JP2011097264A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of imaging visible light and infrared light with accuracy, by using a single imaging optical system and a single image pickup device. <P>SOLUTION: The imaging apparatus is provided with the imaging optical system 3; the image pickup device 6, which has spectral sensitivity in a wavelength region which includes the wavelength extending from visible light to infrared light, and picks up an object image to be formed by transmitting the imaging optical system; an infrared cut filter 10 and a visible-light cut filter 11, one of which is selected and arranged so that it can be saved on the optical path of an object image from the imaging optical system 3; a first driving means 12 for arranging one selected cut filter on the optical path; a second driving means 13 for making the position of at least one of the imaging optical system 3 and the image pickup device 6 move to a position to be focused on the visible light or a position to be focused on the infrared light; and a control means 20 for controlling the first driving means 12 synchronized with the second driving means 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus capable of imaging visible light and infrared light with a single imaging optical system and imaging element.

  2. Description of the Related Art Conventionally, an imaging device that captures a subject image formed by an imaging optical system with an imaging device and outputs the subject image as an image is, for example, an in-vehicle camera, a digital still camera, a small camera for a portable terminal, an image inspection device, or the like It is widely used for various imaging devices. Since many image sensors used in such image pickup devices are generally sensitive not only to visible light but also to infrared light, the infrared component is removed by an infrared cut filter, and only visible light is imaged. A color image with good color reproducibility was obtained by being incident on the element.

  On the other hand, as described above, imaging devices using visible light mainly capture color images, but various imaging devices using infrared light have been proposed and put into practical use, which is often used for temperature measurement. It is used. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2009-150842), infrared light transmitted through an infrared lens is received by a far-infrared imaging device, and a temperature distribution of a subject image is detected based on a signal output from the far-infrared imaging device. An apparatus is disclosed.

  Furthermore, an imaging apparatus using both infrared light and visible light is disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2007-36831). This image pickup apparatus includes a visible light image sensor, an infrared light image sensor, and a reflection mirror that switches incident light to a visible light image sensor or an infrared light image sensor. For example, in an in-vehicle camera, a vivid image can be obtained even during night driving by combining a visible light image and an infrared light image captured by each image sensor.

  Patent Document 3 (Japanese Patent Laid-Open No. 2007-93652) discloses a first focusing position where a lens frame holding a lens is focused with respect to visible light and a first focus position where infrared light is focused. A lens driving device including a switching mechanism for switching between two in-focus positions is disclosed, and thereby, both visible light and infrared light having different focal lengths can be clearly imaged.

JP 2009-150842 A JP 2007-36831 A JP 2007-93652 A

However, as an imaging device using both infrared light and visible light, the imaging devices disclosed in Patent Literature 2 and Patent Literature 3 obtain a clear image of a subject image at daytime and nighttime in an in-vehicle camera, for example. It was not intended to measure the temperature of the subject.
Further, Patent Document 2 uses a reflection mirror for switching between infrared light and visible light, and requires two image pickup optical systems and two image pickup elements, which increases the product cost and increases the size of the apparatus. turn into.

Patent Document 3 is an invention of a lens drive device that switches between a focus position of visible light and a focus position of infrared light, and the image pickup apparatus is only equipped with this drive device to match the focus position of visible light. Infrared light enters the image sensor at the same time, and similarly, visible light also enters the image sensor aligned with the focus position of the infrared light. was there.
Therefore, an object of the present invention is to provide an imaging apparatus that can accurately capture visible light and infrared light with a single imaging optical system and imaging element.

  In order to solve the above problems, an imaging apparatus according to the present invention has an imaging optical system and spectral sensitivity in a wavelength region including wavelengths from visible light to infrared light, and forms an image through the imaging optical system. An image pickup device that picks up a subject image to be picked up, an infrared cut filter and a visible light cut filter that are selectively arranged to be retractable on the optical path of the subject image from the image pickup optical system, and the selected The first drive unit that arranges one cut filter on the optical path, and the position of at least one of the imaging optical system and the imaging element are set to a position that focuses on visible light or a position that focuses on infrared light. It is characterized by comprising second driving means for moving, and control means for controlling the first driving means and the second driving means in synchronization.

  According to the present invention, an imaging device having spectral sensitivity in a wavelength region including wavelengths from visible light to infrared light is used, switching of a cut filter arranged on the optical path, and a distance between the imaging optical system and the imaging device. Therefore, visible light and infrared light can be imaged with high accuracy by a single imaging optical system and imaging element. Therefore, the product cost can be reduced and the apparatus size does not increase.

In addition, when the infrared driving filter is arranged on the optical path by the first driving unit, the control unit sets the position of at least one of the imaging optical system and the imaging element by the second driving unit. It is preferable to move to a position that focuses on the visible light.
In this way, by arranging the infrared cut filter on the optical path, the infrared light is blocked, and the distance between the imaging optical system and the imaging element is set to a distance that focuses on the visible light, thereby taking the imaging optical. Visible light transmitted through the system can be accurately imaged on the image sensor.

Further, the control means sets the position of at least one of the imaging optical system and the imaging element by the second driving means when the visible light cut filter is arranged on the optical path by the first driving means. It is preferable to move to a position where the infrared light is focused.
As described above, the visible light is cut off by arranging the visible light cut filter on the optical path, and the distance between the imaging optical system and the imaging element is set to the distance that focuses on the infrared light, thereby taking the imaging optical. Infrared light that has passed through the system can be accurately imaged on the image sensor.

Further, it is preferable that the control device drives the first driving unit and the second driving unit in correspondence with a frame timing at which an image is picked up by the imaging element.
The image sensor is controlled so that an electrical signal photoelectrically converted is output at each frame timing. The first driving means and the second driving means are driven in correspondence with the frame timing, and visible light is transmitted. By alternately imaging infrared light, it is possible to perform imaging with the cut filter and the in-focus position appropriately set during imaging. Note that the first driving unit and the second driving unit may be controlled to be driven in synchronization every several frames.

Further, the output signal of the image sensor that has received visible light that has passed through the infrared cut filter is captured as image information, and the output signal of the image sensor that has received infrared light that has passed through the visible light cut filter is temperature information. It is preferable to further include a signal processing unit that captures and stores the image information and the temperature information in association with each other on the frame image.
In this way, by storing the image information obtained from visible light and the temperature information obtained from infrared light in association with each same position on the frame image, two types of information (image information and Temperature information) can be held, and this information is output appropriately, or is useful when signal processing is performed using either one or both of the information. The image information and the temperature information may be stored in separate tables and associated with each same position on the frame image. Alternatively, the temperature information at the same position may be embedded in the image information and stored in the same table. Also good.

Furthermore, the input means for designating a position on the frame image and the image information stored in the signal processing means are displayed, and the temperature information at the position designated by the input means is superimposed on the image information. It is preferable to further include display means for displaying the information.
In this way, by displaying the temperature information at the position on the frame image designated by the input means superimposed on the image information, only the temperature information necessary when the operator desires can be displayed on the image. It becomes possible.

Furthermore, display means for displaying the image information accumulated in the signal processing means and displaying the temperature information superimposed on the image information when the temperature information exceeds a preset threshold value. It is preferable to further provide.
As described above, the temperature information can be automatically displayed on the screen by superimposing the temperature information on the image information and displaying it only when a preset threshold value is exceeded.

  According to the present invention, an imaging device having spectral sensitivity in a wavelength region including wavelengths from visible light to infrared light is used, switching of a cut filter arranged on the optical path, and a distance between the imaging optical system and the imaging device. Therefore, visible light and infrared light can be imaged with high accuracy by a single imaging optical system and imaging element. Therefore, the product cost can be reduced and the apparatus size does not increase.

In addition, by placing an infrared cut filter on the optical path, the infrared light is cut off, and the distance between the imaging optical system and the imaging element is set to a distance that focuses on visible light, thereby reducing the imaging optical system. The transmitted visible light can be accurately imaged on the image sensor.
Furthermore, by arranging a visible light cut filter on the optical path, the visible light is blocked, and the distance between the imaging optical system and the imaging element is set to a distance that focuses on the infrared light, thereby reducing the imaging optical system. The transmitted infrared light can be accurately imaged on the image sensor.

1 is a side view illustrating a schematic configuration of an imaging apparatus according to an embodiment of the present invention. It is a side view which shows schematic structure of the imaging device which is a modification of FIG. It is a figure which shows a cut filter. It is a figure explaining operation | movement of a drive means, (A) A side view when imaging visible light, (B) is a side view when imaging infrared light. It is a whole block diagram of an imaging device containing the functional block diagram of a signal processing means. It is a figure which shows an example of (a) an example of a data structure in the case of displaying temperature information on image information, and (b) an example of a display screen. It is a figure which shows the specific example of a display screen. It is a figure which shows the other specific example of a display screen. It is a figure which shows an example of (a) data structure in the case of switching and displaying image information and temperature information, and (b) an example of a display screen. It is a figure which shows the timing chart which controls a drive means. It is a flowchart of signal processing.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the shape of the component described in this example is not intended to limit the scope of the present invention, but is merely an illustrative example.

1 is a side view showing a schematic configuration of an imaging apparatus according to an embodiment of the present invention, FIG. 2 is a side view showing a schematic configuration of an imaging apparatus which is a modification of FIG. 1, and FIG. 3 is a diagram showing a cut filter. FIG. 4 is a diagram for explaining the operation of the driving means.
An imaging apparatus 1 according to an embodiment of the present invention mainly includes an imaging optical system 3, an imaging element 6, an infrared cut filter 10, a visible light cut filter 11, an infrared cut filter 10, and a visible light cut filter. 11, a first driving unit 12 that arranges one of them on the optical path, a second driving unit 13 that displaces the distance between the imaging optical system 3 and the imaging element 6, a first driving unit 12, and a first driving unit 12. Control means 20 for controlling the two drive means 13 in synchronization.

The imaging optical system 3 includes one or a plurality of lenses, is arranged on the optical axis, and is held by the lens holder 2.
One of the infrared cut filter 10 and the visible light cut filter 11 is selectively arranged on the optical path of the subject image from the imaging optical system 3 so as to be retractable.
The first driving unit 12 arranges one of the infrared cut filter 10 and the visible light cut filter 11 on the optical path of the subject image from the imaging optical system 3. For example, as shown in FIGS. 1 and 2, the specific configuration of the first driving unit 12 connects the infrared cut filter 10 and the visible light cut filter 11 so that the same plane is formed. The cut filters 10 and 11 are rotated by the first driving means 12 so that one of the cut filters is arranged on the optical path. As another configuration example, the infrared cut filter 10 and the visible light cut filter 11 connected as shown in FIG. 3 are slid on the straight line in the direction of the arrow in the figure by the first driving means 12. Also good. Note that the configurations of the cut filters 10 and 11 and the first driving unit 12 are not limited to the above-described example.

  The image sensor 6 is disposed on the substrate 5 and has spectral sensitivity in a wavelength region including wavelengths from visible light to infrared light. That is, the image sensor 6 can detect light in the wavelength region. Note that the spectral sensitivity of the image sensor 6 does not need to include all of the wavelength region of infrared light, and may include a wavelength region corresponding to a temperature range required for temperature measurement. Preferably, the image sensor 6 has spectral sensitivity in a wavelength region including a visible region of 400 to 700 nm and an infrared region of about 0.5 to 2.0 μm. For example, a photodiode of a quantum detection element using InGaAs is known as the imaging element 6 having spectral sensitivity in a wavelength region including the visible region and the infrared region, and among these, a high value of 0.5 to 1.7 μm is known. A short-wavelength high-sensitivity type InGaAs photodiode having spectral sensitivity is preferably used. With this photodiode, an image can be taken using visible light, and the temperature can be measured up to about 200 ° C. using infrared light. The type of the image sensor 6 is not particularly limited, but for example, a CCD and a CMOS are used.

  The second driving unit 13 moves at least one position of the imaging optical system 3 and the imaging element 6 to a position that focuses on visible light or a position that focuses on infrared light. FIG. 1 shows a case where the imaging element 6 side is moved, and FIG. 2 shows a case where the imaging optical system 3 side is moved. As the first driving means 12 or the second driving means 13, for example, an actuator such as a piezoelectric element or a motor is used. Although not shown, both the imaging optical system 3 and the imaging element 6 are arranged such that the second driving means 13 is disposed between the imaging optical system 3 and the imaging element 6 so that a desired focal length is obtained. May be moved.

The control unit 20 generates a control signal for controlling the first driving unit 12 and the second driving unit 13 in synchronization with each other, and transmits the control signal to the first driving unit 12 and the second driving unit 13. . With reference to FIG. 4, the operation of the driving means controlled by the control means 20 will be described. Here, as an example, the case where the second driving means 13 is provided on the image sensor 6 side is shown.
FIG. 4A is a side view when imaging visible light. When imaging visible light, the first drive unit 12 arranges the infrared cut filter 10 on the optical path, and the second drive unit 13 moves the imaging device 6 to a position where the visible light is focused.

On the other hand, FIG. 4B is a side view when imaging infrared light. When imaging infrared light, the visible light cut filter 11 is arranged on the optical path by the first driving unit 12, and the imaging element 6 is moved to a position where the imaging element 6 is focused on the infrared light by the second driving unit 13. .
Since the focus position of the visible light is shorter than the focus position of the infrared light, the distance f ₁ between the imaging optical system 3 and the imaging element 6 when imaging the visible light in FIG. B) is shorter than the distance f ₂ between the imaging optical system 3 and the imaging element 6 when imaging infrared light.

  As described above, the imaging apparatus 1 according to the present embodiment uses the imaging element 6 having spectral sensitivity in a wavelength region including wavelengths from visible light to infrared light, and switches the cut filters 10 and 11 disposed on the optical path. Since the switching of the distance between the imaging optical system 3 and the imaging element 6 is controlled in synchronization, the single imaging optical system 3 and the imaging element 6 capture visible light and infrared light with high accuracy. It becomes possible. Therefore, the product cost can be reduced and the apparatus size does not increase.

Further, by arranging the infrared cut filter 10 on the optical path, the infrared light is blocked, and the distance between the imaging optical system 3 and the imaging element 6 is set to a distance that focuses on the visible light, thereby capturing an image. Visible light transmitted through the optical system 3 can be imaged on the image sensor 6 with high accuracy.
Further, by arranging the visible light cut filter 11 on the optical path, the visible light is blocked, and the distance between the imaging optical system 3 and the imaging element 6 is set to a distance that focuses on the infrared light, thereby capturing an image. Infrared light that has passed through the optical system 3 can be accurately imaged on the image sensor 6.

FIG. 5 is an overall block diagram of the imaging apparatus 1 including a functional block diagram of the signal processing means 21.
As shown in FIG. 5, the imaging apparatus 1 further includes a signal processing unit 21 that processes an output signal from the imaging device 6, and a storage unit 28 and a display unit 30 connected to the signal processing unit 21. preferable.
The signal processing means 21 includes a visible / infrared determination unit 22, an image information generation unit 23, a temperature information generation unit 24, an image / temperature superimposition unit 25, and a timing generation unit 26. The signal processing means 21 is composed of, for example, an MPU (microprocessor). The MPU may include the control means 20 and control the first drive means 12 and the second drive means 13.

The visible / infrared determination unit 22 determines whether the electrical signal output from the imaging device 6 is a signal output by receiving visible light or a signal output by receiving infrared light. To do.
The image information generation unit 23 generates image information based on an electrical signal (hereinafter referred to as a visible light signal) output by receiving visible light. Specifically, processing selected from image processing such as AWB (auto white balance) processing, AE (exposure control) processing, color correction processing, interpolation processing, and edge enhancement processing is performed on the RGB values of the visible light signal. Go to generate image information. However, there may be a case where control is performed by returning the AE and AWB information to the image sensor 6.
The temperature information generation unit 24 generates temperature information based on an electrical signal (hereinafter referred to as an infrared light signal) output by receiving infrared light. Specifically, the luminance value (output level) or the light amount of each pixel is obtained from the infrared light signal, and the subject temperature is calculated based on this to generate temperature information.

  The storage means 28 stores the image information generated by the image information generation unit 23 and the temperature information generated by the temperature information generation unit 24 in association with each other at the same position on the frame image. Note that the image information and the temperature information may be stored in separate tables and associated with each other at the same position on the frame image, or the same table may be embedded in the image information with the temperature information at the same position on the frame image. May be stored.

  The image / temperature superimposing unit 25 superimposes the temperature information selected from the temperature information generated by the temperature information generating unit 24 on the image information generated by the image information generating unit 23. The temperature information to be superimposed on the image information may be temperature information at a position on the frame image designated by the input means 31, so that only temperature information necessary when the operator desires can be displayed on the screen. It becomes possible. Further, a temperature threshold value may be set in advance, and temperature information exceeding this threshold value may be superimposed on the image information, whereby the temperature information can be automatically displayed on the screen.

The display means 30 mainly displays the image information and displays the temperature information superimposed on the image information as necessary, or displays only the temperature information by switching from the image information to the temperature information.
FIG. 6 is a diagram showing an example of (a) a data structure and (b) an example of a display screen when temperature information is displayed superimposed on image information. As shown in FIG. 6A, the data structure of one pixel is composed of, for example, 8-bit image information 41 and 8-bit temperature information 42, and as shown in FIG. Information 42 is embedded and displayed. Examples of the screen of the display means 30 at this time are shown in FIGS. FIG. 7 shows an example in which the temperature information 47 is numerically displayed on the image information 46. FIG. 8 shows an example in which the temperature information 48 is displayed on the image information 46 in color. For example, the color corresponding to the temperature is set in advance, such as red for the high temperature portion and blue for the low temperature portion, and the temperature information to be displayed is converted into a color and superimposed on the image information 46.

  FIG. 9 is a diagram showing an example of (a) a data structure and (b) an example of a display screen when switching between image information and temperature information for display. As shown in FIG. 6A, the data structure of one pixel is composed of, for example, 8-bit image information 41 and 8-bit temperature information 42. Among these, the image information 41 is used to display the image 43 on the display means 30. If necessary, the display screen is switched to display the temperature 44.

The timing generation unit 26 generates a timing signal (clock pulse) for detecting an electrical signal photoelectrically converted by the image sensor 6. Frame timing is determined by this timing signal. The image sensor 6 is controlled so that, for example, photoelectric conversion is performed at each frame timing and an electric signal is output. Preferably, it is preferable to output at a frame rate of 30 sheets per second in the visible region and at a frame rate of 30 sheets per second in the infrared region. This is because the image looks smooth to the human eye when it is 30 frames / second or more.
In the present embodiment, as shown in FIG. 10, the drive signal that the control unit 20 controls the first drive unit 12 and the second drive unit 13 in correspondence with the timing signal generated by the timing generation unit 26. Is preferably output. Thereby, at the time of imaging, imaging can be performed in a state where the cut filters 10 and 11 and the in-focus position are appropriately set. Note that the control unit 20 may perform control so that the first driving unit 10 and the second driving unit 11 are driven in synchronization every several frames.

Next, the flow of the signal processing means 21 will be described with reference to FIG.
The output signal from the image sensor 6 is input to the signal processing means 21 (S1), and after the correlated double sampling, A / D conversion, etc. are performed, the visible / infrared determination unit 22 inputs the input electrical signal. It is determined whether the signal is a visible light signal or an infrared light signal (S2). When the visible / infrared determination unit 22 determines that the signal is a visible light signal, the image information generation unit 23 performs visible light signal processing such as AWB processing and AE processing on the RGB value of the visible light signal. (S3) Image information is generated (S4). If it is determined that the signal is an infrared light signal, the temperature information generation unit 24 performs infrared light signal processing for calculating the subject temperature based on the luminance value or light amount of the infrared light signal (S5), and the temperature Information is generated (S6).

The image information generated by the image information generation unit 23 and the temperature information generated by the temperature information generation unit 24 are associated with each other at the same position on the frame image and accumulated in the storage unit 28.
Image information or temperature information stored in the storage means 28 is taken out as necessary and displayed on the display means 30. For example, if a threshold value is set in advance in the signal processing means 21 and the temperature information is larger than the threshold value (S7), the image / temperature superimposing unit 25 superimposes the image information and the temperature information (S8). ) And screen display on the display means 30 (S9).
According to the present embodiment, a temperature image obtained by imaging with infrared light is superimposed and displayed on an image captured with visible light, thereby displaying a color image equivalent to that actually seen by a human being. The temperature information of the subject can be recognized at the same time. This imaging device 1 is used for an in-vehicle camera, a monitoring camera, and the like, and is also preferably used for recognizing a living thing such as a person or an animal in an image, for example.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Lens holder 3 Imaging optical system 5 Board | substrate 6 Imaging element 10 Infrared cut filter 11 Visible light cut filter 12 1st drive means 13 2nd drive means 20 Control means 21 Signal processing means 22 Visible / infrared determination Unit 23 image information generating unit 24 temperature information generating unit 25 image / temperature superimposing unit 26 timing generating unit 28 storage unit 30 display unit 31 input unit

Claims (7)

An imaging optical system;
An image sensor that has a spectral sensitivity in a wavelength region including wavelengths from visible light to infrared light, and that images a subject image that is transmitted through the imaging optical system; and
On the optical path of the subject image from the imaging optical system, one of the infrared cut filter and the visible light cut filter that is selectively disposed so as to be retractable;
First driving means for arranging the selected one cut filter on the optical path;
Second driving means for moving at least one of the imaging optical system and the imaging device to a position for focusing on visible light or a position for focusing on infrared light;
An imaging apparatus comprising: control means for controlling the first driving means and the second driving means in synchronization.   When the infrared driving filter is disposed on the optical path by the first driving unit, the control unit determines the position of at least one of the imaging optical system and the imaging element by the second driving unit. The imaging apparatus according to claim 1, wherein the imaging apparatus is moved to a position where the light is focused.   When the visible light cut filter is arranged on the optical path by the first driving means, the control means sets the position of at least one of the imaging optical system and the imaging element to the red color by the second driving means. The imaging apparatus according to claim 1, wherein the imaging apparatus is moved to a position where it is focused on outside light.   4. The control device according to claim 1, wherein the control device drives the first driving unit and the second driving unit in correspondence with a frame timing at which an image is picked up by the imaging element. 5. The imaging device according to item.   The output signal of the image sensor that has received visible light that has passed through the infrared cut filter is captured as image information, and the output signal of the image sensor that has received infrared light that has passed through the visible light cut filter is captured as temperature information. 5. The imaging apparatus according to claim 1, further comprising: a signal processing unit that associates and stores the image information and the temperature information for each same position on the frame image. Input means for designating a position on the frame image;
The image processing apparatus further comprises display means for displaying the image information stored in the signal processing means and displaying the temperature information at a position specified by the input means superimposed on the image information. Item 6. The imaging device according to Item 5.   The image processing apparatus further includes display means for displaying the image information accumulated in the signal processing means and displaying the temperature information superimposed on the image information when the temperature information exceeds a preset threshold value. The imaging apparatus according to claim 5.

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