 may be, for example, DC (Direct Current) 12V in addition to PoE.

Next, a method for suppressing dew condensation common to the configurations of the surveillance cameras 11 and 81 according to the first and second embodiments will be described with reference to FIGS. 15 and 16.

FIG. 15 is a flowchart showing an example of the operation procedure of the dew condensation suppressing method in the surveillance cameras 11 and 81 according to the first and second embodiments. FIG. 16 is a diagram showing an example of a heater control table. The heater control table is stored in a memory (see below) among the processor (not shown) and the memory (not shown) constituting the control unit 121, for example.

The processor is configured by using, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor) or an FPGA (Field Programmable Gate Array). The processor functions as a part of the control unit 121 of the surveillance cameras 11 and 81, and controls processing for overall control of the operation of each unit of the surveillance cameras 11 and 81, and between each unit of the surveillance cameras 11 and 81. Performs data or information input / output processing, data calculation processing, and data or information storage processing. The processor operates according to the programs and data stored in the memory.

The memory is configured by using, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory), and is a program or data necessary for executing the operation of the monitoring cameras 11 and 81, and information or information generated during the operation. Temporarily save data etc. The RAM is, for example, a working memory used when the control unit 121 is operated. The ROM stores, for example, a program and data for controlling the control unit 121 in advance. Further, the ROM may hold the heater control table (see FIG. 16) described above.

In the dew condensation suppression method in the surveillance cameras 11 and 81, specific control is executed by, for example, the surveillance cameras 11 and 81 having the configuration shown in FIG.

As a method for suppressing dew condensation on a surveillance camera, for example, when the power supply 125 is turned on, the normal mode is activated (St1). The control unit 121 stops the operation of the heater and the fan 63 in the normal mode. The temperature range in normal mode can be, for example, 10 ° C to 60 ° C and may be pre-stored in memory (see above).

In the normal mode, the control unit 121 receives a temperature detection signal from the temperature sensor 119 (that is, a signal including the temperature detection value measured by the temperature sensor 119) at predetermined time intervals. That is, the control unit 121 constantly monitors the temperature status of the air around the gap 61. Generally, the control unit 121 operates the heater and the fan 63 when the detected temperature value of the temperature sensor 119 is lower than the predetermined temperature value, and further, when the detected temperature of the temperature sensor 119 starts to decrease in temperature. The heater and fan 63 are stopped when the temperature rises above the temperature.

More specifically, the control unit 121 determines that the temperature value by the temperature detection signal is equal to or less than the predetermined temperature value and the amount of change in the temperature value is equal to or less than the predetermined value (St2), and the dew condensation prevention mode (St2). That is, the operation mode for suppressing dew condensation on the surveillance cameras 11 and 81) is controlled (St3). Here, the predetermined temperature value can be any temperature value in the range of, for example, 30 ° C. to 40 ° C., and may be stored in a memory (see above) in advance. Further, the change amount of the temperature value is a falling temperature value within a predetermined time. The predetermined time can be, for example, 60 min (ie, 60 minutes) and may be pre-stored in memory (see above). The falling temperature value can be any temperature in the range of, for example, −5 ° C. to −15 ° C., and may be stored in advance in a memory (see above).

Therefore, the control unit 121 activates the dew condensation prevention mode when the temperature value according to the temperature detection signal drops from, for example, 35 ° C. to 7 ° C. in 1 minute. As a result, the surveillance cameras 11 and 81 can suppress dew condensation in response to sudden changes in the weather due to the surrounding outdoor environment, for example, when a downburst occurs or a squall occurs, and the visibility of the captured image deteriorates. Can be suppressed.

The control unit 121 operates the heater and the fan 63 in the dew condensation prevention mode. Here, the control unit 121 individually controls the operation of the first heater 41 and the second heater 43 when the IR-LED 55 is operating. The control unit 121 performs individual control of the first heater 41 and the second heater 43 according to the heater control table according to the current value of the IR-LED 55. An example of the heater control table is shown in FIG. In FIG. 16, the unit of electric current of the IR-LED55 is "mA" (milliampere). Further, the unit of the electric power (that is, the power consumption by the current of the IR-LED55), the output power of the 1.5W heater, the output power of the 1.2W heater, and the total value is "mW" (milliwatt).

Surveillance cameras 11 and 81 are supplied with electric power by PoE technology via a LAN cable or the like. Therefore, the control unit 121 takes into consideration the limitation of the electric power that can be supplied by the PoE power supply 123 so that the total electric power of the first heater 41, the second heater 43, and the IR-LED55 is about 3000 to 3500 mW or less. , The control is performed by combining the operations of the first heater 41 and the second heater 43.

As described above, the heater has a first heater 41 and a second heater 43 having a smaller calorific value than the first heater 41. As an example, the first heater 41 may be, for example, 1.5 W, and the second heater 43 may be, for example, 1.2 W. The control unit 121 controls the operation and stop of the first heater 41 and the second heater 43 individually in combination according to the current value of the infrared light irradiation device 49.

As shown in the heater control table shown in FIG. 16, the control unit 121 stops the first heater 41 and the second heater 43, for example, when the current of the IR-LED55 is 352 mA or more. The control unit 121 operates the second heater 43 when the current of the IR-LED 55 drops to 336 mA. When the current of the IR-LED 55 drops to 252 mA, the control unit 121 stops the second heater 43 and operates the first heater 41. When the current of the IR-LED 55 is further reduced to 110 mA, the control unit 121 operates both the first heater 41 and the second heater 43. The surveillance camera 11 and the surveillance camera 81 can suppress the total power to about 3000 mW or less by this combination control by the control unit 121.

In FIG. 16, the down arrow indicates the decreasing direction of the current change in the infrared light irradiation device 49, and the up arrow indicates the increasing direction of the current change in the infrared light irradiation device 49.

The control unit 121 monitors the temperature detection signal by the temperature sensor 119 in the dew condensation prevention mode. The control unit 121 determines whether or not the temperature of the temperature detection signal is equal to or higher than the temperature at the start of the temperature decrease and 30 minutes or longer has elapsed (St4). The temperature at the start of the temperature drop is 35 ° C. in the above example. Therefore, when the temperature reaches 35 ° C. for 30 minutes, the control unit 121 stops the heater and the fan 63 (St5), and returns to the control of the normal mode.

Here, the reason for counting the delay of 30 min is to prevent the heater and the fan 63 from being repeatedly operated and stopped in a short time (so-called short cycle). The above is the procedure of the dew condensation suppression method of the surveillance camera.

Next, the operation of the configuration according to the surveillance cameras 11 and 81 according to the first and second embodiments will be described.

The surveillance cameras 11 and 81 according to the first and second embodiments support the camera unit 31 having a camera unit 31 having a lens 37 and an opening 59 substantially matching the lens 37, and the cameras are separated by a gap 61. The housing portion 17 surrounding the portion 31, the translucent cover portion 21 attached to the opening 59 separated from the lens 37 and sealing the housing portion 17, and the air in the gap 61 arranged in the gap 61. In the gap 61, the fan 63 that circulates the light between the cover portion 21, the vent 65 that is bored in the housing portion 17 and opens the gap 61 to the outside 67, the waterproof ventilation film 69 that closes the vent 65, and the gap 61. It is provided with a heater provided facing the lens to heat the air, and an infrared light irradiating device 49 provided facing the gap 61 to emit infrared light to the outside 67 through the cover portion 21 and dissipate the light to the air. ..

In the surveillance cameras 11 and 81 according to the first and second embodiments, when the fan 63 is driven, the air in the gap 61 circulates between the fan 63 and the cover portion 21. The air blown out from the fan 63 flows toward the cover portion 21 through the gap 61 as a flow path, flows along the inner surface of the cover portion 21, and then returns to the suction side of the fan 63 through the other gap 61. .. Here, the flow path does not have to be particularly specified. However, it is a requirement that the air is blown out from the fan 63, comes into contact with the inner surface of the cover portion 21, and then returns to the fan 63 as reflux. That is, the inner surface of the cover portion 21 is designed so that an air stagnation region isolated from the air flow (so-called circulation) does not occur.

A vent 65 is formed on the inner wall surface of the housing portion 17 constituting the gap 61. The vent 65 is passed through the inside and outside of the housing. The vent 65 is covered with a waterproof vent film 69. The waterproof ventilation film 69 allows air (including water vapor) to pass inside and outside the housing, while blocking the passage of liquid. Therefore, the water vapor in the housing is exhausted to the outside 67 through the waterproof ventilation film 69, so that the water in the housing is discharged to the outside 67.

A heater and an infrared light irradiation device 49 are provided in the gap 61 in contact with the air in the gap 61. The heater heats the air in the gap 61. The infrared light irradiation device 49 dissipates heat generated by the operation to the air in the gap 61. That is, both the heater and the infrared light irradiation device 49 raise the air temperature in the gap 61.

Here, in the surveillance camera 11 and the surveillance camera 81 sealed by the housing portion 17 and the cover portion 21, when the temperature of the external air decreases, the temperatures of the housing portion 17 and the cover portion 21 decrease due to heat transfer. The inner surface of the cover portion 21 is lowered by heat conduction from the outer surface. Therefore, a temperature difference occurs between the inner surface of the cover portion 21 and the air in the gap 61. At this time, for example, it is assumed that the temperature of the external 67 is 20 ° C. and the relative humidity is 50%. The absolute humidity at this time is 0.0073 kg / kg from the psychrometric chart. Further, it is assumed that the sealed surveillance camera 11 and the surveillance camera 81 have an air temperature of 40 ° C. and a relative humidity of 50% in the gap 61. The absolute humidity at this time is 0.0236 kg / kg from the psychrometric chart. The dew point temperature of the inner surface of the cover portion 21 is 27.5 ° C.

The air at 40 ° C. in the gap 61 is gradually reduced by being dissipated from the cover portion 21 and the housing portion 17 to the outside 67. If the inner surface of the cover portion 21 drops to 27.5 ° C., the water vapor contained in the air in the gap 61 condenses into a liquid on the inner surface of the cover portion 21 and causes dew condensation. The dew condensation diffusely reflects the incident light from the cover portion 21 and deteriorates the captured image.

Therefore, in the surveillance cameras 11 and 81 according to the first and second embodiments, when the air temperature of 40 ° C. drops to a predetermined temperature (for example, 35 ° C.), the fan 63 and the heater are operated. Here, the temperature of 40 ° C. is the start temperature of the temperature decrease. The air in the gap 61 rises from 35 ° C. due to the heat generated by the heater or the like. As a result of the temperature rise, the air in the gap 61 again reaches the starting temperature of 40 ° C. for the temperature drop. In the surveillance cameras 11 and 81, when the temperature of the air in the gap 61 rises to the starting temperature of 40 ° C., the fan 63 and the heater are stopped. In reality, the air in the gap 61 becomes 40 ° C. or higher due to control by a delay timer or the like or a delay in heat transfer conduction.

At this time, the heated air blown by the fan 63 flows along the inner surface of the cover portion 21. That is, heat from the air is transferred to the inner surface of the cover portion 21 by heat transfer. As a result, dew condensation is suppressed on the inner surface of the cover portion 21 without lowering the dew point temperature to 27.5 ° C.

Further, a waterproof ventilation film 69 is arranged in the flow path through which air circulates between the fan 63 and the cover portion 21. The air in the gap 61 heated to 35 ° C. or higher passes through the waterproof ventilation membrane 69 together with water vapor and is gradually exhausted to the outside 67. Of the flow paths through which air circulates, the flow path through which the air blown out from the fan 63 flows toward the cover portion 21 is on the positive pressure side due to the air transfer energy of the fan 63. On the other hand, the flow path on the reflux side from the cover portion 21 to the fan 63 is on the negative pressure side. The waterproof ventilation film 69 can be provided on this positive pressure side. By providing the waterproof ventilation film 69 on the positive pressure side, water vapor can be effectively exhausted to the outside 67 as compared with the case where the waterproof ventilation film 69 is provided on the negative pressure side.

The surveillance camera 11 and the surveillance camera 81 can be provided with a vent 65 and a waterproof vent film 69 that closes the vent 65 at two locations. In this case, the two vents 65 and the waterproof vent film 69 are arranged with one on the positive pressure side of the gap 61 and the other on the negative pressure side. According to the surveillance camera 11 and the surveillance camera 81 having such a configuration, the air having a high absolute humidity is discharged to the outside 67 from the waterproof ventilation film 69 on the positive pressure side, and at the same time, the outside air having a low absolute humidity is taken into the gap 61. be able to. As a result, the inside of the housing can be dehumidified in a shorter time.

When a certain amount of pressure drop occurs in the housing due to the exhaust gas, the outside air flows into the gap 61 through the waterproof ventilation membrane 69. At this time, the absolute humidity of the air exhausted to the outside 67 is 0.0236 kg / kg as described above, and the absolute humidity of the outside air flowing into the gap 61 from the outside 67 is 0.0073 kg / kg as described above. It is kg. Therefore, roughly (0.0236-0.0073) = 0.0163 kg / kg of dehumidification is performed.

If all the air in the gap 61 and the air in the outside 67 are exchanged, the air in the gap 61 in the housing has an absolute humidity of 0.0073 kg / kg at 40 ° C. The relative humidity at this time is 16% from the psychrometric chart. The dew point temperature is 9 ° C. That is, the air in the gap 61 is dehumidified (dried) to a water content that does not cause dew condensation unless the inner surface of the cover portion 21 drops to 9 ° C. As a result, it is possible to reduce the driving time of the heater for suppressing dew condensation.

In this way, in the surveillance cameras 11 and 81, dehumidification is performed every time the dehumidification mode is activated. The surveillance cameras 11 and 81 can suppress dew condensation on the cover portion 21 by a synergistic effect of dew condensation suppression by warming the inner surface of the cover portion 21 and dehumidification of the internal air. As a result, deterioration of image quality due to dew condensation can be more effectively suppressed while suppressing an increase in running cost.

Further, in a conventional surveillance camera, an expensive dehumidifying element may be mounted for dehumidifying. On the other hand, since the surveillance cameras 11 and 81 can dehumidify without using the dehumidifying element, the manufacturing cost and the running cost can be reduced as compared with the case where the dehumidifying element is mounted.

Therefore, according to the surveillance camera 11, the surveillance camera 81, and the method for suppressing dew condensation of the surveillance camera according to the present embodiment, the increase in manufacturing cost and running cost is suppressed, and dew condensation and icing are prevented while effectively utilizing the internal heat generation. It can be suppressed.

Further, the monitoring cameras 11 and 81 operate the fan 63 and the heater based on the temperature sensor 119 that detects the temperature of the air, the temperature detection signal from the temperature sensor 119, and the current value of the infrared light irradiation device 49. A control unit 121 for individually controlling the stop is provided.

In this way, in the surveillance cameras 11 and 81, the temperature of the air circulating in the gap 61 is detected by the temperature sensor 119. The temperature detection signal from the temperature sensor 119 is input to the control unit 121. Further, the control unit 121 acquires the current value of the infrared light irradiation device 49. The control unit 121 can independently control the operation and stop of the fan 63 and the operation and stop of the heater based on the temperature detection signal and the current value of the infrared light irradiation device 49.

Further, in the surveillance cameras 11 and 81, the heater has a first heater 41 and a second heater 43 having a smaller calorific value than the first heater 41.

In this way, in the surveillance cameras 11 and 81, the control unit 121 can individually drive and control the heater and the second heater 43 having a smaller heat generation amount than the first heater 41. The control unit 121 is finely divided by combining the drive of only the first heater 41, the drive of only the second heater 43, and the drive of the first heater 41 and the second heater 43 according to the current value of the infrared light irradiation device 49. Control is possible. This makes it possible to further reduce unnecessary current consumption.

Further, in the surveillance cameras 11 and 81, the heater is arranged on the downstream side of the infrared light irradiation device 49 in the flow path of the air flowing from the fan 63 to the cover portion 21.

As described above, in the surveillance cameras 11 and 81, the heat generated by the heater can be directly and efficiently supplied to the cover portion 21. As a result, dew condensation can be efficiently suppressed. Further, it is not necessary to directly raise the temperature of the infrared light irradiation device 49 by the heat of the heater.

Further, the installation environment of the surveillance cameras 11 and 81 is outdoors.

As described above, in the surveillance cameras 11 and 81, dew condensation can be less likely to occur than in the conventional structure due to both the dew condensation suppressing effect of the cover portion 21 due to the temperature rise and the dew condensation suppressing effect of the cover portion 21 due to the dehumidification. As a result, it is possible to sufficiently suppress dew condensation on the cover portion 21 and continue to acquire a captured image with high sharpness, particularly even outdoors where a sudden temperature change is likely to occur due to weather conditions.

Further, in the method for suppressing dew condensation of the surveillance cameras 11 and 81 according to the first and second embodiments, the camera unit 31 having the lens 37 and the opening 59 corresponding to the lens 37 are provided to support the camera unit 31 and the gap 61 is supported. A housing portion 17 that surrounds the camera portion 31, a translucent cover portion 21 that is attached to the opening 59 apart from the lens 37 and seals the housing portion 17, and a translucent cover portion 21 that is arranged in the gap 61. A fan 63 that circulates the air in the gap 61 between the cover portion 21 and a vent 65 that is formed in the housing portion 17 to open the gap 61 to the outside 67, and a waterproof vent film 69 that closes the vent 65. A heater provided facing the gap 61 to heat air, an infrared light irradiating device 49 provided facing the gap 61 to emit infrared light to the outside 67 through a cover portion 21 and dissipate heat to the air, and air. A temperature sensor 119 for detecting the temperature of the lens 119 and a control unit 121 for individually controlling the operation and stop of the fan 63 and the heater based on the temperature detection signal from the temperature sensor 119 and the current value of the infrared light irradiation device 49. A method for suppressing dew condensation on the monitoring camera 11, the control unit 121 operates the heater and the fan 63 when the detection temperature of the temperature sensor 119 is lower than a predetermined temperature, and the detection temperature of the temperature sensor 119 starts to decrease. The heater and fan 63 are stopped when the temperature is higher than the current temperature.

As described above, in the dew condensation suppressing method of the surveillance cameras 11 and 81 according to the first and second embodiments, the temperature detection signal from the temperature sensor 119 is input to the control unit 121. The control unit 121 acquires the current value of the infrared light irradiation device 49. The control unit 121 controls the operation and stop of the fan 63 and the heater based on these temperature detection signals and the current value of the infrared light irradiation device 49. For example, when the temperature detection signal of the temperature at which the dew condensation prevention mode is started is input, the control unit 121 refers to the current value of the infrared light irradiation device 49. When the current value of the infrared light irradiation device 49 is large, only the fan 63 is driven and the heater is left stopped. That is, the heat generated by the infrared light irradiation device 49 is used. On the other hand, when the temperature detection signal of the temperature at which the dew condensation prevention mode is started is input, if the current value of the infrared light irradiation device 49 is small, the fan 63 and the heater are driven. As a result, when the amount of heat for heating the air can be covered by the exhaust heat of the infrared light irradiation device 49, the wasteful current consumption of the heater can be reduced.

Further, in the method for suppressing dew condensation of the surveillance cameras 11 and 81, the heater has a first heater 41 and a second heater 43 having a calorific value smaller than that of the first heater 41, and the control unit 121 has an infrared light. The operation and stop of the first heater 41 and the second heater 43 are individually combined and controlled according to the current value of the irradiation device 49.

As described above, in this method of suppressing dew condensation on the surveillance camera, the control unit 121 individually drives and controls the heater and the second heater 43, which generates less heat than the first heater 41. The control unit 121 is finely controlled by combining the drive of only the first heater 41, the drive of only the second heater 43, and the drive of the first heater 41 and the second heater 43 according to the current value of the infrared light irradiation device 49. Is possible. This makes it possible to further reduce unnecessary current consumption.

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present disclosure is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications, modifications, substitutions, additions, deletions, and even examples within the scope of the claims. It is naturally understood that it belongs to the technical scope of the present disclosure. Further, each component in the various embodiments described above may be arbitrarily combined as long as the gist of the invention is not deviated.

The present disclosure is useful as a surveillance camera and a method for suppressing dew condensation of a surveillance camera that can suppress an increase in manufacturing cost and running cost, and can suppress dew condensation and icing while effectively utilizing internal heat generation.

11 Surveillance camera 17 Housing 21 Cover 31 Camera 37 Lens 41 1st heater 43 2nd heater 49 Infrared light irradiation device 59 Opening 61 Gap 63 Fan 65 Vent 67 External 69 Waterproof vent film 119 Temperature sensor 121 Control Department

Claims (5)

The camera part with the lens and
A housing portion having an opening facing the light incident surface of the lens to support the camera portion and surrounding the camera portion with a gap.
A translucent cover portion that is attached to the opening portion apart from the lens and seals the housing portion.
A fan arranged in the gap and circulating air in the gap between the cover portion and the fan.
A vent that is bored in the housing and opens the gap to the outside,
With a waterproof ventilation membrane that closes the ventilation holes ,
The waterproof ventilation film is arranged in a flow path through which the air blown from the fan flows toward the cover portion.
Surveillance camera. A plurality of the vents and the waterproof ventilation membrane are provided.
The surveillance camera according to claim 1. One of the vent and the waterproof vent film is arranged in a flow path through which the air blown from the fan flows toward the cover portion, and one of the vent and the waterproof vent film is the cover portion. Arranged in the flow path on the return side from the fan to the fan,
The surveillance camera according to claim 2 . A heater, which is provided facing the gap and heats the air, is further provided.
The surveillance camera according to any one of claims 1 to 3. The heater has a first heater and a second heater having a smaller calorific value than the first heater.
The surveillance camera according to claim 4 .

Images