US20080072393A1

US20080072393A1 - Wiper Device for Dome

Info

Publication number: US20080072393A1
Application number: US11/793,932
Authority: US
Inventors: Kenichi Tanaka
Original assignee: Tanaka Machine Co Ltd
Priority date: 2004-12-24
Filing date: 2005-11-28
Publication date: 2008-03-27
Also published as: WO2006067934A1; JP2006198602A

Abstract

A wiper device for dome for cleaning a spherical clear dome window (2) arranged at the front of a housing comprises: a semi-circularly arced wiper arm (3) having rotatable structures on its both ends fitted to near the central axis of the spherical clear dome window (2) of the housing; a blow structure (17) for blowing a pressurized fluid formed inside of the wiper arm (3) which is arranged at a predetermined distance from a curved surface of the spherical clear dome window (2) without contacting with clear dome window; and a driving means for rotating the wiper arm (3) reciprocatingly as the pressurized fluid being introduced into the wiper arm from the one end of the wiper arm. As a result, the wiper device for dome can clean the spherical clear dome window arranged at the front of a housing for accommodating a TV camera, a video camera or the like installed in a building without damaging the spherical clear dome window.

Description

FIELD OF INVENTION

The present invention relates to a wiper device for cleaning a clear dome window formed at the front of a housing which accommodates TV cameras, video cameras or the like, particularly relates to a wiper device for dome of a housing having spherical clear dome window.

RELATED BACKGROUND ARTS

Wiper devices, which employ rubber wipers, for cleaning the clear dome window of such housing have been known (for example, see Japanese laid open patent Nos. 10-216049 and 10-216666).
A surveillance camera system, which accommodates a camera, a camera controlling circuit, an image amplifying circuit, a power supply circuit, mechanical units and other electronic circuits necessary for surveillance in its housing having a spherical clear dome window, is placed outdoors, particularly placed along the road, so that dirt is sticking to a surface of the clear dome window, through which image is acquired by the camera, with the passage of time or drips of water stick to the surface when it rains. In order to clean the clear dome window by rubbing the dirt or the drips off the surface, a wiper device comprising a rubber blade attached to a wiper arm is operated by the following successive operational steps. A motor is rotated so that a motor gear is rotated. The motor gear rotates the wiper arm together with the rubber blade, which sweeps the surface of the clear dome window. As a result, clear images can be acquired by the camera through the cleared window.

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

However, in the above-mentioned conventional wiper device, since a wiper element is directly attached to and cleans the clear dome window by rubbing the window, scratches are formed on the surface of the clear dome window. Once dirt gets in these scratches, it is difficult to remove the dirt by the wiper element completely. The clear dome window becomes clear temporally only after the wiper device is operated. However, the dirt or worn elements of the wiper device cause troubles, when the wiper device is operated for a long time.
Some cleaning methods, in which a pressurized air is blown from the periphery of a dome, are proposed. However, these methods are not so effective to remove dirt and drips of rain.
In order to solve problems mentioned above, the present invention proposes a wiper device for dome which can remove dirt or drops of rain stuck to a clear dome window without contacting with the window by blowing a compressed fluid such as air, water and the like in a continuous or discontinuous slits or series of aligned blow holes formed in a wiper arm, which is rotated around the clear dome window without contacting the window.

Means to Solve the Problems

The above-mentioned problems are solved by devices specified as follows.

- (1) A wiper device for dome for cleaning a spherical clear dome window arranged at the front of a housing comprising: a semi-circularly arced wiper arm having rotatable structures on its both ends fitted to near the central axis of the spherical clear dome window of the housing; a blow structure for blowing a pressurized fluid formed inside of the wiper arm which is arranged at a predetermined distance from a curved surface of the spherical clear dome window without contacting with the clear dome window; and a driving means for rotating the wiper arm reciprocatingly as the pressurized fluid being introduced into the wiper arm from the one end of said wiper arm.
- (2) The wiper device for dome according to (1), wherein: the wiper arm is rotated along the curved surface of the clear dome window reciprocatingly; the pressurized fluid is blown from the inside of the wiper arm against the clear dome window from a time when the rotating wiper arm is positioned at one end of the clear dome window to a time when the rotating wiper arm reaches a center of the clear dome window; the pressurized fluid is stopped blowing from the wiper arm from the time when the rotating wiper arm is positioned at the center of the clear dome window to a time when the rotating wiper arm reaches the other end of the clear dome window; the pressurized fluid is blown again from the wiper arm from the time when the rotating wiper arm is positioned at the other end of the clear dome window to a time when the rotating wiper arm reaches the center of said clear dome window.
- (3) The wiper device for dome according to (1), wherein: the blow structure is formed as a plurality of blow holes for blowing the pressurized fluid formed inside of the wiper arm and the blow holes are arranged such that a diameter of the blow hole is increased as the blow hole is formed farther apart from the one end where the pressurized fluid is introduced so as to equalize pressures of blown fluid from respective the blow holes against the clear dome window.
- (4) The wiper device for dome according to (1) or (2): the blow structure is formed as a continuous slit or discontinuous slits inside of the wiper arm extending from the one end where the pressurized fluid is introduced to the other end.
- (5) The wiper device for dome according to (1), wherein: the driving means which rotates said wiper arm reciprocatingly is automatically operated at predetermined times in 24 hours in order to remove dirt stuck to the clear dome window.
- (6) The wiper device for dome according to (1), wherein: the driving means which rotates the wiper arm reciprocatingly comprises a luminosity sensor; and the driving means automatically drives the wiper arm at a predetermined luminosity measured by the luminosity sensor in 24 hours in order to remove dirt stuck to the clear dome window.
- (7) The wiper device for dome according to any one of (1) to (4), wherein: a pressurized gas or a pressurized liquid is employed as the pressurized fluid; and the pressurized gas and the pressurized liquid can be blown alternatively such that the pressurized gas is switched to the pressurized liquid or vice versa.
- (8) The wiper device for dome according to any one of (1) to (4), wherein: a pulverized mixture of gas and liquid is employed as the pressurized fluid blown from the blow hole.
- (9) The wiper for dome device according to any one of (1) to (4), wherein: the pressurized fluid heated by a heater is blown from the blow hole as the hot pressurized fluid.

EFFECTS ATTAINED BY THE INVENTION

The present invention can provide the wiper device for the dome which can remove dirt or drops of rain stuck to the clear dome window for the surveillance camera constituted by spherically formed glass or resin without contacting the window by blowing the compressed fluid such as air, water and the like from continuous or discontinuous slits, or series of aligned blow holes formed in the wiper arm, which is rotated around the clear dome window without contacting the window. Even if a dome-shaped surveillance camera is arranged at a high position, the clear dome window of the surveillance camera can be kept in a clear state by operating the wiper device of the present invention. Further, even if the surveillance camera is employed in a season or a place where much dirt or many drops of rain are generated, the clear dome windows can be kept clean by periodically rotating the wiper arm according to the conditions of the season or the place. Thus image acquiring performance of the surveillance camera is kept at a minimum deterioration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory front view showing a wiper device for dome as an embodiment by the present invention.
FIG. 2 is a partially enlarged front view of the wiper device shown in FIG. 1.
FIG. 3 is a right side view of the wiper device shown in FIG. 1.
FIG. 4 is a left side view of the wiper device shown in FIG. 1.
FIG. 5 is a chart showing an operational sequence of the wiper arm.
FIG. 6 illustrates straight developed views of the wiper arm having a series of same sized blow holes: (a) is a front view; and (b) is a side view.
FIG. 7 illustrates straight developed views of the wiper arm having a series of different sized blow holes: (a) is a front view; and (b) is a side view.
FIG. 8 is a diagram illustrating control circuits of the wiper device by the present invention.
FIG. 9 is a chart showing a time-controlled operational sequence of the wiper device.
FIG. 10 is a chart showing an operational sequence controlled according to luminosity around the surveillance camera.
FIG. 11 is a front view showing another embodiment of a wiper device by the present invention.
FIG. 12 illustrates straight developed views of the wiper arm having a slit-shaped blow hole: (a) is a front view; and (b) is a side view.
FIG. 13 is a partial front view of a modified wiper arm from the wiper arm shown in FIG. 12.

PREFERRED EMBODIMENT BY THE PRESENT INVENTION

Hereinafter the best modes of the present invention are explained in detail based on the embodiments.

Embodiment

Hereinafter, the embodiment by the present invention is explained as referring to FIGS. 1-4 and 8. In the present embodiment, the wiper device is integrated into a housing of a camera dome where a TV camera or a video camera is arranged.
FIG. 1 is the front view showing the wiper device for dome integrated in a dome window. FIG. 2 is the partially enlarged front view of the wiper device illustrating flows of compressed air blown out of holes of the wiper arm in order to remove dirt stuck to the clear dome window. FIG. 3 is the right side view of the wiper device. FIG. 4 is the left side view of the wiper device. FIG. 8 is the diagram illustrating the control circuits for controlling driving means of the wiper device.
In the present embodiment, air is employed as a pressurized fluid.
FIG. 8 illustrates an example of control circuits for driving a wiper arm 3 and a compressor 6. When microswitch 12 a or 12 b is pushed by a pushing shaft 11 of the wiper arm 3, an ON-signal is inputted into a digital signal conversion circuit 27 or 28. And an OFF-signal is generated, when the microswitch is not pushed by the pushing shaft 11. The ON-signal and the OFF-signal are inputted into a CPU 21 as converted digital signals. The CPU 21 outputs instructions to a motor driving circuit 20 for controlling a motor 10 and to a compressor driving circuit 6 b for controlling a compressor 6.
A timer 22 and a memory 29 storing programs and operational steps therein, are connected to the CPU 21.
As shown these drawings, a clear dome window 2 is arranged at the front of a dome cover 1, so that the dome cover 1 and the clear dome window 2 constitute a housing which protects camera, an image amplifying circuit, control circuits constituted mainly by processors, mechanical units for driving the camera and the like.
At an inner side of a semi-circularly arced wiper arm 3, an air passage 4 for guiding air having a circular arced surface extending along a curved surface of the clear dome window 2 is formed.
The wiper arm 3 is rotatably fitted to arm shafts 5 a and 5 b arranged near a central axis of the clear dome window 2.
At one end of the wiper arm 3, an arm gear 7 is arranged and engaged with a motor gear 9. The motor gear 9 is fixed to a motor shaft 8 of a driving motor 10.
The pushing shaft 11 is fixed to the other end of the wiper arm 3. The microswitches 12 a and 12 b are arranged at right and left ends of a locus formed by the movement of the pushing shaft 11 when the wiper arm 3 is rotated around the arm shafts 5 a and 5 b, so that the microswitches are activated according to the movement of the pushing shaft 11.
The compressor 6 is arranged in the dome cover 1 and introduces compressed air to the air passage 4 via a pipe 6 a. Then the compressed air is blown from a plurality of blow holes 17 pierced through the air passage 14, so that pressurized air flows 15 are generated around the clear dome window 2 (see FIG. 2). As a result, dirt 14 or drips 14 a are removed by the pressurized air flows 15.
Hereinafter, operational steps of the wiper device constituted in the above-mentioned way are explained as referring to FIGS. 1-5 and 8.
As shown in FIG. 3, when the driving motor 10 rotates counterclockwise, the motor gear 9 is rotated in the same direction. As the rotating movement of the driving motor 10, the arm gear 7 as well as the wiper arm 3 are rotated clockwise (but the arm gear 7 is rotated counterclockwise when observed in the opposite side as shown in FIG. 4).
The compressed air is introduced from the compressor 6 via the pipe 6 a to the air passage 4 formed inside of the wiper arm 3, so that the dirt 14 and the drips 14 a from rain are removed from the whole spherical surface of the clear dome window 2, when the wiper arm 3 is rotated around the clear dome window 2.
When the wiper arm 3 is rotated around the clear dome window 2 about a half turn from position 3 a via position 3 b to position 3 c as shown in FIG. 4, the microswitch 12 a at the left side in FIG. 4 is pushed by the pushing shaft 11, so that the ON-signal from the microswitch 12 a is converted to a 4 bit or 8 bit digital signal by the digital signal converting circuit 27 as shown in FIG. 8. The converted digital signal is inputted into the CPU 21. The CPU 21 transmits an instruction to the motor driving circuit 20 so as to rotate the motor 10 in the reverse direction. Consequently, the wiper arm 3 is rotated in the reverse direction around the clear dome window 2 from position 3 c via position 3 b to position 3 a, so that the microswitch 12 b at the right side is pushed by the pushing shaft 11. The pushed microswitch 12 b outputs ON-signal and succeeding steps are carried out in the same way mentioned above, so that finally the motor 10 is rotated in the reverse direction to the present direction.
While the wiper arm 3 is rotated around the clear dome window 2 in the above-mentioned way, the pressurized air flows 15 from the plurality of the blow holes 17 formed in the air passage 4 blow against the spherical surface of the clear dome window 2 without interruption, so that the clear dome window 2 is kept clean without contacting the wiper arm 2.
Hereinafter methods for controlling the pressurized air flows 15, which are blown from the blow holes 17 and blown against the clear dome window 2, are explained as referring to FIGS. 2, 4, 5 and 8.
As shown in FIG. 4, while the wiper arm 3 is rotated from position 3 b to position 3 c, since the air from the blow holes 17 of the air passage 4 formed inside of the wiper arm 3 is blown upward, sometimes the dirt 14 is removed not so effectively. In order to solve this disadvantage, the following measure is taken. A time interval between a time when the wiper arm 3 is at position 3 a (microswitch 12 b is on) and a time when the wiper arm 3 is at position 3 c (microswitch 12 a is on) is measured by the CPU 21 and is set “h”, while the wiper arm 3 is rotated from position 3 a to position 3 c, or vice versa Since the motor 10 is rotated at a constant angular velocity, a time interval between a time when the wiper arm 3 is at position 3 a (or 3 c) and a time when the wiper arm is at position 3 b can be set ½ h and is stored in the memory 29.
Then as shown in FIG. 5, instructions to operate compressor 6 in the CPU 21 are set as follows. While the wiper arm 3 is rotated downward (namely a time interval 3 a-b from position 3 a to position 3 b or a time interval 3 c-b from position 3 c to position 3 b), instructions are set “ON”, so that the air flows 15 are blown against the clear dome window 2. On the other hand, while the wiper arm 3 is rotated upward (namely a time interval 3 b-c from position 3 b to position 3 c or a time interval 3 b-a from position 3 b to position 3 a), instructions are set “OFF”, so that the compressor 6 is stopped.
Since usually the surveillance camera is arranged at the ceiling such that the clear dome window 2 is facing the ground or the floor, operations of the wiper arm are set in the above-mentioned manners. Namely, while the wiper arm 3 is rotated from position 3 a to position 3 b, the wiper device is activated to remove the dirt 14 and the drips 14 a downwardly. On the other hand while the wiper arm 3 is rotated upwardly from position 3 b to position 3 a, the pressurized air flows 15 are stopped from being blown against the clear dome window 2, since efficiencies for removing the dirt 14 and drips 14 a are not so effective. Thus on the whole, the clear dome window 2 can be cleaned effectively.
Hereinafter methods how to equalize blowing amounts of air are explained as referring to FIGS. 6 and 7.
Actually the compressor 6 introduces compressed air to the curved air passage 4 via the pipe 6 a as shown in FIG. 1, here, however, the air passage 4 is considered to be developed as a straight passage for easier explanation.
If diameters of the blow holes 17 formed in the air passage 4 are the same, blowing amounts of air flows 15 from the respective blow holes 17 are not equal due to internal frictions of the air in the air passage 4. The blowing amounts from the respective blow holes in order are as follows: 16 a>16 b>16 c>16 d>16 n.
Since differences in blowing pressures of the respective pressurized air flows 15 fluctuate cleaning effects on respective positions blown by the air flows 15 in the clear dome window 2, blowing amounts of the air flows are varied according to degrees of the blowing pressure as shown FIG. 7. Namely, diameters of blow holes 19 a, 19 b, 19 c, 19 d and 19 n are formed such that a diameter of blow hole at lower blowing pressure is set larger than that at a higher blowing pressure, so that respective blowing amounts 18 a, 18 b, 18 c, 18 d and 18 n are set almost equal.
As explained above, the pressurized air flows 15 from the blow holes 17 arranged the air passage 4 of the wiper arm 3 are blown against the spherical surface of the clear dome window 2, so that the dirt 14 and drips 14 a can be removed effectively, since the blowing air flows 15 are equally controlled.
Hereinafter, periodical cleaning sequences are explained as referring to FIGS. 8 and 9. According to the cleaning sequences, the clear dome window 2 is cleaned periodically in order to prevent image acquiring effects of the camera from deteriorating by suppressing the dirt 14 and drips 14 from sticking to the clear dome window permanently. According to signals from a timer 22, the CPU 21 transmits instructions to the motor driving circuit 20 so as to rotate the wiper arm 3 periodically.
For example, time 25 a to start cleaning the clear window 2 is set such that the CPU 21 transmits signals to the motor driving circuit 20 and compressor driving circuit 6 b at time 25 a so as to rotate the wiper arm 3 and so as to operate the compressor 6.
If the surveillance camera is placed in an environment where the dirt 14 and drips 14 a are generated heavily, another time 25 b can be set, or a time interval to start cleaning the clear window can be set shorter, for example twice or more in 24 hours.
Thus the clear dome window 2 can be kept always clean.
As shown in FIG. 8, a luminosity sensor 23 can be arranged in the clear dome window 2 so as to detect luminosity therein. When luminosity varies as a curve 26 c depicted in FIG. 10, signals measured by the luminosity sensor 23 are converted by a digital signal converter 24 and inputted into the CPU 21. If a luminosity level to operate the wiper device is set 25 c in the CPU 21, the wiper arm 3 can be rotated automatically at point 26 a and point 26 b.
The wiper arm 3 can be rotated at lowest luminosity level or at highest luminosity level by programs installed in the CPU 21 or by one of signals of the surveillance camera.
As explained above, operations to rotate the wiper arm 3 automatically can be set at a highest or a lowest luminosity level according to luminosity changes in the clear dome window, so that the clear dome window 2 is always kept clean, in other words an image acquiring performance of the surveillance camera is not deteriorated.
In the above-explained embodiment, it is anticipated that dirt and drips at some portions of the clear dome window can not be removed completely due to a pressure difference between two neighboring blow holes, since the pressurized air is blown from a series of individual blow holes of the wiper arm as the wiper arm being rotated reciprocatingly, so that clear images can not be acquired by the camera.
In order to eliminate such pressure difference, slits are formed in the air passage of the wiper arm 3 instead of plurality of blow holes. A continuous slit 17A is formed on an air passage 4 c as shown in FIG. 12. A slit 17B discontinued by a connecting point x can be formed on an air passage 4 d as shown FIG. 13. By employing such slits formed on the wiper arm 3 from which pressurized fluid such as air, water or the like is blown as the wiper arm 3 is rotated reciprocatingly over the clear dome, a wiper device for dome which is capable of removing dirt and drips completely can be proposed, so that clear images are always provided. The connecting point x of the slit 17B reinforces the semi-circularly arced wiper arm 3.
In the above explained examples, the wiper arm is combined integrally with the clear dome window as well as the dome cover. As shown in FIG. 11, however, a wiper device can be attached to the dome cover 1.
In this embodiment, attaching portions 30, 30 are formed on both sides of the dome cover 1. Adapting elements 31, 31 rotatably supporting the wiper arm 3 are fixed to the attaching portions 30, 30 by screws or the like. Electric/electronic unit P for driving and controlling the wiper device is attached to one of the adapting element 31, and a small tank Q for storing pressurized fluid is attached to the other adapting element 31 from where a pipe is led to a compressor arranged outside. Thus the wiper device for dome can be easily assembled.
In the tank Q a heater H for heating the pressurized fluid can be arranged in order to remove stuck ice or snow to the clear dome window by blowing heated fluid from blow holes 17, slit 17A or slit 17B, so that the clear dome window is kept clean without any fogginess.
As explained above, even if the wiper devices by the present invention are employed in surveillance cameras arranged outdoor or indoors at such high positions where scaffolds are required for maintaining the surveillance cameras, the clear dome windows can be cleaned automatically and can be kept always clean by remote controls or programs installed in the CPU 21.
Since pressurized fluid is supplied from the vicinity of the clear dome windows, a high pressure is not required so that a small sized compressor is enough for the wiper device by the present invention. Further since the wiper arm by the present invention does not contact with the clear dome window directly, the clear dome window is cleaned without generating any scratches on its surface, which is one of the important features of the present invention. Further, blowing positions, blowing cycles, blowing timings depending on luminosity and the like can be installed in the CPU 21 in accordance with environmental conditions around the wiper device.
The wiper device can be operated at any time whenever it rains or much amount of dirt is formed, according to instructions from the CPU 21 in a controlling system of the surveillance camera.
In the embodiments explained above, pressurized air is employed as pressurized fluid, but pressurized liquid such as water, pulverized liquid or the like can be also employed. When the clear dome window is heavily contaminated, pressurized liquid can be used together with pressurized air. At first dirt stuck to the surface is removed by pressurized liquid and the surface is cleaned by pressurized air afterwards.
In this case, a unit to switch pressurized air to pressurized liquid or vice versa is required or respective units to supply pressurized air and pressurized liquid are required.

Claims

1. A wiper device for dome for cleaning a spherical clear dome window arranged at the front of a housing, said housing accommodating:

a camera, an image amplifying circuit, control circuits constituted mainly by processors, a mechanical unit for operating the camera, a driving unit for driving a wiper arm, a pressurized fluid generating unit and a heating unit for heating the pressurized fluid, said wipe device for dome comprising:

a semi-circularly arced wiper arm having a pressurized fluid passage for circulating the pressurized fluid and rotatable structures on its both ends fitted to near the central axis of said spherical clear dome window of said housing;

a blow structure for blowing a pressurized fluid formed inside of said wiper arm which is arranged at a predetermined distance from a curved surface of said spherical clear dome window without contacting with said clear dome window, wherein:

the pressurized fluid is introduced into said wiper arm from the one end of said wiper arm; and

the introduced pressurized fluid is blown from said blow structure against the curved surface of said clear dome window as said wiper arm being rotated reciprocatingly.

2. The wiper device for dome according to claim 1, wherein:

said wiper arm is rotated along the curved surface of said clear dome window reciprocatingly;

the pressurized fluid is blown from the inside of said wiper arm against said clear dome window from a time when said rotating wiper arm is positioned at one end of said clear dome window to a time when said rotating wiper arm reaches a center of said clear dome window;

the pressurized fluid is stopped blowing from said wiper arm from the time when said rotating wiper arm is positioned at the center of said clear dome window to a time when said rotating wiper arm reaches the other end of said clear dome window; and

the pressurized fluid is blown again from said wiper arm from the time when said rotating wiper arm is positioned at the other end of said clear dome window to a time when said rotating wiper arm reaches the center of said clear dome window.

3. The wiper device for dome according to claim 1, wherein:

said blow structure is formed as a plurality of blow holes for blowing the pressurized fluid formed inside of said wiper arm and said blow holes are arranged such that a diameter of said blow hole is increased as said blow hole is formed farther apart from the one end where the pressurized fluid is introduced so as to equalize pressures of blown fluid from respective said blow holes against said clear dome window.

4. The wiper device for dome according to claim 1:

said blow structure is formed as a continuous slit or discontinuous slits inside of said wiper arm extending from the one end where the pressurized fluid is introduced to the other end.

5. The wiper device for dome according to claim 1, wherein:

said driving means which rotates said wiper arm reciprocatingly is automatically operated at predetermined times in 24 hours in order to remove dirt stuck to said clear dome window.

6. The wiper device for dome according to claim 1, wherein:

said driving means which rotates said wiper arm reciprocatingly comprises a luminosity sensor; and

said driving means automatically drives said wiper arm at a predetermined luminosity measured by said luminosity sensor in 24 hours in order to remove dirt stuck to said clear dome window.

7. The wiper device for dome according to claim 1, wherein:

a pressurized gas or a pressurized liquid is employed as the pressurized fluid; and

the pressurized gas and the pressurized liquid can be blown alternatively such that the pressurized gas is switched to the pressurized liquid or vice versa.

8. The wiper device for dome according to claim 1, wherein:

a pulverized mixture of gas and liquid is employed as the pressurized fluid blown from said blow hole.

9. The wiper for dome device according to claim 1, wherein:

the pressurized fluid heated by a heater is blown from said blow hole as the hot pressurized fluid.