JP2006148421A - Imaging equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging equipment capable of realizing an automatic focus function by flange back adjustment with a small-sized configuration. <P>SOLUTION: An optical section 16 includes an image pickup device, which is moved by an optical section moving motor 20 in an optical axis direction. A signal processing section 18 controls the optical section moving motor 20 to move the image pickup device within a prescribed focus adjustment moving range so as to match the focus. A lens detection switch 26 detects mount of a lens 14. When the switch 26 detects the mount of the lens 14, the signal processing section 18 moves the optical section 16 to a prescribed adjustment start position within the focus adjustment moving range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus such as a surveillance camera of a lens exchangeable type.

  2. Description of the Related Art Conventionally, there are two types of surveillance cameras as imaging devices: a lens integrated type and a lens exchangeable type. Among these, the surveillance camera of the type in which the lens can be exchanged is assumed to be used in combination with various lenses. For this reason, it is generally not configured to attach an autofocus lens. Therefore, the focus adjustment is generally performed manually. In this case, adjustment on the lens side and adjustment on the camera side are possible.

In the adjustment on the lens side, the lens focus function is used to adjust the position of the lens. On the other hand, in the adjustment on the camera side, the imaging surface is moved and the flange back is adjusted. The flange back is a distance from a lens mounting reference surface to an imaging surface (for example, an imaging surface of a CCD) (see, for example, Patent Document 1). Adjustment of the flange back is also referred to as back focus adjustment.
JP 2001-218091 A (Page 4-5, FIG. 1)

  However, an imaging apparatus such as a surveillance camera may be out of focus after camera installation even if the focus is manually adjusted as described above when the camera is installed.

  For example, when a surveillance camera is installed in the daytime, the depth of field changes with the difference in light quantity between daytime and nighttime. A focus shift may occur with such a change in the depth of field. Further, in a camera capable of infrared imaging, a focus shift may occur when switching between the infrared cut filter and the glass plate. In addition, when infrared illumination is used, the wavelength may change, resulting in out of focus. Furthermore, a focus shift may occur due to the movement of the object to be photographed.

  In this way, when a focus shift occurs after installation, the surveillance camera is often installed in a place that is out of reach, such as a high place, so that it is not easy to perform focus readjustment. Therefore, it is desirable to provide an autofocus function so that manual readjustment of focus is not necessary.

  However, as described above, it is required that a monitor camera capable of exchanging lenses can be attached with various lenses. Considering such requirements, it is not desirable to change the lens side such as providing an autofocus lens. As an alternative, it is conceivable to provide an automatic adjustment function of the flange back and adjust the focus on the camera side. However, in this case, it is required that the subsequent focus shift can be adjusted on the camera side, regardless of the initial focus position on the lens side. It must be taken big. Therefore, simply performing autofocus by flange back adjustment can hinder downsizing of the camera.

  As described above, the conventional imaging apparatus has a problem that when it is intended to realize the autofocus function by adjusting the flange back on the camera side, it is required to make a large adjustment allowance, and therefore, it is difficult to reduce the size. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a small imaging device capable of realizing an autofocus function by flange back adjustment.

  An image pickup apparatus according to the present invention includes an image pickup element, a moving unit that moves the image pickup element in an optical axis direction, and a moving unit that controls the moving unit to move the image pickup element within a predetermined focus adjustment moving range so as to be in focus. An element position control means for detecting, a lens attachment detection means for detecting attachment of the lens, and when the attachment of the lens is detected, the image pickup element is moved to a predetermined adjustment start position within the focus adjustment movement range. Start element position control means. The adjustment start position is preferably at the center of the focus adjustment movement range. However, the adjustment start position does not have to be strictly in the middle of the focus adjustment movement range, and may be in the vicinity of the middle.

  With this configuration, when the lens is mounted, the image sensor moves to the adjustment start position. Therefore, in flange back adjustment for moving the image sensor, the image sensor is within the appropriate focus adjustment movement range before and after the adjustment start position. Therefore, it is only necessary to be movable. Therefore, the moving range of the image sensor can be set small. And since the movement range of an image sensor may be small, size reduction of an imaging device is attained.

  In the imaging apparatus of the present invention, the element position control means controls the element position so as to be focused in response to an external trigger. With this configuration, the focus can be automatically adjusted when an event of defocus occurs.

  In the image pickup apparatus of the present invention, the element position control means controls the element position so as to be in focus in response to switching between the normal photographing mode and the infrared photographing mode. With this configuration, the focus can be automatically adjusted in response to a focus shift at the time of setting the infrared imaging mode. Mode switching is detected, for example, by moving an infrared cut filter. The mode change is detected by turning on / off the infrared illumination.

  In the imaging apparatus of the present invention, the start element position control means moves the imaging element to the adjustment start position in response to removal of the connector of the automatic iris adjuster. With this configuration, the element position can be adjusted when the lens is mounted by using the connector of the automatic iris adjuster.

  The present invention provides an autofocus function based on flange back adjustment by providing start element position control means for moving the image sensor to a predetermined adjustment start position within the focus adjustment movement range when lens attachment is detected. It is possible to provide an imaging apparatus having an effect that it can be realized with a small configuration.

  Hereinafter, an imaging device according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the imaging device is a surveillance camera.

  A surveillance camera according to an embodiment of the present invention is shown in FIG. In FIG. 1, the monitoring camera 10 includes a camera body 12, and a lens 14 is attached to the camera body 12. The lens 14 is replaceable and is a manual focus adjustment type.

  The camera body 12 includes an optical unit 16, a signal processing unit 18, and an optical unit moving motor 20. The optical unit 16 includes an image sensor such as a CCD, and an image of a subject is generated through the lens 14 on the image pickup surface of the image sensor. The subject image is converted into an electrical signal by the optical unit 16.

  The signal processing unit 18 is configured by a computer, processes the image signal supplied from the optical unit 16, and controls the entire camera body 12.

  In addition, an operation instruction signal is input to the signal processing unit 18 from the outside. That is, the monitoring camera 10 is connected to a monitor and a controller. A monitoring video is displayed on the monitor, and an operation instruction signal is sent from the controller to the monitoring camera 10. This operation instruction signal is acquired by the signal processing unit 18, and the signal processing unit 18 controls the monitoring camera 10 according to the operation instruction signal.

  The input of the operation instruction signal serves as an external trigger for operating the monitoring camera 10. The operation instruction signal is, for example, a signal that instructs execution of an autofocus operation described later.

  The optical unit moving motor 20 is controlled by the signal processing unit 18 to move the optical unit 16 in the direction of the optical axis, thereby adjusting the flange back and performing auto focus adjustment.

  The camera body 12 further includes a color / monochrome switching mechanism 22 and a switching motor 24. The color / monochrome switching mechanism 22 performs a switching operation between the color photographing mode and the monochrome photographing mode. The color / monochrome switching mechanism 22 includes a mechanism for switching between an infrared cut filter for a color shooting mode and a dummy glass plate for a monochrome shooting mode.

  The color / monochrome switching mechanism 22 is driven by a switching motor 24. For example, when a color / monochrome switching instruction signal is input from the outside, the signal processing unit 18 controls the switching motor 24 to cause the color / monochrome switching mechanism 22 to perform a switching operation. The signal processing unit 18 may automatically perform switching control when the illuminance falls below a predetermined level. Illuminance is detected by a sensor (not shown), for example.

  The camera body 12 further includes a lens detection switch 26. In the lens detection switch 26, the contact is closed when the lens 14 is attached. Accordingly, the lens detection switch 26 detects the mounting of the lens 14 and sends a lens detection signal indicating the mounting of the lens to the signal processing unit 18.

  In the camera body 12, an ALC (Auto Level Control) connector 28 is connected to the lens-side ALC connector. The ALC connector is a connector for providing an automatic level adjuster function.

  Next, FIG. 2 shows a flange back adjusting mechanism. As shown in FIG. 2, a lens mounting surface 42 is provided on the front surface of the camera housing 40. The optical unit 12 is provided with an image pickup device 44, and an image pickup surface 46 is on the image pickup device 44. The flange back FB is a distance from the lens mounting surface 42 to the imaging surface 46. The image pickup device 44 of the optical unit 12 is moved by the optical unit moving motor 20, whereby the back flange FB is changed and focus adjustment is performed.

  The focus adjustment control function is realized by the signal processing unit 18. That is, the signal processing unit 18 controls the optical unit moving motor 20 to move the image sensor 44 so that it is in focus. The signal processing unit 18 may perform focus adjustment using a known technique. In the present embodiment, the signal processing unit 18 acquires a captured image from the optical unit 12, analyzes the captured image, and obtains a frequency component of the image. Then, the signal processing unit 18 determines whether or not focus is achieved based on the frequency component. If the frequency component is higher than a predetermined level, it is determined that the image is in focus. The signal processing unit 18 repeats the above operation while changing the position of the optical unit 12 little by little, and positions the optical unit 12 to a place where the focus is achieved.

  Next, FIG. 3 shows the position control of the image sensor 44 when the lens is mounted. A focus adjustment movement range A is set on the optical axis L of the camera body 12, and an adjustment start position SP is set at the center of the focus adjustment movement range A. As will be described later, when the signal processing unit 18 detects that the lens 14 is mounted, the signal processing unit 18 moves the image sensor 44 to the adjustment start position SP. More specifically, the imaging surface 46 of the imaging device 44 is positioned at the adjustment start position SP. The adjustment start position SP is a reference for focus adjustment. Thereafter, the image sensor 44 is moved within the focus adjustment moving range A with the adjustment start position SP as a starting point.

  Note that the signal processing unit 18 also controls the optical unit moving motor 24 to move the image sensor 44 to the adjustment start position SP in the control operation at the first power-on. Alternatively, the position adjustment may be performed so that the image pickup element 44 is positioned at the adjustment start position SP at the factory shipment stage. Thereby, even if the surveillance camera 10 is shipped with the lens mounted, the position adjustment of the present embodiment can be realized.

  FIG. 4 shows operations related to autofocus in the monitoring camera 10 of the present embodiment. When the power is turned on (S10), the signal processing unit 18 determines whether or not the lens 14 is already attached based on the input signal from the lens detection switch 26 (S12). If the lens 14 is already attached, the process is terminated.

  When the lens 14 is attached when the lens 14 is not already attached, a lens detection signal is input from the lens detection switch 26 to the signal processing unit 18 (S14). In response to this lens detection signal, the signal processing unit 18 sends a control signal to the optical unit moving motor 20 to move the image sensor 44 of the optical unit 16 to the adjustment start position SP of FIG. 3 (S16).

  In this state, the manual focus adjustment function of the lens 14 is operated by the operator. Note that the image sensor 16 is moved to the adjustment start position SP immediately after the lens is mounted, that is, before the manual focus operation. At this stage, the lens 14 is operated to adjust the angle of view.

  As described above, in the present embodiment, when the lens is mounted, the image sensor 44 only moves to the adjustment start position SP, and autofocus using the image sensor 44 is not performed. The focus is manually adjusted on the lens side, and is adjusted to the imaging surface located at the adjustment start position SP.

  Next, FIG. 5 shows an operation when an external trigger is input. When a trigger signal is input from the outside (S20), the signal processing unit 18 performs an autofocus operation (S22). In the autofocus operation, as described above, the signal processing unit 18 processes the captured image input from the optical unit 16 to obtain the frequency of the image, and determines whether or not the image is in focus based on the frequency. . Then, the signal processing unit 18 moves the optical unit 16 to a position where the focus is achieved. As a result, the optical unit 16 moves away from the adjustment start position.

  Here, the external trigger is input from a controller, for example. When the operator views the monitoring video on the monitor and determines that focus adjustment is necessary, the operator performs an operation for instructing the autofocus operation on the controller. The controller sends an operation instruction signal for instructing autofocus to the monitoring camera 10. This operation instruction signal is acquired by the signal processing unit 18 as an external trigger.

  The external trigger may be an input signal from a sensor. For example, it is assumed that the surveillance camera 10 is provided indoors. The monitoring camera 10 normally monitors the center of the room and monitors the vicinity of the door when the door is opened. In this case, a sensor for detecting opening and closing of the door is provided. A signal indicating opening / closing of the door is input to the surveillance camera 10 as an external trigger. When the door is opened, the signal processing unit 18 performs focus adjustment for focusing on the door. At this time, preferably, a rotation mechanism (not shown) is operated so that the camera is directed toward the door.

  The external trigger is not limited to the above example. Any trigger corresponding to a situation where it is determined that focus adjustment is necessary can be applied.

  Next, FIG. 6 shows the operation at the time of color / monochrome switching. As described above, the signal processing unit 18 switches between the color shooting mode and the monochrome shooting mode (S30). At this time, the signal processing unit 18 sends a control signal to the switching motor 24. As a result, the color / monochrome switching mechanism 22 operates to replace the infrared filter for the color photographing mode with the glass plate for the black and white photographing mode, or the reverse operation is performed. The signal processing unit 18 also performs an autofocus operation during the switching operation (S32). Thereby, it is possible to eliminate a focus shift caused by switching between color photography and monochrome photography.

  In the above-described embodiment, the autofocus operation is performed when the external trigger is input and when the color / monochrome switching operation is performed. However, the autofocus operation may be performed when an arbitrary condition corresponding to a situation where it is determined that focus adjustment is necessary. For example, the autofocus operation may be performed when the time is monitored and the day and night are switched. Alternatively, the autofocus operation may be performed periodically. The autofocus operation may be performed when the movement of the photographing object is detected. When infrared illumination is provided, an autofocus operation may be performed according to whether the illumination is on or off.

  In the above-described embodiment, the signal processing unit 18 determines whether the lens 14 is attached based on the lens detection signal of the lens detection switch 26. On the other hand, the signal processing unit 18 may detect the mounting of the lens 14 using another configuration. For example, the signal processing unit 18 may determine that the lens 14 is attached when the ALC connector 30 is removed. When the ALC connector 30 is removed, the lens 14 is replaced. Therefore, the signal processing unit 18 can determine that the lens 14 is attached when the ALC connector 30 is removed. When the ALC connector 30 is removed, the signal processing unit 18 moves the image sensor 44 to the adjustment start position SP.

  FIG. 7 shows a reduction effect of the focus adjustment moving range A according to the present embodiment. As shown in the upper part of FIG. 7, it is assumed that the image sensor 44 is at a position X in the focus adjustment moving range A before the lens is attached. The position X is deviated from the adjustment start position SP. When the lens attachment is detected, the image sensor 44 is moved to the adjustment start position SP. In this state, the lens 14 is focused manually. Therefore, the focus of the lens 14 is focused on the image sensor 44 at the adjustment start position SP. Thereafter, when an event such as an external trigger occurs, the image sensor 44 is moved from the adjustment start position SP, and autofocus is performed.

  Here, it is assumed that the processing of the present embodiment is not performed. In this case, even when the lens is mounted, the image sensor 44 is at the upper position X in FIG. 7, and in this state, manual focus adjustment using the lens 14 is performed. Therefore, when the lens is mounted, the image is focused on the image sensor 44 at the position X. In the subsequent autofocus operation, as indicated by a two-dot chain line in the upper part of FIG. The two-dot chain line region protrudes from the focus adjustment movement range A of the present embodiment. Therefore, the operable range of the image sensor 44 must be expanded.

  As shown in the above example, if this embodiment is not applied, it is necessary to move the image sensor 44 around the position, regardless of the focus position of the lens. It is necessary to increase the bill. On the other hand, in this embodiment, as described above, the adjustment allowance can be reduced by positioning the image sensor 44 at the adjustment start position SP when the lens is mounted. According to the present embodiment, the adjustment allowance can be suppressed to about 1 mm, for example.

  As described above, according to the imaging apparatus of the present embodiment, the signal processing unit 18 serving as the start element position control unit moves the image sensor 44 to the adjustment start position SP when the lens 14 is attached. Therefore, in the flange back adjustment in which the image sensor 44 is moved, it is only necessary that the image sensor 44 can be moved within the appropriate focus adjustment movement range A from the adjustment start position to the front and back. Therefore, the movement range of the image sensor 44 is reduced. Can be set. Since the moving range A of the image sensor 44 may be small, the image pickup apparatus can be downsized.

  The autofocus function can be realized by adjusting the flange back, which makes it possible to flexibly cope with movement of the subject and a significant change in the amount of light, thereby expanding the monitoring environment that can provide images. .

  In addition, according to the present embodiment, the signal processing unit 18 which is the element position control means controls the element position so as to be in focus in response to the trigger from the outside, so that an event of defocusing has occurred. Sometimes the focus can be adjusted automatically.

  In addition, according to the present embodiment, the signal processing unit 18 serving as the element position control means responds to switching between the normal photographing mode (color) and the infrared photographing mode (black and white) and adjusts the element position so as to be in focus. Since the control is performed, it is possible to automatically adjust the focus shift at the time of mode switching.

  Further, according to the present embodiment, the signal processing unit 18 that is the start element position control means moves the image sensor 44 to the adjustment start position SP in response to the removal of the ALC connector 30, and thus the ALC connector 30. It is possible to adjust the element position by detecting lens mounting by making good use of.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and it goes without saying that those skilled in the art can modify the above-described embodiments within the scope of the present invention.

  As described above, the imaging apparatus according to the present invention has an effect that the autofocus function by the flange back adjustment can be realized with a small configuration, and is useful as a surveillance camera or the like.

Block diagram of a surveillance camera in an embodiment of the present invention The figure which shows the flange back adjustment function of the surveillance camera in embodiment of this invention The figure which shows the position control of the image sensor at the time of lens mounting The flowchart for operation | movement description of the surveillance camera which concerns on embodiment of this invention The flowchart for operation | movement description of the surveillance camera which concerns on embodiment of this invention The flowchart for operation | movement description of the surveillance camera which concerns on embodiment of this invention The figure which shows the reduction effect of the focus adjustment movement range

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Surveillance camera 12 Camera main body 14 Lens 16 Optical part 18 Signal processing part 20 Optical part moving motor 22 Color / monochrome switching mechanism 24 Switching motor 26 Lens detection switch 28, 30 ALC connector 40 Camera housing 42 Lens mounting surface 44 Imaging element 46 Imaging surface FB Flange back A Focus adjustment movement range

Claims (4)

An image sensor;
Moving means for moving the image sensor in the optical axis direction;
An element position control means for controlling the moving means to move the image pickup element within a predetermined focus adjustment moving range so as to be in focus;
A lens attachment detection means for detecting lens attachment;
Start element position control means for moving the image sensor to a predetermined adjustment start position within the focus adjustment movement range when mounting of the lens is detected;
An imaging apparatus comprising:   The imaging device according to claim 1, wherein the element position control unit controls the element position so as to be in focus in response to an external trigger.   2. The imaging apparatus according to claim 1, wherein the element position control unit controls the element position so as to be in focus in response to switching between the normal imaging mode and the infrared imaging mode.   The image pickup device according to any one of claims 1 to 3, wherein the start element position control means moves the image pickup element to the adjustment start position in response to removal of a connector of an automatic iris adjuster. apparatus.

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