WO2008033008A2

WO2008033008A2 - Video surveillance camera housing

Info

Publication number: WO2008033008A2
Application number: PCT/NL2007/000201
Authority: WO
Inventors: Johannes Petrus Marinus Cornelis Van Schijndel
Original assignee: Internova Holding Bvba
Priority date: 2006-08-17
Filing date: 2007-08-16
Publication date: 2008-03-20
Also published as: EP2055094A2; NL1032335C1; WO2008033008A3

Abstract

A camera (1) is described, comprising a camera housing (100), which is provided with shield plates (210, 220) mounted along the side walls (130, 140) and a channel (123) arranged against the upper wall (120) at the outside for a forced air flow (AFl) for controlling the temperature. In the front wall (110), a viewing opening (111) with a viewing glass (112) is located, provided at the outer side with a water-repellent coating of titanium oxide. At the front side of the camera housing, the air flow is bent and guided along the viewing glass. The interior (170) of the camera housing is subdivided into two thermal zones (171, 172), wherein the image pick-up chip is arranged in the rear zone while the front zone is provided with heating means for heating the viewing glass and the entrance lens of the lens system.

Description

Title: Camera housing

The present invention relates in general to a camera housing for a camera, suitable for placement outdoors and use as surveillance camera.

Surveillance cameras are generally known. Such cameras can for instance be used for monitoring unmanned facilities from a distance, such as bridges, gas stations, or for instance traffic flows, et cetera. The images provided by the camera will typically be watched continuously by remote surveillance personnel, in order to be able to take action immediately if necessary. Such cameras can also be used for recording events, in which case the camera images can be. played back later, for instance in order to be able to recognize the perpetrator of a punishable act. Although there are several types of surveillance camera, a surveillance camera typically has an elongated, box shaped housing with a viewing window arranged at one end, with behind it, in the housing, a lens, an image pick-up, an a signal processing circuit for processing and transmitting the images provided by the image pick-up.

When a camera is intended for use outdoors, different requirements are set to the camera as compared to use indoors. The most important aspects in this context are humidity and temperature. On its outside, the viewing window can become dirty by rain and other deposit, and on its inside it can become dirty by condensation, causing the image quality to be reduced or it may even become entirely impossible to pick-up images. Further, temperature variations may affect the operation of the- image pick-up chip. It is an important objective of the present invention to provide a high quality camera in which a good image quality can be assured drastically under various atmospheric conditions.

Particularly, the present invention aims to provide a camera in which the influence of weather influences on the image quality is eliminated or at least drastically counter acted.

These and other aspects, features and advantages of the present invention will further be elucidated by the following description with reference to the drawings, in which same reference numerals indicate same or similar parts, and in which: figure 1 shows a perspective front view of a camera according to the present invention; figure 2 shows a perspective top view of the housing of the camera in open condition; figure 3 shows a schematical cross section of the camera housing; figure 4 shows a schematical longitudinal section of the camera housing; figure 5 at a larger scale shows a schematic longitudinal section of the front part of the camera housing; and figure 6 shows a schematic top view of the camera housing.

Figure 1 shows a perspective front view of a camera 1 according to the present invention. The camera 1 comprises a housing 100 in the shape of an elongated box, of which figure 2 shows a perspective top view, in open condition. The figures 3 and 4 schematically show a cross section and a longitudinal section, respectively, of the housing 100. The camera housing 100 comprises a front wall 110, a top wall 120, side walls 130, 140, a rear wall 150, and a bottom 160. The interior of the housing is indicated by the reference numeral 170. A viewing opening 111 is located in the front wall 110, with a viewing glass 112 in it. The viewing glass 112 is made of a material which is transmissive for light, particularly visible light and preferably also infra red light. For instance, the viewing glass 112 is made of glass, crystal, or the like.

The optical and electronic components of the camera 1 are arranged in the interior of the housing 100. These components comprise: an optical detector, also indicated as image chip, for instance implemented as CCD chip; a lens system, for focusing onto the image chip light which enters the housing 100 through the viewing opening 111; and a signal processing processor for processing signals generated by the image chip. Since the components mentioned are components known per se, while the present invention is not aimed at improving said components and may be implemented with components known per se, these components are not shown in the figures 1-4 for sake of simplicity and their operation will not be described in more detail. The same applies for components for storing or outputting the image signals, and components for providing electrical supply. The camera 1 may be provided with a hard disc or any other suitable storage medium. The camera may be provided with a connection cable for receiving electrical supply and for delivering an electrical signal for further processing, display and/or storage of the image signals.

An important aspect of the camera 1 is the control of the temperature in the housing. According to an important aspect of the present invention, the housing 100 is provided with an ingenious external temperature shield 200, illustrated in the perspective view of figure 1 and the cross section of figure 3. The temperature shield 200 comprises a first shield plate 210, associated with the one side wall 130, and a second shield plate 220, associated with the other side wall 140. Since the two shield plates may be implemented symmetrically and may be arranged symmetrically, in the following only the first shield plate 210 will be described in more detail. The shield plate 210 is a plate-shaped body connected to the first side wall 130 of the housing 100, for instance by means of screws, the shield plate 210 being kept at a -short distance from the side wall 130 by distance holders 212. Length and height of the shield plate 210 correspond with those of the side wall 130; advantages are offered if the length of the shield plate 210 is somewhat larger then the length of the side wall 130. In the preferred embodiment shown, the distance holders 212 are implemented as two vertically extending ribs which extend over the entire height of the side wall 130, and which at each height bridge the complete distance between the shield plate 210 and the side wall 130. The ribs 212 are positioned close to the front side and close to the rear side of the side wall 130, respectively, such that the mutual distance between the two ribs 212 is as large as possible. It is possible that more of such ribs are arranged, distributed over the length of the sidewall 130, but this is not necessary and is not preferred.

A first function of the shield plate 210 is to counter act a direct irradiation of solar radiation onto the side wall 130.

A second function of the shield plate 210 is defining a thermally insulating space 215 between the shield plate 210 and the side wall 130.

The shield plate 210 has a lower edge 213 and an upper edge 214. The distance between the lower edge 213 and the side wall

130 is indicated by dl in figure 3, and the distance between the upper edge 214 and the side wall 130 is indicated by d2 in figure 3. It is clearly shown that dl is larger than d2. Further, it is shown that the shield plate 210 is implemented in a concave manner in a preferred embodiment, while the side wall 130 is substantially flat and is vertically directed, such that the mutual distance between the shield plate 210 and the side wall 130 has a maximum that is achieved at approximately half the height. The said space 215 thus has at its lower end a gap 216 that is wider than the gap 217 at its upper end. For this reason, a vertical air flow is possible in the space 215, as indicated by an arrow 218,- which air flow is accelerated by the venturi operation of the gaps 216, 217. Hereby, the shield plate 210 fulfills a temperature regulating function. When the surroundings are warm, and particularly when the camera 1 is irradiated by solar light, the temperature of the shield plate 210 increases. The shield plate 210 then heats the air in the space 215, which as a result wants to rise, which air flow is accelerated by the venturi operation. The air flowing along the side wall 130, which is sucked in through the lower gap 216 and discharged through the upper gap 217, has a cooling effect on the side wall 130. Preferably, the shield plate 210 is adapted for a warming up as quickly as possible, and for a good heat transferring contact with the air in the space 215. In order to stimulate the heating by solar light, the light absorption of the outer surface of the shield plate 210 is preferably increased and the reflection is preferably lowered. For this reason, the outer surface of the shield plate 210 is preferably provided with a dark color paint, in a mat implementation. In order to stimulate the transfer of heat from the shield plate 210 to the air in the space 215, the shield plate 210 is preferably provided with vertically directed ribs on its inner surface.

When the ambient air cools down and the irradiation of solar light decreases, as in the evening and during the night, the flow of the air in the space 215 stops. The motionless air forms a thermal buffer between the side wall 130 and the outside air, such that the cooling down of the housing 100 is slowed down .

All in all, temperature variations of the housing 100 are thus reduced by the presence of the shield plate 210. In this context it is noted that the housing 100 is preferably implemented from aluminium plate with a thickness of some millimeters, in the order of about 5 millimeter, such that the housing 100 has a relatively large thermal mass and therefore warms up and cools down slowly, which also contributes to counter acting temperature variations .

According to an other important aspect, the upper wall 120 of the housing 100 is cooled by a forced air flow. To this end, the upper wall 120 is provided with at least one air channel 123 directed in the longitudinal direction of the housing 100. In a preferred embodiment, the upper wall is implemented double- walled. In the embodiment shown, the side walls 130, 140 have wall parts 131, 141 extending above the upper wall 120, which wall parts form side walls of the air channel 123. A lid 122 connected to the upper ends of these wall parts 131, 141 forms the upper wall of the air channel 123, and the upper wall 120 of the inner space 170 forms the lower wall of the air channel 123. At the rear side of the housing 100, a ventilator unit 125 (figure 2) is arranged, mounted against the rear wall 150. The rear wall 150 lies recessed with respect to the rear ends of the side walls 130, 140, such that the side walls 130, 140 extend backwards beyond the ventilator unit 125. The lid 122 also extends beyond the ventilator unit 125, substantially as far as the side walls 130, 140. Thus, the rear ends of the side walls 130, 140 together with the rear wall 150 and the rear end of the lid 122 define a ventilator chamber 124, in which the ventilator unit 125 is arranged. This ventilator chamber 124 is closed at its rear side by a ventilator chamber lid 127, attached to the rear ends of the side walls 130, 140. A horizontal cross partition 126 divides the ventilator chamber 124 into a lower chamber 124A and an upper chamber 124B, the ventilator unit 125 being mounted such that its suction side is located in the lower chamber 124A and that its blow side is located in the upper chamber 124B. The bottom 160 of the housing extends rearwards less far than the side walls 130, 140, and preferably does not extend beyond the rear wall 150, such that, between the lower end of the lid 127 and the rear wall 150, a gap 128 remains free defining an entrance for the ventilator chamber 124, through which the lower chamber 124A is in connection with the surroundings for drawing in air. Placing the entrance gap 128 at the lower side of the housing 100 has among other things as advantage that direct entry of rain is avoided. The upper chamber 124B exclusively communicates with the air channel 123. Thus, .the air sucked in by the ventilator 124 will be forced to flow along the upper wall 120 through the air channel 123 towards the front side of the housing 100 and to leave the air channel 123 there through an outlet opening 129. Already when no air flow occurs in the air channel 123, this air channel 123 forms a thermal insulation of the upper wall 120. The forced air flow in the air channel 123 moreover provides an active cooling. For a good heat exchange with the air flow, the upper wall 120 preferably is provided with longitudinal ribs 121 at its upper surface (only shown partially in figure 3) .

If desired, a Peltier element can be attached to the upper wall 120 for an increased cooling capacity.

The ventilator unit 125 can be in operation continuously. It is however also possible that a temperature sensor is provided, and that the ventilator unit 125 is switched ON or OFF on the basis of the temperature measured in the housing.

It is noted that camera housings are known per se in which an active cooling is provided by means of a forced air flow in the interior 170 of the housing. Such internal air flow, however, has as disadvantage that the interior 170 necessarily is in open connection with the surrounding atmosphere, such that moisture can penetrate the interior 170. Further, when sucking in outside air, dust and dirt particles will be sucked along, such that the interior 170 becomes dirty with time. These effects are disadvantageous for the good operation of the electronics and the -image pick-up chip. These problems are avoided by the forced external air flow. Particularly, the interior 170 can be closed hermetically, in which case it is preferred that one or more molecular filter units are arranged in one or more of the walls and/or the bottom, as described in Dutch patent 1029975.

An other important aspect of the camera 1 involves control of the atmosphere in the interior 170 of the housing 100. As a consequence of temperature fluctuations, condensation might be formed on the viewing glass 112 and/or on a lens of the lens system; in order to counter act this, it would be desirable to accommodate a heating element in the housing 100. On the other hand, for a good image quality it is desirable that the temperature of the image pick-up chip is kept as low as possible.

Also for this problem, the present invention offers a solution by dividing the interior 170 of the housing 100 into two thermally separated zones, as will be explained with reference to figure 6.

Figure 6 is a schematic top view of the camera 1, with the lid removed, such that the schematic arrangement of some important components is shown. A separation wall 350 is arranged in the interior 170, at a relatively short distance from the front wall 110 and substantially parallel to this front wall 110, although this parallelism is not essential. The separation wall 350 makes good connection to the bottom 160, the side walls 130, 140 and the upper wall 120, such that the interior 170 is subdivided into two separate spaces 171 and 172. The space located between the front wall 110 and the separation wall 350 will be indicated as front space 171, while the space located between the rear wall 150 and the separation wall 350 will be indicated as rear space 172. An image pick-up unit 360 is mounted in the rear space 172, which pick-up unit comprises the image chip (not shown for sake of simplicity) . A lens system 300 is located between the image pick-up unit 360 and the viewing opening 111, which system projects the light received through ^■ the viewing opening 111 onto the image chip in a suitable manner. The lens system 300 has a lens house 305 with an entrance side 301 directed towards the viewing opening 111 and an exit side 303 directed towards the image pick-up unit 360. At the entrance side 301, an -entrance lens 302 is arranged, connected to the lens house 305 in an air-tight manner. At the exit side 303, an exit lens 304 is arranged, also connected to the lens house 305 in an air-tight manner. Further design details of the lens system 300 are not relevant for a good understanding of the present invention and will not be discussed.

The lens house 305 extends through the separation wall 305, such that its entrance side 301 with the entrance lens 302 is located in the front space 171 while its exit side 303 with the exit lens 304 is located in the rear space 172. The separation wall 305 connects to the lens house 305 in an air-tight manner.

A heating member 308 is arranged in the front space 171. The heating member 308 may be an^' electrical heating member of which the operation is based on ohmic heating of a resistance element, and may be provided with a temperature sensor and a controller to keep the temperature above a certain value, but these details are not essential and are therefore not shown in the figure .

Among others, these measures offer the following advantages. The viewing glass 112 and the entrance lens 302 are heated by the heating member 308, such that the formation of condensation onto these parts is avoided. The heating member 380 only needs to heat the relatively small front space 171. The image pick-up unit 360 is thermally separated from the front space 171, and therefore is not hindered by the heat delivered by the heating member 380. If desired, the image pick-up unit 360 may be provided with one or multiple cooling ventilators, for discharging heat generated by the electronics; these cooling means do not have to discharge heat generated by the heating member 380.

An other important aspect of the camera 1 involves pollution of the outer surface of the viewing glass 112 as result of weather influences. It is a known problem for cameras for use outdoors that rain drops and the stains remaining behind after drying of rain drops may seriously disturb and obstruct the view of the camera. Sometimes, one accepts this per force, but it also happens that one has the viewing windows cleaned at a regular basis, which involves high costs and still only offers a solution for a short duration. An other known solution is arranging an automatic wiper installation, wherein a wiper provided with a cleansing liquid is moved over the outer surface of the viewing glass 112. This has the disadvantages of being mechanically complicated and breakdown susceptibility, while it is still necessary to check and fill a reservoir for the cleansing liquid on a regular basis.

It is a further objective of the present invention to also substantially reduce this problem with relatively simple means.

According to an aspect of the invention, the outer surface of the viewing glass 112 is provided with a thin transparent coating of titanium oxide. Such coating has a water-repellent property, having the result that possible water drops will flow downwards faster and/or will evaporate faster, substantially without leaving behind a residue. According to an other aspect of the invention, a substantially flat air flow is guided along the outer surface of the viewing glass 112. This air flow serves multiple purposes. In the first place, this air flow operates as an air curtain forming a barrier between the viewing glass 112 and the outside atmosphere. Possible rain drops approaching the camera will be blown away by the air flow before they reach the viewing glass 112. In the second place, this air flow can remove from the outer surface of the viewing glass 112 possible rain drops which nevertheless reach the outer surface of the viewing glass, by blowing away these rain drops. In the third place, this air flow can accelerate the evaporation of possible rain drops on the outer surface of the viewing glass 112.

It is preferred that said air flow and said coating are used in combination. Thus, a system is reached that is reliable and maintenance-free to a high degree.

In principle, it is possible to generate the said air flow independently. In a special preferred embodiment, the above described flow in the channel 123 is used, such that this flow fulfills two functions: the function of cooling of the housing and the function of keeping the viewing glass clean. This preferred embodiment will hereinafter be described in more detail with reference to figure 5, which shows a schematic longitudinal section of the front part of the housing 100 at a larger scale than figure 4. Figure 5 shows the front wall 110 with the viewing opening 111, with a lens system 300 arranged in the interior 170, aligned with the viewing opening 111. The viewing opening 111 has a height and a width (i.e. perpendicular to the plane of drawing) which may mutually differ, but typically the viewing opening 111 has a circular-round contour. The viewing glass 112 is shown in this figure as being mounted against the inner surface of the front wall 110, but it should be clear that the viewing glass 112 may also lie in the plane of the front wall 110. Although the viewing glass 112 may have an optical power, the viewing glass primarily has the function of forming a transparent but air-tight sealing of the viewing opening 111, wherein the connection of the viewing glass to the front wall 110 is air-tight. Figure 5 further shows that the front wall 110 in the height direction extends to the lid 122, while the upper wall 120 extends to the front wall 110. The part 310 of the front wall 110 positioned above the upper wall 120 forms a front wall of the flow channel 123, and is provided with a gap 311 extending over at least the full width of the viewing opening 110, fulfilling the function of the exit opening 129 mentioned with reference to figure 4. Preferably, this gap 311 extends over substantially the entire width of the front wall 110. The height of the gap.311 preferably, and as shown, is smaller than the height of the flowing channel 123.

On the outside, the front wall 110 is provided with a flow guide 320. The flow guide 320 has a guide surface 322 directed to the front wall 110, bend according to a contour to be described hereinafter. In a possible embodiment, the flow guide 320 is implemented as a bend plate. In general sense, the flow guide 320 extends in vertical direction, at a short distance of the front wall 110 and over the entire height of the front wall 110 or at least over the entire height of the viewing opening 110. The space between the flow guide 320 and the front wall 110 will be indicated as curtain space 323. The said gap 311 forms the entrance to the curtain space 323. In width direction, the curtain space is limited by the front parts of the side walls 130, 140, which extend beyond the front wall 110, as can be seen in figures 1 and 2.

The flow guide 320 has an upper end 324 connected to the front wall 110 at a location above the gap 311. At this location, the guiding surface 322 is substantially perpendicular to the front wall 110. The guiding surface 322 then has a curve section 325 bent downwards, a mid section 326 extending in front of the viewing opening 111, and an end section 327. The mid section 326 is directed substantially vertically, or (as shown) makes an angle with the vertical such that the lower side of the mid section is closer to the front wall 110 than the upper side of the mid section. The end 327 can be bent away from the front wall, as shown, such that the guiding surface as a whole has an S-shaped contour. The shortest distance between the end section 327 and the front wall 110 is larger than zero, such that, between the end section 327 and the front wall 110, a gap 328 remains that forms the exit of the curtain space 323.

The horizontal air flow AFl in the air channel 123 passes the gap 311 and is bent by the curve section 325 to a vertical curtain flow AF2, which leaves the curtain space 323 at the lower side through gap 328. Because, in the downwards direction, the curtain space 323 becomes narrower, an acceleration and lowering of pressure occurs in the curtain flow AF2, which contributes to the cleansing of the viewing glass 112.

The flow guide 320 has an opening 321 aligned with the viewing opening 111 in the front wall 110. Also this opening 321 is preferably, as illustrated in figure 1, circularly round, and its diameter corresponds substantially to the diameter of the viewing opening 111 or is somewhat larger, taking account of the viewing angle of the lens system 300, such that the viewing field of the lens system 300 is hardly or not hindered by the flow guide 320. The mid section 326, comprising the opening 321, is preferably planar. The relatively large opening 321, necessary to allow the camera viewing without obstacles, has hardly or no disadvantageous effect on the curtain flow AF2, because, as a result of the Coanda effect, the curtain flow AF2 has the tendency to follow the front wall 110 and the viewing glass 112 in stead of leaving the curtain space 323 through the opening 321: so to speak, the curtain flow AF2 "sticks" to the viewing glass 112. The ventilator unit 125 may be in operation continuously, so that the curtain flow AF2 is present continuously. However, the curtain flow AF2 is actually only needed when it rains. Therefore, it is also possible that a rain sensor is provided, and that the ventilator unit 125 is switched ON or OFF on the basis of rain being detected or not.

Figure 5 further shows that the lid 122 extends in the longitudinal direction beyond the front wall 111 and even beyond the flow guide 320, and ends with a front section 122A bent downwards. This front section 122A serves as rain shield. The side walls 130, 140 extend to the front section 122A, as visible in figure 1, in order to serve as rain shield in lateral direction. A recess 122B in the front section 122A prevents the rain shield from obstructing the view of the camera.

Summarizing, a camera (1) is described, comprising a camera housing (100) , which is provided with shield plates (210, 220) mounted along the side walls (130, 140) and a channel (123) arranged against the upper wall (120) at the outside for a forced air flow (AFl) for controlling the temperature. In the front wall (110), a viewing opening (111) with a viewing glass (112) is located, provided at the outer side with a water- repellent coating of titanium oxide. At the front side of the camera housing, the air flow is bent and guided along the viewing glass. The interior (170) of the camera housing is subdivided into two thermal zones (171, 172), wherein the image pick-up chip is arranged in the rear zone while the front zone is provided with heating means for heating the viewing glass and the entrance lens of the lens system.

It will be clear to a person skilled in the art that the invention is not limited to the exemplary embodiments discussed in the above, but that several variations and modifications are possible within the protective scope of the invention as defined in the attached claims .

Claims

1. Camera housing (100), comprising: a front wall (110) with a viewing opening (111), an upper wall (120), side walls (130, 140), a rear wall (150) and a bottom (160); wherein the housing (100) is provided with an external temperature shield (200) comprising at least one shield plate (210, 220), associated with a side wall (130, 140); wherein the height of the shield plate (210, 220) corresponds to the height of the _ corresponding side wall (130, 140); wherein the length of the shield plate (210, 220) corresponds to the length of the corresponding side wall (130, 140) or preferably is somewhat larger than the length of the corresponding side wall (130, 140); wherein the shield plate (210, 220) is mounted at a short distance of the corresponding side wall (130, 140) by means of distance holders (212), wherein the distance (dl) between a lower edge (213) of the shield plate (210, 220) and the corresponding side wall (130, 140) is larger than the distance (d2) between an upper edge (214) of the shield plate (210, 220) and the corresponding side wall (130, 140) .

2. Camera housing according to claim 1, wherein the shield plate (210, 220) in vertical direction is implemented in a concave manner, such that the mutual distance between the shield plate (210, 220) and the corresponding side wall (130, 140) has a maximum that is reached at a vertical position between the lower edge (213) and the upper edge (214), preferably about midway between the lower edge (213) and the upper edge (214).

3. Camera housing according to claim 1 or 2, wherein a distance holder (212) is implemented as a vertically directed, elongate ridge extending over a large part of the height of the side wall, preferably over the entire height of the side wall.

4. Camera housing according to claim 3, wherein each side wall is provided with two of such elongate distance holders (212) , of which one is positioned close to the front side of the side wall while the other is positioned close to the rear side of that side wall.

5. Camera housing according to any of the previous claims, wherein the outer surface of the shield plate (210) is implemented dark and mat for increasing the absorption of solar radiation.

6. Camera housing according to any of the previous claims, wherein the inner surface of the shield plate (210) is provided with vertically directed ribs .

7. Camera housing (100), preferably implemented according to any of the previous claims, comprising: a front wall (110) with a viewing opening (111), an upper wall (120), side walls (130, 140), a rear wall (150), and a bottom (160); wherein the housing (100) is provided with means (125; 123) for effecting a forced air flow (AFl) along the outer surface of the upper wall (120) for cooling the upper wall (120) .

8. Camera housing according to claim 1, provided with at least one air channel (123) directed in the longitudinal direction of the housing (100) and a ventilator (125) arranged at the rear wall (150), of which an exit communicates with the air channel (123); wherein an upper surface of the upper wall (120) forms the lower wall of the air channel (123) .

9. Camera housing according to claim 8, wherein the upper surface of the upper wall (120) is provided with longitudinal ribs (121) .

10. Camera housing according to claim 8 or 9, wherein the side wall (130, 140) have wall parts (131, 141) extending above the upper wall (120) , which form side walls of the air channel (123), and wherein a lid (122) connected to the upper ends of those wall parts (131, 141) forms the upper wall of the air channel (123) .

11. Camera housing according to claim 10, wherein the side walls (130, 140) and the lid (122) extend backwards beyond the rear wall (150) and thus, together with the rear wall (150), define a ventilator chamber (124) in which the ventilator unit (125) is arranged; wherein further a ventilator chamber lid (127) is provided, connected to the rear ends of the side walls (130, 140), for closing the ventilator chamber (124) at the rear side; wherein the housing (100) further has a horizontal partition (126) dividing the ventilator chamber (124) in a lower chamber (124A) and a upper chamber (124B), wherein the upper chamber (124B) exclusively communicates with the air channel (123), and wherein the ventilator unit (125) is mounted such that its suction side is located in the lower chamber (124A) and that its blow side is located in the upper chamber (124B) .

12. Camera housing according to claim 11, wherein the ventilator chamber (124) at its lower side has an entrance gap (128) .

13. Camera housing according to any of the claims 8-12, further provided with a temperature sensor for measuring the temperature in or of the housing, wherein further switching means are provided for switching the ventilator ON or OFF on the basis of the measured temperature.

14. Camera housing (100), preferably implemented according to any of the previous claims, comprising: a front wall (110) with a viewing opening (111), an upper wall (120), side walls (130, 140), a rear wall (150), and a bottom (160); and a viewing glass (112) mounted in or against the viewing opening (111) ; wherein the outer surface of the viewing glass (112) is provided with a thin transparent and water-repellent coating.

15. Camera housing according to claim 14, wherein the coating comprises titanium oxide.

16. Camera housing (100), preferably implemented according to any of the previous claims, comprising: a front wall (110) with a viewing opening (111), an upper wall (120), side walls (130, 140), a rear wall (150), and a bottom

(160); and a viewing glass (112) mounted in or against the viewing opening (111) ; wherein the camera housing (100) further is provided with means (123, 125, 320) for generating a air flow (AF2) and guiding this air flow along the outer surface of the viewing glass (112).

17. Camera housing according to claim 16, comprising at least one air channel (123) arranged above the upper wall (120) and directed in the longitudinal direction of the housing (100) as well as a ventilator (125) arranged at the rear wall (150) of which an exit communicates with the air channel (123); and a flow guide (320) arranged at a short distance of the front wall (110) and extending over at least the entire height of the viewing opening (111), with a guiding surface (322) directed towards the front wall (110), which is bent according to an S- shaped contour, which flowing guide (320) is provided with an opening (321) aligned with the viewing opening (111) in the front wall (110) .

18. Camera housing according to claim 17, wherein the flowing guide (320) is implemented as a bent plate.

19. Camera housing according to claim 17 or 18, wherein the flow guide (320) has an upper end (324) arranged at short distance above an exit opening (311) of the air channel (123); wherein the guiding surface (322) has a downwards bent curve section (325) extending in front of said exit opening (311), a preferably planar mid section (326) extending in front of the viewing opening (111), and an end section (327) .

20. Camera housing according to claim 19, wherein the mid section (326) makes an angle with the vertical such that the lower side of the mid section is closer to the front wall (110) than the upper side of the mid section in order to thus converge the air flow.

21. Camera housing according to claim 19 or 20, wherein the end section (327) is bent away from the front wall.

22. Camera housing according to any of the claims 19-21, wherein the shortest distance between the end section (327) and the front wall (110) is larger than zero.

23. Camera housing according to any of the claims 19-22, wherein the front wall (110) in the height direction extends beyond the upper wall (120) such that the part (310) of the front wall (110) located above the upper wall (120) forms a front wall of the flow channel (123), which part (310) is provided with a gap (311) extending over at least the full width of the viewing opening (111), which gap fulfills the function of exit opening of the flow channel (123) .

24. Camera housing according to any of the claims 17-23, further provided with a rain sensor and switching means for switching the ventilator ON or OFF on the basis of detected rain.

25. Camera (1), comprising a camera housing (100) according to any of the previous claims.

26. Camera (1), preferably according to claim 25, comprising a camera housing (100) that comprises a front wall (110) with a viewing opening (111) and a viewing glass (112) mounted in or against the viewing opening (111), an upper wall (120), side walls (130, 140), a rear wall (150), and a bottom (160), wherein the camera housing (100) further comprises a separation wall (350) , arranged at relatively short distance from the front wall

(110) and subdividing the interior (170) of the camera housing

(100) into two spaces (171) and (172) thermally separated from each other; wherein the camera (1) further comprises an image pick-up unit

(360) arranged in the rear space (162) between the rear wall

(150) and the separation wall (350) ; wherein the camera (1) further comprises a lens system (300) arranged between the image pick-up unit (360) and the viewing opening (111), which lens system (300) comprises a lens house

(305) with an entrance lens (302) and an exit lens (304) ; wherein the lens house (305) extends through the separation wall

(350); wherein the exit lens (304) is located in the rear space (172) while the entrance lens (302) is located in the front space

(171) between the front wall (110) and the separation wall

(350); and wherein a heating member (380) is arranged in the front space (171) for heating the viewing glass (112) and the entrance lens (302) .

27. Camera according to claim 26, wherein the lens house (305) connects to the separation wall (350) in an air tight manner; wherein the entrance lens (302) connects to the lens house (305) in an air tight manner; and wherein the exit lens (304) connects to the lens house (305) in an air tight manner.