JP2005318237A - Color/monochrome switching camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent incorrect judgment at the time of switching color/monochrome. <P>SOLUTION: A monitor camera comprises a lens 1 and a CCD 4 arranged in a cabinet 2, and an infrared ray cut filter 7 or a dummy glass piece 5 is arranged selectively in a space K between the lens 1 and the CCD 4. A control means 3 delivers a signal indicating that the infrared ray cut filter 7 is arranged in te space K when the light from an object is brighter than a predetermined luminance level otherwise the dummy glass piece 5 is arranged in the space K. A photosensor 8 reacting only on the visible light in the light passed through the lens 1 is provided on te periphery of the light receiving plane 40 of the CCD 4, and the control means 3 switches arrangement of the infrared ray cut filter 7 or the dummy glass piece 5 in the space K based on the output from the photosensor 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a camera device capable of switching between color output and monochrome output, and more particularly to a surveillance camera.

Many such surveillance cameras use a CCD as a solid-state imaging device. The sensitivity characteristic of this CCD extends in the wavelength region of about 400 nm to 1000 nm, and particularly the sensitivity in the infrared region (about 700 nm or more) is high. Therefore, when light from an external subject is directly incident on the CCD, the color image output from the CCD becomes reddish. Therefore, an infrared cut filter for removing light in the infrared region is inserted between the lens and the CCD to remove the redness.
In addition, since the amount of light is large during the daytime, a good color output can be obtained from the CCD. Therefore, in order to increase the amount of light input to the CCD at night, an infrared cut filter is not used, and light including an infrared region is input to the CCD to obtain a good image. In this case, the output from the CCD is signal-processed, specifically, the RGB components are cut off to obtain a monochrome image.
In the surveillance camera, in consideration of such CCD characteristics, when the CCD output level is large (the amount of light is large during the daytime), an infrared cut filter is inserted between the lens and the CCD to output a color signal. A color / monochrome switching camera that automatically inserts a dummy glass piece instead of an infrared cut filter to output a black and white signal when the output level is low (low light quantity such as at night) has been proposed (for example, Patent Documents). 1).

FIG. 6 is a block diagram showing the overall configuration of a conventional color / monochrome switching camera. In the camera cabinet (2), the lens (1), the CCD (4), and an infrared cut filter (7) that is selectively inserted into a space K between the lens (1) and the CCD (4). ) Or dummy glass piece (5), a slide mechanism (20) driven by the motor (M) to move the infrared cut filter (7) and the dummy glass piece (5) in the direction of arrow A in FIG. 6, and a signal processing circuit (30), a changeover switch (SW) for outputting a color signal or a monochrome signal, a detection circuit (31), a state sensor (21), and a control means (3) are provided.
The infrared cut filter (7) and the dummy glass piece (5) are connected to each other in a plane orthogonal to the lens optical axis L and arranged side by side. Either the infrared cut filter (7) or the dummy glass piece (5) is inserted into the space K, and the other is removed from the space K.
Of the light incident through the lens (1), the wavelength component in the infrared region (about 700 nm or more) is removed by the infrared cut filter (7). The CCD (4) converts light incident through the infrared cut filter (7) or the dummy glass piece (5) into an electrical signal. The signal processing circuit (30) receives the electrical signal from the CCD (4) and generates a color signal Cout and a monochrome signal (luminance signal) Yout. The detection circuit (31) integrates the value of the black and white signal Yout generated by the signal processing circuit (30) and outputs the integrated value Vout.

The state sensor (21) outputs an L (low) level state signal S when the infrared cut filter (7) is inserted into the space K, and a dummy glass piece (5) is inserted into the space K. In this case, the H (high) level state signal S is output.
When the vertical synchronizing signal Vd is input from the signal processing circuit (30), the control means (3) takes in the state signal S from the state sensor (21) and the integrated value Vout from the detection circuit (31). A preset threshold value V0 is compared with the integral value Vout. The control means (3) controls the filter switching signal FC and the monochrome / color switching signal YC at the H level when the integral value Vout is equal to or greater than the threshold value V0 and at the L level when the integral value Vout is smaller than the threshold value V0. Is output.

When Vout ≧ V0 In this case , the periphery of the subject is brighter than or equal to the threshold, and the output signal from the camera needs to be the color signal Cout. If the status signal S is at the L level, the infrared cut filter (7) is inserted in the space K, and is left as it is.
If the status signal S is H level, since the dummy glass piece (5) is inserted in the space K, the control means (3) outputs an H level filter switching signal FC to the motor (M). The motor (M) drives the slide mechanism (20), removes the dummy glass piece (5) from the space K, and inserts the infrared cut filter (7).
When Vout <V0 In this case , the periphery of the subject is darker than the threshold value, and the output signal from the camera needs to be a monochrome signal Yout. If the status signal S is at the H level, the dummy glass piece (5) is inserted in the space K, and is left as it is.
If the status signal S is at the L level, the infrared cut filter (7) is inserted into the space K, so that the control means (3) outputs an L level filter switching signal FC to the motor (M). The motor (M) drives the slide mechanism (20), removes the infrared cut filter (7) from the space K, and inserts the dummy glass piece (5).

When the change-over switch (SW) receives an H-level monochrome / color switching signal YC, it outputs the color signal Cout generated by the signal processing circuit (30) from the output terminal (22) of the camera. When the monochrome / color switching signal YC is received, the monochrome signal Yout generated by the signal processing circuit (30) is output from the output terminal (22) of the camera.
However, in the configuration of FIG. 6, if the integrated value Vout is slightly smaller than the threshold value V0, the dummy glass piece (5) is inserted into the space K, and thus the light that has been removed by the infrared cut filter (7). Is input to the CCD (4). As a result, the control means (3) erroneously senses that the area around the subject has become bright, and this time, the dummy glass piece (5) is removed and the infrared cut filter (7) is inserted. That is, dummy glass pieces (5) and infrared cut filters (7) are inserted alternately, and this is called a hunting phenomenon.

As a countermeasure, there is one provided with a hysteresis characteristic. As shown in FIG. 7, two threshold values V1 and V2 are provided. V1 is sufficiently dark and V2 corresponds to a sufficiently bright luminance level. Even when the surroundings of the subject become dark during color output, switching to monochrome output is not performed until the integrated value Vout becomes equal to or less than the threshold value V1. Even if the surroundings of the subject become bright during the monochrome output, the color output is not switched until the integrated value Vout becomes equal to or higher than the threshold value V2. That is, when the surroundings of the subject are sufficiently dark, switching to black and white output is performed, and when the surroundings of the subject is sufficiently bright, switching to color output is performed to prevent the hunting phenomenon.
As a measure for preventing the hunting phenomenon, as shown in FIG. 8, an infrared cut filter (7) is attached to the peripheral portion of the CCD (4), and the luminance level of the video signal that has passed through the infrared cut filter (7) is determined. Some determine whether to switch between color output and monochrome output. The hunting phenomenon does not occur because the video signal passes through the infrared cut filter (7) even when outputting black and white (for example, see Patent Document 2).
In place of the above configuration, as shown in FIG. 9, a light sensor (8) is separately provided outside the cabinet (2), and color output and monochrome output are switched based on the output of the light sensor (8). is there.

JP 11-239356 A JP 2002-135788 A

As shown in FIG. 7, in the configuration in which the hysteresis characteristic is provided and the color output and the black and white output are switched, the color output may be performed even when the periphery of the subject is dark, and the switching between the color / monochrome output is slow. And give an impression. Also, if the subject is under infrared illumination, the infrared cut filter (7) removes the infrared rays, so that there is a possibility that a black and white signal may be output despite the surroundings of the subject being bright.
In the configuration using the CCD (4) shown in FIG. 8, it takes time to attach the infrared cut filter (7) to the periphery of the CCD (4) at a precise position, resulting in an increase in cost. In addition, when the periphery of the subject is dark, the amount of light transmitted by the infrared cut filter (7) is reduced, so that an image with a peripheral edge cut is displayed. In other words, there is a problem that the image is large when the periphery of the subject is bright and the image is small when the periphery of the subject is dark.
In the configuration in which color output and monochrome output are switched based on the output of the optical sensor (8) as shown in FIG. 9, the brightness of the subject and the ambient brightness of the optical sensor (8) may not match. There is a risk of making a determination.
The object of the present invention is to solve the above problems.

  An optical sensor (8) that senses the light that has passed through the lens (1) is provided at the periphery of the light receiving surface (40) of the solid-state imaging device, and the control means (3) outputs to the optical sensor (8). Based on this, the arrangement of the infrared cut filter (7) or the translucent member in the space K is switched. The optical sensor (8) reacts only to visible light out of the light passing through the lens (1).

In the configuration of the present invention, since the color / monochrome output is switched using the light collected by the lens (1), the brightness of the subject and the brightness around the optical sensor (8) do not match. It is possible to eliminate misjudgment due to.
In addition, color output and monochrome output are switched based on only visible light out of light from the subject. Even if the infrared cut filter (7) is inserted in the space K, visible light passes through the infrared cut filter (7), so there is no possibility of erroneously detecting the brightness of the subject. Therefore, even if the hysteresis characteristic is not provided, the hunting phenomenon can be prevented and the impression that the color / monochrome output switching is not made is not given.
Furthermore, even when the subject is under infrared illumination, color output and black-and-white output are switched based on only visible light, so that there is no possibility that black-and-white output will be erroneously performed even though the subject is bright.

(First embodiment)
Hereinafter, an example of the present invention will be described with reference to the drawings.
FIG. 1 is an internal block diagram of the camera device according to the present example, and FIG. 2 is a front view of the CCD (4), which is the solid-state imaging device of FIG. 1, as viewed from the lens (1) side. This example is characterized in that an optical sensor (8) that reacts only to visible light out of the light that has passed through the lens (1) is provided at the periphery of the CCD (4). The operations of (30), the detection circuit (31), and the slide mechanism (20) are the same as in the prior art. Visible light is light having a wavelength (400 to 700 nm) between infrared rays and ultraviolet rays, and passes through both the infrared cut filter (7) and the dummy glass piece (5).
A light receiving surface (40) having a substantially rectangular shape is provided in the CCD (4), and photographed image information is detected by the light receiving surface (40). Since the lens (1) is circular, the irradiated portion (10) where the light from the lens (1) illuminates the CCD (4) is circular, and the light receiving surface (40) is included in the irradiated portion (10). . A plurality of optical sensors (8) and (8) are provided in the periphery of the light receiving surface (40) in the irradiated portion (10), and four in the vertical and horizontal directions in FIG. 2, but the number is not limited to this. The outputs of the optical sensors (8) and (8) are input to the control means (3). The optical sensor (8) outputs a signal indicating whether the received light is above a certain luminance level.

  In addition, in order to detect light reliably, the optical sensors (8) and (8) are provided in the portion (10a) (see FIG. 2) in which the area of the periphery of the light receiving surface (40) is large in the irradiated portion (10). It is good to be done. Further, if the lens (1) is replaced with one having a large effective image circle and the area of the irradiated portion (10) is increased, the optical sensors (8) and (8) can be easily attached.

When the subject is bright , visible light passes through the space K regardless of which of the infrared cut filter (7) and the dummy glass piece (5) is inserted. That is, visible light is not affected by the infrared cut filter (7).
When the subject is bright, the luminance level of visible light detected by the optical sensor (8) is above a certain level. The optical sensor (8) outputs a signal to that effect to the control means (3), and the control means (3) drives the motor (M) and inserts an infrared cut filter (7) in the space K so that the color image is displayed. Remove redness from the signal.
When the subject is dark and the subject is dark, the luminance level of visible light detected by the optical sensor (8) is less than a certain level. The optical sensor (8) outputs a signal to that effect to the control means (3), and the control means (3) drives the motor (M) to insert the dummy glass piece (5) into the space K. A monochrome signal Yout generated by the signal processing circuit (30) is output from the output terminal (22) of the camera.

In the above example, a plurality of optical sensors (8) and (8) are provided in the periphery of the light receiving surface (40) in the irradiated portion (10). This is because the brightness levels sensed by all the light sensors (8) and (8) are not necessarily the same. Therefore, a plurality of light sensors (8) and (8) are provided, and color / monochrome signals are obtained from the plurality of information. Is switched.
For example, it is assumed that the image of the subject is an image in which the lower end portion is dark and the other portions are bright as shown in FIG. In this case, the lowermost optical sensor (8a) shown in FIG. 2 outputs a signal indicating that the subject image is dark, and the other three optical sensors (8), (8), and (8) indicate that the subject image is bright. Output a signal. Since the image of FIG. 3 is generally bright, a color image should be output. The control means (3) determines that the subject image is generally bright from the outputs of the four optical sensors (8), (8), (8), and (8a), and outputs a color image from the signal processing circuit (30). . If the brightness of the subject image can be captured as a whole, instead of providing a plurality of photosensors (8) and (8), the peripheral portion of the light receiving surface (40) in the irradiated portion (10) One photosensor having the same shape may be provided.

(Second embodiment)
FIG. 4 is a plan view of the CCD (4) according to this example, and FIG. 5 is a front view of the CCD (4) of FIG. 4 as viewed from the lens (1) side. The space K is actually narrow, and it may be difficult to deploy the optical sensor (8) in the space K. In this example, in view of such a case, a light guide means thinner than the optical sensor (8), specifically, a prism (9) is arranged on the periphery of the light receiving surface (40) on the CCD (4). An optical sensor (8) is provided on the light traveling side (that is, outside) with respect to the prism (9).
The light irradiated on the peripheral portion of the light receiving surface (40) is reflected outwardly by 90 degrees from the inclined surface (90) of the prism (9), and enters the optical sensor (8). The point that the color / monochrome signal is switched based on the output of the photosensor (8) is the same as in the first embodiment. The prism (9) is exemplified as the light guiding means for changing the light traveling path, but a reflector or an optical fiber may be used instead.

In the configuration of this example, since the color / monochrome output is switched using the light collected by the lens (1), the brightness of the subject and the brightness around the optical sensor (8) do not match. It is possible to eliminate erroneous determination due to
In addition, color output and monochrome output are switched based on only visible light out of light from the subject. Even if the infrared cut filter (7) is inserted in the space K, visible light passes through the infrared cut filter (7), so there is no possibility of erroneously detecting the brightness of the subject. Therefore, even if the hysteresis characteristic is not provided, the hunting phenomenon can be prevented and the impression that the color / monochrome output switching is not made is not given.
Furthermore, even when the subject is under infrared illumination, color output and black-and-white output are switched based on only visible light, so that there is no possibility that black-and-white output will be erroneously performed even though the subject is bright.

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above-described embodiment, and various modifications can be made within the technical scope described in the claims.

It is an internal block diagram of a camera apparatus. It is the front view which looked at CCD of FIG. 1 from the lens side. It is a figure which shows an example of a to-be-photographed object image. It is a top view of CCD of another Example. It is the front view which looked at CCD of FIG. 4 from the lens side. It is the block diagram which showed the whole structure of the conventional color / monochrome switch camera. It is a figure explaining a hysteresis characteristic. It is a front view of the conventional CCD. It is a perspective view of the conventional cabinet.

Explanation of symbols

(1) Lens
(2) Cabinet
(3) Control means
(4) CCD
(5) Dummy glass piece
(7) Infrared cut filter
(8) Optical sensor
(9) Prism
(40) Photosensitive area

Claims (5)

In the space K between the lens and the solid-state imaging device, an infrared cut filter or a translucent member is selectively provided,
When the light from the subject is brighter than a threshold that is a predetermined luminance level, an infrared cut filter is provided in the space K, and when the light from the subject is darker than the threshold, a translucent member is provided in the space K. In camera equipment provided with a control means for outputting a signal indicating that
An optical sensor that senses the light that has passed through the lens is provided in the periphery of the light receiving surface of the solid-state imaging device, and the control unit is configured to input the infrared cut filter or the translucent member into the space K based on the output of the optical sensor. Camera equipment characterized by switching deployment. The camera device according to claim 1, wherein the optical sensor responds only to visible light among light passing through the lens. 3. The camera according to claim 1, wherein a plurality of optical sensors are provided in a peripheral portion of the light receiving surface, and the arrangement of the infrared cut filter or the translucent member in the space K is switched based on outputs from the plurality of optical sensors. machine. Between the infrared cut filter or translucent member and the solid-state image sensor, a light guide means for changing a traveling path of light incident on the peripheral portion of the solid-state image sensor is provided. The camera device according to claim 1, wherein the camera device is disposed on a traveling side. The camera device according to claim 4, wherein the light guide means is any one of a prism, a reflector, and an optical fiber.

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