JPH06121213A - Cctv camera - Google Patents

Abstract

PURPOSE:To eliminate deficient sensitivity by focusing an image based on a visible light and an image based on infrared rays by separate optical systems and forming each image so as to make the images coincide with one face. CONSTITUTION:A visible light is fed to an infrared-ray filter 1 in a 1st optical system, the focus of a 1st lens 2 is implemented to form the image of a visual light onto the image forming face of a CCD 9. An infrared-ray 12 is fed to a visual light filter 5 in a 2nd optical system, the focus the 2nd lens 6 is regulated to form the image of infrared rays onto the image forming face of the CCD 9. Since the spectroscopic sensitivity characteristic of the CCD 9 has the sensitivity in a visual light area and an infrared-ray area 12, the optical energy of both images is converted into an electric signal by photoelectric conversion. Furthermore, even when the ratio of the components of the visible light and the infrared rays of a light source at night is subjected to change, since the visual light and the infrared rays in 1st and 2nd optical system are focused separately, no defocusing is caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CCTV camera capable of preventing a focus shift due to a change in color temperature of a light source during the daytime and nighttime.

[0002]

CCTV cameras are often used, for example, to monitor ATMs in banks. In that case, is it used to monitor a bank automatic payment machine installed in a small room partitioned by glass etc. so that the inside can be seen from the outside for crime prevention with a CCTV camera fixed near the ceiling of the room? I am playing. Therefore, the light source of the camera has a large change in light component between day and night. In a conventional CCTV camera, as shown in FIG. 2, 20 is a lens for forming an image of a subject on an image sensor 22, and 21 is the lens 20.
Is a focus adjusting mechanism that moves the lens back and forth to focus so that the image plane is located at an appropriate position, 22 is an image sensor such as a CCD, and 24 is an infrared filter. . Generally, when installing a camera, the lens 20
The focus is adjusted by moving the to and fro, and the focus is adjusted so that a clear image can be obtained. In addition, once the focus is adjusted, it is normal to use it as it is. Therefore, the infrared filter 24 is attached to the outside of the lens 20, and the light 25 from the subject is reflected by the infrared filter 2.
By passing through 4, almost only the visible light component 26 reaches the lens 20, and only the visible light component 26 is focused. The reason is that the proportion of the components of the light source (infrared and visible light) changes between daytime and evening and night. Moreover, for example, the spectral sensitivity characteristics of a CCD used as an image sensor also senses an infrared component. Therefore, focusing with a light source in the daytime (the ratio of visible light is large), the ratio of the infrared component is in the evening and at night. The image is affected by an increase in the focus, resulting in an out-of-focus image (because the focal length of the optical lens varies depending on the wavelength). On the other hand, in order to avoid the out-of-focus, the conventional method of removing the infrared component by the infrared filter 24 and using only visible light can avoid out-of-focus, but causes a problem of insufficient sensitivity of the CCD.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, in which an image based on visible light and an image based on infrared light are focused by different optical systems, and each image is recorded as 1. An object of the present invention is to provide a CCTV camera in which the optical system is provided so as to form an image by matching with one surface, and the image formation is photoelectrically converted by an image sensor.

[0004]

In order to achieve the above object, an infrared filter that transmits light in the visible light region and blocks infrared rays and the light that has passed through the infrared filter is imaged at a predetermined position. The first lens having a focus adjustment function and the image forming light of the first lens are transmitted, and the image forming light output from the second optical system is totally reflected in the direction of the image forming light of the first lens. A first optical system consisting of a first prism or a half mirror, a visible light filter for transmitting light in the infrared region and blocking light in the visible light region, and light passing through the visible light filter for the first light A second lens having a focus adjusting function so as to form an image on the image forming surface of one optical system, and a direction in which the image forming light of the second lens is made to coincide with the image forming surface of the first optical system. With a second prism or mirror that totally reflects The second optical system consisting of, and an optical signal having sensitivity to light in the visible light region and infrared rays, which is installed on the image plane obtained by overlapping the first optical system and the second optical system, is converted into an electrical signal. It consists of an image sensor for conversion.

[0005]

With the above construction, the first optical system supplies image formation based on visible light to the image pickup device, and the second optical system supplies image formation based on infrared light to the image pickup device. ,
The visible light and infrared rays, which are the components of the light source, are all used for image formation, and the image of the object formed of light and infrared rays in the visible light region is formed at a predetermined position of the image sensor, and the light energy of the image formation is , Efficiently converted into electric signals.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A CCTV camera according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a CC according to the present invention.
It is a principal part block diagram of a TV camera. Reference numeral 1 denotes an infrared filter that passes only the light 11 in the visible light region of the light 10 from the subject and blocks infrared rays. Reference numeral 2 is a first lens having a focus adjusting function for focusing the light passing through the infrared filter 1 at a predetermined position. Reference numeral 3 is a first prism that transmits the image forming light of the first lens 2 and totally reflects the image forming light output from the second optical system in the direction of the image forming light of the first lens 2. is there. The above-mentioned components form a first optical system. Reference numeral 5 denotes a visible light filter that allows light 12 in the infrared region to pass while blocking light 11 in the visible light region. 6 denotes the light passing through the visible light filter 5,
It is a second lens having a focus adjusting function for forming an image so as to match the image forming surface of the first optical system. Reference numeral 7 is a second prism that totally reflects the image forming light of the second lens 6 in a direction in which the image forming surface of the first optical system is made to coincide with the image forming surface. A second optical system is formed by each of the above parts. Reference numeral 9 denotes an image pickup device such as a CCD which is installed on an image forming plane obtained by overlapping the first optical system and the second optical system and which converts an optical signal into an electric signal.

The operation will be described. The first optical system is supplied with visible light by the infrared filter 1, and adjusts the focus of the first lens to form a visible light image on the image forming surface of the CCD. Further, the second optical system is supplied with infrared rays by the visible light filter 5 and adjusts the focus of the second lens 6 to form an infrared image on the image plane of the CCD. C
As shown in FIG. 2, the spectral sensitivity characteristic 30 of the CD also has sensitivity in the visible light region 31 and the infrared region 32.
Photoelectric energy of both images can be converted into an electric signal by photoelectric conversion. Also, even if the ratio of visible light and infrared light components of the light source changes at night, image formation is focused separately for visible light and infrared light by the first optical system and the second optical system. Does not happen.
The infrared filter 1 and the visible light filter 5 may be provided immediately before the first prism 3 and the second prism 7, respectively. Further, the first prism 3 may be a half mirror and the second prism 7 may be a mirror. Further, in order to prevent out-of-focus, it is possible to provide a sensor and stop the image formation in the optical system that processes a small component based on the component of the external light detected by the sensor.

[0008]

As described above, according to the present invention, an image based on visible light and an image based on infrared light are focused by different optical systems, and each image is formed so as to coincide with one surface. A CCT, which comprises the first and second optical systems described above, and photoelectrically converts the image formation by an image sensor.
Provide a V camera. Therefore, in various surveillance cameras used in an environment where the light component from the subject changes due to the influence of external light, the focus adjusted by the light source in the daytime can be prevented from becoming out of focus in the evening and night. At the same time, the shortage of sensitivity, which is a drawback of the conventional method of using only visible light in order to avoid out-of-focus, is also solved.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a CCTV camera according to the present invention.

FIG. 2 is a block diagram of a main part of a conventional CCTV camera.

[Explanation of symbols]

 1 Infrared Filter 2 First Lens 3 First Prism 5 Visible Light Filter 6 Second Lens 7 Second Prism 9 CCD 10 Light from Subject 11 Light in Visible Light Region 12 Light in Infrared Region 20 Lens 21 Focus adjustment mechanism 22 Image sensor 24 Infrared filter 25 Light from subject 26 Visible light component

Claims (3)

[Claims] 1. An infrared filter which transmits light in the visible light region and blocks infrared rays, and a first lens having a focus adjustment function for focusing the light passing through the infrared filter at a predetermined position, and A first prism or a half mirror that transmits the image forming light of the first lens and totally reflects the image forming light output from the second optical system in the direction of the image forming light of the first lens. One optical system, a visible light filter that transmits light in the infrared region and blocks light in the visible light region, and the light that has passed through the visible light filter is imaged on the image formation surface of the first optical system. As described above, the second lens having the focus adjusting function and the second prism or the mirror for totally reflecting the image forming light of the second lens in the direction to match the image forming surface of the first optical system A second optical system, and the first optical system and Beauty second installed in imaging plane obtained so as to overlap from the optical system CCTV camera, comprising the image pickup element for converting an optical signal having a sensitivity to light and infrared in the visible light region to an electric signal. 2. A sensor for detecting color temperature of a light source is provided,
2. The CCTV camera according to claim 1, wherein the first optical system or the second optical system is switched based on the detection result of the sensor to supply the image formation of one of the optical systems to the image element. 3. The CCTV camera according to claim 1, further comprising a focus adjustment function for focusing the image of the second optical system so as to match the image of the first optical system.