KR101036172B1 - Closed circuit television camera with focus adjusting mode - Google Patents

Abstract

PURPOSE: A closed circuit camera equipped with a focus control setting mode is provided to photograph a clear image regardless of focus control of a camera installer or the brightness variation of a camera installation place. CONSTITUTION: A control unit(150) controls a focusing control setting mode. The control unit controls an aperture level of an iris through the control of an iris driver in a focusing control setting mode. The control unit controls the brightness of an image through the control of exposure time of an image sensor. The control unit photographs a subject in order to control the focus of lens by the depth of field.

Description

CLOSED CIRCUIT TELEVISION CAMERA WITH FOCUS ADJUSTING MODE}

The present invention relates to a closed-circuit camera having a focus adjustment setting mode, and more particularly, to provide a focus adjustment setting mode for precisely focusing so that a subject can always be clearly captured regardless of ambient brightness. A closed circuit camera.

Apparatus for acquiring video signal of CCTV (Closed Circuit Television) surveillance system is attached to CCTV camera (closed circuit camera) with CCD or CMOS image sensor, so that image is imaged on the image sensor. It is composed of a lens, the focus of the lens (Focus) must fit the image sensor accurately to obtain a clear image.

On the other hand, the field installation of CCTV cameras is mainly performed during the day, and the brightness of the surroundings is high during the day, so that the amount of light incident to the CCTV camera is sufficient, so that the subject may appear too bright in the captured image. The focus is adjusted for a subject placed at a specific distance in the state. When the diaphragm is tightened in this way, the depth of field (or depth of focus) becomes deep due to the pinhole effect caused by the diaphragm. When the depth of the subject becomes deeper, the distance range for obtaining a clear image of the subject becomes wider. .

In this case, when the aperture is focused while the aperture is reduced during the day, the subject depth becomes shallow when the aperture is opened due to dark surroundings such as at night, and the subject depth becomes shallow during the day. This can lead to out-of-focus distances.

In addition, in a closed circuit camera having an infrared cut filter, when the infrared cut filter is inserted and removed as the amount of ambient light changes as it enters from night to day or from day to night, the medium between the lens and the image sensor changes. As a result, the focal length may change.

In addition, in a closed circuit camera that provides a DSS function, there is a problem that it is difficult to focus due to a screen drag phenomenon or a phenomenon in which the movement of a subject in an image is intermittently displayed when the DSS function is driven.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and even if the depth of the subject caused by the opening amount of the aperture linked to the brightness of the place where the closed-circuit camera is installed is changed, the subject is placed at a specific distance when the camera is installed. It is an object of the present invention to provide a focusing setting mode that allows the camera to focus accurately.

Another object of the present invention is to provide a focus adjustment setting mode for inserting and removing an infrared cut filter in a closed circuit camera having an infrared cut filter so as to optimally focus even if the focal length is changed.

In addition, the present invention provides a closed-circuit camera that provides a DSS function, which can solve the problem of difficulty in focusing due to a screen drag phenomenon or a phenomenon in which the movement of a subject in an image is displayed when the DSS function is driven. It is an object to provide a focus adjustment setting mode.

The present invention for achieving the above object is a lens system for refracting incident light including a subject, a focus adjuster for adjusting the focus of the lens system by a user's manual operation, and the amount of opening to adjust the amount of light refracted incident light; A changeable aperture, an aperture driver for adjusting the opening amount of the aperture, and an incident light disposed at a focal position of the lens system and adjusted by the aperture through the lens system for a predetermined exposure time to output an optical signal. And an image sensor to generate image information for expressing an image of the subject by receiving the optical signal with respect to the subject while the focal point of the lens system is fixed at a specific position. Camera control to control the aperture driver to adjust the opening amount of the aperture accordingly A closed circuit camera comprising: a focus adjustment setting mode for adjusting a focus of the lens system by adjusting the focus adjuster while a user confirms the photographed image displayed on a predetermined display means. In the focus adjustment setting mode, the aperture driver is controlled to maximize the amount of opening of the aperture, and the exposure time of the image sensor is controlled to adjust the brightness of the captured image, thereby opening the aperture. Provided is a closed circuit camera having a focus adjustment setting mode, characterized in that the subject can be clearly photographed by preventing the focus from being incorrectly adjusted due to the change in the depth of the subject due to the amount.

The camera controller may release the DSS function of increasing the photosensitive time of the image sensor by twice the standard photosensitive time as the brightness of the captured image becomes dark.

The closed circuit camera may further include an infrared cut filter for blocking infrared rays from incident light and a filter driver for inserting or removing the infrared cut filter with respect to the incident light, and in the focus adjustment setting mode, the camera controller may be configured in advance. And controlling the filter driver to perform an operation of inserting or removing the infrared cut filter with respect to the incident light at a predetermined predetermined time period.

According to the closed-circuit camera according to the present invention having the above-described configuration, regardless of the brightness change of the installation location of the camera or regardless of the focusing skill of the camera installer, it is possible to always capture an optimal clear image.

In addition, by properly applying or releasing various functions applied to a closed circuit camera, such as an auto iris function, a digital slow shutter function, an insertion and removal function of an infrared cut filter, an electronic shutter function, and the like, the focus of the lens can be accurately adjusted. To help.

1 is a diagram schematically showing a configuration of a closed circuit camera according to the present invention.
2 is a diagram for explaining a subject depth in the present invention.
3 is a flowchart illustrating a focus adjustment setting method according to the present invention.

Hereinafter, the configuration and operation of the focus adjustment setting mode of the closed circuit camera according to the present invention will be described with reference to the accompanying drawings.

1 is a diagram schematically showing a configuration of a closed circuit camera according to the present invention. The closed circuit camera consists of a lens part 101 and a camera body 102. In addition, the lens unit 101 may include a lens system 110, a focus adjuster 112, an aperture 120, an aperture driver 122, a filter unit 130, and a filter driver 132. Can be. In addition, the camera body 102 further includes an image sensor 140 and a camera controller 150. Here, although the filter unit 130 and the filter driver 132 are described as being included in the lens unit 101, these components may be selectively disposed on the camera body 102, or may not be optionally provided. It may not.

The lens unit 101 may be coupled to the camera body 102 by a thread structure or the like. The lens unit 101 includes a lens system 110 having at least one lens element. Although the figure shows a lens system in the form of only one lens element, it can be understood that it is equivalent to a plurality of lens elements.

On the other hand, in the lens system 110 included in the lens unit 101, a focus adjuster for changing the focal length (or the position at which the image is formed) of the lens system 110 by advancing or retracting one or a plurality of lens elements in the optical axis direction ( 112 is disposed, the focus adjuster 112 includes a handle and the like that can be operated by the user from the outside. The structure having the focus adjuster 112 enables the user to accurately adjust the focus of the lens of the closed circuit camera.

The aperture 120 may automatically adjust the amount of opening to adjust the amount of incident light including the subject A. FIG.

The aperture driver 122 adjusts the opening amount of the aperture 120 according to the aperture control signal input.

As the opening amount of the diaphragm 120 is adjusted by the operation of the aperture driver 122 as described above, when the surroundings are bright, such as in the daytime, the opening amount of the diaphragm 120 is reduced to reduce the amount of incident light and to reduce the amount of incident light. In this case, the opening amount of the aperture 120 is increased to increase the amount of incident light so that a bright image can be taken.

The filter unit 130 includes an infrared cut filter 135 inserted in a direction perpendicular to the optical axis of the incident light reaching the image sensor 140 to block infrared rays included in the incident light.

The filter driver 132 inserts or removes the infrared cut filter 135 of the filter unit 130 in a direction perpendicular to the optical axis of the incident light by an input filter control signal.

That is, when the surroundings are bright, such as during the day, the infrared cut filter 135 is inserted to prevent the light of the infrared wavelength band from entering the image sensor 140. When the surroundings are dark, such as at night, the infrared cut filter 135 is inserted. The infrared rays may be incident on the image sensor 140 by removing the infrared rays. This means that the amount of incident light is sufficient during the day so that the infrared light can be cut off to obtain an image that clearly expresses the natural color of visible light visible to the human eye. We want to get rid of color and get the brightest possible image.

In addition, the filter unit 130 may further include a dummy filter 136 made of a material having the same refractive index as that of the infrared cut filter 135 and transmitting all light including infrared light as well as visible light. The dummy filter 136 may change the focal length of the lens according to the change of the medium when the infrared cut filter 135 for blocking the infrared light is removed, so that the dummy filter 136 may be replaced with the optical axis of the incident light instead of the infrared cut filter 135. By being inserted, the characteristics of the medium interposed on the optical axis from the lens system 110 to the image sensor 140 are always the same.

On the other hand, the configuration order as described above consisting of the lens system-aperture-filter unit-image sensor may be arbitrarily changed according to design, and one or a plurality of configurations may be removed as necessary.

The camera controller 150 receives an optical signal by controlling an operation of the image sensor 140 that detects incident light for a predetermined exposure time and outputs an optical signal, and generates a photographed image using the received optical signal, The generated image is converted and output as digital or analog image information so as to be visually displayed by a separate display means which can be connected to the outside.

For example, if the external display means operates in the NTSC method or the PAL method, the camera controller 150 outputs image information of one captured image every 1/60 second or 1/50 second.

Further, the camera controller 150 analyzes the overall brightness of the photographed image or the brightness of the subject A among the photographed images, and adjusts the aperture control signal to adjust the amount of incident light to appropriately adjust the brightness of the image. Create and print In addition, when the filter unit 130 is additionally provided, the filter control signal may be output.

The camera body 102 is a housing for accommodating each component of the closed circuit camera, and fixing means (not shown) may be formed to fix the closed circuit camera to a wall surface of an installation site or the like. In addition, the camera body 102 may be provided with an operation means including a user operation button (not shown) for starting the focus adjustment setting mode according to the present invention, and separate image information on the captured image. Data output means (not shown) for outputting to the display means may be arranged.

Meanwhile, the distance range of the position of the subject at which the image B appears by the lens is referred to as the depth of the subject, which may vary according to the amount of opening of the aperture 120 disposed between the lens and the image sensor 140. have.

That is, when the opening amount of the aperture 120 is small, the depth of the subject becomes deep (the range of the focus depth is large) due to the pinhole effect of the aperture 120, and when the opening amount of the aperture 120 is large, the subject depth is shallow. (The range of the depth of focus is small).

This principle can be understood with reference to FIG. In FIG. 2, the points at a distance from the closed-circuit camera are represented by d (-), n (-), n (+) and d (+) in order of distance from the close point, and the subject A is n ( It is shown to be located between-) and n (+).

When the aperture 120 of the closed-circuit camera is small, the depth of the subject becomes deep from d (-) to d (+), so that the focus is visible even when the subject A is located in the same section. When the amount of openings is large, the depth of the subject becomes shallow from n (−) to n (+), so that the subject becomes focused only when the subject A is located within a short section within the same section.

Therefore, when the amount of incident light is sufficient during the day and the opening amount of the aperture 120 is automatically reduced, the depth of the subject appears deeply, so that a clear image even when the subject A is in the range from d (-) to d (+). In the state where the aperture 120 is opened due to the insufficient amount of incident light, the depth of the subject is shallow so that the subject A can be clearly photographed only when the subject A is between n (-) and n (+). Will be.

According to this principle, when the lens system 110 is focused to have a subject depth between n (−) and n (+), it is possible to capture a clear image at both day and night.

However, since the closed-circuit camera is generally installed during the day, the lens system 110 is often focused in a state where the amount of incident light is sufficient, and in this state, since the opening amount of the aperture 120 is reduced. The subject depth is deep. Therefore, when focusing in this state, the focus position of the subject A may be adjusted to be between d (−) and n (−) or between d (+) and n (+). By the way, if the focus is made in this way, a clear image of the subject A can be obtained during the day, but at night, the subject A is out of depth of the subject between n (-) and n (+). The image of the subject A is not clear.

Accordingly, the present invention is to solve this problem, in order to adjust the focus of the lens system 110 to the subject depth is between n (-) to n (+), the following focus adjustment setting mode is provided. do.

The focus adjustment setting mode is one of control menus in which a closed circuit camera is fixedly installed at a desired position and then operated by operating a camera operating means.

Operation of the focus adjustment setting mode will be described with reference to FIG. 3.

First, when the focus adjustment setting mode is activated by a user's operation (S100), the camera controller 150 controls the aperture driver 122 to maximize the amount of opening of the aperture 120 (S110). In this case, since the amount of light incident through the aperture 120 is excessive, the image by the optical signal detected by the image sensor 140 is displayed very brightly. That is, since the maximum incident light is received through the diaphragm 120, the image may be displayed so brightly that the subject A may not be identified at all. In this state, since the user cannot focus on the subject A accurately, the camera controller 150 must control the brightness of the captured image.

To this end, the camera controller 150 measures the brightness of the subject A in the entire photographed image or the photographed image. When the measured brightness is equal to or greater than a predetermined reference brightness, the camera controller 150 activates the electronic shutter function. Control of reducing the brightness of the image by reducing the photosensitive time of the photosensitive element constituting 140 (S120).

The electronic shutter function is a function of controlling the photosensitive time of the image sensor 140 according to the amount of incident light passing through the lens system 110. The image shutter 140 allows the image sensor 140 to reduce incident light for a set photosensitive time, When this is done, the optical signal is outputted as a result of the photosensitive result. In the focus adjustment setting mode, since the excessive amount of light is incident by the maximum aperture 120, the electronic shutter function is necessary to adjust the brightness of the captured image.

On the other hand, the camera controller 150 releases the DSS function (S130).

The DSS function is as described in Korean Patent Application No. 20-221646 (name: board-type camera having ultra low light sensitivity characteristic) filed and registered by the same applicant as the present invention. That is, in general, when the illuminance of the subject photographed by the camera becomes dark and the amount of light incident on the image sensor 140 becomes less than a predetermined amount, the photosensitive time by the electronic shutter function of the image sensor 140 is the longest time in the basic state. 1/60 sec (1/60 sec for NTSC, 1/50 sec for PAL) and increase the amplification gain of the optical signal. In this situation, when the brightness of the image becomes darker, the image sensor 140 is exposed to incident light for a longer time than 1/60 second (for example, even multiples of 1/60 second) by activating the DSS function. It accumulates and outputs the optical signal.

However, the longer the photosensitivity time in the image sensor 140 is caused by the DSS function, the dragged phenomenon occurs in the movement of the subject A in the captured image, and thus the number of still images displayed per second is less. As a result, the movement is interrupted and is shown. Therefore, when the DSS function is operated, when the focus of the lens system 110 is adjusted, the movement of the subject A is delayed and not displayed in real time, thereby making it difficult to accurately adjust the focus. For this reason, it is preferable to disable the DSS function in the focus adjustment setting mode.

In addition, the camera controller 150 repeats the operation of forcibly inserting or removing the infrared cut filter 135 into the optical axis of the incident light by outputting the filter control signal to the filter driver 132 (S140).

That is, the camera controller 150 inserts the filter unit 130 (that is, the infrared cut filter) at a randomly set time period (for example, 1 second or 5 seconds) in the focus adjustment setting mode. Alternatively, the removing operation may be repeated. As a result, the user can focus the lens system 110 while checking the case where the filter unit 130 is inserted and the case where the filter unit 130 is removed.

This function is particularly useful in closed circuit cameras not equipped with a dummy filter 136, which has a predetermined thickness in the path of incident light from the lens system 110 to the image sensor 140 (i.e., the infrared cut filter of the filter portion). ) Is to reproduce the situation in which the focal length changes as the () is inserted or removed so that the best focus can be achieved.

Of course, such control can be applied to the case where the infrared cut filter 135 and the dummy filter 136 are provided at the same time. That is, by interposing the infrared cut filter 135 and the dummy filter 136 alternately according to a predetermined time period, the optimal focus adjustment is possible.

As described above, the technology for controlling the filter unit 130 and processing the photographed image is Korean Registered Application No. 20-323585 (name: black and white color combined charge using a removable infrared cut filter) filed and registered by the same applicant as the present application. Control system for imaging of the combined element camera).

By generating and outputting image information based on the optical signal output from the image sensor 140 while performing the above-described processes, the image captured by the external display means connected to the closed circuit camera can be visually displayed. In operation S150, the user adjusts the focus adjuster 112 while adjusting the focus of the lens system 110 while viewing the displayed image in operation S150. When the focus adjustment is completed, the user terminates the focus adjustment setting mode by using the operation means, so that the camera controller 150 of the closed circuit camera can operate the operation mode before executing the focus adjustment setting mode (for example, the normal operation mode). Return to (S170).

According to the focus adjustment setting mode as described above, since the lens is focused in a state where the aperture 120 is opened at the maximum, the pinhole effect by the aperture 120 can be eliminated as much as possible, and the subject depth is n (-). Can be adjusted to be between n (+).

It is assumed that a closed circuit camera having a focus adjustment setting mode according to the present invention as described above has at least an electronic shutter function. The focus adjustment setting method in the installation of such a closed circuit camera executes the focus adjustment setting mode so as to open the aperture to the maximum while the auto iris function and the DSS function are blocked, And adjusting the brightness and capturing and displaying an image in a state where the filter unit is inserted or removed at predetermined time intervals.

According to such a configuration and operation, when the closed-circuit camera is installed in the field, the lens lens can be adjusted in the state where the subject depth is lowest by fully opening the aperture of the camera lens. You can always get a clear image without being affected by the brightness of the surrounding environment.

In addition, the lens can be quickly focused without being affected by image delay or image interruption caused by the DSS function in a dark place.

In addition, by forcibly inserting or removing the infrared cut filter repeatedly, the focus can be adjusted in consideration of the change in focus depending on whether or not the infrared cut filter is interposed.

101: lens unit
102: camera body
110: lens system
120: aperture
130: filter unit
140: image sensor
150: camera control unit

Claims (3)

A lens system for refracting incident light including a subject, a focus adjuster for adjusting the focus of the lens system by a user's manual operation, an aperture with a variable opening amount to adjust an amount of incident light, and an opening amount of the aperture An aperture driver, an image sensor disposed at a focal position of the lens system and diminishing incident light adjusted by the aperture through the lens system for a predetermined photosensitive time, and outputting an optical signal; and a focal point of the lens system Receiving the optical signal for the subject in the fixed state to generate image information for representing the image taken by the subject and to control the aperture driver in accordance with the brightness of the image to adjust the opening amount of the aperture A closed circuit camera comprising a camera control unit:
The camera controller includes a focus adjustment setting mode for adjusting a focus of the lens system by adjusting the focus adjuster while the user confirms the image displayed on a predetermined display means, and in the focus adjustment setting mode, the aperture By controlling a driver to maximize the amount of opening of the aperture and control the exposure time of the image sensor to adjust the brightness of the image, the focus is incorrectly adjusted due to the change in the depth of the subject by the amount of opening of the aperture And a focus adjustment setting mode, so that the subject can be photographed clearly. The method of claim 1,
The camera controller is configured to cancel the DSS function of increasing the photosensitive time of the image sensor by a factor of two with respect to the standard photosensitive time as the brightness of the image becomes dark. . The method according to claim 1 or 2,
The closed circuit camera,
And an infrared cut filter for blocking infrared rays from the incident light and a filter driver inserting or removing the infrared cut filter with respect to the incident light.
The camera control unit in the focus adjustment setting mode,
And a filter driver to control the filter driver to insert or remove the infrared cut filter with respect to the incident light at a predetermined time period.

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