JP2009290537A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which can correctly select a tracking curve, according to light and which can accurately perform autofocusing. <P>SOLUTION: A surveillance camera 10 includes a zoom lens 12 and a focus lens 14. When the screen is dark, an IR cut filter 20a is eliminated. In this case, visible light and infrared light is made incident on a CCD image sensor 28. Autofocusing is performed for the whole range of a scanning range for the visible light and infrared light. When focusing is completed, it is determined as to whether the focus position lies within the scanning range for the visible light or within the scanning range for the infrared light. If the focus position lies within the scanning range for the visible light, a tracking curve for the visible light is selected. If the focus position is within the scanning range for the infrared light, a tracking curb for the infrared light is selected. If the focus position is within their overlapping range, the zoom lens 12 is moved toward the wide field of view, and then the process is restarted from autofocusing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus applied to a surveillance camera that captures an optical image of a subject through a zoom lens and a focus lens.

An example of this type of imaging apparatus is disclosed in Patent Document 1. According to the focus adjustment device of Patent Document 1, the user can arbitrarily attach an infrared cut filter to the front end of the lens barrel of the digital camera, and when the infrared cut filter is attached, The photographing drive range of the focus lens is selectively set when the outer cut filter is not attached. In this digital camera, it is determined whether an infrared cut filter is attached according to the pixel output level of a predetermined area of the CCD image sensor.
JP 2002-221656 [G02B 7/28, G02B 7/36, G03B 13/36, G03B 5/00, G03B 11/00]

  However, in the digital camera of this background art, it is the user who attaches and detaches the infrared cut filter, and it is not an appropriate configuration for use as a surveillance camera. Further, an infrared LED is provided in the digital camera, and the focus lens drive step position is set based on whether the infrared cut filter is attached and whether the infrared LED is turned on. Therefore, when the infrared LED is provided independently from the digital camera, an appropriate drive step position cannot be set. Furthermore, autofocus cannot be executed correctly.

  Therefore, a main object of the present invention is to provide a novel imaging device.

  Another object of the present invention is to provide an imaging apparatus capable of accurately performing autofocus even when an apparatus for irradiating a subject with infrared light is not provided.

  The present invention employs the following configuration in order to solve the above problems. The reference numerals in parentheses, supplementary explanations, and the like indicate correspondence relationships with embodiments described later to help understanding of the present invention, and do not limit the present invention in any way.

  The first invention is detachable, and outputs a filter that does not transmit infrared light but transmits visible light, and an image signal corresponding to a subject image formed on the image sensor via the filter and the imaging lens. The first relative position changing means for changing the first relative position of the imaging lens with respect to the image pickup device with the filter removed, and the in-focus position by changing the first relative position within the first predetermined range. A focus position detecting means for detecting the first position, and a first for determining whether or not the focus position is within a second predetermined range which is a part of the first predetermined range and is a scanning range corresponding to visible light. If it is determined by the determination means and the first determination means that the in-focus position is within the second predetermined range, the first relative position is changed based on the tracking characteristic for visible light, and the focusing operation is executed. First focusing control means for performing first discrimination When it is determined that the in-focus position is not within the second predetermined range by the step, the second in-focus is performed by changing the first relative position based on the tracking characteristic for infrared light and performing the in-focus operation. It is an imaging device provided with a control means.

  In the first invention, the imaging device (10) is detachable and includes a filter (20a) that transmits visible light without transmitting infrared light. The imaging means (28) outputs an image signal corresponding to the subject image formed on the imaging element via the filter and the imaging lens (14). The first relative position changing means (18, 34, S35) changes the first relative position of the imaging lens with respect to the imaging element in a state where the filter is removed. The in-focus position detecting means (34, S35, S37, S57, S59) detects the in-focus position by changing the first relative position within the first predetermined range (in the whole range in the embodiment). The first determination means (34, S39, S45, S61) is a part of the first predetermined range, and whether or not the in-focus position is located within the second predetermined range that is a scanning range corresponding to visible light. Is determined. The first focusing control means (34, S25), when it is determined by the first determination means that the in-focus position is within the second predetermined range (the flag 746 is turned on and the flag 748 is turned off), the imaging means Is determined to be visible light, and the first relative position is changed based on the tracking characteristic for visible light, and a focusing operation (autofocus) is performed. Further, the second focus control means (34, S25) determines that the focus position is not located within the second predetermined range by the first determination means (the flag 746 is turned off and the flag 748 is turned on). Then, it is determined that the light incident on the imaging unit is infrared light, and the focusing operation is performed by changing the first relative position based on the tracking characteristics of the infrared light.

  According to the first invention, the light applied to the subject is determined based on the result of autofocusing with the filter removed, and then autofocus is performed based on the tracking characteristics according to the determination result. Therefore, even if a device for irradiating a subject with infrared light is not provided, the correct tracking characteristic can be selected and autofocus can be executed accurately.

  A second invention is dependent on the first invention, and is provided on the subject side with respect to the imaging lens, and a zoom lens for enlarging the subject image to form an image on the imaging device, and a second zooming lens for the imaging device In the overlapping range where the second relative position changing means for changing the relative position, the second predetermined range, and a third predetermined range which is a part of the first predetermined range and which is a scanning range for infrared light overlap. Second discriminating means for discriminating whether or not the in-focus position is located, and when the in-focus position is discriminated to be within the overlapping range by the second discriminating means, the image sensor is detected by the second changing means. After the second relative position is changed to a position where the zoom lens and the zoom lens are separated from each other, the focus position detection means, the first determination means, and the first focus control means or the second focus control means are caused to function.

  In the second invention, the imaging apparatus further includes a zoom lens (12), a second relative position changing means (16, 34, S51), and a second determining means (34, S39, S45). The variable power lens is disposed on the subject side (front) of the imaging lens, and enlarges the subject image to form an image on the image sensor. The second relative position changing unit changes the second relative position of the variable power lens with respect to the image sensor. Whether the in-focus position is located in an overlapping range where the second predetermined range and a third predetermined range that is a part of the first predetermined range and is a scanning range for infrared light overlap. Determine whether or not. When it is determined by the second determining means that the in-focus position is within the overlapping range (“YES” in S39 and “YES” in S45), the position where the image pickup element and the zoom lens are separated by the second changing means After changing the second relative position (to the wide angle side), the focus position detection means, the first determination means, and the first focus control means or the second focus control means are caused to function.

  According to the second aspect, when the in-focus position detected by scanning the entire range is a range where the second predetermined range and the third predetermined range overlap, the zoom lens is placed at a position where they do not overlap. Since the in-focus position is detected again and it is determined whether or not it is within the second predetermined range, the incident light is accurately determined, and auto-focusing according to the correct tracking characteristics is executed. Can do.

  The third invention is a detachable filter that transmits visible light without transmitting infrared light, and outputs an image signal corresponding to a subject image formed on the image sensor through the filter and the imaging lens. Imaging means for performing the detection, a first relative position changing means for changing the first relative position of the imaging lens with respect to the imaging device, and a focus position detection for detecting the focus position by changing the first relative position within a first predetermined range. Means, a variable power lens that is disposed closer to the subject than the imaging lens, enlarges the subject image and forms the image on the imaging device, and a second relative position change that changes the second relative position of the variable magnification lens with respect to the imaging device After the second relative position is changed to a position where the image pickup device and the zoom lens are separated from each other by the means and the second changing means, the in-focus position detected by the in-focus position detecting means with the filter removed is the first position. Part of a given range When determining that the in-focus position is within the second predetermined range by the determining means for determining whether or not the position is within the second predetermined range that is the scanning range for visible light, Based on the tracking characteristic for visible light, the first focusing control unit that changes the first relative position to execute the focusing operation and the determining unit determine that the in-focus position is not within the second predetermined range. In this case, the imaging apparatus includes a second focus control unit that performs a focusing operation by changing the first relative position based on a tracking characteristic of infrared light.

  In the third invention, unlike the second invention, the zoom lens is suddenly moved to the wide-angle side, the focusing operation is executed for the entire range, and it is determined whether or not the focusing position is within the second predetermined range. I have to do it.

  Also in the third aspect of the invention, it is possible to determine the incident light and accurately execute autofocus according to the correct tracking characteristics.

  The fourth invention is a detachable filter that transmits visible light without transmitting infrared light, and outputs an image signal corresponding to the subject image formed on the image sensor via the filter and the imaging lens. Imaging means, a storage means for detecting the current first in-focus position in a state where the filter is mounted, and storing the first in-focus position, and a relative position changing means for changing the relative position of the imaging lens with respect to the imaging device And a focus position detecting means for detecting the second focus position by changing the relative position within a predetermined range with the filter removed, and detecting a difference between the first focus position and the second focus position. And a difference detection unit that performs a focusing operation by changing a relative position based on a tracking characteristic for infrared light when the difference detected by the difference detection unit is greater than a predetermined threshold. Focus control means, When the difference detected by the minute detection unit is equal to or smaller than a predetermined threshold, the imaging unit includes a second focus control unit that executes a focusing operation by changing a relative position based on a tracking characteristic for visible light. Device.

  In the fourth invention, the imaging device (10) is detachable and includes a filter (20a) that transmits visible light without transmitting infrared light. The imaging means (28) outputs an image signal corresponding to the subject image formed on the imaging element via the filter and the imaging lens (14). The storage means (34, 36, 74, S81) detects the current first in-focus position with the filter mounted, and stores the first in-focus position. The relative position changing means (18, 34) changes the relative position of the imaging lens with respect to the imaging device. The focus position detection means (34, S83, S91, S93) detects the second focus position by changing the relative position within a predetermined range with the filter removed. The difference detection means (34, S95) detects the difference between the first focus position and the second focus position. The first focus control means (34, S25) determines that the incident light is infrared light when the difference detected by the difference detection means is greater than a predetermined threshold (“YES” in S95). After the determination (flag 746 is turned off and flag 748 is turned on), the relative position is changed based on the tracking characteristics of infrared light, and the focusing operation is executed. The second focus control means (34, S25) determines that the incident light is visible light when the difference detected by the difference detection means is equal to or smaller than a predetermined threshold ("NO" in S95). Then, the flag 746 is turned on and the flag 748 is turned off, and the relative position is changed based on the tracking characteristic for visible light, and the focusing operation is executed.

  In the fourth invention, as in the first invention, the correct tracking characteristic can be selected and the autofocus can be executed accurately.

  According to the present invention, the light incident on the imaging unit is determined based on the result of autofocusing with the filter removed, and then autofocusing is performed based on the tracking characteristics according to the determination result. Even if a device for irradiating a subject with infrared light is not provided, the correct tracking characteristic can be selected and autofocus can be executed accurately.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  Referring to FIG. 1, surveillance camera 10 of this embodiment includes a zoom lens 12. The position (relative position) of the zoom lens 12 with respect to the CCD image sensor 28 is changed when the stepping motor 16 is driven by the CPU 34. For example, the zoom lens 12 moves back and forth along the optical axis by a feed screw mechanism (not shown) using a stepping motor 16. Therefore, the subject image is enlarged (zoomed in) or reduced (zoomed out) to an arbitrary magnification.

  In this embodiment, a CCD image sensor is used as the imaging device, but a CMOS image sensor may be used instead.

  A focus lens 14 is provided inside the zoom lens 12. That is, the zoom lens 12 is arranged in front of the focus lens 14 (subject side). The position (relative position) of the focus lens 14 with respect to the CCD image sensor 28 is changed by driving the stepping motor 18 by the CPU 34 in conjunction with the movement of the zoom lens 12. Specifically, the focus lens 14 is moved back and forth along the optical axis by a feed screw mechanism (not shown) using a stepping motor 18 and forms a subject image on the light receiving surface of the CCD image sensor 28. To do.

  The light transmitted through the focus lens 14 is incident on the light receiving surface of the CCD image sensor 28 via the optical filter 20 and the color filter 26. Although not shown, the optical filter 20 is formed in a plate shape, and the upper half is formed of an IR cut filter (infrared light cut filter) 20a that cuts infrared light (wavelength component of 700 nm or more). The lower half is formed of glass (hereinafter referred to as “dummy filter”) 20b. The optical filter 20 is moved in the length direction (vertical direction in FIG. 1) by a feed screw mechanism (not shown) using a stepping motor 24 controlled by the CPU 34. Therefore, on the optical axis between the focus lens 14 and the CCD image sensor 28, an IR cut filter is used according to the external brightness, strictly, according to the type of light (visible light or infrared light). One of 20a and dummy filter 20b is arranged.

  When the outside is bright, the IR cut filter 20a is disposed on the optical axis, only visible light is transmitted, and infrared light is removed. On the other hand, when the outside is dark, the dummy filter 20b is disposed on the optical axis, and infrared light is transmitted together with visible light. The reason why the glass filter 20b is inserted instead of the IR cut filter 20a is to make the optical path length the same as when the IR cut filter 20a is inserted.

  However, which of the IR cut filter 20a and the dummy filter 20b is arranged on the optical axis is detected by the state sensor 22 such as an optical sensor, and the detection signal is given to the CPU.

  The color filter 26 is a Bayer array primary color filter. Therefore, the amount of charge generated by each of the plurality of light receiving elements formed on the light receiving surface of the CCD image sensor 28 reflects the light quantity of R (Red), G (Green), or B (Blue).

  The charge accumulated in each element of the CCD image sensor 28, that is, the image signal (RGB signal) is read from the CCD image sensor 28 and then subjected to noise removal by the correlated double sampling in the CDS circuit 30. Next, the AGC circuit 38 performs gain adjustment, and the A / D converter 40 converts image data (R data, G data, B data) that is a digital signal.

  Reading of the image signal from the CCD image sensor 28, noise removal by the CDS circuit 30, and conversion to image data by the A / D converter 40 are executed in response to a timing signal output from the TG 32. Further, based on a luminance signal ("Y data" described later) input from the D / A converter 50 described later to the CPU 34, the CPU 34 determines whether to set the photographing mode to the daytime mode or the nighttime mode. . That is, the CPU 34 determines whether the outside of the monitoring camera 10 or the screen (captured image) is bright or dark based on the level of the luminance signal, and selectively sets the shooting mode. Further, the CPU 34 adjusts the gain of the AGC circuit 38 based on the determination result.

  The signal processing circuit 42 performs a series of processes such as color separation, white balance adjustment, and YUV conversion on the image data output from the A / D converter 40. Therefore, Y data as a luminance component and U data and V data (U: RY, V: BY) as color difference components are generated.

  The U data and V data are supplied to the color processing signal circuit 44, and the Y data is supplied to the luminance processing circuit 46. The color processing signal circuit 44 converts the applied U data and V data into carrier color data including a color burst signal, and the luminance processing circuit 46 includes the applied Y data including a horizontal synchronizing pulse and a vertical synchronizing pulse. Convert to luminance data.

  The carrier color data is converted into a carrier color signal which is an analog signal by the D / A converter 48, and the converted carrier color signal is subjected to noise removal by a BFP 52 having a center frequency of 3.58 MHz. The luminance data is converted into an analog luminance signal by the D / A converter 50, and the converted luminance signal is subjected to noise removal by the LPF 54 having a cutoff frequency of 6.0 MHz. The carrier color signal and the luminance signal from which noise has been removed are added to each other by an adder 56, thereby generating an NTSC composite video signal. The generated composite video signal is output from the output terminal 58 and recorded on a recording medium by, for example, a video recorder (not shown).

  Further, the CPU 34 turns on / off the D / A converter 48 based on the luminance signal from the D / A converter 50. That is, the CPU 34 shoots in daytime mode when the magnitude (level) of the luminance signal is larger than a preset threshold value (hereinafter, sometimes referred to as “first threshold value” for convenience of explanation). Then, the stepping motor 24 is controlled to enable the IR cut filter 20a, and the D / A converter 48 is turned on. As a result, a color composite video signal is output from the output terminal 58.

  Although illustration is omitted, the surveillance camera 10 is provided with an aperture mechanism. When the aperture is set to the minimum, if the luminance signal is larger than the first threshold value, the screen (captured image) is bright. Judging and shooting in daytime mode.

  On the other hand, when the level of the luminance signal is smaller than a preset threshold value (hereinafter, sometimes referred to as “second threshold value” for convenience of explanation), the CPU 34 takes a picture in the night mode, and thus the stepping motor 24. And the IR cut filter 20a is disabled, that is, the dummy filter 20b is enabled, and the D / A converter 48 is turned off. As a result, a monochrome composite video signal is output from the output terminal 58.

  However, when the aperture is set to the maximum and the luminance signal is amplified to the maximum, if the amplified luminance signal is smaller than the second threshold, it is determined that the screen is dark and shooting is performed in the night mode. It is.

  It should be noted that the first threshold value and the second threshold value are larger than the second threshold value, and these values are obtained empirically in advance by a test or the like.

  Also, once the daytime mode is set, shooting is performed in the daytime mode until the level of the luminance signal becomes smaller than the second threshold value. Conversely, once the nighttime mode is set, the luminance signal Shooting is performed in the night mode until the level exceeds the first threshold.

  The flash memory 36 stores a control program corresponding to processing executed by the CPU 34, tracking curve data for visible light, tracking curve data for infrared light, various threshold values, and the like.

  Furthermore, the surveillance camera 10 is attached to a pan head (not shown) capable of controlling (setting) its elevation angle (tilt) and turning angle (pan), and has a motor 60 and a turning angle for controlling the elevation angle. A motor 62 for control is attached to the pan head. Driving of the motors 60 and 62 is controlled by the CPU 34. However, the driving of the motors 60 and 62 may be controlled not by the CPU 34 but by a host computer (not shown). In such a case, the host computer notifies the CPU 34 that the motors 60 and 62 have been driven and controlled.

  For example, such a surveillance camera 10 records a video with the zoom lens 12 fixed at a low magnification position regardless of day or night, and when a suspicious person is found, tracking curve data stored in the flash memory 36. The zoom lens 12 is moved in a state where the suspicious person is in focus, and an image in which the suspicious person is enlarged is recorded.

  Therefore, the CCD image sensor 28 of this embodiment has high sensitivity not only for visible light but also for infrared light. For this reason, when the light from the subject is directly incident on the CCD image sensor 28 when the outside is bright as in the daytime, the reproduced color is reddish. For this reason, an IR cut filter 20a is inserted between the focus lens 14 and the CCD image sensor 28 to remove infrared light, realizing a color reproducibility comparable to that seen by human eyes.

  On the other hand, when the outside is dark, such as at night, a sufficient amount of light cannot be obtained with only visible light. For this reason, a dummy filter 20b is inserted in place of the IR cut filter 20a, and not only visible light but also infrared light is incident to secure a necessary amount of light. At this time, since white balance cannot be obtained in the color image, the D / A converter 48 is turned off to switch to the monochrome image.

  However, in a situation where the night mode is set, the subject is irradiated with infrared light from a light emitting device (not shown) such as an infrared LED. This is to ensure the necessary amount of light. However, in this embodiment, the light emitting device is provided separately from the monitoring camera 10.

  FIG. 2 is a graph showing an example of a tracking curve of visible light (when there is no infrared light) when the monitoring camera 10 of this embodiment is used. In the graph shown in FIG. 2, the horizontal axis indicates the position of the zoom lens 12, and the vertical axis indicates the position of the focus lens 14. In the graph shown in FIG. 2, the higher the horizontal direction of the horizontal axis, the higher the zoom ratio, and the higher the vertical axis, the closer the focus is. That is, the zoom lens 12 approaches the CCD image sensor 28 as it goes to the right on the horizontal axis, and the zoom lens 12 moves away from the CCD image sensor 28 as it goes to the left on the horizontal axis. Further, the focus lens 14 approaches the CCD image sensor 28 as it goes upward along the vertical axis, and the focus lens 14 moves away from the CCD image sensor 28 as it goes downward along the vertical axis.

  In the graph shown in FIG. 2, a waveform (tracking curve) indicated by a solid line indicates a positional relationship between the zoom lens 12 and the focus lens 14 with respect to a subject present at a distance of 1.5 m from the monitoring camera 10. On the other hand, a tracking curve indicated by a dotted line indicates a positional relationship between the zoom lens 12 and the focus lens 14 with respect to a subject at infinity from the monitoring camera 10. Therefore, based on such tracking characteristics, when photographing a subject existing at a position more than 1.5 m away from the surveillance camera 10, the focus lens is positioned at the position of the zoom lens 12. On the other hand, it is understood that the position of the focus lens 14 may be moved between the solid line and the dotted line.

  Further, as described above, since the surveillance camera 10 continuously performs shooting processing regardless of day and night, the shooting mode (daytime mode / nighttime mode) is set between daytime (bright) and nighttime (dark). It is necessary to switch. In this embodiment, when it is bright, the daytime mode is set, and the position of the focus lens 14 is adjusted in conjunction with the zoom lens 12 according to the tracking curve for visible light. On the other hand, when it is dark, the night mode is set, and the position of the focus lens 14 is adjusted in conjunction with the zoom lens 12 according to the tracking curve for infrared light.

  For example, such a shooting mode can be automatically switched according to time (time zone). However, depending on the installation location of the surveillance camera 10, the brightness may be reversed between daytime and nighttime due to the use of lighting, and the night mode is actually set when it is dark. When it is bright, daytime mode needs to be set.

  FIG. 3 is a graph showing an example of a tracking curve for visible light and a tracking curve for infrared light. Also in FIG. 3, the horizontal axis indicates the position of the zoom lens 12, and the vertical axis indicates the position of the focus lens 14.

  As can be seen from FIG. 4, which is an enlarged view of a part surrounded by a dotted circle in FIG. 3, in the case of visible light on the low magnification side where the position of the zoom lens 12 is close to the CCD image sensor 28. Scanning range of the focus lens 14 (the shaded area in FIG. 4 (visible light area in black and white mode and color mode). The same applies to FIGS. 3 and 5) and the scanning range of the focus lens 14 in the case of infrared light (A region with a dark diagonal line in FIG. 4 (infrared light region in black and white mode; the same applies to FIGS. 3 and 5) is distinguishable (separated).

  On the other hand, as can be seen from FIG. 5 which is an enlarged view of a part surrounded by a two-dot chain line circle in FIG. 3, on the high magnification side where the position of the zoom lens 12 is far from the CCD image sensor 28, There is a range where the scanning range of the focus lens 14 in the case of visible light and the scanning range of the focus lens 14 in the case of infrared light overlap (a region with a thin diagonal line in FIG. 5).

  For example, at the zoom position A shown in FIG. 5, as shown in FIG. 6A, the scanning range for visible light and the scanning range for infrared light are continuously joined in the movable range of the focus lens 14. ing. However, in FIG. 6A (the same applies to FIG. 6B), the left side is the direction in which the focus lens 14 moves away from the CCD image sensor 28 (goes above the vertical axis in FIGS. 3 and 4). The right side is the direction in which the focus lens 14 approaches the CCD image sensor 28 (goes below the vertical axis in FIGS. 3 and 4).

  Further, at the zoom position B shown in FIG. 5, as shown in FIG. 6B, the scanning range for visible light and the scanning range for infrared light partially overlap each other and overlap each other (overlapping). Range) exists.

  Although illustration is omitted, when the zoom position is set further to the left than the zoom position A in FIG. 5, it is between the scanning range for visible light and the scanning range for infrared light. There is a range (blank area) that does not correspond to (see FIG. 4).

  As can be seen from FIGS. 3 to 5, the tracking curve for visible light and the tracking curve for infrared light are significantly different. Therefore, the IR cut filter 20a is removed, that is, the dummy filter 20b is attached, and in a state where visible light and infrared light can enter the CCD image sensor 28, the IR cut filter 20a is correct according to the incident light. It is necessary to set the position of the focus lens 14 interlocked with the zoom lens 12 according to the tracking curve. That is, since the scanning range of the position of the focus lens 14 is different between visible light and infrared light, it always takes a lot of time to focus when the entire range is scanned.

  Therefore, in this embodiment, based on the characteristics of the visible light and infrared light tracking curves as described above, the type of light is accurately determined, an appropriate tracking curve is selected, and the selected tracking curve is followed. Auto focus is executed. Hereinafter, the means or method will be described.

  For example, at the start of shooting or during shooting, an IR cut filter 20a or a dummy filter 20b is appropriately attached and a tracking curve for visible light or infrared light is selected according to changes in screen brightness. . When the screen is dark, the IR cut filter 20a is removed and the dummy filter 20b is attached as described above. In such a case, since visible light and infrared light are incident on the CCD image sensor 28, the position of the focus lens 14 that is linked to the zoom lens 12 is controlled according to either the visible light or the infrared light tracking curve. Must be determined (selected). Therefore, in such a case, a range (hereinafter referred to as “entire range”) that is a combination of the scanning range for visible light and the scanning range for infrared light is set as the scanning range of the focus lens 14, and autofocusing is performed. To focus (focus). When focusing is completed and the position of the focus lens 14 (in-focus position) is within the scanning range for visible light, a visible light tracking curve is selected, and the in-focus position is scanned for infrared light. If it is within the range, an infrared light tracking curve is selected.

  However, when the screen is bright and the IR cut filter 20a is attached, infrared light is removed and only visible light is incident on the CCD image sensor 28. In this case, a visible light tracking curve is generated. Selected.

  However, if the focus position is within the overlapping range shown in FIG. 5 and FIG. 6 as a result of executing autofocus for the entire range as described above, a tracking curve for visible light or infrared light is selected. Can not do it. Therefore, in such a case, the zoom lens 12 is forcibly moved to the wide angle (low magnification) side, that is, the zoom lens 12 is moved to a position away from the CCD image sensor 28, and autofocus is executed again for the entire range. Is done. Then, whether the in-focus position is within the scanning range for visible light or the scanning range for infrared light is detected, and a tracking curve for visible light or infrared light is selected.

  However, since the tracking curves of visible light and infrared light are acquired in advance by testing or the like, as shown in FIGS. 4 and 5, the scanning range for visible light and the scanning range for infrared light are separated. The position of the zoom lens 12 thus made can also be known in advance. Therefore, when the zoom lens 12 is moved to the wide-angle side, the zoom lens 12 is moved to a position where the scanning range for visible light and the scanning range for infrared light are separated (a predetermined position). The stepping motor 16 is driven and controlled so that

  FIG. 7 is an illustrative view showing one example of a memory map 70 of the flash memory 36 shown in FIG. As shown in FIG. 7, the flash memory 36 includes a program storage area 72 and a data storage area 74. The program storage area 72 stores a monitoring processing program of the monitoring camera 10, and this monitoring processing program includes an imaging processing program 720, a zoom processing program 722, a focus processing program 724, a focus determination program 726, and a focus position range determination. The program 728 and the tracking curve selection program 730 are configured.

  The imaging processing program 720 is a program that mainly controls the driving of the TG 32. As described above, in response to the timing signal output from the TG 32, the image signal is read from the CCD image sensor 28, and is read by the CDS circuit 30. Noise removal and conversion into image data by the A / D converter 40 are executed. Further, the imaging processing program 720 executes switching between the IR cut filter 20a and the dummy filter 20b according to the level of the luminance signal. At this time, the photographing processing program 720 turns on / off a filter flag 744 described later.

  The zoom processing program 722 is a program for zooming in or zooming out. Specifically, the CPU 34 controls the driving of the stepping motor 16 to displace the zoom lens 12. However, as described above, the zoom instruction may be input as a trigger when a suspicious person is found, or may be input by the user.

  The focus processing program 724 is a program for executing autofocus and focusing. More specifically, the CPU 34 drives the stepping motor 18 to change the focus lens 14 when the captured image changes due to panning / tilting of the surveillance camera 10 or due to a change in the subject or external brightness. Move. However, as described above, when the zoom lens 12 is moved, the focus lens 14 is also moved in accordance with the tracking curve.

  Although detailed description is omitted, a change in the captured image due to a change in the subject can be determined as follows. For example, a value (evaluation value) obtained by integrating high-frequency components of a captured image is monitored, and it can be determined that the subject has changed when the evaluation value increases or decreases beyond a certain threshold.

  The in-focus position range discriminating program 726, in a tracking curve selection process according to a tracking curve selection program 730 to be described later, the in-focus position belongs to either the scanning range for visible light, the scanning range for infrared light, or their overlapping range. This is a program for determining whether or not. The tracking curve selection program 730 executes autofocus for the entire range when the brightness of the screen (captured image or outside) changes, and irradiates the subject according to the focus position when the focus is achieved. Identify the type of light and select a visible or infrared tracking curve. Specifically, if the light applied to the subject is visible light, a visible light range flag 746 described later is turned on, and an infrared light range flag 748 is turned off. In this case, the visible light tracking curve is Selected. On the other hand, if the light applied to the subject is infrared light, the visible light range flag 746 is turned off and the infrared light range flag 748 is turned on. In this case, the infrared light tracking curve is selected. .

  However, as a result of executing autofocus for the entire range, if the focal position when the focus is achieved is within the overlapping range, the zoom lens 12 is displaced to the low magnification side (wide angle side), and the entire range is again displayed. The focus operation is executed for the light source, the light type is specified according to the focus position when the focus is achieved, and the tracking curve of visible light or infrared light is selected.

  Although illustration is omitted, the program storage area 72 also stores other programs necessary for controlling the surveillance camera 10.

  In the data storage area 74, visible light tracking data 740 and infrared light tracking data 742 are stored, and a filter flag 744, a visible light range flag 746, and an infrared light range flag 748 are provided.

  The visible light tracking data 740 is data regarding a tracking curve of visible light, and is graph data obtained empirically in advance by a test or the like. The infrared light tracking data 742 is data on a tracking curve of infrared light, and is graph data obtained empirically, like the visible light tracking data 740.

  The filter flag 744 is a flag for determining whether the IR cut filter 20a or the dummy filter 20b is mounted on the optical axis. The filter flag 744 is composed of a 1-bit register. When the flag 744 is turned on (established), a data value “1” is set in the register, and conversely, the flag 744 is turned off (not established). Then, a data value “0” is set in the register. However, in this embodiment, the filter flag 744 is turned on when the IR cut filter 20a is mounted on the optical axis, and the filter flag 744 is turned off when the dummy filter 20b is mounted on the optical axis. Is done.

  The visible light range flag 746 indicates whether or not to scan the scanning range for visible light in the entire range determined by the tracking curve of visible light and infrared light when the focus lens 14 is displaced in autofocus. This is a flag for determining whether or not. The visible light range flag 746 is composed of a 1-bit register. When this flag 746 is turned on, a data value “1” is set in the register. Conversely, when this flag 746 is turned off, The data value “0” is set. However, in this embodiment, when the scanning range for visible light is set (including the case where the entire range is set), the visible light range flag 746 is turned on, and the scanning range for visible light is set. If not, the visible light range flag 746 is turned off.

  The infrared light range flag 748 should scan the scanning range for infrared light in the entire range determined by the tracking curve of visible light and infrared light when the focus lens 14 is displaced in autofocus. It is a flag for determining whether or not. The infrared light range flag 748 is also composed of a 1-bit register. When the flag 748 is turned on, a data value “1” is set in the register, and conversely, when the flag 748 is turned off, A data value “0” is set in the register. However, in this embodiment, when the scanning range for infrared light is set (including the case where the entire range is set), the infrared light range flag 748 is turned on, and the scanning range for infrared light is set. Is not set, the infrared light range flag 748 is turned off.

  Although not shown, the data storage area 74 stores other data, or is provided with other registers, counters (timers), or the like.

  Specifically, the CPU 34 shown in FIG. 1 executes the monitoring process shown in FIGS. As shown in FIG. 8, when starting the monitoring process, the CPU 34 executes an initialization process in step S1. Here, initial values are set in the visible light range flag 746 and the infrared light range flag 748. This initial value may be determined in advance or may be set by the user.

  Next, in step S3, photographing is started, and in step S5, it is determined whether or not the IR cut filter 20a is attached. That is, the CPU 34 determines whether or not the filter flag 744 is on. However, as described above, the CPU 34 determines whether the IR cut filter 20a or the dummy filter 20b is mounted based on the output from the sensor 22, and turns on / off the filter flag 744. .

  If “YES” in the step S5, that is, if the IR cut filter 20a is attached, the process directly proceeds to a step S17 shown in FIG. On the other hand, if “NO” in the step S5, that is, if the dummy filter 20b is attached, it is determined whether or not the screen is bright in a step S7. That is, it is determined whether or not the level of the luminance signal exceeds the first threshold value.

  If “NO” in the step S7, that is, if it is determined that the luminance signal level does not exceed the first threshold value and the screen is not bright, the process proceeds to a step S27 shown in FIG. 9 as it is. On the other hand, if “YES” in the step S7, that is, if the luminance signal level exceeds the first threshold value and the screen is determined to be bright, the IR cut filter is set in a step S9 to set the daytime mode. At step S11, the filter flag 744 is turned on. Subsequently, the visible light range flag 746 is turned on in step S13, the infrared light flag 748 is turned off in step S15, and the process proceeds to step S17. That is, when the IR cut filter 20a is attached, only visible light is incident, and therefore the visible light tracking curve is selected by the processing in steps S13 and S15.

  As shown in FIG. 9, in step S17, it is determined whether or not the screen is dark. That is, it is determined whether or not the level of the luminance signal is less than the second threshold value. If “NO” in the step S17, that is, if it is determined that the level of the luminance signal is equal to or higher than the second threshold and the screen is not dark, the process proceeds to a step S25 as it is. On the other hand, if “YES” in the step S17, that is, if it is determined that the level of the luminance signal is less than the second threshold value and the screen is dark, the IR cut filter is set in a step S19 to set the night mode. 20a is removed, and the filter flag 744 is turned off in step S21. Then, in step S23, a tracking curve selection process (see FIGS. 10 and 11) described later is executed, and the process proceeds to step S25.

  In step S25, other processing is executed, and the process returns to step S5. For example, in step S25, zoom processing is executed, and in conjunction with this, the focus lens 14 is moved and autofocus is executed. The same applies hereinafter.

  As described above, “NO” is determined in the step S7, and when the process proceeds to the step S27, it is determined whether or not there is a pan / tilt operation. That is, it is determined whether or not drive control of at least one of the motor 60 and the motor 62 is performed. If “NO” in the step S27, that is, if there is no pan / tilt operation, the process proceeds to a step S25 as it is. On the other hand, if “YES” in the step S27, that is, if there is a pan / tilt operation, the process proceeds to a step S23 to execute a tracking curve selecting process. As described above, even when there is a pan / tilt operation, the tracking curve selection process is executed when the pan / tilt operation (operation) is performed on a dark screen and the subject is irradiated. This is because the light that is emitted may change from visible light to infrared light, or from infrared light to visible light.

  10 and 11 are flowcharts (subroutines) of the tracking curve selection process shown in step S23 of FIG. As shown in FIG. 10, when the CPU 34 starts the tracking curve selection process, the visible light range flag 746 is turned on in step S31, the infrared light range flag 748 is turned on in step S33, and the autofocus is executed in step S35. To start. That is, the CPU 34 performs autofocus for the entire range including the visible light investigation range and the infrared light investigation range.

  In the next step S37, it is determined whether or not focusing has been completed. Here, it is determined whether or not the in-focus position where the evaluation value of the high frequency component of the luminance signal is the maximum value is detected. The same applies hereinafter. If “NO” in the step S37, that is, if the focusing is not completed, the process returns to the step S37 as it is and the autofocus (scanning of the focusing position) is continued. On the other hand, if “YES” in the step S37, that is, if the focusing is completed, it is determined that the focusing position is detected, and the focusing position is in the visible light range (scanning range for visible light) in the step S39. To determine whether it is within.

  If “YES” in the step S39, that is, if the in-focus position is within the visible light range, the process proceeds to a step S45. On the other hand, if “NO” in the step S39, that is, if not in the visible light range, it is determined that the in-focus position is in the infrared light range and the incident light is determined to be infrared light. To do. In step S41, the visible light range flag 746 is turned off. In step S43, the infrared light range flag 748 is turned on, and the process returns to the monitoring process shown in FIGS. That is, the tracking curve of infrared light is selected by the processing in steps S41 and S43. Therefore, until the next tracking curve selection process is executed, autofocus is executed according to the tracking curve of infrared light.

  In step S45, it is determined whether the in-focus position is within the infrared light range (within the scanning range for infrared light). If “YES” in the step S45, that is, if the in-focus position is in the infrared light range, the process proceeds to a step S51 shown in FIG. On the other hand, if “NO” in the step S45, that is, if the in-focus position is out of the infrared light range, it is determined that the incident light is visible light. In step S47, the visible light range flag 746 is turned on. In step S49, the infrared light range flag 748 is turned off, and the process returns to the monitoring process. In other words, a visible light tracking curve is selected by the processing in steps S47 and S49. Therefore, until the next tracking curve selection process is executed, the autofocus is executed according to the visible light tracking curve.

  As shown in FIG. 11, in step S51, the zoom lens 12 is moved to the wide angle side. Here, as described above, the CPU 34 drives and controls the stepping motor 16 so as to move the zoom lens 12 to a predetermined position. Next, in step S53, the visible light range flag 746 is turned on, in step S55, the infrared light range flag 748 is turned on, and in step S57, autofocus is started. That is, autofocus is executed for the entire range.

  In step S59, it is determined whether or not focusing is completed. If “NO” in the step S59, that is, if focusing is not completed, the process returns to the same step S59, and the autofocus (scanning) is continued. On the other hand, if “YES” in the step S59, that is, if the focusing is completed, it is determined whether or not the focusing position is in the infrared light range in a step S61.

  If “YES” in the step S61, that is, if the in-focus position is in the infrared light range, the visible light range flag 746 is turned off in a step S63, and the infrared light range flag 748 is turned on in a step S748. Then, the process returns to the monitoring process as shown in FIG. That is, an infrared light tracking curve is selected by the processing in steps S63 and S65.

  On the other hand, if “NO” in the step S61, that is, if the in-focus position is within the visible light range, the visible light range flag 746 is turned on in a step S67, and the infrared light range flag 748 is turned off in a step S69. Then, the process returns to the monitoring process. That is, the tracking curve of visible light is selected by the processing in steps S67 and S69.

  According to this embodiment, with the IR cut filter removed, autofocus is performed for the entire range including the scanning range for visible light and the scanning range for infrared light, and the in-focus position is in any scanning range. In this case, it is determined whether the light applied to the subject is visible light or infrared light, and the tracking curve for visible light or infrared light is selected according to the determination result. Even when a device for irradiating a subject with external light is provided separately from the monitoring camera, autofocus can be executed accurately.

  Further, as a result of executing autofocus for the entire range with the IR cut filter removed, when the in-focus position is within the overlapping range of the scanning range for visible light and the scanning range for infrared light, Since the zoom lens is moved to the wide-angle side, autofocus is performed at the position of the zoom lens where the scanning range for visible light and the scanning range for infrared light are separated, so a tracking curve for visible light or infrared light Can be selected reliably.

  In this embodiment, in the tracking curve selection process, when the in-focus position when the in-focus is completed by the first autofocus is included in both the visible light range and the infrared light range, the zoom lens is moved to the wide angle side. , And autofocus was performed again, and the tracking curve for visible light or infrared light was selected, but the zoom lens was moved to the wide-angle side from the beginning of the tracking curve selection process, Auto-focusing may be executed and a tracking curve of visible light or infrared light may be selected at a time. In such a case, it is only necessary to execute the processing of steps S51 to S69 shown in FIG.

  Since the surveillance camera 10 of the other embodiment is the same as the above-described embodiment except that the tracking curve selection process (S23) is different, a duplicate description is omitted. Hereinafter, a tracking curve selection process according to another embodiment will be described. FIG. 12 is a graph showing a part of another example of the tracking curve of visible light and infrared light. In FIG. 12, the horizontal axis is the position of the zoom lens 12, and the vertical axis is the position of the focus lens 14. In the graph shown in FIG. 12, the waveform indicated by the solid line is a visible light tracking curve that indicates the positional relationship between the zoom lens 12 and the focus lens 14 with respect to a subject that is located 1.5 m away from the monitoring camera 10. On the other hand, a waveform indicated by a dotted line is a tracking curve of infrared light indicating the positional relationship between the zoom lens 12 and the focus lens 14 with respect to a subject existing at a distance of 1.5 m from the monitoring camera 10.

  In the tracking curve selection process of this other embodiment, when the IR cut filter 20a is attached, that is, in a state where only visible light is incident on the CCD image sensor 28, when the screen becomes dark, the current focus position is determined. The reference in-focus position Fc (reference in-focus position data 750) is stored in the flash memory 36. Next, the IR cut filter 20a is removed, and autofocus is executed for the entire range. Then, it is determined whether or not the in-focus position is more than a predetermined value from the reference in-focus position Fc. However, the fixed value is set to a value empirically obtained by a test or the like. As can be seen from FIG. 12, when the in-focus position is separated from the reference in-focus position Fc by a certain value or more, a scanning range for infrared light is set. On the other hand, when the in-focus position is separated from the reference in-focus position Fc by less than a certain value, a scanning range for visible light is set.

  Therefore, as shown in FIG. 13, in another embodiment, when the tracking curve selection process is executed in accordance with the tracking curve selection program 730, data of the reference focus position Fc (reference focus position data) is stored in the data storage area 74. 750 is further stored.

  Specifically, the CPU 34 executes a flowchart of the tracking curve selection process shown in FIG. The monitoring process is the same as that in the above-described embodiment, and thus illustration and description thereof are omitted. The same processing as that described in the above embodiment will be briefly described.

  As shown in FIG. 14, when starting the tracking curve selection process, the CPU 34 stores the current focus position as the reference focus position Fc in step S81. That is, the reference focus position data 750 is stored in the data storage area 74. Next, the visible light range flag 746 is turned on in step S83, the infrared light range flag 748 is turned on in step S85, and autofocus is started in step S87.

  Subsequently, in step S89, it is determined whether or not focusing is completed. If “NO” in the step S89, the process returns to the same step S89 as it is. On the other hand, if “YES” in the step S89, it is determined whether or not the in-focus position-the reference in-focus position Fc is a predetermined value or more in a step S91. That is, it is determined whether or not the in-focus position is apart from the reference in-focus position Fc by a certain value or more.

  If “YES” in the step S91, that is, if the in-focus position-the reference in-focus position Fc is equal to or larger than a predetermined value, the visible light range flag 746 is turned off in a step S93, and the infrared light flag 748 is set in a step S95. To return to the monitoring process. On the other hand, if “NO” in the step S91, that is, if the in-focus position-the reference in-focus position Fc is less than a certain value, the visible light range flag 746 is turned on in a step S97, and the infrared light is detected in a step S99. The range flag 748 is turned off, and the process returns to the monitoring process.

  In other embodiments, it is possible to correctly select a tracking curve and execute autofocus accurately.

FIG. 1 is a block diagram showing an electrical configuration of a surveillance camera according to an embodiment of the present invention. FIG. 2 is a graph showing an example of a visible light tracking curve when the monitoring camera shown in FIG. 1 is used. FIG. 3 is a graph showing an example of tracking curves of visible light and infrared light when the monitoring camera shown in FIG. 1 is used. FIG. 4 is an enlarged view of a part of the graph shown in FIG. 3 on the low magnification side. FIG. 5 is an enlarged view in which a part on the high magnification side of the graph shown in FIG. 3 is enlarged. FIG. 6 is an illustrative view showing a scanning range for visible light and a scanning range for infrared light when autofocusing is performed in accordance with the zoom position according to the tracking curve of the visible light and infrared term shown in FIG. FIG. 7 is an illustrative view showing a memory map of the flash memory shown in FIG. FIG. 8 is a flowchart showing a part of the monitoring process of the CPU shown in FIG. FIG. 9 is another part of the CPU monitoring process shown in FIG. 1, and is a flowchart subsequent to FIG. FIG. 10 is a flowchart showing a part of the tracking curve selection process of the CPU shown in FIG. 11 is another part of the tracking curve selection process of the CPU shown in FIG. 1, and is a flowchart subsequent to FIG. FIG. 12 is a graph showing another example of visible light and infrared light tracking curves when the monitoring camera shown in FIG. 1 is used. FIG. 13 is an illustrative view showing a memory map of a flash memory according to another embodiment. FIG. 14 is a flowchart showing tracking curve selection processing of the CPU of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Surveillance camera 12 ... Zoom lens 14 ... Focus lens 16, 18 ... Stepping motor 20a ... IR cut filter 20b ... Glass filter 28 ... CCD
34 ... CPU

Claims (4)

A detachable filter that transmits visible light without transmitting infrared light; and
Imaging means for outputting an image signal corresponding to a subject image formed on an image sensor via the filter and the imaging lens;
First relative position changing means for changing a first relative position of the imaging lens with respect to the imaging element in a state where the filter is removed;
A focus position detecting means for detecting the focus position by changing the first relative position within a first predetermined range;
First determination means for determining whether or not the in-focus position is within a second predetermined range that is a part of the first predetermined range and that is a scanning range corresponding to the visible light;
When it is determined by the first determining means that the in-focus position is within the second predetermined range, the first relative position is changed based on the tracking characteristic for the visible light, and the focusing operation is performed. First focusing control means to be executed;
When the first determining means determines that the in-focus position is not located within the second predetermined range, the first relative position is changed based on the tracking characteristics of the infrared light to focus. An imaging apparatus comprising second focus control means for executing an operation. A zoom lens that is disposed closer to the subject than the imaging lens and enlarges the subject image to form an image on the imaging device;
Second relative position changing means for changing a second relative position of the zoom lens with respect to the image sensor;
Whether or not the in-focus position is within an overlapping range that overlaps the second predetermined range and a third predetermined range that is a part of the first predetermined range and that is a scanning range for the infrared light. And a second discriminating means for discriminating
If it is determined by the second determining means that the in-focus position is located within the overlapping range, the second relative position is set at a position where the imaging element and the zoom lens are separated by the second changing means. The imaging apparatus according to claim 1, wherein after the change, the focus position detection unit, the first determination unit, and the first focus control unit or the second focus control unit are caused to function. A detachable filter that transmits visible light without transmitting infrared light; and
Imaging means for outputting an image signal corresponding to a subject image formed on an image sensor via the filter and the imaging lens;
First relative position changing means for changing a first relative position of the imaging lens with respect to the imaging element;
A focus position detecting means for detecting the focus position by changing the first relative position within a first predetermined range;
A zoom lens that is disposed closer to the subject than the imaging lens and enlarges the subject image to form an image on the imaging device;
Second relative position changing means for changing a second relative position of the zoom lens with respect to the image sensor;
The in-focus position detected by the in-focus position detecting means with the filter removed after the second relative position is changed to a position where the imaging element and the variable magnification lens are separated from each other by the second changing means. Is a part of the first predetermined range, and a determination means for determining whether the second predetermined range is a scanning range for the visible light,
When the determining means determines that the in-focus position is within the second predetermined range, the in-focus operation is performed by changing the first relative position based on the tracking characteristic for the visible light. First focus control means;
If the determining means determines that the in-focus position is not within the second predetermined range, the in-focus operation is performed by changing the first relative position based on the tracking characteristics of the infrared light. An imaging apparatus comprising second focusing control means to be executed. A detachable filter that transmits visible light without transmitting infrared light; and
Imaging means for outputting an image signal corresponding to a subject image formed on an image sensor via the filter and the imaging lens;
Storage means for detecting a current first in-focus position in a state in which the filter is mounted, and storing the first in-focus position;
A relative position changing means for changing a relative position of the imaging lens with respect to the imaging element;
With the filter removed, an in-focus position detecting means for detecting the second in-focus position by changing the relative position within a predetermined range;
Difference detection means for detecting a difference between the first focus position and the second focus position;
When the difference detected by the difference detection unit is larger than a predetermined threshold value, a first focus control unit that executes a focusing operation by changing the relative position based on a tracking characteristic for the infrared light. When,
When the difference detected by the difference detection means is equal to or less than the predetermined threshold value, second focus control means for changing the relative position based on the tracking characteristic for the visible light and executing a focusing operation An imaging apparatus comprising:

Images