JP2003348441A - Television camera for supervision - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a television camera for supervision capable of photographing an object under a local back light or with local high contrast without saturating a video signal even when the television camera is inexpensive. <P>SOLUTION: The television camera for supervision is selectively provided with an optical filter such as an ND filter 15 for reducing a transmission luminous quantity of light from a supervised area in front of a lens. Provision of the ND filter 15 can photograph an object by reducing the transmission luminous quantity of the supervised area even when the light from the supervised area is locally back lit or has locally very high contrast so as to supervise the object with a video image without 'white decay'. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surveillance television camera device installed on a platform of a train station, and more particularly, to an image of a subject having a strong backlight or a high contrast without being saturated with a video signal. The present invention relates to a surveillance television camera device.

[0002]

2. Description of the Related Art Surveillance television camera devices are widely used for monitoring platforms at stations and for security at convenience stores and banks. Relatively inexpensive TV cameras of this type are used, and the subject to be monitored includes places where backlight or contrast is extremely strong. It cannot be avoided. When shooting is performed under such high-contrast shooting conditions, there is a possibility that it is difficult to display an image of a subject due to the limitation of the dynamic range due to the characteristics of the signal processing circuit and the like of the television camera.

In a television camera of this type, when a part where the distribution of the amount of light of the light incident on the lens from the monitoring area is large and a part where the distribution is small, the lens aperture is normally adjusted to the part where the amount of light is small. The video signal corresponding to many places reaches saturation, and the image of that part flies white on the monitor image, so-called "white loss" phenomenon,
This will hinder monitoring work.

[0004] Such a phenomenon is often observed when a monitoring television camera device is installed on a station platform to monitor vehicles and passengers. For example, FIG. 4A shows a monitor screen in which a vehicle stopped at the station platform is photographed, and the area 41 at the upper right of the screen is white and an image is skipped, and “white loss” occurs. In this area 41, the vehicle and the passenger cannot be confirmed.

For a subject in which such a phenomenon occurs, the problem can be easily solved by using a high-performance camera having a high dynamic range. But,
The number of TV cameras used for monitoring passengers on the usual station platform is large, and the monitoring is performed throughout the day. Therefore, a small and inexpensive television camera is used in consideration of cost.

[0006] This kind of surveillance television camera device cannot solve the phenomenon of “white loss” due to the function provided in the device itself. The following countermeasures were taken.
The first measure is to install a light-blocking hood on the front of the camera housing, hang it from the ceiling of the station platform, and install it at a position that looks down on passengers. Adjustment of the installation angle that deviates from the imaging range is performed. The second measure is to adjust the aperture of the lens to the close side for high contrast, or to adjust the photometry of the lens to the peak side, thereby suppressing the luminance level of the captured video signal to a low level, It is devised so that a region having a lot of images can be kept within the photographable range.

[0007]

However, in the above-mentioned conventional surveillance television camera device, when the first and second measures are implemented, the first measure means that an area with a large amount of light is out of the surveillance area. However, a blind spot occurs in the monitoring area, which is not preferable. Further, in the second measure, when the lens aperture and the like are adjusted to an area having a large amount of light, the entire monitor screen becomes dark, and the dynamic range of the area having a small amount of light becomes insufficient. That is, it means that the visibility of the monitoring area is deteriorated, and there is a problem that the monitoring of the station platform at night is hindered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and even when an inexpensive television camera is used, an image signal is captured without saturating a video signal for a subject having a strong backlight or a high contrast. It is an object of the present invention to provide a surveillance television camera device that can perform the monitoring.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and the invention of claim 1 is to provide an optical filter on the front surface of a lens for reducing the amount of light passing from a monitoring area. A surveillance television camera device selectively provided.

According to the first aspect of the present invention, the monitoring area (subject)
An optical filter that reduces the amount of light passing through the lens is selectively attached to the front surface of the lens. By this optical filter, light having a large amount of light passing from a monitoring area including a subject that is backlight or has a very strong contrast is provided. It is possible to provide a surveillance television camera device capable of taking pictures with a television camera by reducing the number of images and to reliably photograph a surveillance area. In addition, the optical filter is formed on the inner surface of a protective transparent plate provided on the front surface of the lens of the TV camera body, for example, so that the TV camera body and the lens can be protected. On the other hand, it is possible to shoot an image without "whiteout".

According to a second aspect of the present invention, an optical filter for reducing the amount of light passing through the monitoring area corresponding to the image area where the video signal reaches saturation when the monitoring area is photographed is selected on the front surface of the lens. It is a surveillance television camera device characterized by being attached.

According to the second aspect of the present invention, the monitoring area (subject)
Is converted to a video signal by shooting with a TV camera, and when the video based on the video signal is projected on the monitor screen, the image area where "white loss" occurs on the monitor screen, that is, the video area where the video signal reaches saturation Correspondingly, an optical filter for reducing the amount of light passing from the monitoring area is selectively provided on the front surface of the lens. The image area where the image signal reaches saturation is an area where backlight or contrast is extremely strong. The amount of light from such an area is selectively reduced by providing an optical filter on the front of the lens, Has the effect that even in the case of a television camera body having a narrow dynamic range, it is possible to reliably capture an image of a monitoring area.

The invention according to claim 3 is the surveillance television camera device according to claim 1 or 2, wherein the optical filter is an ND filter.

According to the third aspect of the present invention, the optical filter is an ND filter, and backlight from the subject or light from a region having a very high contrast is selectively incident on the lens through the ND filter, thereby improving visibility. Images can be output to a monitor screen. That is, ND
The filter has a function of uniformly reducing the amount of light in the entire wavelength range. By selectively providing an ND filter, even if the light from the subject has a partially high contrast, the light from this region can be reduced. By reducing the amount of light passing through, it is possible to output an image without "whiteout" on the monitor screen.

The invention according to claim 4 is characterized in that the optical filter is fixed by fixing means having a position adjusting mechanism for positioning the optical filter in a region where the amount of incident light is large. It is a surveillance television camera device of the description.

According to the fourth aspect of the present invention, there is provided a fixing means having a position adjusting mechanism for adjusting the position of the optical filter in a region where the amount of incident light is large, and the position of the optical filter is set by the position adjusting mechanism. Thus, a fixing means for fixing the position is provided. The position adjustment mechanism is provided in a housing for housing the TV camera main body, the housing of the TV camera main body, a lens unit, or the like, and sets the position of an optical filter provided on the front surface of the lens to “white crush”.
There is a fixing means to set in the light passing area on the front of the lens corresponding to the light passing area where the light is generated, and fix the position, check the image on the monitor screen and set the optical filter at the optimal position Can be fixed. In addition,
The position adjustment mechanism is an optical filter slide mechanism, X
It includes a sliding mechanism in the Y direction, a rotating mechanism, a detachable mechanism, and the like.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a surveillance television camera device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a monitoring television camera apparatus according to the present invention. In the surveillance television camera device of the present embodiment, as shown in FIG. 1, a television camera body in which a lens unit 14 is mounted on a housing 10 is housed. A transparent front acrylic plate 12 that protects the lens unit 14 and the television camera body from dust, dirt, external impact, and the like is provided on the front open end of the housing 10 by the hinge 11 on the front surface of the housing 10. . The front acrylic plate 12 is provided with a light shielding plate 16 except for a light incident portion 12a on which light from a subject enters. An ND filter (Neutral) for adjusting the amount of light incident on the lens is provided on the light incident portion 12a.
Density Filter) 15 is selectively provided. Further, a light-shielding hood 13 that prevents strong light such as illumination light or direct sunlight from directly irradiating the lens is provided so as to cover the housing 10.

More specifically, the housing 1
A light-shielding plate 16 is provided on the front acrylic plate 12
The portion partitioned by the light shielding plate 16 is a light incident portion 12a on which light from the monitoring area (subject) is incident, and has a sufficient area for light from the monitoring area to enter. Further, the light shielding plate 16 prevents light incident from the light incident portion 12a from being irregularly reflected in the housing 10. An ND filter 15 is attached to the inner surface of the front acrylic plate 12 of the light incident portion 12a to selectively reduce the amount of light incident from the light incident portion 12a so that the light enters the lens of the lens unit 14. I have. The amount of light passing through the light incident portion 12a without the ND filter 15 is transmitted through the acrylic plate without being reduced, and is not reduced.
Incident on the lens. In the present embodiment, the ND filter 15 is provided at the upper left corner of the light incident part 12a.

Since the position where the ND filter 15 is attached differs depending on the subject, after installing the monitoring television camera device, the image of the monitoring area is checked on the monitor screen.
The ND filter 15 is attached to the light passage area of the light incident portion 12a corresponding to the area where “whiteout” occurs. Subsequently, it is checked whether or not the occurrence of the “white loss” has been eliminated on the monitor screen, and the attachment position of the ND filter 15 is fixed. Incidentally, the ND filter 15 can be attached by attaching the ND filter 15 to the back side of the front acrylic plate 12 of the light incident portion 12a with a double-sided tape or the like.

The ND filter 15 is a filter that functions to uniformly reduce the amount of light passing through the ND filter 15 over the entire wavelength range, and has a locally high contrast (contrast including a backlight is extremely high). The amount of light can be reduced evenly with respect to a subject that has a strong light regardless of the wavelength, and an image with good visibility without "whiteout" can be displayed on the monitor screen.

Next, the operation of this embodiment will be described with reference to FIG.
This will be described with reference to (a) to (c). FIG.
(C) is an image when the station platform is photographed by the monitoring television camera device.

FIG. 4 (a) shows an image in the case where the ND filter 15 described in the conventional example is not provided. , The luminance signal becomes higher than a predetermined level, the so-called video signal becomes saturated, and an image without shading is obtained. In such an image, the station attendant cannot see the leading or trailing vehicle of the train, and a red light confirming the opening / closing of the door is provided on the side of the train in the area 41 that has been crushed by white. Although it is provided, the blinking of the red light cannot be confirmed. Therefore, the station clerk cannot confirm the opening and closing of the train door from this image, and cannot protect the safety of passengers.

FIG. 4B shows the monitoring television camera apparatus of the present embodiment provided with the ND filter 15,
It is a video of the same photographing place as in FIG. This image shows a case where an ND filter 15 is provided at the upper left corner toward the light incident portion 12a. The shooting area shot through the ND filter 15 corresponds to the area 42 at the upper right corner on the monitor screen. This area 42 corresponds to FIG.
As is clear from the image in FIG. 4B, the area 41 in FIG. 4A has been “blown out”. However, the addition of the ND filter 15 has improved the vehicle to the extent that the vehicle can be confirmed. The red light provided in the section can be checked, and the station attendant can monitor the vehicle and passengers by monitoring this image to protect the safety of passengers.

On the other hand, FIG. 4 (c) shows the same place photographed at night, and the part corresponding to the area 41 that has been "blown out" is the area 43. Even if the ND filter 15 is attached, the area 43 is photographed at night. The image is not too dark, and is an appropriate image that allows the user to check the vehicle and passengers, so that the station staff can protect the safety of passengers.

Next, another embodiment of the present invention will be described with reference to FIGS. 2 and 3 show an embodiment in which the monitoring television camera device is not provided in the housing, and this embodiment shows an embodiment in which the camera is installed indoors at a convenience store or a bank other than the station platform. ing. Even when the monitoring television camera device is installed indoors, when monitoring a window or an entrance, there is a monitoring area (subject) where light from the outside is incident. It is effective for

First, the embodiment of FIG. 2 will be described. The ND filter 23 is provided at the front end of the fixing bracket 22, and the rear end of the fixing bracket 22 is fixed to the housing of the camera body 21. Reference numeral 23 is attached to the front surface of the lens of the lens unit 14. The fixing bracket 22 can be fixed by various attachment / detachment mechanisms such as screwing and fitting. The fixing means of the ND filter 23 by this attachment / detachment mechanism has a function of fixing the ND filter 23 at a position where the amount of the local backlight or the light with very strong contrast in the monitoring area can be reduced.

FIG. 2 shows the fixing means by the fixing fitting 22 in a simplified manner, but has a position adjusting mechanism for the ND filter 23 and a fixing mechanism for fixing the position. The position adjusting mechanism may be configured to be able to finely adjust the position of the ND filter by a slide mechanism, a rotating mechanism, or the like. The largest cause of high contrast is backlight or sunlight reflection, which tends to occur above the image. Therefore, the attachment / detachment mechanism for the fixture 22 should be provided in consideration of these factors.

For setting the position of the ND filter 23, a position adjusting mechanism (not shown) having a rotating mechanism for rotating the fixing bracket 22 about the optical axis of the lens unit 14 may be provided. In this position adjusting mechanism, the ND filter 23 may be rotated by rotating the fixture 22 by the rotating mechanism, and the ND filter 23 may be adjusted to a position where the amount of incident light is reduced. Further, as the position adjusting mechanism, for example, a ring-shaped member is used, and a fixing member 22 provided with an ND filter 23 is fixed to the ring-shaped member, and the ND filter 23 is rotated by rotating the ring-shaped member. Then, the ND filter 23 may be fixed by setting a position where the amount of light in a region of backlight or light having very strong contrast from the subject can be reduced.

Next, the embodiment shown in FIG. 3 will be described.
In the figure, an ND filter 32 is attached inside the clear filter 31, and the clear filter 31 is fitted on the front surface of the lens of the lens unit 14, and the clear filter 31 is fixed to the lens unit 14. The ND filter 32 can be set at an arbitrary position in the circumferential direction by rotating the clear filter 31 about the optical axis of the lens unit.

As a position adjusting mechanism of the ND filter, a lens front of a lens unit of a television camera is provided.
An ND filter may be provided on a transparent plate such as an acrylic plate to provide a position adjusting mechanism that can slide the transparent plate in the XY directions. The transparent plate is slid in the X and Y directions to align the ND filter attached to the transparent plate at an appropriate position, and then the transparent plate is fixed by fixing means using screwing or friction, and the ND filter is mounted on the lens. It may be fixed at an appropriate position on the front surface. The appropriate position is a position where light from the monitoring area is locally backlit or light with high contrast passes through the transparent plate.
Even if the amount of light passing through the D filter) enters the lens, a clear image can be obtained without saturating the image signal, without causing "whiteout", and without impeding monitoring.

The transparent plate is provided with a box-shaped or cylindrical cap-shaped base surrounding the lens unit, and on the front of the base, a transparent plate provided with an optical filter such as an ND filter is provided. The position of the optical filter may be set by sliding the plate in the X and Y directions. As the position adjusting mechanism of the optical filter, various mechanisms such as a sliding mechanism, an XY sliding mechanism, a rotating mechanism, and an attaching / detaching mechanism using a fitting member can be implemented.

In the above-described embodiment, an optical filter such as a gradation ND filter, a UV filter, a color conversion filter, or a deflection filter can be used as the optical filter, depending on the monitoring target, in addition to the ND filter. Furthermore, depending on the optical properties of the subject, these optical filters may be combined in a complex manner on a transparent plate in front of the lens. For example,
When the amount of light of a specific wavelength from the monitoring area is large, the amount of light of the specific wavelength is reduced and taken into a lens, so that an image in which the occurrence of “whiteout” has been eliminated can be displayed on a monitor.

FIGS. 2 and 3 show another embodiment.
May be housed in the housing. In this case, since the ND filter is provided on the front surface of the lens of the television camera, it goes without saying that it is not necessary to attach the ND filter to the front acrylic plate.

[0035]

As described above, according to the present invention,
By selectively providing an optical filter that reduces the amount of light incident on the lens, even if an inexpensive TV camera with a not so wide dynamic range is used,
Covering the performance, it is possible to obtain an appropriate image for a subject with extremely strong backlight or contrast without saturating the image signal.
Since a video with good visibility can be obtained even during nighttime shooting, there is an advantage that the monitoring area can be monitored on a monitor screen all day.

According to the present invention, even when the light amount of a specific wavelength is large, similarly, by selectively providing an optical filter other than the ND filter, the image is taken with the light amount of the wavelength reduced. Thus, there is an advantage that the monitoring area can be monitored by an image in which “whiteout” does not occur.

Further, according to the present invention, there is an advantage that an optical filter can be easily installed even in an already installed surveillance television camera device, and an advantage that the surveillance television camera device can be provided at low cost. There is.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of a monitoring television camera device according to the present invention.

FIG. 2 is a perspective view of another embodiment of the monitoring television camera apparatus according to the present invention.

FIG. 3 is a perspective view of another embodiment of the monitoring television camera device according to the present invention.

FIG. 4A is a photographing screen of a monitoring area (station platform) in which the whiteout has occurred, FIG. 4B is a photographing screen of a monitoring area in daytime, and FIG. 4C is a photographing screen of nighttime.

[Explanation of symbols]

101 Housing 11 Hinges 12 Front acrylic board 12a Light incidence part 13 Shading hood 14 Lens unit 15, 23, 32 ND filter 16 Shade plate 21 Camera body 22 Fixing bracket 31 Clear filter

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Claims (4)

[Claims] 1. A surveillance television camera apparatus, wherein an optical filter for reducing the amount of light passing through a surveillance area is selectively provided on the front surface of a lens. 2. An optical filter for reducing the amount of light passing from the monitoring area corresponding to the image area where the video signal reaches saturation when the monitoring area is photographed, is selectively provided on the front surface of the lens. Surveillance television camera device. 3. The surveillance television camera device according to claim 1, wherein the optical filter is an ND filter. 4. The surveillance television camera device according to claim 1, wherein the optical filter is fixed by fixing means having a position adjusting mechanism for positioning the optical filter in a region where the amount of incident light is large. .