JP2014157202A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a deviation of a focus position generated due to insertion/retraction of an infrared cut filter or use of a different light source without cumbersome settings.SOLUTION: An imaging device includes: determination means that determines a focus position from position information on a focus lens 103 of an imaging optical system 101 and a captured image acquired from an imaging sensor; filter movement means that performs insertion/retraction of an infrared cut filter 122 on an optical path of the imaging optical system; estimation luminance calculation means that calculates luminance to be estimated from the captured image; first infrared cut filter movement means that automatically inserts/retracts the infrared cut filter on the basis of the estimated luminance calculated by the estimation luminance calculation means; and second infrared cut filter movement means that manually inserts/retracts the infrared cut filter. When the filter movement is performed by using the first infrared cut filter movement means, an amount of a correction of a focus position acquired under a fluorescent lamp is used, and when the filter movement is performed by using the second infrared cut filter movement means, an amount of a correction of a focus lens position under an infrared illumination light is used.

Description

  The present invention relates to an imaging apparatus that changes a correction amount of a focus lens position for each photographing mode corresponding to insertion / extraction of an infrared cut filter.

  An imaging device is known as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor that performs photoelectric conversion to form an image of light, receive a subject image, and convert the collected light into an electrical signal. The element is mounted. In this imaging device, a color filter is arranged for each pixel on the imaging surface to generate a color image. However, in addition to visible light that can be seen by the human eye, the color filter also transmits infrared light that cannot be seen by the human eye. In general, the imaging element has sensitivity beyond the visible light (red component: 750 nm) to the infrared region. In view of this, an imaging apparatus usually uses an infrared cut filter between the condenser lens and the imaging element to remove the infrared component and express the color. If unnecessary infrared components are not removed without using this infrared cut filter, the entire photographed image becomes a reddish image.

  On the other hand, an imaging apparatus used for monitoring purposes or the like may be used in a low illuminance state where there is little light quantity or no light such as at night. In this case, the infrared cut filter is removed from the optical path between the lens and the image pickup device to improve the sensitivity of the image pickup device and use the image to the infrared region. Furthermore, the subject can be recognized even in a dark environment by photographing the subject by irradiating the subject with infrared light using an infrared projector. In the case of this night photographing, the photographed image is often photographed as a black and white image.

  Regarding the insertion / extraction of these infrared cut filters, an infrared cut filter insertion / extraction mechanism is mounted on the imaging device, and switching between insertion and extraction is performed in accordance with the amount of light input to the lens. If the amount of light is above a certain threshold, an infrared cut filter is inserted, and if it is below the threshold, the infrared cut filter is automatically removed. In addition, there is a user who arbitrarily switches between insertion and removal.

  However, when the determination of the insertion / extraction of the infrared cut filter is automatically performed, it is difficult to use it under infrared illumination. This is because the ratio of the amount of infrared light and the amount of visible light included in the light incident from the subject is not constant, and the threshold is determined based on the amount of light with the infrared cut filter inserted, and the removal is determined. When the outer cut filter is removed, the amount of light increases due to the infrared light of the infrared illumination, and the insertion is determined again. Since a hunting phenomenon that repeats this insertion / extraction determination occurs, automatic determination of insertion / extraction becomes difficult with infrared illumination.

  In addition, when the infrared cut filter is inserted or removed, the focal position of the lens may be shifted. This is due to the difference in the refractive index of light by the lens, and the wavelength component included in the illumination changes due to the insertion / extraction of the infrared cut filter. In order to compensate for this change, it is necessary to correct the focus position.

  In Patent Document 1, switching control of the infrared cut filter is performed in response to a change in the amount of infrared light in the shooting environment. This is controlled by calculating the difference in gain amount of the automatic gain control AGC generated by the insertion / extraction of the infrared cut filter.

  In Patent Document 2, the setting process is performed by changing the driving range of the imaging lens when the infrared cut filter is inserted and removed. This corresponds to the problem that the in-focus position differs depending on the insertion / extraction of the infrared cut filter, and the problem that the optimum lens driving range is different even when using the contrast-type automatic focusing function.

JP 2010-93525 A JP 2002-221656 JP

  However, in the conventional technique disclosed in Patent Document 1 above, the infrared cut filter insertion / extraction control is not divided into the automatic mode and the manual mode, and the difference between the use environment in the automatic mode and the use environment in the manual mode. There is a problem that cannot be handled.

  Also in the prior art disclosed in Patent Document 2, the infrared cut filter insertion / extraction control is not divided into the automatic mode and the manual mode, and is more optimal when performing control incorporating changes in the environment. Can be considered.

  In view of this, an object of the present invention is to appropriately prevent a focus correction position shift due to infrared cut filter insertion / extraction taking into account the actual use environment in the mode in which the infrared cut filter is automatically inserted / removed and the mode in which the infrared cut filter is manually performed. .

In order to achieve the above object, an imaging apparatus according to the present invention includes an imaging optical system including a focus lens, an imaging sensor that receives and photoelectrically converts a subject image formed by the imaging optical system, and the imaging optical system. Determination means for determining the in-focus position from the position information of the focus lens and the captured image obtained from the imaging sensor, filter moving means for inserting / removing an infrared cut filter in the optical path of the imaging optical system, and the captured image An estimated luminance calculating means for calculating an estimated luminance, a first infrared cut filter moving means for automatically inserting / removing an infrared cut filter from the estimated luminance calculated by the estimated luminance calculating means, and an infrared cut manually An imaging apparatus having a second infrared cut filter moving means for inserting and removing a filter,
When performing the filter movement using the first infrared cut filter moving means, use the in-focus position correction amount acquired under the fluorescent lamp,
When the filter is moved using the second infrared cut filter moving means, a focus lens position correction amount under infrared illumination is used.

  According to the present invention, since the light source is changed according to the mode for controlling the insertion / extraction of the infrared cut filter, the focus position deviation can be suppressed without complicated setting by changing the focus position correction amount to match the light source. .

It is a block diagram showing an example of an imaging device in a 1st embodiment of the present invention. It is the follow chart figure which showed the process of the imaging device in the 1st Embodiment of this invention. It is the figure which showed the shift | offset | difference of the focus position at the time of the infrared cut filter insertion under normal light source, and extraction. It is a flowchart figure explaining the means which a user selects and correct | amends each light source of the imaging device in the 2nd Embodiment of this invention. It is the figure which showed the shift | offset | difference of the focus position by the illumination used at the time of infrared cut filter removal. It is the figure which showed the means to set the focus correction value in the 3rd Embodiment of this invention by GUI.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

<First Embodiment>
First, a first embodiment of the present invention will be described.

  FIG. 1 is a block diagram illustrating an example of an imaging apparatus according to the first embodiment of the present invention.

  The imaging device 120 includes an imaging optical system 101, a zoom lens 102, a focus lens 103, an infrared illumination 123, a filter drive mechanism 104 including an optical path length correction filter 121 and an infrared cut filter 122, and an imaging element that converts incident light into electric charges. 105, A / D conversion unit 106, video signal processing unit 107, encoder unit 108, network processing unit 109, estimated luminance calculation unit 110, storage unit 111, CPU 112, focus lens driving unit 113, zoom lens driving unit 114, stepping motor 115, 116, 117. A network unit 118 and an external input / output unit 119 are provided outside.

  In the imaging optical system 101, light is collected through the zoom lens 102 and the focus lens 103. The collected light passes through a filter driving mechanism 104 including an optical path length correction filter 121 and an infrared cut filter 122. Here, the infrared cut filter 122 has a role of removing unnecessary infrared components in the optical image obtained by the optical system. On the other hand, the optical path length correction filter 121 undergoes a change that the optical path length increases when the infrared cut filter is inserted. This causes a difference in focus position. Therefore, a dummy filter is inserted so as to obtain the optical path length when the infrared cut filter is inserted.

  In addition, infrared light can be lowered onto the subject using the infrared illumination 123 according to the insertion / extraction of the infrared cut filter. By dropping the infrared illumination when the infrared cut filter is removed, it is possible to recognize the subject even in an environment having a lower illuminance image or no illuminance by using the sensitivity of the image sensor 105. The infrared illumination 123 is built in the imaging device 120. However, the infrared illumination 123 is a device that can be used from the outside and the type of illumination can be changed.

  The light that has passed through the filter drive mechanism 104. Light is received by the image sensor 105 that accumulates charges and performs photoelectric conversion according to the amount of light received, such as a CCD or CMOS sensor.

  The A / D converter 106 digitally converts an analog signal from the image sensor 105.

  The video signal digitized by the A / D converter 106 is transmitted to the video signal processing unit 107. The video signal processing unit 107 performs processing such as improving the image quality of the input video signal or outputting a reset signal for clearing the accumulated charge to the image sensor 105.

  The encoder unit 108 performs encoding such as creation and compression processing of a video signal having a size necessary for displaying video with an input / output device 119 described later. The compressed video signal is sent to the network processing unit 109.

  The network processing unit 109 distributes the video signal output from the imaging device 120 to the network 118. The video signal sent to the network is received by the input / output device 119. The input / output device 119 has a display device, and a user can view images as a viewer.

  A signal generated when the user operates the operation screen on the input / output device 119 is transmitted to the network processing unit 109 of the imaging apparatus 120 via the network unit 118 and transmitted to the CPU 112 via the encoder unit 108. . The CPU 112 controls the image sensor 105 and each motor according to the received command.

  Based on the image data acquired from the video signal processing unit 107, the AF processing unit 123 calculates the contrast. The high-frequency component is extracted from the video signal from the video signal processing unit through a high-pass filter and acquired as a contrast value. The calculation is performed while the focus lens 103 is moved minutely, and when the contrast value increases, the calculation proceeds in the same direction. When the contrast value decreases, the calculation is performed in the opposite direction. If the contrast value decreases in either direction, it is determined as the position with the highest contrast value and is set as the in-focus position. The result of this determination is sent to the CPU 112 described later.

  Here, the shift of the in-focus position when the infrared cut filter is inserted and removed under a normal light source will be described with reference to FIG.

  It shows the output of the contrast (focus evaluation value) when the same subject is photographed at infinity under a normal light source. The horizontal axis is the drive pulse position of the focus lens, the right is closest and the left is infinity, and the vertical axis indicates contrast (focus evaluation value). For example, the waveform 301 indicates the focus position when the infrared cut filter is inserted. By the focusing means described above, the focusing position A is a position where the infrared cut filter is focused when inserted. On the other hand, the waveform 302 is a waveform when the infrared cut filter is removed. The focus position B is a position where the infrared cut filter is focused when removed. Even when the same light source is used, the focus position at the time of inserting and removing the infrared cut filter is different.

  On the other hand, the estimated luminance calculation unit 110 calculates for use as a value for controlling the drive of the filter drive mechanism 104 including the optical path length correction filter 121 and the infrared cut filter 122.

  Here, the estimated luminance value in the screen is calculated based on the image data acquired from the video signal processing unit 107.

  The storage unit 111 can write to a specified address, and also has a function of reading data at a specified address from a storage device (such as SDRAM) that can read from the specified address or nonvolatile data. It is configured by a storage device (FlashROM or the like).

  In the present embodiment, since SDRAM can perform high-speed writing and reading, it stores programs and data applied to each control unit and is also used as a work area for executing various programs. In addition, a nonvolatile storage element such as FlashROM is used as a permanent storage area for various programs and data.

  The CPU 112 transmits a lens driving amount and a filter insertion / extraction instruction to each motor driver based on the video signal in the video signal processing unit 107, the contrast value in the AF processing unit, and the estimated luminance value calculated in the estimated luminance calculating unit 110. To do. In addition, it is possible to instruct the dropping of the infrared illumination 123.

  When the threshold value of the estimated luminance value stored in the storage unit 111 is acquired and it is determined that the estimated luminance value is brighter than the brightness of the threshold value, an infrared cut filter 122 is inserted. An instruction is given to remove the cut filter 122 and insert the optical path length correction filter 121.

  Next, this embodiment will be described in detail with reference to the flowchart of FIG.

  Conventionally, when using the first infrared cut filter moving means that automatically inserts and removes the infrared cut filter from the estimated brightness calculated by the estimated brightness calculating means, it cannot be used under infrared illumination (hunting Due to the influence). Further, it has been empirically found that when the second infrared cut filter moving means for manually inserting and removing the infrared cut filter is used, infrared illumination is turned on and used.

  That is, in many cases, light sources having different wavelength components are used in the mode in which the infrared cut filter is automatically inserted and removed and in the case where it is manually performed. However, since the correction is actually performed with the same focus lens correction amount, there is a problem that the focus position is shifted due to the change in the environment. In order to solve this problem, means for changing the focus correction amount when the infrared cut filter is inserted will be described with reference to FIG.

  First, 201 is selected whether the means for inserting and removing the infrared cut filter is the automatic mode or the manual mode. If the infrared cut filter insertion / extraction is in the automatic mode, the CPU is notified 202 that the infrared cut filter movement is automatic 202. The notified CPU operates in a mode in which the insertion / extraction determination is performed from the estimated luminance. When this infrared cut filter is in the automatic insertion / removal mode, the surrounding environment is used under fluorescent lighting (it is known that infrared light is not turned on), so the focus lens The correction amount is fixed to the correction amount under the fluorescent lamp 203. The position of the focus lens is corrected 204 with the fluorescent lamp correction amount. The correction amount used in 203 and 204 is a value obtained by measuring the deviation caused by the difference in refractive index due to the removal of the infrared cut filter under the fluorescent lamp in the storage unit 111 and inserting / removing the infrared cut filter. Change according to the mode.

  When the correction is completed, this value is continued to be used until the estimated luminance value becomes equal to or less than the threshold value 205. If the estimated luminance value exceeds the threshold value, an infrared cut filter is inserted, and the operation at the time of removing the infrared cut filter is terminated.

  On the other hand, if the manual mode is selected in 201 for selecting whether the means for inserting / removing the infrared cut filter is the automatic mode or the manual mode, the CPU notifies the CPU that the infrared cut filter movement is automatic 207. The notified CPU performs the insertion / extraction determination as instructed by the external input / output unit. At this time, when an instruction to remove the infrared cut filter is given from the outside, the luminance around the subject is usually at low illuminance, and the user has empirically found that the infrared illumination is turned on. Therefore, the focus correction amount is fixed 208 to the correction amount under the infrared light lamp. The position of the focus lens is corrected 209 with the correction amount under the infrared lamp. The correction amount used in 208 and 209 is a value obtained by measuring the deviation caused by the difference in refractive index due to the removal of the infrared cut filter under the fluorescent lamp in the storage unit 111, and inserting and removing the infrared cut filter. Change according to the mode.

  When the user selects insertion of the infrared cut filter through the external device 210, the infrared cut filter is inserted, and the operation at the time of removing the infrared cut filter is terminated.

  The above is the description of the operation in the automatic mode or the manual mode as the means for inserting / removing the infrared cut filter when the infrared cut filter is removed. By performing these processes, in the present embodiment, it is possible to perform an appropriate focus position correction considering that the environment changes depending on the difference between the automatic mode and the manual mode of the infrared cut filter used.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.

  The configuration of the image pickup apparatus in the second embodiment is the same as that shown in FIG. 1 in the first embodiment, and a description thereof will be omitted. In the first embodiment described above, the means for inserting and removing the infrared cut filter uses different correction amounts in the automatic mode and the manual mode. On the other hand, in the second embodiment, when the means for inserting / removing the infrared cut filter is in the manual mode, it is possible to select a light source to be used simultaneously.

This causes a problem that, when the infrared cut filter is manually removed, if the actual illumination is under a fluorescent lamp, the focus position is shifted if correction is performed with the correction amount under the infrared lamp.
In order to solve this problem, a means for correcting the light source by the user selecting each light source will be described with reference to the flowchart of FIG.

  First, the means for inserting / removing the infrared cut filter is selected 401 to select the automatic mode or the manual mode. When the infrared cut filter insertion / extraction is in the manual mode, the user selects 402 whether to remove the infrared cut filter. When not, the user selects whether the infrared cut filter insertion / extraction is set to the automatic mode or the manual mode.

  When removing the infrared cut filter, the illumination to be used is selected. Here, the focus position shifts as shown in FIG. 5 depending on the illumination used.

  501, 502, 503, and 504 in FIG. 5 indicate in-focus positions under a fluorescent lamp, an incandescent lamp, an infrared illumination (860 nm), and an infrared illumination (940 nm) when the infrared cut filter is removed. , B, C, C. Here, the horizontal axis is the drive pulse position of the focus lens, the right is closest, the left is infinity, and the vertical axis indicates contrast (focus evaluation value). It shows the output of the contrast (focus evaluation value) when the same subject is photographed at infinity. Specifically, when the in-focus position A under the fluorescent lamp is used as a reference, the value described below is obtained by calculating with the driving pulse of the motor driving the focus lens. The focusing position B under the incandescent lamp is A + 7, the focusing position C under the infrared lamp (860 nm) is A + 24, and the focusing position D under the infrared lamp (860 nm) is A + 32.

  In order to correct this deviation, a focus correction position is selected 404 by the selected illumination. The focus position is corrected 405 to the selected correction position. The focus position is corrected 406 with the correction amount described above until the user selects the insertion of the infrared cut filter. The above explains the operation in the manual mode of the means for inserting and removing the infrared cut filter when the infrared cut filter is removed. By performing these processes, in the present embodiment, it is possible to perform more accurate focus position correction by selecting what kind of light source is the current photographing light source in the automatic mode of insertion / extraction of the used infrared cut filter. Can do.

<Third Embodiment>
Next, a third embodiment of the present invention will be described.

  The configuration of the imaging apparatus according to the third embodiment is the same as that illustrated in FIG. 1 according to the first embodiment, and thus the description thereof is omitted.

  The illumination which can be selected by the first infrared cut filter moving means for automatically inserting / removing the infrared cut filter and the second infrared cut filter moving means for manually inserting / removing the infrared cut filter is changed. It is said.

  Means for specifically realizing the first embodiment and the second embodiment described above by GUI (Graphical User Interface) will be described.

  FIG. 6 shows a viewer display screen when an image captured by the imaging device is viewed using the external device 119. Reference numeral 601 denotes the entire viewer, reference numeral 602 denotes a captured image (photographed subject), reference numeral 603 denotes an operation unit that can select the setting of the imaging apparatus, and reference numeral 604 denotes detailed settings for the imaging apparatus setting item selected in 603. This is a screen that can be used. This time, various settings by inserting and removing the infrared cut filter will be described. Further, the case where the infrared cut filter insertion / extraction determination is divided into the automatic mode and the manual mode using 604A and 604B will be described.

  In 604A, the infrared cut filter insertion / removal mode is the automatic mode, and in 605, the current insertion / removal mode is displayed. Reference numeral 606 indicates whether the infrared cut filter is currently ON: inserted or OFF: not inserted. A light source that can be used at present is displayed at 607. This is because, when the infrared cut filter insertion / extraction mode is the automatic mode, the use of infrared light or the like is generally not used due to the influence of hunting or the like. Fluorescent lamp Two incandescent lamps are displayed.

  Reference numeral 608 indicates which light source is used as the current focus position correction value.

  On the other hand, in 604B, the infrared cut filter insertion / removal mode is the manual mode, and in 609, the current insertion / removal mode is displayed. In the case of the manual mode, settings 610 to 612 described below can be changed manually. Reference numeral 610 indicates whether the infrared cut filter is currently ON: inserted or OFF: not inserted. In 611, the type of the light source currently used can be selected. This may be the light source used in the infrared light 122 of FIG. 1, or the light source that is projecting from the outside may be selected. Further, in manual mode: Fluorescent lamp Incandescent light Infrared light 1 (860 nm) 4. Different values can be set for the infrared light 2 (940 nm) and the automatic mode.

  As described above, the correction amount that can be set when the infrared cut filter is inserted / removed in the automatic mode or the manual mode is corrected according to the light source, so that it can be corrected to an appropriate value without complicated settings. .

<Other embodiments>
As mentioned above, although embodiment of this invention has been explained in full detail based on drawing, this invention is not limited to these specific embodiment, Various forms of the range which does not deviate from the summary of this invention are also included in this invention. included. A part of the above-described embodiments may be appropriately combined.

  Also, the light source used is not limited to the fluorescent lamp, incandescent lamp, infrared light (860 nm), and infrared light (940 nm) shown in FIG. 5, and the correction amount should be set according to the light source used. Is also considered enough.

101: Imaging optical system
102 ... Zoom lens
103 ... Focus lens
104 ... Filter drive mechanism
105 ... Image sensor
106 ・ ・ ・ A / D converter
107 ... Video signal processing
108 ・ ・ ・ Encoder
109 ・ ・ ・ Network processing unit
110 ... Estimated brightness calculator
111 ・ ・ ・ Storage unit
112 ... CPU
113 ・ ・ ・ Focus lens drive unit
114 ... Zoom lens drive
115 ... Stepping motor
116 ... Stepping motor
117 ... Stepping motor
118 ・ ・ ・ Network part
119 ・ ・ ・ External input / output section
120 ... Imaging device
121 ... Optical path length correction filter
122 ・ ・ ・ Infrared cut filter
123 ・ ・ ・ Infrared illumination

Claims (3)

An imaging optical system including a focus lens, an imaging sensor that receives and photoelectrically converts a subject image formed by the imaging optical system, position information of the focus lens of the imaging optical system, and imaging obtained from the imaging sensor Determining means for determining a focus position from an image; filter moving means for inserting / removing an infrared cut filter in an optical path of the imaging optical system; estimated brightness calculating means for calculating estimated brightness from a captured image; First infrared cut filter moving means for automatically inserting / removing the infrared cut filter from the estimated luminance calculated by the luminance calculating means, and second infrared cut filter moving means for manually inserting / removing the infrared cut filter An imaging device having
When performing the filter movement using the first infrared cut filter moving means, use the in-focus position correction amount acquired under the fluorescent lamp,
An image pickup apparatus using a focus lens position correction amount under infrared illumination when a filter is moved using the second infrared cut filter moving means. An imaging optical system including a focus lens, an imaging sensor that receives and photoelectrically converts a subject image formed by the imaging optical system, position information of the focus lens of the imaging optical system, and imaging obtained from the imaging sensor Determining means for determining a focus position from an image; filter moving means for inserting / removing an infrared cut filter in an optical path of the imaging optical system; estimated brightness calculating means for calculating estimated brightness from a captured image; First infrared cut filter moving means for automatically inserting / removing the infrared cut filter from the estimated luminance calculated by the luminance calculating means, and second infrared cut filter moving means for manually inserting / removing the infrared cut filter An imaging device having
When the filter movement is performed using the second infrared cut filter moving means, when selecting the insertion / extraction of the infrared cut filter, the illumination information is also selected, and each illumination is selected according to the selected illumination. The imaging apparatus according to claim 1, wherein a lower focus lens position correction amount is used. The illumination information includes illumination that can be selected by a first infrared cut filter moving unit that automatically inserts and removes the infrared cut filter and a second infrared cut filter move unit that manually inserts and removes the infrared cut filter. The imaging apparatus according to claim 1, wherein the imaging apparatus is changed.